Molecular pathways: translational potential of deubiquitinases as drug targets (original) (raw)
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Proteasome-associated deubiquitinases and cancer
Cancer and Metastasis Reviews, 2017
Maintenance of protein homeostasis is a crucial process for the normal functioning of the cell. The regulated degradation of proteins is primarily facilitated by the ubiquitin proteasome system (UPS), a system of selective tagging of proteins with ubiquitin followed by proteasome-mediated proteolysis. The UPS is highly dynamic consisting of both ubiquitination and deubiquitination steps that modulate protein stabilization and degradation. Deregulation of protein stability is a common feature in the development and progression of numerous cancer types. Simultaneously, the elevated protein synthesis rate of cancer cells and consequential accumulation of misfolded proteins drives UPS addiction, thus sensitizing them to UPS inhibitors. This sensitivity along with the potential of stabilizing pro-apoptotic signaling pathways makes the proteasome an attractive clinical target for the development of novel therapies. Targeting of the catalytic 20S subunit of the proteasome is already a clinically validated strategy in multiple myeloma and other cancers. Spurred on by this success, promising novel inhibitors of the UPS have entered development, targeting the 20S as well as regulatory 19S subunit and inhibitors of deubiquitinating and ubiquitin ligase enzymes. In this review, we outline the manner in which deregulation of the UPS can cause cancer to develop, current clinical application of proteasome inhibitors, and the (pre-)clinical development of novel inhibitors of the UPS.
Cancer Research, 2014
The ubiquitin-proteasome system (UPS) has emerged as a therapeutic focus and target for the treatment of cancer. The most clinically successful UPS-active agents (bortezomib and lenalidomide) are limited in application to hematologic malignancies, with only marginal efficacy in solid tumors. Inhibition of specific ubiquitin E3 ligases has also emerged as a valid therapeutic strategy, and many targets are currently being investigated. Another emerging and promising approach in regulation of the UPS involves targeting deubiquitinases (DUB). The DUBs comprise a relatively small group of proteins, most with cysteine protease activity that target several key proteins involved in regulation of tumorigenesis, apoptosis, senescence, and autophagy. Through their multiple contacts with ubiquitinated protein substrates involved in these pathways, DUBs provide an untapped means of modulating many important regulatory proteins that support oncogenic transformation and progression. Ubiquitin-specific proteases (USP) are one class of DUBs that have drawn special attention as cancer targets, as many are differentially expressed or activated in tumors or their microenvironment, making them ideal candidates for drug development. This review attempts to summarize the USPs implicated in different cancers, the current status of USP inhibitor-mediated pharmacologic intervention, and future prospects for USP inhibitors to treat diverse cancers. Cancer Res; 74(18); 4955-66. Ó2014 AACR.
Ubiquitin-Specific Proteases: Players in Cancer Cellular Processes
Pharmaceuticals
Ubiquitination represents a post-translational modification (PTM) essential for the maintenance of cellular homeostasis. Ubiquitination is involved in the regulation of protein function, localization and turnover through the attachment of a ubiquitin molecule(s) to a target protein. Ubiquitination can be reversed through the action of deubiquitinating enzymes (DUBs). The DUB enzymes have the ability to remove the mono- or poly-ubiquitination signals and are involved in the maturation, recycling, editing and rearrangement of ubiquitin(s). Ubiquitin-specific proteases (USPs) are the biggest family of DUBs, responsible for numerous cellular functions through interactions with different cellular targets. Over the past few years, several studies have focused on the role of USPs in carcinogenesis, which has led to an increasing development of therapies based on USP inhibitors. In this review, we intend to describe different cellular functions, such as the cell cycle, DNA damage repair, ch...
Deubiquitinase inhibition as a cancer therapeutic strategy
Pharmacology & therapeutics, 2015
The ubiquitin proteasome system (UPS) is the main system for controlled protein degradation and a key regulator of fundamental cellular processes. The dependency of cancer cells on a functioning UPS has made this an attractive target for development of drugs that show selectivity for tumor cells. Deubiquitinases (DUBs, ubiquitin isopeptidases) are components of the UPS that catalyze the removal of ubiquitin moieties from target proteins or polyubiquitin chains, resulting in altered signaling or changes in protein stability. A number of DUBs regulate processes associated with cell proliferation and apoptosis, and as such represent candidate targets for cancer therapeutics. The majority of DUBs are cysteine proteases and are likely to be more "druggable" than E3 ligases. Cysteine residues in the active sites of DUBs are expected to be reactive to various electrophiles. Various compounds containing α,β-unsaturated ketones have indeed been demonstrated to inhibit cellular DUB ...
Cancers
The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. This process is tightly regulated through the activation and transfer of polyubiquitin chains to target proteins which are then recognized and degraded by the 26S proteasome complex. The role of UPS is crucial in regulating protein levels through degradation to maintain fundamental cellular processes such as growth, division, signal transduction, and stress response. Dysregulation of the UPS, resulting in loss of ability to maintain protein quality through proteolysis, is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss functional links of dysregulated UPS in human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing ...
Deubiquitinating Enzymes as Therapeutic Targets in Cancer
Abnormal regulation of the ubiquitin-proteasome system (UPS) has been known to be involved in the pathogenesis of a variety of human diseases. A number of studies have focused on the identification of small modifiers for the UPS. Even though the proteasome inhibitor Bortezomib (Velcade ®) has been approved for the therapy of multiple myeloma and mantle cell lymphoma, there are still no DUB inhibitors endorsed for clinical usage. Since deubiquitinating enzymes (DUBs) are becoming as a new class of modifiers in the UPS, potential drugs that target specific DUBs have been investigated with the development of experimental technologies for screening small inhibitor molecules. However, the molecular mechanisms of these molecules are poorly understood. In order to design and develop specific small inhibitor molecules for specific DUBs, identification of specific substrates and molecular structures for each DUB is required. Here, we review structures, substrates, and small inhibitor molecules of DUBs identified up to date, providing a clear rationale for the development of novel small inhibitor molecules of DUBs for cancer.
Deubiquitinating enzymes as novel anticancer targets
Future Oncology, 2007
Tagging proteins with mono-or poly-ubiquitin is now recognized as a multifaceted and universal means of regulating cell growth and physiology. It does so by controlling the cellular lifetime of nearly all eukaryotic proteins and the cellular localization of many critical proteins. Enzymes of the ubiquitin pathway add (ligases) or remove (deubiquitinases [DUBs]) ubiquitin tags to or from their target proteins in a selective fashion. Similarly to the kinases and their corresponding phosphatases, ubiquitin ligases and DUBs have become actively studied molecular oncology targets for drug discovery. Approximately 79 functional DUBs exist in the human proteome, suggesting that selective intervention is a reasonable therapeutic objective, with the goal of downregulating or ablating oncogene products or, alternatively, upregulating or sparing tumor suppressors. In the following review, this fascinating class of regulatory enzymes will be described, and specific examples of DUBs that are viable targets for anticancer therapy will be considered.
Drug Resistance Updates, 2015
The ubiquitin-proteasome system (UPS) is the primary mechanism controlling the degradation of damaged, unwanted or short-lived proteins in eukaryotic cells. In addition to protein homeostasis, the UPS has also emerged as a critical node in the regulation of signalling pathways implicated in the growth and survival of cancer cells. The absolute dependency of cancer cells on a functioning UPS has been exploited in the development of anti-cancer therapies as exemplified by development of proteasome inhibitors for the treatment of certain leukemic malignancies. Deubiquitinases (DUBs) are enzyme components of the UPS that catalyse re-editing of poly ubiquitin chains and/or removal of ubiquitin en bloc from target substrates leading to alterations in protein stability and/or downstream signalling. There is a growing recognition that targeting DUB activity may be a feasible option for the development of novel anti-cancer therapies. In particular inhibition of proteasomal cysteine DUBs (i.e. USP14 and UCHL5) has been shown to be particularly cytotoxic to cancer cells leading to the accumulation of ubiquitinated proteins and proteotoxic stress. In this review we focus on the mechanisms of action of proteasome DUB inhibitors as well as the potential of such compounds to circumvent acquired drug resistance in cancer patients.
Advances in Deubiquitinating Enzyme Inhibition and Applications in Cancer Therapeutics
Cancers
Since the discovery of the ubiquitin proteasome system (UPS), the roles of ubiquitinating and deubiquitinating enzymes (DUBs) have been widely elucidated. The ubiquitination of proteins regulates many aspects of cellular functions such as protein degradation and localization, and also modifies protein-protein interactions. DUBs cleave the attached ubiquitin moieties from substrates and thereby reverse the process of ubiquitination. The dysregulation of these two paramount pathways has been implicated in numerous diseases, including cancer. Attempts are being made to identify inhibitors of ubiquitin E3 ligases and DUBs that potentially have clinical implications in cancer, making them an important target in the pharmaceutical industry. Therefore, studies in medicine are currently focused on the pharmacological disruption of DUB activity as a rationale to specifically target cancer-causing protein aberrations. Here, we briefly discuss the pathophysiological and physiological roles of ...