Inhibition by two lavendustins of the tyrosine kinase activity of pp60F527 in vitro and in intact cells.
The mutant pp60F527 protein possesses an activated protein-tyrosine kinase (PTK) activity correlated with a transforming activity. We have studied the inhibition of the pp60F527 PTK activity by two EGF-R tyrosine kinase inhibitors, lavendustin A and one of its derivatives, lavendustin C6. In vitro, both molecules were non-competitive inhibitors for the ATP binding site and uncompetitive inhibitors for the peptide binding site. The determined IC50S of the inhibition of pp60F527 kinase activity were 18 microM for lavendustin A and 5 microM for lavendustin C6, as determined on the exogenous substrate enolase, showing that lavendustin C6 was more potent than lavendustin A. Lavendustin C6, but not lavendustin A, inhibited the tyrosine phosphorylation of pp60F527 cellular substrates (the GAP-associated p190, pp125FAK and cortactin) in intact cells. However, this in situ inhibitory effect did not result in a reversion of the morphological changes induced by pp60F527 in cells. On the other hand, lavendustin C6 and lavendustin A exerted antiproliferative effects on cells, suggesting that inhibition of cellular targets related or not to the kinase was also possible.
Agbotounou
W K
WK
URA 147 CNRS, Institut Gustave Roussy, Villejuif, France.
Umezawa
K
K
Jacquemin-Sablon
A
A
Pierre
J
J
D016475:3T3 Cells / Q000166:cytology / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation / Q000235:genetics; D010636:Phenols / Q000378:metabolism / Q000494:pharmacology*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D015682:Retroviridae Proteins, Oncogenic / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D010636:Phenols; D015682:Retroviridae Proteins, Oncogenic; C080022:lavendustin C6; C062898:lavendustin A; D000255:Adenosine Triphosphate; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D010751:Phosphopyruvate Hydratase