Dataset Information

Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

ABSTRACT: Bortezomib (Velcade™) is a reversible proteasome inhibitor that is approved for the treatment of multiple myeloma (MM). Despite its demonstrated clinical success, some patients are deprived of treatment due to primary refractoriness or development of resistance during therapy. To investigate the role of the duration of proteasome inhibition in the anti-tumor response of bortezomib, we established clonal isolates of HT-29 adenocarcinoma cells adapted to continuous exposure of bortezomib. These cells were ~30-fold resistant to bortezomib. Two novel and distinct mutations in the ?5 subunit, Cys63Phe, located distal to the binding site in a helix critical for drug binding, and Arg24Cys, found in the propeptide region were found in all resistant clones. The latter mutation is a natural variant found to be elevated in frequency in patients with MM. Proteasome activity and levels of both the constitutive and immunoproteasome were increased in resistant cells, which correlated to an increase in subunit gene expression. These changes correlated with a more rapid recovery of proteasome activity following brief exposure to bortezomib. Increased recovery rate was not due to increased proteasome turnover as similar findings were seen in cells co-treated with cycloheximide. When we exposed resistant cells to the irreversible proteasome inhibitor carfilzomib we noted a slower rate of recovery of proteasome activity as compared to bortezomib in both parental and resistant cells. Importantly, carfilzomib maintained its cytotoxic potential in the bortezomib resistant cell lines. Therefore, resistance to bortezomib, can be overcome with irreversible inhibitors, suggesting prolonged proteasome inhibition induces a more potent anti-tumor response.

SUBMITTER: Suzuki E

PROVIDER: S-EPMC3245226 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

Suzuki Erika E Demo Susan S Deu Edgar E Keats Jonathan J Arastu-Kapur Shirin S Bergsagel P Leif PL Bennett Mark K MK Kirk Christopher J CJ

PloS one 20111222 12

Bortezomib (Velcade™) is a reversible proteasome inhibitor that is approved for the treatment of multiple myeloma (MM). Despite its demonstrated clinical success, some patients are deprived of treatment due to primary refractoriness or development of resistance during therapy. To investigate the role of the duration of proteasome inhibition in the anti-tumor response of bortezomib, we established clonal isolates of HT-29 adenocarcinoma cells adapted to continuous exposure of bortezomib. These ce ...[more]

PMID: 22216088

Similar Datasets

Project description:Mechanisms underlying interactions between a novel, clinically relevant circularized tumor necrosis factor-related apoptosis inducing ligand (TRAIL) agonist, circularly permuted TRAIL (CPT) have been examined in multiple myeloma (MM) cells sensitive or resistant to bortezomib (BTZ). Various MM cell lines for example, U266, including those resistant to bortezomib-resistant U266 cells were exposed to low nanomolar concentrations of bortezomib ± CPT and apoptosis monitored. Circularly permuted TRAIL and bortezomib synergistically induced apoptosis in both BTZ-naïve and -resistant cells. The regimen up-regulated DR4 receptor internalization in MM cells, known to modulate both NF-κB and extrinsic apoptotic pathways. CPT/BTZ disrupted the non-canonical NF-κB pathway, reflected by tumor necrosis factor (TNF) receptor associated factors 3 (TRAF3) up-regulation, NF-κB inducing kinase down-regulation, diminished p52 and p50 processing, and B-cell lymphoma-extra large (BCL-XL) down-regulation, but failed to inactivate the canonical NF-κB pathway, reflected by unchanged or increased expression of phospho-p65. The regimen also sharply increased extrinsic apoptotic pathway activation. Cells exhibiting TRAF3 knock-down, dominant-negative Fas-associated protein with death domain, knock-down of caspase-8, BCL-2/BCL-XL, or exposure to a caspase-9 inhibitor displayed markedly reduced CPT/BTZ sensitivity. Concordant results were observed in bortezomib-resistant cells. The regimen was also active in the presence of stromal cells and was relatively sparing toward normal CD34+ hematopoietic cells. Finally, ex vivo results revealed synergism in primary MM primary cells, including those BTZ, and the CPT/BTZ regimen significantly decreased tumor growth in a patient-derived MM xenograft model. These results indicate that the CPT/BTZ regimen acts via the non-canonical NF-κB as well as intrinsic/extrinsic apoptotic pathways to induce cell death in MM cells, and may represent an effective strategy in the setting of bortezomib resistance.

Dataset Information

Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

Publications

Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets