OCT4 as a target of miR-34a stimulates p63 but inhibits p53 to promote human cell transformation

Cell Death Dis. 2014 Jan 23;5(1):e1024. doi: 10.1038/cddis.2013.563.

Abstract

Human cell transformation is a key step for oncogenic development, which involves multiple pathways; however, the mechanism remains unclear. To test our hypothesis whether cell oncogenic transformation shares some mechanisms with the process of reprogramming non-stem cells to induced pluripotent stem cells (iPSC), we studied the relationship among the key factors for promoting or inhibiting iPSC in radiation-transformed human epithelial cell lines derived from different tissues (lung, breast and colon). We unexpectedly found that p63 and OCT4 were highly expressed (accompanied by low expressed p53 and miR-34a) in all transformed cell lines examined when compared with their non-transformed counterparts. We further elucidated the relationship of these factors: the 3p strand of miR-34a directly targeted OCT4 by binding to the 3' untranslated region (3'-UTR) of OCT4 and, OCT4, in turn, stimulated p63 but inhibited p53 expression by binding to a specific region of the p63 or p53 promoter. Moreover, we revealed that the effects of OCT4 on promoting cell oncogenic transformation were by affecting p63 and p53. These results support that a positive loop exists in human cells: OCT4 upregulation as a consequence of inhibition of miR-34a, promotes p63 but suppresses p53 expression, which further stimulates OCT4 upregulation by downregulating miR-34a. This functional loop contributes significantly to cell transformation and, most likely, also to the iPSC process.

Publication types

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

MeSH terms

  • Cell Differentiation
  • Cell Transformation, Neoplastic*
  • Gene Expression Regulation*
  • Humans
  • Induced Pluripotent Stem Cells / cytology
  • Induced Pluripotent Stem Cells / metabolism*
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Octamer Transcription Factor-3 / genetics*
  • Octamer Transcription Factor-3 / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Tumor Suppressor Protein p53 / genetics*
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism

Substances

  • MIRN34 microRNA, human
  • MicroRNAs
  • Octamer Transcription Factor-3
  • POU5F1 protein, human
  • TP63 protein, human
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins