Expression of miR-382-5p in polycystic ovary syndrome and its role in regulating granulosa cell function via targeting TOP1.

OBJECTIVES: The function of miR-382-5p in polycystic ovary syndrome (PCOS) remains unclear. This study aimed to investigate the potential regulatory mechanisms of the miR-382-5p/DNA topoisomerase I (TOP1) axis in PCOS. DESIGN: The study included 120 healthy controls and 120 PCOS patients. Serum samples were collected from all participants. Human granulosa-like cell line KGN was cultured in vitro and treated with insulin. METHODS: Reverse transcription quantitative PCR (RT-qPCR) was used to detect RNA expression; the Cell Counting Kit-8 (CCK-8) assay was used to assess cell proliferation; flow cytometry was used to detect cell apoptosis; and enzyme-linked immunosorbent assay (ELISA) was used to measure the protein levels of Bcl-2, Bax, and Cyclin D1. The protein content of TOP1 in KGN cells was detected by Western blotting. RNA immunoprecipitation (RIP) and dual-luciferase assays were used to validate the binding relationship. RESULTS: Serum miR-382-5p levels were significantly downregulated in PCOS patients, demonstrating good diagnostic value and showing a negative correlation with key clinical indicators of PCOS. In vitro experiments confirmed that, under insulin-induced conditions, overexpression of miR-382-5p significantly inhibited insulin-induced abnormal proliferation of granulosa cells, downregulated the protein of cyclin D1, and simultaneously promoted apoptosis by upregulating the pro-apoptotic protein Bax and downregulating the anti-apoptotic protein Bcl-2. This mechanism was associated with the direct targeting and inhibition of topoisomerase I (TOP1). In PCOS patients, elevated TOP1 mRNA and protein expression correlated negatively with miR-382-5p levels. Overexpression of TOP1 significantly reversed the antiproliferative and proapoptotic effects of miR-382-5p. LIMITATIONS: The verification of the miR 382 5p/TOP1 regulatory mechanism was limited to incomplete in vitro cell experiments and non-standard clinical detection, which cannot fully confirm its exact binding effect, in vivo cascade specificity, and independent pathogenic causality in PCOS patients. Additionally, all PCOS patients presented oligo-/anovulation, whereas healthy controls had regular menstrual cycles; given that circulating miR‑382‑5p levels vary with menstrual cycle phases, the observed downregulation in PCOS serum may partly stem from disrupted cyclic ovulation rather than representing an intrinsic PCOS-specific molecular alteration. Therefore, miR‑382‑5p should be interpreted as a correlative biomarker associated with PCOS phenotypes rather than an independent pathogenic mediator. CONCLUSIONS: miR-382-5p regulated the imbalance between insulin-mediated proliferation and apoptosis in KGN cells by directly targeting TOP1, thereby contributing to the progression of PCOS.