Downregulation of CASC15 attenuates the symptoms of polycystic ovary syndrome by affecting granulosa cell proliferation and regulating ovarian follicular development

Polycystic ovary syndrome (PCOS) is a type of follicular dysplasia with an unclear pathogenesis, posing certain challenges in its diagnosis and treatment. Cancer susceptibility candidate 15 (CASC15), a long non-coding RNA closely associated with tumour development, has been implicated in PCOS onset and development. Therefore, this study aimed to investigate the molecular mechanisms underlying PCOS by downregulating CASC15 expression in both in vitro and in vivo models. We explored the potential regulatory relationship between CASC15 expression and PCOS by examining cell proliferation, cell cycle dynamics, cell autophagy, steroid hormone secretion capacity, and overall ovarian function in mice. We found that CASC15 expression in granulosa cells derived from patients with PCOS was significantly higher than those of the normal group (P < 0.001). In vitro experiments revealed that downregulating CASC15 significantly inhibited cell proliferation, promoted apoptosis, induced G1-phase cell cycle arrest, and influenced cellular autophagy levels. Moreover, downregulating CASC15 affected the follicular development process in newborn mouse ovaries. In vivo studies in mice demonstrated that disrupting CASC15 expression improved PCOS-related symptoms such as polycystic changes and hyperandrogenism, and significantly affected ovulation induction and embryo implantation in pregnant mice. Overall, CASC15 was highly expressed in granulosa cells of patients with PCOS and its downregulation improved PCOS-related symptoms by influencing granulosa cell function and follicular development in mice.