担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for Cancer Research (AACR)  

Abstract

SLFN11 is an increasingly prominent predictive biomarker and a molecular sensor for a wide range of clinical drugs: topoisomerases, PARP and replication inhibitors, and platinum derivatives. To expand the spectrum of drugs and pathways targeting SLFN11, we ran a high-throughput screen (HTS) with 1,978 mechanistically-annotated, oncology-focused compounds in two isogenic pairs of SLFN11-proficient and -deficient cells (CCRF-CEM and K562). We identified 29 hit compounds that selectively kill SLFN11-proficient cells, including not only previously known DNA-targeting agents, but also the neddylation inhibitor Pevonedistat (MLN-4924) and the DNA polymerase alpha inhibitor AHPN/CD437, which both induced SLFN11 chromatin recruitment. By inactivating cullin-ring E3 ligases, Pevonedistat acts as an anticancer agent partly by inducing unscheduled re-replication through supra-physiological accumulation of CDT1, an essential factor for replication initiation. Unlike the known DNA-targeting agents and AHPN/CD437 that recruit SLFN11 onto chromatin in 4 hours, Pevonedistat recruited SLFN11 at late time points (24 hours). While Pevonedistat induced unscheduled re-replication in SLFN11-deficient cells after 24 hours, the re-replication was largely blocked in SLFN11-proficient cells. The positive correlation between sensitivity to Pevonedistat and SLFN11 expression was also observed in non-isogenic cancer cells in three independent cancer cell databases (NCI-60, CTRP: Cancer Therapeutics Response Portal and GDSC: Genomic of Drug Sensitivity in Cancer). The present study reveals that, in addition to sensing stressed replication, SLFN11 blocks unscheduled re-replication provoked by Pevonedistat, which augments the anti-cancer effect of Pevonedistat. It also suggests SLFN11 as a potential predictive biomarker for Pevonedistat in ongoing and future clinical trials.

DOI： 10.1158/1535-7163.mct-22-0552

PubMed

researchmap

担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for Cancer Research (AACR)  

Abstract

The concept of “BRCAness” was first described in 2004 to define the situation in which a homologous recombination repair (HRR) defect in a tumor relates to and phenocopies BRCA1 or BRCA2 loss-of-function mutations. Soon after the discovery of synthetic lethality of PARP1/2 inhibitors in BRCA1- or BRCA2-deficient cells, McCabe and colleagues extended the concept of BRCAness to homologous recombination deficiency (HRD) by studying the sensitivity of cancer cells to PARP inhibitors. They genetically revealed that deficiency in HR-related genes (RAD51, RAD54, DSS1, and RPA1), DNA damage signaling genes (ATR, ATM, CHK1, CHK2, and NBS1), or Fanconi anemia–related genes (FANCD2, FANCA, and FANCC) conferred sensitivity to PARP inhibitors. Thus, cells acquire BRCAness either by genetic inactivation of the BRCA or HRD genes. Here, we briefly review how genomic profiling can identify BRCAness and deficiencies in HRD genes and the current difficulty to apply BRCAness/HRD in the clinic. We also discuss how BRCAness relates to HRD and the utility of evaluating BRCAness/HRD to select therapies with PARP inhibitors (olaparib, rucaparib, niraparib, talazoparib, pamiparib, fuzuloparib), topoisomerase I (TOP1) inhibitors (irinotecan, topotecan, and tumor-targeted TOP1 inhibitors), and platinum derivatives (cisplatin and carboplatin).

See related article by McCabe and colleagues, Cancer Res 2006;66:8109–15.

DOI： 10.1158/0008-5472.can-23-0628

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

Recently, Schlafen family member 11 (SLFN11) has been reported to increase the sensitivity of cancer cells to DNA-damaging agents, including platinum derivatives; thus, SLFN11 may be a predictive biomarker for platinum-based chemoradiotherapy (CRT). In this study, we examined whether SLFN11 expression was associated with the therapeutic outcome of platinum-based CRT in head and neck squamous cell carcinoma (HNSCC). We performed immunohistochemical analyses for SLFN11 expression in 161 HNSCC tissues from patients who had been administered cisplatin-based CRT and examined the correlation between SLFN11 expression and progression-free survival (PFS). Additionally, SLFN11 expression was examined in 10 paired samples obtained before and after CRT in patients with local failure. Furthermore, in vitro experiments were performed using several HNSCC cell lines and isogenic SLFN11-knockout cells to assess the association between SLFN11 expression and drug sensitivity. PFS was found to be significantly better in the SLFN11-positive group than in the SLFN11-negative group among the 161 patients (5-year PFS: 78.8% vs. 52.8%, respectively, p < 0.001). Similar results were observed for the PFS at each primary site. The percentage of SLFN11 positivity was lower in tumor samples from patients with local failure after CRT than that in the corresponding primary tumors before CRT in 8 of 10 cases. Results of the in vitro assay demonstrated that SLFN11-knockout cells exhibited reduced sensitivity to DNA-damaging agents but not to the non-DNA-damaging agent docetaxel. Our findings suggest that SLFN11 may serve as a potential biomarker for predicting the response of HNSCC patients to platinum-based CRT.

DOI： 10.3389/fonc.2022.978875

PubMed

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

Abstract

Human cancers often re-express germline factors, yet their mechanistic role in oncogenesis and cancer progression remains unknown. Here we demonstrate that DEAD-box helicase 4 (DDX4), a germline factor and RNA helicase conserved in all multicellular organisms, contributes to increased cell motility and cisplatin-mediated drug resistance in small cell lung cancer (SCLC) cells. Proteomic analysis suggests that DDX4 expression upregulates proteins related to DNA repair and immune/inflammatory response. Consistent with these trends in cell lines, DDX4 depletion compromised in vivo tumor development while its overexpression enhanced tumor growth even after cisplatin treatment in nude mice. Further, the relatively higher DDX4 expression in SCLC patients correlates with decreased survival and shows increased expression of immune/inflammatory response markers. Taken together, we propose that DDX4 increases SCLC cell survival, by increasing the DNA damage and immune response pathways, especially under challenging conditions such as cisplatin treatment.

DOI： 10.1038/s42003-023-04444-7

researchmap

その他リンク： https://www.nature.com/articles/s42003-023-04444-7

掲載種別：研究論文（学術雑誌）  

DOI： 10.7554/eLife.83870

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Intensive chemotherapeutic regimens with craniospinal irradiation have greatly improved survival in medulloblastoma patients. However, survival markedly differs among molecular subgroups and their biomarkers are unknown. Through unbiased screening, we found Schlafen family member 11 (SLFN11), which is known to improve response to DNA damaging agents in various cancers, to be one of the top prognostic markers in medulloblastomas. Hence, we explored the expression and functions of SLFN11 in medulloblastoma. METHODS: SLFN11 expression for each subgroup was assessed by immunohistochemistry in 98 medulloblastoma patient samples and by analyzing transcriptomic databases. We genetically or epigenetically modulated SLFN11 expression in medulloblastoma cell lines and determined cytotoxic response to the DNA damaging agents cisplatin and topoisomerase I inhibitor SN-38 in vitro and in vivo. RESULTS: High SLFN11 expressing cases exhibited significantly longer survival than low expressing cases. SLFN11 was highly expressed in the WNT-activated subgroup and in a proportion of the SHH-activated subgroup. While WNT activation was not a direct cause of the high expression of SLFN11, a specific hypomethylation locus on the SLFN11 promoter was significantly correlated with high SLFN11 expression. Overexpression or deletion of SLFN11 made medulloblastoma cells sensitive and resistant to cisplatin and SN-38, respectively. Pharmacological upregulation of SLFN11 by the brain-penetrant histone deacetylase-inhibitor RG2833 markedly increased sensitivity to cisplatin and SN-38 in SLFN11-negative medulloblastoma cells. Intracranial xenograft studies also showed marked sensitivity to cisplatin by SLFN11-overexpression in medulloblastoma cells. CONCLUSIONS: High SLFN11 expression is one factor which renders favorable outcomes in WNT-activated and a subset of SHH-activated medulloblastoma possibly through enhancing response to cisplatin.

DOI： 10.1093/neuonc/noac243

PubMed

researchmap

記述言語：英語  

BACKGROUND: Primary central nervous system lymphomas (PCNSLs) are sensitive to chemotherapy. The standard treatment is high-dose methotrexate (MTX)-based chemotherapy. There are no reports of successful treatment of acute uric acid nephropathy with rasburicase after MTX administration in PCNSLs. CASE PRESENTATION: A 54-year-old man with a history of gout presented with a change in character and cognitive dysfunction. MRI showed a large enhancing mass spanning the bilateral frontal lobes and the right temporal lobe. After endoscopic biopsy, an MTX, procarbazine, and vincristine (MPV) regimen was initiated for the treatment of the PCNSL. After the initiation of chemotherapy, the patient experienced a gout attack, and blood examination revealed acute renal failure (ARF) and hyperuricemia. The considered causes of ARF included MTX toxicity and acute uric acid nephropathy. As the dramatic effect of MTX was observed, treatment was continued despite ARF, most probably due to acute hyperuricemia due to tumor lysis, which was treated in parallel. After an improvement in renal function, MTX was resumed, and rasburicase was initiated to control hyperuricemia. A complete response was obtained after induction chemotherapy. Hyperuricemia was controlled with rasburicase, and renal function was preserved. CONCLUSIONS: Acute uric acid nephropathy should be considered when ARF occurs after the initiation of MTX in PCNSLs, especially in newly diagnosed PCNSL patients with large tumors or hyperuricemia.

DOI： 10.3390/jcm11195548

PubMed

researchmap

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

PARP inhibitors (PARPis) were initially developed as DNA repair inhibitors that inhibit the catalytic activity of PARP1 and PARP2 and are expected to induce synthetic lethality in BRCA- or homologous recombination (HR)-deficient tumors. However, the clinical indications for PARPis are not necessarily limited to BRCA mutations or HR deficiency; BRCA wild-type and HR-proficient cancers can also derive some benefit from PARPis. These facts are interpretable by an additional primary antitumor mechanism of PARPis named PARP trapping, resulting from the stabilization of PARP-DNA complexes. Favorable response to platinum derivatives (cisplatin and carboplatin) in preceding treatment is used as a clinical biomarker for some PARPis, implying that sensitivity factors for platinum derivatives and PARPis are mainly common. Such common sensitivity factors include not only HR defects (HRD) but also additional factors. One of them is Schlafen 11 (SLFN11), a putative DNA/RNA helicase, that sensitizes cancer cells to a broad type of DNA-damaging agents, including platinum and topoisomerase inhibitors. Mechanistically, SLFN11 induces a lethal replication block in response to replication stress (ie, DNA damage). As SLFN11 acts upon replication stress, trapping PARPis can activate SLFN11. Preclinical models show the importance of SLFN11 in PARPi sensitivity. However, the relevance of SLFN11 in PARPi response is less evident in clinical data compared with the significance of SLFN11 for platinum sensitivity. In this review, we consider the reasons for variable indications of PARPis resulting from clinical outcomes and review the mechanisms of action for PARPis as anticancer agents.

DOI： 10.1111/cas.15477

PubMed

researchmap

記述言語：英語   出版者・発行元：(一社)日本癌学会  

researchmap

記述言語：日本語   出版者・発行元：新潟医学会  

researchmap

記述言語：日本語   出版者・発行元：日本脳腫瘍病理学会  

researchmap

記述言語：日本語   出版者・発行元：(一社)日本小児神経外科学会  

researchmap

記述言語：日本語   出版者・発行元：(一社)日本小児神経外科学会  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The utility of Schlafen 11 (SLFN11) expression as a predictive biomarker for platinum-based chemotherapy has been established for cancers from different histologies. However, the therapeutic relevance of SLFN11 in bladder cancer (BC) is unknown. Here, we examined the clinicopathologic significance of SLFN11 expression across 120 BC cases by immunohistochemistry. We divided the cases into two cohorts, one including 50 patients who received adjuvant or neoadjuvant platinum-based chemotherapy, and the other including 70 BC patients treated by surgical resection without chemotherapy. In the cohort of 50 BC cases treated with platinum-based chemotherapy, the SLFN11-positive group (n = 25) showed significantly better overall survival than the SLFN11-negative group (n = 25, P = .012). Schlafen 11 expression correlated significantly with the expression of luminal subtype marker GATA3. Multivariate analyses identified SLFN11 expression as an independent prognostic predictor (odds ratio, 0.32; 95% confidence interval, 0.11-0.91; P = .033). Conversely, in the cohort of 70 BC cases not receiving platinum-based chemotherapy, the SLFN11-positive group (n = 29) showed significantly worse overall survival than the SLFN11-negative group (n = 41, P = .034). In vitro analyses using multiple BC cell lines confirmed that SLFN11 KO rendered cells resistant to cisplatin. The epigenetic modifying drugs 5-azacytidine and entinostat restored SLFN11 expression and resensitized cells to cisplatin and carboplatin in SLFN11-negative BC cell lines. We conclude that SLFN11 is a predictive biomarker for BC patients who undergo platinum-based chemotherapy and that the combination of epigenetic modifiers could rescue refractory BC patients to platinum derivatives by reactivating SLFN11 expression.

DOI： 10.1111/cas.15207

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

Schlafen11 (SLFN11) is referred to as interferon (IFN)-inducible. Based on cancer genomic databases, we identified human acute myeloid and lymphoblastic leukemia cells with gain-of-function mutations in the Janus kinase (JAK) family as exhibiting high SLFN11 expression. In these cells, the clinical JAK inhibitors cerdulatinib, ruxolitinib, and tofacitinib reduced SLFN11 expression, but IFN did not further induce SLFN11 despite phosphorylated STAT1. We provide evidence that suppression of SLFN11 by JAK inhibitors is caused by inactivation of the non-canonical IFN pathway controlled by AKT and ERK. Accordingly, the AKT and ERK inhibitors MK-2206 and SCH77284 suppressed SLFN11 expression. Both also suppressed the E26 transformation-specific (ETS)-family genes ETS-1 and FLI-1 that act as transcription factors for SLFN11. Moreover, SLFN11 expression was inhibited by the ETS inhibitor TK216. Our study reveals that SLFN11 expression is regulated via the JAK, AKT and ERK, and ETS axis. Pharmacological suppression of SLFN11 warrants future studies.

DOI： 10.1016/j.isci.2021.103173

PubMed

researchmap

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Although unresectable or recurrent gastric cancers (GC) are frequently treated with platinum-based chemotherapy, response to treatment remains unpredictable. Because Schlafen 11 (SLFN11) is recently identified as a critical determinant of platinum sensitivity, we investigated the potential clinical utility of SLFN11 in the treatment of GC. METHODS: We analysed the correlation between SLFN11 expression and overall survival in 169 GC patients by our established immunohistochemical approach. The impact of SLFN11 expression on the response to platinum and transition of SLFN11 expression upon long-term treatment with platinum were examined using GC cell lines and organoids. RESULTS: GC patients with high-SLFN11 expression exhibited significantly better survival than those with low-SLFN11 expression, and the significance increased when we selected patients treated with platinum-based chemotherapy. Knockout of SLFN11 and reactivation of SLFN11 in GC cells conferred resistance and sensitivity to platinum, respectively. In GC cells and organoids, long-term treatment with oxaliplatin suppressed SLFN11 expression while imparting drug resistance. The acquired resistance to oxaliplatin was reversed by reactivation of SLFN11 with epigenetic modifying drugs. CONCLUSIONS: This is the first report revealing definitive clinical implications of SLFN11 in the treatment of GC patients and providing novel strategies for the drug selection based on SLFN11 expression.

DOI： 10.1038/s41416-021-01364-3

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for Cancer Research (AACR)  

Schlafen11 (SLFN11) inactivation occurs in approximately 50% of cancer cell lines and in a large fraction of patient tumor samples, which leads to chemoresistance. Therefore, new therapeutic approaches are needed to target SLFN11-deficient cancers. To that effect, we conducted a drug screen with the NCATS mechanistic drug library of 1,978 compounds in isogenic SLFN11-knockout (KO) and wild-type (WT) leukemia cell lines. Here we report that TAK-243, a first-in-class ubiquitin activating enzyme UBA1 inhibitor in clinical development, causes preferential cytotoxicity in SLFN11-KO cells; this effect is associated with claspin-mediated DNA replication inhibition by CHK1 independently of ATR. Additional analyses showed that SLFN11-KO cells exhibit consistently enhanced global protein ubiquitylation, endoplasmic reticulum (ER) stress, unfolded protein response (UPR), and protein aggregation. TAK-243 suppressed global protein ubiquitylation and activated the UPR transducers PERK, phosphorylated eIF2α, phosphorylated IRE1, and ATF6 more effectively in SLFN11-KO cells than in WT cells. Proteomic analysis using biotinylated mass spectrometry and RNAi screening also showed physical and functional interactions of SLFN11 with translation initiation complexes and protein folding machinery. These findings uncover a previously unknown function of SLFN11 as a regulator of protein quality control and attenuator of ER stress and UPR. Moreover, they suggest the potential value of TAK-243 in SLFN11-deficient tumors. SIGNIFICANCE: This study uncovers that SLFN11 deficiency induces proteotoxic stress and sensitizes cancer cells to TAK-243, suggesting that profiling SLFN11 status can serve as a therapeutic biomarker for cancer therapy.

DOI： 10.1158/0008-5472.can-20-2694

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Schlafen-11 (SLFN11) inactivation in ∼50% of cancer cells confers broad chemoresistance. To identify therapeutic targets and underlying molecular mechanisms for overcoming chemoresistance, we performed an unbiased genome-wide RNAi screen in SLFN11-WT and -knockout (KO) cells. We found that inactivation of Ataxia Telangiectasia- and Rad3-related (ATR), CHK1, BRCA2, and RPA1 overcome chemoresistance to camptothecin (CPT) in SLFN11-KO cells. Accordingly, we validate that clinical inhibitors of ATR (M4344 and M6620) and CHK1 (SRA737) resensitize SLFN11-KO cells to topotecan, indotecan, etoposide, cisplatin, and talazoparib. We uncover that ATR inhibition significantly increases mitotic defects along with increased CDT1 phosphorylation, which destabilizes kinetochore-microtubule attachments in SLFN11-KO cells. We also reveal a chemoresistance mechanism by which CDT1 degradation is retarded, eventually inducing replication reactivation under DNA damage in SLFN11-KO cells. In contrast, in SLFN11-expressing cells, SLFN11 promotes the degradation of CDT1 in response to CPT by binding to DDB1 of CUL4CDT2 E3 ubiquitin ligase associated with replication forks. We show that the C terminus and ATPase domain of SLFN11 are required for DDB1 binding and CDT1 degradation. Furthermore, we identify a therapy-relevant ATPase mutant (E669K) of the SLFN11 gene in human TCGA and show that the mutant contributes to chemoresistance and retarded CDT1 degradation. Taken together, our study reveals new chemotherapeutic insights on how targeting the ATR pathway overcomes chemoresistance of SLFN11-deficient cancers. It also demonstrates that SLFN11 irreversibly arrests replication by degrading CDT1 through the DDB1-CUL4CDT2 ubiquitin ligase.

DOI： 10.1073/pnas.2015654118

PubMed

researchmap

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: SLFN11 has recently been reported to execute cancer cells harboring replicative stress induced by DNA damaging agents. However, the roles of SLFN11 under physiological conditions remain poorly understood. Germinal center B-cells (GCBs) undergo somatic hypermutations and class-switch recombination, which can cause physiological genotoxic stress. Hence, we tested whether SLFN11 expression needs to be suppressed in GCBs during B-cell development. OBJECTIVE: To clarify the expression profile of SLFN11 in different developmental stages of B-cells and B-cell-derived cancers. METHODS: We analyzed the expression of SLFN11 by mining cell line databases for different stages of normal B-cells and various types of B-cell-derived cancer cell lines. We performed dual immunohistochemical staining for SLFN11 and B-cell specific markers in normal human lymphatic tissues. We tested the effects of two epigenetic modifiers, an EZH2 inhibitor, tazemetostat (EPZ6438) and a histone deacetylase inhibitor, panobinostat (LBH589) on SLFN11 expression in GCB-derived lymphoma cell lines. We also examined the therapeutic efficacy of these drugs in combination with cytosine arabinoside and the effects of SLFN11 on the efficacy of cytosine arabinoside in SLFN11-overexpressing cells. RESULTS: SLFN11 mRNA level was found low in both normal GCBs and GCB-DLBCL (GCB like-diffuse large B-cell lymphoma). Immunohistochemical staining showed low SLFN11 expression in GCBs and high SLFN11 expression in plasmablasts and plasmacytes. The EZH2 and HDAC epigenetic modifiers upregulated SLFN11 expression in GCB-derived lymphoma cells and made them more susceptible to cytosine arabinoside. SLFN11 overexpression further sensitized GCB-derived lymphoma cells to cytosine arabinoside. CONCLUSIONS: The expression of SLFN11 is epigenetically suppressed in normal GCBs and GCB-derived lymphomas. GCB-derived lymphomas with low SLFN11 expression can be treated by the combination of epigenetic modifiers and cytosine arabinoside.

DOI： 10.1371/journal.pone.0237554

PubMed

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-021-92948-9

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Schlafen 11 (SLFN11) was recently identified as a dominant determinant of sensitivity to DNA-targeting agents including platinum-based drugs. SLFN11 also reportedly enhances cellular radiosensitivity. In this study, we examined the prognostic value of SLFN11 expression in esophageal squamous cell carcinoma (ESCC) patients treated with definitive chemoradiotherapy (dCRT), including the platinum derivative nedaplatin. METHODS: Seventy-three patients with ESCC who received dCRT were examined. SLFN11 expression was analyzed in pre-dCRT biopsies using immunohistochemistry and evaluated using a histo-score (H-score). Correlation between the H-score and overall survival was analyzed. An H-score ≥ 51 was provisionally defined as indicating high SLFN11 expression. Viability assays were performed using previously established isogenic human cell lines differentially expressing SLFN11 to test the usefulness of SLFN11 as marker of response to the dCRT regimen. RESULTS: High SLFN11 expression was independently associated with better prognosis in ESCC patients (hazard ratio = 0.295, 95% CI = 0.143-0.605, p = 0.001 for multivariate analysis). Kaplan-Meier survival curves showed that the prognostic value of high SLFN11 expression was most evident in patients at clinical stages II and III (p = 0.004). In in vitro study, SLFN11-proficient cells were highly sensitive to platinum derivatives compared to SLFN11-deficient cells. CONCLUSION: SLFN11 expression is an independent prognostic factor for ESCC patients treated with dCRT and a potential biomarker for treatment selection of ESCC. Examination of SLFN11 may be particularly useful for clinical Stage II-III patients who wish to choose dCRT (instead of surgery) to preserve esophageal function.

DOI： 10.1186/s12885-020-07574-x

PubMed

researchmap

記述言語：英語   出版者・発行元：(一社)日本癌学会  

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：American Association for Cancer Research  

DOI： 10.1158/1538-7445.am2020-lb-121

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

High grade serous ovarian cancer (HGSOC) is a fatal gynecologic malignancy in the U.S. with limited treatment options. New therapeutic strategies include targeting of the cell cycle checkpoints, e.g., ATR and CHK1. We recently reported a promising clinical activity of the CHK1 inhibitor (CHK1i) prexasertib monotherapy in BRCA wild-type (BRCAwt) HGSOC patients. In this study, biopsies of treated patients and cell line models were used to investigate possible mechanisms of resistance to CHK1i. We report that BRCAwt HGSOC develops resistance to prexasertib monotherapy via a prolonged G2 delay induced by lower CDK1/CyclinB1 activity, thus preventing cells from mitotic catastrophe and cell death. On the other hand, we noted CHK1's regulation on RAD51-mediated homologous recombination (HR) repair was not altered in CHK1i-resistant cells. Therefore, CHK1i sensitizes CHK1i-resistant cells to DNA damaging agents such as gemcitabine or hydroxyurea by inhibition of HR. In summary, our results demonstrate new mechanistic insights of functionally distinct CHK1 activities and highlight a potential combination treatment approach to overcome CHK1i resistance in BRCAwt HGSOC.

DOI： 10.1038/s41388-020-1383-4

PubMed

researchmap

記述言語：英語  

DOI： 10.1016/j.jtho.2020.03.033

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DNA-damaging agents include first-line drugs such as platinum (cisplatin, carboplatin), topoisomerase inhibitors (etoposide, doxorubicin), and replication inhibitors (cytarabine, gemcitabine). Despite their wide and long usage, there is no clinically available biomarker to predict responses to these drugs. Schlafen 11 (SLFN11), a putative DNA/RNA helicase, recently emerged as a dominant determinant of sensitivity to these drugs by enforcing the replication block in response to DNA damage. Since the clinical importance of SLFN11 is implicated, a comprehensive analysis of SLFN11 expression across human organs will provide a practical resource to develop the utility of SLFN11 in the clinic. In this study, we established a scoring system of SLFN11 expression by immunohistochemistry (IHC) and assessed SLFN11 expression in ~ 700 malignant as well as the adjacent non-tumor tissues across 16 major human adult organs. We found that the SLFN11 expression is tissue specific and varies during tumorigenesis. Although The Cancer Genome Atlas (TCGA) is a prevailing tool to assess gene expression in various malignant and normal tissues, our IHC data exhibited obvious discrepancy from the TCGA data in several organs. Importantly, SLFN11-negative tumors, potentially non-responders to DNA-damaging agents, were largely overrated in TCGA because TCGA samples are a mixture of infiltrating immune cells, including T cells, B cells, and macrophages, which have strong SLFN11 expression. Thus, our study reveals the significance of immunohistochemical procedures for evaluating expression of SLFN11 in patient samples and provides a robust resource of SLFN11 expression across adult human organs.

DOI： 10.1007/s00428-020-02840-6

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

INTRODUCTION: BRCA1-associated protein-1 (BAP1), a nuclear deubiquitinase thought to be involved in DNA double-strand break repair, is frequently mutated in mesothelioma. Because poly(adenosine diphosphate-ribose) polymerase inhibitors (PARPIs) induce synthetic lethality in BRCA1/2 mutant cancers, we evaluated whether BAP1 inactivating mutations confer sensitivity to PARPIs in mesothelioma and if combination therapy with temozolomide (TMZ) would be beneficial. METHODS: A total of 10 patient-derived mesothelioma cell lines were generated and characterized for BAP1 mutation status, protein expression, nuclear localization, and sensitivity to the PARPIs, olaparib, and talazoparib, alone or in combination with TMZ. BAP1 deubiquitinase (DUB) activity was evaluated by ubiquitin with 7-amido-4-methylcoumarin assay. BAP1 knockout mesothelioma cell lines were generated by CRISPR-Cas9. Because Schlafen 11 (SLFN11) and O6-methylguanine-DNA methyltransferase also drive response to TMZ and PARPIs, we tested their expression and relationship with drug response. RESULTS: BAP1 mutations or copy-number alterations, or both were present in all 10 cell lines. Nonetheless, four cell lines exhibited intact DUB activity and two had nuclear BAP1 localization. Half maximal-inhibitory concentrations of olaparib and talazoparib ranged from 4.8 μM to greater than 50 μM and 0.039 μM to greater than 5 μM, respectively, classifying them into sensitive (two) or resistant (seven) cells, independent of their BAP1 status. Cell lines with BAP1 knockout resulted in the loss of BAP1 DUB activity but did not increase sensitivity to talazoparib. Response to PARPI tended to be associated with high SLFN11 expression, and combination with temozolomide increased sensitivity of cells with low or no MGMT expression. CONCLUSIONS: BAP1 status does not determine sensitivity to PARPIs in patient-derived mesothelioma cell lines. Combination of PARPI with TMZ may be beneficial for patients whose tumors have high SLFN11 and low or no MGMT expression.

DOI： 10.1016/j.jtho.2020.01.012

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: Next-generation sequencing allows genome-wide analysis of changes in chromatin states and gene expression. Data analysis of these increasingly used methods either requires multiple analysis steps, or extensive computational time. We sought to develop a tool for rapid quantification of sequencing peaks from diverse experimental sources and an efficient method to produce coverage tracks for accurate visualization that can be intuitively displayed and interpreted by experimentalists with minimal bioinformatics background. We demonstrate its strength and usability by integrating data from several types of sequencing approaches. RESULTS: We have developed BAMscale, a one-step tool that processes a wide set of sequencing datasets. To demonstrate the usefulness of BAMscale, we analyzed multiple sequencing datasets from chromatin immunoprecipitation sequencing data (ChIP-seq), chromatin state change data (assay for transposase-accessible chromatin using sequencing: ATAC-seq, DNA double-strand break mapping sequencing: END-seq), DNA replication data (Okazaki fragments sequencing: OK-seq, nascent-strand sequencing: NS-seq, single-cell replication timing sequencing: scRepli-seq) and RNA-seq data. The outputs consist of raw and normalized peak scores (multiple normalizations) in text format and scaled bigWig coverage tracks that are directly accessible to data visualization programs. BAMScale also includes a visualization module facilitating direct, on-demand quantitative peak comparisons that can be used by experimentalists. Our tool can effectively analyze large sequencing datasets (~ 100 Gb size) in minutes, outperforming currently available tools. CONCLUSIONS: BAMscale accurately quantifies and normalizes identified peaks directly from BAM files, and creates coverage tracks for visualization in genome browsers. BAMScale can be implemented for a wide set of methods for calculating coverage tracks, including ChIP-seq and ATAC-seq, as well as methods that currently require specialized, separate tools for analyses, such as splice-aware RNA-seq, END-seq and OK-seq for which no dedicated software is available. BAMscale is freely available on github (https://github.com/ncbi/BAMscale).

DOI： 10.1186/s13072-020-00343-x

PubMed

researchmap

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Schlafen 11 (SLFN11) was recently discovered as a cellular restriction factor against replication stress. Here, we show that SLFN11 increases chromatin accessibility genome wide, prominently at active promoters in response to replication stress induced by the checkpoint kinase 1 (CHK1) inhibitor prexasertib or the topoisomerase I (TOP1) inhibitor camptothecin. Concomitantly, SLFN11 selectively activates cellular stress response pathways by inducing the transcription of the immediate early genes (IEGs), including JUN, FOS, EGR1, NFKB2, and ATF3, together with the cell cycle arrest genes CDKN1A (p21WAF1) and GADD45. Both chromatin remodeling and IEG activation require the putative ATPase and helicase activity of SLFN11, whereas canonical extrinsic IEG activation is SLFN11 independent. SLFN11-dependent IEG activation by camptothecin is also observed across 55 non-isogenic NCI-60 cell lines. We conclude that SLFN11 acts as a global regulator of chromatin structure and an intrinsic IEG activator with the potential to engage the innate immune activation in response to replicative stress.

DOI： 10.1016/j.celrep.2020.02.117

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

PURPOSE: Irinotecan and topotecan are used to treat a variety of different cancers. However, they have limitations, including chemical instability and severe side effects. To overcome these limitations, we developed the clinical indenoisoquinolines: LMP400 (indotecan), LMP776 (indimitecan), and LMP744. The purpose of the study is to build the molecular rationale for phase II clinical trials. EXPERIMENTAL DESIGN: CellMinerCDB (http://discover.nci.nih.gov/cellminercdb) was used to mine the cancer cell lines genomic databases. The causality of Schlafen11 (SLFN11) was validated in isogenic cell lines. Because topoisomerase I (TOP1)-mediated replication DNA damage is repaired by homologous recombination (HR), we tested the "synthetic lethality" of HR-deficient (HRD) cells. Survival and cell-cycle alterations were performed after drug treatments in isogenic DT40, DLD1, and OVCAR cell lines with BRCA1, BRCA2, or PALB2 deficiencies and in organoids cultured from prostate cancer patient-derived xenografts with BRCA2 loss. We also used an ovarian orthotopic allograft model with BRCA1 loss to validate the efficacy of LMP400 and olaparib combination. RESULTS: CellMinerCDB reveals that SLFN11, which kills cells undergoing replicative stress, is a dominant drug determinant to the clinical indenoisoquinolines. In addition, BRCA1-, BRCA2-, and PALB2-deficient cells were hypersensitive to the indenoisoquinolines. All 3 clinical indenoisoquinolines were also synergistic with olaparib, especially in the HRD cells. The synergy between LMP400 and olaparib was confirmed in the orthotopic allograft model harboring BRCA1 loss. CONCLUSIONS: Our results provide a rationale for molecularly designed clinical trials with the indenoisoquinolines as single agents and in combination with PARP inhibitors in HRD cancers expressing SLFN11.

DOI： 10.1158/1078-0432.CCR-19-0419

PubMed

researchmap

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Schlafen 11 (SLFN11) sensitizes cells to a broad range of anti-cancer drugs including platinum derivatives (cisplatin and carboplatin), inhibitors of topoisomerases (irinotecan, topotecan, doxorubicin, daunorubicin, mitoxantrone and etoposide), DNA synthesis inhibitors (gemcitabine, cytarabine, hydroxyurea and nucleoside analogues), and poly(ADPribose) polymerase (PARP) inhibitors (olaparib, rucaparib, niraparib and talazoparib). In spite of their different primary mechanisms of action, all these drugs damage DNA during S-phase, activate the intra-S-phase checkpoint and induce replication fork slowing and stalling with single-stranded DNA segments coated with replication protein A. Such situation with abnormal replication forks is known as replication stress. SLFN11 irreversibly blocks replication in cells under replication stress, explaining why SLFN11-positive cells are markedly more efficiently killed by DNA-targeting drugs than SLFN11-negative cells. SLFN11 is inactivated in ~50% of cancer cell lines and in a large fraction of tumors, and is linked with the native immune, interferon and T-cells responses, implying the translational relevance of measuring SLFN11 expression as a predictive biomarker of response and resistance in patients. SLFN11 is also a plausible epigenetic target for reactivation by inhibitors of histone deacetylases (HDAC), DNA methyltransferases (DNMT) and EZH2 histone methyltransferase and for combination of these epigenetic inhibitors with DNA-targeting drugs in cells lacking SLFN11 expression. In addition, resistance due to lack of SLFN11 expression in tumors is a potential indication for cell-cycle checkpoint inhibitors in combination with DNA-targeting therapies.

DOI： 10.1016/j.pharmthera.2019.05.009

PubMed

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

There is extensive literature on PARP1, owing to the multiple functions of PARP1 for DNA repair, aging, chromatin remodeling and transcription, and to the successful clinical development of four PARP inhibitors. In this issue of Cancer Research, Wang and colleagues identified phosphatase 1 nuclear targeting subunit (PNUTS, also referred to as PP1R10) as a partner of PARP1 and demonstrated that PNUTS and PARP1 are interdependent for their recruitment to DNA damage sites. As PARP1 is a prominent target for cancer therapy and PNUTS has PARP-dependent as well as PARP1-independent activities, the findings of Wang and colleagues add insight into DNA repair mechanisms with potential application to drug targeting and precision therapy.See related article by Wang et al., p. 2526.

DOI： 10.1158/0008-5472.CAN-19-0798

PubMed

researchmap

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ANNUAL REVIEWS  

Poly(ADP-ribose) polymerase inhibitors (PARPis) have recently been approved for the treatment of ovarian and breast cancers with BRCA mutations, as well as for maintenance therapies regardless of BRCA mutation for ovarian and primary peritoneal cancers that previously responded to platinum-based chemotherapy. The rationale of these indications is derived from the facts that cancer cells with BRCA mutations are defective in homologous recombination (HR), which confers synthetic lethality with PARPis, and that some of the sensitivity-determining factors for PARPis are shared with platinums. Although BRCA1 and BRCA2 are central for HR, more players within and beyond HR are emerging as response determinants to PARPis. Furthermore, there are similarities as well as differences in the DNA lesions and repair pathways induced by PARPis, platinums, and camptothecin topoisomerase 1 (TOP1) inhibitors. Here we review the sensitivity-determining factors for PARPis and the rationale for using PARPis as single agents and in combination therapy for cancers.

DOI： 10.1146/annurev-cancerbio-030518-055914

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Poly(ADP-ribose) polymerase (PARP) inhibition serves as a potent therapeutic option eliciting synthetic lethality in cancers harboring homologous recombination (HR) repair defects, such as BRCA mutations. However, the development of resistance to PARP inhibitors (PARPis) poses a clinical challenge. Restoration of HR competency is one of the many molecular factors contributing to PARPi resistance. Combination therapy with cell cycle checkpoint (ATR, CHK1, and WEE1) inhibitors is being investigated clinically in many cancers, particularly in ovarian cancer, to enhance the efficacy and circumvent resistance to PARPis. Ideally, inhibition of ATR, CHK1 and WEE1 proteins will abrogate G2 arrest and subsequent DNA repair via restored HR in PARPi-treated cells. Replication fork stabilization has recently been identified as a potential compensatory PARPi resistance mechanism, found in the absence of restored HR. ATR, CHK1, and WEE1 each possess different roles in replication fork stabilization, providing different mechanisms to consider when developing combination therapies to avoid continued development of drug resistance. This review examines the impact of ATR, CHK1, and WEE1 on replication fork stabilization. We also address the therapeutic potential for combining PARPis with cell cycle inhibitors and the possible consequence of combination therapies which do not adequately address both restored HR and replication fork stabilization as PARPi resistance mechanisms.

DOI： 10.1016/j.ctrv.2018.09.003

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Contrary to other anticancer targets, topoisomerase I (TOP1) is targeted by only one chemical class of FDA-approved drugs: topotecan and irinotecan, the derivatives of the plant alkaloid, camptothecin. The indenoisoquinolines LMP400, LMP744, and LMP776 are novel noncamptothecin TOP1 inhibitors in clinical trial, which overcome the limitations of camptothecins. To further improve metabolic stability, their methoxy groups have been replaced by fluorine, as in the fluoroindenoisoquinolines NSC 781517 (LMP517), NSC 779135 (LMP135), and NSC 779134 (LMP134). We tested the induction and stability of TOP1 cleavage complexes (TOP1cc), and the induction and persistence of DNA damage measured by histone H2AX phosphorylation (γH2AX) compared with their parent compounds LMP744 and LMP776 in leukemia CCRF-CEM and colon carcinoma HCT116 cells. The fluoroindenoisoquinolines induced TOP1cc and γH2AX at nanomolar concentrations, and at higher levels than the parent indenoisoquinolines. The fluoroindenoisoquinoline LMP135 showed greater antitumor activity than topotecan in small-cell lung cancer cell H82 xenografts. It was also more potent than topotecan in the NCI-60 cancer cell line panel. Bioinformatics tools (http://discover.nci.nih.gov/cellminercdb) were used to investigate the following: (i) the correlations of fluoroindenoisoquinolines activity with other drugs, and (ii) genomic determinants of response in the NCI-60. The activity of the fluoroindenoisoquinolines was mostly correlated with camptothecin derivatives and the parent indenoisoquinolines, consistent with TOP1 targeting. Genomic analyses and activity assays in CCRF-CEM SLFN11-deleted cells showed that SLFN11 expression is a dominant determinant of response to LMP135. This study shows the potential value of the fluoroindenoisoquinolines for further development as novel anticancer agents targeting TOP1. Mol Cancer Ther; 17(8); 1694-704. ©2018 AACR.

DOI： 10.1158/1535-7163.MCT-18-0028

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Poly(ADP-ribose) polymerase inhibitors (PARPis) are DNA-damaging agents that trap PARP-DNA complexes and interfere with DNA replication. Three PARPis - olaparib, niraparib, and rucaparib - were recently approved by the FDA for the treatment of breast and ovarian cancers. These PARPis, along with 2 others (talazoparib and veliparib), are being evaluated for their potential to treat additional malignancies, including prostate cancers. While lack of PARP-1 confers high resistance to PARPis, it has not been established whether or not the levels of PARP-1 directly correlate with tumor response. In this issue of the JCI, Makvandi and coworkers describe an approach to address this question using [18F]FluorThanatrace, an [18F]-labeled PARP-1 inhibitor, for PET. The tracer was taken up by patient tumor tissue and appeared to differentiate levels of PARP-1 expression; however, future studies should be aimed at determining if this tracer can be used to stratify patient response to PARPi therapy.

DOI： 10.1172/JCI120388

PubMed

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Purpose: Schlafen 11 (SLFN11), a putative DNA/RNA helicase is a dominant genomic determinant of response to DNA-damaging agents and is frequently not expressed in cancer cells. Whether histone deacetylase (HDAC) inhibitors can be used to release SLFN11 and sensitize SLFN11-inactivated cancers to DNA-targeted agents is tested here.Experimental Design:SLFN11 expression was examined in The Cancer Genome Atlas (TCGA), in cancer cell line databases and in patients treated with romidepsin. Isogenic cells overexpressing or genetically inactivated for SLFN11 were used to investigate the effect of HDAC inhibitors on SLFN11 expression and sensitivity to DNA-damaging agents.Results:SLFN11 expression is suppressed in a broad fraction of common cancers and cancer cell lines. In cancer cells not expressing SLFN11, transfection of SLFN11 sensitized the cells to camptothecin, topotecan, hydroxyurea, and cisplatin but not to paclitaxel. SLFN11 mRNA and protein levels were strongly induced by class I (romidepsin, entinostat), but not class II (roclinostat) HDAC inhibitors in a broad panel of cancer cells. SLFN11 expression was also enhanced in peripheral blood mononuclear cells of patients with circulating cutaneous T-cell lymphoma treated with romidepsin. Consistent with the epigenetic regulation of SLFN11, camptothecin and class I HDAC inhibitors were synergistic in many of the cell lines tested.Conclusions: This study reports the prevalent epigenetic regulation of SLFN11 and the dominant stimulatory effect of HDAC inhibitors on SLFN11 expression. Our results provide a rationale for combining class I HDAC inhibitors and DNA-damaging agents to overcome epigenetic inactivation of SLFN11-mediated resistance to DNA-targeted agents. Clin Cancer Res; 24(8); 1944-53. ©2018 AACR.

DOI： 10.1158/1078-0432.CCR-17-0443

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Tyrosyl-DNA phosphodiesterase 2 (TDP2) repairs abortive topoisomerase II cleavage complexes. Here, we identify a novel short isoform of TDP2 (TDP2S) expressed from an alternative transcription start site. TDP2S contains a mitochondrial targeting sequence, contributing to its enrichment in the mitochondria and cytosol, while full-length TDP2 contains a nuclear localization signal and the ubiquitin-associated domain in the N-terminus. Our study reveals that both TDP2 isoforms are present and active in the mitochondria. Comparison of isogenic wild-type (WT) and TDP2 knockout (TDP2-/-/-) DT40 cells shows that TDP2-/-/- cells are hypersensitive to mitochondrial-targeted doxorubicin (mtDox), and that complementing TDP2-/-/- cells with human TDP2 restores resistance to mtDox. Furthermore, mtDox selectively depletes mitochondrial DNA in TDP2-/-/- cells. Using CRISPR-engineered human cells expressing only the TDP2S isoform, we show that TDP2S also protects human cells against mtDox. Finally, lack of TDP2 in the mitochondria reduces the mitochondria transcription levels in two different human cell lines. In addition to identifying a novel TDP2S isoform, our report demonstrates the presence and importance of both TDP2 isoforms in the mitochondria.

DOI： 10.15252/embr.201642139

PubMed

researchmap

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

SLFN11 sensitizes cancer cells to a broad range of DNA-targeted therapies. Here we show that, in response to replication stress induced by camptothecin, SLFN11 tightly binds chromatin at stressed replication foci via RPA1 together with the replication helicase subunit MCM3. Unlike ATR, SLFN11 neither interferes with the loading of CDC45 and PCNA nor inhibits the initiation of DNA replication but selectively blocks fork progression while inducing chromatin opening across replication initiation sites. The ATPase domain of SLFN11 is required for chromatin opening, replication block, and cell death but not for the tight binding of SLFN11 to chromatin. Replication stress by the CHK1 inhibitor Prexasertib also recruits SLFN11 to nascent replicating DNA together with CDC45 and PCNA. We conclude that SLFN11 is recruited to stressed replication forks carrying extended RPA filaments where it blocks replication by changing chromatin structure across replication sites.

DOI： 10.1016/j.molcel.2018.01.012

PubMed

researchmap

記述言語：英語  

SLFN11 is a recently discovered protein with a putative DNA/RNA helicase function. First identified in association with the maturation of thymocytes, SLFN11 was later causally associated, by two independent groups, with the resistance to DNA damaging agents such as topoisomerase I and II inhibitors, platinum compounds, and other alkylators, making it an attractive molecule for biomarker development. Later, SLFN11 was linked to antiviral response in human cells and interferon production, establishing a potential bond between immunity and chemotherapy. Recently, we demonstrated the potential role of SLN11 as a biomarker to predict sensitivity to the carboplatin/taxol combination in ovarian cancer. The present manuscript reports on the first international monothematic workshop on SLFN11. Several researchers from around the world, directly and actively involved in the discovery, functional characterization, and study of SLFN11 for its biomarker and medicinal properties gathered to share their views on the current knowledge advances concerning SLFN11. The aim of the manuscript is to summarize the authors' interventions and the main take-home messages resulting from the workshop.

DOI： 10.1186/s12967-017-1296-3

PubMed

researchmap

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語  

Approximately half of high-grade serous epithelial ovarian cancers incur alterations in genes of homologous recombination (BRCA1, BRCA2, RAD51C, Fanconi anemia genes), and the rest incur alterations in other DNA repair pathways at high frequencies. Such cancer-specific gene alterations can confer selective sensitivity to DNA damaging agents such as cisplatin and carboplatin, topotecan, etoposide, doxorubicin, and gemcitabine. Originally presumed to inhibit DNA repair, PARP inhibitors that have recently been approved by the FDA for the treatment of advanced ovarian cancer also act as DNA damaging agents by inducing PARP-DNA complexes. These DNA damaging agents induce different types of DNA lesions that require various DNA repair genes for the repair, but commonly induce replication fork slowing or stalling, also referred to as replication stress. Replication stress activates DNA repair checkpoint proteins (ATR, CHK1), which prevent further DNA damage. Hence, targeting DNA repair genes or DNA repair checkpoint genes augments the anti-tumor activity of DNA damaging agents. This review describes the rational basis for using DNA repair and DNA repair checkpoint inhibitors as single agents. The review also presents the strategies combining these inhibitors with DNA damaging agents for ovarian cancer therapy based on specific gene alterations.

DOI： 10.1007/s10147-017-1145-7

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

Cisplatin and its platinum analogs, carboplatin and oxaliplatin, are some of the most widely used cancer chemotherapeutics. Although cisplatin and carboplatin are used primarily in germ cell, breast and lung malignancies, oxaliplatin is instead used almost exclusively to treat colorectal and other gastrointestinal cancers. Here we utilize a unique, multi-platform genetic approach to study the mechanism of action of these clinically established platinum anti-cancer agents, as well as more recently developed cisplatin analogs. We show that oxaliplatin, unlike cisplatin and carboplatin, does not kill cells through the DNA-damage response. Rather, oxaliplatin kills cells by inducing ribosome biogenesis stress. This difference in drug mechanism explains the distinct clinical implementation of oxaliplatin relative to cisplatin, and it might enable mechanistically informed selection of distinct platinum drugs for distinct malignancies. These data highlight the functional diversity of core components of front-line cancer therapy and the potential benefits of applying a mechanism-based rationale to the use of our current arsenal of anti-cancer drugs.

DOI： 10.1038/nm.4291

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

ALC1/CHD1L is a member of the SNF2 superfamily of ATPases carrying a macrodomain that binds poly(ADP-ribose). Poly(ADP-ribose) polymerase (PARP) 1 and 2 synthesize poly(ADP-ribose) at DNA-strand cleavage sites, promoting base excision repair (BER). Although depletion of ALC1 causes increased sensitivity to various DNA-damaging agents (H2O2, UV, and phleomycin), the role played by ALC1 in BER has not yet been established. To explore this role, as well as the role of ALC1's ATPase activity in BER, we disrupted the ALC1 gene and inserted the ATPase-dead (E165Q) mutation into the ALC1 gene in chicken DT40 cells, which do not express PARP2. The resulting ALC1-/- and ALC1-/E165Q cells displayed an indistinguishable hypersensitivity to methylmethane sulfonate (MMS), an alkylating agent, and to H2O2, indicating that ATPase plays an essential role in the DNA-damage response. PARP1-/- and ALC1-/-/PARP1-/- cells exhibited a very similar sensitivity to MMS, suggesting that ALC1 and PARP1 collaborate in BER. Following pulse-exposure to H2O2, PARP1-/- and ALC1-/-/PARP1-/- cells showed similarly delayed kinetics in the repair of single-strand breaks, which arise as BER intermediates. To ascertain ALC1's role in BER in mammalian cells, we disrupted the ALC1 gene in human TK6 cells. Following exposure to MMS and to H2O2, the ALC1-/- TK6 cell line showed a delay in single-strand-break repair. We therefore conclude that ALC1 plays a role in BER. Following exposure to H2O2, ALC1-/- cells showed compromised chromatin relaxation. We thus propose that ALC1 is a unique BER factor that functions in a chromatin context, most likely as a chromatin-remodeling enzyme.

DOI： 10.1371/journal.pone.0188320

PubMed

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Poly(ADP-ribose) polymerase inhibitors (PARPIs) kill cancer cells by trapping PARP1 and PARP2. Talazoparib, the most potent PARPI inhibitor (PARPI), exhibits remarkable selectivity among the NCI-60 cancer cell lines beyond BRCA inactivation. Our genomic analyses reveal high correlation between response to talazoparib and Schlafen 11 (SLFN11) expression. Causality was established in four isogenic SLFN11-positive and -negative cell lines and extended to olaparib. Response to the talazoparib-temozolomide combination was also driven by SLFN11 and validated in 36 small cell lung cancer cell lines, and in xenograft models. Resistance in SLFN11-deficient cells was caused neither by impaired drug penetration nor by activation of homologous recombination. Rather, SLFN11 induced irreversible and lethal replication inhibition, which was independent of ATR-mediated S-phase checkpoint. The resistance to PARPIs by SLFN11 inactivation was overcome by ATR inhibition, mechanistically because SLFN11-deficient cells solely rely on ATR activation for their survival under PARPI treatment. Our study reveals that SLFN11 inactivation, which is common (~45%) in cancer cells, is a novel and dominant resistance determinant to PARPIs.

DOI： 10.18632/oncotarget.12266

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press  

The intolerance of DNA polymerase δ (Polδ) to incorrect base pairing contributes to its extremely high accuracy during replication, but is believed to inhibit translesion synthesis (TLS). However, chicken DT40 cells lacking the POLD3 subunit of Polδ are deficient in TLS. Previous genetic and biochemical analysis showed that POLD3 may promote lesion bypass by Polδ itself independently of the translesion polymerase Polζ of which POLD3 is also a subunit. To test this hypothesis, we have inactivated Polδ proofreading in pold3 cells. This significantly restored TLS in pold3 mutants, enhancing dA incorporation opposite abasic sites. Purified proofreading-deficient human Polδ holoenzyme performs TLS of abasic sites in vitro much more efficiently than the wild type enzyme, with over 90% of TLS events resulting in dA incorporation. Furthermore, proofreading deficiency enhances the capability of Polδ to continue DNA synthesis over UV lesions both in vivo and in vitro. These data support Polδ contributing to TLS in vivo and suggest that the mutagenesis resulting from loss of Polδ proofreading activity may in part be explained by enhanced lesion bypass.

DOI： 10.1093/nar/gkw439

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

PURPOSE: SLFN11 was identified as a critical determinant of response to DNA-targeted therapies by analyzing gene expression and drug sensitivity of NCI-60 and CCLE datasets. However, how SLFN11 is regulated in cancer cells remained unknown. Ewing sarcoma, which is characterized by the chimeric transcription factor EWS-FLI1, has notably high SLFN11 expression, leading us to investigate whether EWS-FLI1 drives SLFN11 expression and the role of SLFN11 in the drug response of Ewing sarcoma cells. EXPERIMENTAL DESIGN: Binding sites of EWS-FLI1 on the SLFN11 promoter were analyzed by chromatin immunoprecipitation sequencing and promoter-luciferase reporter analyses. The relationship between SLFN11 and EWS-FLI1 were further examined in EWS-FLI1-knockdown or -overexpressing cells and in clinical tumor samples. RESULTS: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells. EWS-FLI1-mediated SLFN11 expression is responsible for high sensitivity of Ewing sarcoma to camptothecin and combinations of PARP inhibitors with temozolomide. Importantly, Ewing sarcoma patients with higher SLFN11 expression showed better tumor-free survival rate. The correlated expression between SLFN11 and FLI1 extends to leukemia, pediatric, colon, breast, and prostate cancers. In addition, expression of other ETS members correlates with SLFN11 in NCI-60 and CCLE datasets, and molecular experiments demonstrate that ETS1 acts as a positive regulator for SLFN11 expression in breast cancer cells. CONCLUSIONS: Our results imply the emerging relevance of SLFN11 as an ETS transcription factor response gene and for therapeutic response to topoisomerase I inhibitors and temozolomide-PARP inhibitor combinations in ETS-activated cancers.

DOI： 10.1158/1078-0432.CCR-14-2112

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/nar/gkv023

PubMed

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：Cancer Drug Discovery and Development  

DOI： 10.1007/978-3-319-14151-0_10

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

RING finger protein 4 (RNF4) represents a subclass of ubiquitin ligases that target proteins modified by the small ubiquitin-like modifier (SUMO) for ubiquitin-mediated degradation. We disrupted the RNF4 gene in chicken DT40 cells and found that the resulting RNF4(-/-) cells gradually lost proliferation capability. Strikingly, this compromised proliferation was associated with an unprecedented cellular effect: the gradual decrease in the number of intact chromosomes. In the 6 weeks after gene targeting, there was a 25% reduction in the DNA content of the RNF4(-/-) cells. Regarding trisomic chromosome 2, 60% of the RNF4(-/-) cells lost one homologue, suggesting that DNA loss was mediated by whole chromosome loss. To determine the cause of this chromosome loss, we examined cell-cycle checkpoint pathways. RNF4(-/-) cells showed a partial defect in the spindle assembly checkpoint, premature dissociation of sister chromatids, and a marked increase in the number of lagging chromosomes at anaphase. Thus, combined defects in SAC and sister chromatid cohesion may result in increased lagging chromosomes, leading to chromosome loss without accompanying chromosome gain in RNF4(-/-) cells. We therefore propose that RNF4 plays a novel role in preventing the loss of intact chromosomes and ensures the maintenance of chromosome integrity.

DOI： 10.1111/gtc.12173

Web of Science

researchmap

担当区分：筆頭著者   記述言語：英語  

Anti-cancer topoisomerase I (Top1) inhibitors (camptothecin and its derivatives irinotecan and topotecan, and indenoisoquinolines) induce lethal DNA lesions by stabilizing Top1-DNA cleavage complex (Top1cc). These lesions are repaired by parallel repair pathways including the tyrosyl-DNA phosphodiesterase 1 (TDP1)-related pathway and homologous recombination. As TDP1-deficient cells in vertebrates are hypersensitive to Top1 inhibitors, small molecules inhibiting TDP1 should augment the cytotoxicity of Top1 inhibitors. We developed a cell-based high-throughput screening assay for the discovery of inhibitors for human TDP1 using a TDP1-deficient chicken DT40 cell line (TDP1-/-) complemented with human TDP1 (hTDP1). Any compounds showing a synergistic effect with the Top1 inhibitor camptothecin (CPT) in hTDP1 cells should either be a TDP1-related pathway inhibitor or an inhibitor of alternate repair pathways for Top1cc. We screened the 400,000-compound Small Molecule Library Repository (SMLR, NIH Molecular Libraries) against hTDP1 cells in the absence or presence of CPT. After confirmation in a secondary screen using both hTDP1 and TDP1-/- cells in the absence or presence of CPT, five compounds were confirmed as potential TDP1 pathway inhibitors. All five compounds showed synergistic effect with CPT in hTDP1 cells, but not in TDP1-/- cells, indicating that the compounds inhibited a TDP1-related repair pathway. Yet, in vitro gel-based assay revealed that the five compounds did not inhibit TDP1 catalytic activity directly. We tested the compounds for their ability to inhibit poly(ADP-ribose)polymerase (PARP) because PARP inhibitors are known to potentiate the cytotoxicity of CPT by inhibiting the recruitment of TDP1 to Top1cc. Accordingly, we found that the five compounds inhibit catalytic activity of PARP by ELISA and Western blotting. We identified the most potent compound (Cpd1) that offers characteristic close to veliparib, a leading clinical PARP inhibitor. Cpd1 may represent a new scaffold for the development of PARP inhibitors.

DOI： 10.1016/j.dnarep.2014.03.006

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

Drug screening against novel targets is warranted to generate biochemical probes and new therapeutic drug leads. TDP1 and TDP2 are two DNA repair enzymes that have yet to be successfully targeted. TDP1 repairs topoisomerase I-, alkylation-, and chain terminator-induced DNA damage, whereas TDP2 repairs topoisomerase II-induced DNA damage. Here, we report the quantitative high-throughput screening (qHTS) of the NIH Molecular Libraries Small Molecule Repository using recombinant human TDP1. We also developed a secondary screening method using a multiple loading gel-based assay where recombinant TDP1 is replaced by whole cell extract (WCE) from genetically engineered DT40 cells. While developing this assay, we determined the importance of buffer conditions for testing TDP1, and most notably the possible interference of phosphate-based buffers. The high specificity of endogenous TDP1 in WCE allowed the evaluation of a large number of hits with up to 600 samples analyzed per gel via multiple loadings. The increased stringency of the WCE assay eliminated a large fraction of the initial hits collected from the qHTS. Finally, inclusion of a TDP2 counter-screening assay allowed the identification of two novel series of selective TDP1 inhibitors. (C) 2014 AACR.

DOI： 10.1158/1535-7163.MCT-13-0952

Web of Science

researchmap

記述言語：英語  

Novel substituted 2,3-dihydrobenzofuran-7-carboxamide (DHBF-7-carboxamide) and 2,3-dihydrobenzofuran-3(2H)-one-7-carboxamide (DHBF-3-one-7-carboxamide) derivatives were synthesized and evaluated as inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1). A structure-based design strategy resulted in lead compound 3 (DHBF-7-carboxamide; IC50 = 9.45 μM). To facilitate synthetically feasible derivatives, an alternative core was designed, DHBF-3-one-7-carboxamide (36, IC50 = 16.2 μM). The electrophilic 2-position of this scaffold was accessible for extended modifications. Substituted benzylidene derivatives at the 2-position were found to be the most potent, with 3',4'-dihydroxybenzylidene 58 (IC50 = 0.531 μM) showing a 30-fold improvement in potency. Various heterocycles attached at the 4'-hydroxyl/4'-amino of the benzylidene moiety resulted in significant improvement in inhibition of PARP-1 activity (e.g., compounds 66-68, 70, 72, and 73; IC50 values from 0.718 to 0.079 μM). Compound 66 showed selective cytotoxicity in BRCA2-deficient DT40 cells. Crystal structures of three inhibitors (compounds (-)-13c, 59, and 65) bound to a multidomain PARP-1 structure were obtained, providing insights into further development of these inhibitors.

DOI： 10.1021/jm5002502

PubMed

researchmap

記述言語：英語  

TDP1 and TDP2 were discovered and named based on the fact they process 3'- and 5'-DNA ends by excising irreversible protein tyrosyl-DNA complexes involving topoisomerases I and II, respectively. Yet, both enzymes have an extended spectrum of activities. TDP1 not only excises trapped topoisomerases I (Top1 in the nucleus and Top1mt in mitochondria), but also repairs oxidative damage-induced 3'-phosphoglycolates and alkylation damage-induced DNA breaks, and excises chain terminating anticancer and antiviral nucleosides in the nucleus and mitochondria. The repair function of TDP2 is devoted to the excision of topoisomerase II- and potentially topoisomerases III-DNA adducts. TDP2 is also essential for the life cycle of picornaviruses (important human and bovine pathogens) as it unlinks VPg proteins from the 5'-end of the viral RNA genome. Moreover, TDP2 has been involved in signal transduction (under the former names of TTRAP or EAPII). The DNA repair partners of TDP1 include PARP1, XRCC1, ligase III and PNKP from the base excision repair (BER) pathway. By contrast, TDP2 repair functions are coordinated with Ku and ligase IV in the non-homologous end joining pathway (NHEJ). This article summarizes and compares the biochemistry, functions, and post-translational regulation of TDP1 and TDP2, as well as the relevance of TDP1 and TDP2 as determinants of response to anticancer agents. We discuss the rationale for developing TDP inhibitors for combinations with topoisomerase inhibitors (topotecan, irinotecan, doxorubicin, etoposide, mitoxantrone) and DNA damaging agents (temozolomide, bleomycin, cytarabine, and ionizing radiation), and as novel antiviral agents.

DOI： 10.1016/j.dnarep.2014.03.020

PubMed

researchmap

担当区分：筆頭著者   記述言語：英語  

We recently showed that poly(ADP-ribose) polymerase (PARP) inhibitors exert their cytotoxicity primarily by trapping PARP-DNA complexes in addition to their NAD(+)-competitive catalytic inhibitory mechanism. PARP trapping is drug-specific, with olaparib exhibiting a greater ability than veliparib, whereas both compounds are potent catalytic PARP inhibitors. Here, we evaluated the combination of olaparib or veliparib with therapeutically relevant DNA-targeted drugs, including the topoisomerase I inhibitor camptothecin, the alkylating agent temozolomide, the cross-linking agent cisplatin, and the topoisomerase II inhibitor etoposide at the cellular and molecular levels. We determined PARP-DNA trapping and catalytic PARP inhibition in genetically modified chicken lymphoma DT40, human prostate DU145, and glioblastoma SF295 cancer cells. For camptothecin, both PARP inhibitors showed highly synergistic effects due to catalytic PARP inhibition, indicating the value of combining either veliparib or olaparib with topoisomerase I inhibitors. On the other hand, for temozolomide, PARP trapping was critical in addition to catalytic inhibition, consistent with the fact that olaparib was more effective than veliparib in combination with temozolomide. For cisplatin and etoposide, olaparib only showed no or a weak combination effect, which is consistent with the lack of involvement of PARP in the repair of cisplatin- and etoposide-induced lesions. Hence, we conclude that catalytic PARP inhibitors are highly effective in combination with camptothecins, whereas PARP inhibitors capable of PARP trapping are more effective with temozolomide. Our study provides insights in combination treatment rationales for different PARP inhibitors.

DOI： 10.1124/jpet.113.210146

PubMed

researchmap

記述言語：英語  

Poly(ADP-ribose) polymerases (PARP) attach poly(ADP-ribose) (PAR) chains to various proteins including themselves and chromatin. Topoisomerase I (Top1) regulates DNA supercoiling and is the target of camptothecin and indenoisoquinoline anticancer drugs, as it forms Top1 cleavage complexes (Top1cc) that are trapped by the drugs. Endogenous and carcinogenic DNA lesions can also trap Top1cc. Tyrosyl-DNA phosphodiesterase 1 (TDP1), a key repair enzyme for trapped Top1cc, hydrolyzes the phosphodiester bond between the DNA 3'-end and the Top1 tyrosyl moiety. Alternative repair pathways for Top1cc involve endonuclease cleavage. However, it is unknown what determines the choice between TDP1 and the endonuclease repair pathways. Here we show that PARP1 plays a critical role in this process. By generating TDP1 and PARP1 double-knockout lymphoma chicken DT40 cells, we demonstrate that TDP1 and PARP1 are epistatic for the repair of Top1cc. The N-terminal domain of TDP1 directly binds the C-terminal domain of PARP1, and TDP1 is PARylated by PARP1. PARylation stabilizes TDP1 together with SUMOylation of TDP1. TDP1 PARylation enhances its recruitment to DNA damage sites without interfering with TDP1 catalytic activity. TDP1-PARP1 complexes, in turn recruit X-ray repair cross-complementing protein 1 (XRCC1). This work identifies PARP1 as a key component driving the repair of trapped Top1cc by TDP1.

DOI： 10.1093/nar/gku088

PubMed

researchmap

担当区分：筆頭著者   記述言語：英語  

DOI： 10.1158/1535-7163.MCT-13-0803

PubMed

researchmap

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

Clinical topoisomerase I (Top1) and II (Top2) inhibitors trap topoisomerases on DNA, thereby inducing protein-linked DNA breaks. Cancer cells resist the drugs by removing topoisomerase-DNA complexes, and repairing the drug-induced DNA double-strand breaks (DSB) by homologous recombination and nonhomologous end joining (NHEJ). Because numerous enzymes and cofactors are involved in the removal of the topoisomerase-DNA complexes and DSB repair, it has been challenging to comprehensively analyze the relative contribution of multiple genetic pathways in vertebrate cells. Comprehending the relative contribution of individual repair factors would give insights into the lesions induced by the inhibitors and genetic determinants of response. Ultimately, this information would be useful to target specific pathways to augment the therapeutic activity of topoisomerase inhibitors. To this end, we put together 48 isogenic DT40 mutant cells deficient in DNA repair and generated one cell line deficient in autophagy (ATG5). Sensitivity profiles were established for three clinically relevant Top1 inhibitors (camptothecin and the indenoisoquinolines LMP400 and LMP776) and three Top2 inhibitors (etoposide, doxorubicin, and ICRF-193). Highly significant correlations were found among Top1 inhibitors as well as Top2 inhibitors, whereas the profiles of Top1 inhibitors were different from those of Top2 inhibitors. Most distinct repair pathways between Top1 and Top2 inhibitors include NHEJ, TDP1, TDP2, PARP1, and Fanconi Anemia genes, whereas homologous recombination seems relevant especially for Top1 and, to a lesser extent, for Top2 inhibitors. We also found and discuss differential pathways among Top1 inhibitors and Top2 inhibitors. (C)2013 AACR.

DOI： 10.1158/1535-7163.MCT-13-0551

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

Chain-terminating nucleoside analogs (CTNAs) that cause stalling or premature termination of DNA replication forks are widely used as anticancer and antiviral drugs. However, it is not well understood how cells repair the DNA damage induced by these drugs. Here, we reveal the importance of tyrosyl-DNA phosphodiesterase 1 (TDP1) in the repair of nuclear and mitochondrial DNA damage induced by CTNAs. On investigating the effects of four CTNAs-acyclovir (ACV), cytarabine (Ara-C), zidovudine (AZT) and zalcitabine (ddC)-we show that TDP1 is capable of removing the covalently linked corresponding CTNAs from DNA 3'-ends. We also show that Tdp1(-/-) cells are hypersensitive and accumulate more DNA damage when treated with ACV and Ara-C, implicating TDP1 in repairing CTNA-induced DNA damage. As AZT and ddC are known to cause mitochondrial dysfunction, we examined whether TDP1 repairs the mitochondrial DNA damage they induced. We find that AZT and ddC treatment leads to greater depletion of mitochondrial DNA in Tdp1(-/-) cells. Thus, TDP1 seems to be critical for repairing nuclear and mitochondrial DNA damage caused by CTNAs.

DOI： 10.1093/nar/gkt483

Web of Science

PubMed

J-GLOBAL

researchmap

担当区分：筆頭著者   記述言語：英語  

DOI： 10.1158/0008-5472.CAN-12-2753

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

The abortive activity of topoisomerases can result in clastogenic and/or lethal DNA damage in which the topoisomerase is covalently linked to the 3'- or 5'-terminus of a DNA strand break. This type of DNA damage is implicated in chromosome translocations and neurological disease and underlies the clinical efficacy of an important class of anticancer topoisomerase 'poisons'. Tyrosyl DNA phosphodiesterase-1 protects cells from abortive topoisomerase I (Top1) activity by hydrolyzing the 3'-phosphotyrosyl bond that links Top1 to a DNA strand break and is currently the only known human enzyme that displays this activity in cells. Recently, we identified a second tyrosyl DNA phosphodiesterase (TDP2; aka TTRAP/EAPII) that possesses weak 3'-tyrosyl DNA phosphodiesterase (3'-TDP) activity, in vitro. Herein, we have examined whether TDP2 contributes to the repair of Top1-mediated DNA breaks by deleting Tdp1 and Tdp2 separately and together in murine and avian cells. We show that while deletion of Tdp1 in wild-type DT40 cells and mouse embryonic fibroblasts decreases DNA strand break repair rates and cellular survival in response to Top1-induced DNA damage, deletion of Tdp2 does not. However, deletion of both Tdp1 and Tdp2 reduces rates of DNA strand break repair and cell survival below that observed in Tdp1(-/-) cells, suggesting that Tdp2 contributes to cellular 3'-TDP activity in the absence of Tdp1. Consistent with this idea, over-expression of human TDP2 in Tdp1(-/-)/Tdp2(-/-/-) DT40 cells increases DNA strand break repair rates and cell survival above that observed in Tdp1(-/-) DT40 cells, suggesting that Tdp2 over-expression can partially complement the defect imposed by loss of Tdp1. Finally, mice lacking both Tdp1 and Tdp2 exhibit greater sensitivity to Top1 poisons than do mice lacking Tdp1 alone, further suggesting that Tdp2 contributes to the repair of Top1-mediated DNA damage in the absence of Tdp1. In contrast, we failed to detect a contribution for Tdp1 to repair Top2-mediated damage. Together, our data suggest that Tdp1 and Tdp2 fulfil overlapping roles following Top1-induced DNA damage, but not following Top2-induced DNA damage, in vivo.

DOI： 10.1093/nar/gks622

Web of Science

J-GLOBAL

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) repairs topoisomerase I cleavage complexes (Top1cc) by hydrolyzing their 3'-phosphotyrosyl DNA bonds and repairs bleomycin-induced DNA damage by hydrolyzing 3'-phosphoglycolates. Yeast Tdp1 has also been implicated in the repair of topoisomerase II-DNA cleavage complexes (Top2cc). To determine whether vertebrate Tdp1 is involved in the repair of various DNA end-blocking lesions, we generated Tdp1 knock-out cells in chicken DT40 cells (Tdp1(-/-)) and Tdp1-complemented DT40 cells with human TDP1. We found that Tdp1(-/-) cells were not only hypersensitive to camptothecin and bleomycin but also to etoposide, methyl methanesulfonate (MMS), H2O2, and ionizing radiation. We also show they were deficient in mitochondrial Tdp1 activity. In biochemical assays, recombinant human TDP1 was found to process 5'-phosphotyrosyl DNA ends when they mimic the 5'-overhangs of Top2cc. Tdp1 also processes 3'-deoxyribose phosphates generated from hydrolysis of abasic sites, which is consistent with the hypersensitivity of Tdp1(-/-) cells to MMS and H2O2. Because recent studies established that CtIP together with BRCA1 also repairs topoisomerase-mediated DNA damage, we generated dual Tdp1-CtIP-deficient DT40 cells. Our results show that Tdp1 and CtIP act in parallel pathways for the repair of Top1cc and MMS-induced lesions but are epistatic for Top2cc. Together, our findings reveal a broad involvement of Tdp1 in DNA repair and clarify the role of human TDP1 in the repair of Top2-induced DNA damage.

DOI： 10.1074/jbc.M111.333963

Web of Science

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Bone undergoes remodeling consisting of osteoclastic bone resorption followed by osteoblastic bone formation throughout life. Although the effects of bone morphogenetic protein (BMP) signals on osteoblasts have been studied extensively, the function of BMP signals in osteoclasts has not been fully elucidated. To delineate the function of BMP signals in osteoclasts during bone remodeling, we deleted BMP receptor type IA (Bmpr1a) in an osteoclast-specific manner using a knock-in Cre mouse line to the cathepsin K locus (Ctsk(Cre/+); Bmpr1a(flox/flox), designated as Bmpr1a(Delta Oc/Delta Oc)). Cre was specifically expressed in multinucleated osteoclasts in vivo. Cre-dependent deletion of the Bmpr1a gene occurred at 4 days after cultivation of bone marrow macrophages obtained from Bmpr1a(Delta Oc/Delta Oc) with RANKL. These results suggested that Bmpr1a was deleted after formation of osteoclasts in Bmpr1a(Delta Oc/Delta Oc) mice. Expression of bone-resorption markers increased, thus suggesting that BMPRIA signaling negatively regulates osteoclast differentiation. Trabeculae in tibia and femurs were thickened in 3.5-, 8-, and 12-week-old Bmpr1a(Delta Oc/Delta Oc) mice. Bone histomorphometry revealed increased bone volume associated with increased osteoblastic bone-formation rates (BFR) in the remodeling bone of the secondary spongiosa in Bmpr1a(Delta Oc/Delta Oc) tibias at 8 weeks of age. For comparison, we also induced an osteoblast-specific deletion of Bmpr1a using Col1a1-Cre. The resulting mice showed increased bone volume with marked decreases in BFR in tibias at 8 weeks of age. These results indicate that deletion of Bmpr1a in differentiated osteoclasts increases osteoblastic bone formation, thus suggesting that BMPR1A signaling in osteoclasts regulates coupling to osteoblasts by reducing bone-formation activity during bone remodeling. (C) 2011 American Society for Bone and Mineral Research.

DOI： 10.1002/jbmr.477

Web of Science

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT  

The USP1/UAF1 complex deubiquitinates the Fanconi anemia protein FANCD2, thereby promoting homologous recombination and DNA cross-link repair. How USP1/UAF1 is targeted to the FANCD2/FANCI heterodimer has remained unknown. Here we show that UAF1 contains a tandem repeat of SUMO-like domains in its C terminus (SLD1 and SLD2). SLD2 binds directly to a SUMO-like domain-interacting motif (SIM) on FANCI. Deletion of the SLD2 sequence of UAF1 or mutation of the SIM on FANCI disrupts UAF1/FANCI binding and inhibits FANCD2 deubiquitination and DNA repair. The USP1/UAF1 complex also deubiquitinates PCNA-Ub, and deubiquitination requires the PCNA-binding protein hELG1. The SLD2 sequence of UAF1 binds to a SIM on hELG1, thus targeting the USP1/UAF1 complex to its PCNA-Ub substrate. We propose that the regulated targeting of USP1/UAF1 to its DNA repair substrates, FANCD2-Ub and PCNA-Ub, by SLD-SIM interactions coordinates homologous recombination and translesion DNA synthesis.

DOI： 10.1101/gad.17020911

Web of Science

researchmap

記述言語：英語   出版者・発行元：AMER ASSOC CANCER RESEARCH  

DOI： 10.1158/1538-7445.FBCR11-PR4

Web of Science

J-GLOBAL

researchmap

記述言語：英語  

DOI： 10.1128/MCB.05058-11

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Bone morphogenetic proteins (BMPs) play critical roles at various stages in endochondral bone formation. In vitro studies have demonstrated that Smad7 regulates transforming growth factor-beta and BMP signals by inhibiting Smad pathways in chondrocytes. However, the in vivo roles of Smad7 during cartilage development are unknown. To investigate distinct effects of Smad7 at different stages during chondrocyte differentiation, we generated a series of conditional transgenic mice that overexpress Smad7 in chondrocytes at various steps of differentiation by using the Cre/loxP system. Wegenerated Col11a2-lacZ(floxed)-Smad7 transgenic mice and mated them with three types of Cre transgenic mice to obtain Smad7(Prx1), Smad7(11Enh), and Smad7(11Prom) conditional transgenic mice. Smad7(Prx1) mice overexpressing Smad7 in condensing mesenchymal cells showed disturbed mesenchymal condensation associated with decreased Sox9 expression, leading to poor cartilage formation. Smad7(11Enh) mice overexpressing Smad7 in round chondrocytes showed decreased chondrocyte proliferation rates. Smad7(11Prom) mice overexpressing Smad7 in flat chondrocytes showed inhibited maturation of chondrocytes toward hypertrophy. Micromass culture of mesenchymal cells showed that BMP-induced cartilaginous nodule formation was down-regulated by overexpression of Smad7, but not Smad6. Overexpression of Smad7, but not Smad6, down-regulated the phosphorylation of p38 MAPKs. Our data provide in vivo evidence for distinct effects of Smad7 at different stages during chondrocyte differentiation and suggest that Smad7 in prechondrogenic cells inhibits chondrocyte differentiation possibly by down- regulating BMP- activated p38 MAPK pathways.

DOI： 10.1074/jbc.M801175200

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

The retinoid X receptor beta gene (Rxrb) is located just upstream of the alpha 2(XI) collagen chain gene (Col11a2) in a head-to-tail manner. However, the domain structures of these genes are unknown. Col11a2 is specifically expressed in cartilage. In the present study, we found Rxrb expression in various tissues with low expression in the cartilage. Col11a2 1st intron enhancer directed cartilage specific expression when linked to the heterologous promoter in transgenic mice. These results suggest the presence of enhancer-blocking elements that insulate Rxrb promoter from the Col11a2 enhancer. So far, most of insulators examined in vertebrates contain a binding site for CTCF. We found two possible CTCF-binding sites: one (11P) in the intergenic region between Rxrb and Col11a2 by electrophoretic mobility shift assays, and the other in the 4th intron of RXRB by data base search. To examine the function of these elements, we prepared bacterial artificial chromosome (BAC) transgene constructs containing a 142-kb genomicDNAinsert with RXRB and COL11A2 sequences in the middle. Mutation of 11P significantly decreased the RXRB promoter activity in muscular cells and significantly increased expression levels of RXRB in chondrosarcoma cells. In transgenic mouse assays, the wild-type BAC transgene partly recapitulated endogenous Rxrb expression patterns. A 507-bp deletion mutation including 11P enhanced the cartilage-specific activity of the RXRB promoter in BACtransgenic mice. Chromatin immunoprecipitation analysis showed that CTCF was associated with RX4, but not with 11P. Our results showed that the intergenic sequence including 11P insulates Rxrb promoter from Col11a2 enhancer, possibly associating with unknown factors that recognize a motif similar to CTCF.

DOI： 10.1074/jbc.M803657200

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER JAPAN KK  

Synthetic porous ceramic made of hydroxyapatite (HA) has been used as a bone graft substitute. In the present study we investigated whether low-intensity pulsed ultrasound (LIPUS) accelerates bone ingrowth into the pores of HA ceramic. Application of LIPUS did not mechanically weaken porous ceramic that was immersed in water in vitro. In vivo experiments using rabbits showed that LIPUS application for 2 weeks significantly increased osteoblast number and bone area in the central part of the porous HA ceramic implanted in the femoral condyle in comparison with similarly implanted HA ceramic that was not exposed to LIPUS. LIPUS application for 3 weeks significantly increased mineralized tissue volume and mineral content in the porous HA ceramic. Wound healing assays revealed increased migration of MC3T3-E1 cells as a result of LIPUS treatment, partly accounting for the increased osteoblast number. Use of porous HA ceramic combined with LIPUS may be a promising treatment for filling large bone defects in a clinical setting.

DOI： 10.1007/s00774-007-0777-5

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Introduction: Bone morphogenetic proteins (BMPs) act on various types of cells. Although involvement of BMP signals in osteoblast differentiation has been studied extensively, the effects of BMPs on osteoclasts have not been widely researched. Consequently, the net effects of BMPs on bone remain unclear. The purpose of this study was to delineate more fully the role of BMPs in skeletal biology.
Materials and Methods: We generated transgenic mice that express BMP4 or noggin in bone under the control of the 2.3-kb alpha 1(I) collagen chain gene (Col1a1) promoter, and analyzed their bone phenotype. We also analyzed bone of transgenic mice expressing BMP4 specifically in cartilage.
Results: Mice overexpressing BMP4 in bone developed severe osteopenia with increased osteoclast number. Mice overexpressing noggin, a BMP antagonist, in bone showed increased bone volume associated with decreased bone formation rate and decreased osteoclast number. The noggin-transgenic tibias exhibited reduced periosteal bone formation and reduced resorption of immature bone in marrow spaces, associated with frequent fractures at the diaphysis. Co-culture of primary osteoblasts prepared from noggin-transgenic calvariae and wildtype spleen cells resulted in poor osteoclast formation, which was rescued by addition of recombinant BMP2, suggesting that noggin inhibits osteoclast formation by attenuating BMP activities in noggin-transgenic mice. The expression levels of Rankl were not decreased in primary osteoblasts from noggin transgenic mice. Immunoblot analysis showed increased phosphorylation of Smad1/5/8 in osteoclast precursor cells after 20-minute treatment with BMPs, suggesting that these cells are stimulated by BMPs. Mice overexpressing BMP4 in cartilage had enlarged bones containing thick trabeculae, possibly because of expansion of cartilage anlagen.
Conclusions: Overexpression of noggin in bone revealed that BMP signals regulate bone development through stimulation of osteoblasts and osteoclasts.

DOI： 10.1359/JBMR.060411

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROCKEFELLER UNIV PRESS  

Biochemical experiments have shown that Smad6 and Smad ubiquitin regulatory factor 1 (Smurf1) block the signal transduction of bone morphogenetic proteins (BMPs). However, their in vivo functions are largely unknown. Here, we generated transgenic mice overexpressing Smad6 in chondrocytes. Smad6 transgenic mice showed postnatal dwarfism with osteopenia and inhibition of Smad1/5/8 phosphorylation in chondrocytes. Endochondral ossification during development in these mice was associated with almost normal chondrocyte proliferation, significantly delayed chondrocyte hypertrophy, and thin trabecular bone. The reduced population of hypertrophic chondrocytes after birth seemed to be related to impaired bone growth and formation. Organ culture of cartilage rudiments showed that chondrocyte hypertrophy induced by BMP2 was inhibited in cartilage prepared from Smad6 transgenic mice. We then generated transgenic mice overexpressing Smurf1 in chondrocytes. Abnormalities were undetectable in Smurf1 transgenic mice. Mating Smad6 and Smurf1 transgenic mice produced double-transgenic pups with more delayed endochondral ossification than Smad6 transgenic mice. These results provided evidence that Smurf1 supports Smad6 function in vivo.

DOI： 10.1083/jcb.200311015

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

DOI： 10.1158/1538-7445.AM2014-1718

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

DOI： 10.1158/1535-7163.TARG-13-CN05-01

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

DOI： 10.1158/1538-7445.AM2013-3421

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER ASSOC CANCER RESEARCH  

DOI： 10.1158/1538-7445.AM2012-4689

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：ELSEVIER SCIENCE INC  

DOI： 10.1016/j.bone.2006.01.136

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：AMER SOC BONE & MINERAL RES  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：ELSEVIER SCIENCE INC  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：ELSEVIER SCIENCE INC  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：ELSEVIER SCIENCE INC  

Web of Science

researchmap

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：ELSEVIER SCIENCE INC  

Web of Science

researchmap