Impact of HLA-E gene polymorphism on HLA-E expression in tumor cells and prognosis in patients with stage III colorectal cancer.

Human leukocyte antigen (HLA)-E can contribute to the escape of cancer cells from host immune mechanisms. However, it is unknown whether HLA-E gene polymorphisms might play a role in cancer immune escape. This study aimed to evaluate the correlation between HLA-E gene polymorphisms and HLA-E expression in tumor tissue and determine the effects on clinical outcome of patients with stage III colorectal cancer. Two hundred thirty patients with stage III colorectal cancer were enrolled. HLA-E expression was detected in patient-derived tumor tissues with immunohistochemistry. HLA-E gene alleles in tumor tissues were detected with the polymerase chain reaction-sequence-specific primer method. In colorectal cancer tissue and in the normal tissue adjacent to the tumor, the HLA-E expression rates were 72.2 and 15.1 %, respectively (P < 0.05). Patients with overexpression, low expression, and no expression of HLA-E exhibited disease-free survival of 55.3, 72.9, and 72.1 %, respectively. Patients with HLA-E overexpression exhibited the lowest long-term survival rate. No relationship was observed between the type of HLA-E gene polymorphism and its expression level in tumor tissues; moreover, no polymorphisms appeared to affect the long-term survival of patients with colorectal cancer. The type of HLA-E polymorphism did not have an impact on HLA-E expression in tumors or the prognosis in patients with stage III colorectal cancer. However, the level of HLA-E expression in tumor tissue strongly predicted long-term survival in these patients.