title: Influence of in vitro supplementation with lipids from conventional and Alpine milk on fatty acid distribution and cell growth of HT-29 cells.
abstract: BACKGROUND
  To date, the influence of milk and dairy products on carcinogenesis remains controversial. However, lipids of ruminant origin such as conjugated linoleic acids (CLA) are known to exhibit beneficial effects in vitro and in vivo. The aim of the present study was to determine the influence of milk lipids of different origin and varying quality presenting as free fatty acid (FFA) solutions on cellular fatty acid distribution, cellular viability, and growth of human colon adenocarcinoma cells (HT-29).
  
  
  METHODS
  FAME of conventional and Alpine milk lipids (MLcon, MLalp) and cells treated with FFA derivatives of milk lipids were analyzed by means of GC-FID and Ag+-HPLC. Cellular viability and growth of the cells were determined by means of CellTiter-Blue®-assay and DAPI-assay (4',6-diamidino-2-phenylindole dihydrochloride), respectively.
  
  
  RESULTS
  Supplementation with milk lipids significantly decreased viability and growth of HT-29 cells in a dose- and time-dependent manner. MLalp showed a lower SFA/MUFA ratio, a 8 fold increased CLA content, and different CLA profile compared to MLcon but did not demonstrate additional growth-inhibitory effects. In addition, total concentration and fatty acid distribution of cellular lipids were altered. In particular, treatment of the cells yielded highest amounts of two types of milk specific major fatty acids (μg FA/mg cellular protein) after 8 h of incubation compared to 24 h; 200 μM of MLcon (C16:0, 206 ± 43), 200 μM of MLalp (C18:1 c9, (223 ± 19). Vaccenic acid (C18:1 t11) contained in milk lipids was converted to c9,t11-CLA in HT-29 cells. Notably, the ratio of t11,c13-CLA/t7,c9-CLA, a criterion for pasture feeding of the cows, was significantly changed after incubation for 8 h with lipids from MLalp (3.6 - 4.8), compared to lipids from MLcon (0.3 - 0.6).
  
  
  CONCLUSIONS
  Natural lipids from conventional and Alpine milk showed similar growth inhibitory effects. However, different changes in cellular lipid composition suggested a milk lipid-depending influence on cell sensitivity. It is expected that similar changes may also be evident in other cell lines. To our knowledge, this is the first study showing a varied impact of complex milk lipids on fatty acid distribution in a colon cancer cell line.
authors.affiliation: Institute of Nutrition, Dept. of Nutritional Physiology, Friedrich-Schiller-University, Dornburger Strasse 24, Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Degen
authors.forename: Alfred
authors.initials: A
authors.lastname: Lochner
authors.forename: Sylvia
authors.initials: S
authors.lastname: Keller
authors.forename: Katrin
authors.initials: K
authors.lastname: Kuhnt
authors.forename: Sven
authors.initials: S
authors.lastname: Dänicke
authors.forename: Gerhard
authors.initials: G
authors.lastname: Jahreis
mesh_terms: D000818:Animals; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D044243:Linoleic Acids, Conjugated / Q000378:metabolism / Q000494:pharmacology; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry / Q000494:pharmacology*; D008892:Milk / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D008055:Lipids