CTCF and BORIS regulate Rb2/p130 gene transcription: a novel mechanism and a new paradigm for understanding the biology of lung cancer

Mol Cancer Res. 2011 Feb;9(2):225-33. doi: 10.1158/1541-7786.MCR-10-0493.

Abstract

Although innumerable investigations regarding the biology of lung cancer have been carried out, many aspects thereof remain to be addressed, including the role played by the retinoblastoma-related protein Rb2/p130 during the evolution of this disease. Here we report novel findings on the mechanisms that control Rb2/p130 gene expression in lung fibroblasts and characterize the effects of Rb2/p130 deregulation on the proliferative features of lung cancer cells. We revealed for the first time that in lung fibroblasts the expression of Rb2/p130 gene is directly controlled by the chromatin insulator CCCTC-binding factor, CTCF, which by binding to the Rb2/p130 gene promoter induces, and/or maintains, a specific local chromatin organization that in turn governs the transcriptional activity of Rb2/p130 gene. However, in lung cancer cells the activity of CTCF in controlling Rb2/p130 gene expression is impaired by BORIS, a CTCF-paralogue, which by binding to the Rb2/p130 gene could trigger changes in the chromatin asset established by CTCF, thereby affecting CTCF regulatory activity on Rb2/p130 transcription. These studies not only provide essential basic insights into the molecular mechanisms that control Rb2/p130 gene expression in lung cancer, but also offer a potential paradigm for the actions of other activators and/or corepressors, such as CTCF and BORIS, that could be crucial in explaining how alterations in the mechanism regulating Rb2/p130 gene expression may accelerate the progression of lung tumors, or favor the onset of recurrence after cancer treatment.

MeSH terms

  • Binding Sites
  • CCCTC-Binding Factor
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Carcinoma, Small Cell / genetics
  • Carcinoma, Small Cell / pathology
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • Chromosome Positioning / genetics
  • DNA-Binding Proteins / metabolism*
  • Fibroblasts / metabolism
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Lung Neoplasms / genetics*
  • Lung Neoplasms / pathology
  • Open Reading Frames / genetics
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Repressor Proteins / metabolism*
  • Retinoblastoma-Like Protein p130 / genetics*
  • Retinoblastoma-Like Protein p130 / metabolism
  • Transcription, Genetic*

Substances

  • CCCTC-Binding Factor
  • CTCF protein, human
  • CTCFL protein, human
  • DNA-Binding Proteins
  • Repressor Proteins
  • Retinoblastoma-Like Protein p130