Targeting TREX1 induces innate immune response in drug resistant Small Cell Lung Cancer

Small cell lung cancer (SCLC) is the most lethal type of lung cancer. Paradoxically, this tumor displays an initial exquisite response to chemotherapy; however, at relapse, the tumor is highly resistant to subsequent available therapies. Here, we report that the expression of three prime repair exonuclease 1 (TREX1) is strongly induced in chemoresistant SCLCs. ATAC-seq and ChIP-seq revealed a significant increase in chromatin accessibility and transcriptional activity of TREX1 gene locus in chemoresistant SCLC. Analyses of human SCLC tumors and patient-derived xenografts (PDXs) also showed increase in TREX1 expression in post-chemotherapy samples. TREX1 depletion caused the activation of cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway due to cytoplasmic accumulation of damage-associated double-stranded DNA, inducing immunogenicity and enhancing the sensitivity of drug resistant cells to chemotherapy. These findings suggest TREX1 upregulation may partially contribute to the survival of resistant cells, and its inhibition may represent a promising therapeutic strategy to enhance antitumor immunity and potentiate the efficacy of chemotherapy and/or immunotherapy in chemoresistant SCLCs.