Abstract LB-290: The influence of body size and weight gain on global and gene promoter methylation in a population-based breast cancer study

Abstract

Abstract Purpose. Little is known about how modifiable lifestyle factors, influence the epigenome. Elevated body mass index (BMI, weight kg/height m2) and adult weight gain are associated with increased risk of postmenopausal breast cancer, but the underlying mechanisms are not well understood. We hypothesized that these anthropometric factors may modify DNA methylation status by altering sex-steroid hormones levels and inflammatory markers. Methods. Resources from a population-based study (∼650 postmenopausal cases/∼650 postmenopausal controls) were used to construct logistic regression models. We explored potential modification of the global methylation-breast cancer association by BMI and weight gain using two assays: the luminometric methylation assay (LUMA) and long interspersed elements-1 (LINE-1) in white blood cell DNA. Additionally, we estimated associations between anthropometrics and promoter methylation status in a panel of 13 breast cancer-related genes using ∼600 breast tumor tissues. Results. We observed a multiplicative interaction between LUMA and BMI (p=0.033) in relation to breast cancer. There was a greater than two-fold risk of postmenopausal breast cancer among women in the highest quartile of LUMA for each strata of BMI: age-adjusted odds ratios (95% confidence intervals) were 2.19(1.37, 3.52), 2.91(1.77, 4.80) and 2.51(1.45, 4.33) for women with BMI<25, BMI25-29.9 and BMI≥30, respectively. The observed estimates did not differ, statistically, across BMI categories. Additionally, we found no interactions with LINE-1 and observed no associations between anthropometrics and promoter methylation status in the genes examined. Conclusions. Our data suggest that the association between BMI, weight gain and postmenopausal breast cancer may arise from mechanisms other than DNA methylation. Citation Format: Lauren E. McCullough, Jia Chen, Alexandra J. White, Xinran Xu, Yoon Hee Cho, Patrick T. Bradshaw, Sybil M. Eng, Susan L. Teitelbaum, Mary Beth Terry, Gail Garbowski, Alfred I. Neugut, Hanina Hibshoosh, Regina M. Santella, Marilie D. Gammon. The influence of body size and weight gain on global and gene promoter methylation in a population-based breast cancer study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-290. doi:10.1158/1538-7445.AM2014-LB-290