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Targeted inhibition of the deubiquitinating enzymes, USP 14 and UCHL 5, induces proteotoxic stress and apoptosis in W aldenström macroglobulinaemia tumour cells
Author(s) -
Chitta Kasyapa,
Paulus Aneel,
Akhtar Sharoon,
Blake Maja Kristin K.,
Caulfield Thomas R.,
Novak Anne J.,
Ansell Stephen M.,
Advani Pooja,
Ailawadhi Sikander,
Sher Taimur,
Linder Stig,
ChananKhan Asher
Publication year - 2015
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/bjh.13304
Subject(s) - proteasome , bortezomib , apoptosis , deubiquitinating enzyme , unfolded protein response , microbiology and biotechnology , biology , proteasome inhibitor , endoplasmic reticulum , ubiquitin , immunology , biochemistry , gene , multiple myeloma
Summary Deubiquitinase enzymes ( DUB s) of the proteasomal 19S regulatory particle are emerging as important therapeutic targets in several malignancies. Here we demonstrate that inhibition of two proteasome‐associated DUB s ( USP 14 and UCHL 5) with the small molecule DUB inhibitor b‐ AP 15, results in apoptosis of human Waldenström macroglobulinaemia ( WM ) cell lines and primary patient‐derived WM tumour cells. Importantly, b‐ AP 15 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‐ AP 15 with USP 14 or UCHL 5 and proteasome enzyme activity assays confirmed that b‐ AP 15 does not affect the proteolytic capabilities of the 20S proteasome β‐subunits. In vitro toxicity from b‐ AP 15 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‐ AP 15‐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‐ AP 15 in vitro . This is the first report to define the effects and underlying mechanisms associated with inhibition of USP 14 and UCHL 5 DUB activity in WM tumour cells.