Epigenetics (Nov 2022)

Epigenetic aberrations of gene expression in a rat model of hepatocellular carcinoma

  • Cayla Boycott,
  • Megan Beetch,
  • Tony Yang,
  • Katarzyna Lubecka,
  • Yuexi Ma,
  • Jiaxi Zhang,
  • Lucinda Kurzava Kendall,
  • Melissa Ullmer,
  • Benjamin S. Ramsey,
  • Sandra Torregrosa-Allen,
  • Bennett D. Elzey,
  • Abigail Cox,
  • Nadia Atallah Lanman,
  • Alisa Hui,
  • Nathaniel Villanueva,
  • Aline de Conti,
  • Tao Huan,
  • Igor Pogribny,
  • Barbara Stefanska

DOI
https://doi.org/10.1080/15592294.2022.2069386
Journal volume & issue
Vol. 17, no. 11
pp. 1513 – 1534

Abstract

Read online

Hepatocellular carcinoma (HCC) is mostly triggered by environmental and life-style factors and may involve epigenetic aberrations. However, a comprehensive documentation of the link between the dysregulated epigenome, transcriptome, and liver carcinogenesis is lacking. In the present study, Fischer-344 rats were fed a choline-deficient (CDAA, cancer group) or choline-sufficient (CSAA, healthy group) L-amino acid-defined diet. At the end of 52 weeks, transcriptomic alterations in livers of rats with HCC tumours and healthy livers were investigated by RNA sequencing. DNA methylation and gene expression were assessed by pyrosequencing and quantitative reverse-transcription PCR (qRT-PCR), respectively. We discovered 1,848 genes that were significantly differentially expressed in livers of rats with HCC tumours (CDAA) as compared with healthy livers (CSAA). Upregulated genes in the CDAA group were associated with cancer-related functions, whereas macronutrient metabolic processes were enriched by downregulated genes. Changes of highest magnitude were detected in numerous upregulated genes that govern key oncogenic signalling pathways, including Notch, Wnt, Hedgehog, and extracellular matrix degradation. We further detected perturbations in DNA methylating and demethylating enzymes, which was reflected in decreased global DNA methylation and increased global DNA hydroxymethylation. Four selected upregulated candidates, Mmp12, Jag1, Wnt4, and Smo, demonstrated promoter hypomethylation with the most profound decrease in Mmp12. MMP12 was also strongly overexpressed and hypomethylated in human HCC HepG2 cells as compared with primary hepatocytes, which coincided with binding of Ten-eleven translocation 1 (TET1). Our findings provide comprehensive evidence for gene expression changes and dysregulated epigenome in HCC pathogenesis, potentially revealing novel targets for HCC prevention/treatment.

Keywords