Relationship between HLA-DR antigen and HLA-DRB1 alleles and prostate cancer in Japanese men

Purpose: Human leukocyte antigens (HLA) are cell surface glycoproteins playing a key role in the immune system. In some cancers, changes in major histocompatibility complex (MHC) class I and II expression, usually a reduction or loss of these molecules, appear to provide a mechanism whereby tumour cells may escape host immunity. We investigated the relationship between HLA, especially class II, molecules and prostate cancer in Japanese men using molecular techniques. Materials and methods: HLA class II typing was performed by the polymerase chain reaction-sequence specific primer (PCR- SSP) method of analysis and/or a commercial rapid assay based on the PCR followed by reverse dot-blot hybridization of the PCR products (Inno-LiPA assay). Allele frequencies were calculated. HLA allele frequencies reported in 1216 healthy Japanese individuals were used as the control data. Differences in allele frequency between subjects and the control group were analyzed by the chi-square test. The relationship between HLA antigens/alleles and prostate cancer is expressed in terms of relative risk (RR). Results: The frequencies of HLA-DR4 were significantly higher in Japanese men with prostate cancer than in the healthy control group (gene frequency 36.2% vs. 26.3% in control, p<0.05), although the relative risk of prostate cancer was less than 2. Furthermore, the frequencies of HLA-DRB1- 0406, 0410 and 1405 allele were significantly higher in the prostate cancer group than in the control group (allele frequency was 7.3%, 4.5% and 5.4% vs. 3.03%, 1.79% and 2.22%, p<0.05, respectively). RR of those HLA-DRB1 allele for prostate cancer was 2.6 in each allele. Conclusions: HLA molecules may be useful for the early detection of prostate cancer as a risk factor, and also for recognizing cancer activity by using them as a marker helpful in the choice of appropriate treatment by predicting prognosis.