2-Amino-N-{4-[5-(2-phenanthrenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] -phenyl} acetamide (OSU-03012), a celecoxib derivative, directly targets p21-activated kinase

Leonardo M. Porchia, Marcy Guerra, Yu Chieh Wang, Yunlong Zhang, Allan V. Espinosa, Motoo Shinohara, Samuel K. Kulp, Lawrence S. Kirschner, Motoyasu Saji, Ching Shih Chen, Matthew D. Ringel

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70 Scopus citations


p21-Activated kinases (PAKs) are regulators of cell motility and proliferation. PAK activity is regulated in part by phosphoinositide-dependent kinase 1 (PDK1). We hypothesized that reduced PAK activity was involved in the effects of 2-amino-N-{4-[5-(2-phenanthrenyl)-3-(trifluoromethyl)-1H-pyrazol-1- yl]-phenyl} acetamide (OSU-03012), a previously characterized PDK1 inhibitor derived from celecoxib. In three human thyroid cancer cell lines, OSU-03012 inhibited cell proliferation with reduced AKT phosphorylation by PDK1. OSU-03012 unexpectedly inhibited PAK phosphorylation at lower concentrations than PDK1-dependent AKT phosphorylation in two of the three lines. In cell-free kinase assays, OSU-03012 was shown to inhibit PAK activity and compete with ATP binding. In addition, computer modeling predicted a docking site for OSU-03012 in the ATP binding motif of PAK1. Finally, overexpression of constitutively activated PAK1 partially rescued the ability of motile NPA thyroid cancer cells to migrate during OSU-03012 treatment, suggesting that inhibition of PAK may be involved in the cellular effects of OSU-03012 in these cells. In summary, OSU-03012 is a direct inhibitor of PAK, and inhibition of PAK, either directly or indirectly, may be involved in its biological effects in vitro.

Original languageEnglish
Pages (from-to)1124-1131
Number of pages8
JournalMolecular Pharmacology
Issue number5
StatePublished - Nov 2007


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