Agbotounou W K, Umezawa K, Jacquemin-Sablon A, Pierre J
URA 147 CNRS, Institut Gustave Roussy, Villejuif, France.
Eur J Pharmacol. 1994 Sep 15;269(1):1-8. doi: 10.1016/0922-4106(94)90019-1.
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.
突变型pp60F527蛋白具有与转化活性相关的活化蛋白酪氨酸激酶（PTK）活性。我们研究了两种表皮生长因子受体（EGF-R）酪氨酸激酶抑制剂——拉文达ustin A及其衍生物之一拉文达ustin C6对pp60F527 PTK活性的抑制作用。在体外，这两种分子对于ATP结合位点均为非竞争性抑制剂，对于肽结合位点均为反竞争性抑制剂。在外源底物烯醇化酶上测定得出，拉文达ustin A抑制pp60F527激酶活性的半数抑制浓度（IC50）为18微摩尔，拉文达ustin C6为5微摩尔，表明拉文达ustin C6比拉文达ustin A更有效。拉文达ustin C6而非拉文达ustin A，抑制完整细胞中pp60F527细胞底物（与GAP相关的p190、pp125FAK和皮层肌动蛋白）的酪氨酸磷酸化。然而，这种原位抑制作用并未导致pp60F527在细胞中诱导的形态变化逆转。另一方面，拉文达ustin C6和拉文达ustin A对细胞发挥了抗增殖作用，表明抑制与该激酶相关或不相关的细胞靶点也是可能的。
