Antitumor activity of a Schiff base copper(II) complex against triple-negative breast cancer via ferroptosis and autophagy pathways.

Triple-negative breast cancer (TNBC) is an aggressive subtype lacking effective therapeutic targets and exhibiting poor response to conventional chemotherapy. Copper(II) complexes have emerged as promising anti-TNBC agents due to their multi-targeting antitumor activity. Here, we report that a Schiff base copper(II) complex, [Cu(o-van-gly)(bipy)]·MeOH (YH), potently inhibits proliferation and migration of TNBC cells and induces apoptosis. Mechanistically, YH treatment increases reactive oxygen species (ROS) and intracellular iron levels, downregulates GPX4 and SLC7A11, indicating activation of ferroptosis. YH also elevates the LC3-II/LC3-I ratio and Beclin-1 expression, while reducing p62, demonstrating induction of autophagy. Notably, Fer-1 and 3-MA each significantly rescue YH-induced cell death, confirming the functional requirement of both pathways in YH's cytotoxicity. Furthermore, inhibition of autophagy partially attenuates ferroptosis markers, suggesting that autophagy acts upstream to promote ferroptosis in this context. In vivo, using a syngeneic 4 T1-Luc mouse model, YH markedly suppresses tumor growth, with no obvious histopathological changes in the liver observed. Histological and immunohistochemical analyses confirm increased necrosis, apoptosis, and the same pathway alterations as observed in vitro. Collectively, YH exerts potent anti-TNBC activity by concurrently activating ferroptosis and autophagy, with autophagy functioning as a pro-ferroptotic mechanism. This study provides a dual-pathway targeting strategy and supports YH as a lead candidate for TNBC therapy.