Ethanol modulates epidermal growth factor-stimulated tyrosine kinase and phosphorylation of PLC-gamma 1.
A431 cells have an abundance of Epidermal Growth Factor (EGF) receptors which possess intrinsic tyrosine kinase activity. Treatment of membranes isolated from A431 cells with EGF caused a 2-3 fold increase in phosphorylation of a synthetic peptide (Arg-Arg-Leu-Ile-Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Gly) which is a substrate for tyrosine kinase. Treatment of these membranes with 0.1 to 100 mM ethanol altered basal tyrosine kinase activity in a biphasic manner; increase at 10 mM and decrease at 100 mM ethanol. The treatment of the membranes with the same concentrations of ethanol also altered EGF's ability to stimulate tyrosine kinase activity: increase at 0.1 mM ethanol and decrease at 10 mM. Strikingly, EGF-stimulated tyrosine kinase was more sensitive to ethanol than the basal activity. Experiments with other alcohols showed a relationship between chain length and the inhibitory ability of the alcohol. These data demonstrate a biochemical effect of low concentrations of ethanol on tyrosine kinase. Interestingly, ethanol treatment of A431 cells inhibited EGF-stimulated phosphorylation of PLC-gamma 1 which is a substrate for EGF receptor tyrosine kinase. It is concluded that ethanol at low concentrations has significant modulatory effect on basal and EGF-stimulated tyrosine kinase, as well as PLC-gamma 1 phosphorylation.
Thurston
A W
AW
Department of Pharmacology, School of Medicine, University of Missouri, Columbia 65212.
Shukla
S D
SD
D000595:Amino Acid Sequence; D002294:Carcinoma, Squamous Cell; D002462:Cell Membrane / Q000201:enzymology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000302:isolation & purification / Q000378:metabolism*
D007527:Isoenzymes; D009842:Oligopeptides; D000431:Ethanol; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases