Effects of specific fatty acids on sphinganine ± GT-11-induced dihydroceramides and cytotoxicity.

<p><i>A</i>, <i>B</i>) Effects on dihydroceramides. CCRF-CEM cells were treated with (<i>A</i>) sphinganine (1 µM), or (<i>B</i>) sphinganine (1 µM) + GT-11 (0.5 µM), and supplemented with the indicated fatty acids (5 µM) for six hours, followed by sphingolipid assay. To evaluate the effects resulting from addition of each fatty acid, data for (<i>A</i>) and (<i>B</i>) were normalized either to cells that received sphinganine-only with no fatty acid supplementation (<i>A</i>), or to sphinganine + GT-11 without fatty acid (<i>B</i>), and plotted as fold change (Z-axis). Fatty acids are identified by x:y, where x is the number of carbons and y is the number of double bonds in the fatty acid chain (Y-axis). Significant (<i>P</i> ≤ 0.05) differences from sphinganine-only are indicated by asterisks (*). <i>C</i>) Effects on cytotoxicity. CCRF-CEM cells were treated with sphinganine-only (0-4 µM), or sphinganine (0-4 µM) + GT-11 (0.5 µM), supplemented with the indicated fatty acids (5 µM). Cytotoxicity assayed by DIMSCAN cytotoxicity assay at +48 hours. Data were normalized to control and plotted as survival fraction (Y-axis). Error bar, SEM. Data, grouped by sphinganine dose, were analyzed by one-way ANOVA.