P4-11-09: Polymorphisms Related to Steroid Hormone Concentrations in Nipple Aspirate Fluid (NAF).

Background The steroid hormone concentrations in NAF are variable, and differ significantly from systemic levels. Single nucleotide polymorphisms (SNPs) in genes associated with the metabolism of estradiol (E2) to 4-hydroxyestradiol (CYP1B1) and a transporter of steroid sulfate uptake (SLCO2B1) may partially determine the steroid hormone level in NAF, and thereby contribute to breast cancer risk. We determined the relationship between SNPs of interest and the measured concentrations of sex steroids in NAF. Methods : Blood samples of 263 women at high risk of breast cancer who produced NAF were extracted for gDNA, and 40 ng of gDNA was used to determine the presence of the selected SNPs or their wild type genes in all subjects by the Taqman Drug Metabolism genotyping assays (Applied Biosystems). The concentrations of six steroid hormones, estradiol(E2), estrone (E1), progesterone (P4), testosterone (T), androstenedione (A4), and dehydroepiandrosterone (DHEA), from NAF were measured by immunoassay procedures after extraction and purification by High Pressure Liquid Chromatography. Comparisons of NAF steroid hormone concentrations were made for the polymorphism and wild type groups using the nonparametric Mann-Whitney tests (significance p Results : 46% of the subjects carried the V432K polymorphism of CYP1B1 (rs 1056836, C>G), and 45% of the subjects carried the S486F polymorphism of SLCO2B1 (rs 2851069, C>T). All NAF hormone concentrations are represented as a median with the quartile range (25%, 75%). The NAF P4 levels of the V432K mutation carriers of CYP1B1 were significantly lower than those of subjects with the wild type alleles: 3.54(1.62, 8.79) ng/mL and 7.65(2.13, 27.77) ng/mL, respectively (p = 0.002). Those with the S486F polymorphism of SLCO2B1 had significantly higher E1 levels than the wild type subjects: 0.35(0.14, 1.12) ng/mL and 0.25(0.11, 0.59) ng/mL, respectively (p = 0.026) and significantly lower P4 levels: 3.77(1.71, 11.53) ng/mL and 6.65 (2.34, 22.24) ng/mL, respectively (p=0.021). In addition, we found that the women carrying both the V432K and S486F mutations had significantly lower P4 levels than the women carrying only the S486F mutation: 2.43(1.45, 6.67) ng/mL and 6.94(2.13, 26.64) ng/mL (p=0.013). No associations were found between the other hormones and these polymorphisms. Conclusions : The anticipated effects of CYP1B1 in increasing clearance of E2 and E1 were not observed. Instead, NAF E1 concentrations were significantly increased. In subjects with the S486F polymorphism of SLCO2B1 the expected decrease in E1 and E2 in NAF was not observed; nor was the DHEA concentration decreased. These expectations were based on the reported lower activity of the S486F gene product. The decreased concentrations of NAF P4 associated with both polymorphisms are difficult to explain. Additional studies are required to understand the observed associations, but these findings raise the possibility that low P4 levels in NAF may be genetically determined, and suggest the hypothesis that this polymorphism may be related to a decreased risk of breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-11-09.