Poster Topical Area: Medical Nutrition

Location: Hall D

Poster Board Number: 653

P14-028 - Hepatocytes (CWSV1) with CRISPR-dCas9 Deletion of the Betaine Homocysteine Methyltransferase (Bhmt) gene Exhibit Hepatocellular Carcinoma Phenotype.

Monday, Jun 11
8:00 AM – 3:00 PM

One-carbon metabolism, including folate and methionine cycles, is considered a central pathway for adequate methylation and redox maintenance, among other functions. Specifically, in the methionine cycle, betaine homocysteine methyl transferase (BHMT) generates approximately half the methionine necessary for S-adenosymethonine synthesis needed for DNA and histone methylation. Our research group has demonstrated that deletion of Bhmt in mice is associated with spontaneous development of hepatocellular carcinomas (HCC). We also demonstrated that this event is in part mediated through the downregulation of IQ motif-containing GTPase activating protein 2 (Iqgap2) and Proteinase-Activated Receptor 3 (F2rl2) genes. OBJECTIVES. We hypothesize that deletion of Bhmt causes endoplasmic reticulum stress triggering changes in metabolites, and gene and protein expression resulting in HCC. METHODS. To gain insight into the potential mechanism, we created Bhmt knockout CWSV1 hepatic cells via the CRISPR-dCas9 system (Bhmt-KO). RESULTS. Our preliminary results show that Bhmt-KO cells exhibit upregulation of fibroblast growth factor 21 gene (Fgf21), downregulation of Iqgap2 and F2rl2 genes, and anchorage independent growth in agar, which correlates strongly with tumorigenecity. CONCLUSIONS.These results mimic the phenotype observed in Bhmt knockout mouse liver. Since our in vitro cell model mimics the in vivo findings, studies are ongoing to determine metabolic, protein and gene expression changes leading to HCC in our Bhmt-KO cells. We propose that Bhmt deletion disrupts metabolic homeostasis leading to changes in gene expression thereby causing HCC.

Funding Source:

This work was funded by grants from the NIH (DK115380, DK056350).

CoAuthors: Stephen Orena – University of North Carolina Chapel Hill; Walter Friday – University of North Carolina; Steven Zeisel – University of North Carolina Chapel Hill

Isis Trujillo

Postdoctoral Research Associate
University of North Carolina at Chapel Hill
Kannapolis, North Carolina