Objective To investigate the underlying mechanism of TRPM8 regulating the immune evasion of colon cancer cells. Methods The expression of TRPM8 in colon cancer cell line SW620 and human colon epithelial cell line CCD 841 CoN was detected by qRT-PCR and Western blot. SW620 cells were transfected with TRPM8 siRNA and pcDNA3.1-TRPM8，respectively，and the corresponding control groups（Control siRNA group and pcDNA3.1 group）were established. The CCK-8，colony formation experiment and flow cytometry were used to detect cell proliferation and apoptosis，microplate reader was used to detect Calcineurin activity，and Western blot was used to detect the expression of related proteins in Calcineurin-NFATc3 signaling pathway. The cell viability after co-incubation of CD8+ T cells and transfected SW620 cells was detected by CCK-8，and the expression of NFATc3 and PD-L1 proteins in SW620 cells treated with the Calcineurin inhibitor FK506 was detected by Western blot. Results The expressions of TRPM8 mRNA and protein in SW620 cells were up-regulated compared with CCD 841 CoN cells（P<0.01）. Compared with the Control siRNA group，the cell viability，cell proliferation，Calcineurin activity，and the expression of TRPM8，PD-L1 and NFATc3 proteins in SW620 cells after interference with TRPM8 expression decreased（P<0.01），while the cell apoptosis rate and p-NFATC3 protein expression increased（P<0.01）；overexpression of TRPM8 could enhance cell viability，cell proliferation and Calcineurin activity，up-regulate the expression of TRPM8，PD-L1 and NFATc3 proteins （P<0.01），and down-regulate the expression of p-NFATc3 proteins（P=0.002）. After CD8+ T cells co-incubation with SW620 cells that transfected with TRPM8 siRNA，the total cell viability decreased （P=0.002），but increased after CD8+ T cells co-incubation with SW620 cells transfected with pcDNA3.1-TRPM8（P=0.005）. FK506 could inhibit Calcineurin viability of SW620 cells and down-regulate the expression of NFATc3 and PD-L1 proteins（P<0.01）. Conclusion TRPM8 overexpression may promote the expression of PD-L1 by activating Calcineurin-NFATc3 signaling pathway，thereby enhancing the immune evasion ability of colon cancer cells and promoting its proliferation.
