title: Targeted inhibition of the deubiquitinating enzymes, USP14 and UCHL5, induces proteotoxic stress and apoptosis in Waldenström macroglobulinaemia tumour cells.
abstract: Deubiquitinase enzymes (DUBs) of the proteasomal 19S regulatory particle are emerging as important therapeutic targets in several malignancies. Here we demonstrate that inhibition of two proteasome-associated DUBs (USP14 and UCHL5) with the small molecule DUB inhibitor b-AP15, results in apoptosis of human Waldenström macroglobulinaemia (WM) cell lines and primary patient-derived WM tumour cells. Importantly, b-AP15 produced proteotoxic stress and apoptosis in WM cells that have acquired resistance to the proteasome inhibitor bortezomib. In silico modelling identified protein residues that were critical for the binding of b-AP15 with USP14 or UCHL5 and proteasome enzyme activity assays confirmed that b-AP15 does not affect the proteolytic capabilities of the 20S proteasome β-subunits. In vitro toxicity from b-AP15 appeared to result from a build-up of ubiquitinated proteins and activation of the endoplasmic reticulum stress response in WM cells, an effect that also disrupted the mitochondria. Focused transcriptome profiling of b-AP15-treated WM cells revealed modulation of several genes regulating cell stress and NF-κB signalling, the latter whose protein translocation and downstream target activation was reduced by b-AP15 in vitro. This is the first report to define the effects and underlying mechanisms associated with inhibition of USP14 and UCHL5 DUB activity in WM tumour cells.
authors.affiliation: Department of Cancer Biology, Mayo Clinic, Jacksonville, FL, USA.
authors.forename: Kasyapa
authors.initials: K
authors.lastname: Chitta
authors.forename: Aneel
authors.initials: A
authors.lastname: Paulus
authors.forename: Sharoon
authors.initials: S
authors.lastname: Akhtar
authors.forename: Maja Kristin K
authors.initials: MK
authors.lastname: Blake
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Caulfield
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Novak
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Ansell
authors.forename: Pooja
authors.initials: P
authors.lastname: Advani
authors.forename: Sikander
authors.initials: S
authors.lastname: Ailawadhi
authors.forename: Taimur
authors.initials: T
authors.lastname: Sher
authors.forename: Stig
authors.initials: S
authors.lastname: Linder
authors.forename: Asher
authors.initials: A
authors.lastname: Chanan-Khan
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D016000:Cluster Analysis; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020869:Gene Expression Profiling; D053263:Gene Regulatory Networks; D006801:Humans; D008025:Ligases / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008958:Models, Molecular; D008968:Molecular Conformation; D016328:NF-kappa B / Q000378:metabolism; D010881:Piperidones / Q000737:chemistry / Q000494:pharmacology; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D021381:Protein Transport; D059748:Proteolysis; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects*; D008258:Waldenstrom Macroglobulinemia / Q000235:genetics / Q000378:metabolism*
chemical_list: C569633:3,5-bis((4-nitrophenyl)methylidene)-1-prop-2-enoylpiperidin-4-one; D016328:NF-kappa B; D010881:Piperidones; D011480:Protease Inhibitors; C509299:USP14 protein, human; C421245:UCHL5 protein, human; D043222:Ubiquitin Thiolesterase; D046988:Proteasome Endopeptidase Complex; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases
keywords: Waldenströms macroglobulinaemia; deubiquitinase enzymes; preclinical; proteasome; transcriptome