Abstract

Background: NK cells are the core cells of the innate immune system, which can kill cancer cells non-specifically and almost do not cause immune rejection or neurotoxicity, thereby enabling broad application in immune cell therapy. The KLRG1/Cadherin signaling axis has been reported to inhibit the anti-tumor response of NK cells. However, the mechanism by which KLRG1 regulates CAR NK cell function remains unclear. Methods: To investigate the regulatory role of KLRG1 in CAR NK cell function, we constructed a KLRG1-knockdown NKG2D-CAR construct using gene-silencing techniques and transduced it into NK92 cells. Through in vitro and in vivo experiments, we examined the effects of KLRG1-interfered NKG2D-CAR NK cells on colorectal cancer. Results: Our findings suggest that KLRG1 knockdown enhanced the anti-colon cancer cytotoxicity of CAR NK cells by increasing the expression of CD69, CD107a, IFN-γ, GzmB, Perforin, and TNF-α both in vitro and in vivo. Additionally, KLRG1 deficiency improved the proliferation and survival of CAR NK cells while reducing their depletion. Mechanically, KLRG1 regulates CAR NK cell function through the ZAP-70/NF-κB signaling axis. Conclusion: Our study demonstrated that down-regulation of KLRG1 enhanced the anti-tumor activity of CAR NK cells, providing a new idea for CAR NK cell therapy.