title: CYP1A1 is overexpressed upon incubation of breast cancer cells with a polyphenolic cocoa extract.
abstract: OBJECTIVE
  To evaluate the effect of cocoa flavonoids in breast cancer cells at the molecular level, a functional genomic analysis was performed using a polyphenolic cocoa extract (PCE) in MCF-7 and SKBR3 cell lines.
  
  
  METHODS
  The expression profile of 84 genes included in the Stress & Toxicity PathwayFinder™ PCR Array was analyzed after PCE incubation for 24 h. mRNA and protein levels were analyzed by RT-PCR and western blot, respectively. Gel shift assays were used to evaluate DNA-protein complexes. Protein complexes were identified by co-immunoprecipitation. Cell viability was evaluated by MTT assays.
  
  
  RESULTS
  Upon PCE incubation, 7 genes were overexpressed and 1 underexpressed in MCF-7 cells, whereas 9 genes were overexpressed in SKBR3 cells. Among the differentially expressed genes in both cell lines, cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) was chosen for further study. CYP1A1 mRNA and protein levels and enzymatic activity increased upon PCE incubation. CYP1A1 transcriptional activation by PCE was mediated through AhR binding to XRE elements within the CYP1A1 promoter in MCF-7 cells. A protein complex including AhR and ERα was detected. The combination of PCE with tamoxifen caused a synergistic cytotoxicity in both cell lines and was due to an increase in apoptosis in MCF-7 cells.
  
  
  CONCLUSIONS
  The interaction between ERα and AhR upon incubation with PCE leads to CYP1A1 induction in breast cancer cells. The synergy between PCE and non-cytotoxic tamoxifen concentrations opens the possibility for a combination therapy based on polyphenols from cocoa that increased tamoxifen efficacy.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Carlota
authors.initials: C
authors.lastname: Oleaga
authors.forename: Miriam
authors.initials: M
authors.lastname: García
authors.forename: Anna
authors.initials: A
authors.lastname: Solé
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Ciudad
authors.forename: Maria
authors.initials: M
authors.lastname: Izquierdo-Pulido
authors.forename: Véronique
authors.initials: V
authors.lastname: Noé
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000378:metabolism; D002099:Cacao / Q000737:chemistry*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000235:genetics; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism; D020218:Response Elements / Q000187:drug effects; D012639:Seeds / Q000737:chemistry; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D051792:Basic Helix-Loop-Helix Proteins; D019363:Cytochrome P-450 CYP1A1; D047628:Estrogen Receptor alpha; D005419:Flavonoids; D010936:Plant Extracts; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; C111235:AHR protein, human; C506487:ESR1 protein, human; C569463:CYP1A1 protein, human