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.

中文翻译：

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二甲双胍通过促进 Parkin 诱导的 p53 泛素化来抑制卵巢癌细胞的生长。


卵巢癌是女性最致命的疾病。化疗耐药性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止耐药性的发展，但其分子机制仍不清楚。在这项研究中，我们探讨了二甲双胍在化疗耐药性卵巢癌细胞 Parkin 表达和 p53 泛素化中的分子作用。首先，选择卵巢癌和化疗耐药的卵巢癌细胞，测定Parkin、p53和p53信号通路相关因子的表达量。然后测量功能丧失和获得功能测定后的细胞增殖和活力。此外，免疫沉淀（IP）用于确定Parkin和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 Parkin 调节的 p53 蛋白酶体的降解。我们发现二甲双胍显着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，Parkin表达上调促进p53泛素化和降解，二甲双胍抑制p53表达从而抑制化疗耐药卵巢癌细胞的增殖。从机制上讲，二甲双胍可以通过促进 Parkin 诱导的 p53 泛素化来抑制卵巢癌细胞的生长。总之，我们的研究证明二甲双胍通过促进 Parkin 诱导的 p53 泛素化对化疗耐药癌细胞的生长具有抑制作用，这为二甲双胍治疗卵巢癌提供了新的机制。