Human leukocyte antigen (HLA)-E and HLA-F expression in gastric cancer

Human leukocyte antigen (HLA)-E and HLA-F are classified as non-classical HLA class Ib antigens. Ectopic HLA-E and HLA-F expression was recently detected in cancer cells; however, the clinical implication of their expression remains unknown. A total of 209 patients with gastric cancer were enrolled in this study. Immunohistochemistry was used to evaluate the expression of HLA-E and HLA-F in gastric cancer specimens. HLA-E and HLA-F expression were seen in the cell membrane. HLA-E and HLA-F expression significantly correlated with depth of invasion, nodal involvement, lymphatic invasion, and venous invasion. No significant correlation between HLA-E and HLA-F expression was found (p<0.05, r=0.24). The five-year survival rate of the HLA-E-positive group and HLA-F-positive group were significantly poorer than that of their respective negative groups. Combination of HLA-E and HLA-F made the p-value smaller than single analysis (p<0.009). This is the first report detailing a clinical implication of HLA-E and HLA-F expression simultaneously in gastric cancer. We identified that the HLA-E and HLA-F in gastric cancer independently affected clinical factors, including postoperative outcome. For HLA-E- or HLA-F-positive gastric cancer, we should settle on a treatment strategy that reinforces the host immune response.