title: OSU-03012 suppresses GRP78/BiP expression that causes PERK-dependent increases in tumor cell killing.
abstract: We have further defined mechanism(s) by which the drug OSU-03012 (OSU) kills tumor cells. OSU lethality was suppressed by knock down of PERK and enhanced by knock down of ATF6 and IRE1α. OSU treatment suppressed expression of the chaperone, BiP/GRP78, and did so through reduced stability of the protein. Knock down of BiP/GRP78 further enhanced OSU lethality. Overexpression of BiP/GRP78 abolished OSU toxicity. Pre-treatment of cells with OSU enhanced radiosensitivity to a greater extent than concomitant or sequential drug treatment with radiation exposure. Expression of a mutant active p110 PI3K, or mutant active forms of the EGFR in GBM cells did not differentially suppress OSU killing. In contrast loss of PTEN function reduced OSU lethality, without altering AKT, p70 S6K or mTOR activity, or the drug's ability to radiosensitize GBM cells. Knock down of PTEN protected cells from OSU and radiation treatment whereas re-expression of PTEN facilitated drug lethality and radiosensitization. In a dose-dependent fashion OSU prolonged the survival of mice carrying GBM tumors and interacted with radiotherapy to further prolong survival. Collectively, our data show that reduced BiP/GRP78 levels play a key role in OSU-3012 toxicity in GBM cells, and that this drug has in vivo activity against an invasive primary human GBM isolate.
authors.affiliation: Department of Neurosurgery, Virginia Commonwealth University, Richmond, USA.
authors.forename: Laurence
authors.initials: L
authors.lastname: Booth
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Cazanave
authors.forename: Hossein A
authors.initials: HA
authors.lastname: Hamed
authors.forename: Adly
authors.initials: A
authors.lastname: Yacoub
authors.forename: Besim
authors.initials: B
authors.lastname: Ogretmen
authors.forename: Ching-Shih
authors.initials: CS
authors.lastname: Chen
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000091342:Endoplasmic Reticulum Chaperone BiP; D055785:Gene Knockdown Techniques; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000378:metabolism; D006801:Humans; D051379:Mice; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology*; D014162:Transfection; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D051059:PTEN Phosphohydrolase; D011720:Pyrazoles; D013449:Sulfonamides; D019892:eIF-2 Kinase; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; C500894:OSU 03012; C494929:PTEN protein, human; C487757:Pten protein, mouse