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QSAR and QSAAR modeling of nitroimidazole sulfonamide radiosensitizers: application of small dataset modeling. Struct Chem 2021. [DOI: 10.1007/s11224-021-01734-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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2-Nitroimidazoles induce mitochondrial stress and ferroptosis in glioma stem cells residing in a hypoxic niche. Commun Biol 2020; 3:450. [PMID: 32807853 PMCID: PMC7431527 DOI: 10.1038/s42003-020-01165-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 07/20/2020] [Indexed: 01/09/2023] Open
Abstract
Under hypoxic conditions, nitroimidazoles can replace oxygen as electron acceptors, thereby enhancing the effects of radiation on malignant cells. These compounds also accumulate in hypoxic cells, where they can act as cytotoxins or imaging agents. However, whether these effects apply to cancer stem cells has not been sufficiently explored. Here we show that the 2-nitroimidazole doranidazole potentiates radiation-induced DNA damage in hypoxic glioma stem cells (GSCs) and confers a significant survival benefit in mice harboring GSC-derived tumors in radiotherapy settings. Furthermore, doranidazole and misonidazole, but not metronidazole, manifested radiation-independent cytotoxicity for hypoxic GSCs that was mediated by ferroptosis induced partially through blockade of mitochondrial complexes I and II and resultant metabolic alterations in oxidative stress responses. Doranidazole also limited the growth of GSC-derived subcutaneous tumors and that of tumors in orthotopic brain slices. Our results thus reveal the theranostic potential of 2-nitroimidazoles as ferroptosis inducers that enable targeting GSCs in their hypoxic niche. Koike et al. show that the 2-nitroimidazole doranidazole increases radiation-induced DNA damage in hypoxic glioma stem cells (GSCs). They further demonstrate that additional radiation-independent cytotoxicity of 2-nitroimidazoles is due to ferroptosis that occurs through blockade of mitochondrial complexes I and II leading to metabolic changes in the oxidative stress response.
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Sharma A, Arambula JF, Koo S, Kumar R, Singh H, Sessler JL, Kim JS. Hypoxia-targeted drug delivery. Chem Soc Rev 2019; 48:771-813. [PMID: 30575832 PMCID: PMC6361706 DOI: 10.1039/c8cs00304a] [Citation(s) in RCA: 317] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hypoxia is a state of low oxygen tension found in numerous solid tumours. It is typically associated with abnormal vasculature, which results in a reduced supply of oxygen and nutrients, as well as impaired delivery of drugs. The hypoxic nature of tumours often leads to the development of localized heterogeneous environments characterized by variable oxygen concentrations, relatively low pH, and increased levels of reactive oxygen species (ROS). The hypoxic heterogeneity promotes tumour invasiveness, metastasis, angiogenesis, and an increase in multidrug-resistant proteins. These factors decrease the therapeutic efficacy of anticancer drugs and can provide a barrier to advancing drug leads beyond the early stages of preclinical development. This review highlights various hypoxia-targeted and activated design strategies for the formulation of drugs or prodrugs and their mechanism of action for tumour diagnosis and treatment.
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Affiliation(s)
- Amit Sharma
- Department of Chemistry, Korea University, Seoul, 02841, Korea.
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Yasui H, Kubota N, Nishizumi J, Sakai Y, Yamamori T, Inanami O. Preclinical study on hypoxic radiosensitizing effects of glycididazole in comparison with those of doranidazole in vitro and in vivo. Oncol Lett 2018; 15:1993-1998. [PMID: 29434899 DOI: 10.3892/ol.2017.7481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/20/2017] [Indexed: 11/06/2022] Open
Abstract
To overcome the radioresistance of hypoxic cells in solid tumor, numerous types of radiosensitizers specifically against them have been developed. Glycididazole has a chemical structure in which two metronidazole forms are combined, and is widely used as a hypoxic radiosensitizer in China. However, a detailed investigation of its radiosensitizing properties has not been performed. The present study reported a comparative assessment of glycididazole and doranidazole, another hypoxic radiosensitizer. All experiments were performed using the murine squamous cell carcinoma cell line SCCVII. Prior to X-irradiation, the cells were treated with the test drugs at concentrations of 10 mM and 200 mg/kg in vitro and in vivo, respectively. Uptake and their intratumor chemical forms were analyzed by high performance liquid chromatography (HPLC). Both drugs enhanced the reproductive cell death induced by X-irradiation under hypoxia. However, the growth delay assay of the transplanted tumor revealed the combination of X-irradiation and glycididazole showed a similar antitumor effect to that of X-irradiation alone, whereas doranidazole significantly sensitized the cells to X-irradiation. HPLC analysis revealed that incorporated glycididazole was decomposed to metronidazole and was therefore present at a lower concentration compared with that of doranidazole. The decomposition of glycididazole to metronidazole reduced its radiosensitizing efficiency in vivo. Elucidation of the kinetics of drugs containing metabolizable chemical forms is necessary for the optimization of clinical treatment.
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Affiliation(s)
- Hironobu Yasui
- Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Division of Veterinary Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan.,Central Institute of Isotope Science, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Nobuo Kubota
- R&D Laboratories, Pola Pharma Inc., Yokohama, Kanagawa 244-0812, Japan
| | - Junko Nishizumi
- R&D Laboratories, Pola Pharma Inc., Yokohama, Kanagawa 244-0812, Japan
| | - Yuri Sakai
- Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Division of Veterinary Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Tohru Yamamori
- Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Division of Veterinary Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Osamu Inanami
- Laboratory of Radiation Biology, Department of Applied Veterinary Sciences, Division of Veterinary Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
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Seshacharyulu P, Baine MJ, Souchek JJ, Menning M, Kaur S, Yan Y, Ouellette MM, Jain M, Lin C, Batra SK. Biological determinants of radioresistance and their remediation in pancreatic cancer. Biochim Biophys Acta Rev Cancer 2017; 1868:69-92. [PMID: 28249796 PMCID: PMC5548591 DOI: 10.1016/j.bbcan.2017.02.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/16/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Despite recent advances in radiotherapy, a majority of patients diagnosed with pancreatic cancer (PC) do not achieve objective responses due to the existence of intrinsic and acquired radioresistance. Identification of molecular mechanisms that compromise the efficacy of radiation therapy and targeting these pathways is paramount for improving radiation response in PC patients. In this review, we have summarized molecular mechanisms associated with the radio-resistant phenotype of PC. Briefly, we discuss the reversible and irreversible biological consequences of radiotherapy, such as DNA damage and DNA repair, mechanisms of cancer cell survival and radiation-induced apoptosis following radiotherapy. We further describe various small molecule inhibitors and molecular targeting agents currently being tested in preclinical and clinical studies as potential radiosensitizers for PC. Notably, we draw attention towards the confounding effects of cancer stem cells, immune system, and the tumor microenvironment in the context of PC radioresistance and radiosensitization. Finally, we discuss the need for examining selective radioprotectors in light of the emerging evidence on radiation toxicity to non-target tissue associated with PC radiotherapy.
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Affiliation(s)
- Parthasarathy Seshacharyulu
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Michael J Baine
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Joshua J Souchek
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Melanie Menning
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sukhwinder Kaur
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Ying Yan
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Michel M. Ouellette
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Maneesh Jain
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Chi Lin
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Surinder K. Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
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Kempf H, Bleicher M, Meyer-Hermann M. Spatio-Temporal Dynamics of Hypoxia during Radiotherapy. PLoS One 2015; 10:e0133357. [PMID: 26273841 PMCID: PMC4537194 DOI: 10.1371/journal.pone.0133357] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 06/26/2015] [Indexed: 12/27/2022] Open
Abstract
Tumour hypoxia plays a pivotal role in cancer therapy for most therapeutic approaches from radiotherapy to immunotherapy. The detailed and accurate knowledge of the oxygen distribution in a tumour is necessary in order to determine the right treatment strategy. Still, due to the limited spatial and temporal resolution of imaging methods as well as lacking fundamental understanding of internal oxygenation dynamics in tumours, the precise oxygen distribution map is rarely available for treatment planing. We employ an agent-based in silico tumour spheroid model in order to study the complex, localized and fast oxygen dynamics in tumour micro-regions which are induced by radiotherapy. A lattice-free, 3D, agent-based approach for cell representation is coupled with a high-resolution diffusion solver that includes a tissue density-dependent diffusion coefficient. This allows us to assess the space- and time-resolved reoxygenation response of a small subvolume of tumour tissue in response to radiotherapy. In response to irradiation the tumour nodule exhibits characteristic reoxygenation and re-depletion dynamics which we resolve with high spatio-temporal resolution. The reoxygenation follows specific timings, which should be respected in treatment in order to maximise the use of the oxygen enhancement effects. Oxygen dynamics within the tumour create windows of opportunity for the use of adjuvant chemotherapeutica and hypoxia-activated drugs. Overall, we show that by using modelling it is possible to follow the oxygenation dynamics beyond common resolution limits and predict beneficial strategies for therapy and in vitro verification. Models of cell cycle and oxygen dynamics in tumours should in the future be combined with imaging techniques, to allow for a systematic experimental study of possible improved schedules and to ultimately extend the reach of oxygenation monitoring available in clinical treatment.
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Affiliation(s)
- Harald Kempf
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt, Germany
| | - Marcus Bleicher
- Frankfurt Institute for Advanced Studies, Frankfurt, Germany
| | - Michael Meyer-Hermann
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
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Gold nanoparticle hyperthermia reduces radiotherapy dose. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1609-17. [PMID: 24990355 DOI: 10.1016/j.nano.2014.05.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 05/06/2014] [Accepted: 05/13/2014] [Indexed: 01/09/2023]
Abstract
UNLABELLED Gold nanoparticles can absorb near infrared light, resulting in heating and ablation of tumors. Gold nanoparticles have also been used for enhancing the X-ray dose to tumors. The combination of hyperthermia and radiotherapy is synergistic, importantly allowing a reduction in X-ray dose with improved therapeutic results. Here we intratumorally infused small 15 nm gold nanoparticles engineered to be transformed from infrared-transparent to infrared-absorptive by the tumor, then heated by infrared followed by X-ray treatment. Synergy was studied using a very radioresistant subcutaneous squamous cell carcinoma (SCCVII) in mice. It was found that the dose required to control 50% of the tumors, normally 55 Gy, could be reduced to <15 Gy (a factor of >3.7). Gold nanoparticles therefore provide a method to combine hyperthermia and radiotherapy to drastically reduce the X-ray radiation needed, thus sparing normal tissue, reducing side effects, and making radiotherapy more effective. FROM THE CLINICAL EDITOR Gold nanoparticles are known to enhance the efficacy of X-ray in tumor irradiation resulting in tumor heating and ablation. They also absorb near infrared light. This dual property was studied using a very radioresistant subcutaneous squamous cell carcinoma in mice, demonstrating that the dose required to control 50% of the tumors could be reduced by a factor of > 3.7, paving the way to potential future clinical applications.
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Yasui H, Asanuma T, Kino J, Yamamori T, Meike S, Nagane M, Kubota N, Kuwabara M, Inanami O. The prospective application of a hypoxic radiosensitizer, doranidazole to rat intracranial glioblastoma with blood brain barrier disruption. BMC Cancer 2013; 13:106. [PMID: 23496909 PMCID: PMC3599813 DOI: 10.1186/1471-2407-13-106] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 03/03/2013] [Indexed: 11/24/2022] Open
Abstract
Background Glioblastoma is one of the intractable cancers and is highly resistant to ionizing radiation. This radioresistance is partly due to the presence of a hypoxic region which is widely found in advanced malignant gliomas. In the present study, we evaluated the effectiveness of the hypoxic cell sensitizer doranidazole (PR-350) using the C6 rat glioblastoma model, focusing on the status of blood brain barrier (BBB). Methods Reproductive cell death in the rat C6 glioma cell line was determined by means of clonogenic assay. An intracranial C6 glioma model was established for the in vivo experiments. To investigate the status of the BBB in C6 glioma bearing brain, we performed the Evans blue extravasation test. Autoradiography with [14C]-doranidazole was performed to examine the distribution of doranidazole in the glioma tumor. T2-weighted MRI was employed to examine the effects of X-irradiation and/or doranidazole on tumor growth. Results Doranidazole significantly enhanced radiation-induced reproductive cell death in vitro under hypoxia, but not under normoxia. The BBB in C6-bearing brain was completely disrupted and [14C]-doranidazole specifically penetrated the tumor regions. Combined treatment with X-irradiation and doranidazole significantly inhibited the growth of C6 gliomas. Conclusions Our results revealed that BBB disruption in glioma enables BBB-impermeable radiosensitizers to penetrate and distribute in the target region. This study is the first to propose that in malignant glioma the administration of hydrophilic hypoxic radiosensitizers could be a potent strategy for improving the clinical outcome of radiotherapy without side effects.
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Affiliation(s)
- Hironobu Yasui
- Laboratory of Radiation Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18 Nishi 9, Kita-ku, Sapporo, Hokkaido, Japan
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Harada H. How can we overcome tumor hypoxia in radiation therapy? JOURNAL OF RADIATION RESEARCH 2011; 52:545-56. [PMID: 21952313 DOI: 10.1269/jrr.11056] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Local recurrence and distant metastasis frequently occur after radiation therapy for cancer and can be fatal. Evidence obtained from radiochemical and radiobiological studies has revealed these problems to be caused, at least in part, by a tumor-specific microenvironment, hypoxia. Moreover, a transcription factor, hypoxia-inducible factor 1 (HIF-1), was identified as pivotal to hypoxia-mediated radioresistance. To overcome the problems, radiation oncologists have recently obtained powerful tools, such as "simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT), which enables a booster dose of radiation to be delivered to small target fractions in a malignant tumor", "hypoxia-selective cytotoxins/drugs", and "HIF-1 inhibitors" etc. In order to fully exploit these innovative and interdisciplinary strategies in cancer therapy, it is critical to unveil the characteristics, intratumoral localization, and dynamics of hypoxia/HIF-1-active tumor cells during tumor growth and after radiation therapy. We have performed optical imaging experiments using tumor-bearing mice and revealed that the locations of HIF-1-active tumor cells changes dramatically as tumors grow. Moreover, HIF-1 activity changes markedly after radiation therapy. This review overviews 1) fundamental problems surrounding tumor hypoxia in current radiation therapy, 2) the function of HIF-1 in tumor radioresistance, 3) the dynamics of hypoxic tumor cells during tumor growth and after radiation therapy, and 4) how we should overcome the difficulties with radiation therapy using innovative interdisciplinary technologies.
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Affiliation(s)
- Hiroshi Harada
- Group of Radiation and Tumor Biology, Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Japan.
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Matsunaga A, Ueda Y, Yamada S, Harada Y, Shimada H, Hasegawa M, Tsujii H, Ochiai T, Yonemitsu Y. Carbon-ion beam treatment induces systemic antitumor immunity against murine squamous cell carcinoma. Cancer 2010; 116:3740-8. [PMID: 20564091 DOI: 10.1002/cncr.25134] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Carbon-ion beam (CIB) treatment is a powerful tool for controlling primary tumors in the clinical setting. However, to date, few clinical or experimental studies have investigated the effects of CIB treatment on tumor recurrence and antitumor immunity. METHODS A multiple challenge test was performed using syngenic and nude mouse models of a poorly immunogenic squamous cell carcinoma cell line (SCCVII) after CIB treatment at a clinically available dose (77 kiloelectron volts [keV]/microm) to primary tumors. To further examine changes in antitumor immunity in this model, the authors used dendritic cell (DC)-based immunotherapy. RESULTS In a syngenic model, CIB treatment itself resulted not only in efficient elimination of the primary tumor but also in a dramatic reduction of tumor formation after secondary tumor challenge at a contralateral site (P<.0001). Conversely, CIB treatment eliminated neither the primary nor the secondary tumor in nude mice. This antitumor effect produced by CIB treatment was enhanced significantly by combining it with DC immunotherapy (P=.0007). Combined CIB and DC treatment induced more intense cytolytic activity than CIB in a chromium-release assay. The third challenge tests, which included challenge with a third-party tumor cell line (FM3A) and effector depletion, revealed that the antitumor effects were the results of tumor-specific, long-lasting antitumor immunity through CD8-positive T lymphocytes. CONCLUSIONS To the authors' knowledge, this is the first demonstration of strong antitumor immunity induced by CIB treatment in a dermal tumor, and this effect was enhanced by combining it with DC-based immunotherapy. The authors concluded that this combination warrants further investigation as a promising modality for the prevention of tumor recurrence.
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Affiliation(s)
- Akinao Matsunaga
- Department of Gene Therapy, Chiba University Graduate School of Medicine, Chiba, Japan
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Hainfeld JF, Dilmanian FA, Zhong Z, Slatkin DN, Kalef-Ezra JA, Smilowitz HM. Gold nanoparticles enhance the radiation therapy of a murine squamous cell carcinoma. Phys Med Biol 2010; 55:3045-59. [DOI: 10.1088/0031-9155/55/11/004] [Citation(s) in RCA: 270] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Murata R, Tsujitani M, Horsman MR. Enhanced local tumour control after single or fractionated radiation treatment using the hypoxic cell radiosensitizer doranidazole. Radiother Oncol 2008; 87:331-8. [DOI: 10.1016/j.radonc.2008.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 03/04/2008] [Accepted: 03/05/2008] [Indexed: 11/27/2022]
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Lartigau E, Dewas S, Gras L. L’effet Oxygène, une cible ancienne toujours d’actualité ? Cancer Radiother 2008; 12:42-9. [DOI: 10.1016/j.canrad.2007.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 12/10/2007] [Accepted: 12/12/2007] [Indexed: 01/18/2023]
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Jin C, Bai L, Guo G. Radiosensitization by the combination of SR-2508 and paclitaxel in hypoxic human tumor cells in vitro. JOURNAL OF RADIATION RESEARCH 2007; 48:179-85. [PMID: 17420623 DOI: 10.1269/jrr.06105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The two radiosensitizers SR-2508 (etanidazole) and paclitaxel (taxol) have different dose-limiting toxicities in humans. Combination of the two radiosensitizers may increase radiosensitization without increasing toxicity. This study was carried out to determine the synergistic radiosensitizing effect of combination of SR-2508 and paclitaxel in two hypoxic human tumor cell lines: a breast carcinoma (MCF-7) and a carcinoma cervicis (HeLa). The 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay was used to determine the number of surviving cells. Cell cycle was evaluated by flow cytometry. Cell viability was measured by the ability of single cells to form colonies in vitro. Our data demonstrated that the radiosensitization produced by the two radiosensitizers was additive in hypoxic HeLa cells while held in the G(1) phase of the cell cycle. On the other hand, there was no synergistic radiosensitizing effect in hypoxic MCF-7 cells by combination of the two drugs. Our results suggested that the synergistic radiosensitizing effect of SR-2508 and paclitaxel may be tumor-dependent and that breast cancer may not be a good candidate. This study may provide a new combination of radiosensitizers in radiotherapy for cervical carcinoma.
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Affiliation(s)
- Cheng Jin
- Department of Radiation Medicine, Fourth Military Medical University, Xi'an, 710032 China
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