Abstract
Objectives:
Hematopoietic stroma promotes resistance to immune control by APO2L/TRAIL in multiple myeloma (MM) cells in part by increasing synthesis of the anti-apoptotic protein c-FLIP. Here, we tested whether bortezomib can reverse the APO2L/TRAIL environmental mediated-immune resistance (EM-IR).
Material and methods:
MM cell lines (RPMI 8226 and U266) and CD138+ patient's MM cells were directly adhered to HS5 stroma exposed to HS5 or bone marrow stroma of patients with MM released soluble factors in a transwell system. Cells were treated with either APO2L/TRAIL (10 ng/mL), bortezomib (10 nm) or both.
Results:
Pretreatment with bortezomib effectively overcomes APO2L/TRAIL apoptosis resistance in myeloma cell lines and in CD138+ cells while directly adhered or in transwell assay. Bortezomib was not cytotoxic to HS5 stroma cells and only altered monocyte chemotactic protein-2-3 and IL-10 levels in the stroma-myeloma milieu. Factors released by HS5 stroma increased expression of c-FLIP, induced STAT-3 and ERK phosphorylation and reduced DR4 receptor expression in MM cells. HS5 stroma-released factor(s) induced NF-kappaB activation after 20 h exposure in association with an enhanced c-FLIP transcription. Bortezomib effectively reduced c-FLIP protein expression without affecting other proteins. Bortezomib also increased DR4 and DR5 expression in the presence of stroma.
Conclusions:
These findings provide the rationale to combine bortezomib and APO2L/TRAIL to disrupt the influence of the stroma microenvironment on MM cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Apoptosis / drug effects*
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Boronic Acids / pharmacology*
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Boronic Acids / therapeutic use
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Bortezomib
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CASP8 and FADD-Like Apoptosis Regulating Protein / antagonists & inhibitors
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Cell Line, Tumor / drug effects
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Cells, Cultured / drug effects
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Cells, Cultured / metabolism
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Coculture Techniques
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Cytokines / biosynthesis
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Cytokines / genetics
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Drug Screening Assays, Antitumor
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Drug Synergism
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Gene Expression Regulation, Neoplastic / drug effects
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Humans
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Multiple Myeloma / pathology*
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Neoplasm Proteins / antagonists & inhibitors
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Neoplasm Proteins / biosynthesis
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Neoplasm Proteins / genetics
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Protease Inhibitors / pharmacology*
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Protease Inhibitors / therapeutic use
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Pyrazines / pharmacology*
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Pyrazines / therapeutic use
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Receptors, TNF-Related Apoptosis-Inducing Ligand / antagonists & inhibitors
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Receptors, TNF-Related Apoptosis-Inducing Ligand / physiology
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Receptors, Tumor Necrosis Factor / antagonists & inhibitors
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Receptors, Tumor Necrosis Factor / physiology
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Recombinant Proteins / pharmacology
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Stromal Cells / drug effects*
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Stromal Cells / metabolism
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TNF-Related Apoptosis-Inducing Ligand / pharmacology
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TNF-Related Apoptosis-Inducing Ligand / physiology*
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Tumor Escape / drug effects
Substances
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Boronic Acids
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CASP8 and FADD-Like Apoptosis Regulating Protein
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CFLAR protein, human
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Cytokines
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Neoplasm Proteins
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Protease Inhibitors
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Pyrazines
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Receptors, TNF-Related Apoptosis-Inducing Ligand
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Receptors, Tumor Necrosis Factor
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Recombinant Proteins
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TNF-Related Apoptosis-Inducing Ligand
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TNFRSF10A protein, human
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TNFSF10 protein, human
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Bortezomib