Epigenome-wide association analysis of pancreatic exocrine cells from high-fat- and normal diet-fed mice and its potential use for understanding the oncogenesis of human pancreatic cancer.

Aberrant DNA methylation is associated with oncogenesis of various human cancers, including pancreatic cancer (PC). PC is the seventh most common cancer, and obesity is a known high-risk factor. However, whether obesity influences DNA methylation in pancreatic exocrine cells and if this influences PC development remain unclear. Here, we performed an epigenome-wide analysis of isolated pancreatic exocrine cells obtained from mice with high-fat-diet-induced obesity (DIO). Using the Illumina Mouse Methylation BeadChip array (280K), we identified 316 differentially methylated regions (DMRs) that were enriched for cellular processes, such as DNA repair, transcription regulation, and cell proliferation, which confirmed obesity-related dysregulation of certain metabolic processes in the pancreatic cells in DIO mice. Comparing the DMRs with those in stage IB PC helped identify 82 overlapping DMRs. Three pathways including the cell hypertrophy pathway involving PLC, PKC, SMAD2/3, and TRKA; the metabolic control pathway involving CREB and AMPK; and the potassium regulation pathway involving K+ -channels, were shared between the pancreatic exocrine cells from DIO mice and stage IB PC. Enhanced alteration in the methylation level was observed in PC compared to that in DIO mice. These findings indicated that obesity influences DNA methylation in pancreatic exocrine cells of DIO mice, and persistent dysregulation of DNA methylation in individuals with obesity may result in PC development.