[Effect of conjugated linoleic acid isomers on proliferation of mammary cancer cells].

Conjugated linoleic acid (CLA) is a collective term describing a mixture of positional and geometric isomers of linoleic acid with two conjugated double bonds. Among these compounds two isomers cis9, trans11 and trans10, cis12 have received considerable attention. They are present in milk and meat fat of ruminants and the cis9, trans11 (rumenic acid) is the most abundant with lesser amounts of the trans10, cis12 isomer. A considerable number of papers suggest anticarcinogenic properties of CLA, including their ability to suppress the growth of different cancer cell lines in vitro. It was also found that these isomers may act through different mechanisms to inhibit carcinogenesis. In view of the above, the objective of this paper was evaluation of isomer-specific effects of the natural CLA isomers i.e. cis9, trans11 and trans10, cis12 on proliferation of mammary cancer cell lines. Two mammary cancer cell lines were used: MCF-7 and T47D (ATCC Collection). The cells were incubated with both CLA isomers: cis9,trans11 or trans10, cis12 within the range of 5-200 microM for 24-120 h. There were no toxic effects of any of the isomers in the range of 5-100 microM, as indicated by the Cytotoxicity Detection Kit (Roche) and cells proliferation was determined in these experimental conditions. Proliferation of cells was determined using Cell Proliferation ELISA BrdU (5' bromo-2' deoxyuridine), based on incorporation of BrdU to DNA of growing cells. The results obtained indicate that both isomers suppress the proliferation of the studied mammary cancer cell lines i.e. MCF-7 and T47D, especially when treated with the CLA isomers for 48 h or longer. Of the studied lines the strongest growth-suppressing function approximately 65% was observed for the line T47D.