The Role of the Hippo Signaling Pathway in 7,12-Dimethylbenz(a)anthracene (DMBA)-Induced Follicular Depletion

7,12-Dimethylbenz(a)anthracene (DMBA) is a polycyclic aromatic hydrocarbon formed by the combustion of organic substances and has ovotoxic and carcinogenic effects on ovarian follicular development in rodents. The Hippo signaling pathway contributes to the understanding of various molecular mechanisms, including cell proliferation, differentiation, apoptosis, organ size regulation, and tumorigenesis, as an evolutionarily conserved pathway. In this study, we hypothesized that the Hippo signaling pathway may play a role in the mechanism of DMBA-induced ovotoxicity. We aimed to identify Hippo signaling pathway proteins in DMBA-treated ovaries via immunohistochemistry and quantitative real-time PCR (qRT-PCR). Twenty-eight-day-old 18 BalbC female mice were used and divided into three groups. The control group received no treatment, the vehicle group was injected daily with sesame oil, and the DMBA group was injected intraperitoneally with 1 mg/kg/day DMBA (dissolved in sesame oil) for 14 consecutive days. The sections were subjected to periodic acid-Schiff (PAS) staining to demonstrate the morphological differences between the DMBA and control groups of mouse ovaries. Anti-Mullerian hormone (AMH) serum levels were analyzed via ELISA, and follicles were counted to evaluate the follicle reserve. Immunohistochemistry was performed to determine the localization of the Hippo signaling pathway proteins MST1/2, LATS1/2, YAP1, and TEAD4 and to assess oxidative stress with a nitrotyrosine (NTY) antibody. The mRNA levels of Hippo signaling components were detected via qRT-PCR. The Hippo signaling pathway may play a role in the mechanisms underlying the rapid depletion of follicles through increased oxidative stress, an increased number of atretic follicles, and a decreased number of corpus luteum in DMBA-induced ovotoxicity. We demonstrated that in the DMBA-induced ovotoxicity model, the Hippo signaling pathway is inactivated by YAP/TAZ translocation to the nucleus, and the increase in YAP1 and TEAD4 expression is at the translational level. This study provides the first evidence of the relationship between ovotoxicity and the Hippo signaling pathway in DMBA-induced ovotoxicity in mice. Therefore, our findings suggest that the Hippo pathway could be pharmacologically targeted to regulate DMBA-induced ovotoxicity.