Accumulation of triacylglycerol in tissue culture cells derived from human embryonic lung (L-132 cells) on administration of di-n-butyl phthalate.

Effect of di-n-butyl phthalate on the cultured epithelium-like cells derived from human embryo lung (L-132 cells) was investigated. Suppression of cell growth, morphological change to jagged shapes of the cells, and the appearance of many lipid droplets in the cytoplasm of the cells occurred by the addition of dibutyl phthalate in the culture medium (40 micrograms/ml). Remarkable amount of triacylglycerol accumulated (7-10 fold) in the cytosol of the cells cultured in the medium containing dibutyl phthalate (40 micrograms/ml). The level of cholesterol and protein did not change and phospholipid decreased a little in its content. It was confirmed that short term-labeling of cellular triacylglycerol with [U-14C]glucose or [1-14C]oleic acid was remarkably stimulated in the phthalate ester-treated cells, and the incorporation of the radioactivity into phospholipid fraction decreased simultaneously. Decrease in the disappearance rate of the radioactivity of short term-labeled triacyglycerol was also observed. The above results indicate a possibility that the accumulation of triacylglycerol by the phthalate ester was due to the stimulation of its synthesis mainly through de novo pathway with the concomitant depression of its degradation. The accumulation of the cellular triacylglycerol was reversibly dissolved by the removal of dibutyl phthalate from the culture medium.