Purpose: Megalin, an endocytic receptor expressed by prostate epithelial cells, can internalize biologically active androgens bound to sex hormone binding globulin. Genetic variation within megalin could potentially influence levels of steroid hormone uptake.
Experimental design: Forty haplotype-tagging single-nucleotide polymorphisms (htSNP) were analyzed in a population-based, case-control study of 553 Caucasian men who were diagnosed with prostate cancer between the ages of 40 and 64 years from the Seattle-Puget Sound region and 534 control men. Prostate cancer risk was estimated using adjusted unconditional logistic regression for both individual SNPs and haplotypes. Risks of disease recurrence/progression and prostate-specific cancer mortality were estimated using Cox proportional hazards regression.
Results: We found no strong evidence of altered risk of developing prostate cancer for any of the htSNPs when they were assessed individually or in haplotypes. However, three htSNPs were significantly associated with both disease recurrence/progression and mortality. Risk of recurrence/progression alone was also associated with five additional htSNPs, and six other htSNPS showed evidence of modification by primary androgen deprivation therapy. Two additional htSNPs were significantly associated with altered risk of death from prostate cancer.
Conclusions: Preliminary results suggest that common genetic variation within the megalin gene could alter both risk of recurrence/progression and prostate-specific cancer mortality. In addition, androgen deprivation therapy effectiveness may be modified by the activity of this gene. To our knowledge, this is the first study that has examined polymorphisms within the megalin gene for associations with prostate cancer risk and outcomes.