PURPOSE: Polycystic ovary syndrome (PCOS) is currently recognized as a condition that affects several systems in the body, including the reproductive, endocrine, and cardiovascular systems. Prevalent among teenagers and women of reproductive age. Prior research has demonstrated an elevation of miR-34a-5p within the follicular fluid (FF) of women of PCOS. Despite this, the precise mechanisms through which miR-34a-5p influences granulosa cells (GC) development and function remain poorly characterized. METHODS: Therefore, this study investigates the involvement and pathogenic mechanisms of miR-34a-5p within GCs in the context of PCOS. The human granulosa-like tumor cell line (KGN) got transfected at a control, as well as a miR-34a-5p mimic and inhibitor, respectively. Monitor cellular proliferation in each experimental group. The experimental methods included RT-qPCR, CCK8, flow cytometry and western blotting. Also, the interaction between miR-34a-5p and the particular sequence of JAG1 has been verified using the dual luciferase assay. Further investigation of the connection involving miR-34a-5p and the Notch signaling pathway was conducted using bioinformatics analysis and experimental methods. RESULTS: The results demonstrated that miR-34a-5p expression was significantly elevated in the serum(p<
0. 0001)and FF (p = 0. 0402) of PCOS, whereas its expression in GCs (p = 0. 5522) showed no significant variation. Overexpressing miR-34a-5p caused a decrease in the rate at which KGN cells multiplied and an increase in programmed cell death. Conversely, inhibiting miR-34a-5p resulted in an increase in cell growth and a decrease in programmed cell death. Bioinformatics analysis and experimental results further demonstrated thatmiR-34a-5p interacts with the 3'UTR region of JAG1, leading to a negative regulation of the Jagged1-Notch signaling pathway. CONCLUSION: In summary, the miR-34a-5p molecule inhibits the growth of GCs as well as triggers programmed cell death by regulating the Jagged1-Notch signaling pathway. Silencing miR-34a-5p prevents dysfunction in GCs. Our analysis implies that miR-34a-5p is a new molecular site to treat PCOS.