It has been suggested that oxidative stress involving reactive oxygen species (ROS) induces granulosa cell apoptosis, leading to follicular atresia, and that T-lymphokine-activated killer cell-originated protein kinase (TOPK) suppresses cancer cell apoptosis induced by several stimuli. However, it remains to be determined whether TOPK affects oxidative stress-induced granulosa cell apoptosis. The present study demonstrates that TOPK inhibition increases human granulosa cOV434 cell apoptosis induced by hydrogen peroxide (H 2 O 2 ). co-treatment with the TOPK inhibitor, OTS514, in combination with H 2 O 2 increased p53 acetylation and its expression, whereas it decreased Sirtuin 1 (SIRT1) expression, contributing to the promotion of apoptosis. In addition, the SIRT1 activator, resveratrol, or the SIRT1 inhibitor, Ex527, reduced or elevated H 2 O 2 -induced cOV434 cell apoptosis, respectively. Furthermore, the p53 inhibitor, Pifithrin-μ, diminished the augmentation in poly(AdP-ribose) polymerase (PARP) cleavage induced by OTS514 plus H 2 O 2 , while the Mdm2 antagonist, Nutlin 3, increased PARP cleavage. Moreover, OTS514 further decreased the SIRT1 transcriptional activity decreased by H 2 O 2 , but promoted the H 2 O 2 -induced p53 or p21 transcriptional activity. Notably, the expression of exogenous p53 reduced SIRT1 transcriptional activity. Taken together, the findings of the present study demonstrate that TOPK inhibition promotes p53-mediated granulosa cell apoptosis through SIRT1 downregulation in response to H 2 O 2 . Therefore, it can be concluded that TOPK suppresses H 2 O 2 -induced apoptosis through the modulation of the p53/SIRT1 axis, suggesting a potential role of TOPK in the regulation of human granulosa cell apoptosis, leading to the promotion of abnormal follicular development.

Oxidative stress has been suggested to induce granulosa cell apoptosis, which contributes to follicular atresia. However, the mechanism via which oxidative stress mediates granulosa cell apoptosis remains elusive. Therefore, the aim of this study was to elucidate the molecular mechanisms regulating oxidative stress-induced granulosa cell apoptosis. The present study demonstrated that reactive oxygen species induced by H 2 O 2 resulted in human granulosa COV434 cell apoptosis via the regulation of sirtuin 1 (SIRT1)-mediated p53 activity. Endogenous SIRT1 expression was alleviated by H 2 O 2 treatment of COV434 cells in a time-dependent manner. In addition, knockdown or inhibition of SIRT1 promoted H 2 O 2 -induced poly(ADP-ribose) polymerase (PARP) cleavage and p53 acetylation, which led to an increase in COV434 cell apoptosis. Treatment with H 2 O 2 enhanced the expression levels of the p53-dependent proteins, p53-upregulated modulator of apoptosis (PUMA) and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), as well as those of p53; however, knockdown of p53 decreased cleaved PARP, PUMA and PMAIP1 expression levels induced by H 2 O 2 treatment. Moreover, knockdown of PUMA or PMAIP1 attenuated the H 2 O 2 induction of PARP cleavage and COV434 cell apoptosis. In conclusion, the present findings suggested that H 2 O 2 -induced oxidative stress causes granulosa COV434 cell apoptosis via the upregulation of p53 activity by SIRT1 suppression, indicating a mechanistic role of the SIRT1/p53 axis in H 2 O 2 -induced granulosa cell apoptosis.

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