Abstract

The mechanism by which chemotherapy induces primary ovarian insufficiency (POI) remains unclear. This study aims to investigate the role of HMGCR in cisplatin-induced ovarian toxicity and its downstream molecular pathways. We established a cisplatin-induced POI mouse model. The protein levels were validated by immunohistochemistry (IHC), immunofluorescence (IF) and western blot (WB). Granulosa cell line KGN were used for in vitro experiments. RNA sequencing (RNA-seq) analyzed gene expression changes in mouse ovaries and KGN cells after HMGCR inhibition. Rescue experiments used exogenous cholesterol, and p53 agonist Nutlin-3a and inhibitor Pifithrin-α (PFT-α) for functional validation. Transcriptome analysis revealed that the cholesterol synthesis pathway was significantly suppressed in the ovaries of POI mice, with HMGCR-the rate-limiting enzyme in cholesterol biosynthesis-being markedly downregulated. Inhibition or knockdown of HMGCR in KGN cells led to increased ROS accumulation, elevated levels of lipid peroxidation (LPO), and enhanced apoptosis. Exogenous supplementation of cholesterol effectively mitigated these effects, confirming that cholesterol deficiency is the causative factor. Furthermore, RNA-seq analysis demonstrated that HMGCR suppression significantly activated the p53 signaling pathway, as evidenced by increased p53 phosphorylation, acetylation (K382), and upregulation of downstream pro-apoptotic targets p21 and PUMA. Pharmacological inhibition of p53 with PFT-α attenuated HMGCR inhibition-induced oxidative damage and apoptosis. In conclusion, cisplatin-induced ovarian injury is mediated through defects in cholesterol synthesis and subsequent p53 activation, identifying the HMGCR-cholesterol-p53 axis as a potential therapeutic target for POI.