Down-regulation of HLA-A mRNA in peripheral blood mononuclear cell of colorectal cancer

Purpose It has been demonstrated that the alteration of human leukocyte antigen (HLA) class I expression frequently occurs in colorectal tumor. Previous studies mainly focused on the expression of HLA-A in tumor cells. The expression of HLA-A in peripheral blood mononuclear cells (PBMC) was unknown. To develop a non-invasive diagnostic method for colorectal cancer (CRC), this work investigated the expression of HLA-A mRNA in PBMC in patients with CRC. Methods Real-time quantitative RT-PCR was used to study the expression of HLA-A mRNA in PBMC from 48 patients with colorectal cancer, 38 patients with benign colorectal lesions, 20 patients with rheumatoid arthritis, 20 patients with esophageal cancer and 40 healthy individuals. Protein chip was utilized to detect the levels of serum CEA, CA 19-9, and CA 242 in all the cases. Overall results from the two methods were compared. Results The relative expression of HLA-A mRNA in PBMC was 1.11 +/- 0.45 in healthy group, 0.81 +/- 0.42 in benign colorectal lesion group, and 0.39 +/- 0.34 in cancer group, respectively. The diagnostic sensitivity of HLA-A mRNA, CEA, CA19-9, and CA242 was 81%, 59%, 61%, and 63%, and their diagnostic specificity was 75%, 64%, 52%, and 67%, respectively. Conclusions The expression of HLA-A mRNA in PBMC from colorectal cancer group was significantly lower than those in both benign group and healthy group (P<0.001). It could be potentially developed as a tumor assistant marker in future.