Etoposide Treatment of Cancer Cell Lines Results in Nuclear Localisation of Cleaved Gasdermin D

Objective: Overcoming resistance to apoptosis is one of the main goals of cancer treatment. Subversion of apoptosis to pyroptosis, an inflammatory cell death mediated by Gasdermin family members, was previously proposed as an alternative strategy for killing cancer cells. Since the pyroptotic activity of Gasdermin D has been mainly studied in the context of inflammasome activation and its association with cancer is mostly based on expression correlation, we sought to determine whether Gasdermin D-mediated pyroptosis could be triggered in response to drugs used to induce apoptosis in cancer cells. Materials and Methods: Cancer cells were treated with different concentrations of etoposide, gemcitabine, and cisplatin, which are used as chemotherapeutic agents in various ongoing clinical trials. Membrane integrity was evaluated by measuring lactate dehydrogenase release, and Gasdermin D and Caspase activations and subcellular localisation of Gasdermin D were determined by western blotting. Results: Upon treatment with the well-known apoptosis inducer etoposide, a necrotic form of programmed cell death was observed in different cancer cell lines even at low drug concentrations. Additionally, cleavage analysis revealed a 20-kDa-Gasdermin D fragment in the supernatant of treated cells. Surprisingly, this cleaved form was localised in the nuclei of etoposide-treated cells rather than in the well-defined cytosolic and plasma membrane localisations. Conclusion: Overall, these results demonstrate the complex interplay between different cell death pathways and suggest that Gasdermin D generates a fragment presenting an unknown function in the nuclei of etoposide-treated cancer cell lines.