Targeting G-quadruplex by TMPyP4 for inhibition of colorectal cancer through cell cycle arrest and boosting anti-tumor immunity.

G-quadruplex (G4) is a noncanonical DNA secondary structure known to induce DNA damage and regulate the expression of immune-related genes. We aim to exploit the G4 folding as a treatment strategy to trigger anti-tumor immune response. In this study, we observe that the abundant genomic G4 in epithelial cells coexists with increased infiltration of CD8⁺ T cells in colorectal cancer tissue. Furthermore, our data substantiate the inhibitory effect of the G4 ligand TMPyP4 on cancer progression while concurrently stimulating anti-tumor immunity. Mechanistically, TMPyP4 impedes cancer cell proliferation and induces G2/M cell cycle arrest. Additionally, in vivo experiments demonstrate that TMPyP4 enhances the anti-tumor immune response by triggering DNA damage and activating the cGAS-STING pathway, which fosters CD8⁺ T cell activation and dendritic cell maturation. Importantly, the combined treatment of TMPyP4 and anti-PD1 exhibits a synergistic therapeutic effect on colorectal cancer. In summary, our findings underscore the potential of the G4 ligand TMPyP4 as a dual strategy to target colorectal cancer: inhibiting cancer progression and augmenting anti-tumor immunity through the activation of cGAS-STING pathway.