Brusatol Regulates Ferroptosis of Ovarian Cancer Through the Nrf2/HO-1/NQO1 and AKT/mTOR Double Signaling Pathways.

Introduction: Ovarian cancer (OC) is a common malignant tumor of the female reproductive system and is usually found at an advanced stage. However, the treatment of OC with conventional the efficacy of surgery and chemotherapy is limited. Brusatol (BRU) is a unique nuclear factor erythroid 2-related factor 2 (Nrf2) pathway inhibitor with significant anti-cancer effects. At the same time, the Nrf2 system also plays a vital role in ferroptosis, which can be used as a new way to treat tumors. This study investigated the mechanism of action of BRU as a novel ferroptosis inducer to inhibit OC cells.

Methods: Using bioinformatics to screen for key targets and pathways that act on OC in BRU, and then the effects of BRU on OC cells were examined by cell viability assay, clone formation assay, wound healing assay, and apoptosis assay. The intracellular levels of ROS (Reactive Oxygen Species), Fe2+, glutathione (GSH), and malondialdehyde (MDA) were also quantified. Western blotting analysis was then performed to verify ferroptosis marker proteins and pathways. In addition, the combination of Ferrostatin-1 (Fer-1) and BRU was further tested for ferroptosis-related markers.

Results: By obtaining BRU and OC targets, 171 potential BRU-OC action targets were screened to the core target NQO1. KEGG enrichment analysis showed that the anticancer effects of IBC were mediated through multiple pathways, including the PI3K-AKT and Ras signaling pathways. In vitro results showed that IBC inhibited the proliferation, invasion, and migration of OC cells and induced ferroptosis in OC cells.

Discussion: We demonstrated that BRU increased intracellular ROS, Fe2+, and MDA levels. It also significantly reduced intracellular GSH level and the expression of two marker proteins for ferroptosis, GPX4 and SLC7A11. Meanwhile, BRU could inhibit the Nrf2/HO-1/NQO1 and AKT/mTOR dual signaling pathways in OC cells. Furthermore, the combination of Ferrostatin-1 (Fer-1) and BRU reversed BRU-induced ferroptosis in OC cells.

Conclusion: In this study, we demonstrated for the first time through bioinformatics, molecular docking technology, and experimental validation that BRU acts as a novel inducer of ferroptosis in ovarian cancer cells by targeting the Nrf2/HO-1/NQO1 and AKT/mTOR dual signaling pathways, and may have great potential in the treatment of ovarian cancer cells.