RAD51 Inhibitor Reverses Etoposide-Induced Genomic Toxicity and Instability in Esophageal Adenocarcinoma Cells.
RAD51 Inhibitor Reverses Etoposide-Induced Genomic Toxicity and Instability in Esophageal Adenocarcinoma Cells.
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DOI：
10.46439/toxicology.2.006
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Shammas MA
中科院分区：
文献类型：
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作者：
Liao C;Zhao J;Kumar S;Chakraborty C;Talluri S;Munshi NC;Shammas MA
在正常细胞中，同源重组（homologous recombination， HR）是严格调控的、精确的，它通过精确修复DNA损伤，在保持基因组完整性方面起着重要作用。RAD51是在DNA修复过程中介导同源碱基配对和链交换的重组酶。我们之前报道过，HR在食管腺癌（EAC）中自发升高（或失调），并导致持续的基因组变化和不稳定性。本研究的目的是评估RAD51抑制剂对化疗药物依托泊苷引起的基因组毒性的影响。研究了RAD51抑制剂和/或依托泊苷对EAC细胞株（FLO-1和OE19）细胞活力、凋亡和基因组完整性/稳定性的影响。基因组完整性/稳定性通过评估细胞γ-H2AX （DNA断裂的标志）、磷酸化RPA32 （DNA末端切除的标志，这是HR起始的一个独特步骤）和微核（基因组不稳定性的标志）来监测。在两种EAC细胞系中，用依托泊苷（一种化疗药物）治疗与显著的基因组毒性（从DNA断裂增加可见）和基因组不稳定性相关。一致地，治疗也与凋亡细胞死亡有关。在两种EAC细胞系中，RAD51的小分子抑制剂增加了细胞毒性，同时降低了依托泊苷引起的基因组毒性和不稳定性。RAD51抑制剂有可能增加细胞毒性，同时减少化疗对基因组的有害影响。
In normal cells, homologous recombination (HR) is strictly regulated and precise and plays an important role in preserving genomic integrity by accurately repairing DNA damage. RAD51 is the recombinase which mediates homologous base pairing and strand exchange during DNA repair by HR. We have previously reported that HR is spontaneously elevated (or dysregulated) in esophageal adenocarcinoma (EAC) and contributes to ongoing genomic changes and instability. The purpose of this study was to evaluate the impact of RAD51 inhibitor on genomic toxicity caused by etoposide, a chemotherapeutic agent. EAC cell lines (FLO-1 and OE19) were cultured in the presence of RAD51 inhibitor and/or etoposide, and impact on cell viability, apoptosis and genomic integrity/stability investigated. Genomic integrity/stability was monitored by evaluating cells for γ-H2AX (a marker for DNA breaks), phosphorylated RPA32 (a marker of DNA end resection which is a distinct step in the initiation of HR) and micronuclei (a marker of genomic instability). Treatment with etoposide, a chemotherapeutic agent, was associated with marked genomic toxicity (as evident from increase in DNA breaks) and genomic instability in both EAC cell lines. Consistently, the treatment was also associated with apoptotic cell death. A small molecule inhibitor of RAD51 increased cytotoxicity while reducing genomic toxicity and instability caused by etoposide, in both EAC cell lines. RAD51 inhibitors have potential to increase cytotoxicity while reducing harmful genomic impact of chemotherapy.