cGAS activation converges with intracellular acidification to promote STING aggregation and pyroptosis in tumor models

The cyclic GMP-AMP synthase (cGAS)/stimulator of IFN genes (STING) pathway is intimately associated with antitumoral immunity; however, the direct involvement of this pathway in tumor cell demise remains elusive. Here, we identified a compound, dodecyl 6-hydroxy-2-naphthoate (DHN), that induces pyroptosis in melanoma cells by activating noncanonical cGAS/STING signaling. DHN targets mitochondrial protein cyclophilin D (CypD) to induce the release of mitochondrial DNA, leading to cGAS activation and cyclic GMP-AMP (cGAMP) generation. Meanwhile, DHN-caused intracellular acidification induces protein kinase R-like endoplasmic reticulum kinase (PERK) activation, which promotes STING phosphorylation and polymerization in the presence of cGAMP, thereby facilitating the aggregation of STING in the ER, which serves as a platform to recruit Fas-associated via death domain (FADD) and caspase-8, leading to caspase-8 activation and subsequent gasdermin E cleavage, which ultimately results in pyroptosis of tumor cells and tumor regression in mouse models. The occurrence of this noncanonical cGAS/STING pathway-associated pyroptosis is also observed when both cGAS is activated and intracellular pH declines. Collectively, our findings reveal a pathway that links noncanonical cGAS/STING signaling to gasdermin E-mediated pyroptosis, thereby offering valuable insights for tumor therapy.