Stimulatory Release of Lipoprotein Lipase Activity with Activation of Protein Tyrosine Kinase Produced by Low Molecular Weight Dextran Sulfate in Ehrlich Ascites Tumor Cells

Abstract

Lipoprotein lipase (LPL), which is responsible for the hydrolysis of lipoprotein triacylglyceride, has been examined in Ehrlich ascites tumor cells. Low molecular weight dextran sulfate (DXS, M.W. 3.2kDa) stimulates the release of the enzyme activity from the tumor cells into the incubation medium in a time-dependent manner. The stimulatory effect of DXS was markedly decreased by incubation with protein tyrosine kinase (TK) inhibitors, such as ST 638, biochanin A and amiloride. The activity of the partially purified TK preparation from the tumor cells was found to be increased following incubation with DXS in a manner which was both time-and dose-dependent. These results suggest that the stimulatory release of LPL activity by DXS is associated with the activation of TK in the tumor cells.