Table_1_Bevacizumab increases the sensitivity of olaparib to homologous recombination-proficient ovarian cancer by suppressing CRY1 via PI3K/AKT pathway.xlsx

PARP inhibitors have changed the management of advanced high-grade epithelial ovarian cancer (EOC), especially homologous recombinant (HR)-deficient advanced high-grade EOC. However, the effect of PARP inhibitors on HR-proficient (HRP) EOC is limited. Thus, new therapeutic strategy for HRP EOC is desired. In recent clinical study, the combination of PARP inhibitors with anti-angiogenic agents improved therapeutic efficacy, even in HRP cases. These data suggested that anti-angiogenic agents might potentiate the response to PARP inhibitors in EOC cells. Here, we demonstrated that anti-angiogenic agents, bevacizumab and cediranib, increased the sensitivity of olaparib in HRP EOC cells by suppressing HR activity. Most of the γ-H2AX foci were co-localized with RAD51 foci in control cells. However, most of the RAD51 were decreased in the bevacizumab-treated cells. RNA sequencing showed that bevacizumab decreased the expression of CRY1 under DNA damage stress. CRY1 is one of the transcriptional coregulators associated with circadian rhythm and has recently been reported to regulate the expression of genes required for HR in cancer cells. We found that the anti-angiogenic agents suppressed the increase of CRY1 expression by inhibiting VEGF/VEGFR/PI3K pathway. The suppression of CRY1 expression resulted in decrease of HR activity. In addition, CRY1 inhibition also sensitized EOC cells to olaparib. These data suggested that anti-angiogenic agents and CRY1 inhibitors will be the promising candidate in the combination therapy with PARP inhibitors in HR-proficient EOC.

PARP抑制剂（PARP inhibitors）已改变了高级别上皮性卵巢癌（epithelial ovarian cancer, EOC）的临床管理策略，尤其针对同源重组（homologous recombinant, HR）缺陷型高级别EOC。然而，PARP抑制剂对同源重组功能正常型（HR-proficient, HRP）EOC的疗效十分有限，因此亟需开发针对HRP EOC的新型治疗方案。近期临床研究表明，PARP抑制剂与抗血管生成药物联合使用可提升治疗效果，即便在HRP病例中亦是如此。上述数据提示，抗血管生成药物或可增强EOC细胞对PARP抑制剂的应答反应。本研究证实，抗血管生成药物贝伐珠单抗（bevacizumab）与西地尼布（cediranib）可通过抑制HR活性，提升HRP EOC细胞对奥拉帕利（olaparib）的敏感性。对照组细胞中多数γ-H2AX焦点（γ-H2AX foci）与RAD51焦点（RAD51 foci）共定位，而经贝伐珠单抗处理的细胞中RAD51焦点数量显著减少。RNA测序（RNA sequencing）结果显示，贝伐珠单抗可在DNA损伤应激条件下下调隐花色素1（CRY1）的表达。CRY1是一类与昼夜节律（circadian rhythm）相关的转录共调节因子，近期研究报道其可调控癌细胞中HR相关基因的表达。我们发现，抗血管生成药物可通过抑制VEGF/VEGFR/PI3K通路（VEGF/VEGFR/PI3K pathway），阻断DNA损伤应激下CRY1表达的上调。CRY1表达抑制会导致HR活性降低，此外，CRY1抑制同样可使EOC细胞对奥拉帕利产生敏感性。上述数据表明，抗血管生成药物与CRY1抑制剂有望成为PARP抑制剂联合治疗HRP EOC的潜在候选方案。