Department of Oncology, The Second Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an, 710004, Shanxi, China.
Department of Surgical Oncology, The First Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
Breast Cancer Res Treat. 2019 Jul;176(1):109-117. doi: 10.1007/s10549-019-05189-w. Epub 2019 Apr 15.
Targeting DNA repair mechanisms to induce apoptosis may be a promising strategy for breast cancer treatment. Olaparib is proved to have anticancer effect by inhibiting DNA repairing protein poly (ADP-ribose) polymerase (PARP). However, the cytotoxicity of olaparib is very limited to homologous recombination-proficient cells. This study aims to examine the effect and mechanism of olaparib treatment in breast cancer cell lines.
We investigated the cytotoxic effect of various doses of olaparib treatment to MCF-7 and ZR-75-1 cells in vitro. mRNA and protein levels of PARP and APE1 were examined by real-time PCR and western blot, respectively. APE1-deficient cell lines were created by RNA interference and used for in vitro cytotoxicity study as well as in vivo study.
2 µM or higher concentrations of olaparib lead to significant cell death and ROS production. Moreover, olaparib treatment not only inhibits PARP1, but also reduces the expression of APE1 in both mRNA and protein levels. Deficiency of APE1 resulted in increased sensitivity of MCF-7 and ZR-75-1 cells to olaparib treatment. In vivo study showed that reduction of APE1 significantly reduced the volume and weight of MCF-7 xenografted tumors when treated with olaparib, which suggests the synergistic function of inhibition of APE1 in promoting antitumor effects of olaparib treatment.
To acquire better benefits for HR-proficient breast cancer patients, developing chemotherapeutic drugs antagonize APE1 would be an effective strategy to improve the clinical outcome of PARP inhibitors.
靶向 DNA 修复机制诱导细胞凋亡可能是治疗乳腺癌的一种有前途的策略。奥拉帕利通过抑制 DNA 修复蛋白聚（ADP-核糖）聚合酶（PARP）被证明具有抗癌作用。然而，奥拉帕利对同源重组有效的细胞的细胞毒性非常有限。本研究旨在研究奥拉帕利治疗乳腺癌细胞系的效果和机制。
我们研究了不同剂量的奥拉帕利处理 MCF-7 和 ZR-75-1 细胞的体外细胞毒性。通过实时 PCR 和 Western blot 分别检测 PARP 和 APE1 的 mRNA 和蛋白水平。通过 RNA 干扰创建 APE1 缺陷细胞系，并用于体外细胞毒性研究和体内研究。
2 µM 或更高浓度的奥拉帕利导致明显的细胞死亡和 ROS 产生。此外，奥拉帕利处理不仅抑制 PARP1，而且还降低了 APE1 在 mRNA 和蛋白水平的表达。APE1 缺陷导致 MCF-7 和 ZR-75-1 细胞对奥拉帕利处理的敏感性增加。体内研究表明，当用奥拉帕利治疗时，APE1 的减少显著减少了 MCF-7 异种移植瘤的体积和重量，这表明抑制 APE1 协同促进奥拉帕利治疗的抗肿瘤作用。
为了使 HR 阳性乳腺癌患者获得更好的受益，开发拮抗 APE1 的化疗药物将是提高 PARP 抑制剂临床疗效的有效策略。
