Cellular uptake and retention measurements of alkylphosphocholines in the SK-BR-3 breast cancer and Molt-4 leukemia cell line using capillary gas chromatography

The determination of cellular content of octadecylphosphocholine (D-19391) and hexadecylphosphocholine (HePC, D-18506), two anticancer agents of the alkylphosphocholine group, using capillary gas chromatography is described. The compounds' cytotoxicity was first determined by the MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium] assay, being indicative for the concentration used in the uptake and retention measurements. D-19391 was added to the SK-BR-3 breast cancer cell line and HePC to the Molt-4 leukemia cell line in concentrations of, respectively, 18.6 and 15.0 mu M, during a 36-h incubation period at 37 degrees C, 5% CO2. HePC uptake in the leukemia cells was followed by a 24-h reversibility test in drug-free medium. Subsequently, sample clean-up was performed on a weak cation-exchange column. For the quantitative analysis, HePC was used as internal standard for the D-19391 measurements and vice versa. Derivatization of the samples with trimethylsilylbromide was followed by capillary gas chromatographic analysis. From these data we conclude that our uptake results are quite similar with those of a previous study of HePC cellular uptake in the more resistant Caco-2T colon cancer cell line. Without having investigated the mechanism that underlies the cellular uptake results obtained, our study points to no direct correlation between the compounds' cellular uptake and their cytotoxic effects.