title: Citrus auraptene suppresses cyclin D1 and significantly delays N-methyl nitrosourea induced mammary carcinogenesis in female Sprague-Dawley rats.
abstract: BACKGROUND
  Breast cancer is a major problem in the United States leading to tens of thousands of deaths each year. Although citrus auraptene suppresses cancer in numerous rodent models, its role in breast cancer prevention previously has not been reported. Thus, our goal was to determine the anticarcinogenic effects of auraptene against breast cancer.
  
  
  METHODS
  The effects of auraptene on cell proliferation of MCF-7 and MDA-MB-231 human breast carcinoma cells in culture was assessed by measuring metabolism of a substrate to a formazan dye. Dietary effects of auraptene on tumor incidence, multiplicity and latency were studied in the N-methyl nitrosourea (MNU) induced mammary carcinogenesis model in female Sprague Dawley rats. The concentration of auraptene in rat tissues was analyzed by reverse phase HPLC. Cyclin D1 expression in MCF-7 cells and rat tumors was measured by western blot.
  
  
  RESULTS
  Auraptene (500 ppm) significantly delayed median time to tumor by 39 days compared to the MNU only group (p < 0.05, n = 24-26). Auraptene (10 microM) reduced Insulin like Growth Factor-1 (IGF-1, 10 ng/mL)-induced cyclin D1 expression by 40% in MCF-7 cells. In comparison, western blot analysis of rat mammary tumors (n = 10 per group) confirmed that auraptene (500 ppm) significantly reduced (p < 0.05) cyclin D1 expression by 49% compared to the MNU only group. Analysis of rat mammary tissue extract by HPLC with fluorescence detection indicated an average concentration (means +/- S.E.) of 1.4 +/- 0.5 microM and 1.8 +/- 0.3 microM in the normal mammary glands of the auraptene 200 ppm and 500 ppm groups, respectively. The concentration (means +/- S.E.) of auraptene in the mammary tumors of the auraptene 200 ppm group was 0.31 +/- 0.98 microM.
  
  
  CONCLUSIONS
  Overall, these observations suggest that the predominant effect of auraptene was to delay the development of tumors possibly through the suppression of cyclin D1 expression. These results point to the potential chemopreventive effects of auraptene in mammary carcinogenesis.
authors.affiliation: Department of Pharmacology, Toxicology and Neuroscience, LSUHSC-Shreveport, Louisiana, USA. hklein@lsuhsc.edu
authors.forename: Prasad
authors.initials: P
authors.lastname: Krishnan
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Yan
authors.forename: David
authors.initials: D
authors.lastname: Windler
authors.forename: Jesse
authors.initials: J
authors.lastname: Tubbs
authors.forename: Robert
authors.initials: R
authors.lastname: Grand
authors.forename: Benjamin D L
authors.initials: BD
authors.lastname: Li
authors.forename: C Marcelo
authors.initials: CM
authors.lastname: Aldaz
authors.forename: Jerry
authors.initials: J
authors.lastname: McLarty
authors.forename: Heather E
authors.initials: HE
authors.lastname: Kleiner-Hancock
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002851:Chromatography, High Pressure Liquid; D002957:Citrus / Q000378:metabolism*; D004396:Coloring Agents / Q000494:pharmacology; D003374:Coumarins / Q000494:pharmacology*; D019938:Cyclin D1 / Q000096:biosynthesis*; D005260:Female; D005562:Formazans / Q000494:pharmacology; D006801:Humans; D008770:Methylnitrosourea / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016588:Anticarcinogenic Agents; D004396:Coloring Agents; D003374:Coumarins; D005562:Formazans; D019938:Cyclin D1; D008770:Methylnitrosourea; C105832:aurapten