title: Hsp90 Inhibitor SNX-7081 dysregulates proteins involved with DNA repair and replication and the cell cycle in human chronic lymphocytic leukemia (CLL) cells.
abstract: The proteomic effects of the Hsp90 inhibitor, SNX-7081, have been determined on the p53-mutated B-cell chronic lymphocytic leukemia (CLL) cell line, MEC1. Following SNX-7081 treatment (500 nM, 24 h), 51 proteins changed abundance by more than 2-fold (p < 0.05); 7 proteins increased while 44 proteins decreased. Proteins identified as differentially abundant by LC-MS/MS were validated by Western blotting (DDB1, PCNA, MCM2, Hsp90, Hsp70, GRP78, PDIA6, HLA-DR). RT-PCR showed that SNX-7081 unexpectedly modulates a number of these proteins in MEC1 cells at the mRNA level (PCNA, MCM2, Nup155, Hsp70, GRP78, PDIA6, and HLA-DR). Pathway analysis determined that 3 of the differentially abundant proteins (cyclin D1, c-Myc and pRb) were functionally related. p53 levels did not change upon SNX-7081 treatment of p53 wild-type Raji cells or p53-mutated MEC1 and U266 cells, indicating that SNX-7081 has a p53-independent mechanism. The decreases in DDB1, MCM2, c-Myc, and PCNA and increases of pRb and cyclin D1 were confirmed in MEC1, U266, Raji, and p53 null HL60 cells by Western blotting. These data suggest that SNX-7081 arrests the cell cycle and inhibits DNA replication and r epair and provides evidence for the mechanism of the observed synergy between Hsp90 inhibitors and drugs that induce DNA strand breaks.
authors: Cancer Proteomics Laboratory, School of Molecular Bioscience, University of Sydney , Sydney, NSW 2006, Australia.
authors: Yiping
authors: Y
authors: Che
authors: O Giles
authors: OG
authors: Best
authors: Ling
authors: L
authors: Zhong
authors: Kimberley L
authors: KL
authors: Kaufman
authors: Swetlana
authors: S
authors: Mactier
authors: Mark
authors: M
authors: Raftery
authors: Lee M
authors: LM
authors: Graves
authors: Stephen P
authors: SP
authors: Mulligan
authors: Richard I
authors: RI
authors: Christopherson
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D004260:DNA Repair / Q000187:drug effects*; D004261:DNA Replication / Q000187:drug effects; D000091342:Endoplasmic Reticulum Chaperone BiP; D016158:Genes, p53; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D020543:Proteome / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry
chemical_list: D001549:Benzamides; D000091342:Endoplasmic Reticulum Chaperone BiP; D018841:HSP90 Heat-Shock Proteins; C000717247:HSPA5 protein, human; D020543:Proteome; C535175:SNX-7081