Abstract 3314: Heritable methylation marks associated with prostate and breast cancer risk

Abstract

Abstract While most epigenetic marks are reprogrammed during early embryogenesis, some studies have reported Mendelian-like inheritance of germline DNA methylation in particular in cancer susceptibility genes. For instance, individuals with MLH1 silenced throughout the soma fit the clinical criteria for hereditary nonpolyposis colorectal cancer that is indistinguishable from the syndrome resulting from germline mutations in MLH1. Research using multiple-case breast cancer families has shown that LINE-1 and Sat2 DNA methylation levels are lower in individuals with a strong family history. Family clustering of cancer could therefore be due to epigenetic as well as genetic and shared environmental factors. We have recently identified heritable methylation marks associated with breast and/or prostate cancer susceptibility by conducting a study involving 45 Australian multi-generational families with multiple cases of breast or prostate cancer who are not known to carry genetic mutations in cancer susceptibility genes. We developed and applied a new statistical method to identify heritable methylation marks based on complex segregation analysis and identified 24 and 41 methylation marks significantly associated with breast and prostate cancer risk respectively. Several marks across VTRNA2-1, a gene located in a differentially methylated region that is involved in imprinting and shows allele-specific methylation, were associated with heritable risk of both cancer types. A proportion of all identified marks were found to be associated with cancer risk in independent nested case-control studies (ie outside of the multiple-case family setting). We are expanding these successful studies to include additional families and to estimate HRs and age-specific cumulative risks of cancer associated with these marks to enable the incorporation of this information into clinical tools for risk prediction. Citation Format: Melissa C. Southey, Jihoon E. Joo, James G. Dowty, Roger L. Milne, EE Ming Wong, Pierre-Antoine Dugué, Dallas English, John L. Hopper, David E. Goldgar, Graham G. Giles. Heritable methylation marks associated with prostate and breast cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3314.