Expressions and clinical significance of PD-1 and PD-L1 in colon cancer

Abstract

Objective To investigate the expressions of PD-1 and PD-L1 in colon cancer tissue and their relationship with clinicopathological features and prognosis, and to provide some references for the treatment of colon cancer. Methods The expressions of PD-1 and PD-L1 proteins and mRNA in resected colon cancer tissues and adjacent normal tissues collected from our hospital between June, 2011 and June, 2013 were detected by immunohistochemistry and real-time fluorescence quantitative PCR. The relationship between the expressions of PD-1 and PD-L1 proteins on one hand and clinicopathological characteristics on the other hand was analyzed. The relationship between the expressions of PD-1 and PD-L1 proteins on one hand and the prognosis of colon cancer on the other hand was analyzed. Results The positive expression rates of PD-1 and PD-L1 proteins in the colon cancer tissues were significantly higher than those in the adjacent tissues (both P 3cm, TNM stage Ⅲ-Ⅳ, and Ducks stage C-D were significantly higher than those in the tumors with diameter < 3 cm, TNM stage I-Ⅱ, and Ducks stage A-B (all P<0.05). The 5-year survival rates of the patients with positive and negative PD-1 expressions were 62.50% and 79.49%, respectively; the 5-year survival rate of the patients with positive PD-1 expressions was significantly lower than that of the patients with negative PD-1 expression (P<0.05). The 5-year survival rates of the patients with positive and negative PD-L1 expressions were 61.36% and 82.86%, respectively; the 5-year survival rate of the patients with positive PD-L1 were significantly lower than that of the patients with negative PD-L1 expression (P<0.05). Conclusion PD-1/PD-L1 pathway is an important mechanism of immunosuppression in colon cancer. Drug blockade of this pathway is beneficial to enhance the patients’ immune function, improve the therapeutic effect and prognosis. Key words: Colon cancer; Costimulatory molecules; PD-1; PD-L1