Genome-wide methylation and expression differences in HPV(+) and HPV(-) squamous cell carcinoma cell lines are consistent with divergent mechanisms of carcinogenesis

Epigenetics. 2011 Jun;6(6):777-87. doi: 10.4161/epi.6.6.16216. Epub 2011 Jun 1.

Abstract

Oncogenic human papillomaviruses (HPV) are associated with nearly all cervical cancers and are increasingly important in the etiology of oropharyngeal tumors. HPV-associated head and neck squamous cell carcinomas (HNSCC) have distinct risk profiles and appreciate a prognostic advantage compared to HPV-negative HNSCC. Promoter hypermethylation is widely recognized as a mechanism in the progression of HNSCC, but the extent to which this mechanism is consistent between HPV(+) and HPV(-) tumors is unknown. To investigate the epigenetic regulation of gene expression in HPV-induced and carcinogen-induced cancers, we examined genome-wide DNA methylation and gene expression in HPV(+) and HPV(-) SCC cell lines. We used two platforms: the Illumina Infinium Methylation BeadArray and tiling arrays, and confirmed illustrative examples with pyrosequencing and quantitative PCR. These analyses indicate that HPV(+) cell lines have higher DNA methylation in genic and LINE-1 regions than HPV(-) cell lines. Differentially methylated loci between HPV(+) and HPV(-) cell lines significantly correlated with HPV-typed HNSCC primary tumor DNA methylation levels. Novel findings include higher promoter methylation of polycomb repressive complex 2 target genes in HPV(+) cells compared to HPV(-) cells and increased expression of DNMT3A in HPV(+) cells. Additionally, CDKN2A and KRT8 were identified as interaction hubs among genes with higher methylation and lower expression in HPV(-) cells. Conversely, RUNX2, IRS-1 and CCNA1 were major hubs with higher methylation and lower expression in HPV(+) cells. Distinct HPV(+) and HPV(-) epigenetic profiles should provide clues to novel targets for development of individualized therapeutic strategies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Carcinoma, Squamous Cell / genetics*
  • Carcinoma, Squamous Cell / metabolism*
  • DNA Methylation
  • Female
  • Gene Expression Regulation*
  • Genome-Wide Association Study
  • Humans
  • Male
  • Middle Aged
  • Papillomaviridae*
  • Promoter Regions, Genetic
  • Tumor Cells, Cultured