County poverty levels influence genome-wide DNA methylation profiles in African American and European American women

Our pilot study examined global DNA methylation and telomere length (TL) using DNA from saliva samples provided by 39 participants in the Arkansas Rural Community Health (ARCH) Study. TL was quantified by qPCR, and DNA methylation and DNA methylation age was assessed using the Illumina 850K Epic BeadChip. Ingenuity Pathway Analysis (IPA) was performed to identify biological pathways that were DM between residents of counties with high or low poverty rates and by race [African American descent (AA) versus European American (EA) descent]. Among AA women, hypermethylation was more common in AA residents of counties with low compared to high poverty rates (70% vs. 30%). The top canonical pathways impacted by differential methylation were related to glucocorticoid receptor, p53, and estrogen-dependent breast cancer signaling in AA women. EA women living in low-poverty counties exhibited less hypermethylation of CpGs than those living in high-poverty counties (27% vs. 73%). The top canonical pathways were related to hereditary breast cancer, glucocorticoid receptor, androgen and PI3K/AKT signaling. Several genes involved in telomere maintenance were shown to be DM by county poverty levels. Therefore, the finding of this pilot study suggests county poverty levels may impact DNA methylation patterns in breast cancer-related pathways as well as genes involved in telomere maintenance. Larger studies should confirm our findings.