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: Yiping Che, O Giles Best, Ling Zhong, Kimberley L Kaufman, Swetlana Mactier, Mark Raftery, Lee M Graves, Stephen P Mulligan, Richard I Christopherson
• Journal: Journal of proteome research (J Proteome Res) Vol. 12 Issue 4 Pg. 1710-22 (Apr 05 2013) ISSN: 1535-3907 [Electronic] United States
• PMID: 23458665 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Benzamides
• Endoplasmic Reticulum Chaperone BiP
• HSP90 Heat-Shock Proteins
• HSPA5 protein, human
• Proteome
• SNX-7081

Topics

• Apoptosis (drug effects)
• Benzamides (pharmacology)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• DNA Repair (drug effects)
• DNA Replication (drug effects)
• Endoplasmic Reticulum Chaperone BiP
• Genes, p53
• HSP90 Heat-Shock Proteins (antagonists & inhibitors, metabolism)
• Humans
• Leukemia, Lymphocytic, Chronic, B-Cell (drug therapy, metabolism, pathology)
• Proteome (analysis, genetics, metabolism)
• Reproducibility of Results
• Tandem Mass Spectrometry