Kinase c-Kit

Nocka, K., Majumder, S., Chabot, B., Ray, P., Cervone, M., Bernstein, A., and Besmer, P. (1989). Expression of the c-kit gene products in known cellular targets of W mutant mice-evidence for an impaired c-kit kinase in mutant mice. Genes Dev. 3 816-826. 

Figure 5. An example of intra-family target hopping within kinases. According to SiteSorter, Braf kinase, the primary target for the clinical compound BAY 43-9006, is one of the 10 most similar kinases to c-Kit, which has also been shown to bind BAY 43-9006 with sub-micromolar affinity (60% of the binding site residues are consen/ed and colored blue non-consen/ed positions are colored yellow). This cross-reactivity cannot be predicted based on the sequence similarity of the Braf and c-Kit kinase domains, since approximately one-sixth of the human kinome is more sequence similar to Braf than c-KiL...

Fernandez A, Sanguino A, Peng Z et al (2007) An anticancer C-kit kinase inhibitor is reengineered to make it more active and less cardiotoxic. J Clin Invest 117 4044-4054... 

Fig. 8.7 (a) In vitro phosphorylation inhibition assay for Abl enzyme in the presence of WBZ 4 (squares) or imatinib (triangles). Active recombinant Abl enzyme (1 (Jig/ml) and its substrate (Abl-tide, 1 p.g/ml) were incubated for 1 h at 37°C in the presence of various WBZ 4 or imatinib concentrations. ATP (100 nM) was added to the reaction mixture. Phosphorylation of Abl-tide peptide was detected by incubation in consecutive order with antirabbit phospho-Abl-tide antibody and antirabbit horseradish peroxidase (HRP) antibody. Phosphorylation of the substrate was quantified as absorbance units (AU) by spectrophotometry at 450 nm. Values obtained with the enzyme without the inhibitors (WBZ 4 or imatinib) were assumed to be 100% phosphorylation and were compared to the values obtained with the addition of the inhibitors, (b) In vitro phosphorylation inhibition assay for C-Kit in the presence of WBZ 4 (squares) or imatinib (triangles). Active recombinant C-Kit kinase (25 ng/ml) and its substrate poly (Glu4-Tyr, 150 nM) were... 

Fig. 8.9 (a) Western blot of C-Kit inhibition. WBZ 4 inhibits phosphorylation of C-Kit kinase in ST-882 GIST cells. Gel bands from the western blot assays of C-Kit and its phosphorylated (P) form in GIST cells treated with WBZ 4 and imatinib. The fi-actin assay was adopted as control, (b) Western blot of Bcr-Abl inhibition. Phosphorylation of Bcr-Abl kinase is not significantly inhibited by WBZ 4 in K562 CML cells. Electrophoretic gel bands for western blots for Bcr-Abl kinase and its phosphorylated (P) form in CML cells treated with WBZ 4 and imatinib. Reprinted from the [14], copyright 2007 with permission from the American Society for Clinical Investigation... 

Fig. 13.2 Imatinib wrapping modification engineered to overcome drug resistance in the C-Kit kinase. This resistance is promoted by the somatic mutation Asp816Val. The mutation induces the dehydron Phe811-Ala814 in the activation loop which in turn can be targeted or wrapped by suitably modifying imatinib at the position highlighted by the rectangle [3]...

Figure 5.3 Sequences of important regions of c-Kit kinase, highlighting sites of resistance mutations identified from clinical tumor samples. Important mutations include V654A, D816 H-V, D820G, N822K, and Y823D. The sequence of Abl kinase from Figure 5.2 is included for reference.

Sorafenib/BAY 43-9006 RAF, VEGFR, PDGFR, c-Kit Kinase inhibitor Phase III, Kidney Cancer... 

STI 571 <322> (<322>, a phenylaminopyrimidine derivative, a potent inhibitor of the Abl tyrosine kinase, PDGFR kinases and c-Kit tyrosine kinases [705] <322> designed to inhibit ABL and BCR-ABL tyrosine kinases, inhibition through competitive ATP-binding pocket interactions [706] <322> use un second-line therapy of small-cell lung cancer, inhibits c-kit kinase, resulting in an metabolic change of tumor cells [706]) [705, 706]... 

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