Abstract: To investigate the expressions of HLA-A mRNA and HLA-B mRNA in colorectal cancer and their roles in tumorigenesis. MethodsBeta-actin was used as a reference gene to normalize the results. The expression levels of HLA-A and -B mRNA on peripheral blood mononuclear cells (PBMC) were determined by real-time PCR in 50 patients with colorectal cancer, 35 patients with benign colorectal lesions and 42 healthy volunteers whose mean age was similar. The PCR data were analyzed by REST software (relative expression software tool) to get the relative expression ratio of HLA-A and -B mRNA in the three groups. ResultsThe relative expression ratio of PBMC HLA-A and -B mRNA was respectively 0.99±0.47 and 1.13±0.6 in the control group, 0.76±0.59 and 0.84±0.57 in the benign colorectal lesion group and 0.38±0.31 and 0.39±0.35 in the colorectal cancer group. The expression levels of HLA-A and -B mRNA on PBMC in the colorectal cancer group were significantly lower than those in the benign colorectal lesion group and the control group. In the colorectal cancer group, the relative expression ratio of HLA-A mRNA had no significant difference in different expression level in the TNM classificationⅠgroup was significantly higher than that in the TNM classificationⅡ and Ⅳ groups(P＜0.05), and there were no significant differences of HLA-B mRNA among different TNM classifications. ConclusionHLA-A and -B mRNA on PBMC in colorectal cancer are related to host immunity and play important roles in the process of anti-cancer.

Key words: Colorectal neoplasms, Peripheral blood mononuclear cell, Human leukocyte antigen A, Human leukocyte antigen B