Whole genome bisulfite sequencing reveals epigenetic drivers of chronic chlorpyrifos exposure induced liver cell neoplasia.

Chlorpyrifos (CPF), an organophosphate pesticide (OPP) is used to control wide range of pests and is known for its well-established neurotoxic effects. However, its implications in non-neurological disorders such as cancer, particularly via epigenetic alterations is underexplored. To determine whether chronic exposure to CPF influences liver cancer development through the epigenetic mechanisms, we employed 'Whole Genome Bisulfite Sequencing (WGBS)' to comprehensively assess the epigenetic alterations induced by CPF in liver cells. Our findings revealed that prolonged exposure to sub-lethal doses of CPF (4.07 μM) induces global and gene-specific DNA methylation changes in the liver cells. Notably, we found significant differentially methylated genes (DMGs) enriched across the genome that are primarily involved in liver cancer. Further, functional validation studies (mRNA and protein expression studies) revealed the hypomethylation of oncogenic hub genes such as, FoxO1 and HSPA5; hypermethylation of tumor suppressor genes such as SMAD4 and PARP1, which plays a major role in cell cycle regulation, DNA damage and stress response pathways. Alterations in these molecular targets suggested that chronic CPF exposure disrupts normal epigenetic regulation, potentially shifting the normal cells toward cancer development. Overall, the study highlights the impact of chronic CPF exposure on epigenetics mediated induction of liver cell transformation. The observed epigenetic signature caused by CPF when integrated with the proteomic profile could help us identify putative biomarkers for early detection of CPF- induced liver cancer among the CPF exposed population.