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The small heat shock protein B8 (HSPB8) confers resistance to bortezomib by promoting autophagic removal of misfolded proteins in multiple myeloma cells.

ABSTRACT: Velcade is one of the inescapable drug to treat patient suffering from multiple myeloma (MM) and resistance to this drug represents a major drawback for patients. However, the mechanisms underlying velcade resistance remain incompletely understood. We derived several U266 MM cell clones that resist to velcade. U266-resistant cells were resistant to velcade-induced cell death but exhibited a similar sensitivity to various proapoptotic stimuli. Careful analysis of proteosomal subunits and proteasome enzymatic activities showed that neither the composition nor the activity of the proteasome was affected in velcade-resistant cells. Elimination of velcade-induced poly-ubiquitinated proteins and protein aggregates was drastically stimulated in the resistant cells and correlated with increased cell survival. Inhibition of the lysosomal activity in velcade-resistant cells resulted in an increase of cell aggregates and decrease survival, indicating that aggregates are eliminated through lysosomal degradation. In addition, pangenomic profiling of velcade-sensitive and resistant cells showed that the small heat shock protein HSPB8 was overexpressed in resistant cells. Finally, gain and loss of function experiment demonstrated that HSPB8 is a key factor for velcade resistance. In conclusion, HSPB8 plays an important role for the elimination of aggregates in velcade-resistant cells that contributes to their enhanced survival.

SUBMITTER: Hamouda MA

PROVIDER: S-EPMC4171627 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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The small heat shock protein B8 (HSPB8) confers resistance to bortezomib by promoting autophagic removal of misfolded proteins in multiple myeloma cells.

Hamouda Mohamed-Amine MA Belhacene Nathalie N Puissant Alexandre A Colosetti Pascal P Robert Guillaume G Jacquel Arnaud A Mari Bernard B Auberger Patrick P Luciano Frederic F

Oncotarget 20140801 15

Velcade is one of the inescapable drug to treat patient suffering from multiple myeloma (MM) and resistance to this drug represents a major drawback for patients. However, the mechanisms underlying velcade resistance remain incompletely understood. We derived several U266 MM cell clones that resist to velcade. U266-resistant cells were resistant to velcade-induced cell death but exhibited a similar sensitivity to various proapoptotic stimuli. Careful analysis of proteosomal subunits and proteaso ...[more]

PMID: 25051369

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Project description:BackgroundHigh-dose chemotherapy plus autologous stem-cell transplantation has been the standard treatment for newly diagnosed multiple myeloma in adults up to 65 years of age. However, promising data on the use of combination therapy with lenalidomide, bortezomib, and dexamethasone (RVD) in this population have raised questions about the role and timing of transplantation.MethodsWe randomly assigned 700 patients with multiple myeloma to receive induction therapy with three cycles of RVD and then consolidation therapy with either five additional cycles of RVD (350 patients) or high-dose melphalan plus stem-cell transplantation followed by two additional cycles of RVD (350 patients). Patients in both groups received maintenance therapy with lenalidomide for 1 year. The primary end point was progression-free survival.ResultsMedian progression-free survival was significantly longer in the group that underwent transplantation than in the group that received RVD alone (50 months vs. 36 months; adjusted hazard ratio for disease progression or death, 0.65; P<0.001). This benefit was observed across all patient subgroups, including those stratified according to International Staging System stage and cytogenetic risk. The percentage of patients with a complete response was higher in the transplantation group than in the RVD-alone group (59% vs. 48%, P=0.03), as was the percentage of patients in whom minimal residual disease was not detected (79% vs. 65%, P<0.001). Overall survival at 4 years did not differ significantly between the transplantation group and the RVD-alone group (81% and 82%, respectively). The rate of grade 3 or 4 neutropenia was significantly higher in the transplantation group than in the RVD-alone group (92% vs. 47%), as were the rates of grade 3 or 4 gastrointestinal disorders (28% vs. 7%) and infections (20% vs. 9%). No significant between-group differences were observed in the rates of treatment-related deaths, second primary cancers, thromboembolic events, and peripheral neuropathy.ConclusionsAmong adults with multiple myeloma, RVD therapy plus transplantation was associated with significantly longer progression-free survival than RVD therapy alone, but overall survival did not differ significantly between the two approaches. (Supported by Celgene and others; IFM 2009 Study ClinicalTrials.gov number, NCT01191060 .).

Dataset Information

The small heat shock protein B8 (HSPB8) confers resistance to bortezomib by promoting autophagic removal of misfolded proteins in multiple myeloma cells.

Publications

The small heat shock protein B8 (HSPB8) confers resistance to bortezomib by promoting autophagic removal of misfolded proteins in multiple myeloma cells.

Similar Datasets

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