title: Sulforaphane Alone and in Combination  with Clofarabine Epigenetically Regulates  the Expression of DNA Methylation-Silenced  Tumour Suppressor Genes in Human Breast  Cancer Cells.
abstract: OBJECTIVE
  Sporadic breast cancer is frequently associated with aberrant DNA methylation patterns that are reversible and responsive to environmental factors, including diet. In the present study, we investigated the effects of sulforaphane (SFN), a phytochemical from cruciferous vegetables, on the methylation and expression of PTEN and RARbeta2 tumour suppressor genes as well as on the expression of regulators of DNA methylation reaction, DNMT1 , p53 , and p21 , in MCF-7 and MDA-MB-231 human breast cancer cells with different invasive potential. We also evaluate the role of SFN epigenetic effects in support of therapy with clofarabine (ClF) that was recently shown to modulate the epigenome as well.
  
  
  METHODS
  Promoter methylation and gene expression were estimated using methylation-sensitive restriction analysis and real-time PCR, respectively.
  
  
  RESULTS
  In both MCF-7 and MDA-MB-231 cells, SFN at IC 50 (22 and 46 μ M , respectively) and a physiologically relevant 10 μ M concentration lead to hypomethylation of PTEN and RARbeta2 promoters with concomitant gene upregulation. The combination of SFN and ClF enhances these effects, resulting in an increase in cell growth arrest and apoptosis at a non-invasive breast cancer stage.
  
  
  CONCLUSIONS
  Our findings provide evidence that SFN activates DNA methylation-silenced tumour suppressor genes in breast cancer cells and may contribute to SFN-mediated support of therapy with an anti-cancer drug, ClF, increasing its applications in solid tumours.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Lubecka-Pietruszewska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kaufman-Szymczyk
authors.forename: Barbara
authors.initials: B
authors.lastname: Stefanska
authors.forename: Barbara
authors.initials: B
authors.lastname: Cebula-Obrzut
authors.forename: Piotr
authors.initials: P
authors.lastname: Smolewski
authors.forename: Krystyna
authors.initials: K
authors.lastname: Fabianowska-Majewska
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology*; D001087:Arabinonucleosides / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D000077866:Clofarabine; D019175:DNA Methylation; D044127:Epigenesis, Genetic / Q000187:drug effects*; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D013454:Sulfoxides
chemical_list: D000227:Adenine Nucleotides; D001087:Arabinonucleosides; D017879:Isothiocyanates; D013454:Sulfoxides; D000077866:Clofarabine; C016766:sulforaphane