Differences in Lipid Composition of Doxorubicin-sensitive and -resistant P388 Cells

An anthracycline-resistant subline of P388 murine leukemia cells, P388/ADR, has been shown to have an altered total lipid content and composition when compared to the parent line. When specific lipids of the cell lines are compared, it is found that P388/ADR cells contain approximately 3.6 times the amount of triglycerides as P388 cells. Although no differences are noted in the amounts of unesterified cholesterol or total phospholipids in the two cell lines, they do differ in specific phospholipid patterns. P388/ADR cells contain relatively less phosphatidylcholine and more sphingomyelin than drug-sensitive cells. No differences are observed in the content of phosphatidylethanolamine and cardiolipin. The difference in phosphatidylcholine/sphingomyelin ratio (5.57 for ADR-sensitive cells and 3.28 for ADR-resistant cells) may account for the previously observed difference in plasma membrane lipid structural order between these cell lines. Measurements of the relative activity of phosphocholine transferase in the two lines, using the rate of incorporation of 3H-choline into phosphatidylcholine, indicate that lower phosphocholine transferase activity in P388/ADR cells may account for the observed changes in cellular lipid and phospholipid composition.