Document Detail

The Hsp90 inhibitor IPI-504 overcomes bortezomib resistance in mantle cell lymphoma in vitro and in vivo by down-regulation of the prosurvival ER chaperone BiP/Grp78.
MedLine Citation:
PMID:  21106982     Owner:  NLM     Status:  In-Data-Review    
Despite the promising introduction of the proteasome inhibitor bortezomib in the treatment of mantle cell lymphoma (MCL), not all patients respond, and resistance often appears after initial treatment. By analyzing a set of 18 MCL samples, including cell lines with constitutive or induced resistance to bortezomib, we found a high correlation between loss of sensitivity to the proteasome inhibitor and up-regulation of the prosurvival chaperone BiP/Grp78. BiP/Grp78 stabilization was ensured at a posttranscriptional level by an increase in the chaperoning activity of heat shock protein of 90 kDa (Hsp90). In bortezomib-resistant cells, both BiP/Grp78 knockdown and cell pretreatment with the Hsp90 inhibitor of the ansamycin class, IPI-504, led to synergistic induction of apoptotic cell death when combined with bortezomib. Cell exposure to the IPI-504-bortezomib combination provoked the dissociation of Hsp90/BiP complexes, leading to BiP/Grp78 depletion, inhibition of unfolded protein response, and promotion of NOXA-mediated mitochondrial depolarization. The IPI-504-bortezomib combination also prevented BiP/Grp78 accumulation, thereby promoting apoptosis and inhibiting the growth of bortezomib-resistant tumors in a mouse model of MCL xenotransplantation. These results suggest that targeting unfolded protein response activation by the inhibition of Hsp90 may be an attractive model for the design of a new bortezomib-based combination therapy for MCL.
Gaël Roué; Patricia Pérez-Galán; Ana Mozos; Mónica López-Guerra; Sílvia Xargay-Torrent; Laia Rosich; Ifigènia Saborit-Villarroya; Emmanuel Normant; Elias Campo; Dolors Colomer
Publication Detail:
Type:  Journal Article     Date:  2010-11-24
Journal Detail:
Title:  Blood     Volume:  117     ISSN:  1528-0020     ISO Abbreviation:  Blood     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7603509     Medline TA:  Blood     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1270-9     Citation Subset:  AIM; IM    
Hematopathology Unit, Department of Pathology, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain; and.
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