text: Flt3 receptor tyrosine kinase as a drug target in leukemia.
  The hematopoietic class III receptor tyrosine kinase (RTK) Flt3 (Flk2, STK1) has recently received much attention as a potential drug target. Activation of Flt3 by different types of mutations plays an important role for proliferation, resistance to apoptosis, and prevention of differentiation of leukemic blasts in acute myeloid leukemia (AML). At least one type of such mutations - an internal tandem duplication in the Flt3 juxtamembrane domain (Flt3-ITD) - has been associated with an unfavorable prognosis. Signal transduction of Flt3 involves activation of several conserved pathways, including the RAS/MAP-Kinase and the phosphoinositide-3-kinase/Akt signaling cascades. Transforming versions of Flt3 exhibit altered signaling, for example a very pronounced activation of STAT5, ultimately resulting in alternate profiles of gene expression and cell transformation. Selective inhibitors of Flt3 tyrosine kinase activity have the potential to suppress aberrant Flt3 signaling. Although highly homologous to other class III RTKs, Flt3 is resistant to the phenylaminopyrimidine STI571 (Gleevec, Imatinib), a potent inhibitor of other RTKs in the family, such as the PDGFbeta-receptor or c-Kit. STI571 binding to Flt3 is prevented by the phenylalanine 691 side-chain in the ATP binding center and mutating this site to threonine renders the corresponding Flt3 mutant sensitive to STI571. Compounds of several other structural families, including the quinoxaline AG1296, the bis(1H-2-indolyl)-1-methanone D-65476, the indolinones SU5416 and SU11248, the indolocarbazoles PKC412 and CEP-701, and the piperazonyl quinazoline CT53518, are potent inhibitors of Flt3 kinase. They exhibit different selectivity profiles, both with respect to other kinases and among wildtype Flt3 and its activated versions. These compounds hold promise as novel drugs against AML and as probes for understanding activation mechanisms and signaling pathways in the class III RTK family.
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entities.type: CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-Y GENE-N GENE-Y CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-N GENE-N GENE-N CHEMICAL GENE-N GENE-Y GENE-N GENE-N GENE-N GENE-N GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-N GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
entities.text: quinoxaline AG1296 bis(1H-2-indolyl)-1-methanone D-65476 indolinones SU5416 SU11248 indolocarbazoles PKC412 CEP-701 phenylaminopyrimidine piperazonyl quinazoline CT53518 tyrosine phosphoinositide tyrosine tyrosine class III RTKs Flt3 RTKs PDGFbeta-receptor STI571 c-Kit Flt3 Flt3 Flt3 Flt3 kinase Flt3 class III RTK Flt3 juxtamembrane domain Flt3-ITD Gleevec hematopoietic class III receptor tyrosine kinase (RTK) Flt3 Flt3 RAS MAP-Kinase phosphoinositide-3-kinase Akt Flk2 Flt3 STK1 STAT5 Imatinib Flt3 tyrosine kinase Flt3 Flt3 receptor tyrosine kinase STI571 phenylalanine ATP threonine STI571