title: Retinoic acid and ascorbic acid act synergistically in inhibiting human breast cancer cell proliferation.
abstract: BACKGROUND
  Breast cancer is an increasingly common malignancy. Several vitamins such as retinoic acid (RA), ascorbic acid (AA), vitamin D and vitamin E are known to prevent the development and progression of breast cancer.
  
  
  OBJECTIVE
  We sought to determine whether RA and AA together (RA+AA) acted synergistically in blocking the proliferation of human breast cancer cells. To elucidate the mechanism by which RA+AA inhibited breast carcinoma proliferation, we then evaluated the gene expression profiles of the treated and untreated cells by radioactive cDNA microarray analysis.
  
  
  METHODS
  We cultured the human breast cancer cell line MCF-7 for 3 days with 100 nM RA and/or 1 mM AA, counted the cell numbers and harvested the total RNAs for cDNA microarray analysis.
  
  
  RESULTS
  RA, AA and RA+AA reduced MCF-7 cell proliferation by 20.7%, 23.3% and 75.7% relative to the untreated cell proliferation, respectively. The synergistic ratio of RA and AA was 1.72. The MCF-7 gene expression profiles showed that 29 genes were up-regulated and 38 genes were down-regulated after RA+AA treatment. The nature of these genes suggests that the mechanism by which RA and AA act synergistically in inhibiting human breast cancer cell proliferation may involve the expression of genes that induce differentiation and block proliferation, and the up-regulation of antioxidant enzymes and proteins involved in apoptosis, cell cycle regulation and DNA repair.
  
  
  CONCLUSIONS
  Combined treatment with RA and AA inhibits the proliferation of human breast cancer cells by altering their gene expression related to antioxidation processes as well as the proliferation inhibitory pathway.
authors.affiliation: Department of Biochemistry and Molecular Biology, Korea University Medical College, Seoul 136-701, Korea.
authors.forename: Ki-Nam
authors.initials: KN
authors.lastname: Kim
authors.forename: Jae-Eun
authors.initials: JE
authors.lastname: Pie
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Park
authors.forename: Yoon-Hee
authors.initials: YH
authors.lastname: Park
authors.forename: Hye-Won
authors.initials: HW
authors.lastname: Kim
authors.forename: Meyoung-Kon
authors.initials: MK
authors.lastname: Kim
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004357:Drug Synergism; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D014212:Tretinoin / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014212:Tretinoin; D001205:Ascorbic Acid