ABSTRACT
Objective:To investigate the relationship between expression of programmed cell death 1 ligand 2 (PD-L2) in colorectal cancer and prognosis, and explore the feasibility of application of PD-L2 in confocal laser endomicroscopy in the diagnosis of colorectal cancer. Methods:Immunohistochemistry was used to detect the expression of PD-L2 in 100 patients with colorectal cancer. The relationship between the expression levels and the prognosis of patients was analyzed. The expressions of PD-L2 in 30 cases of early colorectal cancer and adjacent normal mucosa were detected by immunohistochemistry and Western blotting. Confocal laser endomicroscopy was used to observe the difference in fluorescence intensity between early colorectal cancer and adjacent normal mucosa after being incubated with PD-L2 fluorescent antibody. Results:There were statistically significant differences in T-stage and distant metastasis between the patients with low and high expression of PD-L2, and they were both positively correlated with expression of PD-L2 (r=0.274, P=0.009; r=0.216, P=0.039). There was also a positive correlation between PD-L2 membrane expression and T stage (r=0.201, P=0.037). Survival analysis showed that the survival rate of patients with high PD-L2 expression was significantly lower than that of patients with low PD-L2 expression (P=0.000). The protein expression of PD-L2 in early colorectal cancer was significantly higher than that in adjacent normal mucosa. Under confocal laser endomicroscopy, the fluorescence intensity of early colorectal cancer was higher than that of adjacent normal mucosa. Conclusion:High expression of PD-L2 in colorectal cancer predicts poor prognosis in patients. Application of PD-L2 in confocal laser endomicroscopy may contribute to the diagnosis of colorectal cancer.