title: A dominant-negative F-box deleted mutant of E3 ubiquitin ligase, β-TrCP1/FWD1, markedly reduces myeloma cell growth and survival in mice.
abstract: Treatment of multiple myeloma with bortezomib can result in severe adverse effects, necessitating the development of targeted inhibitors of the proteasome. We show that stable expression of a dominant-negative F-box deleted (âF) mutant of the E3 ubiquitin ligase, SCFβ-TrCP/FWD1, in murine 5TGM1 myeloma cells dramatically attenuated their skeletal engraftment and survival when inoculated into immunocompetent C57BL/KaLwRij mice. Similar results were obtained in immunodeficient bg-nu-xid mice, suggesting that the observed effects were independent of host recipient immune status. Bone marrow stroma offered no protection for 5TGM1-âF cells in cocultures treated with tumor necrosis factor (TNF), indicating a cell-autonomous anti-myeloma effect. Levels of p100, IκBα, Mcl-1, ATF4, total and cleaved caspase-3, and phospho-β-catenin were elevated in 5TGM1-âF cells whereas cIAP was down-regulated. TNF also activated caspase-3 and downregulated Bcl-2, correlating with the enhanced susceptibility of 5TGM1-âF cells to apoptosis. Treatment of 5TGM1 tumor-bearing mice with a β-TrCP1/FWD1 inhibitor, pyrrolidine dithiocarbamate (PDTC), significantly reduced tumor burden in bone. PDTC also increased levels of cleaved Mcl-1 and caspase-3 in U266 human myeloma cells, correlating with our murine data and validating the development of specific β-TrCP inhibitors as an alternative therapy to nonspecific proteasome inhibitors for myeloma patients.
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Williams
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Anjana
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Brandon
authors.initials: B
authors.lastname: McCluskey
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Current address: Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.
authors.forename: Shylesh
authors.initials: S
authors.lastname: Bhaskaran
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Current address: Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Muñoz
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Cancer Therapy and Research Center, San Antonio, TX, USA.
authors.forename: Babatunde O
authors.initials: BO
authors.lastname: Oyajobi
mesh_terms: D000818:Animals; D017209:Apoptosis; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology; D000069286:Bortezomib / Q000737:chemistry; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004789:Enzyme Activation; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009101:Multiple Myeloma / Q000378:metabolism*; D009154:Mutation; D009368:Neoplasm Transplantation; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry; D017154:Stromal Cells / Q000166:cytology; D013859:Thiocarbamates / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism; D051176:beta Catenin / Q000737:chemistry; D044844:beta-Transducin Repeat-Containing Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C471644:BTRC protein, human; C471643:Btrc protein, mouse; D011759:Pyrrolidines; D013859:Thiocarbamates; D014409:Tumor Necrosis Factor-alpha; D051176:beta Catenin; D044844:beta-Transducin Repeat-Containing Proteins; C020972:pyrrolidine dithiocarbamic acid; D000069286:Bortezomib; D044767:Ubiquitin-Protein Ligases; D053148:Caspase 3; D046988:Proteasome Endopeptidase Complex
keywords: 5TGM1; FWD1/β-TrCP1; myeloma; plasmacytoma; proteasome