LncRNA-encoded peptide LRRC75A-AS1-ORF3 suppresses anti-tumor immunity in colorectal cancer through mitophagy-mediated attenuation of cGAS-STING signaling

Long non-coding RNAs (lncRNAs) serve as pivotal regulators of diverse physiological activities through their interactions with different biomolecules, and their aberrant expression frequently contributes to tumorigenesis and malignant progression. Emerging evidence has demonstrated that certain lncRNAs contain open reading frames that can generate useful short peptides, which influence cancer-related physiological and pathological pathways via diverse mechanisms. In this research, we identified that the lncRNA LRRC75A-AS1 encodes a conserved peptide consisting of 102 amino acids, designated as LRRC75A-AS1-ORF3. Notably, this peptide acts independently of the non-coding RNA itself to suppress anti-tumor immune responses and promote colorectal cancer progression. Mechanistically, LRRC75A-AS1-ORF3 is localized in the mitochondria, where it induces mitophagy, thereby eliminating cytosolic mitochondrial DNA (mtDNA) and downregulating the cGAS-STING signaling pathway. Our findings reveal a previously uncharacterized mechanism by which LRRC75A-AS1-ORF3 impairs anti-tumor immunity, thereby presenting a novel immunotherapeutic target for colorectal cancer treatment.