Ubiquitin carboxyl-terminal hydrolases: involvement in cancer progression and clinical implications

The role of seven tumor-associated autoantibodies in the diagnosis, staging and treatment guidance of lung cancer

BACKGROUND

This study assessed the diagnosis, staging and treatment guidance of lung cancer (LC) based on seven tumor-associated autoantibodies (TAAbs) -p53, PGP9.5, SOX2, GBU4-5, MAGE A1, CAGE, and GAGE7.

METHODS

ELISA was used to determine the TAAb serum levels in 433 patients diagnosed with LC (161 surgical patients) and 76 patients with benign lung disease (16 surgical patients). The statistical characteristic of the TAAbs was compared among patients with different clinicopathological features. Pre- to postoperative changes in TAAb levels were analyzed to determine their value of LC.

RESULTS

Among all patients, the positive rate of the seven TAAbs was 23.4%, sensitivity was 26.3%, accuracy was 36.3%, specificity was 93.4%, positive predictive value was 95.8%, and negative predictive value was 18.2%; the positive rate for the LC group (26.3%) was significantly higher than that for the benign group (6.6%; P < 0.001). Significant differences in the positive rate of the seven autoantibodies according to age (P < 0.001), smoking history (P = 0.009) and clinical LC stage (P < 0.001) were found. Smoking was positively associated with the positive of TAAbs (Τ = 0.118, P = 0.008). The positive rates of the seven TAAbs for squamous carcinoma (54.5%), other pathological types (44.4%) and poorly differentiated LC (57.1%) were significantly higher than those for the other types. The positive rate of GBU4-5 was highest among all TAAbs, and the SOX2 level in stage III-IV patients was much higher than that in other stages. For patients undergoing surgery, compared with the preoperative levels, the postoperative levels of the 7 markers, particularly p53 (P = 0.027), PGP9.5 (P = 0.007), GAGE7 (P = 0.014), and GBU4-5 (P = 0.002), were significantly different in the malignant group, especially in stage I-II patients, while no clear pre- to postoperative difference was observed in the benign group.

CONCLUSIONS

When the seven TAAbs was positive, it was very helpful for the diagnosis of LC. The 7 TAAbs was valuable for staging and guiding treatment of LC in surgical patients.

PTMs of PD-1/PD-L1 and PROTACs application for improving cancer immunotherapy

Immunotherapy has been developed, which harnesses and enhances the innate powers of the immune system to fight disease, particularly cancer. PD-1 (programmed death-1) and PD-L1 (programmed death ligand-1) are key components in the regulation of the immune system, particularly in the context of cancer immunotherapy. PD-1 and PD-L1 are regulated by PTMs, including phosphorylation, ubiquitination, deubiquitination, acetylation, palmitoylation and glycosylation. PROTACs (Proteolysis Targeting Chimeras) are a type of new drug design technology. They are specifically engineered molecules that target specific proteins within a cell for degradation. PROTACs have been designed and demonstrated their inhibitory activity against the PD-1/PD-L1 pathway, and showed their ability to degrade PD-1/PD-L1 proteins. In this review, we describe how PROTACs target PD-1 and PD-L1 proteins to improve the efficacy of immunotherapy. PROTACs could be a novel strategy to combine with radiotherapy, chemotherapy and immunotherapy for cancer patients.

Deciphering roles of protein post-translational modifications in IgA nephropathy progression and potential therapy

Immunoglobulin A nephropathy (IgAN), one type of glomerulonephritis, displays the accumulation of glycosylated IgA in the mesangium. Studies have demonstrated that both genetics and epigenetics play a pivotal role in the occurrence and progression of IgAN. Post-translational modification (PTM) has been revealed to critically participate in IgAN development and progression because PTM dysregulation results in impaired degradation of proteins that regulate IgAN pathogenesis. A growing number of studies identify that PTMs, including sialylation, o-glycosylation, galactosylation, phosphorylation, ubiquitination and deubiquitination, modulate the initiation and progression of IgAN. Hence, in this review, we discuss the functions and mechanisms of PTMs in regulation of IgAN. Moreover, we outline numerous compounds that govern PTMs and attenuate IgAN progression. Targeting PTMs might be a useful strategy to ameliorate IgAN.

Differences on the level of hepatic transcriptome between two flatfish species in response to liver cancer and environmental pollution levels

Environmental factors can cause cancer in both wild animals and humans. In ecological settings, genetic variation and natural selection can sometimes produce resilience to the negative impacts of environmental change. An increase in oncogenic substances in natural habitats has therefore, unintentionally, created opportunities for using polluted habitats to study cancer defence mechanisms. The Baltic and North Sea are among the most contaminated marine areas, with a long history of pollution. Two flatfish species (flounder, Platichthys flesus and dab, Limanda limanda) are used as ecotoxicological indicator species due to pollution-induced liver cancer. Cancer is more prevalent in dab, suggesting species-specific differences in vulnerability and/or defence mechanisms. We conducted gene expression analyses for 30 flatfishes. We characterize between- and within-species patterns in potential cancer-related mechanisms. By comparing cancerous and healthy fishes, and non-cancerous fishes from clean and polluted sites, we suggest also genes and related physiological mechanisms that could contribute to a higher resistance to pollution-induced cancer in flounders. We discovered changes in transcriptome related to elevated pollutant metabolism, alongside greater tumour suppression mechanisms in the liver tissue of flounders compared to dabs. This suggests either hormetic upregulation of tumour suppression or a stronger natural selection pressure for higher cancer resistance for flounders in polluted environment. Based on gene expression patterns seen in cancerous and healthy fish, for liver cancer to develop in flounders, genetic defence mechanisms need to be suppressed, while in dabs, analogous process is weak or absent. We conclude that wild species could offer novel insights and ideas for understanding the nature and evolution of natural cancer defence mechanisms.

E3 ubiquitin ligases and deubiquitinases in bladder cancer tumorigenesis and implications for immunotherapies

With the rapidly increasing incidence of bladder cancer in China and worldwide, great efforts have been made to understand the detailed mechanism of bladder cancer tumorigenesis. Recently, the introduction of immune checkpoint inhibitor-based immunotherapy has changed the treatment strategy for bladder cancer, especially for advanced bladder cancer, and has improved the survival of patients. The ubiquitin-proteasome system, which affects many biological processes, plays an important role in bladder cancer. Several E3 ubiquitin ligases and deubiquitinases target immune checkpoints, either directly or indirectly. In this review, we summarize the recent progress in E3 ubiquitin ligases and deubiquitinases in bladder cancer tumorigenesis and further highlight the implications for bladder cancer immunotherapies.

UCHL1 aggravates skin fibrosis through an IGF-1-induced Akt/mTOR/HIF-1α pathway in keloid

Keloid is a heterogeneous disease featured by the excessive production of extracellular matrix. It is a great challenge for both clinicians and patients regarding the exaggerated and uncontrolled outgrowth and the therapeutic resistance of the disease. In this study, we verified that UCHL1 was drastically upregulated in keloid fibroblasts. UCHL1 had no effects on cell proliferation and migration, but instead promoted collagen I and α-SMA expression that was inhibited by silencing UCHL1 gene and by adding in LDN-57444, a pharmacological inhibitor for UCHL1 activity as well. The pathological process was mediated by IGF-1 promoted Akt/mTOR/HIF-1α signaling pathway because inhibition of any of them could reduce the expression of collagen I and α-SMA driven by UCHL1 in fibroblasts. Also, we found that UCHL1 expression in keloid fibroblasts was promoted by M2 macrophages via TGF-β1. These findings extend our understanding of the pathogenesis of keloid and provide potential therapeutic targets for the disease.

Identifying a dynamic transcriptomic landscape of the cynomolgus macaque placenta during pregnancy at single-cell resolution

Supporting healthy pregnancy outcomes requires a comprehensive understanding of the cellular hierarchy and underlying molecular mechanisms in the primate placenta during gestation. Here, we present a single-cell transcriptome-wide view of the cynomolgus macaque placenta throughout gestation. Bioinformatics analyses and multiple validation experiments suggested that placental trophoblast cells exhibited stage-specific differences across gestation. Interactions between trophoblast cells and decidual cells also showed gestational stage-dependent differences. The trajectories of the villous core cells indicated that placental mesenchymal cells were derived from extraembryonic mesoderm (ExE.Meso) 1, whereas placental Hofbauer cells, erythrocytes, and endothelial cells were derived from ExE.Meso2. Comparative analyses of human and macaque placentas uncovered conserved features of placentation across species, and the discrepancies of extravillous trophoblast cells (EVTs) between human and macaque correlated to their differences in invasion patterns and maternal-fetal interactions. Our study provides a groundwork for elucidating the cellular basis of primate placentation.

Farrerol directly activates the deubiqutinase UCHL3 to promote DNA repair and reprogramming when mediated by somatic cell nuclear transfer

Farrerol, a natural flavanone, promotes homologous recombination (HR) repair to improve genome-editing efficiency, but the specific protein that farrerol directly targets to regulate HR repair and the underlying molecular mechanisms have not been determined. Here, we find that the deubiquitinase UCHL3 is the direct target of farrerol. Mechanistically, farrerol enhanced the deubiquitinase activity of UCHL3 to promote RAD51 deubiquitination, thereby improving HR repair. Importantly, we find that embryos of somatic cell nuclear transfer (SCNT) exhibited defective HR repair, increased genomic instability and aneuploidy, and that the farrerol treatment post nuclear transfer enhances HR repair, restores transcriptional and epigenetic network, and promotes SCNT embryo development. Ablating UCHL3 significantly attenuates farrerol-mediated stimulation in HR and SCNT embryo development. In summary, we identify farrerol as an activator of the deubiquitinase UCHL3, highlighted the importance of HR and epigenetic changes in SCNT reprogramming and provide a feasible method to promote SCNT efficiency.

UCHL3 promotes hepatocellular carcinoma cell migration by de-ubiquitinating and stabilizing Vimentin

Background

Hepatocellular carcinoma (HCC) is a common malignant tumor associated with a poor prognosis. Ubiquitin carboxyl-terminal hydrolase L3 (UCHL3) has been reported to promote diverse tumors, but little is known about its role in HCC.

Methods

Expression levels of UCHL3 in Huh7 and Hep3B cells were measured by qRT-PCR. UCHL3, Vimentin protein levels, and ubiquitination levels were determined by Western blot assay. co-immunoprecipitation, Immunofluorescence, and IHC were used to detect the interaction and expression association between UCHL3 and Vimentin in the cells. Wound healing and Transwell assays were used to measure cell migration. Spheroid formation assay were used to assess stem-like properties.

Results

UCHL3 expression was found to be significantly elevated in HCC and associated with poor prognosis. UCHL3 promoted migration and stem-like properties of HCC cells. Vimentin was identified as a potential de-ubiquitination substrate of UCHL3 and UCHL3 interacted with and promoted the de-ubiquitination of Vimentin, enhancing its stability. Moreover, the suppression of UCHL3 by siRNA or the inhibition by TCID upregulated ubiquitinated Vimentin. Vimentin attenuated the suppression of cell migration caused by knockdown of UCHL3.

Conclusion

UCHL3 was highly expressed in HCC and functioned as an oncogene. Vimentin is a novel substrate of UCHL3 and its stabilization and de-ubiquitination enhanced HCC cell migration.

A Novel Subgroup of UCHL1-Related Cancers Is Associated with Genomic Instability and Sensitivity to DNA-Damaging Treatment

PURPOSE

Identification of molecularly-defined cancer subgroups and targeting tumor-specific vulnerabilities have a strong potential to improve treatment response and patient outcomes but remain an unmet challenge of high clinical relevance, especially in head and neck squamous cell carcinoma (HNSC).

EXPERIMENTAL DESIGN

We established a UCHL1-related gene set to identify and molecularly characterize a UCHL1-related subgroup within TCGA-HNSC by integrative analysis of multi-omics data. An extreme gradient boosting model was trained on TCGA-HNSC based on GSVA scores for gene sets of the MSigDB to robustly predict UCHL1-related cancers in other solid tumors and cancer cell lines derived thereof. Potential vulnerabilities of UCHL1-related cancer cells were elucidated by an in-silico drug screening approach.

RESULTS

We established a 497-gene set, which stratified the TCGA-HNSC cohort into distinct subgroups with a UCHL1-related or other phenotype. UCHL1-related HNSC were characterized by higher frequencies of genomic alterations, which was also evident for UCHL1-related cancers of other solid tumors predicted by the classification model. These data indicated an impaired maintenance of genomic integrity and vulnerability for DNA-damaging treatment, which was supported by a favorable prognosis of UCHL1-related tumors after radiotherapy, and a higher sensitivity of UCHL1-related cancer cells to irradiation or DNA-damaging compounds (e.g., Oxaliplatin).

CONCLUSION

Our study established UCHL1-related cancers as a novel subgroup across most solid tumor entities with a unique molecular phenotype and DNA-damaging treatment as a specific vulnerability, which requires further proof-of-concept in pre-clinical models and future clinical trials.

Ubiquitin C‑terminal hydrolase‑L1: A new cancer marker and therapeutic target with dual effects (Review)

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), a member of the lesser-known deubiquitinating enzyme family, has deubiquitinase and ubiquitin (Ub) ligase activity and the role of stabilizing Ub. UCH-L1 was first discovered in the brain and is associated with regulating cell differentiation, proliferation, transcriptional regulation and numerous other biological processes. UCH-L1 is predominantly expressed in the brain and serves a role in tumor promotion or inhibition. There is still controversy about the effect of UCH-L1 dysregulation in cancer and its mechanisms are unknown. Extensive research to investigate the mechanism of UCH-L1 in different types of cancer is key for the future treatment of UCH-L1-associated cancer. The present review details the molecular structure and function of UCH-L1. The role of UCH-L1 in different types of cancer is also summarized and how novel treatment targets provide a theoretical foundation in cancer research is discussed.

Improvement in the performance of an autoantibody panel in combination with heat shock protein 90a for the detection of early‑stage lung cancer

The early diagnosis of lung cancer is closely associated with the decline of mortality. A panel consisting of seven lung cancer-related autoantibodies (7-AABs) has been shown to be a reliable and specific indicator for the early detection of lung cancer, with a specificity of ~90% and a positive predictive value of ~85%. However, its low sensitivity and negative predictive value limit its wide application. To improve its diagnostic value, the diagnostic efficiencies of 7-AABs in combination with non-specific tumor markers were retrospectively investigated for the detection of early-stage lung cancer. A total of 217 patients with small lung nodules who presented with ground-glass opacity or solid nodules as well as 30 healthy controls were studied. The concentrations of 7-AABs and heat shock protein 90a (HSP90a) were assessed using ELISA. Automated flow fluorescence immune analysis was used for the assessment of CEA, CYFRA21-1, CA199 and CA125 levels. The results showed that 7-AABs + HSP90a possessed a remarkably improved diagnostic efficiency for patients with small pulmonary nodules or for patients with lung nodules of different types, which suggested that 7-AABs in combination with HSP90a could have a high clinical value for the improvement of the diagnostic efficiency of early-stage lung cancer.

The intricate interplay between HIFs, ROS, and the ubiquitin system in the tumor hypoxic microenvironment

Alterations in protein ubiquitination and hypoxia-inducible factor (HIF) signaling both contribute to tumorigenesis and tumor progression. Ubiquitination is a dynamic process that is coordinately regulated by E3 ligases and deubiquitinases (DUBs), which have emerged as attractive therapeutic targets. HIF expression and transcriptional activity are usually increased in tumors, leading to poor clinical outcomes. Reactive oxygen species (ROS) are upregulated in tumors and have multiple effects on HIF signaling and the ubiquitin system. A growing body of evidence has shown that multiple E3 ligases and UBDs function synergistically to control the expression and activity of HIF, thereby allowing cancer cells to cope with the hypoxic microenvironment. Conversely, several E3 ligases and DUBs are regulated by hypoxia and/or HIF signaling. Hypoxia also induces ROS production, which in turn modulates the stability or activity of HIF, E3 ligases, and DUBs. Understanding the complex networks between E3 ligase, DUBs, ROS, and HIF will provide insights into the fundamental mechanism of the cellular response to hypoxia and help identify novel molecular targets for cancer treatment. We review the current knowledge on the comprehensive relationship between E3 ligase, DUBs, ROS, and HIF signaling, with a particular focus on the use of E3 ligase or DUB inhibitors in cancer.

Updates of Genomics and Proteomics of Parathyroid Carcinoma

Parathyroid carcinoma is a rare disease that needs an additional diagnostic tool and wide therapeutic options. The genomics and proteomics approach may help to find the tools to improve the prognosis of the disease by early detection and metastatic control. The findings from genomics were mainly CDC73, PRUNE2, CCND1, and genes related to PI3K/AKT/mTOR and Wnt pathways. CDC73, PRUNE2, and CCND1 were closely related to each other, and PRUNE2 and CCND1 genes are related to expression levels of parafibromin protein, which may aid in supporting the definite diagnosis of the disease. PI3K/AKT/mTOR and Wnt pathways could be a potential therapeutic target for the disease, which needs further basket trials to prove the concept. In this review, current findings from genomics and proteomics studies in parathyroid carcinoma were reviewed.

UCHL5 Promotes Proliferation and Migration of Bladder Cancer Cells by Activating c-Myc via AKT/mTOR Signaling

Ubiquitin C-terminal hydrolase L5 (UCHL5) is a deubiquitinating enzyme (DUB) that removes ubiquitin from its substrates. Associations between UCHL5 and cancer have been reported in various tissues, but the effect of UCHL5 on bladder cancer has not been thoroughly investigated. This study investigates the expression and function of UCHL5 in bladder cancer. UCHL5 was shown to be abnormally expressed using IHC of tissue microarray and Western blotting. Several procedures were performed to assess the effect of UCHL5 overexpression or knockdown on bladder cancer, such as cell proliferation, colony formation, wound-healing, and Transwell assays. In addition, RNA-Seq and Western blotting experiments were used to verify the status of downstream signaling pathways. Finally, bladder cancers with knockdown or overexpression of UCHL5 were treated with either SC79 or LY294002 to examine the participation of the AKT/mTOR signaling pathway and the expression of downstream targets c-Myc, SLC25A19, and ICAM5. In contrast to adjacent tissue samples, we discovered that UCHL5 was substantially expressed in bladder cancer samples. We also found that UCHL5 downregulation significantly suppressed both tumor growth in vivo and cell proliferation and migration in vitro. According to RNA-Seq analyses and Western blotting experiments, the expression of c-Myc, SLC25A19, and ICAM5 was modified as a result of UCHL5 activating AKT/mTOR signaling in bladder cancer cells. All things considered, our findings show that increased UCHL5 expression stimulates AKT/mTOR signaling, subsequently triggering the expression of c-Myc, SLC25A19, and ICAM5, which in turn promotes carcinogenesis in bladder cancer. UCHL5 is therefore a potential target for therapy in bladder cancer patients.

Neurodegenerative Disorder Risk in Krabbe Disease Carriers

Krabbe disease (KD) is a rare autosomal recessive disorder caused by mutations in the galactocerebrosidase gene (GALC). Defective GALC causes aberrant metabolism of galactolipids present almost exclusively in myelin, with consequent demyelinization and neurodegeneration of the central and peripheral nervous system (NS). KD shares some similar features with other neuropathies and heterozygous carriers of GALC mutations are emerging with an increased risk in developing NS disorders. In this work, we set out to identify possible variations in the proteomic profile of KD-carrier brain to identify altered pathways that may imbalance its homeostasis and that may be associated with neurological disorders. The differential analysis performed on whole brains from 33-day-old twitcher (galc ^−/−), heterozygous (galc ^+/−), and wild-type mice highlighted the dysregulation of several multifunctional factors in both heterozygous and twitcher mice. Notably, the KD-carrier mouse, despite its normal phenotype, presents the deregulation of vimentin, receptor of activated protein C kinase 1 (RACK1), myelin basic protein (MBP), 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNP), transitional endoplasmic reticulum ATPase (VCP), and N-myc downstream regulated gene 1 protein (NDRG1) as well as changes in the ubiquitinated-protein pattern. Our findings suggest the carrier may be affected by dysfunctions classically associated with neurodegeneration: (i) alteration of (mechano) signaling and intracellular trafficking, (ii) a generalized affection of proteostasis and lipid metabolism, with possible defects in myelin composition and turnover, and (iii) mitochondrion and energy supply dysfunctions.

Ubiquitin C-terminal hydrolase L1 (UCHL1), a double-edged sword in mammalian oocyte maturation and spermatogenesis

BACKGROUND

Recent studies have shown that ubiquitin-mediated cell apoptosis can modulate protein interaction and involve in the progress of oocyte maturation and spermatogenesis. As one of the key regulators involved in ubiquitin signal, ubiquitin C-terminal hydrolase L1 (UCHL1) is considered a molecular marker associated with spermatogonia stem cells. However, the function of UCHL1 was wildly reported to regulate various bioecological processes, such as Parkinson's disease, lung cancer, breast cancer and colon cancer, how UCHL1 affects the mammalian reproductive system remains an open question.

METHODS

We identified papers through electronic searches of PubMed database from inception to July 2022.

RESULTS

Here, we summarize the important function of UCHL1 in controlling mammalian oocyte development, regulating spermatogenesis and inhibiting polyspermy, and we posit the balance of UCHL1 was essential to maintaining reproductive cellular and tissue homeostasis.

CONCLUSION

This study considers the 'double-edged sword' role of UCHL1 during gametogenesis and presents new insights into UCHL1 in germ cells.

Research Progress of DUB Enzyme in Hepatocellular Carcinoma

According to GLOBOCAN 2021 cancer incidence and mortality statistics compiled by the International Agency for Research on Cancer, hepatocellular carcinoma (HCC) is the most common malignancy in the human liver and one of the leading causes of cancer death worldwide. Although there have been great advances in the treatment of HCC, such as regofenib, sorafenib, and lomvatinib, which have been developed and approved for the clinical treatment of advanced or metastatic HCC. However, they only prolong survival by a few months, and patients with advanced liver cancer are susceptible to tumor invasion metastasis and drug resistance. Ubiquitination modification is a type of post-translational modification of proteins. It can affect the physiological activity of cells by regulating the localization, stability and activity of proteins, such as: gene transcription, DNA damage signaling and other pathways. The reversible process of ubiquitination is called de-ubiquitination: it is the process of re-releasing ubiquitinated substrates with the participation of de-ubiquitinases (DUBs) and other active substances. There is growing evidence that many dysregulations of DUBs are associated with tumorigenesis. Although dysregulation of deuquitinase function is often found in HCC and other cancers, The mechanisms of action of many DUBs in HCC have not been elucidated. In this review, we focused on several deubiquitinases (DUBs) associated with hepatocellular carcinoma, including their structure, function, and relationship to hepatocellular carcinoma. hepatocellular carcinoma was highlighted, as well as the latest research reports. Among them, we focus on the USP family and OTU family which are more studied in the HCC. In addition, we discussed the prospects and significance of targeting DUBs as a new strategy for the treatment of hepatocellular carcinoma. It also briefly summarizes the research progress of some DUB-related small molecule inhibitors and their clinical application significance as a treatment for HCC in the future.

USP35 is a Potential Immunosuppressive Factor in Skin Cutaneous Melanoma

Background

As one of the most immunogenic malignancies, skin cutaneous melanoma (SKCM) is mainly characterized by a high prevalence in immune-compromised patients and a brisk lymphocyte infiltration in the tumor microenvironment (TME). However, to date, studies on deubiquitination in SKCM are still very limited.

Methods

Public data with regard to this study in SKCM patients were acquired from The Cancer Genome Atlas (TCGA) and the Gene-Expression Omnibus (GEO) databases. We stratified TCGA-SKCM cases using consensus clustering and identified independent prognostic factors in deubiquitinating enzymes encoding genes (DECGs) by LASSO-Cox analysis. USP35 transcriptome level was examined using public data and validated by Immunohistochemical (IHC) staining at the protein level. Enrichment analysis was used to explore the potential functions of USP35, and the TISCH database, providing further evidence at the single-cell level. The CIBERSORT algorithm was used to assess the relationship between USP35 and the immune microenvironment, and IHC was used to further evaluate the relationship between USP35 and immunotherapy response. Finally, we used the cBioPortal and the Methsurv database to analyze the significance of genomic alterations of USP35 in melanoma.

Results

Our results showed that DECGs can be effectively used to stratify SKCM patients, suggesting their potential significance in the development of SKCM. Furthermore, USP35 overexpression was significantly associated with an unfavorable prognosis. We further revealed that USP35 may be involved in the activation of TORC1 signaling. Most importantly, USP35 was found to be significantly associated with an immunosuppressive TME, both in terms of negative correlation with the abundance of infiltrating CD8+ T cells and in terms of the fact that patients with high USP35 expression may benefit less from immunotherapy than those with low USP35 expression.

Conclusion

Deubiquitinating enzymes are of great importance in the diagnosis and treatment of SKCM, and USP35 is an extremely promising target for immunotherapy.

UCHL1 promotes proliferation and metastasis in head and neck squamous cell carcinoma and could be a potential therapeutic target

OBJECTIVE

The purpose of this study was to research the physiological roles of ubiquitin carboxyl-terminal esterase L1 (UCHL1) in head and neck squamous cell carcinoma (HNSCC).

STUDY DESIGN

Ten HNSCC samples and matched normal oral mucosal tissues were collected. UCHL1 expression of these tissues was detected by the immunohistochemical staining and real-time quantitative polymerase chain reaction. The human HNSCC cell line HN6 UCHL1 knockout (UCHL1 KO) cell line was constructed using CRISPR/CAS9 gene editing and verified by western blotting. Wound healing assay, cell proliferation assay, cell invasion assay, and flow cytometric analysis of the cell cycle and apoptosis were applied to research the role of UCHL1 in HNSCC. Also, an RNAseq gene expression data set and HNSCC patient survival data from The Cancer Genome Atlas were analyzed.

RESULTS

UCHL1 was highly expressed in HNSCC tissues compared with normal oral mucosal tissues (P = .032). A decreased proliferation (P < .0001), migration (P < .0001), and invasion (P = .0049) ability of HN6 cells was exhibited after knockout of UCHL1. However, HN6 UCHL1 KO cells showed no significant differences in the cell cycle or apoptosis. The progression, nodal metastasis status, and stage of HNSCC had a positive correlation with the expression of UCHL1.

CONCLUSIONS

UCHL1 plays an important role in HNSCC, and we consider that targeting UCHL1 may be a feasible therapeutic strategy for HNSCC.

Inhibiting UCH-L5: Rational Design of a Cyclic Ubiquitin-Based Peptide Inhibitor

The ubiquitin-proteasome system is an essential regulator of many cellular processes including controlling protein homeostasis. The degradation of proteins by the multi-subunit proteasome complex is tightly regulated through a series of checkpoints, amongst which are a set of deubiquitinating proteases (DUBs). The proteasome-associated DUBs, UCH-L5 (Ubiquitin carboxyl-terminal hydrolase isozyme L5) and USP14 (Ubiquitin-specific protease 14), and the integral-DUB in the proteasome, Rpn11, is known to regulate proteasomal degradation by deubiquitination of distinct substrates. Although selective inhibitors for USP14 and Rpn11 have been recently developed, there are no known inhibitors that selectively bind to UCH-L5. The X-ray structure of the Ubiquitin (Ub) bound to UCH-L5 shows a β-sheet hairpin in Ub that contains a crucial hydrophobic patch involved in the interaction with UCH-L5. Herein, we designed and developed both a Ub sequence-based linear- and cyclic- β-sheet hairpin peptide that was found to preferably inhibit UCH-L5. We show that these peptides have low micromolar IC₅₀ values and the cyclic peptide competes with the activity-based UbVME (Ubiquitin-Vinyl-Methyl-Ester) probe for UCH-L5, binding in a concentration-dependent manner. We further establish the selectivity profile of the cyclic peptide for UCH-L5 compared to other members of the UCH-DUB family and other cysteine DUBs in cell lysate. Furthermore, the cyclic peptide infiltrated cells resulting in the accumulation of polyUb chains, and was found to be non-toxic at the concentrations used here. Taken together, our data suggest that the cyclic peptide permeates the cell membrane, inhibits UCH-L5 by possibly blocking its deubiquitinating function, and contributes to the accumulation of polyubiquitinated substrates. The implications of inhibiting UCH-L5 in the context of the 26S proteasome render it an attractive candidate for further development as a potential selective inhibitor for therapeutic purposes.

Efficacy of autoantibodies combined with tumor markers in the detection of lung cancer

BACKGROUND

The purpose of this study was to explore the detection value of seven autoantibodies (TAAbs): p53, PGP9.5, SOX2, GBU4-5, MAGE A1, CAGE, and GAGE7 and three tumor markers: CYFRA21-1, NSE, and SCCA in the diagnosis of lung cancer.

METHODS

ELISA was used to detect the levels of the TAAbs, and chemiluminescence immunoassay was used to test the levels of the tumor markers. The diagnostic efficacy of the TAAbs combined with the tumor markers for lung cancer was evaluated by receiver operating characteristic (ROC) curves.

RESULTS

The positive rate of the combined detection of seven TAAbs and three tumor markers in lung cancer (37.8%) was higher than that in other three groups. The positive rates of SOX2, GAGE7, MAGE A1, CAGE, CYFRA21-1, and SCCA had differences among the four groups. Compared with the benign lung disease group, only GAGE7, CYFRA21-1, and SCCA differed among the groups. The combined sensitivity of the TAAbs was 29.07% (AUC, 0.594), the combined sensitivity of all the markers was 37.76% (AUC, 0.660 [p < 0.05]), and Youden's index was 0.196. In the lung cancer group, CYFRA21-1 had a significant difference in age and sex, and SOX2, MAGE A1, CYFRA21-1, NSE, and SCCA were significantly different in pathological type and TNM. In contrast, p53 and GBU4-5 showed no significant differences in age, sex, pathological type, and TNM.

CONCLUSIONS

The combined detection of seven TAAbs and three tumor markers could be useful in early diagnosis of lung cancer.

UCHL1 acts as a potential oncogene and affects sensitivity of common anti-tumor drugs in lung adenocarcinoma

Background

Lung adenocarcinoma is the leading cause of cancer death worldwide. Recently, ubiquitin C-terminal hydrolase L1 (UCHL1) has been demonstrated to be highly expressed in many tumors and plays the role of an oncogene. However, the functional mechanism of UCHL1 is unclear in lung adenocarcinoma progression.

Methods

We analyzed the differential expression of the UCHL1 gene in lung adenocarcinoma and normal lung tissues, and the correlation between the UCHL1 gene and prognosis was also analyzed by the bioinformatics database TCGA. Meanwhile, we detected and analyzed the expression of UCHL1 and Ki-67 protein in a tissue microarray (TMA) containing 150 patients with lung adenocarcinoma by immunohistochemistry (IHC) and clinicopathological characteristics by TCGA database. In vitro experiments, we knocked down the UCHL1 gene of A549 cells and detected the changes in cell migration, invasion, and apoptosis. At the same time, we analyzed the effect of UCHL1 on anti-tumor drug sensitivity of lung adenocarcinoma by a bioinformatics database. In terms of the detection rate of lung adenocarcinoma indicators, we analyzed the impact of UCHL1 combined with common clinical indicators on the detection rate of lung adenocarcinoma through a bioinformatics database.

Results

In this study, the analysis of UCHL1 protein expression in lung adenocarcinoma proved that obviously higher UCHL1 protein level was discovered in lung adenocarcinoma tissues. The expression of UCHL1 was closely related to poor clinical outcomes. Interestingly, a significantly positive correlation between the expression of UCHL1 and Ki-67-indicated UCHL1 was associated with tumor migration and invasion. Through executing loss of function tests, we affirmed that silencing of UCHL1 expression significantly inhibited migration and invasion of lung adenocarcinoma cells in vitro. Furthermore, lung adenocarcinoma cells with silenced UCHL1 showed a higher probability of apoptosis. In terms of the detection rate of lung adenocarcinoma indicators, we discovered UCHL1 could improve the detection rate of clinical lung adenocarcinoma and affect drug sensitivity.

Conclusion

In lung adenocarcinoma, UCHL1 promotes tumor migration, invasion, and metastasis by inhibiting apoptosis and has an important impact on the clinical drug treatment of lung adenocarcinoma. In addition, UCHL1 can improve the detection rate of clinical lung adenocarcinoma. Above all, UCHL1 may be a new marker for the diagnosis of lung adenocarcinoma and provide a new target for the treatment of clinical diseases.

Ribonucleotide reductase holoenzyme inhibitor COH29 interacts with deubiquitinase ubiquitin-specific protease 2 and downregulates its substrate protein cyclin D1

USP2 contributes to the quality control of multiple oncogenic proteins including cyclin D1, Mdm2, Aurora-A, etc., and it is a potential target for anti-cancer drug development. However, currently only a few inhibitors with moderate inhibition activities against USP2 have been discovered. USP2-targeted active compounds with either new scaffolds or enhanced activities are in need. Here in this study, Ub-AMC hydrolysis assay-based screening against ~4000 commercially available drugs and drug candidates was performed to identify USP2-targeted inhibitors. COH29, which was originally developed as an anti-cancer agent by blocking the function of human ribonucleotide reductase (RNR, IC₅₀  = 16 µM), was found to exhibit an inhibition activity against USP2 with the IC₅₀ value at 2.02 ± 0.16 µM. The following conducted biophysical and biochemical experiments demonstrated that COH29 could specifically interact with USP2 and inhibit its enzymatic activity in a noncompetitive inhibition mode (K_i  = 1.73 ± 0.14 µM). Since COH29 shows similar inhibitory potencies against RNR (RRM2) and USP2, USP2 inhibition-dependent cellular consequences of COH29 are expected. The results of cellular assays confirmed that the application of COH29 could downregulate the level of cyclin D1 by enhancing its degradation via ubiquitin-proteasome system (UPS), and the modulation effect of COH29 on cyclin D1 is independent of RRM2. Since cyclin D1 acts as an oncogenic driver in human cancer, our findings suggest that USP2 might be a promising therapeutic target for cyclin D1-addicted cancers, and COH29 could serve as a starting compound for high selectivity inhibitor development against USP2.

UCHL5 controls β-catenin destruction complex function through Axin1 regulation

Wnt/β-catenin signaling is crucially involved in many biological processes, from embryogenesis to cancer development. Hence, the complete understanding of its molecular mechanism has been the biggest challenge in the Wnt research field. Here, we identified ubiquitin C-terminal hydrolase like 5 (UCHL5), a deubiquitinating enzyme, as a novel negative regulator of Wnt signaling, upstream of β-catenin. The study further revealed that UCHL5 plays an important role in the β-catenin destruction complex, as it physically interacts with multiple domains of Axin1 protein. Our functional analyses also elucidated that UCHL5 is required for both the stabilization and the polymerization of Axin1 proteins. Interestingly, although these events are governed by deubiquitination in the DIX domain of Axin1 protein, they do not require the deubiquitinating activity of UCHL5. The study proposes a novel molecular mechanism of UCHL5 potentiating the functional activity of Axin1, a scaffolder of the β-catenin destruction complex.

Imaging-Based Screening of Deubiquitinating Proteases Identifies Otubain-1 as a Stabilizer of c-MYC

The ubiquitin-proteasome pathway precisely controls the turnover of transcription factors in the nucleus, playing an important role in maintaining appropriate quantities of these regulatory proteins. The transcription factor c-MYC is essential for normal development and is a critical cancer driver. Despite being highly expressed in several tissues and malignancies, the c-MYC protein is also continuously targeted by the ubiquitin-proteasome pathway, which can either facilitate or inhibit c-MYC degradation. Deubiquitinating proteases can remove ubiquitin chains from target proteins and rescue them from proteasomal digestion. This study sought to determine novel elements of the ubiquitin-proteasome pathway that regulate c-MYC levels. We performed an overexpression screen with 41 human proteases to identify which deubiquitinases stabilize c-MYC. We discovered that the highly expressed Otubain-1 (OTUB1) protease increases c-MYC protein levels. Confirming its role in enhancing c-MYC activity, we found that elevated OTUB1 correlates with inferior clinical outcomes in the c-MYC-dependent cancer multiple myeloma, and overexpression of OTUB1 accelerates the growth of myeloma cells. In summary, our study identifies OTUB1 as a novel amplifier of the proto-oncogene c-MYC.

UCH-L3 structure and function: Insights about a promising drug target

In the past few years, researchers have shed light on the immense importance of ubiquitin in numerous regulatory pathways. The post-translational addition of mono or poly-ubiquitin molecules namely "ubiquitinoylation" is therefore pivotal to maintain the cell's vitality, maturation, differentiation, and division. Part of conserving homeostasis stems from maintaining the ubiquitin pool in the vicinity of the cell's intracellular environment; this crucial role is played by deubiquitylating enzymes (DUBs) that cleave ubiquitin molecules from target molecules. To date, they are categorized into 7 families with ubiquitin carboxyl c-terminal de-hydrolase family (UCH) as the most common and well-studied. Ubiquitin C-terminal hydrolase L (UCH-L3) is a significant protein in this family as it has been implicated in many molecular and cellular processes with its mRNA identified in a range of body tissues including the brain. It goes without saying that it manifests in maintaining health and when abnormally regulated in disease. As it is an attractive small molecule drug target, scientists have used high throughput screening (HTS) and other drug discovery methods to discover inhibitors for this enzyme for the treatment of cancer and neurodegenerative diseases. In this review we present an overview of UCH-L3 catalytic mechanism, structure, its role in DNA repair and cancer along with the inhibitors discovered so far to halt its activity.

Parathyroid Carcinoma and Adenoma Co-existing in One Patient: Case Report and Comparative Proteomic Analysis

BACKGROUND/AIM

The lack of specific parathyroid carcinoma (PC) biomarkers in clinical practice points out the importance of analyzing the proteomic signature of this cancer. We performed a comparative proteomic analysis of PC and parathyroid adenoma (PA) co-existing in the same patient.

PATIENTS AND METHODS

PC and PA were taken from a 63-year-old patient. Using two-dimensional differential gel electrophoresis (2D-DIGE) coupled to mass spectrometry we examined the differences between PC and PA proteins. For validation, additional PC and PA samples were obtained from 10 patients. Western blot analysis was used to validate the difference of expression observed with 2D-DIGE analysis. Bioinfomatic analysis was performed using QIAGEN's Ingenuity Pathways Analysis (IPA) to determine the predominant canonical pathways and interaction networks involved.

RESULTS

Thirty-three differentially expressed proteins were identified in PC compared to PA. Among these, ubiquitin C-terminal hydrolase-L1 (UCH-L1) was highly overexpressed in PC. The result was confirmed by Western Blot analysis in additional PC samples.

CONCLUSION

Our comparative proteomic analysis of co-existing neoplasms allowed detecting specific and peculiar differences between PC and PA overcoming population biological variability.

MAFG-AS1/MAFG positive feedback loop contributes to cisplatin resistance in bladder urothelial carcinoma through antagonistic ferroptosis

Though promoting ferroptosis can reduce cisplatin resistance in tumor cells, ferroptosis and cisplatin resistance in bladder urothelial carcinoma (BUC) following long non-coding RNAs (lncRNAs) is largely unknown. Here, we found the highly expressed lncRNA MAF transcription factor G antisense RNA 1 (MAFG-AS1) in BUC, and its inhibition increased the sensitivity of BUC cells to cisplatin by promoting ferroptosis. Mechanically, binding to iron chaperone poly(rC)-binding protein 2 (PCBP2) facilitated the recruitments of MAFG-AS1 to deubiquitinase ubiquitin carboxyl-terminal hydrolase isozyme L5 (UCHL5), thus stabilizing PCBP2 protein itself. Then PCBP2 was confirmed to interact with ferroportin 1 (FPN1), an iron export protein, leading to inhibition of ferroptosis. Moreover, the expression of MAFG-AS1 was regulated by the transcriptional factor MAFG. Interestingly, MAFG-AS1 stimulated MAFG transcription by recruiting histone acetyltransferase p300 (EP300) to promote the histone 3 at lysine 27 (H3K27ac) at genomic locus of MAFG, forming a MAFG-AS1/MAFG positive feedback loop. In patient samples, higher expression of MAFG-AS1 and MAFG in BUC tissues was significantly correlated with T status and N status, such that MAFG-AS1, MAFG, and the combination of the two were independent prognostic indicators and chemotherapy sensitivity predictive biomarkers for BUC patients. These findings suggest that inhibition of MAFG-AS1 and MAFG can increase the sensitivity of BUC cells to cisplatin through promoting ferroptosis, indicating the novel chemotherapy sensitivity biomarkers and therapeutic target for BUC.

Application of SPRi Biosensors for Determination of 20S Proteasome and UCH-L1 Levels in the Serum and Urine of Transitional Bladder Cancer Patients

The ubiquitin–proteasome system (UPS) participates in the degradation of proteins which play an important role in regulating the cell cycle, apoptosis, and angiogenesis, as well as in the immune system. These processes are important in carcinogenesis. Transitional cell carcinoma (TCC) is one of the predominant types of bladder cancer. The relationship between the ubiquitin–proteasome system and cancer progression has become a topic of increasing interest among researchers. In this work, we propose an application of surface plasmon resonance imaging (SPRi)-based biosensors for the detection of 20S proteasome and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) in the blood serum and urine of patients with TCC. The aim of the study was to determine 20S proteasome and UCH-L1 concentrations and to correlate the results with clinicopathological parameters. The group of subjects consisted of 82 patients with confirmed TCC, in addition to a control group of 27 healthy volunteers. It was found that 20S proteasome and UCH-L1 concentrations were significantly elevated in both the serum and urine of TCC patients, compared with the healthy subjects. There was a correlation between 20S proteasome concentrations in serum and urine, as well as between serum proteasome and UCH-L1 concentration. The SPRi biosensor sensitive to 20S proteasome using PSI inhibitor as the receptor, and the SPRi biosensor sensitive to the UCH-L1 protein using the protein-specific antibody as the receptor is suitable for the determination of 20S proteasome and UCH-L1 in body fluids and can serve as useful tools in the investigation of cancer biomarkers.

Serum glial fibrillary acidic protein is a predictor of brain metastases in patients with metastatic breast cancer

In patients with metastatic breast cancer (MBC), brain metastases (BM) are associated with high morbidity and mortality. However, there is no validated serum biomarker that accurately predicts BM occurrence in these patients, and the role of serum biomarkers for prognosis remains unclear. Here, we evaluated the association of neurofilament light chain (NfL), ubiquitin C-terminal hydrolase L1 (UCHL1), glial fibrillary acidic protein (GFAP) and tau serum levels with BM presence and prognosis in patients with MBC. In serum samples from patients with MBC with (n = 100) and without BM (n = 47), we measured the biomarker serum levels using single molecule array (Simoa) technology (Neurology-4-Plex assay). To evaluate their accuracy to identify patients with BM, we determined the receiver operating characteristic curve and the area under the curve (AUC) for each biomarker and calculated their sensitivity and specificity. The median serum levels of NfL, UCHL1, tau and GFAP were significantly higher in patients with BM. The AUC for GFAP (0.82, 95% confidence interval [CI] 0.75-0.88) was significantly higher than those of the other biomarkers considered independently. Using the medians as cutoff values, elevated serum levels of NfL, UCHL1, tau and GFAP were associated with BM in univariate analysis, but only high GFAP levels in multivariate analysis (odd ratio 23.4, 95% CI 6.8-80.5, P < .001). Elevated serum GFAP levels were independently associated with poor outcome. GFAP outperforms NfL, UCHL1 and tau as diagnostic and prognostic factor of BM in patients with MBC. These results must now be validated in an independent cohort of patients.

Small-Molecule Inhibitors Targeting Proteasome-Associated Deubiquitinases

The 26S proteasome is the principal protease for regulated intracellular proteolysis. This multi-subunit complex is also pivotal for clearance of harmful proteins that are produced throughout the lifetime of eukaryotes. Recent structural and kinetic studies have revealed a multitude of conformational states of the proteasome in substrate-free and substrate-engaged forms. These conformational transitions demonstrate that proteasome is a highly dynamic machinery during substrate processing that can be also controlled by a number of proteasome-associated factors. Essentially, three distinct family of deubiquitinases–USP14, RPN11, and UCH37–are associated with the 19S regulatory particle of human proteasome. USP14 and UCH37 are capable of editing ubiquitin conjugates during the process of their dynamic engagement into the proteasome prior to the catalytic commitment. In contrast, RPN11-mediated deubiquitination is directly coupled to substrate degradation by sensing the proteasome’s conformational switch into the commitment steps. Therefore, proteasome-bound deubiquitinases are likely to tailor the degradation events in accordance with substrate processing steps and for dynamic proteolysis outcomes. Recent chemical screening efforts have yielded highly selective small-molecule inhibitors for targeting proteasomal deubiquitinases, such as USP14 and RPN11. USP14 inhibitors, IU1 and its progeny, were found to promote the degradation of a subset of substrates probably by overriding USP14-imposed checkpoint on the proteasome. On the other hand, capzimin, a RPN11 inhibitor, stabilized the proteasome substrates and showed the anti-proliferative effects on cancer cells. It is highly conceivable that these specific inhibitors will aid to dissect the role of each deubiquitinase on the proteasome. Moreover, customized targeting of proteasome-associated deubiquitinases may also provide versatile therapeutic strategies for induced or repressed protein degradation depending on proteolytic demand and cellular context.

Spectroscopic investigations, concentration dependent SERS, and molecular docking studies of a benzoic acid derivative

Spectroscopic analysis, density functional theory (DFT) studies and surface enhanced Raman scattering of 4-((3-bromo-5-chloro-2-hydroxybenzylidene)amino)benzoic acid (BCHB) have been studied on different silver colloids concentrations in order to know the particular chemical species responsible for the spectra. For Raman and surface enhanced Raman scattering (SERS) wavenumbers, changes are observed. Observed variations in the modes of ring may be due to interaction of the π-electrons and presence of this indicated that RingII is more inclined than RingI and the BCHB assumes inclined orientation for concentration 10^-3 M. Changes in orientation are seen in SERS spectra depending on concentration. In order to determine the electron-rich and poor sites of BCHB, the molecular electrostatic potential was also constructed. The molecular docking studies show that the bindings and interactions with the receptors may be supporting evidence for further studies in design further BCHB pharmaceutical applications.

Ubiquitin-proteasome system-targeted therapy for uveal melanoma: what is the evidence?

Uveal melanoma (UM) is a rare ocular tumor. The loss of BRCA1-associated protein 1 (BAP1) and the aberrant activation of G protein subunit alpha q (GNAQ)/G protein subunit alpha 11 (GNA11) contribute to the frequent metastasis of UM. Thus far, limited molecular-targeted therapies have been developed for the clinical treatment of UM. However, an increasing number of studies have revealed the close relationship between the ubiquitin proteasome system (UPS) and the malignancy of UM. UPS consists of a three-enzyme cascade, i.e. ubiquitin-activating enzymes (E1s); ubiquitin-conjugating enzymes (E2s); and ubiquitin-protein ligases (E3s), as well as 26S proteasome and deubiquitinases (DUBs), which work coordinately to dictate the fate of intracellular proteins through regulating ubiquitination, thus influencing cell viability. Due to the critical role of UPS in tumors, we here provide an overview of the crosstalk between UPS and the malignancy of UM, discuss the current UPS-targeted therapies in UM and highlight its potential in developing novel regimens for UM.

Ubiquitin Carboxyl-Terminal Hydrolases and Human Malignancies: The Novel Prognostic and Therapeutic Implications for Head and Neck Cancer

Ubiquitin C-terminal hydrolases (UCHs), a subfamily of deubiquitinating enzymes (DUBs), have been found in a variety of tumor entities and play distinct roles in the pathogenesis and development of various cancers including head and neck cancer (HNC). HNC is a heterogeneous disease arising from the mucosal epithelia of the upper aerodigestive tract, including different anatomic sites, distinct histopathologic types, as well as human papillomavirus (HPV)-positive and negative subgroups. Despite advances in multi-disciplinary treatment for HNC, the long-term survival rate of patients with HNC remains low. Emerging evidence has revealed the members of UCHs are associated with the pathogenesis and clinical prognosis of HNC, which highlights the prognostic and therapeutic implications of UCHs for patients with HNC. In this review, we summarize the physiological and pathological functions of the UCHs family, which provides enlightenment of potential mechanisms of UCHs family in HNC pathogenesis and highlights the potential consideration of UCHs as attractive drug targets.

Loss of BAP1 Leads to More YAPing in Pancreatic Cancer

Pancreatic cancer is increasing in incidence and is expected to be the second leading cause of cancer-related mortality by the year 2030. Understanding molecular pathways that contribute to pancreatic cancer initiation and progression provides the opportunity to uncover potential molecular vulnerabilities that can be exploited therapeutically. In this issue of Cancer Research, Lee and colleagues provide compelling evidence that BRCA1-associated protein (BAP1) functions as a tumor suppressor in pancreatic cancer by promoting the activity of the Hippo tumor suppressor pathway, highlighting YAP and TAZ, Hippo effectors, as attractive therapeutic targets in pancreatic ductal adenocarcinoma, especially in BAP1-deficient or low tumors.See related article by Lee et al., p. 1656.

Deubiquitination Reactions on the Proteasome for Proteasome Versatility

The 26S proteasome, a master player in proteolysis, is the most complex and meticulously contextured protease in eukaryotic cells. While capable of hosting thousands of discrete substrates due to the selective recognition of ubiquitin tags, this protease complex is also dynamically checked through diverse regulatory mechanisms. The proteasome's versatility ensures precise control over active proteolysis, yet prevents runaway or futile degradation of many essential cellular proteins. Among the multi-layered processes regulating the proteasome's proteolysis, deubiquitination reactions are prominent because they not only recycle ubiquitins, but also impose a critical checkpoint for substrate degradation on the proteasome. Of note, three distinct classes of deubiquitinating enzymes-USP14, RPN11, and UCH37-are associated with the 19S subunits of the human proteasome. Recent biochemical and structural studies suggest that these enzymes exert dynamic influence over proteasome output with limited redundancy, and at times act in opposition. Such distinct activities occur spatially on the proteasome, temporally through substrate processing, and differentially for ubiquitin topology. Therefore, deubiquitinating enzymes on the proteasome may fine-tune the degradation depending on various cellular contexts and for dynamic proteolysis outcomes. Given that the proteasome is among the most important drug targets, the biology of proteasome-associated deubiquitination should be further elucidated for its potential targeting in human diseases.

The Role of Deubiquitinating Enzymes in Acute Lung Injury and Acute Respiratory Distress Syndrome

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) are characterized by an inflammatory response, alveolar edema, and hypoxemia. ARDS occurs most often in the settings of pneumonia, sepsis, aspiration of gastric contents, or severe trauma. The prevalence of ARDS is approximately 10% in patients of intensive care. There is no effective remedy with mortality high at 30-40%. Most functional proteins are dynamic and stringently governed by ubiquitin proteasomal degradation. Protein ubiquitination is reversible, the covalently attached monoubiquitin or polyubiquitin moieties within the targeted protein can be removed by a group of enzymes called deubiquitinating enzymes (DUBs). Deubiquitination plays an important role in the pathobiology of ALI/ARDS as it regulates proteins critical in engagement of the alveolo-capillary barrier and in the inflammatory response. In this review, we provide an overview of how DUBs emerge in pathogen-induced pulmonary inflammation and related aspects in ALI/ARDS. Better understanding of deubiquitination-relatedsignaling may lead to novel therapeutic approaches by targeting specific elements of the deubiquitination pathways.

UCH-L3 promotes non-small cell lung cancer proliferation via accelerating cell cycle and inhibiting cell apoptosis

Ubiquitin C-terminal hydrolase-L3 (UCH-L3) is a deubiquitinase that has a crucial role in oncogenesis. This study was aimed to explore the biological function of UCH-L3 in non-small cell lung cancer (NSCLC). Bioinformatics analysis was used to detect UCH-L3 expression in NSCLC tissues and normal lung tissues, and to analyze the relationship between UCH-L3 expression and survival of patients. qRT-PCR and western blotting assays were used to detect UCH-L3 expression in NSCLC tumor tissues and adjacent normal tissues. CCK-8 assay was performed to examine the effect of UCH-L3 on NSCLC cell proliferation. Flow cytometry assay was conducted to examine the effect of UCH-L3 on NSCLC cell cycle and apoptosis. The expression of UCH-L3 in NSCLC tissues was markedly higher than in normal lung tissues, and high expression of UCH-L3 was positively associated with the poor survival of patients. UCH-L3 knockdown significantly inhibited the proliferation of NSCLC cells, whereas UCH-L3 overexpression had the opposite effect. Moreover, UCH-L3 promoted NSCLC cells proliferation via accelerating cell cycle and inhibiting cell apoptosis. UCH-L3 is upregulated in NSCLC and positively associated with the poor survival, and its expression contributes to NSCLC cell proliferation by accelerating cell cycle and inhibiting cell apoptosis.

BAP1 functions as a tumor promoter in prostate cancer cells through EMT regulation

BRCA1-associated protein 1 (BAP1) is a deubiquitinating enzyme that has long been considered to be a tumor suppressor in various tumors, including renal cell carcinoma, uveal melanoma, mesothelioma, and cutaneous melanoma. However, the involvement of BAP1 in the progression of prostate cancer has not been studied until recently. Herein, we investigated the tumor promoting function of BAP1 in the context of prostate cancer. Analysis of The Cancer Genome Atlas (TCGA) data set showed that prostate cancer patients express high levels of BAP1 mRNA. High BAP1 expression is inversely correlated with disease-free survival in patients with prostate cancer. Among the prostate cell lines tested, BAP1 expression was high in tumorigenic and metastatic cell lines, but was low in normal prostate cell line. Knockdown of BAP1 in PC3 or DU145 cells induced mesenchymal-to-epithelial transition (MET). Further, BAP1-knockdown resulted in decreased migration and invasion of PC3 and DU145 cells. Conversely, overexpression of BAP1 in RWPE1, a normal prostate cell line, induced the migratory and invasive properties. Collectively, our findings identified that BAP1 has a tumor promoting function in prostate cancer cells, and suggest that BAP1 can serve as a potential therapeutic target for prostate cancer.

LncRNA DRAIC inhibits proliferation and metastasis of gastric cancer cells through interfering with NFRKB deubiquitination mediated by UCHL5

Background

Long non-coding RNA (lncRNA) as a widespread and pivotal epigenetic molecule participates in the occurrence and progression of malignant tumors. DRAIC, a kind of lncRNA whose coding gene location is on 15q23 chromatin, has been found to be weakly expressed in a variety of malignant tumors and acts as a suppressor, but its characteristics and role in gastric cancer (GC) remain to be elucidated.

Methods

Sixty-seven primary GC tissues and paired paracancerous normal tissues were collected. Bioinformatics is used to predict the interaction molecules of DRAIC. DRAIC and NFRKB were overexpressed or interfered exogenously in GC cells by lentivirus or transient transfection. Quantitative real-time PCR (qPCR) and western blotting were used to evaluate the expression of DRAIC, UCHL5 and NFRKB. The combinations of DRAIC and NFRKB or UCHL5 and NFRKB were verified by RNA-IP and Co-IP assays. Ubiquitination-IP and the treatment of MG132 and CHX were used to detect the ubiquitylation level of NFRKB. The CCK-8 and transwell invasion and migration assays measured the proliferation, migration and invasion of GC cells.

Results

DRAIC is down-regulated in GC tissues and cell lines while its potential interacting molecules UCHL5 and NFRKB are up-regulated, and DRAIC is positively correlated with NFRKB protein instead of mRNA. Lower DRAIC and higher UCHL5 and NFRKB indicated advanced progression of GC patients. DRAIC could increase NFRKB protein significantly instead of NFRKB mRNA and UCHL5, and bind to UCHL5. DRAIC combined with UCHL5 and attenuated binding of UCHL5 and NFRKB, meanwhile promoting the degradation of NFRKB via ubiquitination, and then inhibited the proliferation and metastasis of GC cells, which can be rescued by oeNFRKB.

Conclusion

DRAIC suppresses GC proliferation and metastasis via interfering with the combination of UCHL5 and NFRKB and mediating ubiquitination degradation.

Ailanthone increases oxidative stress in CDDP-resistant ovarian and bladder cancer cells by inhibiting of Nrf2 and YAP expression through a post-translational mechanism

Chemoresistance represents one of the main obstacles in treating several types of cancer, including bladder and ovarian cancers, and it is characterized by an increase of cellular antioxidant potential. Nrf2 and YAP proteins play an important role in increasing chemoresistance and in inducing antioxidant enzymes. It has been reported that Ailanthone (Aila), a compound extracted from the Ailanthus Altissima, has an anticancer activity toward several cancer cell lines, including chemoresistant cell lines. We have examined the effect of Aila on proliferation, migration and expression of Nrf2 and YAP proteins in A2780 (CDDP-sensitive) and A2780/CP70 (CDDP-resistant) ovarian cancer cells. Furthermore, to clarify the mechanism of Aila action we extended our studies to sensitive and CDDP-resistant 253J-BV bladder cancer cells, which have been used in a previous study on the effect of Aila. Results demonstrated that Aila exerted an inhibitory effect on growth and colony formation of sensitive and CDDP-resistant ovarian cancer cells and reduced oriented cell migration with higher effectiveness in CDDP resistant cells. Moreover, Aila strongly reduced Nrf2 and YAP protein expression and reduced the expression of the Nrf2 target GSTA4, and the YAP/TEAD target survivin. In CDDP-resistant ovarian and bladder cancer cells the intracellular oxidative stress level was lower with respect to the sensitive cells. Moreover, Aila treatment further reduced the superoxide anion content of CDDP-resistant cells in correlation with the reduction of Nrf2 and YAP proteins. However, Aila treatment increased Nrf2 and YAP mRNA expression in all cancer cell lines. The inhibition of proteolysis by MG132, a proteasoma inhibitor, restored Nrf2 and YAP protein expressions, suggesting that the Aila effect was at post-translational level. In accordance with this observation, we found an increase of the Nrf2 inhibitor Keap1, a reduction of p62/SQSTM1, a Nrf2 target which leads Keap1 protein to the autophagic degradation, and a reduction of P-YAP. Moreover, UCHL1 deubiquitinase expression, which was increased in bladder and ovarian resistant cells, was down-regulated by Aila treatment. In conclusion we demonstrated that Aila can reduce proliferation and migration of cancer cells through a mechanism involving a post translational reduction of Nrf2 and YAP proteins which, in turn, entailed an increase of oxidative stress particularly in the chemoresistant lines.

Ubiquitin carboxy-terminal hydrolase L1 - physiology and pathology

Ubiquitin C-terminal hydrolase 1 (UCHL1) is an enzyme unique for its multiple activity - both ligase and hydrolase. UCHL1 was first identified as an abundant protein found in the brain and testes, however its expression is not limited to the neuronal compartment. UCHL1 is also highly expressed in carcinomas of various tissue origins, including those from brain, lung, breast, kidney, colon, prostate, pancreas and mesenchymal tissues. Loss-of-function studies and an inhibitor for UCHL1 confirmed the importance of UCHL1 for cancer therapy. So far biological significance of UCHL1 was described in the following processes: spermatogenesis, oncogenesis, angiogenesis, cell proliferation and differentiation in skeletal muscle, inflammation, tissue injury, neuronal injury and neurodegeneration.

Genetic Base of Behavioral Disorders in Mucopolysaccharidoses: Transcriptomic Studies

Mucopolysaccharidoses (MPS) are a group of inherited metabolic diseases caused by mutations leading to defective degradation of glycosaminoglycans (GAGs) and their accumulation in cells. Among 11 known types and subtypes of MPS, neuronopathy occurs in seven (MPS I, II, IIIA, IIIB, IIIC, IIID, VII). Brain dysfunctions, occurring in these seven types/subtypes include various behavioral disorders. Intriguingly, behavioral symptoms are significantly different between patients suffering from various MPS types. Molecular base of such differences remains unknown. Here, we asked if expression of genes considered as connected to behavior (based on Gene Ontology, GO terms) is changed in MPS. Using cell lines of all MPS types, we have performed transcriptomic (RNA-seq) studies and assessed expression of genes involved in behavior. We found significant differences between MPS types in this regard, with the most severe changes in MPS IIIA (the type considered as the behaviorally most severely affected), while the lowest changes in MPS IVA and MPS VI (types in which little or no behavioral disorders are known). Intriguingly, relatively severe changes were found also in MPS IVB (in which, despite no behavioral disorder noted, the same gene is mutated as in GM1 gangliosidosis, a severe neurodegenerative disease) and MPS IX (in which only a few patients were described to date, thus, behavioral problems are not well recognized). More detailed analyses of expression of certain genes allowed us to propose an association of specific changes in the levels of transcripts in specific MPS types to certain behavioral disorders observed in patients. Therefore, this work provides a principle for further studies on the molecular mechanism of behavioral changes occurring in MPS patients.

Protein Deimination and Extracellular Vesicle Profiles in Antarctic Seabirds

Pelagic seabirds are amongst the most threatened of all avian groups. They face a range of immunological challenges which seem destined to increase due to environmental changes in their breeding and foraging habitats, affecting prey resources and exposure to pollution and pathogens. Therefore, the identification of biomarkers for the assessment of their health status is of considerable importance. Peptidylarginine deiminases (PADs) post-translationally convert arginine into citrulline in target proteins in an irreversible manner. PAD-mediated deimination can cause structural and functional changes in target proteins, allowing for protein moonlighting in physiological and pathophysiological processes. PADs furthermore contribute to the release of extracellular vesicles (EVs), which play important roles in cellular communication. In the present study, post-translationally deiminated protein and EV profiles of plasma were assessed in eight seabird species from the Antarctic, representing two avian orders: Procellariiformes (albatrosses and petrels) and Charadriiformes (waders, auks, gulls and skuas). We report some differences between the species assessed, with the narrowest EV profiles of 50-200 nm in the northern giant petrel Macronectes halli, and the highest abundance of larger 250-500 nm EVs in the brown skua Stercorarius antarcticus. The seabird EVs were positive for phylogenetically conserved EV markers and showed characteristic EV morphology. Post-translational deimination was identified in a range of key plasma proteins critical for immune response and metabolic pathways in three of the bird species under study; the wandering albatross Diomedea exulans, south polar skua Stercorarius maccormicki and northern giant petrel. Some differences in Gene Ontology (GO) biological and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for deiminated proteins were observed between these three species. This indicates that target proteins for deimination may differ, potentially contributing to a range of physiological functions relating to metabolism and immune response, as well as to key defence mechanisms. PAD protein homologues were identified in the seabird plasma by Western blotting via cross-reaction with human PAD antibodies, at an expected 75 kDa size. This is the first study to profile EVs and to identify deiminated proteins as putative novel plasma biomarkers in Antarctic seabirds. These biomarkers may be further refined to become useful indicators of physiological and immunological status in seabirds-many of which are globally threatened.

The role of deubiquitinating enzymes in gastric cancer

The epigenetic regulation of gene expression (via DNA methylation, histone modification and microRNA interference) contributes to a variety of diseases, particularly cancer. Protein deubiquitination serves a key role in the mechanism underlying histone modification, and consequently influences tumor development and progression. Improved characterization of the role of ubiquitinating enzymes has led to the identification of numerous deubiquitinating enzymes (DUBs) with various functions. Gastric cancer (GC) is a highly prevalent cancer type that exhibits a high mortality rate. Latest analysis about cancer patient revealed that GC is sixth deadliest cancer type, which frequently occur in male (7.2%) than female (4.1%). Complex associations between DUBs and GC progression have been revealed in multiple studies; however, the molecular mechanism underpinning the metastasis and recurrence of GC is yet to be elucidated. Generally, DUBs were upregulated in gastric cancer. The relation of DUBs and tumor size, classification and staging was observed in GC. Besides, 5-yar survival rate of patients with GC is effeccted by expression level of DUBs. Among the highly expressed DUBs, specifically six DUBs namely UCHs, USPs, OTUs, MJDs, JAMMs and MCPIPs effect on this survival rate. Consequently, the association between GC and DUBs has received increasing attention in recent years. Therefore, in the present review, literature investigating the association between DUBs and GC pathophysiology was analyzed and critically appraised.

Inhibition of UCHL1 by LDN-57444 attenuates Ang II-Induced atrial fibrillation in mice

Atrial fibrillation (AF) is the most common human arrhythmia in clinical practice and may be promoted by atrial inflammation and fibrosis. Ubiquitination is an important posttranslational modification process that is reversed by deubiquitinating enzymes (DUBs). DUBs play critical roles in modulating the degradation, activity, trafficking, and recycling of substrates. However, less research has focused on the role of DUBs in AF. Here, we investigated the effect of ubiquitin C-terminal hydrolase 1 (UCHL1), an important DUB, on the development of AF induced by angiotensin II (Ang II). Male wild-type mice were treated with the UCHL1 inhibitor LDN57444 (LDN) at a dose of 40 μg/kg and infused with Ang II (2000 ng/kg/min) for 3 weeks. Our results showed that Ang II-infused wild-type (WT) mice had higher systolic blood pressure and an increased incidence and duration of AF. Conversely, this effect was attenuated in LDN-treated mice. Moreover, the administration of LDN significantly reduced Ang II-induced left atrial dilation, fibrosis, inflammatory cell infiltration, and reactive oxygen species (ROS) production. Mechanistically, LDN treatment inhibited the activation of multiple signaling pathways (the AKT, ERK1/2, HIF-1α, and TGF-β/smad2/3 pathways) and the expression of CX43 protein in atrial tissues compared with that in vehicle-treated control mice. Overall, our study identified UCHL1 as a novel regulator that contributes to Ang II-induced AF and suggests that the administration of LDN may represent a potential therapeutic approach for treating hypertensive AF.

Emerging role of ubiquitin-specific protease 14 in oncogenesis and development of tumor: Therapeutic implication

Ubiquitin (Ub) is a small protein that can be attached to substrate proteins to direct their degradation via the proteasome. Deubiquitinating enzymes (DUBs) reverse this process by removing ubiquitin from its substrate protein. Over the past few decades, ubiquitin-specific protease 14 (USP14), a member of the DUBs, has emerged as an important player in various types of cancers. In this article, we review and summarize biological function of USP14 in tumorigenesis and multiple signaling pathways. To determine its role in cancer, we analyzed USP14 gene expression across a panel of tumors, and discussed that it could serve as a novel bio-marker in several types of cancer. And recent contributions indicated that USP14 has been shown to act as a tumor-promoting gene via the AKT, NF-κB, MAPK pathways etc. Besides, drugs targeting USP14 have shown potential anti-tumor effect and clinical significance. We focus on recent studies that explore the link between USP14 and cancer, and further discuss USP14 as a novel target for cancer therapy.

The role of DUBs in the post-translational control of cell migration

Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.