Indole-3-carbinol alleviates cisplatin-induced ovarian damage by inhibiting ovarian fibrosis through the TGF-β1/Smad pathway

Ovarian injury caused by chemotherapy severely threatens female reproductive health. Indole-3-carbinol (I3C), a natural substance that is abundant in cruciferous vegetables, has been reported to attenuate tissue damage. This study aimed to investigate whether I3C treatment could prevent ovarian damage induced by chemotherapy. A mouse ovarian injury model was established by the intraperitoneal injection of cisplatin into 8-week-old ICR mice (n = 18). The therapeutic effect of I3C was studied through ovarian index calculations, estrous cycle analysis and follicular reserve assessment. Additionally, we performed TUNEL (Terminal Deoxynucleotidyl Transferase-Mediated dUTP Nick End Labeling) and immunohistochemistry (IHC) staining to analyze the levels of apoptosis and fibrosis, respectively. A 3-week-old ICR mouse (n = 30) model was used for mechanistic exploration because the model can avoid the influence of the estrous cycle on gene expression and signaling pathways. Additionally, the human granulosa cell line KGN was treated with cisplatin and I3C in vitro to assess their effects on fibrotic markers and the transforming growth factor-beta (TGF-β)/Smad pathway. Western blotting (WB) and real-time quantitative polymerase chain reaction (RT-qPCR) were employed to assess the protein and mRNA levels, respectively. A tumor-bearing model established in 4-week-old female BALB/c nude mice (n = 24) was used to verify the anticancer activity of I3C in cervical cancer in vivo and that I3C protects against ovarian damage induced by chemotherapy. The administration of I3C restored the ovary index and decreased the incidence of estrous cycle disorders. The results of follicle counting revealed that I3C treatment inhibited primordial follicle overactivation caused by cisplatin treatment, and maintained the primordial follicle pool. We also found that I3C treatment decreased the level of apoptosis in ovaries. Additionally, I3C treatment reduced ovarian fibrosis and inhibited α-SMA and collagen I expression. Further research revealed that I3C treatment significantly downregulated the activity of the TGF-β1/Smad signaling pathway. In vitro experiments have shown that cisplatin induced fibrosis is regulated by the TGF-β1/Smad pathway. The results from a tumor-bearing model established in nude mice revealed that I3C exposure blocked cervical carcinoma growth, reduced ovarian fibrosis and maintained the primordial follicle reserve. In summary, I3C treatment alleviates cisplatin-induced primordial follicular overactivation, granulosa cell apoptosis and ovarian fibrosis, and promotes antitumor activity in vivo. Our study provides an innovative therapeutic strategy for preventing chemotherapy-mediated decreases in ovarian function in female cancer patients.