Prostate carcinoma risk and allelic variants of genes involved in androgen biosynthesis and metabolism pathways.

Abstract

Ethnicity, when it is used to mean shared genetic inheritance within a group, has become one of the most important factors in determining prostate carcinoma risk. Genetic polymorphisms were hypothesized to be the probable explanation for differences in risk among ethnic groups. The authors evaluated the association between polymorphisms in genes involved in the androgen biosynthesis and metabolism pathway and the risk of prostate carcinoma. Two hundred twenty-six patients with the pathologic diagnosis of sporadic prostate tumor and 156 healthy matched (age, ethnic group) male controls from a large epidemiologic cohort were genotyped for previously described polymorphisms in the androgen receptor (AR), 5alpha-reductase type II (SRD5A2), p450c17 (CYP17), and aromatase (CYP19) genes. The different polymorphisms in prostate carcinoma patients also were analyzed according to age of onset, preoperative prostate-specific antigen level, tumor stage, and tumor grade. The distribution of the tetranucleotide simple tandem repeat polymorphism (STRP) in intron 4 of CYP19 was significantly different in control and cancer patients (P = 0.012). The 171 allele and the 187 allele were associated with prostate carcinoma risk (P = 0.05 and P = 0.045, respectively). Conversely, no association was observed between prostate carcinoma risk and the other polymorphisms studied as follow: the CAG repeat in exon 1 of AR, the (TA)n dinucleotide repeat polymorphism in the 3' untranslated region, and the A49T or V89L substitutions in SDR5A2, the single base pair (bp) (a T to C transition) polymorphism that creates an additional Sp1-type (CCACC box) promoter site in CYP17. In prostate carcinoma patients, CAG repeats of AR, and TA repeats of SDR5A2 are associated with age of onset (P = 0.05 and P < 0.001, respectively). The association between the 171-bp allele of CYP19 and prostate carcinoma risk suggests that aromatase could be used as a new indicator for prostate carcinoma prevention in men of White French ethnogeographic origin. Conversely, it is possible that an individual carries both a high- and a low-risk marker (e.g., CYP17 A2 allele and V89L in SRD5A2) resulting in no overall difference in risk observed across the population. For these reasons, the development of a polygenic model, incorporating multiple loci from the individual genes may maximize the chance of identifying individuals with high-risk genotypes.