The proteasome deubiquitinase inhibitor VLX1570 shows selectivity for ubiquitin-specific protease-14 and induces apoptosis of multiple myeloma cells

• Published in: Scientific reports Vol. 6; no. 1; p. 26979
• Main Authors: Wang, Xin, Mazurkiewicz, Magdalena, Hillert, Ellin-Kristina, Olofsson, Maria Hägg, Pierrou, Stefan, Hillertz, Per, Gullbo, Joachim, Selvaraju, Karthik, Paulus, Aneel, Akhtar, Sharoon, Bossler, Felicitas, Khan, Asher Chanan, Linder, Stig, D’Arcy, Padraig
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.06.2016; Nature Publishing Group
• Subjects: 631/67/1059/602; 631/67/1990/804; 82; 82/103; 82/51; 82/80; 96; 96/106; 96/2; Animals; Antineoplastic Agents - chemistry; Antineoplastic Agents - metabolism; Antineoplastic Agents - pharmacology; Apoptosis; Apoptosis - drug effects; Azepines - chemistry; Azepines - metabolism; Azepines - pharmacology; Benzylidene Compounds - chemistry; Benzylidene Compounds - metabolism; Benzylidene Compounds - pharmacology; Cell cycle; Cell death; Cell Line, Tumor; Cell Proliferation - drug effects; Cell Survival; Enzyme Stability; Female; Humanities and Social Sciences; Humans; Medicin och hälsovetenskap; Mice, SCID; multidisciplinary; Multiple myeloma; Multiple Myeloma - drug therapy; Polyubiquitin - metabolism; Proteasome Endopeptidase Complex - metabolism; Proteasome Inhibitors - chemistry; Proteasome Inhibitors - metabolism; Proteasome Inhibitors - pharmacology; Protein Binding; Proteins; Proteolysis; Science; Science (multidisciplinary); Ubiquitin Thiolesterase - antagonists & inhibitors; Ubiquitin Thiolesterase - chemistry; Xenograft Model Antitumor Assays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep26979

Inhibition of deubiquitinase (DUB) activity is a promising strategy for cancer therapy. VLX1570 is an inhibitor of proteasome DUB activity currently in clinical trials for relapsed multiple myeloma. Here we show that VLX1570 binds to and inhibits the activity of ubiquitin-specific protease-14 (USP14) in vitro, with comparatively weaker inhibitory activity towards UCHL5 (ubiquitin-C-terminal hydrolase-5). Exposure of multiple myeloma cells to VLX1570 resulted in thermostabilization of USP14 at therapeutically relevant concentrations. Transient knockdown of USP14 or UCHL5 expression by electroporation of siRNA reduced the viability of multiple myeloma cells. Treatment of multiple myeloma cells with VLX1570 induced the accumulation of proteasome-bound high molecular weight polyubiquitin conjugates and an apoptotic response. Sensitivity to VLX1570 was moderately affected by altered drug uptake, but was unaffected by overexpression of BCL2-family proteins or inhibitors of caspase activity. Finally, treatment with VLX1570 was found to lead to extended survival in xenograft models of multiple myeloma. Our findings demonstrate promising antiproliferative activity of VLX1570 in multiple myeloma, primarily associated with inhibition of USP14 activity.