title: Conjugated docosahexaenoic acid suppresses KPL-1 human breast cancer cell growth in vitro and in vivo: potential mechanisms of action.
abstract: BACKGROUND
  The present study was conducted to examine the effect of conjugated docosahexaenoic acid (CDHA) on cell growth, cell cycle progression, mode of cell death, and expression of cell cycle regulatory and/or apoptosis-related proteins in KPL-1 human breast cancer cell line. This effect of CDHA was compared with that of docosahexaenoic acid (DHA).
  
  
  METHODS
  KPL-1 cell growth was assessed by colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay; cell cycle progression and mode of cell death were examined by flow cytometry; and levels of expression of p53, p21Cip1/Waf1, cyclin D1, Bax, and Bcl-2 proteins were examined by Western blotting analysis. In vivo tumor growth was examined by injecting KPL-1 cells subcutaneously into the area of the right thoracic mammary fat pad of female athymic mice fed a CDHA diet.
  
  
  RESULTS
  CDHA inhibited KPL-1 cells more effectively than did DHA (50% inhibitory concentration for 72 hours: 97 micromol/l and 270 micromol/l, respectively). With both CDHA and DHA growth inhibition was due to apoptosis, as indicated by the appearance of a sub-G1 fraction. The apoptosis cascade involved downregulation of Bcl-2 protein; Bax expression was unchanged. Cell cycle progression was due to G0/G1 arrest, which involved increased expression of p53 and p21Cip1/Waf1, and decreased expression of cyclin D1. CDHA modulated cell cycle regulatory proteins and apoptosis-related proteins in a manner similar to that of parent DHA. In the athymic mouse system 1.0% dietary CDHA, but not 0.2%, significantly suppressed growth of KPL-1 tumor cells; CDHA tended to decrease regional lymph node metastasis in a dose dependent manner.
  
  
  CONCLUSIONS
  CDHA inhibited growth of KPL-1 human breast cancer cells in vitro more effectively than did DHA. The mechanisms of action involved modulation of apoptosis cascade and cell cycle progression. Dietary CDHA at 1.0% suppressed KPL-1 cell growth in the athymic mouse system.
authors.affiliation: Department of Pathology II, Kansai Medical University, Moriguchi, Osaka, Japan. tsujita@takii.kmu.ac.jp
authors.forename: Miki
authors.initials: M
authors.lastname: Tsujita-Kyutoku
authors.forename: Takashi
authors.initials: T
authors.lastname: Yuri
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Danbara
authors.forename: Hideto
authors.initials: H
authors.lastname: Senzaki
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kiyozuka
authors.forename: Norihisa
authors.initials: N
authors.lastname: Uehara
authors.forename: Hideho
authors.initials: H
authors.lastname: Takada
authors.forename: Takahiko
authors.initials: T
authors.lastname: Hada
authors.forename: Teruo
authors.initials: T
authors.lastname: Miyazawa
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Airo
authors.initials: A
authors.lastname: Tsubura
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D004281:Docosahexaenoic Acids / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation / Q000379:methods; D014407:Tumor Cells, Cultured
chemical_list: D018797:Cell Cycle Proteins; D004281:Docosahexaenoic Acids