Abl Protein-Tyrosine Kinase Inhibitor STI571 Inhibits In Vitro Signal Transduction Mediated by c-Kit and Platelet-Derived Growth Factor Receptors.

STI571 (formerly known as CGP 57148B) is a protein-tyrosine kinase inhibitor that is currently in clinical trials for the treatment of chronic myelogenous leukemia. STI571 selectively inhibits the Abl and platelet-derived growth factor (PDGF) receptor tyrosine kinases in vitro and blocks cellular proliferation and tumor growth of Bcr-abl- or v-abl-expressing cells. We have further investigated the profile of STI571 against related recep- tor tyrosine kinases. STI571 was found to potently inhibit the kinase activity of the ��- and ��-PDGF receptors and the receptor for stem cell factor, but not the closely related c-Fms, Flt-3, Kdr, Flt-1, and Tek tyrosine kinases. Additionally, no inhibition of c-Met or nonreceptor tyrosine kinases such as Src and Jak-2 has been observed. In cell-based assays, STI571 selectively inhibited PDGF and stem cell factor-mediated cellular signal- ing, including ligand-stimulated receptor autophosphorylation, inositol phosphate formation, and mitogen-activated protein kinase activation and proliferation. These results expand the profile of STI571 and suggest that in addition to chronic my- elogenous leukemia, STI571 may have clinical potential in the treatment of diseases that involve abnormal activation of c-Kit or PDGF receptor tyrosine kinases.

Xanya Sofra Weiss

Xanya Sofra Weiss