Epigenetic mechanisms underlying endometrial cancer (EC) outcomes: race-specific patterns of DNA methylation associated with molecular subtypes and survival.

Endometrial cancer [EC] is the fourth most common cancer in women in the United States. Stark racial disparities are present in EC outcomes in which Black women have significantly higher EC-related mortality than White women. The social and biologic factors that contribute to these disparities are complex, and may include racial differences in epigenetic landscapes. To investigate race-specific epigenetic differences in EC tumor characteristics and outcomes, we utilized the most recent data within the Cancer Genome Atlas (TCGA). Genome-wide CpG methylation data for more than 850 000 CpG sites were analyzed across 245 tumor samples, including 52 from Black women and 181 from White women. Race-adjusted and race-stratified associations among CpG methylation in ECs and molecular subtypes and disease-free survival (DFS) were examined. Race-specific analysis identified subtype-associated CpGs within 9572 genes in tumors from White women, and only 10 genes in tumors that were from Black women. Race-specific analyses also identified survival-associated CpGs with 1119 unique genes identified in tumors from White women, and none identified in tumors from Black women. Genes identified with differential methylation among subtypes included those involved in oxidative stress (HIF3A), and DNA repair (MLH1). Replication cohort data highlighted genes overlapping with those identified within the TCGA, such as G Protein Subunit Beta 1 (GNB1), involved in G-protein signaling, and Interleukin 37 (IL37), involved in cytokine signaling. Identification of these racial differences in EC tumor epigenetic landscapes and associated changes in gene expression may provide insight into strategies to improve outcomes and reduce disparities.