Suppression of DPYD expression in RKO Cells via DNA methylation in the regulatory region of the DPYD promoter: A potentially important epigenetic mechanism regulating DPYD expression

Xue Zhang, Richie Soong, Kangsheng Wang, Lin Li, James R. Davie, Vincenzo Guarcello, Robert B. Diasio

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Dihydropyrimidine dehydrogenase (DPD) is one of the factors that determine the efficacy and toxicity of 5-fluorouracil. Variations in DPD activity may result from alterations at the transcriptional level of the DPYD gene. Heterogeneity in DPYD expression has been reported, but the molecular mechanisms responsible for this remain unclear. We investigated methylation of the DPYD promoter as a mechanism for transcriptional regulation of DPYD in the RKO colorectal cancer cell line. We demonstrate that the active transcription machinery for DPYD is present in RKO cells, but promoter binding of Sp1, a transactivator of DPYD, was inhibited, which on subsequent examination was shown to be associated with dense promoter methylation. Treatment with 5-aza-2′-deoxycytidine alone or the combination of 5-aza-2′- deoxycytidine and trichostatin A induced demethylation of the promoter and markedly increased the DPYD mRNA level in RKO cells but not in unmethylated WiDr cells. Furthermore, in vitro methylation of the DPYD promoter decreased promoter activity. These data suggest an important role for methylation in DPYD suppression. The transcriptional suppression of DPYD by methylation may be responsible for the increased 5-fluorouracil sensitivity observed in some patients. This may also provide insight into the mechanism underlying the downregulation of DPYD in some colorectal cancers.

Original languageEnglish (US)
Pages (from-to)337-346
Number of pages10
JournalBiochemistry and Cell Biology
Volume85
Issue number3
DOIs
StatePublished - Jun 2007

Keywords

  • Colorectal cancer RKO cell line
  • DNA methylation
  • DPYD
  • Dihydropyrimidine dehydrogenase
  • Promoter

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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