Integrated functional genomics-identified DEAF1 in oxidative stress and hepatocellular carcinoma development.

Hepatocellular carcinoma (HCC) is the third most common cause of death for cancer patients globally, with the overall 5-year survival rate of only 16%. The molecular mechanisms leading to malignant progression of HCC patients remain largely unclear. Hepatocyte nuclear factor 4α (HNF4α) functions as a tumor suppressive transcription factor (TF) in HCC. In this study, we aimed to identify functional HCC susceptibility single nucleotide polymorphisms (SNPs) in HNF4α-binding sites throughout the human genome. We identified 1,274 HNF4α-binding site polymorphisms via a genome-wide screening using TUIFGA (The Updated Integrative Functional Genomics Approach) which we previously developed to recognize cancer susceptibility SNPs within genome-wide TF-binding sites. Among these SNPs, the DEAF1 rs11246280 SNP was significantly associated with HBV-related HCC susceptibility in several case-control studies. Importantly, the rs11246280 SNP could interrupt HNF4α-binding to the DEAF1 promoter and enhance DEAF1 expression. Oncogenic TF DEAF1 binds to the SLC38A3 promoter, elevates glutamine transporter SLC38A3 expression, enhances influx of glutamine and GSH production, leads to reduced ROS levels in cells and, thereby, promotes HCC progression. Our findings highlighted the role of DEAF1 during HCC development via maintaining redox balance, which sheds light on the development of novel cancer therapeutics.