Cancer cell DNA-sensing and apoptosis pathways

Cancer cell DNA-sensing and apoptosis pathways are critical intracellular surveillance systems that detect genomic instability and initiate programmed cell death or immune activation. The DNA-sensing component is primarily mediated by the Cyclic GMP-AMP synthase (cGAS) and the Stimulator of interferon genes (STING), which recognize double-stranded DNA in the cytoplasm—a common occurrence in cancer cells due to chromosomal instability or DNA damage (Li & Chen, 2018, Nature Reviews Immunology). Upon activation, this pathway induces the expression of type I interferons and other cytokines, promoting an inflamed tumor microenvironment that enhances anti-tumor immunity (Bakhoum & Cantley, 2018, Cancer Cell). Parallel to immune activation, these signals often converge on the intrinsic apoptosis pathway, where the balance of B-cell lymphoma 2 (BCL-2) family proteins determines whether the cell undergoes mitochondrial outer membrane permeabilization and subsequent death (Singh et al., 2019, Nature Reviews Molecular Cell Biology). Many tumors develop mechanisms to suppress these pathways, such as upregulating the DNA exonuclease Three-prime repair exonuclease 1 (TREX1) to clear cytosolic DNA or overexpressing anti-apoptotic proteins like BCL-2 to evade cell death. Therapeutic strategies currently under investigation include STING agonists to boost immunotherapy efficacy and BCL-2 inhibitors, such as Venetoclax, to directly sensitize cancer cells to apoptosis (Mullard, 2018, Nature Reviews Drug Discovery). These pathways are also activated by conventional treatments like radiation and chemotherapy, which generate the cytosolic DNA fragments that trigger the sensing machinery.

Other names

cGAS-STING signaling pathwayCytosolic DNA sensing pathwayIntrinsic apoptotic pathwayMitochondrial apoptosis pathwayDNA damage-induced cell death

The mechanism involves the detection of cytosolic double-stranded DNA by Cyclic GMP-AMP synthase (cGAS), which catalyzes the production of cyclic GMP-AMP (cGAMP). cGAMP then binds to and activates the Stimulator of interferon genes (STING), leading to the recruitment of TBK1 and phosphorylation of IRF3, which induces type I interferon expression (Li & Chen, 2018, Nature Reviews Immunology). Simultaneously, DNA damage or cellular stress triggers the intrinsic apoptosis pathway by shifting the balance of BCL-2 family proteins toward pro-apoptotic members like BAX and BAK, resulting in mitochondrial outer membrane permeabilization and caspase activation (Singh et al., 2019, Nature Reviews Molecular Cell Biology).