Penicilazaphilone C triggers ferroptosis in triple-negative breast cancer cells via the MDM2/p53/SLC7 A11/GPX4 pathway

Penicilazaphilone C (PAC) is a novel azaphilone isolated by our research team. While known for its antitumor properties, the potential of PAC to trigger ferroptosis in triple-negative breast cancer (TNBC) cells remains unexplored. This study aims to assess the ferroptotic induction capability of PAC and elucidate the underlying molecular mechanisms. Our results showed that treatment with PAC demonstrated a dose- and time-dependent inhibition of growth in MDA-MB-231 and MDA-MB-436 cells. Flow cytometry analysis and lactate dehydrogenase assay revealed various forms of cell death induced by PAC in both cell lines. Specifically, flow cytometry analyzed 7-AAD-stained dead cells, and ferroptosis markers, such as lipid peroxidation BODIPY-C11 and Fe²⁺ ions, identified ferroptosis as the major type of cell death pathway induced by PAC. Moreover, co-administration of the ferroptosis inhibitor Fer-1 notably mitigated PAC-induced cell death, further highlighting ferroptosis as the primary mechanism through which PAC inhibits TNBC cell growth and proliferation. Further exploration of the molecular mechanisms unveiled that PAC modulated the expression of Mouse double minute 2 (MDM2), p53, SLC7A11, and GPX4. In vivo experiments using nude mouse models implanted with MDA-MB-231 and MDA-MB-436 cells demonstrated that PAC treatment effectively suppressed tumor growth, increased levels of BODIPY-C11 and Fe²⁺ ions in isolated single tumor cells, downregulated MDM2 expression, and upregulated p53, SLC7A11, and GPX4 expression. These results suggest that PAC hinders TNBC cell growth and proliferation by modulating the MDM2/p53/SLC7A11/GPX4 axis to induce ferroptosis, positioning PAC as a promising azaphilone candidate for TNBC therapy.