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Lin X, Soni A, Hessenow R, Sun Y, Mladenov E, Guberina M, Stuschke M, Iliakis G. Talazoparib enhances resection at DSBs and renders HR-proficient cancer cells susceptible to Polθ inhibition. Radiother Oncol 2024; 200:110475. [PMID: 39147034 DOI: 10.1016/j.radonc.2024.110475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 07/02/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024]
Abstract
BACKGROUND AND PURPOSE The PARP inhibitor (PARPi), Talazoparib (BMN673), effectively and specifically radiosensitizes cancer cells. Radiosensitization is mediated by a shift in the repair of ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) toward PARP1-independent, alternative end-joining (alt-EJ). DNA polymerase theta (Polθ) is a key component of this PARP1-independent alt-EJ pathway and we show here that its inhibition can further radiosensitize talazoparib-treated cells. The purpose of the present work is to explore mechanisms and dynamics underpinning enhanced talazoparib radiosensitization by Polθ inhibitors in HR-proficient cancer cells. METHODS AND MATERIALS Radiosensitization to PARPis, talazoparib, olaparib, rucaparib and veliparib was assessed by clonogenic survival. Polθ-proficient and -deficient cells were treated with PARPis and/or with the Polθ inhibitors ART558 or novobiocin. The role of DNA end-resection was studied by down-regulating CtIP and MRE11 expression using siRNAs. DSB repair was assessed by scoring γH2AX foci. The formation of chromosomal abnormalities was assessed as evidence of alt-EJ function using G2-specific cytogenetic analysis. RESULTS Talazoparib exerted pronounced radiosensitization that varied among the tested cancer cell lines; however, radiosensitization was undetectable in normal cells. Other commonly used PARPis, olaparib, veliparib, or rucaparib were ineffective radiosensitizers under our experimental conditions. Although genetic ablation or pharmacological inhibition of Polθ only mildly radiosensitized cancer cells, talazoparib-treated cells were markedly further radiosensitized. Mechanistically, talazoparib shunted DSBs to Polθ-dependent alt-EJ by enhancing DNA end-resection in a CtIP- and MRE11-dependent manner - an effect detectable at low, but not high IR doses. Chromosomal translocation analysis in talazoparib-treated cells exposed to Polθ inhibitors suggested that PARP1- and Polθ-dependent alt-EJ pathways may complement, but also back up each other. CONCLUSION We propose that talazoparib promotes low-dose, CtIP/MRE11-dependent resection and increases the reliance of irradiated HR-proficient cancer cells, on Polθ-mediated alt-EJ. The combination of Polθ inhibitors with talazoparib suppresses this option and causes further radiosensitization. The results suggest that Polθ inhibition may be exploited to maximize talazoparib radiosensitization of HR-proficient tumors in the clinic.
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Affiliation(s)
- Xixi Lin
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany
| | - Aashish Soni
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany.
| | - Razan Hessenow
- West German Proton Therapy Center Essen (WPE), University of Duisburg-Essen, 45147, Essen, Germany
| | - Yanjie Sun
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; West German Proton Therapy Center Essen (WPE), University of Duisburg-Essen, 45147, Essen, Germany
| | - Emil Mladenov
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany
| | - Maja Guberina
- Department of Radiation Therapy, West German Cancer Center, University Hospital Essen, University Duisburg-Essen, 45147, Essen, Germany; German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147, Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Department of Radiation Therapy, West German Cancer Center, University Hospital Essen, University Duisburg-Essen, 45147, Essen, Germany; German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147, Essen, Germany
| | - George Iliakis
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany.
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Soni A, Lin X, Mladenov E, Mladenova V, Stuschke M, Iliakis G. BMN673 Is a PARP Inhibitor with Unique Radiosensitizing Properties: Mechanisms and Potential in Radiation Therapy. Cancers (Basel) 2022; 14:cancers14225619. [PMID: 36428712 PMCID: PMC9688666 DOI: 10.3390/cancers14225619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/10/2022] [Accepted: 11/13/2022] [Indexed: 11/17/2022] Open
Abstract
BMN673 is a relatively new PARP inhibitor (PARPi) that exhibits superior efficacy in vitro compared to olaparib and other clinically relevant PARPi. BMN673, similar to most clinical PARPi, inhibits the catalytic activities of PARP-1 and PARP-2 and shows impressive anticancer potential as monotherapy in several pre-clinical and clinical studies. Tumor resistance to PARPi poses a significant challenge in the clinic. Thus, combining PARPi with other treatment modalities, such as radiotherapy (RT), is being actively pursued to overcome such resistance. However, the modest to intermediate radiosensitization exerted by olaparib, rucaparib, and veliparib, limits the rationale and the scope of such combinations. The recently reported strong radiosensitizing potential of BMN673 forecasts a paradigm shift on this front. Evidence accumulates that BMN673 may radiosensitize via unique mechanisms causing profound shifts in the balance among DNA double-strand break (DSB) repair pathways. According to one of the emerging models, BMN673 strongly inhibits classical non-homologous end-joining (c-NHEJ) and increases reciprocally and profoundly DSB end-resection, enhancing error-prone DSB processing that robustly potentiates cell killing. In this review, we outline and summarize the work that helped to formulate this model of BMN673 action on DSB repair, analyze the causes of radiosensitization and discuss its potential as a radiosensitizer in the clinic. Finally, we highlight strategies for combining BMN673 with other inhibitors of DNA damage response for further improvements.
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Affiliation(s)
- Aashish Soni
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Xixi Lin
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Emil Mladenov
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Veronika Mladenova
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - George Iliakis
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Correspondence: ; Tel.: +49-201-723-4152
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Singh J, Hatcher S, Ku AA, Ding Z, Feng FY, Sharma RA, Pfister SX. Model Selection for the Preclinical Development of New Drug-Radiotherapy Combinations. Clin Oncol (R Coll Radiol) 2021; 33:694-704. [PMID: 34474951 DOI: 10.1016/j.clon.2021.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/13/2021] [Accepted: 08/11/2021] [Indexed: 12/12/2022]
Abstract
Radiotherapy plays an essential role in the treatment of more than half of all patients with cancer. In recent decades, advances in devices that deliver radiation and the development of treatment planning software have helped radiotherapy attain precise tumour targeting with minimal toxicity to surrounding tissues. Simultaneously, as more targeted drug therapies are being brought into the market, there has been significant interest in improving cure rates for cancer by adding drugs to radiotherapy to widen the therapeutic window, the difference between normal tissue toxicity and treatment efficacy. The development of new combination therapies will require judicious adaptation of preclinical models that are routinely used for traditional drug discovery. Here we highlight the strengths and weaknesses of each of these preclinical models and discuss how they can be used optimally to identify new and clinically beneficial drug-radiotherapy combinations.
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Affiliation(s)
- J Singh
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA
| | - S Hatcher
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA
| | - A A Ku
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA
| | - Z Ding
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA
| | - F Y Feng
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California, USA; Division of Hematology and Oncology, Department of Medicine, University of California, San Francisco, California, USA; Department of Radiation Oncology, University of California, San Francisco, California, USA; Department of Urology, University of California, San Francisco, California, USA
| | - R A Sharma
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA; UCL Cancer Institute, University College London, London, UK
| | - S X Pfister
- Global Translational Science, Varian, a Siemens Healthineers company, Palo Alto, California, USA.
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Li J, Xue H, Xiang Z, Song S, Yan R, Ji J, Zhu Z, Wei C, Yu Y. Genetic Profiles Affect the Biological Effects of Serine on Gastric Cancer Cells. Front Pharmacol 2020; 11:1183. [PMID: 32848786 PMCID: PMC7411129 DOI: 10.3389/fphar.2020.01183] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 12/18/2022] Open
Abstract
A high serine content in body fluid was identified in a portion of patients with gastric cancer, but its biological significance was not clear. Here, we investigated the biological effect of serine on gastric cancer cells. Serine was added into the culture medium of MGC803 and HGC27 cancer cells, and its influence on multiple biological functions, such as cell growth, migration and invasion, and drug resistance was analyzed. We examined the global transcriptomic profiles in these cultured cells with high serine content. Both MGC803 and HGC27 cell lines were originated from male patients, however, their basal gene expression patterns were very different. The finding of cell differentiation-associated genes, ALPI, KRT18, TM4SF1, KRT81, A2M, MT1E, MUC16, BASP1, TUSC3, and PRSS21 in MGC803 cells suggested that this cell line was more poorly differentiated, compared to HGC27 cell line. When the serine concentration was increased to 150mg/ml in medium, the response of these two gastric cancer cell lines was different, particularly on cell growth, cell migration, and invasion and 5-FU resistance. In animal experiment, administration of high concentration of serine promoted cancer cell metastasis to local lymph node. Taken together, we characterized the basal gene expressing profiles of MGC803 and HGC27. The HGC27 cells were more differentiated than MGC803 cells. MGC803 cells were more sensitive to the change of serine content. Our results suggested that the responsiveness of cancer cells to microenvironmental change is associated with their genetic background.
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Affiliation(s)
- Jun Li
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hongzhang Xue
- Department of Bioinformatics and Biostatistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhen Xiang
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuzheng Song
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ranlin Yan
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ji
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhenggang Zhu
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chaochun Wei
- Department of Bioinformatics and Biostatistics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,SJTU-Yale Joint Center for Biostatistics and Data Science, Shanghai Jiao Tong University, Shanghai, China
| | - Yingyan Yu
- Department of Surgery of Ruijin Hospital, Shanghai Institute of Digestive Surgery, and Shanghai Key Laboratory for Gastric Neoplasms, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Li Z, Tamari K, Seo Y, Minami K, Takahashi Y, Tatekawa S, Otani K, Suzuki O, Isohashi F, Ogawa K. Dihydroouabain, a novel radiosensitizer for cervical cancer identified by automated high-throughput screening. Radiother Oncol 2020; 148:21-29. [PMID: 32311597 DOI: 10.1016/j.radonc.2020.03.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/09/2022]
Abstract
BACKGROUND AND PURPOSE Radiotherapy plays a crucial role in the treatment of cervical cancer, but existing radiosensitizers have limited efficacy in clinical applications. The aims of this study were to establish and verify an efficient method for identifying new radiosensitizers, to use this to identify candidate radiosensitizers for cervical cancer, and to investigate the specific mechanisms of these when used in combination with radiotherapy. MATERIALS AND METHODS An automated platform for identifying radiosensitizers for cervical cancer was created based on high-throughput screening technology. The radiosensitizing effects of candidate compounds from the LOPAC1280 chemical library were evaluated in radiosensitive and radioresistant cervical cancer cells using a clonogenic survival assay, with cell cycle analyses, and western blot analyses performed for both cell lines. RESULTS The automated high-throughput screening approach identified four hit compounds. One of the most potent candidates was dihydroouabain (DHO), an inhibitor of Na+/K+-ATPase that has not previously been classified as a radiosensitizer. DHO significantly enhanced radiosensitivity in cervical cancer cells. It also abrogated radiation-induced S phase arrest in cervical cancer cells. Combination treatment significantly caused the inhibition of Chk1 and increased DNA double-strand breaks (DSB). CONCLUSIONS DHO is a novel radiosensitizer for the treatment of cervical cancer. The automated high-throughput screening platform developed in this study proved to be powerful and effective, with the potential to be widely used in the future identification of radiosensitizers.
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Affiliation(s)
- Zhihao Li
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keisuke Tamari
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan.
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kazumasa Minami
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yutaka Takahashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Shotaro Tatekawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keisuke Otani
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Osamu Suzuki
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Fumiaki Isohashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
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