MicroRNA-874-3p promotes testosterone-induced granulosa cell apoptosis by suppressing HDAC1-mediated p53 deacetylation

MicroRNA (miR)-874-3p is a newly identified miRNA that is involved in several pathological processes, including cancer, myocardial infarction, bone formation and erectile dysfunction. However, the role of miR-874-3p in polycystic ovary syndrome (PCOS) and granulosa cell (GC) apoptosis is not completely understood. The present study investigated the expression profile of miR-874-3p in PCOS by reverse transcription- quantitative PCR and the GC apoptosis by flow cytometry analysis. miR-874-3p expression was significantly upregulated in GCs isolated from patients with PCOS compared with patients without PCOS. In addition, miR-874-3p expression was positively correlated with GC apoptosis and testosterone levels in both patients with PCOS and patients without PCOS. Therefore, the present study also aimed to investigate the effects of miR-874-3p on testosterone-induced GC apoptosis. Compared with vehicle-treated GCs, miR-874-3p expression levels were significantly increased in testosterone-treated GCs, which was inhibited by the androgen receptor antagonist flutamide. GCs were transfected with either the miR-874-3p mimic or a miR-874-3p inhibitor. Compared with the control group, miR-874-3p mimic significantly enhanced GC apoptosis, whereas miR-874-3p inhibitor significantly decreased GC apoptosis. Moreover, histone deacetylase (HDAC) activity and HDAC1 expression levels were decreased in testosterone-treated GCs compared with vehicle-treated GCs. HDAC1 overexpression significantly attenuated the proapoptotic effects of testosterone. Additionally, miR-874-3p mimic and inhibitor significantly decreased and increased HDAC1 expression levels, respectively, compared with the control group. miR-874-3p inhibitor failed to attenuate HDAC1 overexpression-induced GC apoptosis. Furthermore, compared with the control group, testosterone treatment notably increased p53 expression and acetylation. Compared with the control group, western blotting analysis showed that miR-874-3p mimic notably increased p53 expression and acetylation, whereas miR-874-3p inhibitor markedly decreased p53 expression and acetylation. However, miR-874-3p inhibitor did not further decrease p53 acetylation and expression in cell overexpressing HDAC1. Collectively, the results of the present study indicated that miR-874-3p was upregulated in PCOS and promoted testosterone-induced GC apoptosis by suppressing HDAC1-mediated p53 deacetylation. Therefore, the present study improved the current understanding of the pathogenesis of PCOS and GC apoptosis.