1
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Sato H, Ito T, Hayashi T, Kitano S, Erdjument-Bromage H, Bott MJ, Toyooka S, Zauderer M, Ladanyi M. The BAP1 nuclear deubiquitinase is involved in the nonhomologous end-joining pathway of double-strand DNA repair through interaction with DNA-PK. Oncogene 2024; 43:1087-1097. [PMID: 38383726 DOI: 10.1038/s41388-024-02966-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 01/16/2024] [Accepted: 02/02/2024] [Indexed: 02/23/2024]
Abstract
BRCA1-associated protein 1 (BAP1) has emerged as a major tumor suppressor gene in diverse cancer types, notably in malignant pleural mesothelioma (DPM), and has also been identified as a germline cancer predisposition gene for DPM and other select cancers. However, its role in the response to DNA damage has remained unclear. Here, we show that BAP1 inactivation is associated with increased DNA damage both in Met-5A human mesothelial cells and human DPM cell lines. Through proteomic analyses, we identified PRKDC as an interaction partner of BAP1 protein complexes in DPM cells and 293 T human embryonic kidney cells. PRKDC encodes the catalytic subunit of DNA protein kinase (DNA-PKcs) which functions in the nonhomologous end-joining (NHEJ) pathway of DNA repair. Double-stranded DNA damage resulted in prominent nuclear expression of BAP1 in DPM cells and phosphorylation of BAP1 at serine 395. A plasmid-based NHEJ assay confirmed a significant effect of BAP1 knockdown on cellular NHEJ activity. Combination treatment with X-ray irradiation and gemcitabine (as a radiosensitizer) strongly suppressed the growth of BAP1-deficient cells. Our results suggest reciprocal positive interactions between BAP1 and DNA-PKcs, based on phosphorylation of BAP1 by the latter and deubiquitination of DNA-PKcs by BAP1. Thus, functional interaction of BAP1 with DNA-PKcs supports a role for BAP1 in NHEJ DNA repair and may provide the basis for new therapeutic strategies and new insights into its role as a tumor suppressor.
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Affiliation(s)
- Hiroki Sato
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Tatsuo Ito
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Hygiene, Kawasaki Medical University, Okayama, Japan
| | - Takuo Hayashi
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Shigehisa Kitano
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hediye Erdjument-Bromage
- Kimmel Center for Biology and Medicine at Skirball Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
| | - Matthew J Bott
- Thoracic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Shinichi Toyooka
- Department of Thoracic, Breast and Endocrinological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Marjorie Zauderer
- Thoracic Oncology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Marc Ladanyi
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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2
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Mori H, Tanoue S, Takaji R, Ueda S, Okahara M, Ueda SS. Arterial Administration of DNA Crosslinking Agents with Restraint of Homologous Recombination Repair by Intravenous Low-Dose Gemcitabine Is Effective for Locally Advanced Pancreatic Cancer. Cancers (Basel) 2022; 14:cancers14010220. [PMID: 35008384 PMCID: PMC8750330 DOI: 10.3390/cancers14010220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Pancreatic cancer is considered incurable, and most cases are detected in the advanced stages. Establishing a new, effective interventional treatment for advanced pancreatic cancer is a pressing issue. Pretreatment with gemcitabine had a restraining effect on the homologous DNA recombination repair (HRR) of DNA crosslinking, inhibiting the function of Rad51, of which expression is found to be increased in pancreatic cancer. The aim of our prospective study was to assess the potential value of the arterial administration of DNA crosslinking agents after intravenous administration of low-dose gemcitabine for patients with advanced pancreatic cancer. We confirmed, among forty-five patients with unresectable advanced pancreatic cancer, that a patient subgroup of locally advanced pancreatic cancer (LAPC, 10 patients) who underwent these treatment courses successively more than twice in the first 6 months had 33 months of overall survival, 31 months of local progression free survival, and a complete response of 40%. This treatment can be a new treatment option for LAPC. Abstract (1) Background: Pretreatment by Rad51-inhibitory substances such as gemcitabine followed by arterial chemotherapy using antineoplastic agents causing DNA crosslink might be more beneficial for patients with locally advanced pancreatic cancers than conventional treatments. The efficacy of arterial administration of DNA crosslinking agents with pretreatment of intravenous low-dose gemcitabine for patients with unresectable locally advanced or metastatic pancreatic cancer (LAPC or MPC) is evaluated. (2) Methods: A single-arm, single-center, institutional review board-approved prospective study was conducted between 2005 and 2015. Forty-five patients (23 LAPC, 22 MPC) were included. Patients received a weekly low dose of gemcitabine intravenously for three weeks followed by arterial administration of mitomycin C and epirubicin hydrochloride at tumor-supplying arteries on the fifth or sixth week. This treatment course was repeated at 1.5-to-2-month intervals. Overall survival (OS), local progression-free survival (LPFS), and therapeutic response were evaluated. LAPC or MPC were divided according to treatment compliance, excellent or poor (1 or 2), to subgroups L1, L2, M1, and M2. (3) Results: OS of LAPC and MPC were 23 months and 13 months, respectively. The OS of LAPC with excellent treatment compliance (subgroup L1, 10 patients) was 33 months with 31 months of LPFS, and four patients (40%) had a complete response (CR). The OS of the L1 subgroup was significantly longer than those of other subgroups L2, M1, and M2, which were 17 months, 17 months, and 8 months, respectively. As Grade 3 adverse effects, severe bone marrow suppression, interstitial pneumonitis, and hemolytic uremic syndrome were observed in six (13.0%), three (6.5%), and three (6.5%) patients, respectively. (4) Conclusions: Arterial DNA crosslinking with the systemic restraint of homologous recombination repair can be a new treatment option for LAPC.
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Affiliation(s)
- Hiromu Mori
- Department of Radiology, Nagato Memorial Hospital, Saiki 876-0835, Japan;
- Department of Radiology, Faculty of Medicine, Oita University, Yufu 879-5593, Japan; (S.T.); (R.T.); (M.O.)
- Correspondence: ; Tel.: +81-80-4270-0753
| | - Shuichi Tanoue
- Department of Radiology, Faculty of Medicine, Oita University, Yufu 879-5593, Japan; (S.T.); (R.T.); (M.O.)
- Department of Radiology, School of Medicine, Kurume University, Kurume 830-0011, Japan
| | - Ryo Takaji
- Department of Radiology, Faculty of Medicine, Oita University, Yufu 879-5593, Japan; (S.T.); (R.T.); (M.O.)
| | - Shinya Ueda
- Department of Radiology, Nagato Memorial Hospital, Saiki 876-0835, Japan;
- San-Ai Medical Center, Department of Radiology, Oita 870-1151, Japan
- Department of Radiology, Shin-Beppu Hospital, Beppu 874-8538, Japan
| | - Mika Okahara
- Department of Radiology, Faculty of Medicine, Oita University, Yufu 879-5593, Japan; (S.T.); (R.T.); (M.O.)
- Department of Radiology, Shin-Beppu Hospital, Beppu 874-8538, Japan
| | - Saori Sugi Ueda
- Department of Gastroenterology, Shin-Beppu Hospital, Beppu 874-8538, Japan;
- San-Ai Medical Center, Department of Gastroenterology, Oita 870-115, Japan
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3
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Edwards DM, Speers C, Wahl DR. Targeting Noncanonical Regulators of the DNA Damage Response to Selectively Overcome Cancer Radiation Resistance. Semin Radiat Oncol 2021; 32:64-75. [PMID: 34861997 DOI: 10.1016/j.semradonc.2021.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Donna M Edwards
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Radiation Oncology, Rogel Cancer Center, Ann Arbor, MI
| | - Corey Speers
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Radiation Oncology, Rogel Cancer Center, Ann Arbor, MI
| | - Daniel R Wahl
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Radiation Oncology, Rogel Cancer Center, Ann Arbor, MI.
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4
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Magin S, Meher PK, Iliakis G. Nucleoside Analogs Radiosensitize G0 Cells by Activating DNA End Resection and Alternative End-Joining. Radiat Res 2021; 195:412-426. [PMID: 33755161 DOI: 10.1667/rade-20-00195.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 02/22/2021] [Indexed: 11/03/2022]
Abstract
Alternative end-joining (alt-EJ) is a DNA end resection-dependent, error-prone pathway utilized by vertebrate cells to repair DNA double-strand breaks (DSBs), but its engagement is linked to chromosomal translocations and genomic instability. Here, we report that when proliferating cells are exposed to ionizing radiation, treatment with nucleoside analogs (NAs) causes strong radiosensitization by increasing engagement of alt-EJ, while at the same time suppressing homologous recombination (HR) in S- and G2phase cells. This NA-mediated pathway shift may reflect a passive compensatory engagement of alt-EJ following HR suppression that is specific for S- and G2-phase cells, and/or the direct activation of alt-EJ throughout the cell cycle. To distinguish between these possibilities, we utilize here a cell culture model that exploits genetic and cell cycle-dependent inactivation of DSB repair pathways, to exclusively study alt-EJ and its modulation by NAs in murine and human cell lines. To this end, we allow LIG4-/--deficient cells to accumulate in G1/G0 phase by transfer to serum-deprived media and obtain cells deficient in c-NHEJ owing to the genetic LIG4 knockout, deficient in HR owing to the absence of S- or G2-phase cells, and compromised in their ability to carry out alt-EJ owing to their accumulation in G0. We find that in these cells irradiation and treatment with the NA, β-arabinofuranosyladenine (araA), and to a lesser degree with other NAs, promptly activates suppressed alt-EJ that now functions at levels approximating those of c-NHEJ in wild-type cells. Results at high dose (20 Gy) generated using pulsed-field gel electrophoresis (PFGE) are corroborated by results at low dose (1 Gy) generated by scoring 53BP1 foci. Strikingly, araA treatment activates a normally undetectable DNA-end-resection at DSBs, which requires ATR activity, but proceeds unimpeded after CtIP knockdown. Treatment with araA increases the formation of chromosomal aberrations and enhances radiation-induced cell killing. The results support direct stimulation of resection by NAs and alt-EJ as a mechanism of their documented radiosensitizing potential. We propose that this stimulation also occurs in repair-proficient cells and that it occurs throughout the cell cycle. It may therefore be harnessed to develop protocols combining NAs with radiation to treat human cancer.
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Affiliation(s)
- Simon Magin
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Prabodha Kumar Meher
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
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5
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Deycmar S, Faccin E, Kazimova T, Knobel PA, Telarovic I, Tschanz F, Waller V, Winkler R, Yong C, Zingariello D, Pruschy M. The relative biological effectiveness of proton irradiation in dependence of DNA damage repair. Br J Radiol 2019; 93:20190494. [PMID: 31687835 DOI: 10.1259/bjr.20190494] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Clinical parameters and empirical evidence are the primary determinants for current treatment planning in radiation oncology. Personalized medicine in radiation oncology is only at the very beginning to take the genetic background of a tumor entity into consideration to define an individual treatment regimen, the total dose or the combination with a specific anticancer agent. Likewise, stratification of patients towards proton radiotherapy is linked to its physical advantageous energy deposition at the tumor site with minimal healthy tissue being co-irradiated distal to the target volume. Hence, the fact that photon and proton irradiation also induce different qualities of DNA damages, which require differential DNA damage repair mechanisms has been completely neglected so far. These subtle differences could be efficiently exploited in a personalized treatment approach and could be integrated into personalized treatment planning. A differential requirement of the two major DNA double-strand break repair pathways, homologous recombination and non-homologous end joining, was recently identified in response to proton and photon irradiation, respectively, and subsequently influence the mode of ionizing radiation-induced cell death and susceptibility of tumor cells with defects in DNA repair machineries to either quality of ionizing radiation.This review focuses on the differential DNA-damage responses and subsequent biological processes induced by photon and proton irradiation in dependence of the genetic background and discusses their impact on the unicellular level and in the tumor microenvironment and their implications for combined treatment modalities.
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Affiliation(s)
- Simon Deycmar
- Laboratory for Applied Radiobiology Department of Radiation Oncology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland
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6
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Deycmar S, Pruschy M. Combined Treatment Modalities for High-Energy Proton Irradiation: Exploiting Specific DNA Repair Dependencies. Int J Part Ther 2018; 5:133-139. [DOI: 10.14338/ijpt-18-00020.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/05/2018] [Indexed: 11/21/2022] Open
Affiliation(s)
- Simon Deycmar
- Department of Radiation Oncology, Laboratory for Applied Radiobiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Martin Pruschy
- Department of Radiation Oncology, Laboratory for Applied Radiobiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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7
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Matulonis UA, Monk BJ. PARP inhibitor and chemotherapy combination trials for the treatment of advanced malignancies: does a development pathway forward exist? Ann Oncol 2018; 28:443-447. [PMID: 28057663 DOI: 10.1093/annonc/mdw697] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- U A Matulonis
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - B J Monk
- Arizona Oncology (US Oncology Network), University of Arizona and Creighton University Phoenix, Phoenix, AZ, USA
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8
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Vriend LE, van den Tempel N, Oei AL, L’Acosta M, Pieterson FJ, Franken NA, Kanaar R, Krawczyk PM. Boosting the effects of hyperthermia-based anticancer treatments by HSP90 inhibition. Oncotarget 2017; 8:97490-97503. [PMID: 29228626 PMCID: PMC5722578 DOI: 10.18632/oncotarget.22142] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 08/26/2017] [Indexed: 12/11/2022] Open
Abstract
Hyperthermia - application of supra-physiological temperatures to cells, tissues or organs - is a pleiotropic treatment that affects most aspects of cellular metabolism, but its effects on DNA are of special interest in the context of cancer research and treatment. Hyperthermia inhibits repair of various DNA lesions, including double-strand breaks (DSBs), making it a powerful radio- and chemosensitizer, with proven clinical efficacy in therapy of various types of cancer, including tumors of head and neck, bladder, breast and cervix. Among the challenges for hyperthermia-based therapies are the transient character of its effects, the technical difficulties in maintaining uniformly elevated tumor temperature and the acquisition of thermotolerance. Approaches to reduce or eliminate these challenges could simplify the application of hyperthermia, boost its efficacy and improve treatment outcomes. Here we show that a single, short treatment with a relatively low dose of HSP90 inhibitor Ganetespib potentiates cytotoxic as well as radio- and chemosensitizing effects of hyperthermia and reduces thermotolerance in cervix cancer cell lines. Ganetespib alone, applied at this low dose, has virtually no effect on survival of non-heated cells. Our results thus suggest that HSP90 inhibition can be a safe, simple and efficient approach to improving hyperthermia treatment efficacy and reducing thermotolerance, paving the way for in vivo studies.
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Affiliation(s)
- Lianne E.M. Vriend
- Department of Medical Biology, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Department of Radiation Oncology, Laboratory of Experimental Oncology and Radiobiology (LEXOR), Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Nathalie van den Tempel
- Department of Molecular Genetics, Cancer Genomics Center Netherlands, Department of Radiation Oncology, Erasmus Medical Center, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Arlene L. Oei
- Department of Radiation Oncology, Laboratory of Experimental Oncology and Radiobiology (LEXOR), Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Mike L’Acosta
- Department of Medical Biology, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | | | - Nicolaas A.P. Franken
- Department of Radiation Oncology, Laboratory of Experimental Oncology and Radiobiology (LEXOR), Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Cancer Genomics Center Netherlands, Department of Radiation Oncology, Erasmus Medical Center, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Przemek M. Krawczyk
- Department of Medical Biology, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Department of Radiation Oncology, Laboratory of Experimental Oncology and Radiobiology (LEXOR), Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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9
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Sarkisjan D, van den Berg J, Smit E, Lee YB, Kim DJ, Peters GJ. The radiosensitizing effect of fluorocyclopentenyl-cytosine (RX-3117) in ovarian and lung cancer cell lines. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 35:619-630. [PMID: 27906620 DOI: 10.1080/15257770.2016.1216565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RX-3117 (fluorocyclopentenyl-cytosine) is a novel cytidine analog currently being evaluated in a Phase Ib clinical trial in cancer patients with solid tumors. The radiosensitizing effect of RX-3117 was studied in A2780 ovarian cancer cells and non-small cell lung cancer cell lines and related to cell survival and the effect on cell cycle and cell cycle proteins. RX-3117 has a schedule-dependent radiosensitizing effect, but only at pre-incubation (dose modifying factors: 1.4-1.8), observed at pulse and fractionated irradiation. Radiosensitizion was also seen in a three-dimensional spheroid model. At the low radiosensitizing concentration, RX-3117 in combination with radiation led to an accumulation of cells in S-phase, which was accompanied with an increase of cell cycle proteins such as p-Chk2 and p-cdc25C. In addition, RX-3117 caused DNA damage and increased apoptosis. In conclusion, our in vitro experiments showed a radiosensitizing effect of RX-3117.
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Affiliation(s)
- Dzjemma Sarkisjan
- a Department of Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands
| | - Jaap van den Berg
- b Department of Radio Therapy , VU University Medical Center , Amsterdam , The Netherlands
| | - Evelyn Smit
- a Department of Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands
| | - Young B Lee
- c Rexahn Pharmaceuticals, Inc. , Rockville , Maryland , USA
| | - Deog J Kim
- c Rexahn Pharmaceuticals, Inc. , Rockville , Maryland , USA
| | - Godefridus J Peters
- a Department of Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands
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10
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Im MM, Flanagan SA, Ackroyd JJ, Knapp B, Kramer A, Shewach DS. Late DNA Damage Mediated by Homologous Recombination Repair Results in Radiosensitization with Gemcitabine. Radiat Res 2016; 186:466-477. [PMID: 27740890 DOI: 10.1667/rr14443.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Gemcitabine (dFdCyd) shows broad antitumor activity in solid tumors in chemotherapeutic regimens or when combined with ionizing radiation (radiosensitization). While it is known that mismatches in DNA are necessary for dFdCyd radiosensitization, the critical event resulting in radiosensitization has not been identified. Here we hypothesized that late DNA damage (≥24 h after drug washout/irradiation) is a causal event in radiosensitization by dFdCyd, and that homologous recombination repair (HRR) is required for this late DNA damage. Using γ-H2AX as a measurement of DNA damage in MCF-7 breast cancer cells, we demonstrate that 10 or 80 nM dFdCyd alone produced significantly more late DNA damage compared to that observed within 4 h after treatment. The combination of dFdCyd treatment followed by irradiation did not produce a consistent increase in DNA damage in the first 4 h after treatment, however, there was a synergistic increase 24-48 h later relative to treatment with dFdCyd or radiation alone. RNAi suppression of the essential HRR protein, XRCC3, significantly decreased both radiosensitization and late DNA damage. Furthermore, inhibition of HRR with the Rad51 inhibitor B02 prevented radiosensitization when added after, but not during, treatment with dFdCyd and radiation. To our knowledge, this is the first published study to show that radiosensitization with dFdCyd results from a synergistic increase in DNA damage at 24-48 h after drug and radiation treatment, and that this damage and radiosensitization require HRR. These results suggest that tumors that overexpress HRR will be more vulnerable to chemoradiotherapy, and treatments that increase HRR and/or mismatches in DNA will enhance dFdCyd radiosensitization.
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Affiliation(s)
- Michael M Im
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Sheryl A Flanagan
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Jeffrey J Ackroyd
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Brendan Knapp
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Aaron Kramer
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Donna S Shewach
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
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11
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Gaudin A, Song E, King AR, Saucier-Sawyer JK, Bindra R, Desmaële D, Couvreur P, Saltzman WM. PEGylated squalenoyl-gemcitabine nanoparticles for the treatment of glioblastoma. Biomaterials 2016; 105:136-144. [PMID: 27521616 DOI: 10.1016/j.biomaterials.2016.07.037] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 07/27/2016] [Accepted: 07/29/2016] [Indexed: 11/25/2022]
Abstract
New treatments for glioblastoma multiforme (GBM) are desperately needed, as GBM prognosis remains poor, mainly due to treatment resistance, poor distribution of therapeutics in the tumor tissue, and fast metabolism of chemotherapeutic drugs in the brain extracellular space. Convection-enhanced delivery (CED) of nanoparticles (NPs) has been shown to improve the delivery of chemotherapeutic drugs to the tumor bed, providing sustained release, and enhancing survival of animals with intracranial tumors. Here we administered gemcitabine, a nucleoside analog used as a first line treatment for a wide variety of extracranial solid tumors, within squalene-based NPs using CED, to overcome the above-mentioned challenges of GBM treatment. Small percentages of poly(ethylene) glycol (PEG) dramatically enhanced the distribution of squalene-gemcitabine nanoparticles (SQ-Gem NPs) in healthy animals and tumor-bearing animals after administration by CED. When tested in an orthotopic model of GBM, SQ-Gem-PEG NPs demonstrated significantly improved therapeutic efficacy compared to free gemcitabine, both as a chemotherapeutic drug and as a radiosensitizer. Furthermore, MR contrast agents were incorporated into the SQ-Gem-PEG NP formulation, providing a way to non-invasively track the NPs during infusion.
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Affiliation(s)
- Alice Gaudin
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06511, USA
| | - Eric Song
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06511, USA
| | - Amanda R King
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06511, USA
| | | | - Ranjit Bindra
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, 06511, USA
| | - Didier Desmaële
- Institut Galien Paris-Sud, UMR CNRS 8612, University Paris-Sud XI, Châtenay-Malabry, 92290, France
| | - Patrick Couvreur
- Institut Galien Paris-Sud, UMR CNRS 8612, University Paris-Sud XI, Châtenay-Malabry, 92290, France
| | - W Mark Saltzman
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06511, USA.
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12
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Cell-cycle-controlled radiation therapy was effective for treating a murine malignant melanoma cell line in vitro and in vivo. Sci Rep 2016; 6:30689. [PMID: 27480052 PMCID: PMC4969753 DOI: 10.1038/srep30689] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 07/07/2016] [Indexed: 01/06/2023] Open
Abstract
Radiotherapy is a commonly used regimen for treating various types of intractable cancers, although the effects depend on the cell cycle of the targeted cancer cell lines, and for irradiation purposes it is therefore critical to establish a protocol for controlling the cell cycle. Here, we showed that a common murine melanoma cell line B16BL6 was more vulnerable to irradiation during the early S phase, and that synchronisation of the cell cycle greatly increased the therapeutic effects of radiotherapy. Cell-sorting experiments, according to cell-cycle phase, using B16BL6 cells demonstrated that cells in the early S phase were the most susceptible to radiotherapy. Gemcitabine, a clinically utilised anti-cancer drug, induced cell-cycle arrest during the early S phase in B16BL6 cells, and thus a synergistic therapeutic effect was observed when irradiation was administered at the right time. Human pancreatic cancer cell line PANC-1 exhibited similar properties to B16BL6 in terms of its radiosensitivity during the S/G2/M phase and also demonstrated a synergistic effect of cell cycle synchronisation. These results show the importance of cell-cycle control in the application of irradiation and suggest a suitable time interval between chemotherapy and radiotherapy, as well as providing useful information for treating intractable cancer.
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13
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Effects of hyperthermia as a mitigation strategy in DNA damage-based cancer therapies. Semin Cancer Biol 2016; 37-38:96-105. [PMID: 27025900 DOI: 10.1016/j.semcancer.2016.03.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 03/25/2016] [Accepted: 03/25/2016] [Indexed: 12/25/2022]
Abstract
Utilization of thermal therapy (hyperthermia) is defined as the application of exogenous heat induction and represents a concept that is far from new as it goes back to ancient times when heat was used for treating various diseases, including malignancies. Such therapeutic strategy has gained even more popularity (over the last few decades) since various studies have shed light into understanding hyperthermia's underlying molecular mechanism(s) of action. In general, hyperthermia is applied as complementary (adjuvant) means in therapeutic protocols combining chemotherapy and/or irradiation both of which can induce irreversible cellular DNA damage. Furthermore, according to a number of in vitro, in vivo and clinical studies, hyperthermia has been shown to enhance the beneficial effects of DNA targeting therapeutic strategies by interfering with DNA repair response cascades. Therefore, the continuously growing evidence supporting hyperthermia's beneficial role in cancer treatment can also encourage its application as a DNA repair mitigation strategy. In this review article, we aim to provide detailed information on how hyperthermia acts on DNA damage and repair pathways and thus potentially contributing to various adjuvant therapeutic protocols relevant to more efficient cancer treatment strategies.
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Harrabi SB, Adeberg S, Winter M, Haberer T, Debus J, Weber KJ. S-phase-specific radiosensitization by gemcitabine for therapeutic carbon ion exposure in vitro. JOURNAL OF RADIATION RESEARCH 2016; 57:110-114. [PMID: 26747201 PMCID: PMC4795954 DOI: 10.1093/jrr/rrv097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 08/27/2015] [Accepted: 10/19/2015] [Indexed: 06/05/2023]
Abstract
Densely ionizing charged particle irradiation offers physical as well as biological advantages compared with photon irradiation. Radiobiological data for the combination of such particle irradiation (i.e. therapeutic carbon ions) with commonly used chemotherapeutics are still limited. Recent in vitro results indicate a general prevalence of additive cytotoxic effects in combined treatments, but an extension of established multimodal treatment regimens with photons to the inclusion of particle therapy needs to evaluate possible peculiarities of using high linear energy transfer (LET) radiation. The present study investigates the effect of combined radiochemotherapy using gemcitabine and high-LET irradiation with therapeutic carbon ions. In particular, the earlier observation of S-phase specific radiosensitization with photon irradiation should be evaluated with carbon ions. In the absence of the drug gemcitabine, carbon ion irradiation produced the typical survival behavior seen with X-rays-increased relative biological efficiency, and depletion of the survival curve's shoulder. By means of serum deprivation and subsequent replenishment, ∼70% S-phase content of the cell population was achieved, and such preparations showed radioresistance in both treatment arms-,photon and carbon ion irradiation. Combined modality treatment with gemcitabine caused significant reduction of clonogenic survival especially for the S-phase cells. WIDR cells exhibited S-phase-specific radioresistance with high-LET irradiation, although this was less pronounced than for X-ray exposure. The combined treatment with therapeutic carbon ions and gemcitabine caused the resistance phenomenon to disappear phenotypically.
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Affiliation(s)
- Semi B Harrabi
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany Heidelberg Ion Therapy Center (HIT), Im Neuenheimer Feld 450, Heidelberg 69120, Germany
| | - Sebastian Adeberg
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany
| | - Marcus Winter
- Heidelberg Ion Therapy Center (HIT), Im Neuenheimer Feld 450, Heidelberg 69120, Germany
| | - Thomas Haberer
- Heidelberg Ion Therapy Center (HIT), Im Neuenheimer Feld 450, Heidelberg 69120, Germany
| | - Jürgen Debus
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany Heidelberg Ion Therapy Center (HIT), Im Neuenheimer Feld 450, Heidelberg 69120, Germany
| | - Klaus-Josef Weber
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany
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Weaver AN, Cooper TS, Rodriguez M, Trummell HQ, Bonner JA, Rosenthal EL, Yang ES. DNA double strand break repair defect and sensitivity to poly ADP-ribose polymerase (PARP) inhibition in human papillomavirus 16-positive head and neck squamous cell carcinoma. Oncotarget 2015; 6:26995-7007. [PMID: 26336991 PMCID: PMC4694969 DOI: 10.18632/oncotarget.4863] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 08/12/2015] [Indexed: 01/04/2023] Open
Abstract
Patients with human papillomavirus-positive (HPV+) head and neck squamous cell carcinomas (HNSCCs) have increased response to radio- and chemotherapy and improved overall survival, possibly due to an impaired DNA damage response. Here, we investigated the correlation between HPV status and repair of DNA damage in HNSCC cell lines. We also assessed in vitro and in vivo sensitivity to the PARP inhibitor veliparib (ABT-888) in HNSCC cell lines and an HPV+ patient xenograft. Repair of DNA double strand breaks (DSBs) was significantly delayed in HPV+ compared to HPV- HNSCCs, resulting in persistence of γH2AX foci. Although DNA repair activators 53BP1 and BRCA1 were functional in all HNSCCs, HPV+ cells showed downstream defects in both non-homologous end joining and homologous recombination repair. Specifically, HPV+ cells were deficient in protein recruitment and protein expression of DNA-Pk and BRCA2, key factors for non-homologous end joining and homologous recombination respectively. Importantly, the apparent DNA repair defect in HPV+ HNSCCs was associated with increased sensitivity to the PARP inhibitor veliparib, resulting in decreased cell survival in vitro and a 10-14 day tumor growth delay in vivo. These results support the testing of PARP inhibition in combination with DNA damaging agents as a novel therapeutic strategy for HPV+ HNSCC.
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Affiliation(s)
- Alice N. Weaver
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Tiffiny S. Cooper
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Marcela Rodriguez
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Hoa Q. Trummell
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - James A. Bonner
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Eben L. Rosenthal
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35249, USA
| | - Eddy S. Yang
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35249, USA
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Oei AL, Vriend LEM, Crezee J, Franken NAP, Krawczyk PM. Effects of hyperthermia on DNA repair pathways: one treatment to inhibit them all. Radiat Oncol 2015; 10:165. [PMID: 26245485 PMCID: PMC4554295 DOI: 10.1186/s13014-015-0462-0] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/13/2015] [Indexed: 12/03/2022] Open
Abstract
The currently available arsenal of anticancer modalities includes many DNA damaging agents that can kill malignant cells. However, efficient DNA repair mechanisms protect both healthy and cancer cells against the effects of treatment and contribute to the development of drug resistance. Therefore, anti-cancer treatments based on inflicting DNA damage can benefit from inhibition of DNA repair. Hyperthermia – treatment at elevated temperature – considerably affects DNA repair, among other cellular processes, and can thus sensitize (cancer) cells to DNA damaging agents. This effect has been known and clinically applied for many decades, but how heat inhibits DNA repair and which pathways are targeted has not been fully elucidated. In this review we attempt to summarize the known effects of hyperthermia on DNA repair pathways relevant in clinical treatment of cancer. Furthermore, we outline the relationships between the effects of heat on DNA repair and sensitization of cells to various DNA damaging agents.
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Affiliation(s)
- Arlene L Oei
- Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands. .,Department of Radiotherapy, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands.
| | - Lianne E M Vriend
- Van Leeuwenhoek Centre for Advanced Microscopy (LCAM)-AMC, Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
| | - Johannes Crezee
- Department of Radiotherapy, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands.
| | - Nicolaas A P Franken
- Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands. .,Department of Radiotherapy, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands.
| | - Przemek M Krawczyk
- Van Leeuwenhoek Centre for Advanced Microscopy (LCAM)-AMC, Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
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Haeger SM, Thompson JJ, Kalra S, Cleaver TG, Merrick D, Wang XJ, Malkoski SP. Smad4 loss promotes lung cancer formation but increases sensitivity to DNA topoisomerase inhibitors. Oncogene 2015; 35:577-586. [PMID: 25893305 PMCID: PMC4615192 DOI: 10.1038/onc.2015.112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 02/21/2015] [Accepted: 03/09/2015] [Indexed: 01/03/2023]
Abstract
Non-small cell lung cancer (NSCLC) is a common malignancy with a poor prognosis. Despite progress targeting oncogenic drivers, there are no therapies targeting tumor suppressor loss. Smad4 is an established tumor suppressor in pancreatic and colon cancer, however, the consequences of Smad4 loss in lung cancer are largely unknown. We evaluated Smad4 expression in human NSCLC samples and examined Smad4 alterations in large NSCLC datasets and found that reduced Smad4 expression is common in human NSCLC and occurs through a variety of mechanisms including mutation, homozygous deletion, and heterozygous loss. We modeled Smad4 loss in lung cancer by deleting Smad4 in airway epithelial cells and found that Smad4 deletion both initiates and promotes lung tumor development. Interestingly, both Smad4−/− mouse tumors and human NSCLC samples with reduced Smad4 expression demonstrated increased DNA damage while Smad4 knockdown in lung cancer cells reduced DNA repair and increased apoptosis after DNA damage. In addition, Smad4 deficient NSCLC cells demonstrated increased sensitivity to both chemotherapeutics that inhibit DNA topoisomerase and drugs that block double strand DNA break repair by non-homologous end joining. In sum, these studies establish Smad4 as a lung tumor suppressor and suggest that the defective DNA repair phenotype of Smad4 deficient tumors can be exploited by specific therapeutic strategies.
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Affiliation(s)
- Sarah M Haeger
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Joshua J Thompson
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Sean Kalra
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Timothy G Cleaver
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Daniel Merrick
- Department of Pathology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Xiao-Jing Wang
- Department of Pathology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
| | - Stephen P Malkoski
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO.,Department of Pathology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO
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Magin S, Papaioannou M, Saha J, Staudt C, Iliakis G. Inhibition of Homologous Recombination and Promotion of Mutagenic Repair of DNA Double-Strand Breaks Underpins Arabinoside–Nucleoside Analogue Radiosensitization. Mol Cancer Ther 2015; 14:1424-33. [DOI: 10.1158/1535-7163.mct-14-0682] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 03/22/2015] [Indexed: 11/16/2022]
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Im MM, Flanagan SA, Ackroyd JJ, Shewach DS. Drug metabolism and homologous recombination repair in radiosensitization with gemcitabine. Radiat Res 2015; 183:114-23. [PMID: 25564718 DOI: 10.1667/rr13807.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Gemcitabine (difluorodeoxycytidine; dFdCyd) is a potent radiosensitizer, noted for its ability to enhance cytotoxicity with radiation at noncytotoxic concentrations in vitro and subchemotherapeutic doses in patients. Radiosensitization in human tumor cells requires dFdCyd-mediated accumulation of cells in S phase with inhibition of ribonucleotide reductase, resulting in ≥80% deoxyadenosine triphosphate (dATP) depletion and errors of replication in DNA. Less is known of the role of specific DNA replication and repair pathways in the radiosensitization mechanism. Here the role of homologous recombination (HR) in relationship to the metabolic and cell cycle effects of dFdCyd was investigated using a matched pair of CHO cell lines that are either proficient (AA8 cells) or deficient (irs1SF cells) in HR based on expression of the HR protein XRCC3. The results demonstrated that the characteristics of radiosensitization in the rodent AA8 cells differed significantly from those in human tumor cells. In the AA8 cells, radiosensitization was achieved only under short (≤4 h) cytotoxic incubations, and S-phase accumulation did not appear to be required for radiosensitization. In contrast, human tumor cell lines were radiosensitized using noncytotoxic concentrations of dFdCyd and required early S-phase accumulation. Studies of the metabolic effects of dFdCyd demonstrated low dFdCyd concentrations did not deplete dATP by ≥80% in AA8 and irs1SF cells. However, at higher concentrations of dFdCyd, failure to radiosensitize the HR-deficient irs1SF cells could not be explained by a lack of dATP depletion or lack of S-phase accumulation. Thus, these parameters did not correspond to dFdCyd radiosensitization in the CHO cells. To evaluate directly the role of HR in radiosensitization, XRCC3 expression was suppressed in the AA8 cells with a lentiviral-delivered shRNA. Partial XRCC3 suppression significantly decreased radiosensitization [radiation enhancement ratio (RER) = 1.6 ± 0.15], compared to nontransduced (RER = 2.7 ± 0.27; P = 0.012), and a substantial decrease compared to nonspecific shRNA-transduced (RER = 2.5 ± 0.42; P = 0.056) AA8 cells. Although the results support a role for HR in radiosensitization with dFdCyd in CHO cells, the differences in the underlying metabolic and cell cycle characteristics suggest that dFdCyd radiosensitization in the nontumor-derived CHO cells is mechanistically distinct from that in human tumor cells.
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Affiliation(s)
- Michael M Im
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
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20
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Haynes B, Saadat N, Myung B, Shekhar MPV. Crosstalk between translesion synthesis, Fanconi anemia network, and homologous recombination repair pathways in interstrand DNA crosslink repair and development of chemoresistance. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 763:258-66. [PMID: 25795124 DOI: 10.1016/j.mrrev.2014.11.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/10/2014] [Accepted: 11/11/2014] [Indexed: 12/12/2022]
Abstract
Bifunctional alkylating and platinum based drugs are chemotherapeutic agents used to treat cancer. These agents induce DNA adducts via formation of intrastrand or interstrand (ICL) DNA crosslinks, and DNA lesions of the ICL type are particularly toxic as they block DNA replication and/or DNA transcription. However, the therapeutic efficacies of these drugs are frequently limited due to the cancer cell's enhanced ability to repair and tolerate these toxic DNA lesions. This ability to tolerate and survive the DNA damage is accomplished by a set of specialized low fidelity DNA polymerases called translesion synthesis (TLS) polymerases since high fidelity DNA polymerases are unable to replicate the damaged DNA template. TLS is a crucial initial step in ICL repair as it synthesizes DNA across the lesion thus preparing the damaged DNA template for repair by the homologous recombination (HR) pathway and Fanconi anemia (FA) network, processes critical for ICL repair. Here we review the molecular features and functional roles of TLS polymerases, discuss the collaborative interactions and cross-regulation of the TLS DNA damage tolerance pathway, the FA network and the BRCA-dependent HRR pathway, and the impact of TLS hyperactivation on development of chemoresistance. Finally, since TLS hyperactivation results from overexpression of Rad6/Rad18 ubiquitinating enzymes (fundamental components of the TLS pathway), increased PCNA ubiquitination, and/or increased recruitment of TLS polymerases, the potential benefits of selectively targeting critical components of the TLS pathway for enhancing anti-cancer therapeutic efficacy and curtailing chemotherapy-induced mutagenesis are also discussed.
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Affiliation(s)
- Brittany Haynes
- Department of Oncology, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States; Karmanos Cancer Institute, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States
| | - Nadia Saadat
- Department of Oncology, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States; Karmanos Cancer Institute, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States
| | - Brian Myung
- Karmanos Cancer Institute, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States
| | - Malathy P V Shekhar
- Department of Oncology, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States; Karmanos Cancer Institute, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States; Department of Pathology, Wayne State University, 110 East Warren Avenue, Detroit, MI 48201, United States.
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Lee MW, Parker WB, Xu B. New insights into the synergism of nucleoside analogs with radiotherapy. Radiat Oncol 2013; 8:223. [PMID: 24066967 PMCID: PMC3851323 DOI: 10.1186/1748-717x-8-223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/24/2013] [Indexed: 11/18/2022] Open
Abstract
Nucleoside analogs have been frequently used in combination with radiotherapy in the clinical setting, as it has long been understood that inhibition of DNA repair pathways is an important means by which many nucleoside analogs synergize. Recent advances in our understanding of the structure and function of deoxycytidine kinase (dCK), a critical enzyme required for the anti-tumor activity for many nucleoside analogs, have clarified the mechanistic role this kinase plays in chemo- and radio-sensitization. A heretofore unrecognized role of dCK in the DNA damage response and cell cycle machinery has helped explain the synergistic effect of these agents with radiotherapy. Since most currently employed nucleoside analogs are primarily activated by dCK, these findings lend fresh impetus to efforts focused on profiling and modulating dCK expression and activity in tumors. In this review we will briefly review the pharmacology and biochemistry of the major nucleoside analogs in clinical use that are activated by dCK. This will be followed by discussions of recent advances in our understanding of dCK activation via post-translational modifications in response to radiation and current strategies aimed at enhancing this activity in cancer cells.
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Affiliation(s)
- Michael W Lee
- Department of Medical Education, College of Medicine, University of Central Florida, 6850 Lake Nona Blvd,, Orlando, FL 32827, USA.
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22
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Mladenov E, Magin S, Soni A, Iliakis G. DNA double-strand break repair as determinant of cellular radiosensitivity to killing and target in radiation therapy. Front Oncol 2013; 3:113. [PMID: 23675572 PMCID: PMC3650303 DOI: 10.3389/fonc.2013.00113] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/24/2013] [Indexed: 12/29/2022] Open
Abstract
Radiation therapy plays an important role in the management of a wide range of cancers. Besides innovations in the physical application of radiation dose, radiation therapy is likely to benefit from novel approaches exploiting differences in radiation response between normal and tumor cells. While ionizing radiation induces a variety of DNA lesions, including base damages and single-strand breaks, the DNA double-strand break (DSB) is widely considered as the lesion responsible not only for the aimed cell killing of tumor cells, but also for the general genomic instability that leads to the development of secondary cancers among normal cells. Homologous recombination repair (HRR), non-homologous end-joining (NHEJ), and alternative NHEJ, operating as a backup, are the major pathways utilized by cells for the processing of DSBs. Therefore, their function represents a major mechanism of radiation resistance in tumor cells. HRR is also required to overcome replication stress – a potent contributor to genomic instability that fuels cancer development. HRR and alternative NHEJ show strong cell-cycle dependency and are likely to benefit from radiation therapy mediated redistribution of tumor cells throughout the cell-cycle. Moreover, the synthetic lethality phenotype documented between HRR deficiency and PARP inhibition has opened new avenues for targeted therapies. These observations make HRR a particularly intriguing target for treatments aiming to improve the efficacy of radiation therapy. Here, we briefly describe the major pathways of DSB repair and review their possible contribution to cancer cell radioresistance. Finally, we discuss promising alternatives for targeting DSB repair to improve radiation therapy and cancer treatment.
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Affiliation(s)
- Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School Essen, Germany
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Yong KJ, Milenic DE, Baidoo KE, Brechbiel MW. Sensitization of tumor to ²¹²Pb radioimmunotherapy by gemcitabine involves initial abrogation of G2 arrest and blocked DNA damage repair by interference with Rad51. Int J Radiat Oncol Biol Phys 2013; 85:1119-26. [PMID: 23200172 PMCID: PMC3594422 DOI: 10.1016/j.ijrobp.2012.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 09/05/2012] [Accepted: 09/14/2012] [Indexed: 12/22/2022]
Abstract
PURPOSE To elucidate the mechanism of the therapeutic efficacy of targeted α-particle radiation therapy using (212)Pb-TCMC-trastuzumab together with gemcitabine for treatment of disseminated peritoneal cancers. METHODS AND MATERIALS Mice bearing human colon cancer LS-174T intraperitoneal xenografts were pretreated with gemcitabine, followed by (212)Pb-TCMC-trastuzumab and compared with controls. RESULTS Treatment with (212)Pb-TCMC-trastuzumab increased the apoptotic rate in the S-phase-arrested tumors induced by gemcitabine at earlier time points (6 to 24 hours). (212)Pb-TCMC-trastuzumab after gemcitabine pretreatment abrogated G2/M arrest at the same time points, which may be associated with the inhibition of Chk1 phosphorylation and, in turn, cell cycle perturbation, resulting in apoptosis. (212)Pb-TCMC-trastuzumab treatment after gemcitabine pretreatment caused depression of DNA synthesis, DNA double-strand breaks, accumulation of unrepaired DNA, and down-regulation of Rad51 protein, indicating that DNA damage repair was blocked. In addition, modification in the chromatin structure of p21 may be associated with transcriptionally repressed chromatin states, indicating that the open structure was delayed at earlier time points. CONCLUSION These findings suggest that the cell-killing efficacy of (212)Pb-TCMC-trastuzumab after gemcitabine pretreatment may be associated with abrogation of the G2/M checkpoint, inhibition of DNA damage repair, and chromatin remodeling.
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Affiliation(s)
- Kwon Joong Yong
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda MD
| | - Diane E. Milenic
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda MD
| | - Kwamena E. Baidoo
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda MD
| | - Martin W. Brechbiel
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda MD
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FRANKEN NICOLAASA, OEI ARLENEL, KOK HPETRA, RODERMOND HANSM, SMINIA PETER, CREZEE JOHANNES, STALPERS LUKASJ, BARENDSEN GERRITW. Cell survival and radiosensitisation: Modulation of the linear and quadratic parameters of the LQ model. Int J Oncol 2013; 42:1501-15. [DOI: 10.3892/ijo.2013.1857] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 12/21/2012] [Indexed: 11/05/2022] Open
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Soo RA, Yong WP, Innocenti F. Systemic therapies for pancreatic cancer--the role of pharmacogenetics. Curr Drug Targets 2012; 13:811-28. [PMID: 22458528 DOI: 10.2174/138945012800564068] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 02/23/2012] [Accepted: 03/27/2012] [Indexed: 12/17/2022]
Abstract
Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.
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Affiliation(s)
- Ross A Soo
- Department of Hematology-Oncology, National University Health System, Singapore
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26
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Soo RA, Yong WP, Innocenti F. Systemic therapies for pancreatic cancer--the role of pharmacogenetics. Curr Drug Targets 2012. [PMID: 22458528 DOI: 10.1016/j.pestbp.2011.02.012.investigations] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.
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Affiliation(s)
- Ross A Soo
- Department of Hematology-Oncology, National University Health System, Singapore
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27
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The impact of pharmacogenetics on radiation therapy outcome in cancer patients. A focus on DNA damage response genes. Cancer Treat Rev 2012; 38:737-59. [DOI: 10.1016/j.ctrv.2012.02.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 02/03/2012] [Accepted: 02/06/2012] [Indexed: 11/18/2022]
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Eppink B, Krawczyk PM, Stap J, Kanaar R. Hyperthermia-induced DNA repair deficiency suggests novel therapeutic anti-cancer strategies. Int J Hyperthermia 2012; 28:509-17. [PMID: 22834701 DOI: 10.3109/02656736.2012.695427] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Local hyperthermia is an effective treatment modality to augment radio- and chemotherapy-based anti-cancer treatments. Although the effect of hyperthermia is pleotropic, recent experiments revealed that homologous recombination, a pathway of DNA repair, is directly inhibited by hyperthermia. The hyperthermia-induced DNA repair deficiency is enhanced by inhibitors of the cellular heat-shock response. Taken together, these results provide the rationale for the development of novel anti-cancer therapies that combine hyperthermia-induced homologous recombination deficiency with the systemic administration of drugs that specifically affect the viability of homologous recombination deficient cells and/or inhibit the heat-shock response, to locally sensitise cancer cells to DNA damaging agents.
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Affiliation(s)
- Berina Eppink
- Department of Cell Biology and Genetics, Cancer Genomics Centre, Erasmus Medical Centre, Rotterdam, The Netherlands
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Meng F, Evans JW, Bhupathi D, Banica M, Lan L, Lorente G, Duan JX, Cai X, Mowday AM, Guise CP, Maroz A, Anderson RF, Patterson AV, Stachelek GC, Glazer PM, Matteucci MD, Hart CP. Molecular and cellular pharmacology of the hypoxia-activated prodrug TH-302. Mol Cancer Ther 2011; 11:740-51. [PMID: 22147748 DOI: 10.1158/1535-7163.mct-11-0634] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
TH-302 is a 2-nitroimidazole triggered hypoxia-activated prodrug (HAP) of bromo-isophosphoramide mustard currently undergoing clinical evaluation. Here, we describe broad-spectrum activity, hypoxia-selective activation, and mechanism of action of TH-302. The concentration and time dependence of TH-302 activation was examined as a function of oxygen concentration, with reference to the prototypic HAP tirapazamine, and showed superior oxygen inhibition of cytotoxicity and much improved dose potency relative to tirapazamine. Enhanced TH-302 cytotoxicity under hypoxia was observed across 32 human cancer cell lines. One-electron reductive enzyme dependence was confirmed using cells overexpressing human NADPH:cytochrome P450 oxidoreductase and radiolytic reduction established the single-electron stoichiometry of TH-302 fragmentation (activation). Examining downstream effects of TH-302 activity, we observed hypoxia-dependent induction of γH2AX phosphorylation, DNA cross-linking, and cell-cycle arrest. We used Chinese hamster ovary cell-based DNA repair mutant cell lines and established that lines deficient in homology-dependent repair, but not lines deficient in base excision, nucleotide excision, or nonhomologous end-joining repair, exhibited marked sensitivity to TH-302 under hypoxia. Consistent with this finding, enhanced sensitivity to TH-302 was also observed in lines deficient in BRCA1, BRCA2, and FANCA. Finally, we characterized TH-302 activity in the three-dimensional tumor spheroid and multicellular layer models. TH-302 showed much enhanced potency in H460 spheroids compared with H460 monolayer cells under normoxia. Multicellular layers composed of mixtures of parental HCT116 cells and HCT116 cells engineered to express an oxygen-insensitive bacterial nitroreductase showed that TH-302 exhibits a significant bystander effect.
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Affiliation(s)
- Fanying Meng
- Threshold Pharmaceuticals, 170 Harbor Way, Suite 300, South San Francisco, CA 94080, USA.
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The human immunodeficiency virus protease inhibitor ritonavir inhibits lung cancer cells, in part, by inhibition of survivin. J Thorac Oncol 2011; 6:661-70. [PMID: 21270666 DOI: 10.1097/jto.0b013e31820c9e3c] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Ritonavir is a potential therapeutic agent in lung cancer, but its targets in lung adenocarcinoma are unknown, as are candidate biomarkers for its activity. METHODS RNAi was used to identify genes whose expression affects ritonavir sensitivity. Synergy between ritonavir, gemcitabine, and cisplatin was tested by isobologram analysis. RESULTS Ritonavir inhibits growth of K-ras mutant lung adenocarcinoma lines A549, H522, H23, and K-ras wild-type line H838. Ritonavir causes G0/G1 arrest and apoptosis. Associated with G0/G1 arrest, ritonavir down-regulates cyclin-dependent kinases, cyclin D1, and retinoblastoma protein phosphorylation. Associated with induction of apoptosis, ritonavir reduces survivin messenger RNA and protein levels more than twofold. Ritonavir inhibits phosphorylation of c-Src and signal transducer and activator of transcription protein 3, which are important events for survivin gene expression and cell growth, and induces cleavage of PARP1. Although knock down of survivin, c-Src, or signal transducer and activator of transcription protein 3 inhibits cell growth, only survivin knock down enhances ritonavir inhibition of growth and survivin overexpression promotes ritonavir resistance. Ritonavir was tested in combination with gemcitabine or cisplatin, exhibiting synergistic and additive effects, respectively. The combination of ritonavir/gemcitabine/cisplatin is synergistic in the A549 line and additive in the H522 line, at clinically feasible ritonavir concentrations (<10 μM). CONCLUSIONS Ritonavir is of interest for lung adenocarcinoma therapeutics, and survivin is an important target and potential biomarker for its sensitivity. Ritonavir cooperation with gemcitabine/cisplatin might be explained by involvement of PARP1 in repair of cisplatin-mediated DNA damage and survivin in repair of gemcitabine-mediated double-stranded DNA breaks.
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Meike S, Yamamori T, Yasui H, Eitaki M, Matsuda A, Morimatsu M, Fukushima M, Yamasaki Y, Inanami O. A nucleoside anticancer drug, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (TAS106), sensitizes cells to radiation by suppressing BRCA2 expression. Mol Cancer 2011; 10:92. [PMID: 21798026 PMCID: PMC3161955 DOI: 10.1186/1476-4598-10-92] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 07/28/2011] [Indexed: 11/30/2022] Open
Abstract
Background A novel anticancer drug 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (ECyd, TAS106) has been shown to radiosensitize tumor cells and to improve the therapeutic efficiency of X-irradiation. However, the effect of TAS106 on cellular DNA repair capacity has not been elucidated. Our aim in this study was to examine whether TAS106 modified the repair capacity of DNA double-strand breaks (DSBs) in tumor cells. Methods Various cultured cell lines treated with TAS106 were irradiated and then survival fraction was examined by the clonogenic survival assays. Repair of sublethal damage (SLD), which indicates DSBs repair capacity, was measured as an increase of surviving cells after split dose irradiation with an interval of incubation. To assess the effect of TAS106 on the DSBs repair activity, the time courses of γ-H2AX and 53BP1 foci formation were examined by using immunocytochemistry. The expression of DNA-repair-related proteins was also examined by Western blot analysis and semi-quantitative RT-PCR analysis. Results In clonogenic survival assays, pretreatment of TAS106 showed radiosensitizing effects in various cell lines. TAS106 inhibited SLD repair and delayed the disappearance of γ-H2AX and 53BP1 foci, suggesting that DSB repair occurred in A549 cells. Western blot analysis demonstrated that TAS106 down-regulated the expression of BRCA2 and Rad51, which are known as keys among DNA repair proteins in the homologous recombination (HR) pathway. Although a significant radiosensitizing effect of TAS106 was observed in the parental V79 cells, pretreatment with TAS106 did not induce any radiosensitizing effects in BRCA2-deficient V-C8 cells. Conclusions Our results indicate that TAS106 induces the down-regulation of BRCA2 and the subsequent abrogation of the HR pathway, leading to a radiosensitizing effect. Therefore, this study suggests that inhibition of the HR pathway may be useful to improve the therapeutic efficiency of radiotherapy for solid tumors.
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Affiliation(s)
- Shunsuke Meike
- Laboratory of Radiation Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
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Retention of the in vitro radiosensitizing potential of gemcitabine under anoxic conditions, in p53 wild-type and p53-deficient non-small-cell lung carcinoma cells. Int J Radiat Oncol Biol Phys 2011; 80:558-66. [PMID: 21377279 DOI: 10.1016/j.ijrobp.2010.12.051] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 12/08/2010] [Accepted: 12/17/2010] [Indexed: 11/23/2022]
Abstract
PURPOSE Whereas radiosensitization by gemcitabine is well studied under normal oxygen conditions, little is known about its radiosensitizing potential under reduced oxygen conditions. Therefore, the present study evaluated the impact of anoxia on gemcitabine-mediated radiosensitization. METHODS AND MATERIALS The clonogenic assay was performed in three isogenic A549 cell lines differing in p53 status (24 h, 0-15 nM gemcitabine, 0-8 Gy irradiation, normoxia vs. anoxia). Using radiosensitizing conditions, cells were collected for cell cycle analysis and apoptosis detection. RESULTS Whereas wild-type p53 A549-LXSN cells were more sensitive to radiation than p53-deficient A549-E6 cells, both cell lines showed similar radiosensitization by gemcitabine under normoxia and anoxia. Independent of p53 functionality, gemcitabine was able to overcome anoxia-induced G(0/1) arrest and established an (early) S phase block in normoxic and anoxic cells. The percentage early and late apoptotic/necrotic cells increased with the gemcitabine/radiation combination, with a significant difference between A549-LXSN and A549-E6. CONCLUSIONS This study is the first to show that gemcitabine retains its radiosensitizing potential under low oxygen conditions. Although radiosensitization was observed in both p53 wild-type and p53-deficient cells, p53 status might influence induction of apoptosis after gemcitabine/radiation treatment, whereas no effect on cell cycle progression was noticed.
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Difluorodeoxyuridine plasma concentrations after low-dose gemcitabine during chemoradiation in head and neck cancer patients. Cancer Chemother Pharmacol 2010; 68:185-91. [PMID: 20882386 DOI: 10.1007/s00280-010-1471-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 09/13/2010] [Indexed: 12/21/2022]
Abstract
PURPOSE The aim of this study was to investigate whether relevant plasma levels of dFdU could be detected during concurrent chemoradiation (CRT) with low doses of dFdC administered in patients with head and neck cancer and to assess the toxicity related to dose. METHODS dFdC was administered at doses of 5 mg/m² twice weekly or 10, 50, or 100 mg/m² weekly. Plasma concentrations of dFdU were determined daily for 7 days after the first administration and before each administration, thereafter. A high-performance liquid chromatographic method was used. During CRT, skin and mucosal toxicity were scored weekly according to the RTOG toxicity scoring system. RESULTS Eight patients were sampled at the 10-50 mg/m² dose and nine at the 5-100 mg/m² dose. dFdU levels were in the micromolar range, inducing RS in vitro. There was a strong correlation between the area under the curve of dFdU and the dose of dFdC (r = 0.803, P < 0.001) and a weak correlation between trough concentrations and total dose of dFdC (r = 0.408, P = 0.017). Duration of severe mucositis correlated with dFdC dose. CONCLUSIONS During CRT with 10-100 mg/m(2) of dFdC weekly or 5 mg/m(2) twice weekly, dFdU remains detectable at potentially radiosensitizing concentrations.
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Tsai MS, Kuo YH, Chiu YF, Su YC, Lin YW. Down-regulation of Rad51 expression overcomes drug resistance to gemcitabine in human non-small-cell lung cancer cells. J Pharmacol Exp Ther 2010; 335:830-40. [PMID: 20855443 DOI: 10.1124/jpet.110.173146] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Gemcitabine (2',2'-difluorodeoxycytidine), a deoxycytidine analog, and erlotinib, an epidermal growth factor receptor-tyrosine kinase inhibitor, are used clinically to treat patients with non-small-cell lung cancer (NSCLC). However, the molecular mechanisms for the drug resistance of gemcitabine in NSCLC cells are poorly understood. In this study, we used constructs containing human Rad51 cDNA or specific Rad51 small interfering RNA (siRNA) to examine the role of Rad51 in chemoresistance of gemcitabine in three different human NSCLC cell lines. Exposure of human NSCLC cell lines to gemcitabine increased the phosphorylation levels of mitogen-activated protein kinase kinase (MKK) 1/2-extracellular signal-regulated kinase (ERK) 1/2 and AKT in a time- and dose-dependent manner, which was accompanied by an induction of Rad51 mRNA and protein expression. Gemcitabine increased the expression of Rad51 by increasing its mRNA and protein stability. Blockage of ERK1/2 or AKT activation by 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U0126; MKK1/2 inhibitor) or 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002; phosphatidyl inositol 3-kinase inhibitor), respectively, decreased the gemcitabine-induced Rad51 expression. Gemcitabine-induced cytotoxicity was significantly increased using siRNA depletion of Rad51 or blockage of ERK1/2 and AKT activation. Erlotinib enhanced the gemcitabine-induced cytotoxicity via the inactivation of ERK1/2 and AKT and the down-regulation of Rad51. Enforced expression of constitutively active MKK1/2 or AKT recovered cell viability and Rad51 protein levels that were decreased by the combination of erlotinib and gemcitabine. Suppression of Rad51 expression or the inactivation of ERK1/2 or AKT signaling may be considered potential therapeutic modalities for gemcitabine-resistant lung cancer.
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Affiliation(s)
- Min-Shao Tsai
- Department of Biochemical Science and Technology, National Chiayi University, Chiayi 600, Taiwan
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Hastak K, Alli E, Ford JM. Synergistic chemosensitivity of triple-negative breast cancer cell lines to poly(ADP-Ribose) polymerase inhibition, gemcitabine, and cisplatin. Cancer Res 2010; 70:7970-80. [PMID: 20798217 DOI: 10.1158/0008-5472.can-09-4521] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The basal-like subtype of breast cancer is characterized by a triple-negative (TN) phenotype (estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2/neu negative). TN breast cancers share similar gene expression profiles and DNA repair deficiencies with BRCA1-associated breast cancers. BRCA1-mutant cells exhibit sensitivity to gemcitabine, cisplatin, and poly(ADP-ribose) polymerase (PARP) inhibition; therefore, we hypothesized that TN cancer cells may also exhibit sensitivity to these drugs. In this study, we report that TN breast cancer cells are more sensitive to these drugs compared with non-TN breast cancer cells. Moreover, combination treatments indicated that PARP inhibition by the small-molecule inhibitor PJ34 or siRNA knockdown synergized with gemcitabine and cisplatin in TN cells but not in luminal cancer cells. TN cells exhibited reduced repair of UV-induced cyclobutane pyrimidine dimers after PARP inhibition, suggesting that the synergistic effect of PJ34 and gemcitabine or cisplatin reflected inefficient nucleotide excision repair. Mechanistic investigations revealed that in TN cells, PJ34 reduced the levels of ΔNp63α with a concurrent increase in p73 and its downstream target p21. Thus, the sensitivity to combination treatment seemed to be mediated by sustained DNA damage and inefficient DNA repair triggering p63/p73-mediated apoptosis. Our results suggest a novel therapeutic strategy to treat women with TN breast cancer, an aggressive disease that presently lacks effective treatment options.
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Affiliation(s)
- Kedar Hastak
- Division of Oncology, Stanford University School of Medicine, Stanford, California, USA
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Wouters A, Pauwels B, Lardon F, Pattyn GGO, Lambrechts HAJ, Baay M, Meijnders P, Vermorken JB. In vitro study on the schedule-dependency of the interaction between pemetrexed, gemcitabine and irradiation in non-small cell lung cancer and head and neck cancer cells. BMC Cancer 2010; 10:441. [PMID: 20723210 PMCID: PMC2931492 DOI: 10.1186/1471-2407-10-441] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Accepted: 08/19/2010] [Indexed: 12/14/2022] Open
Abstract
Background Based on their different mechanisms of action, non-overlapping side effects and radiosensitising potential, combining the antimetabolites pemetrexed (multitargeted antifolate, MTA) and gemcitabine (2',2'-difluorodeoxycytidine, dFdC) with irradiation (RT) seems promising. This in vitro study, for the first time, presents the triple combination of MTA, dFdC and irradiation using various treatment schedules. Methods The cytotoxicity, radiosensitising potential and cell cycle effect of MTA were investigated in A549 (NSCLC) and CAL-27 (SCCHN) cells. Using simultaneous or sequential exposure schedules, the cytotoxicity and radiosensitising effect of 24 h MTA combined with 1 h or 24 h dFdC were analysed. Results Including a time interval between MTA exposure and irradiation seemed favourable to MTA immediately preceding or following radiotherapy. MTA induced a significant S phase accumulation that persisted for more than 8 h after drug removal. Among different MTA/dFdC combinations tested, the highest synergistic interaction was produced by 24 h MTA followed by 1 h dFdC. Combined with irradiation, this schedule showed a clear radiosensitising effect. Conclusions Results from our in vitro model suggest that the sequence 24 h MTA → 1 h dFdC → RT is the most rational design and would, after confirmation in an in vivo setting, possibly provide the greatest benefit in the clinic.
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Affiliation(s)
- An Wouters
- Laboratory of Cancer Research and Clinical Oncology, Department of Medical Oncology, University of Antwerp, 2610 Wilrijk, Belgium.
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Abstract
The prognosis for locally advanced pancreatic carcinoma remains dismal despite advances in chemotherapy and radiotherapy over the past few decades. The use of radiotherapy for pancreatic carcinoma is often disputed because of the hypothesis that patients with pancreatic cancer die from distant metastases. It is well accepted that the greatest chance for cure of pancreatic cancer involves surgical resection of the primary tumor. However, there is much controversy about the role of radiotherapy in local disease control. The aim of this Review is to discuss data from the available studies, both prospective and retrospective, that evaluate treatment options for locally advanced pancreatic cancer. We focus on the benefits associated with local therapies, including radiotherapy and surgical resection, as they relate to improved local disease control, prolonged overall survival and improved symptom control.
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Morgan MA, Parsels LA, Zhao L, Parsels JD, Davis MA, Hassan MC, Arumugarajah S, Hylander-Gans L, Morosini D, Simeone DM, Canman CE, Normolle DP, Zabludoff SD, Maybaum J, Lawrence TS. Mechanism of radiosensitization by the Chk1/2 inhibitor AZD7762 involves abrogation of the G2 checkpoint and inhibition of homologous recombinational DNA repair. Cancer Res 2010; 70:4972-81. [PMID: 20501833 DOI: 10.1158/0008-5472.can-09-3573] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The median survival for patients with locally advanced pancreatic cancer treated with gemcitabine and radiation is approximately 1 year. To develop improved treatment, we have combined a Chk1/2-targeted agent, AZD7762, currently in phase I clinical trials, with gemcitabine and ionizing radiation in preclinical pancreatic tumor models. We found that in vitro AZD7762 alone or in combination with gemcitabine significantly sensitized MiaPaCa-2 cells to radiation. AZD7762 inhibited Chk1 autophosphorylation (S296 Chk1), stabilized Cdc25A, and increased ATR/ATM-mediated Chk1 phosphorylation (S345 Chk1). Radiosensitization by AZD7762 was associated with abrogation of the G(2) checkpoint as well as with inhibition of Rad51 focus formation, inhibition of homologous recombination repair, and persistent gamma-H2AX expression. AZD7762 was also a radiation sensitizer in multiple tumor xenograft models. In both MiaPaCa-2- and patient-derived xenografts, AZD7762 significantly prolonged the median time required for tumor volume doubling in response to gemcitabine and radiation. Together, our findings suggest that G(2) checkpoint abrogation and homologous recombination repair inhibition both contribute to sensitization by Chk1 inhibition. Furthermore, they support the clinical use of AZD7762 in combination with gemcitabine and radiation for patients with locally advanced pancreatic cancer.
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Affiliation(s)
- Meredith A Morgan
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan 48109-5637, USA.
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Chemoradiotherapy for Inoperable Non-small Cell Lung Cancer. Lung Cancer 2010. [DOI: 10.1007/978-1-60761-524-8_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Background: The aim of this study was to evaluate the radiosensitising effect of gemcitabine, in terms of cell-cycle progression, induction of apoptosis, and to investigate the molecular events regulating apoptosis. Methods: Tumour cells were treated with gemcitabine, radiation, or the combination. 0–72 h after treatment, cells were collected for cell-cycle analysis and apoptosis determination. Caspase 8 and 9, Bid and tBid expression were determined by western blot. The mitochondrial membrane potential was determined using flow cytometry. An RT2Profiler PCR Array for human apoptotic genes was performed after the combination or TRAIL treatment. Results: Gemcitabine and radiation resulted in an early S-phase block immediately after treatment, after which the cells moved synchronously through the cell cycle. When cell-cycle distribution returned to pre-treatment levels, an increased induction of apoptosis was observed with activation of caspase 8 and 9 and a reduction of the mitochondrial membrane potential. Gene expression after treatment with radiosensitising conditions was comparable with expression after the TRAIL treatment. Conclusion: A role for the cell-cycle perturbations and the induction of apoptosis could be attributed to the radiosensitising effect of gemcitabine. Apoptosis induction was comparable with the apoptotic pathway observed after the TRAIL treatment, that is the involvement of the extrinsic apoptosis pathway.
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Danesi R, Altavilla G, Giovannetti E, Rosell R. Pharmacogenomics of gemcitabine in non-small-cell lung cancer and other solid tumors. Pharmacogenomics 2009; 10:69-80. [PMID: 19102717 DOI: 10.2217/14622416.10.1.69] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The validation of predictive biomarkers to tailor chemotherapy is a key issue in the development of effective treatment modalities against cancer. Examples of how genetics might affect drug response are offered by gemcitabine. A substantial number of potential biomarkers for sensitivity or resistance to gemcitabine have been proposed, including ribonucleotide reductase and cytidine deaminase polymorphisms, human equilibrative transporter-1 and ribonucleotide reductase gene-expression and AKT phosphorylation status. These markers displayed a significant relationship with disease response to the drug; however, their robustness needs to be evaluated within prospective studies. Moreover, recent trials of customized chemotherapy based on genetic markers have been carried out in non-small-cell lung cancer and promising pharmacogenetic determinants are gaining momentum, including BRCA1 and ERCC1. Hopefully, biomarkers to select patients most likely to respond to gemcitabine will be validated in the near future.
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Affiliation(s)
- Romano Danesi
- Division of Pharmacology & Chemotherapy, Department of Internal Medicine, University of Pisa, Via Roma 55, 56126 Pisa, Italy.
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Choudhury A, Zhao H, Jalali F, Al Rashid S, Ran J, Supiot S, Kiltie AE, Bristow RG. Targeting homologous recombination using imatinib results in enhanced tumor cell chemosensitivity and radiosensitivity. Mol Cancer Ther 2009; 8:203-13. [PMID: 19139130 DOI: 10.1158/1535-7163.mct-08-0959] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RAD51 is a key protein in the homologous recombination (HR) pathway of DNA double-strand break repair, and HR represents a novel target for cancer therapy. Because imatinib (Gleevec) has been reported to reduce RAD51 protein levels, we tested the clonogenic survival for RT112, H1299, PANC1, and PC3 tumor cell lines of varying p53 status and normal GM05757 normal fibroblasts after exposure to single agent imatinib (0-20 micromol/L; 0-72 hours). We also combined imatinib with DNA damaging agents that are toxic to RAD51-deficient cells, including ionizing radiation, gemcitabine, and mitomycin C. We observed decreased nuclear expression and chromatin binding of RAD51 protein following imatinib treatment. Imatinib also resulted in decreased error-free HR as determined by a flow cytometry-based integrated direct repeat-green fusion protein reporter system; this correlated to reduced RAD51 expression. Clonogenic survival experiments revealed increased cell kill for imatinib-treated cells in combination with ionizing radiation, gemcitabine, and mitomycin C, due in part to mitotic catastrophe. In experiments using imatinib and gemcitabine, tumor cell lines were sensitized to a greater extent than normal fibroblasts. This preservation of the therapeutic ratio was confirmed in vivo using PC3 xenograft growth delay and intestinal crypt cell clonogenic assays. HR inhibition may be an additional mechanism of action for the chemosensitization and radiosensitization of solid tumors with imatinib with preservation of the therapeutic ratio.
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Affiliation(s)
- Ananya Choudhury
- Department of Medical Biophysics, University of Toronto and Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario, Canada M5G2M9
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Jensen A, Debus J, Weber KJ. S-phase cell-specific modification by gemcitabine of PFGE-analyzed radiation-induced DNA fragmentation and rejoining. Int J Radiat Biol 2009; 84:770-7. [PMID: 18821391 DOI: 10.1080/09553000802317752] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE To assess the cell cycle-dependent influence of gemcitabine on ionizing radiation-induced DNA double-strand breakage (DSB) and rejoining measured by pulsed-field gel electrophoresis (PFGE). MATERIALS AND METHODS WIDR cells (human colon carcinoma) were synchronized by serum starvation/stimulation providing populations with 7% (G1) or 50% S-phase cells, respectively. Following drug treatment (0.5 microg/ml for 2 hours) cells were irradiated (up to 90 Gy) or incubated for repair (up to 6 h after 40 Gy). Cell cycle changes were monitored by flow cytometry, DNA fragmentation was assessed by PFGE as fraction of electrophoretically mobile DNA. RESULTS Without drug treatment, irradiated S-phase cells exhibited lower PFGE signals than the G1 cells due to the well known electrophoretic immobility of replicative DNA fragments, but DSB rejoining was not different. Gemcitabine pretreatment increased the apparent initial radiation-induced DNA fragmentation specifically for S-phase cells. This effect was rapidly reversed (1 h) during incubation for repair. CONCLUSIONS The data indicate that gemcitabine causes the formation of additional radiation-induced DSB in S-phase cells or destabilizes the replicative structures that otherwise prevent DNA fragment migration during PFGE. The latter would be rapidly restituted superimposing DSB rejoining. This is discussed in relation to the recently proposed role of mismatch repair in gemcitabine radiosensitization.
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Parsels LA, Morgan MA, Tanska DM, Parsels JD, Palmer BD, Booth RJ, Denny WA, Canman CE, Kraker AJ, Lawrence TS, Maybaum J. Gemcitabine sensitization by checkpoint kinase 1 inhibition correlates with inhibition of a Rad51 DNA damage response in pancreatic cancer cells. Mol Cancer Ther 2009; 8:45-54. [PMID: 19139112 PMCID: PMC2730564 DOI: 10.1158/1535-7163.mct-08-0662] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The protein kinase checkpoint kinase 1 (Chk1) has been implicated as a key regulator of cell cycle progression and DNA repair, and inhibitors of Chk1 (e.g., UCN-01 and EXEL-9844) potentiate the cytotoxic actions of chemotherapeutic drugs in tumor cells. We have examined the ability of PD-321852, a small-molecule Chk1 inhibitor, to potentiate gemcitabine-induced clonogenic death in a panel of pancreatic cancer cell lines and evaluated the relationship between endpoints associated with Chk1 inhibition and chemosensitization. Gemcitabine chemosensitization by minimally toxic concentrations of PD-321852 ranged from minimal (<3-fold change in survival) in Panc1 cells to >30-fold in MiaPaCa2 cells. PD-321852 inhibited Chk1 in all cell lines as evidenced by stabilization of Cdc25A; in combination with gemcitabine, a synergistic loss of Chk1 protein was observed in the more sensitized cell lines. Gemcitabine chemosensitization, however, did not correlate with abrogation of the S-M or G2-M checkpoint; PD-321852 did not induce premature mitotic entry in gemcitabine-treated BxPC3 or M-Panc96 cells, which were sensitized to gemcitabine 6.2- and 4.6-fold, respectively. In the more sensitized cells lines, PD-321852 not only inhibited gemcitabine-induced Rad51 focus formation and the recovery from gemcitabine-induced replication stress, as evidenced by persistence of gamma-H2AX, but also depleted these cells of Rad51 protein. Our data suggest the inhibition of this Chk1-mediated Rad51 response to gemcitabine-induced replication stress is an important factor in determining gemcitabine chemosensitization by Chk1 inhibition in pancreatic cancer cells.
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Affiliation(s)
- Leslie A. Parsels
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Meredith A. Morgan
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI
| | - Daria M. Tanska
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Joshua D. Parsels
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Brian D. Palmer
- Auckland Cancer Society Research Centre, School of Medical and Health Sciences, University of Auckland, NZ
| | | | - William A. Denny
- Auckland Cancer Society Research Centre, School of Medical and Health Sciences, University of Auckland, NZ
| | - Christine E. Canman
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | | | - Theodore S. Lawrence
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI
| | - Jonathan Maybaum
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
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Morgan MA, Parsels LA, Maybaum J, Lawrence TS. Improving gemcitabine-mediated radiosensitization using molecularly targeted therapy: a review. Clin Cancer Res 2008; 14:6744-50. [PMID: 18980967 DOI: 10.1158/1078-0432.ccr-08-1032] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the last three decades, gemcitabine has progressed from the status of a laboratory cytotoxic drug to a standard clinical chemotherapeutic agent and a potent radiation sensitizer. In an effort to improve the efficacy of gemcitabine, additional chemotherapeutic agents have been combined with gemcitabine (both with and without radiation) but with toxicity proving to be a major limitation. Therefore, the integration of molecularly targeted agents, which potentially produce less toxicity than standard chemotherapy, with gemcitabine radiation is a promising strategy for improving chemoradiation. Two of the most promising targets, described in this review, for improving the efficacy of gemcitabine radiation are epidermal growth factor receptor and checkpoint kinase 1.
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Affiliation(s)
- Meredith A Morgan
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-5637, USA.
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Ammons WS, Wang JW, Yang Z, Tidmarsh GF, Hoffman RM. A novel alkylating agent, glufosfamide, enhances the activity of gemcitabine in vitro and in vivo. Neoplasia 2007; 9:625-33. [PMID: 17786181 PMCID: PMC1950432 DOI: 10.1593/neo.07343] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 06/20/2007] [Accepted: 06/20/2007] [Indexed: 12/15/2022] Open
Abstract
Glufosfamide is an alkylating agent consisting of iphosphoramide mustard conjugated to glucose that is currently included in clinical studies of pancreatic cancer. We studied the effects of glufosfamide, in combination with gemcitabine, on in vitro and in vivo models of pancreatic cancer. In proliferation assays, glufosfamide and gemcitabine inhibited the growth of MiaPaCa-2, H766t, and PANC-1 cells, but the combination of the two agents provided greater effects. Apoptosis of MiaPaCa-2 cells, measured by fluorescence-activated cell sorting, was enhanced by the combination of the two drugs, compared to single-agent treatment. Glufosfamide alone inhibited the growth of red fluorescent protein-expressing MiaPaCa-2 tumors in an orthotopic nude mouse model in a dose-dependent manner. Combining glufosfamide (30 mg/kg) with gemcitabine resulted in enhanced inhibition of tumor growth and significantly prolonged survival. Immunohistochemistry of excised tumors revealed that both glufosfamide and gemcitabine increased levels of apoptosis (measured by terminal deoxynucleotidyl transferase-mediated nick end labeling staining) and reduced proliferation (measured by proliferating cell nuclear antigen staining). No effects on microvessel density were observed. These results support the use of the alkylating agent glufosfamide and the DNA synthesis inhibitor gemcitabine, rather than the use of either agent alone, to provide greater benefits and demonstrate that this combination treatment should be useful in the clinical treatment of pancreatic carcinoma.
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Affiliation(s)
- W Steve Ammons
- Department of Pharmacology and Toxicology, Threshold Pharmaceuticals, Inc., Redwood City, CA 94061, USA.
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Abstract
Radiosensitization with antimetabolites has improved clinical outcome for patients with solid malignancies, especially cancers of the GI tract, cervix, and head and neck. Fluorouracil (FU) and hydroxyurea have been widely used clinically during the last four decades, and promising results have been observed more recently with gemcitabine. Although the antimetabolites all target DNA replication, they differ with respect to the mechanisms by which they produce radiosensitization. The antimetabolite radiosensitizers may inhibit thymidylate synthase (TS) or ribonucleotide reductase, and the nucleoside/nucleobase analogs can be incorporated into DNA. Radiosensitization can result from chemotherapy-induced increase in DNA double-strand breaks or inhibition of their repair. Studies of repair pathways involved in radiosensitization with antimetabolites implicate base excision repair with the TS inhibitors, homologous recombination with gemcitabine, and mismatch repair with FU and gemcitabine. Gemcitabine can also stimulate epidermal growth factor receptor (EGFR) phosphorylation; inhibiting this effect with EGFR inhibitors can potentiate cytotoxicity and radiosensitization. Additional work is necessary to determine more precisely the processes by which antimetabolites act as radiation sensitizers and to define the optimal sequencing of these agents with EGFR inhibitors to provide better guidance for clinical protocols combining these drugs with radiotherapy.
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Affiliation(s)
- Donna S Shewach
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, MI 48109-0504, USA.
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Flanagan SA, Robinson BW, Krokosky CM, Shewach DS. Mismatched nucleotides as the lesions responsible for radiosensitization with gemcitabine: a new paradigm for antimetabolite radiosensitizers. Mol Cancer Ther 2007; 6:1858-68. [PMID: 17575114 DOI: 10.1158/1535-7163.mct-07-0068] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Radiation sensitization by 2',2'-difluoro-2'-deoxycytidine (dFdCyd) has correlated with dATP depletion [dFdCDP-mediated inhibition of ribonucleotide reductase (RR)] and S-phase accumulation. We hypothesized that radiosensitization by dFdCyd is due to nucleotide misincorporations in the presence of deoxynucleotide triphosphate pool imbalances, which, if not repaired, augments cell death following irradiation. The ability of dFdCyd to produce misincorporations was measured as pSP189 plasmid mutations in hMLH1-deficient [mismatch repair (MMR) deficient] and hMLH1-expressing (MMR proficient) HCT116 cells. Only MMR-deficient cells showed a significant increase in nucleotide misincorporations (2- to 3-fold increase; P <or= 0.01) after radiosensitizing concentrations of dFdCyd +/- 5 Gy radiation, which persisted for at least 96 h. dFdCyd (10 nmol/L) did not radiosensitize MMR-proficient HCT116 or A549 cells, but following small interfering RNA-mediated suppression of hMLH1, this concentration produced excellent radiosensitization (radiation enhancement ratios = 1.6 +/- 0.1 and 1.5 +/- 0.1, respectively; P < 0.05) and a 2.5-fold increase in mutation frequency in A549 cells. Cytosine arabinoside (1-beta-d-arabinofuranosylcytosine), which can be incorporated into DNA but does not inhibit RR, failed to radiosensitize MMR-deficient cells or increase mutation frequency in the MMR-deficient and MMR-proficient cells. However, the RR inhibitor hydroxyurea radiosensitized MMR-deficient cells and increased nucleotide misincorporations (>or=5-fold increase; P < 0.05), thus further implicating the inhibition of RR as the mechanism underlying radiosensitization by dFdCyd. These data showed that the presence and persistence of mismatched nucleotides is integral to radiosensitization by dFdCyd and suggest a role for hMLH1 deficiency in eliciting the radiosensitizing effect.
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Affiliation(s)
- Sheryl A Flanagan
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0504, USA.
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Milenic DE, Garmestani K, Brady ED, Albert PS, Abdulla A, Flynn J, Brechbiel MW. Potentiation of high-LET radiation by gemcitabine: targeting HER2 with trastuzumab to treat disseminated peritoneal disease. Clin Cancer Res 2007; 13:1926-35. [PMID: 17363549 DOI: 10.1158/1078-0432.ccr-06-2300] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Recent studies from this laboratory with (212)Pb-trastuzumab have shown the feasibility of targeted therapy for the treatment of disseminated peritoneal disease using (212)Pb as an in vivo generator of (212)Bi. The objective of the studies presented here was improvement of the efficacy of alpha-particle radioimmunotherapy using a chemotherapeutic agent. EXPERIMENTAL DESIGN In a series of experiments, a treatment regimen was systematically developed in which athymic mice bearing i.p. LS-174T xenografts were injected i.p. with gemcitabine at 50 mg/kg followed by (212)Pb radioimmunotherapy. RESULTS In a pilot study, tumor-bearing mice were treated with gemcitabine and, 24 to 30 h later, with 5 or 10 muCi (212)Pb-trastuzumab. Improvement in median survival was observed at 5 microCi (212)Pb-trastuzumab in the absence (31 days) or presence (51 days) of gemcitabine: 45 and 70 days with 10 microCi versus 16 days for untreated mice (P < 0.001). Multiple doses of gemcitabine combined with a single (212)Pb radioimmunotherapy (10 microCi) administration was then evaluated. Mice received three doses of gemcitabine: one before (212)Pb-trastuzumab and two afterwards. Median survival of mice was 63 versus 54 days for those receiving a single gemcitabine dose before radioimmunotherapy (P < 0.001), specifically attributable to (212)Pb-trastuzumab (P = 0.01). Extending these findings, one versus two treatment cycles was compared. A cycle consisted of sequential treatment with gemcitabine, 10 microCi (212)Pb radioimmunotherapy, then one or two additional gemcitabine doses. In the first cycle, three doses of gemcitabine resulted in a median survival of 90 versus 21 days for the untreated mice. The greatest benefit was noted after cycle 2 in the mice receiving 10 microCi (212)Pb-trastuzumab and two doses of gemcitabine with a median survival of 196.5 days (P = 0.005). Pretreatment of tumor-bearing mice with two doses of gemcitabine before (212)Pb radioimmunotherapy was also assessed with gemcitabine injected 72 and 24 h before (212)Pb-trastuzumab. The median survival was 56 and 76 days with one and two doses of gemcitabine versus 49 days without gemcitabine. The effect may not be wholly specific to trastuzumab because (212)Pb-HuIgG with two doses of gemcitabine resulted in a median survival of 66 days (34 days without gemcitabine). CONCLUSIONS Treatment regimens combining chemotherapeutics with high-LET targeted therapy may have tremendous potential in the management and care of cancer patients.
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Affiliation(s)
- Diane E Milenic
- Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch and Biometric Research Branch, National Cancer Institute, Bethesda, MD 20892, USA.
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Supiot S, Thillays F, Rio E, Gouard S, Morgenstern A, Bruchertseifer F, Mahé MA, Chatal JF, Davodeau F, Chérel M. Gemcitabine radiosensitizes multiple myeloma cells to low let, but not high let, irradiation. Radiother Oncol 2007; 83:97-101. [PMID: 17383762 DOI: 10.1016/j.radonc.2007.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 11/14/2006] [Accepted: 02/09/2007] [Indexed: 11/23/2022]
Abstract
The radiosensitizing properties of gemcitabine in relation to low Linear Energy Transfer (LET) particles (Cobalt 60) and high-LET particles (alpha-RIT (213)Bi-radiolabeled CHX-DTPA-B-B4) were analyzed. Three multiple myeloma cell lines (LP1, RPMI 8226, U266) were irradiated with or without 10 nM gemcitabine 24 h prior to radiation. Gemcitabine led to radiosensitization of LP1 and U266 cells with low-LET (Radiation Enhancement Ratio: 1.55 and 1.49, respectively) but did not radiosensitize any cell line when combined with high-LET.
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Affiliation(s)
- Stéphane Supiot
- Département de Recherche en Cancérologie, Université de Nantes, Nantes, France
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