title: Computer-based identification of a novel LIMK1/2 inhibitor that synergizes with salirasib to destabilize the actin cytoskeleton.
abstract: Neurofibromin regulates cell motility via three distinct GTPase pathways acting through two different domains, the Ras GTPase-activating protein-related domain (GRD) and the pre-GRD domain. First, the GRD domain inhibits Ras-dependent changes in cell motility through the mitogen activated protein cascade. Second, it also regulates Rho-dependent (Ras-independent) changes by activating LIM kinase 2 (LIMK2), an enzyme that phosphorylates and inactivates cofilin (an actin-depolymerizing factor). Third, the pre-GRD domain acts through the Rac1 GTPase, that activate the P21 activated kinase 1 (PAK1)-LIMK1-cofilin pathway. We employed molecular modeling to identify a novel inhibitor of LIMK1/2. The active sites of an ephrin-A receptor (EphA3) and LIMK2 showed marked similarity (60%). On testing a known inhibitor of EphA3, we found that it fits to the LIMK1/2-ATP binding site and to the latter's substrate-binding pockets. We identified a similar compound, T56-LIMKi, and found that it inhibits LIMK1/2 kinase activities. It blocked the phosphorylation of cofilin which led to actin severance and inhibition of tumor cell migration, tumor cell growth, and anchorage-independent colony formation in soft agar. Because modulation of LIMK by neurofibromin is not affected by the Ras inhibitor Salirasib, we examined the combined effect of Salirasib and T56-LIMKi each of which can affect cell motility by a distinct pathway. We found that their combined action on cell proliferation and stress-fiber formation in neurofibromin-deficient cells was synergistic. We suggest that this drug combination may be developed for treatment of neurofibromatosis and cancer.
authors: The Blavatnik School of Computer Science, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel Aviv, Israel.
authors: Efrat
authors: E
authors: Mashiach-Farkash
authors: Roni
authors: R
authors: Rak
authors: Galit
authors: G
authors: Elad-Sfadia
authors: Roni
authors: R
authors: Haklai
authors: Shmuel
authors: S
authors: Carmeli
authors: Yoel
authors: Y
authors: Kloog
authors: Haim J
authors: HJ
authors: Wolfson
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000494:pharmacology*; D001549:Benzamides / Q000008:administration & dosage / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D005204:Farnesol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D007555:Isoxazoles / Q000008:administration & dosage / Q000494:pharmacology*; D054461:Lim Kinases / Q000037:antagonists & inhibitors*; D051379:Mice; D018345:Mice, Knockout; D025542:Neurofibromin 1 / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D012459:Salicylates / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: C000597301:3-methyl-N-(3-((3-(trifluoromethyl)phenyl)carbamoyl)phenyl)isoxazole-5-carboxamide; D001549:Benzamides; D007555:Isoxazoles; D025542:Neurofibromin 1; D047428:Protein Kinase Inhibitors; D012459:Salicylates; C093323:farnesylthiosalicylic acid; D005204:Farnesol; C515892:LIMK1 protein, human; C102895:LIMK2 protein, human; D054461:Lim Kinases; C095325:Limk2 protein, mouse