Proteasome-associated deubiquitinases and cancer (original) (raw)
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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 ...
Ubiquitin–proteasome system and the role of its inhibitors in cancer therapy
Open Biology
Despite all the other cells that have the potential to prevent cancer development and metastasis through tumour suppressor proteins, cancer cells can upregulate the ubiquitin–proteasome system (UPS) by which they can degrade tumour suppressor proteins and avoid apoptosis. This system plays an extensive role in cell regulation organized in two steps. Each step has an important role in controlling cancer. This demonstrates the importance of understanding UPS inhibitors and improving these inhibitors to foster a new hope in cancer therapy. UPS inhibitors, as less invasive chemotherapy drugs, are increasingly used to alleviate symptoms of various cancers in malignant states. Despite their success in reducing the development of cancer with the lowest side effects, thus far, an appropriate inhibitor that can effectively inactivate this system with the least drug resistance has not yet been fully investigated. A fundamental understanding of the system is necessary to fully elucidate its ro...
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.
The Ubiquitin-Proteasome Pathway and Its Role in Cancer
Journal of Clinical Oncology, 2005
Critical cellular processes are regulated, in part, by maintaining the appropriate intracellular levels of proteins. Whereas de novo protein synthesis is a comparatively slow process, proteins are rapidly degraded at a rate compatible with the control of cell cycle transitions and cell death induction. A major pathway for protein degradation is initiated by the addition of multiple 76 -amino acid ubiquitin monomers via a three-step process of ubiquitin activation and substrate recognition. Polyubiquitination targets proteins for recognition and processing by the 26S proteasome, a cylindrical organelle that recognizes ubiquitinated proteins, degrades the proteins, and recycles ubiquitin. The critical roles played by ubiquitin-mediated protein turnover in cell cycle regulation makes this process a target for oncogenic mutations. Oncogenes of several common malignancies, for example colon and renal cell cancer, code for ubiquitin ligase components. Cervical oncogenesis by human papillomavirus is also mediated by alteration of ubiquitin ligase pathways. Protein degradation pathways are also targets for cancer therapy, as shown by the successful introduction of bortezomib, an inhibitor of the 26S proteasome. Further work in this area holds great promise toward our understanding and treatment of a wide range of cancers. Fig 1. The ubiquitin-proteasome pathway. Proteins marked with a polyubiquitin chain by the E1-E2-E3 enzymatic cascade are targeted for degradation by the proteasome. A ubiquitin-activating enzyme (E1) binds ubiquitin in an adenosine triphosphate (ATP) -dependent step. Ubiquitin is then transferred to a ubiquitin-conjugating enzyme (E2). A ubiquitin ligase (E3) helps transfer ubiquitin to the target substrate. PPI, pyrophosphate; AMP, adenosine monophosphate; Ub, ubiquitin. (Figure and legend adapted 30 and used by permission from Elsevier.) Fig 2.
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...
Targeting the Ubiquitin Proteasome System in Cancer
The ubiquitin proteasome system is involved in a myriad of biological functions including cell cycle progression, intracellular signaling and protein degradation. As such, it is not surprising to find many components of the system misregulated in cancer. The clinical success of Bortezomib for treatment of multiple myeloma proves that targeting the ubiquitin proteasome system is valid and feasible. Here, a detailed examination of the strategies used to target the ubiquitin proteasome system in cancer is discussed. The inhib-itors available, its targets, the cancer type and the developmental stage it is in are discussed.
Targeting the Ubiquitin Proteasome System: Beyond Proteasome Inhibition
Current Pharmaceutical Design, 2013
The Ubiquitin-Proteasome System (UPS) has been considered as privileged pharmacological target for drug development due to the tremendous potential for intervention on multiple pathologies including cancer, neurodegenerative diseases, immune diseases and multiple infections. The pharmacological potential of the UPS was revealed after the unpredicted success of proteasome inhibitors for the treatment of some haematological malignancies. After a decade of clinical use of bortezomib, this review summarizes part of the learned experience and recent advances on the development of alternative inhibitors of the UPS. A new generation of inhibitors, including those targeting subsets of proteasomes, are under investigation and it is likely that some of them will reach clinical trials. Beyond the proteasome inhibition, there are also other targets that can be blocked to attain directly or indirectly the UPS system. The ubiquitylation status of protein substrates is intimately linked to other post-translational modifications of the ubiquitin family, increasing the number of potential targets for clinical intervention. In addition to the obvious subsets of ubiquitin-conjugating and de-conjugating enzymes, a group of enzymatic activities regulating SUMOylation or NEDDylation have a potential impact on the activity of the UPS. The novel strategies explore the active site of those enzymes and/or the target recognition surfaces. The first inhibitors of these parallel pathways appeared to tackle a limited number of protein targets playing important roles on diverse pathologies. Although, a large majority of them have not yet been tested in clinical trials, the new inhibitors are expected to have fewer side effects than proteasome inhibitors.
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.
Inhibition of proteasome deubiquitinating activity as a new cancer therapy
l e t t e r s nature medicine advance online publication Ubiquitin-tagged substrates are degraded by the 26S proteasome, which is a multisubunit complex comprising a proteolytic 20S core particle capped by 19S regulatory particles 1,2 . The approval of bortezomib for the treatment of multiple myeloma validated the 20S core particle as an anticancer drug target 3 . Here we describe the small molecule b-AP15 as a previously unidentified class of proteasome inhibitor that abrogates the deubiquitinating activity of the 19S regulatory particle. b-AP15 inhibited the activity of two 19S regulatory-particle-associated deubiquitinases, ubiquitin C-terminal hydrolase 5 (UCHL5) and ubiquitinspecific peptidase 14 (USP14), resulting in accumulation of polyubiquitin. b-AP15 induced tumor cell apoptosis that was insensitive to TP53 status and overexpression of the apoptosis inhibitor BCL2. We show that treatment with b-AP15 inhibited tumor progression in four different in vivo solid tumor models and inhibited organ infiltration in an acute myeloid leukemia model. Our results show that the deubiquitinating activity of the 19S regulatory particle is a new anticancer drug target.