Association of endothelin-1 gene single-nucleotide polymorphisms and haplotypes with risk of hormone refractory prostate cancer

Androgen deprivation is often the treatment of choice for patients with a new diagnosis of metastatic or locally advanced prostate cancer (CaP). However, most CaP patients showing a first response to androgen deprivation will progress to a hormone refractory phase of the disease (HRPC) with a much poorer prognosis. Accumulating evidence suggests that endothelin-1 (ET-1) plays an important role in CaP progression. Single nucleotide polymorphisms (SNPs) of the ET-1 gene reportedly have been associated with cancer progression and chemoresistance. In the present study, we explored the association of SNPs and haplotypes of the ET-1 gene with the risk of HRPC. We genotyped three SNPs (rs1800541, rs2070699 and rs5370) in the ET-1 gene in a case-control study; 234 CaP patients who developed HRPC within six years after androgen deprivation therapy was used as HRPC cases, and 234 age- and primary therapy-matched CaP patients who had not developed HRPC within six years after androgen deprivation therapy were used as non-HRPC controls. Our results revealed that the G allele at rs1800541 and the G allele at rs2070699 were respectively associated with reduced and increased risk of HRPC at borderline statistical significance (p=0.047 and p=0.058, respectively). With adjustment for potential confounders including body mass index, initial Gleason score at diagnosis of CaP, and post-treatment nadir serum PSA level, we found that rs1800541-rs2070699 TG haplotype was significantly associated with increased risk of HRPC (p=0.033; adjusted OR, 2.10; 95% CI, 1.37-5.04). In conclusion, this study provides the first evidence that a 2-SNP haplotype of the ET-1 gene is associated with increased risk of HRPC, which adds new insights into early identification of CaP patients who are likely to develop HRPC in a later stage of the disease.