title: The Tyr-kinase inhibitor AG879, that blocks the ETK-PAK1 interaction, suppresses the RAS-induced PAK1 activation and malignant transformation.
abstract: AG 879 has been widely used as a Tyr kinase inhibitor specific for ErbB2 and FLK-1, a VEGF receptor. The IC(50) for both ErbB2 and FLK-1 is around 1 microM. AG 879, in combination of PP1 (an inhibitor specific for Src kinase family), suppresses almost completely the growth of RAS-induced sarcomas in nude mice. In this paper we demonstrate that AG 879 even at 10 nM blocks the specific interaction between the Tyr-kinase ETK and PAK1 (a CDC42/ Rac-dependent Ser/Thr kinase) in cell culture. This interaction is essential for both the RAS-induced PAK1 activation and transformation of NIH 3T3 fibroblasts. However, AG 879 at 10 nM does not inhibit either the purified ETK or PAK1 directly in vitro, suggesting that this drug blocks the ETK-PAK1 pathway by targeting a highly sensitive kinase upstream of ETK. Although the Tyr-kinases Src and FAK are known to activate ETK directly, Src is insensitive to AG 879, and FAK is inhibited by 100 nM AG 879, but not by 10 nM AG879. The structure-function relationship analysis of AG 879 derivatives has revealed that both thio and tert-butyl groups of AG 879, but not (thio) amide group, are essential for its biological function (blocking the ETK-PAK1 pathway), suggesting that through the (thio) amide group, AG 879 can be covalently linked to agarose beads to form a bioactive affinity ligand useful for identifying the primary target of this drug.
authors.affiliation: Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville/Melbourne, Australia.
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Hirokawa
authors.forename: Aviv
authors.initials: A
authors.lastname: Gazit
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mano
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawakami
authors.lastname: Kawakami
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Hsieh
authors.forename: Hsing-Jien
authors.initials: HJ
authors.lastname: Kung
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lessene
authors.forename: Jonathan
authors.initials: J
authors.lastname: Baell
authors.forename: Alexander
authors.initials: A
authors.lastname: Levitzki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maruta
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D004789:Enzyme Activation; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology*; D054462:p21-Activated Kinases; D018631:ras Proteins / Q000037:antagonists & inhibitors
chemical_list: C081020:AG-879; D011994:Recombinant Proteins; D020032:Tyrphostins; C492366:Bmx protein, mouse; D011505:Protein-Tyrosine Kinases; C515905:Pak1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D018631:ras Proteins