title: MiR-29b replacement inhibits proteasomes and disrupts aggresome+autophagosome formation to enhance the antimyeloma benefit of bortezomib.
abstract: Evading apoptosis is a cancer hallmark that remains a serious obstacle in current treatment approaches. Although proteasome inhibitors (PIs) have transformed management of multiple myeloma (MM), drug resistance emerges through induction of the aggresome+autophagy pathway as a compensatory protein clearance mechanism. Genome-wide profiling identified microRNAs (miRs) differentially expressed in bortezomib-resistant myeloma cells compared with drug-naive cells. The effect of individual miRs on proteasomal degradation of short-lived fluorescent reporter proteins was then determined in live cells. MiR-29b was significantly reduced in bortezomib-resistant cells as well as in cells resistant to second-generation PIs carfilzomib and ixazomib. Luciferase reporter assays demonstrated that miR-29b targeted PSME4 that encodes the proteasome activator PA200. Synthetically engineered miR-29b replacements impaired the growth of myeloma cells, patient tumor cells and xenotransplants. MiR-29b replacements also decreased PA200 association with proteasomes, reduced the proteasome's peptidase activity and inhibited ornithine decarboxylase turnover, a proteasome substrate degraded through ubiquitin-independent mechanisms. Immunofluorescence studies revealed that miR-29b replacements enhanced the bortezomib-induced accumulation of ubiquitinated proteins but did not reveal aggresome or autophagosome formation. Taken together, our study identifies miR-29b replacements as the first-in-class miR-based PIs that also disrupt the autophagy pathway and highlight their potential to synergistically enhance the antimyeloma effect of bortezomib.
authors.affiliation: 1] The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA [2] Division of Hematology and Oncology, The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: S
authors.initials: S
authors.lastname: Jagannathan
authors.affiliation: 1] The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA [2] Division of Hematology and Oncology, The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: N
authors.initials: N
authors.lastname: Vad
authors.affiliation: Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: S
authors.initials: S
authors.lastname: Vallabhapurapu
authors.affiliation: Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: S
authors.initials: S
authors.lastname: Vallabhapurapu
authors.affiliation: Jerome Lipper Multiple Myeloma Center and LeBow Institute for Myeloma Therapeutics, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Anderson
authors.affiliation: 1] The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA [2] Division of Hematology and Oncology, The Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, OH, USA [3] Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Driscoll
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D016688:Mice, Inbred NOD; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D009368:Neoplasm Transplantation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000378:metabolism; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism; D061251:Primary Cell Culture; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D016019:Survival Analysis
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; D000069286:Bortezomib; D035683:MicroRNAs; D009687:Nuclear Proteins; D009955:Ornithine Decarboxylase; D046988:Proteasome Endopeptidase Complex; D011719:Pyrazines; D034741:RNA, Small Interfering; C532045:MIRN29a microRNA, human; C521188:PSME4 protein, human