Min Xiaojia, Zhang Tingting, Lin Ying, Wang Bo, Zhu Kean
Hunan Provincial People's Hospital (The First Affiliated Hospital of Hunan Normal University), Changsha, China.
The Second Xiangya Hospital of Central South University, Changsha, China.
Biosci Rep. 2020 Sep 1. doi: 10.1042/BSR20200679.
Ovarian cancer is the most lethal diseases among women. The chemo-resistance has been a big challenge for the cancer treatment. It has been reported that metformin may inhibit ovarian cancer and is able to impede the development of drug resistance, but the molecular mechanisms remain elusive. In this study, we explored the molecular roles of metformin in Parkin expression and p53 ubiquitination in chemo-resistant ovarian cancer cells. Firstly, ovarian cancer and chemo-resistant ovarian cancer cells were selected for determining the expression of Parkin, p53, and p53 signaling pathway-related factors. Then the cell proliferation and viability after loss- and gain-of-function assays were measured. Besides, immunoprecipitation (IP) was used to determine the interactions between Parkin and p53, and the ubiquitination level of p53 was measured using in vitro ubiquitination assay. Finally, the degradation of p53 proteasome regulated by Parkin was monitored using the MG132 proteasome inhibitor. We found that metformin significantly inhibited the growth of ovarian cancer parental cells and chemo-resistant cells, and metformin promoted Parkin expression in chemo-resistant cells. Further, up-regulated Parkin expression promoted the ubiquitination and degradation of p53, and metformin inhibited the expression of p53 to suppress the proliferation of chemo-resistant ovarian cancer cells. Mechanistically, metformin could inhibit the growth of ovarian cancer cells by promoting the Parkin-induced p53 ubiquitination. Altogether, our study demonstrated an inhibitory role of metformin in the growth of chemo-resistant cancer cells through promoting the Parkin-induced p53 ubiquitination, which provides a novel mechanism of metformin for treating ovarian cancer.
卵巢癌是女性中最致命的疾病。化疗耐药一直是癌症治疗的一大挑战。据报道，二甲双胍可能抑制卵巢癌并能够阻碍耐药性的发展，但其分子机制仍不清楚。在本研究中，我们探讨了二甲双胍在化疗耐药卵巢癌细胞中对帕金蛋白（Parkin）表达和p53泛素化的分子作用。首先，选择卵巢癌和化疗耐药卵巢癌细胞来测定Parkin、p53以及p53信号通路相关因子的表达。然后在功能缺失和功能获得实验后测量细胞增殖和活力。此外，采用免疫沉淀法（IP）确定Parkin与p53之间的相互作用，并使用体外泛素化实验测量p53的泛素化水平。最后，使用MG132蛋白酶体抑制剂监测由Parkin调节的p53蛋白酶体降解情况。我们发现二甲双胍显著抑制卵巢癌亲本细胞和化疗耐药细胞的生长，并且二甲双胍促进化疗耐药细胞中Parkin的表达。此外，上调的Parkin表达促进p53的泛素化和降解，而二甲双胍抑制p53的表达以抑制化疗耐药卵巢癌细胞的增殖。机制上，二甲双胍可通过促进Parkin诱导的p53泛素化来抑制卵巢癌细胞的生长。总之，我们的研究证明了二甲双胍通过促进Parkin诱导的p53泛素化对化疗耐药癌细胞生长具有抑制作用，这为二甲双胍治疗卵巢癌提供了一种新机制。
