Volume 90, Issue 5, November (2003), pp. 877-885 © The Author 2003
doi:10.1079/BJN2003978

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Conjugated linoleic acid (CLA)-enriched milk fat inhibits growth and modulates CLA-responsive biomarkers in MCF-7 and SW480 human cancer cell lines

Áine Miller¹, Catherine Stanton², John Murphy³, Rosaleen Devery^4
1School of Biotechnology, Dublin City University, Dublin 9, , Republic of Ireland
²Teagasc Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Republic of Ireland
³Teagasc Dairy Production Department, Moorepark, Fermoy, Co. Cork, Republic of Ireland
⁴School of Biotechnology, National Institute of Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Republic of Ireland

 (Received 17 September 2002–Revised 24 June 2003–Accepted 14 July 2003)

Milk enriched in conjugated linoleic acid (CLA) was obtained from cows on pasture supplemented with full-fat rapeseeds (FFR; 2·26 g cis 9, trans 11 (c9, t11)-CLA/100 g fatty acid methyl esters) and full-fat soyabeans (1·83 g c9, t11-CLA/100 g fatty acid methyl esters). A control milk fat (1·69 g c9, t11-CLA/100 g fatty acid methyl esters) was obtained from cows fed on pasture only. The present study assessed the potency of the CLA-enriched milk fats to modulate biomarkers that had previously been observed to respond to c9, t11-CLA in the MCF-7 and SW480 cell lines. Cell numbers decreased (P<0·05) by up to 61 and 58 % following the incubation of MCF-7 and SW480 cells, respectively, for 4 d with milk fats (yielding CLA concentrations between 60·2 and 80·6 μM). The FFR milk fat, containing the highest CLA content, increased (P<0·05) [¹⁴C]arachidonic acid (AA) uptake into the monoacylglycerol fraction of MCF-7 and SW480 cells while it decreased (P<0·05) uptake into the phospholipid fraction of the latter. This milk fat also decreased (P<0·05) [¹⁴C]AA conversion to prostaglandin (PG) E₂ while increasing conversion to PGF₂α in both cell lines. All milk-fat samples increased (P<0·05) lipid peroxidation as measured by 8-epi-PGF₂α in both cell lines. In SW480 cells the milk-fat samples decreased (P<0·05) bcl-2 and cytosolic glutathione levels while increasing (P<0·05) membrane-associated annexin V levels. All milk-fat samples decreased (P<0·05) the expression of ras in SW480 cells. These data suggest that milk-fat CLA was effective at modulating synthetic CLA-responsive biomarkers.

Keywords:
Milk fat, Conjugated linoleic acid, Eicosanoids, Apoptosis

Abbreviations:
AA, arachidonic acid, c9, t11, cis 9, trans 11, CLA, conjugated linoleic acid, FFR, full-fat rapeseed, FFS, full-fat soyabean, GSH, reduced glutathione, LA, linoleic acid, MG, monoacylglycerol, PBST, PBS containing 0·1 % (v/v) Tween 20, PG, prostaglandin, TVA, trans-vaccenic acid