TFAM downregulation promotes autophagy and ESCC survival through mtDNA stress-mediated STING pathway

Abstract

The dynamics of mitochondrial biogenesis regulation is critical in maintaining cellular homeostasis for immune regulation and tumor prevention. Here, we report that mitochondrial biogenesis disruption through TFAM reduction significantly impairs mitochondrial function, induces autophagy, and promotes esophageal squamous cell carcinoma (ESCC) growth. We found that TFAM protein reduction promotes mitochondrial DNA (mtDNA) release into the cytosol, induces cytosolic mtDNA stress, subsequently activates the cGAS-STING signaling pathway, thereby stimulating autophagy and ESCC growth. STING depletion or mtDNA degradation by DNase I abrogates mtDNA stress response, attenuates autophagy, and decreases the growth of TFAM depleted cells. In addition, autophagy inhibitor also ameliorates mitochondrial dysfunction-induced activation of the cGAS-STING signaling pathway and ESCC growth. In conclusion, our results indicate that mtDNA stress induced by mitochondria biogenesis perturbation activates the cGAS-STING pathway and autophagy to promote ESCC growth, revealing an underappreciated therapeutic strategy for ESCC.