PT - JOURNAL ARTICLE AU - Margaret A. Park AU - Adly Yacoub AU - Mohammed Rahmani AU - Guo Zhang AU - Lori Hart AU - Michael P. Hagan AU - Stuart K. Calderwood AU - Michael Y. Sherman AU - Costas Koumenis AU - Sarah Spiegel AU - Ching-Shih Chen AU - Martin Graf AU - David T. Curiel AU - Paul B. Fisher AU - Steven Grant AU - Paul Dent TI - OSU-03012 Stimulates PKR-Like Endoplasmic Reticulum-Dependent Increases in 70-kDa Heat Shock Protein Expression, Attenuating Its Lethal Actions in Transformed Cells AID - 10.1124/mol.107.042697 DP - 2008 Apr 01 TA - Molecular Pharmacology PG - 1168--1184 VI - 73 IP - 4 4099 - http://molpharm.aspetjournals.org/content/73/4/1168.short 4100 - http://molpharm.aspetjournals.org/content/73/4/1168.full SO - Mol Pharmacol2008 Apr 01; 73 AB - We have further defined mechanism(s) by which 2-amino-N-{4-[5-(2-phenanthrenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-phenyl}acetamide [OSU-03012 (OSU)], a derivative of the cyclooxygenase-2 (COX2) inhibitor celecoxib but lacking COX2 inhibitory activity, kills transformed cells. In cells lacking expression of protein kinase R-like endoplasmic reticulum kinase (PERK-/-), the lethality of OSU was attenuated. OSU enhanced the expression of Beclin 1 and ATG5 and cleavage of pro-caspase 4 in a PERK-dependent fashion and promoted the Beclin 1- and ATG5-dependent formation of vacuoles containing LC3, followed by a subsequent caspase 4-dependent cleavage of cathepsin B and a cathepsin B-dependent formation of low pH intracellular vesicles; cathepsin B was activated and released into the cytosol and genetic suppression of caspase 4, cathepsin B, or apoptosis-inducing factor function significantly suppressed cell killing. In parallel, OSU caused PERK-dependent increases in 70-kDa heat shock protein (HSP70) expression and decreases in 90-kDa heat shock protein (HSP90) and Grp78/BiP expression. Changes in HSP70 expression were post-transcriptional. Knock-down or small-molecule inhibition of HSP70 expression enhanced OSU toxicity, and overexpression of HSP70 suppressed OSU-induced low pH vesicle formation and lethality. Our data demonstrate that OSU-03012 causes cell killing that is dependent on PERK-induced activation of multiple toxic proteases. OSU-03012 also increased expression of HSP70 in a PERK-dependent fashion, providing support for the contention that OSU-03012-induced PERK signaling promotes both cell survival and cell death processes. The American Society for Pharmacology and Experimental Therapeutics