Background:

Imatinib is an inhibitor of protein-tyrosine kinase with IC50 values of 0.1, 0.1 and 0.025μM, respectively against PDGF receptor, c-Kit and Abl [1].

The type 3 group of receptor tyrosine kinases includes PDGFR, CSF-1R, Flt-3, c-Kit and so on. PDGFRs are found in normal tissues, cells as well as some tumors. It is associated with several nonmalignant proliferative diseases. In vitro assays show that Imatinib can inhibit both PDGF-AA and PDGF-BB stimulated PDGF receptor phosphorylation. Imatinib is also found to inhibit the phosphorylation of c-Kit, another kinase which mediates the growth of a number of tumors. Imatinib inhibits the phosphorylation of these kinases without effecting the expression of them. Some other kinases of the type 3 group (such as Fms and Flt-3) can’t be inhibited by Imatinib, suggesting a selectivity of Imatinib. In addition, Imatinib is shown to significantly inhibit the Bcr-Abl tyrosine kinase both in cell-based assay and in vitro kinase assay. Moreover, as a downstream pathway of PDGF-mediated signals, MAP kinase activation can also be effected in rat A10 smooth muscle cells [1].

参考文献:
[1] Elisabeth Buchdunger, Catherine L. Cioffi, Norman Law, David Stover, Sayuri Ohno-Jones, Brian J. Druker And Nicholas B. Lydon. Abl protein-tyrosine kinase inhibitor sti571 inhibits in vitro signal transduction mediated by c-kit and platelet-derived growth factor receptors. The journal of pharmacology and experimental therapeutics. 2000, 295(1): 139-145.