title: Suberoylanilide hydroxamic acid induces ROS-mediated cleavage of HSP90 in leukemia cells.
abstract: Heat shock protein 90 (HSP90) is a molecular chaperone that supports stability of client proteins. We found that HSP90 was cleaved to 55 kDa protein after treatment with histone deacetylase (HDAC) inhibitors including suberoylanilide hydroxamic acid (SAHA) in several leukemia cell lines. We further analyzed molecular changes induced by SAHA in K562 cells. The SAHA-induced cleavage of HSP90 was blocked by a pan-caspase inhibitor, z-VAD-fmk, implying that the process is dependent on caspase activity. However, the experiments using antagonistic and agonistic Fas antibodies revealed that the cleavage of HSP90 was not dependent on Fas signaling. SAHA induced generation of reactive oxygen species (ROS), and the cleavage of HSP90 was blocked by a ROS scavenger N-acetylcystein (NAC). We also confirmed that hydrogen peroxide (H2O2) induced cleavage of HSP90 in a similar manner. Caspase 2, 3, 4, 6, 8, and 10 were activated by treatment with SAHA, and the activities were reduced by the pretreatment of NAC. Treatment of the cells with caspase 10 inhihitor, but not other inhibitors of caspases activated by SAHA, prevented cleavage of HSP90 by SAHA. SAHA-induced ROS generation and HSP90 cleavage were dependent on newly synthesized unknown proteins. Taken together, our results suggest that the cleavage of HSP90 by SAHA is mediated by ROS generation and caspase 10 activation. HSP90 cleavage may provide an additional mechanism involved in anti-cancer effects of HDAC inhibitors.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, Chungbuk, 361-763, Republic of Korea.
authors.forename: Sangkyu
authors.initials: S
authors.lastname: Park
authors.forename: Jeong-A
authors.initials: JA
authors.lastname: Park
authors.forename: Young-Eun
authors.initials: YE
authors.lastname: Kim
authors.forename: Sukgil
authors.initials: S
authors.lastname: Song
authors.forename: Hyung-Joo
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Younghee
authors.initials: Y
authors.lastname: Lee
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D053455:Caspase 10 / Q000378:metabolism; D061945:Caspase Inhibitors / Q000494:pharmacology; D020169:Caspases / Q000737:chemistry / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006877:Hydroxamic Acids / Q000494:pharmacology*; D020014:K562 Cells; D007938:Leukemia; D059748:Proteolysis / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D000077337:Vorinostat; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; C491901:FAS protein, human; D018841:HSP90 Heat-Shock Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D017382:Reactive Oxygen Species; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D000077337:Vorinostat; D006861:Hydrogen Peroxide; D053455:Caspase 10; D020169:Caspases; D000111:Acetylcysteine