Epigenetic dysregulation of liver detoxification genes in hepatocellular carcinoma

Adenocarcinomas of the prostate, ovary and colon are associated with higher mortality in Americans of African descent, compared to Whites. Our overarching hypothesis is that clearance of environmental toxins is less efficient in African Americans (AA) that Whites and this bioaccumulation in target tissues increases risk of adenocarcinomas. The proposed research in this pilot will examine the role epigenetics in the dysregulation of UGT2 genes and associated gene expression.  We will assess the association of DNA methylation marks with hepatocellular carcinoma and normal biopsied or resected tissue with expression of the enzymes.  Our unpublished data suggests that methylation status of specific CpG marks are associated with prostate cancer versus normal tissue. We have used bioinformatics approaches to mine uploaded public databases to identify CpG marks in target UGT genes that are associated with malignant tumors when compared to normal adjacent tissue or other controls. We have extended this search to other cancers that disproportionately affect African Americans, including liver and ovarian cancers. In this pilot, we will leverage liver tissue samples collected by CHHE researchers to determine if the CpG marks in UGT2 genes will comprise a “signature” will be related to liver tissue due to the common expression. We will use pyrosequencing of DNA isolated from human liver tissue to determine DNA methylation marks associated with demethylation and assess the UGT2 RNA transcriptome with RNAseq.  We will use modified methylation environments induced in hepatic cancer cell lines and assess the influence first on gene expression. We have shown with previous NIEHS/NIH funding that mice null for the UGT2 locus, a subfamily of the UGT superfamily of enzymes have impaired clearance of bisphenol A, a well-characterized environmental pollutant.  This data will serve to support future proposals that will study the impact of epimutations and genetic variants on the glucuronidation on environmental toxins using a humanized mouse model of the UGT2 locus.