title: Identification of the APC/C co-factor FZR1 as a novel therapeutic target for multiple myeloma.
abstract: Multiple Myeloma (MM) is a haematological neoplasm characterised by the clonal proliferation of malignant plasma cells in the bone marrow. The success of proteasome inhibitors in the treatment of MM has highlighted the importance of the ubiquitin proteasome system (UPS) in the pathogenesis of this disease. In this study, we analysed gene expression of UPS components to identify novel therapeutic targets within this pathway in MM. Here we demonstrate how this approach identified previously validated and novel therapeutic targets. In addition we show that FZR1 (Fzr), a cofactor of the multi-subunit E3 ligase complex anaphase-promoting complex/cyclosome (APC/C), represents a novel therapeutic target in myeloma. The APC/C associates independently with two cofactors, Fzr and Cdc20, to control cell cycle progression. We found high levels of FZR1 in MM primary cells and cell lines and demonstrate that expression is further increased on adhesion to bone marrow stromal cells (BMSCs). Specific knockdown of either FZR1 or CDC20 reduced viability and induced growth arrest of MM cell lines, and resulted in accumulation of APC/CFzr substrate Topoisomerase IIα (TOPIIα) or APC/CCdc20 substrate Cyclin B. Similar effects were observed following treatment with proTAME, an inhibitor of both APC/CFzr and APC/CCdc20. Combinations of proTAME with topoisomerase inhibitors, etoposide and doxorubicin, significantly increased cell death in MM cell lines and primary cells, particularly if TOPIIα levels were first increased through pre-treatment with proTAME. Similarly, combinations of proTAME with the microtubule inhibitor vincristine resulted in enhanced cell death. This study demonstrates the potential of targeting the APC/C and its cofactors as a therapeutic approach in MM.
authors.affiliation: Centre for Cancer Research and Cell Biology (CCRCB), Queen's University Belfast, Belfast, UK.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Crawford
authors.affiliation: Centre for Cancer Research and Cell Biology (CCRCB), Queen's University Belfast, Belfast, UK.
authors.forename: Gordon
authors.initials: G
authors.lastname: Anderson
authors.affiliation: Centre for Cancer Research and Cell Biology (CCRCB), Queen's University Belfast, Belfast, UK.
authors.forename: Cliona K
authors.initials: CK
authors.lastname: Johnston
authors.affiliation: Centre for Cancer Research and Cell Biology (CCRCB), Queen's University Belfast, Belfast, UK.
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Irvine
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D064199:Cdc20 Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D064200:Cdh1 Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009101:Multiple Myeloma / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference
chemical_list: D000970:Antineoplastic Agents; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; C577584:FZR1 protein, human; C577488:CDC20 protein, human; D064173:Anaphase-Promoting Complex-Cyclosome
keywords: APC/C; FZR1; multiple myeloma; proTAME; ubiquitin proteasome system