Discovery of pyroptosis-inducing natural products in neuroblastomas: computational studies with experimental validation.

Background: Neuroblastomas evade apoptosis due to oncogene mutations and antiapoptotic proteins, necessitating novel therapeutics that work in concert with other forms of cell death. Pyroptosis has potential as a strategic cell death mechanism in neuroblastoma. This study aimed to identify compounds that modulate pyroptosis, specifically those that target gasdermin D (GSDMD) oligomerization.

Methods: The study employed computational analysis and in vitro screening. The COCONUT database provides the natural compound dataset. Drug-likeness analysis and pharmacophore fitting were applied to screen potential GSDMD oligomerization modulators. Hit compounds underwent molecular docking with MOE and molecular dynamic (MD) simulations with NAMD 2.14 to analyse structural changes. The computational screening results were corroborated by in vitro assays, including the WST-8 assay, Western blot, and immunofluorescence, which target pyroptosis-specific caspase-1.

Results: Pharmacophore fitting, molecular docking, and molecular dynamics simulations identified the top five compounds, namely, quercetin, naringenin, hesperetin, curcumin, and galangin, as potent modulators of GSDMD oligomerization. Among these compounds, curcumin, quercetin, and galangin exerted potent cytotoxic effects on GSDMD-expressing neuroblastoma SK-N-AS cells, with IC₅₀ values of 21, 37, and 49 µM, respectively. Curcumin and quercetin also promoted apoptosis via increased caspase-3 cleavage and reduced procaspase-7 and -8 levels, as shown by immunoblotting. Curcumin and galangin upregulated caspase-1 expression, as demonstrated by the detection of a fluorescent-labelled inhibitor of caspase-1 by immunostaining, suggesting that these two compounds could induce pyroptosis. Hesperetin and naringenin showed low cytotoxicity, had no effect on caspase activation, and did not exhibit signs of pyroptosis in SK-NA-S cells.

Conclusions: Our study successfully identified curcumin as a strong regulator of both apoptosis and pyroptosis, quercetin as a strong modulator of apoptosis, and galangin as a strong modulator of pyroptosis. Further research on these compounds is crucial for the development of novel therapeutic strategies for neuroblastoma treatment.