title: Trans-10,cis-12, not cis-9,trans-11, conjugated linoleic acid decreases ErbB3 expression in HT-29 human colon cancer cells.
abstract: OBJECTIVE
  To examine whether trans-10,cis-12 CLA (t10c12) or cis-9,trans-11 CLA (c9t11) inhibits heregulin (HRG)-beta-stimulated cell growth and HRG-beta-ErbB3 signaling in HT-29 cells.
  
  
  METHODS
  We cultured HT-29 cells in the absence or presence of the CLA isomers and/or the ErbB3 ligand HRG-beta. MTT assay, [3H]thymidine incorporation, Annexin V staining, RT-PCR, Western blotting, immunoprecipitation, and in vitro kinase assay were performed.
  
  
  RESULTS
  HRG-beta increased cell growth, but did not prevent t10c12-induced growth inhibition. T10c12 inhibited DNA synthesis and induced apoptosis of HT-29 cells, whereas c9t11 had no effect. T10c12 decreased the levels of ErbB1, ErbB2, and ErbB3 proteins and transcripts in a dose-dependent manner, whereas c9t11 had no effect. Immunoprecipitation/Western blot studies revealed that t10c12 inhibited HRG-beta-stimulated phosphorylation of ErbB3, recruitment of the p85 subunit of phosphoinositide 3-kinase (PI3K) to ErbB3, ErbB3-associated PI3K activities, and phosphorylation of Akt. However, c9t11 had no effect on phospho Akt levels. Neither t10c12 nor c9t11 had any effect on HRG-beta-induced phosphorylation of ERK-1/2.
  
  
  CONCLUSIONS
  These results indicate that the inhibition of HT-29 cell growth by t10c12 may be induced via its modulation of ErbB3 signaling leading to inhibition of Akt activation.
authors.affiliation: Department of Food Science and Nutrition, Hallym University, 1 Okchon Dong, Chuncheon 200-702, Korea.
authors.forename: Han Jin
authors.initials: HJ
authors.lastname: Cho
authors.forename: Woo Kyoung
authors.initials: WK
authors.lastname: Kim
authors.forename: Jae In
authors.initials: JI
authors.lastname: Jung
authors.forename: Eun Ji
authors.initials: EJ
authors.lastname: Kim
authors.forename: Soon Sung
authors.initials: SS
authors.lastname: Lim
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Kwon
authors.forename: Jung Han Yoon
authors.initials: JH
authors.lastname: Park
mesh_terms: D002455:Cell Division / Q000187:drug effects; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D019073:HT29 Cells; D006801:Humans; D044243:Linoleic Acids, Conjugated / Q000737:chemistry* / Q000494:pharmacology*; D020893:Receptor, ErbB-3 / Q000037:antagonists & inhibitors*; D013237:Stereoisomerism
chemical_list: D044243:Linoleic Acids, Conjugated; D020893:Receptor, ErbB-3