Molecular targeted therapies elicit concurrent apoptotic and GSDME-dependent pyroptotic tumor cell death

Purpose: The induced death signals following oncogene inhibition underlie clinical efficacy of molecular targeted therapies against human cancer, and defects of intact cell apoptosis machinery often lead to therapeutic failure. Despite potential importance, other forms of regulated cell death triggered by pharmacological intervention have not been systematically characterized. Experimental Design: Pyroptotic cell death was assessed by immunoblot, phase-contrast imaging, scanning electron microscopy, and flow cytometry. Tumor tissues of lung cancer patients were analyzed using immunohistochemistry. Functional impact of pyroptosis on drug response was investigated in cell lines and xenograft models. Results: We showed that diverse small molecule inhibitors specifically targeting KRAS-, EGFR- or ALK-driven lung cancer uniformly elicited robust pyroptotic cell death, in addition to simultaneously invoking cellular apoptosis. Upon drug treatment, the mitochondrial intrinsic apoptotic pathway was engaged and the mobilized caspase-3 protease cleaved and activated gasdermin E (GSDME, encoded by DFNA5), which permeabilized cytoplasmic membrane and executed cell-lytic pyroptosis. GSDME displayed ubiquitous expression in various lung cancer cell lines and clinical specimens, including KRAS-mutant, EGFR-altered and ALK-rearranged adenocarcinomas. As a result, co-occurrence and interplay of apoptosis and pyroptosis were widespread in lung cancer cells succumbing to genotype-matched regimens. We further demonstrated that pyroptotic cell death partially contributed to the drug response in a subset of cancer models. Conclusions: These results pinpoint GSDME-dependent pyroptosis as a previously unrecognized mechanism of action for molecular targeted agents to eradicate oncogene-addicted neoplastic cells, which may have important implications for the clinical development and optimal application of anti-cancer therapeutics.

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