Changes in lipid composition of neuroblastoma C1300 N18 cell during differentiation.

Phospholipids and cholesterol were found to be the main lipids in mature and immature neuroblastoma cells. The ratios for the total cholesterol/phospholipids in these undifferentiated and differentiated cells were 0.33 and 0.52, respectively. The ratios of 0.45 and 0.62 were obtained with corresponding plasma membrane fractions. Individual fatty acid contents in the loosely bound lipid fraction were higher than in tightly bound lipids. The total levels of saturated fatty acids increased in both of these fractions. While arachidonic acid content significantly decreased, it increased simultaneously (600%) in the free fatty acid fraction during differentiation. The amount of cholesterol esters increased three-fold as a result of maturation. For the first time it was possible to detect, in neuroblastoma cells, several lipids, namely N-acylphosphatidylethanolamine, N-acylethanolamine and semilysobisphosphatidic acid. They all changed during maturation. Total N-acylphosphatidylethanolamine content decreased by 50%, disappearing completely from membrane fractions. N-Acylethanolamine disappeared from the cell as well as from membrane fractions. On the other hand the total cellular content of semilysobisphosphatidic acid increased without any alterations in its membrane content. Functional implications of our investigations are discussed.