Abstract 806: SNPs in vitamin D-related genes are associated with prostate cancer aggressiveness in the North Carolina-Louisiana Prostate Cancer Project (PCaP)
Authors: Steck Susan E. , Woloszynska-Read Anna , Antwi Samuel , Zhang Hongmei , Arab Lenore , Fontham Elizabeth T.H. , Mohler James , Su L. Joseph , Xiao Feifei , Smith Gary , Trump Donald , Johnson Candace , Bensen Jeannette 
Published: July 2016

Introduction: African Americans have higher incidence of, and mortality from, prostate cancer (PCa) compared to other racial/ethnic groups. Frequency of polymorphisms in genes involved in vitamin D metabolism, transport, and activity differ by race/ethnicity. Examining the association between polymorphisms in vitamin D-related genes and PCa aggressiveness may explain differing susceptibility to aggressive PCa among individuals and across different racial/ethnic groups.

Methods: TagSNPs (n = 315) in 13 genes (VDR, GC, CYP24A1, CYP27A1, CYP27B1, CYP2R1, CYP3A4, DHCR7, CASR, NADSYN1, RXRA, RXRB, RXRG) were genotyped using Illumina GoldenGate or Sequenom assays in 524 African-American and 657 European-American men with newly-diagnosed PCa from PCaP. DNA extracted from blood samples collected at enrollment was stored at -80C prior to analyses. Research subjects were classified as high aggressive if Gleason sum ≥8, or Gleason score (4+3), or PSA &gt;20 ng/ml, or Gleason score (3+4) AND clinical stage = T3-T4. The comparison group (low aggressive) included research subjects with Gleason sum &lt;7 AND Stage T1-T2 AND PSA &lt; 9 ng/ml. Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated for high aggressive PCa for each SNP using logistic regression with adjustment for age and proportion of African ancestry. Associations were considered statistically significant at p&lt;0.05. A polygenic score based on a previous study of SNP predictors of serum 25-hydroxy-vitamin D levels was calculated utilizing SNPs in the GC, CYP24A1, CYP2R1, and NADSYN1 genes.

Results: Among African Americans, 21 SNPs were associated with PCa aggressiveness. The variant allele was associated negatively or positively with high aggressive PCa in eleven and ten SNPs, respectively. For example, two SNPs in the vitamin D binding protein gene known as GC, were inversely associated (rs222054: OR, 0.55, 95%CI, 0.38-0.80; and rs16847028: OR, 0.61, 95%CI, 0.39-0.94). Among European Americans, the variant allele was inversely associated with high aggressive PCa for four SNPs in three genes (CASRrs3863977; CYP24A1rs4809960; RXRArs1007971; and RXRArs3118526), and positively associated with high aggressive PCa for three SNPs in the CYP27B1 gene (rs703842, rs4646536, and rs10877013). There was no association between higher number of ‘low vitamin D’ alleles in the four SNPs that comprised the polygenic score and PCa aggressiveness for either race.

Conclusions: Polymorphisms in genes involved in vitamin D etabolism and activity, the vitamin D binding protein and calcium sensing receptor were associated with PCa aggressiveness, and there was no overlap in SNPs between race groups. Our ongoing work will examine interaction between polymorphisms of vitamin D-related genes and vitamin D metabolite levels on PCa aggressiveness.

Citation Format: Susan E. Steck, Anna Woloszynska-Read, Samuel Antwi, Hongmei Zhang, Lenore Arab, Elizabeth T.H. Fontham, James Mohler, L. Joseph Su, Feifei Xiao, Gary Smith, Donald Trump, Candace Johnson, Jeannette Bensen. SNPs in vitamin D-related genes are associated with prostate cancer aggressiveness in the North Carolina-Louisiana Prostate Cancer Project (PCaP). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 806.