A synthetic lethal screen identifies the Vitamin D receptor as a novel gemcitabine sensitizer in pancreatic cancer cells
A synthetic lethal screen identifies the Vitamin D receptor as a novel gemcitabine sensitizer in pancreatic cancer cells
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DOI：
10.4161/15384101.2014.967070
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发表时间：
2014-12-15
期刊：
影响因子：
4.3
通讯作者：
Yen, T. J.
中科院分区：
文献类型：
--
作者：
Bhattacharjee, V.;Zhou, Y.;Yen, T. J.
克服胰腺癌(PCA)细胞的化疗耐药将显著延长患者的生存时间。目前的治疗方式依赖于各种DNA损伤剂，包括吉西他滨、FOLFIRINOX和阿布拉克生，它们激活细胞周期检查点，使细胞能够在这些药物治疗中存活。事实上，这些治疗方案只将患者的生存时间延长了几个月。PCa肿瘤复杂的微环境使药物输送变得复杂，从而降低了PCa肿瘤对化疗的敏感性。在这项研究中，一个全基因组的siRNA文库被用来对用吉西他滨处理的Panc1细胞进行人工致死筛选。该药物的亚致死剂量(50纳米)被用来模拟体内对前列腺癌肿瘤的药物可获得性限制的情况。从筛查中鉴定出27个有效的致敏基因，包括维生素D受体(VDR)。克隆生存分析显示吉西他滨在多种PCa细胞系中的敏感性依赖于VDR。敏感化不是通过超越检查站实现的，而是通过扰乱DNA修复实现的。VDR基因敲除破坏了细胞对吉西他滨治疗的反应，形成磷酸-H_2AX和RAD51焦点的能力。破坏RAD51病灶的形成，这损害了同源重组，这与PCa细胞对PARP抑制剂Rucaparib的敏感性增加一致。因此，抑制PCa细胞中的VDR为提高遗传毒性药物的疗效提供了一条新的途径。
Overcoming chemoresistance of pancreatic cancer (PCa) cells should significantly extend patient survival. The current treatment modalities rely on a variety of DNA damaging agents including gemcitabine, FOLFIRINOX, and Abraxane that activate cell cycle checkpoints, which allows cells to survive these drug treaments. Indeed, these treatment regimens have only extended patient survival by a few months. The complex microenvironment of PCa tumors has been shown to complicate drug delivery thus decreasing the sensitivity of PCa tumors to chemotherapy. In this study, a genome-wide siRNA library was used to conduct a synthetic lethal screen of Panc1 cells that was treated with gemcitabine. A sublethal dose (50nM) of the drug was used to model situations of limiting drug availability to PCa tumors in vivo. Twenty-seven validated sensitizer genes were identified from the screen including the Vitamin D receptor (VDR). Gemcitabine sensitivity was shown to be VDR dependent in multiple PCa cell lines in clonogenic survival assays. Sensitization was not achieved through checkpoint override but rather through disrupting DNA repair. VDR knockdown disrupted the cells' ability to form phospho-H2AX and Rad51 foci in response to gemcitabine treatment. Disruption of Rad51 foci formation, which compromises homologous recombination, was consistent with increased sensitivity of PCa cells to the PARP inhibitor Rucaparib. Thus inhibition of VDR in PCa cells provides a new way to enhance the efficacy of genotoxic drugs.