DIFFERENTIAL EFFECT OF BUTYRATE ON LIPIDS OF HUMAN COLON-CANCER CELLS

Recently, we demonstrated that treatment of LS174T cells with 2 mM but yrate for one day had a significant effect on the composition of cellu lar fatty acids. In an attempt to further explore this phenomenon, we investigated the effect of long-term butyrate treatment in the presenc e of different fatty acids in the medium on cellular phospholipids (PL s) and triacylglycerol (TG). Cells were supplemented with 100 muM sodi um salts of 18:2 (n-6), 20:4 (n-6), 20:5 (n-3), or 22:6 (n-3) as a fat ty acid-free-albumin complex. The molar ratio of the albumin and these long-chain fatty acids (LCFAs) was 3:1. One-half of these cultures we re supplied with 2 mM butyrate, and the pH was adjusted to 7.4. The su pplementation of the LCFAs and butyrate was maintained for eight days. The present study indicates that butyrate had a differential effect o n the fatty acid composition of PLs and TG of LS174T cells. This inclu des an increase in monounsaturates and elongation of the supplemented LCFA, and this effect was more pronounced on TG than PL fatty acids. B utyrate resulted in a significant reduction in polyunsaturated fatty a cid concentration only in PLs. In general, butyrate decreased the unsa turation index (UI) of the PLs but increased that of TG. The present s tudy also confirmed our previous observation regarding the effect of L CFAs on cellular lipids. PL and TG fatty acid chain lengths reflect th ose of supplemented fatty acids. The UI of these two lipid fractions i ncreased more with supplementation of n-3 than n-6 fatty acids. TG fat ty acids are more reflective of the ability of LS174T cells to elongat e, retroconvert, and incorporate the supplemented LCFAs than PLs. It i s concluded that butyrate, which is produced mainly in the large intes tinal tract as a result of fermentation of dietary fibers, could have a differential effect on the utilization of the LCFAs in the colon. Th e significance of this effect in cellular function of human tumor cell s is currently being investigated