Hypomethylation and induction of retinoic acid receptor beta 2 by concurrent action of adenosine analogues and natural compounds in breast cancer cells

Eur J Pharmacol. 2010 Jul 25;638(1-3):47-53. doi: 10.1016/j.ejphar.2010.04.032. Epub 2010 May 3.


DNA methylation is considered as a potential cause of aberrations in regulation of gene expression during carcinogenesis. Therefore, changes in DNA methylation patterns may be targets for chemoprevention. In the present study, we investigated effects of all-trans retinoic acid (ATRA), vitamin D(3), and resveratrol alone and in combination with adenosine analogues: 2-chloro-2'-deoxyadenosine (2CdA) and 9-beta-D-arabinosyl-2-fluoroadenine (F-ara-A), on methylation and expression of retinoic acid receptor beta 2 (RAR beta 2) in MCF-7 and MDA-MB-231 breast cancer cell lines. Alterations in methylation and expression levels after treatment of cells with the tested compounds were evaluated by methylation-sensitive restriction analysis (MSRA) and real-time PCR, respectively. RAR beta 2 promoter in the tested fragment was partially methylated in MCF-7 cells and non-methylated in MDA-MB-231 cells. In MCF-7 cells, all compounds, except for resveratrol, inhibited promoter methylation and increased expression of RAR beta 2. All natural compounds improved the action of 2CdA and F-ara-A on RAR beta 2 methylation and/or expression. Combination of ATRA or vitamin D(3) with 2CdA was the most effective. In MDA-MB-231 cells, only 2CdA, F-ara-A, and ATRA induced RAR beta 2 expression without any notable effects in combined treatment. Our results demonstrate that both natural compounds and adenosine analogues are able to reduce promoter methylation and/or induce expression of RAR beta 2 in non-invasive MCF-7 cells. Furthermore, the natural compounds improve effects of adenosine analogues, however only at early non-invasive stages of carcinogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / pharmacology*
  • Antineoplastic Agents / pharmacology*
  • Breast Neoplasms / metabolism*
  • Cell Line, Tumor
  • Cholecalciferol / pharmacology
  • Cladribine / pharmacology
  • DNA Methylation / drug effects*
  • Drug Screening Assays, Antitumor
  • Drug Synergism
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Promoter Regions, Genetic / drug effects
  • Receptors, Retinoic Acid / metabolism*
  • Resveratrol
  • Stilbenes / pharmacology
  • Transcriptional Activation / drug effects*
  • Tretinoin / pharmacology
  • Vidarabine / analogs & derivatives
  • Vidarabine / pharmacology


  • Antineoplastic Agents
  • Receptors, Retinoic Acid
  • Stilbenes
  • retinoic acid receptor, beta2, human
  • Cholecalciferol
  • Cladribine
  • Tretinoin
  • Vidarabine
  • Adenosine
  • fludarabine
  • Resveratrol