USP14 Inhibition Regulates Tumorigenesis by Inducing Autophagy in Lung Cancer In Vitro

The ubiquitin–proteasome system is an essential regulator of several cellular pathways involving oncogenes. Deubiquitination negatively regulates target proteins or substrates linked to both hereditary and sporadic forms of cancer. The deubiquitinating enzyme ubiquitin-specific protease 14 (USP14) is associated with proteasomes where it trims the ubiquitin chain on the substrate. Here, we found that USP14 is highly expressed in patients with lung cancer. We also demonstrated that USP14 inhibitors (IU1-47 and siRNA-USP14) significantly decreased cell proliferation, migration, and invasion in lung cancer. Remarkably, we found that USP14 negatively regulates lung tumorigenesis not only through apoptosis but also through the autophagy pathway. Our findings suggest that USP14 plays a crucial role in lung tumorigenesis and that USP14 inhibitors are potent drugs in lung cancer treatment.

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The nucleolar ubiquitin-specific protease USP36 deubiquitinates and stabilizes c-Myc

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1411713112 ◽

2015 ◽

Vol 112 (12) ◽

pp. 3734-3739 ◽

Cited By ~ 68

Author(s):

Xiao-Xin Sun ◽

Xia He ◽

Li Yin ◽

Masayuki Komada ◽

Rosalie C. Sears ◽

...

Keyword(s):

Ubiquitin Proteasome System ◽

Degradation Pathway ◽

Deubiquitinating Enzyme ◽

Lung Cancers ◽

Specific Protease ◽

Ubiquitin Proteasome ◽

Ubiquitin Specific Protease ◽

Regulatory Loop ◽

F Box Protein

c-Myc protein stability and activity are tightly regulated by the ubiquitin-proteasome system. Aberrant stabilization of c-Myc contributes to many human cancers. c-Myc is ubiquitinated by SCFFbw7 (a SKP1-cullin-1-F-box complex that contains the F-box and WD repeat domain-containing 7, Fbw7, as the F-box protein) and several other ubiquitin ligases, whereas it is deubiquitinated and stabilized by ubiquitin-specific protease (USP) 28. The bulk of c-Myc degradation appears to occur in the nucleolus. However, whether c-Myc is regulated by deubiquitination in the nucleolus is not known. Here, we report that the nucleolar deubiquitinating enzyme USP36 is a novel c-Myc deubiquitinase. USP36 interacts with and deubiquitinates c-Myc in cells and in vitro, leading to the stabilization of c-Myc. This USP36 regulation of c-Myc occurs in the nucleolus. Interestingly, USP36 interacts with the nucleolar Fbw7γ but not the nucleoplasmic Fbw7α. However, it abolished c-Myc degradation mediated both by Fbw7γ and by Fbw7α. Consistently, knockdown of USP36 reduces the levels of c-Myc and suppresses cell proliferation. We further show that USP36 itself is a c-Myc target gene, suggesting that USP36 and c-Myc form a positive feedback regulatory loop. High expression levels of USP36 are found in a subset of human breast and lung cancers. Altogether, these results identified USP36 as a crucial and bono fide deubiquitinating enzyme controlling c-Myc’s nucleolar degradation pathway.

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Phosphorylation and activation of ubiquitin-specific protease-14 by Akt regulates the ubiquitin-proteasome system

eLife ◽

10.7554/elife.10510 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 55

Author(s):

Daichao Xu ◽

Bing Shan ◽

Byung-Hoon Lee ◽

Kezhou Zhu ◽

Tao Zhang ◽

...

Keyword(s):

Growth Factors ◽

Intracellular Signaling ◽

Ubiquitin Proteasome System ◽

Specific Protein ◽

Negative Control ◽

Common Mechanism ◽

Wide Range ◽

Specific Protease ◽

Ubiquitin Proteasome

Regulation of ubiquitin-proteasome system (UPS), which controls the turnover of short-lived proteins in eukaryotic cells, is critical in maintaining cellular proteostasis. Here we show that USP14, a major deubiquitinating enzyme that regulates the UPS, is a substrate of Akt, a serine/threonine-specific protein kinase critical in mediating intracellular signaling transducer for growth factors. We report that Akt-mediated phosphorylation of USP14 at Ser432, which normally blocks its catalytic site in the inactive conformation, activates its deubiquitinating activity in vitro and in cells. We also demonstrate that phosphorylation of USP14 is critical for Akt to regulate proteasome activity and consequently global protein degradation. Since Akt can be activated by a wide range of growth factors and is under negative control by phosphoinosotide phosphatase PTEN, we suggest that regulation of UPS by Akt-mediated phosphorylation of USP14 may provide a common mechanism for growth factors to control global proteostasis and for promoting tumorigenesis in PTEN-negative cancer cells.

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Ubiquitin-specific Protease 7 Is a Regulator of Ubiquitin-conjugating Enzyme UbE2E1

Journal of Biological Chemistry ◽

10.1074/jbc.m113.469262 ◽

2013 ◽

Vol 288 (23) ◽

pp. 16975-16985 ◽

Cited By ~ 27

Author(s):

Feroz Sarkari ◽

Keith Wheaton ◽

Anthony La Delfa ◽

Majda Mohamed ◽

Faryal Shaikh ◽

...

Keyword(s):

Dynamic Balance ◽

Ubiquitin Proteasome System ◽

Binding Motif ◽

Deubiquitinating Enzyme ◽

Interacting Protein ◽

Identical Manner ◽

Specific Protease ◽

Ubiquitin Specific Protease

Ubiquitin-specific protease 7 (USP7) is a deubiquitinating enzyme found in all eukaryotes that catalyzes the removal of ubiquitin from specific target proteins. Here, we report that UbE2E1, an E2 ubiquitin conjugation enzyme with a unique N-terminal extension, is a novel USP7-interacting protein. USP7 forms a complex with UbE2E1 in vitro and in vivo through the ASTS USP7 binding motif within its N-terminal extension in an identical manner with other known USP7 binding proteins. We show that USP7 attenuates UbE2E1-mediated ubiquitination, an effect that requires the N-terminal ASTS sequence of UbE2E1 as well as the catalytic activity of USP7. Additionally, USP7 is critical in maintaining the steady state levels of UbE2E1 in cells. This study reveals a new cellular mechanism that couples the opposing activities of the ubiquitination machinery and a deubiquitinating enzyme to maintain and modulate the dynamic balance of the ubiquitin-proteasome system.

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A specific E3 ligase/deubiquitinase pair modulates TBP protein levels during muscle differentiation

eLife ◽

10.7554/elife.08536 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 20

Author(s):

Li Li ◽

Silvia Sanchez Martinez ◽

Wenxin Hu ◽

Zhe Liu ◽

Robert Tjian

Keyword(s):

E3 Ligase ◽

Ubiquitin Proteasome System ◽

Central Component ◽

Deubiquitinating Enzyme ◽

Protein Levels ◽

Promoter Recognition ◽

Biochemical Fractionation ◽

Ubiquitin Proteasome ◽

Fine Tune

TFIID—a complex of TATA-binding protein (TBP) and TBP-associated factors (TAFs)—is a central component of the Pol II promoter recognition apparatus. Recent studies have revealed significant downregulation of TFIID subunits in terminally differentiated myocytes, hepatocytes and adipocytes. Here, we report that TBP protein levels are tightly regulated by the ubiquitin-proteasome system. Using an in vitro ubiquitination assay coupled with biochemical fractionation, we identified Huwe1 as an E3 ligase targeting TBP for K48-linked ubiquitination and proteasome-mediated degradation. Upregulation of Huwe1 expression during myogenesis induces TBP degradation and myotube differentiation. We found that Huwe1 activity on TBP is antagonized by the deubiquitinase USP10, which protects TBP from degradation. Thus, modulating the levels of both Huwe1 and USP10 appears to fine-tune the requisite degradation of TBP during myogenesis. Together, our study unmasks a previously unknown interplay between an E3 ligase and a deubiquitinating enzyme regulating TBP levels during cellular differentiation.

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Breakdown of Filamentous Myofibrils by the UPS–Step by Step

Biomolecules ◽

10.3390/biom11010110 ◽

2021 ◽

Vol 11 (1) ◽

pp. 110

Author(s):

Dina Aweida ◽

Shenhav Cohen

Keyword(s):

Protein Quality ◽

Protein Structures ◽

Ubiquitin Proteasome System ◽

Surface Proteins ◽

Catalytic Core ◽

Complex Protein ◽

Ubiquitin Proteasome ◽

Aaa Atpases

Protein degradation maintains cellular integrity by regulating virtually all biological processes, whereas impaired proteolysis perturbs protein quality control, and often leads to human disease. Two major proteolytic systems are responsible for protein breakdown in all cells: autophagy, which facilitates the loss of organelles, protein aggregates, and cell surface proteins; and the ubiquitin-proteasome system (UPS), which promotes degradation of mainly soluble proteins. Recent findings indicate that more complex protein structures, such as filamentous assemblies, which are not accessible to the catalytic core of the proteasome in vitro, can be efficiently degraded by this proteolytic machinery in systemic catabolic states in vivo. Mechanisms that loosen the filamentous structure seem to be activated first, hence increasing the accessibility of protein constituents to the UPS. In this review, we will discuss the mechanisms underlying the disassembly and loss of the intricate insoluble filamentous myofibrils, which are responsible for muscle contraction, and whose degradation by the UPS causes weakness and disability in aging and disease. Several lines of evidence indicate that myofibril breakdown occurs in a strictly ordered and controlled manner, and the function of AAA-ATPases is crucial for their disassembly and loss.

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Circular RNA FLNA acts as a sponge of miR-486-3p in promoting lung cancer progression via regulating XRCC1 and CYP1A1

Cancer Gene Therapy ◽

10.1038/s41417-021-00293-w ◽

2021 ◽

Author(s):

Jiongwei Pan ◽

Gang Huang ◽

Zhangyong Yin ◽

Xiaoping Cai ◽

Enhui Gong ◽

...

Keyword(s):

Lung Cancer ◽

Cancer Cells ◽

Cancer Cell ◽

Cancer Progression ◽

Lung Cancer Cells ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Related Factors

AbstractSignificantly high-expressed circFLNA has been found in various cancer cell lines, but not in lung cancer. Therefore, this study aimed to explore the role of circFLNA in the progression of lung cancer. The target gene of circFLNA was determined by bioinformatics and luciferase reporter assay. Viability, proliferation, migration, and invasion of the transfected cells were detected by CCK-8, colony formation, wound-healing, and transwell assays, respectively. A mouse subcutaneous xenotransplanted tumor model was established, and the expressions of circFLNA, miR-486-3p, XRCC1, CYP1A1, and related genes in the cancer cells and tissues were detected by RT-qPCR, Western blot, or immunohistochemistry. The current study found that miR-486-3p was low-expressed in lung cancer. MiR-486-3p, which has been found to target XRCC1 and CYP1A1, was regulated by circFLNA. CircFLNA was located in the cytoplasm and had a high expression in lung cancer cells. Cancer cell viability, proliferation, migration, and invasion were promoted by overexpressed circFLNA, XRCC1, and CYP1A1 but inhibited by miR-486-3p mimic and circFLNA knockdown. The weight of the xenotransplanted tumor was increased by circFLNA overexpression yet reduced by miR-486-3p mimic. Furthermore, miR-486-3p mimic reversed the effect of circFLNA overexpression on promoting lung cancer cells and tumors and regulating the expressions of miR-486-3p, XRCC1, CYP1A1, and metastasis/apoptosis/proliferation-related factors. However, overexpressed XRCC1 and CYP1A1 reversed the inhibitory effect of miR-486-3p mimic on cancer cells and tumors. In conclusion, circFLNA acted as a sponge of miR-486-3p to promote the proliferation, migration, and invasion of lung cancer cells in vitro and in vivo by regulating XRCC1 and CYP1A1.

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Homeobox-A13 acts as a functional prognostic and diagnostic biomarker via regulating P53 and Wnt signaling pathways in lung cancer

Cancer Biomarkers ◽

10.3233/cbm-200540 ◽

2021 ◽

pp. 1-16

Author(s):

Yang Wang ◽

Bo He ◽

Yan Dong ◽

Gong-Jin He ◽

Xiao-Wei Qi ◽

...

Keyword(s):

Lung Cancer ◽

Signaling Pathways ◽

Cox Regression ◽

Prognostic Significance ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Clinical Feature ◽

Diagnostic Biomarker

BACKGROUND: The prognosis of lung cancer patients is poor without useful prognostic and diagnostic biomarker. To search for novel prognostic and diagnostic markers, we previously found homeobox-A13 (HOXA13) as a promising candidate in lung cancer. OBJECTIVE: To determine the precisely clinical feature, prognostic and diagnostic value, possible role and mechanism of HOXA13. METHODS: Gene-expression was explored by real-time quantitative-PCR, western-blot and tissue-microarray. The associations were analyzed by Chi-square test, Kaplan-Meier and Cox-regression. The roles and mechanisms were evaluated by MTS, EdU, transwell, xenograft tumor and luciferase-reporter assays. RESULTS: HOXA13 expression is increased in tumors, and correlated with age of patients. HOXA13 expression is associated with unfavorable overall survival and relapse-free survival of patients in four cohorts. Interestingly, HOXA13 has different prognostic significance in adenocarcinoma (ADC) and squamous-cell carcinoma (SCC), and is a sex- and smoke-related prognostic factor only in ADC. Importantly, HOXA13 can serve as a diagnostic biomarker for lung cancer, especially for SCC. HOXA13 can promote cancer-cell proliferation, migration and invasion in vitro, and facilitate tumorigenicity and tumor metastasis in vivo. HOXA13 acts the oncogenic roles on tumor growth and metastasis by regulating P53 and Wnt/β-catenin signaling activities in lung cancer. CONCLUSIONS: HOXA13 is a new prognostic and diagnostic biomarker associated with P53 and Wnt/β-catenin signaling pathways.

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Role of Ubiquitin Ligases and the Proteasome in Oncogenesis: Novel Targets for Anticancer Therapies

Journal of Clinical Oncology ◽

10.1200/jco.2012.44.0958 ◽

2013 ◽

Vol 31 (9) ◽

pp. 1231-1238 ◽

Cited By ~ 100

Author(s):

Lindsey N. Micel ◽

John J. Tentler ◽

Peter G. Smith ◽

Gail S. Eckhardt

Keyword(s):

Cell Cycle ◽

Anticancer Agents ◽

Cell Cycle Control ◽

Ubiquitin Proteasome System ◽

Cellular Regulation ◽

Ubiquitin Chain ◽

Key Enzyme ◽

Ubiquitin Proteasome ◽

Enzyme Families ◽

And Function

The ubiquitin proteasome system (UPS) regulates the ubiquitination, and thus degradation and turnover, of many proteins vital to cellular regulation and function. The UPS comprises a sequential series of enzymatic processes using four key enzyme families: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-carrier proteins), E3 (ubiquitin-protein ligases), and E4 (ubiquitin chain assembly factors). Because the UPS is a crucial regulator of the cell cycle, and abnormal cell-cycle control can lead to oncogenesis, aberrancies within the UPS pathway can result in a malignant cellular phenotype and thus has become an attractive target for novel anticancer agents. This article will provide an overall review of the mechanics of the UPS, describe aberrancies leading to cancer, and give an overview of current drug therapies selectively targeting the UPS.

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A Yeast-Based Functional Assay to Study Plant N-Degron – N-Recognin Interactions

Frontiers in Plant Science ◽

10.3389/fpls.2021.806129 ◽

2022 ◽

Vol 12 ◽

Author(s):

Aida Kozlic ◽

Nikola Winter ◽

Theresia Telser ◽

Jakob Reimann ◽

Katrin Rose ◽

...

Keyword(s):

Ubiquitin Proteasome System ◽

Functional Assay ◽

The Novel ◽

In Planta ◽

Amino Terminal ◽

Weak Binding ◽

Ubiquitin Conjugating Enzyme ◽

Ubiquitin Proteasome ◽

The Stability

The N-degron pathway is a branch of the ubiquitin-proteasome system where amino-terminal residues serve as degradation signals. In a synthetic biology approach, we expressed ubiquitin ligase PRT6 and ubiquitin conjugating enzyme 2 (AtUBC2) from Arabidopsis thaliana in a Saccharomyces cerevisiae strain with mutation in its endogenous N-degron pathway. The two enzymes re-constitute part of the plant N-degron pathway and were probed by monitoring the stability of co-expressed GFP-linked plant proteins starting with Arginine N-degrons. The novel assay allows for straightforward analysis, whereas in vitro interaction assays often do not allow detection of the weak binding of N-degron recognizing ubiquitin ligases to their substrates, and in planta testing is usually complex and time-consuming.

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RPNs Levels are Prognostic and Diagnostic Markers for Hepatocellular Carcinoma

10.21203/rs.3.rs-1071357/v1 ◽

2021 ◽

Author(s):

Wangyang zheng ◽

Yuling Zheng ◽

Xue Bai ◽

Yongxu Zhou ◽

Liang Yu ◽

...

Keyword(s):

Western Blot ◽

Cell Lines ◽

Mammalian Cells ◽

Tumor Grade ◽

Ubiquitin Proteasome System ◽

Functional Enrichment ◽

Migration And Invasion ◽

Regulatory Subunits ◽

Hcc Cells

Abstract Background: Ribophorin family (RPNs) are important regulatory subunits of the proteasome. By influencing Ubiquitin-proteasome system activity, RPNs are responsible for almost all processes of physiology and pathology of mammalian cells. Nevertheless, little is known about the role of RPNs in HCC.Methods: In this work, using the online databases Oncomine, UCSC, Kaplan-Meier Plotter, UALCAN, cBioPortal, TIMER2, GeneMANIA,and STRING, we first evaluated the expression, diagnostic, prognostic, genetic alteration, immunity, gene network, and functional enrichment of RPNs in HCC. QPCR and western blot were used to detect RPN6 and RPN9 expressions in HCC tissues and cell lines. Then we performed studies to eveulated their functions in HCC cells proliferation, migration, and invasion in vitro. Results: All RPNs were surprisingly consistently upregulated in HCC tissues. Moreover, RPNs expression pattern is correlated with HCC tumor grade. RPN2, RPN3, RPN6, RPN9, RPN10, RPN11, and RPN12 have robust values in HCC diagnose. Then, survival analysis revealed that high expression of RPN1, RPN2, RPN4, RPN5, RPN6, RPN9, and RPN11were correlated with unfavorable HCC overall survival. Functional enrichment for RPNs, indicated that RPNs have many potential biosynthesis activities expert for UPS functions. Western blot, and qRT-PCR further verified these results in HCC tissues and cell lines. The silencing of RPN6 and RPN9 significantly influenced HCC cells' proliferation, migration, and invasion in vitro.Conclusions: RPN families functions as an important oncogene in HCC. RPN6 and RPN9 have the potential to be potential biomarkers and targets for HCC.

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