miR-130b-3p is high-expressed in polycystic ovarian syndrome and promotes granulosa cell proliferation by targeting SMAD4.

ABSTRACT

BACKGROUND: Being one of the most prevalent metabolic and endocrine disorders, Polycystic Ovary Syndrome (PCOS) has been proven to be associated with microRNA-130b-3p (miR-130b-3p). However, the exact role played by miR-130b-3p in the pathogenesis and progression of PCOS remains unknown. Thus, this article is focused on elucidating the function of miR-130b-3p in the pathogenesis of PCOS. METHODS: The expression levels of miR-130b-3p and SMAD4 in tissues and cells responsible for the development of PCOS were determined by RT-qPCR and western blot. A miR-130b-3p mimic/inhibitor or si-SMAD4 were transfected into KGN cells. The cell viability was detected by CCK-8 and EDU methods. The activity of caspase-3 was measured by caspase-3 analysis. Subsequently, apoptosis and the cell cycle were measured via flow cytometry. The correlation between SMAD4 and miR-130b-3p was confirmed using an RNA pull-down assay and a dual luciferase reporter system assay. RESULTS: MiR-130b-3p was upregulated in the KGN cells and ovarian granulosa cells (GCs) of PCOS patients. It was found that miR-130b-3p overexpression or SMAD4 silencing can promote KGN cell proliferation and positive EDU rates, induce S phase arrest, inhibit apoptosis and caspase-3 activity. On the other hand, miR-130b-3p inhibitors reduce KGN cell proliferation, inhibit apoptosis and reverse the effect of si-SMAD4. CONCLUSION: MiR-130b-3p directly interacts with SMAD4 to induce KGN cell proliferation, inhibit apoptosis, suggesting that miR-130b-3p expression is positively correlated with the development of PCOS. This may serve as new evidence for the abnormal proliferation of GCs in PCOS.