The PARP-1 Inhibitor Olaparib Causes Retention of γ-H2AX Foci in <i>BRCA</i>1 Heterozygote Cells Following Exposure to Gamma Radiation
The PARP-1 Inhibitor Olaparib Causes Retention of γ-H2AX Foci in <i>BRCA</i>1 Heterozygote Cells Following Exposure to Gamma Radiation作者机构：Brunel Institute of Cancer Genetics and Pharmacogenomics Division of Biosciences School of Health Sciences and Social Care Brunel University Uxbridge UK Department of Radiotherapy St Bartholomew’s Hospital West Smithfield London UK
出 版 物：《Journal of Cancer Therapy》 (癌症治疗（英文）)
年 卷 期：2013年第4卷第11期
页 面：44-52页
学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学]
主 题：BRCA1 BRCA2 Heterozygote Radiosensitivity PARP Inhibitor Gamma-H2AX Imaging Flow Cytometry
摘 要：A novel treatment for cancer patients with homozygous deletions of BRCA1 and BRCA2 is to use drugs that inhibit the enzyme poly(ADP-ribose) polymerase (PARP). Specific inhibition of PARP-1 can induce synthetic lethality in irradiated cancer cells while theoretically leaving normal tissue unaffected. We recently demonstrated in a cell survival assay that lymphoblastoid cells with mono-allelic mutations of BRCA1 were hypersensitive to gamma radiation in the presence of the PARP-1 inhibitor Olaparib compared to normal cells and mono-allelic BRCA2 cells. To determine if the enhanced radiation sensitivity was due to a persistence of DNA strand breaks, we performed γ-H2AX foci analysis in cells derived from two normal individuals, three heterozygous BRCA1 and three heterozygous BRCA2 cell lines. Cells were exposed to 2 Gy gamma radiation in the presence or absence of 5 μM Olaparib. Using immunofluorescence and imaging flow cytometry, foci were measured in untreated cells and at 0.5, 3, 5 and 24 hours post-irradiation. In all lymphoblastoid cells treated with 2 Gy gamma radiation, there was a predictable induction of DNA strand breaks, with a modest but significant retention of foci over 24 hours in irradiated cells treated with Olaparib (ANOVA P 0.05). However, in mono-allelic BRCA1 cells, there was a failure to fully repair DNA double-strand breaks (DSB) in the presence of Olaparib, evidenced by a significant retention of foci at 24 hours’ post irradiation (t-Test P These data show that the cellular hypersensitivity of mono-allelic BRCA1 lymphoblastoid cells to gamma radiation in the presence of the Olaparib is due to the retention of DNA DSB. These data may indicate that patients with inherited mutations in the BRCA1 gene treated with radiotherapy and PARP-1 inhibitors may experience elevated radiation-associated normal tissue toxicity.
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