Cell cycle checkpoints cooperate to suppress DNA and RNA associated molecular pattern recognition and anti-tumor immune responses

The DNA dependent pattern recognition receptor, cGAS mediates communication between genotoxic stress and the immune system. Mitotic chromosome missegregation is an established stimulator of cGAS activity, however, it is unclear if progression through mitosis is required for cancer cell intrinsic activation of immune mediated anti-tumor responses. Moreover, it is unknown if disruption of cell cycle checkpoints can restore responses in cancer cells that are recalcitrant to DNA damage induced inflammation. Here we demonstrate that prolonged cell cycle arrest at the G2-mitosis boundary from either CDK1 inhibition or excessive DNA damage prevents inflammatory stimulated gene expression and immune mediated destruction of tumors outside the field of irradiation. Remarkably, DNA damage induced inflammatory signaling is restored upon concomitant disruption of p53 and the G2 checkpoint, in a cGAS- and RIG-I- dependent manner. These findings link aberrant cell progression and p53 loss to an expanded spectrum of damage associated molecular pattern recognition and have implications for the design of rational approaches to augment anti-tumor immune responses. Overall design: Genome wide gene expression levels in MCF10A cell line and hTERT RPE-1 cell line were determined with RNA-Seq. The RNA-Seq experiments were divided into three different parts: (1) Cell cycle arrest or deficiency of cGAS/STING compromises irradiation induced inflammatory signaling in MCF10A cells; (2) Loss of p53 and G2-M checkpoint restores irradiation induced inflammatory signaling in c-NHEJ deficient MCF10A cells; (3) Loss of p53 and G2-M checkpoint activates cGAS independent inflammatory signaling in hTERT RPE-1 cells.