The combination of nelfinavir and cisplatin drives lytic cell death through a caspase-8/caspase-3/GSDME axis in platinum-resistant ovarian cancer cells

Cisplatin (CDDP) is one of the most active chemotherapeutic agents used for ovarian cancer; however, primary or acquired platinum resistance is associated with poor prognosis. Nelfinavir (NFV), an HIV protease inhibitor, has demonstrated anti-tumor activity in multiple cancer models, but its interaction with CDDP in ovarian cancer has yet to be demonstrated. In this study, we investigated whether combined CDDP and NFV treatment provides a therapeutic advantage in platinum-resistant ovarian cancer cells. Drug synergy between NFV and CDDP was assessed using cell viability assays and Loewe additivity modelling. Apoptotic and pyroptotic signaling were evaluated by immunoblotting, mitochondrial membrane potential analysis, lactate dehydrogenase release, and caspase inhibition. Transcriptomic changes were assessed by bulk mRNA sequencing followed by differential gene expression analysis and gene set enrichment analysis. NFV synergized with CDDP to reduce the viability of platinum-resistant ovarian cancer cells and promoted a regulated lytic cell death phenotype involving apoptotic and pyroptotic features. Combination treatment induced caspase-8 and caspase-3 activation, with downstream gasdermin E (GSDME) processing. Inhibition of caspase-3 significantly attenuated cell death, while caspase-8 inhibition rescued viability and prevented Bid cleavage, caspase-3 activation, and GSDME cleavage. These effects occurred in the context of enhanced endoplasmic reticulum stress, increased DNA damage with reduced DNA repair, and impaired Akt-driven survival signaling. Together, these findings establish that NFV synergizes with CDDP in platinum-resistant ovarian cancer cells by promoting a caspase-8-dependent apoptotic-to-secondary pyroptotic response, supporting further investigation of NFV as a candidate drug for repurposing to enhance platinum-based therapy.