Stimulatory release of hepatic lipase activity from liver by epidermal growth factor

We have found that release of hepatic lipase activity is stimulated from liver slices by epidermal growth factor (EGF) into the medium in a time-dependent manner. This novel effect of EGF was markedly decreased by various tyrosine kinase inhibitors, such as alpha-cyano-3-ethoxy-4-hydroxy-5-phenyl-thiomethyl cinnamamide, amiloride and biochanin A. The stimulation by EGF was also suppressed, however, by dibutyryl cyclic adenosine monophosphate, and 3-isobutyl-1-methylxanthine, a cyclic nucleotide dependent phosphodiesterase inhibitor. These findings show that the stimulatory release of the enzyme activity by EGF is associated with the activation of tyrosine kinase activity and with the intracellular cyclic adenosine monophosphate level.