Let-7 and miR-200 microRNAs: guardians against pluripotency and cancer progression

Cell Cycle. 2009 Mar 15;8(6):843-52. doi: 10.4161/cc.8.6.7907. Epub 2009 Mar 22.


Micro (mi)RNAs are emerging as important regulators of cellular differentiation, their importance underscored by the fact that they are often dysregulated during carcinogenesis. Two evolutionary conserved families, let-7 and miR-200, regulate key differentiation processes during development. Loss of let-7 in cancer results in reverse embryogenesis and dedifferentiation, and miR-200 has been identified as a powerful regulator of epithelial-to-mesenchymal transition (EMT). Recent findings have connected let-7 with stem cell maintenance and point at a connection between EMT and stem cell formation. A part of tumor progression can be viewed as a continuum of progressive dedifferentiation (EMT) with a cell at the endpoint that has stem cell-like properties. I propose that steps of this process are driven by specific changes in the expression of let-7 and miR-200 family members.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Cell Differentiation / genetics
  • Humans
  • Mice
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Neoplasms / metabolism
  • Neoplasms / pathology*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology*
  • Pluripotent Stem Cells / metabolism
  • Pluripotent Stem Cells / pathology*
  • Signal Transduction / physiology
  • Transcription Factors / metabolism


  • MIRN200 microRNA, human
  • MicroRNAs
  • Transcription Factors
  • mirnlet7 microRNA, human