Polymorphisms of GSTP1 and related genes and prostate cancer risk

Glutathione S-transferase P1 (GSTP1) is markedly downregulated in prostate cancer and prostatic intraepithelial neoplasia compared to normal prostate tissue. Downregulation of GSTP1 may, therefore, be an early event in prostate carcinogenesis. An A → G polymorphism at nucleotide 313 results in an amino acid substitution (Ile105Val) in the substrate binding site of GSTP1 and reduces catalytic activity of GSTP1. In a study of 36 prostate cancer patients, Harries et al. reported that the Ile/Ile genotype is associated with a decreased risk of prostate cancer (odds ratio 0.4 (0.17-0.82)). We sought to confirm this finding and to examine the impact of this polymorphism together with several related polymorphisms implicated as risk factors for carcinogen-associated malignancies. One hundred and seventeen patients with prostate adenocarcinoma and 183 population-based controls were recruited to this case - control study. Genotyping of the GSTP1 (Ile105Val), GSTM1 (null), GSTT1 (null) and CYP1A1 (Ile462Val) genes was performed using polymerase chain reaction (PCR) based techniques on DNA prepared from peripheral blood. A questionnaire was used to collect demographic information from each subject. Cases were significantly older (P < 0.0001) and had significantly greater family history of prostate cancer (P < 0.0001), confirming known risk factors for this disease. By X² analysis, none of the genotype distributions varied among cases and controls. Using a logistic regression model to control for known risk factors we were also unable to demonstrate a significant association with prostate cancer for any of the polymorphisms tested. This population fails to identify a relationship between the above polymorphisms and prostate adenocarcinoma.