Association of clinicopathological features with UbcH10 expression in colorectal cancer

Comprehensive analysis of the prognosis and tumor immune microenvironment of ubiquitin-conjugating enzyme transport-related gene UBE2C in hepatocellular carcinoma

Ubiquitin-conjugating enzyme E2 C (UBE2C) is involved in tumor progression and cellular processes in many cancers and is implicated in cell cycle regulation. However, its prognostic significance in Hepatocellular carcinoma (HCC) and the mechanism of tumor immune response are unknown. The expression of UBE2C genes in HCC and normal tissue samples was investigated based on The Cancer Genome Atlas (TCGA) LIHC dataset and validated by Gene Expression Omnibus and Human Protein Atlas. Subsequently, the relationship between UBE2C gene expression, clinicopathologic parameters, and each survival period was investigated by regression analysis and Kaplan-Meier survival curves. The set of genes co-expressed with UBE2C was constructed and subjected to genomic enrichment analysis, GO and KEGG pathway enrichment analysis. Finally, the relationship between UBE2C gene expression and immune cell infiltration, immunosuppressive molecules in tumor samples from the TCGA-LIHC dataset was investigated. UBE2C gene expression levels were significantly higher in HCC samples compared to normal samples (p < 0.05). Higher UBE2C gene expression was closely associated with higher tumor grade and later tumor stage. The results of Kaplan-Meier survival curves showed that the survival of HCC patients with high UBE2C expression was shorter than that of patients with low UBE2C expression (p < 0.05, HR(CI) = 1.870[1.276, 2.741]). The results of PPI showed a high correlation between cell cycle-related proteins and UBE2C gene expression. Additionally, the highly expressed UBE2C gene was associated with an increased number of immunosuppressive molecules. UBE2C is an independent predictive marker for HCC patients, and the prognostic value of survival is improved when combined with clinical stage information. This study reveals its potential as a prognostic biomarker and as a new target for HCC intervention.

Ubiquitination-Binding Enzyme 2C is Associated with Cancer Development and Prognosis and is a Potential Therapeutic Target

UBE2C (Ubiquitination-binding enzyme 2C), one of the E2 enzymes encoded in the human genome, is a component of the ubiquitin proteasome system and plays a pivotal role in regulating cell cycle progression. Moreover, UBE2C is highly expressed and may play a pivotal role in both high-incidence and high-mortality malignancies, including lung cancers, breast cancers, and esophageal cancers. UBE2C influences a number of key processes, including cell cycle progression, tumor invasion and metastasis, proliferation, and drug resistance. However, few articles have systematically summarized the role of UBE2C in cancer. The aim of this review is to describe the structure and function of UBE2C, focusing on the current status of UBE2C research in malignant tumors. Furthermore, this review presents the potential of UBE2C as a new therapeutic target and a diagnostic and prognostic biomarker. Finally, future research directions for UBE2C are proposed. It is of great value to explore the mechanism of action of UBE2C in the tumor microenvironment (TME). A comprehensive and coherent comprehension of UBE2C will undoubtedly facilitate its transition from fundamental research to clinical applications.

Exploring Potential Epigenetic Biomarkers for Colorectal Cancer Metastasis

Metastatic progression is a complex, multistep process and the leading cause of cancer mortality. There is growing evidence that emphasises the significance of epigenetic modification, specifically DNA methylation and histone modifications, in influencing colorectal (CRC) metastasis. Epigenetic modifications influence the expression of genes involved in various cellular processes, including the pathways associated with metastasis. These modifications could contribute to metastatic progression by enhancing oncogenes and silencing tumour suppressor genes. Moreover, specific epigenetic alterations enable cancer cells to acquire invasive and metastatic characteristics by altering cell adhesion, migration, and invasion-related pathways. Exploring the involvement of DNA methylation and histone modification is crucial for identifying biomarkers that impact cancer prediction for metastasis in CRC. This review provides a summary of the potential epigenetic biomarkers associated with metastasis in CRC, particularly DNA methylation and histone modifications, and examines the pathways associated with these biomarkers.

Metformin inhibits the proliferation and invasion of ovarian cancer cells by suppressing TRIM37-induced TRAF2 ubiquitination

Ovarian cancer is the leading cause of death in gynecological malignancies worldwide. Our previous studies have proved that metformin inhibited the proliferation and invasion of ovarian cancer in vitro and in vivo. However, the underlying mechanisms have not been fully elucidated. Immunohistochemistry was carried out to detect the expression of tripartite motif‐containing 37 (TRIM37), Ki‐67, and MMP‐9 in ovarian cancer and normal tissues. The influence of TRIM37 on the proliferation and invasion of ovarian cancer cells was verified by the real‐time cellular analysis proliferation test, colony formation test, and Transwell assay. Western blot analysis and immunoprecipitation were used to detect the expression of the nuclear factor‐κB (NF‐κB) pathway and the interaction between TRIM37 and tumor necrosis factor receptor‐associated factor 2 (TRAF2). Ubiquitination detection was carried out to detect the ubiquitination level of TRAF2. The present study revealed that TRIM37 expression was significantly increased in ovarian cancer tissues compared with normal control tissues, and its overexpression was closely associated with proliferation and metastasis. Metformin inhibited the NF‐κB signaling pathway by downregulating TRIM37. Metformin also inhibited the ubiquitination of TRAF2 induced by TRIM37 overexpression. Metformin inhibits the proliferation and invasion of ovarian cancer cells by suppressing TRIM37‐induced TRAF2 ubiquitination.

Integrative Bioinformatics Analysis Reveals CHEK1 and UBE2C as Luminal A Breast Cancer Subtype Biomarkers

In light of the limited number of targetable oncogenic drivers in breast cancer (BRCA), it is important to identify effective and druggable gene targets for the treatment of this devastating disease. Herein, the GSE102484 dataset containing expression profiling data from 683 BRCA patients was re-analyzed using weighted gene co-expression network analysis (WGCNA). The yellow module with the highest correlation to BRCA progression was screened out, followed by functional enrichment analysis and establishment of a protein–protein interaction (PPI) network. After further validation through survival analysis and expression evaluation, CHEK1 and UBE2C were finally identified as hub genes related to the progression of BRCA, especially the luminal A breast cancer subtype. Notably, both hub genes were found to be dysregulated in multiple types of immune cells and closely correlated with tumor infiltration, as revealed by Tumor Immune Estimation Resource (TIMER) along with other bioinformatic tools. Construction of transcription factors (TF)-hub gene network further confirmed the existence of 11 TFs which could regulate both hub genes simultaneously. Our present study may facilitate the invention of targeted therapeutic drugs and provide novel insights into the understanding of the mechanism beneath the progression of BRCA.

Ubc1 turnover contributes to the spindle assembly checkpoint in Saccharomyces cerevisiae

The spindle assembly checkpoint protects the integrity of the genome by ensuring that chromosomes are properly attached to the mitotic spindle before they are segregated during anaphase. Activation of the spindle checkpoint results in inhibition of the Anaphase-Promoting Complex (APC), an E3 ubiquitin ligase that triggers the metaphase-anaphase transition. Here, we show that levels of Ubc1, an E2 enzyme that functions in complex with the APC, modulate the response to spindle checkpoint activation in Saccharomyces cerevisiae. Overexpression of Ubc1 increased resistance to microtubule poisons, whereas Ubc1 shut-off sensitized cells. We also found that Ubc1 levels are regulated by the spindle checkpoint. Checkpoint activation or direct APC inhibition led to a decrease in Ubc1 levels, charging, and half-life. Additionally, stabilization of Ubc1 prevented its down-regulation by the spindle checkpoint and increased resistance to checkpoint-activating drugs. These results suggest that down-regulation of Ubc1 in response to spindle checkpoint signaling is necessary for a robust cell cycle arrest.

Comprehensive Pan-Cancer Analysis of the Prognostic and Immunological Roles of the METTL3/lncRNA-SNHG1/miRNA-140-3p/UBE2C Axis

Growing evidence has demonstrated that UBE2C plays a critical role in cancer progression, but there is no study focusing on the prognosis, upstream regulation mechanism, and immunological roles of UBE2C across diverse tumor types. In this study, we found that UBE2C was elevated in this human pan-cancer analysis, and high expression of UBE2C was correlated with poor prognosis. In addition, UBE2C expression was markedly associated with tumor mutation burden (TMB), microsatellite instability (MSI), immune cell infiltration, and diverse drug sensitivities. Finally, we showed that the METTL3/SNHG1/miRNA-140-3p axis could potentially regulate UBE2C expression. N(6)-Methyladenosine (m6A) modifications improved the stability of methylated SNHG1 transcripts by decreasing the rate of RNA degradation, which lead to upregulation of SNHG1 in non-small cell lung cancer (NSCLC). In vitro functional experiments showed that SNHG1, as a competing endogenous RNA, sponges miR-140-3p to increase UBE2C expression in NSCLC cell lines. Our study elucidates the clinical importance and regulatory mechanism of the METTL3/SNHG1/miRNA-140-3p/UBE2C axis in NSCLC and provides a prognostic indicator, as well as a promising therapeutic target for patients with NSCLC.

Dysregulation of the Ubiquitin Proteasome System in Human Malignancies: A Window for Therapeutic Intervention

Simple Summary

The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. Dysregulation of the UPS results in loss of ability to maintain protein quality through proteolysis, and is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss the mechanisms linking dysregulated UPS to human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing clinical trials, are also presented in this review.

Abstract

The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. This process is tightly regulated through the activation and transfer of polyubiquitin chains to target proteins which are then recognized and degraded by the 26S proteasome complex. The role of UPS is crucial in regulating protein levels through degradation to maintain fundamental cellular processes such as growth, division, signal transduction, and stress response. Dysregulation of the UPS, resulting in loss of ability to maintain protein quality through proteolysis, is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss functional links of dysregulated UPS in human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing clinical trials, are also presented in this review.

E3 Ubiquitin Ligase UBR5 Promotes the Metastasis of Pancreatic Cancer via Destabilizing F-Actin Capping Protein CAPZA1

The ubiquitin-proteasome system (UPS) is a regulated mechanism of intracellular protein degradation and turnover, and its dysfunction is associated with various diseases including cancer. UBR5, an E3 ubiquitin ligase, is emerging as an important regulator of the UPS in cancers, but its role in pancreatic cancer is poorly understood. Here, we show that UBR5 is significantly upregulated in pancreatic cancer tissues. High UBR5 expression is correlated with increased lymph node metastasis and poor survival of patients. The loss-of-function and gain-of-function studies demonstrated that UBR5 substantially enhanced the in vitro migratory and invasive ability of pancreatic cancer cells. UBR5 knockdown also markedly inhibited in vivo cancer metastasis in the liver metastatic model of pancreatic cancer in nude mice, suggesting UBR5 as a potent metastatic promoter in pancreatic cancer. Furthermore, using co-immunoprecipitation combined with mass spectrometry analyses, CAPZA1, a member of F-actin capping protein α subunit family, was identified as a novel substrate of UBR5. UBR5 overexpression could promote the degradation of CAPZA1 via the UPS and induce the accumulation of F-actin, which has been described as an essential molecular event during the process of CAPZA1 deficiency-induced cancer cells migration and invasion. UBR5 knockdown significantly increased the intracellular level of CAPZA1 and CAPZA1 downregulation largely reversed the UBR5 knockdown-induced suppression of cell migration and invasion in pancreatic cancer cells. Collectively, our findings unveil UBR5 as a novel and critical regulator of pancreatic cancer metastasis and highlight the potential for UBR5-CAPZA1 axis as a therapeutic target for preventing metastasis in pancreatic cancer patients, especially in those with increased UBR5 expression.

Identification of potential target genes and crucial pathways in small cell lung cancer based on bioinformatic strategy and human samples

Small cell lung cancer (SCLC) is a carcinoma of the lungs with strong invasion, poor prognosis and resistant to multiple chemotherapeutic drugs. It has posed severe challenges for the effective treatment of lung cancer. Therefore, searching for genes related to the development and prognosis of SCLC and uncovering their underlying molecular mechanisms are urgent problems to be resolved. This study is aimed at exploring the potential pathogenic and prognostic crucial genes and key pathways of SCLC via bioinformatic analysis of public datasets. Firstly, 117 SCLC samples and 51 normal lung samples were collected and analyzed from three gene expression datasets. Then, 102 up-regulated and 106 down-regulated differentially expressed genes (DEGs) were observed. And then, functional annotation and pathway enrichment analyzes of DEGs was performed utilizing the FunRich. The protein-protein interaction (PPI) network of the DEGs was constructed through the STRING website, visualized by Cytoscape. Finally, the expression levels of eight hub genes were confirmed in Oncomine database and human samples from SCLC patients. It showed that CDC20, BUB1, TOP2A, RRM2, CCNA2, UBE2C, MAD2L1, and BUB1B were upregulated in SCLC tissues compared to paired adjacent non-cancerous tissues. These suggested that eight hub genes might be viewed as new biomarkers for prognosis of SCLC or to guide individualized medication for the therapy of SCLC.

Single-cell transcriptional profiling identifies a cluster of potential metastasis-associated UBE2C+ cells in immature ovarian teratoma

To dissect the disease heterogeneity and identify the underlying cellular and molecular events related to metastasis of immature ovarian teratoma in children, single-cell RNA sequencing was performed for a 2-year-old patient with liver metastases from immature ovarian teratoma. A total of 5976 cells were obtained for further analysis, with a median unique molecular identifier count of 6011 per cell and a median number of 1741 genes detected per cell. Fourteen clusters were recognized, with the main lineages comprising epithelial cells, macrophages, fibroblasts, glial cells, and dendritic cells. Ten subclusters of epithelial cells were further defined, originating from the urinary tract, esophagus, bronchus, lung, skin, and gastrointestinal tract. An undefined UBE2C + population in an active state of proliferation was also identified and its biological processes were related to meiosis and maturation of oocytes. Pseudotime analysis revealed different distributions of epithelial cells in the development trajectory. In conclusion, a cluster of UBE2C + epithelial cells in an active state of proliferation was identified in an immature ovarian teratoma in a child, and may contribute to metastasis by regulating epithelial-mesenchymal transition. These findings help toward understanding the origin of the malignant behaviors, offer a potential biomarker for early determination of the tumor nature, and provide new ideas for the therapy of immature ovarian teratoma in children.

UBE2C Overexpression Aggravates Patient Outcome by Promoting Estrogen-Dependent/Independent Cell Proliferation in Early Hormone Receptor-Positive and HER2-Negative Breast Cancer

We previously showed that UBE2C mRNA expression is significantly associated with poor prognosis only in patients with hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)– breast cancer. In this study, we further reanalyzed the correlation between UBE2C mRNA expression and clinical outcomes in patients with HR+/HER2– breast cancer, and we investigated the molecular mechanism underlying the role of UBE2C modulation in disease progression in this subgroup of patients. Univariate and multivariate analyses showed that high UBE2C expression was associated with significantly shorter survival of breast cancer patients with pN0 and pN1 tumors but not pN2/N3 tumors (P < 0.05). In vitro functional experiments in HR+/HER2– breast cancer cells showed that UBE2C expression is a tumorigenic factor, and that estrogen upregulated UBE2C mRNA and protein by directly binding to the UBE2C promoter region. UBE2C knockdown inhibited cell proliferation by affecting cell cycle progression, and UBE2C overexpression was associated with estrogen-independent growth. UBE2C depletion markedly increased the cytotoxicity of tamoxifen by inducing apoptosis. The present findings suggest that UBE2C overexpression is correlated with relapse and promotes estrogen-dependent/independent proliferation in early HR+/HER2– breast cancer.

Ubiquitin-Regulated Cell Proliferation and Cancer

Ubiquitin ligases (E3) play a crucial role in the regulation of different cellular processes such as proliferation and differentiation via recognition, interaction, and ubiquitination of key cellular proteins in a spatial and temporal regulated manner. The type of ubiquitin chain formed determines the fate of the substrates. The ubiquitinated substrates can be degraded by the proteasome, display altered subcellular localization, or can suffer modifications on their interaction with functional protein complexes. Deregulation of E3 activities is frequently found in various human pathologies, including cancer. The illegitimated or accelerated degradation of oncosuppressive proteins or, inversely, the abnormally high accumulation of oncoproteins, contributes to cell proliferation and transformation. Anomalies in protein abundance may be related to mutations that alter the direct or indirect recognition of proteins by the E3 enzymes or alterations in the level of expression or activity of ubiquitin ligases. Through a few examples, we illustrate here the complexity and diversity of the molecular mechanisms related to protein ubiquitination involved in cell cycle regulation. We will discuss the role of ubiquitin-dependent degradation mediated by the proteasome, the role of non-proteolytic ubiquitination during cell cycle progression, and the consequences of this deregulation on cellular transformation. Finally, we will highlight the novel opportunities that arise from these studies for therapeutic intervention.

Silencing ubiquitin-conjugating enzyme 2C inhibits proliferation and epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma

Ubiquitin-conjugating enzyme 2C (UBE2C) is a core ubiquitin-conjugating enzyme in the ubiquitin-proteasome system that promotes cell cycle progression. Previous studies have indicated that UBE2C mediates tumorigenesis and progression in various cancers, but its role in pancreatic ductal adenocarcinoma (PDAC) remains unclear. This study elucidated the function of UBE2C in PDAC tumorigenesis and progression by determining UBE2C expression via real-time qPCR, western blotting and immunohistochemistry. The associations between UBE2C expression and clinicopathological characteristics and survival were assessed using a tissue microarray based on a multicentre PDAC cohort. We found that UBE2C was strongly expressed in PDAC patient tissues and was negatively associated with clinical stage, lymph node metastasis, perineural invasion and survival (all P < 0.05). Multivariate analysis revealed that high UBE2C expression is an independent risk factor for PDAC (P = 0.001). In the PDAC cell lines CFPAC-1 and Panc-1, silencing UBE2C suppressed cell proliferation by inducing G1/S arrest mediated by downregulation of cyclin D1. Furthermore, UBE2C knockdown decreased the migration of PDAC cells in vitro by downregulating epithelial-mesenchymal transition (EMT). RNA-seq analysis showed that upon silencing UBE2C in CFPAC-1 cells, cyclin D1 and vimentin were downregulated by approximately 3.5-fold and 2.6-fold, respectively, and the major enriched pathways were related to cell cycle progression. Experiments on tumour-bearing mice injected with CFPAC-1 cells indicated that UBE2C depletion significantly inhibits tumour growth in vivo. These results suggest that UBE2C is involved in the development and progression of PDAC by regulating cell proliferation and EMT. UBE2C is a novel potential therapeutic target for pancreatic cancer. DATABASE: Data are available in the GEO database under accession number GSE137172.

A Comprehensive Bioinformatics Analysis of UBE2C in Cancers

Ubiquitination is one of the main post-translational modification of proteins. It plays key roles in a broad range of cellular functions, including protein degradation, protein interactions, and subcellular location. In the ubiquitination system, different proteins are involved and their dysregulation can lead to various human diseases, including cancers. By using data available from the Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases, we here show that the ubiquitin conjugating enzyme, E2C (UBE2C), is overexpressed in all 27 cancers we investigated. UBE2C expression is significantly higher in late-stage tumors, which might indicate its involvement in tumor progression and invasion. This study also revealed that patients with higher UBE2C levels showed a shorter overall survival (OS) time and worse OS prognosis. Moreover, our data show that UBE2C higher-expression leads to worse disease-free survival prognosis (DFS), indicating that UBE2C overexpression correlates with poor clinical outcomes. We also identified genes with positive correlations with UBE2C in several cancers. We found a number of poorly studied genes (family with sequence similarity 72-member D, FAM72D; meiotic nuclear divisions 1, MND1; mitochondrial fission regulator 2, MTFR2; and POC1 centriolar protein A, POC1A) whose expression correlates with UBE2C. These genes might be considered as new targets for cancers therapies since they showed overexpression in several cancers and correlate with worse OS prognosis.

Identification of Candidate Biomarkers Correlated With the Pathogenesis and Prognosis of Non-small Cell Lung Cancer via Integrated Bioinformatics Analysis

Background and Objective: Non-small cell lung cancer (NSCLC) accounts for 80-85% of all patients with lung cancer and 5-year relative overall survival (OS) rate is less than 20%, so that identifying novel diagnostic and prognostic biomarkers is urgently demanded. The present study attempted to identify potential key genes associated with the pathogenesis and prognosis of NSCLC. Methods: Four GEO datasets (GSE18842, GSE19804, GSE43458, and GSE62113) were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between NSCLC samples and normal ones were analyzed using limma package, and RobustRankAggreg (RRA) package was used to conduct gene integration. Moreover, Search Tool for the Retrieval of Interacting Genes database (STRING), Cytoscape, and Molecular Complex Detection (MCODE) were utilized to establish protein-protein interaction (PPI) network of these DEGs. Furthermore, functional enrichment and pathway enrichment analyses for DEGs were performed by Funrich and OmicShare. While the expressions and prognostic values of top genes were carried out through Gene Expression Profiling Interactive Analysis (GEPIA) and Kaplan Meier-plotter (KM) online dataset. Results: A total of 249 DEGs (113 upregulated and 136 downregulated) were identified after gene integration. Moreover, the PPI network was established with 166 nodes and 1784 protein pairs. Topoisomerase II alpha (TOP2A), a top gene and hub node with higher node degrees in module 1, was significantly enriched in mitotic cell cycle pathway. In addition, Interleukin-6 (IL-6) was enriched in amb2 integrin signaling pathway. The mitotic cell cycle was the most significant pathway in module 1 with the highest P-value. Besides, five hub genes with high degree of connectivity were selected, including TOP2A, CCNB1, CCNA2, UBE2C, and KIF20A, and they were all correlated with worse OS in NSCLC. Conclusion: The results showed that TOP2A, CCNB1, CCNA2, UBE2C, KIF20A, and IL-6 may be potential key genes, while the mitotic cell cycle pathway may be a potential pathway contribute to progression in NSCLC. Further, it could be used as a new biomarker for diagnosis and to direct the synthesis medicine of NSCLC.

Concise machinery for monitoring ubiquitination activities using novel artificial RING fingers

Protein ubiquitination is involved in many cellular processes, such as protein degradation, DNA repair, and signal transduction pathways. Ubiquitin-conjugating (E2) enzymes of the ubiquitination pathway are associated with various cancers, such as leukemia, lung cancer, and gastric cancer. However, to date, detection of E2 activities is not practicable for capturing the pathological conditions of cancers due to complications related to the enzymatic cascade reaction. To overcome this hurdle, we have recently investigated a novel strategy for measuring E2 activities. Artificial RING fingers (ARFs) were developed to conveniently detect E2 activities during the ubiquitination reaction. ARFs were created by grafting the active sites of ubiquitin-ligating (E3) enzymes onto amino acid sequences with 38 residues. The grafting design downsized E3s to small molecules (ARFs). Such an ARF is a multifunctional molecule that possesses specific E2-binding capabilities and ubiquitinates itself without a substrate. In this review, we discuss the major findings from recent investigations on a new molecular design for ARFs and their simplified detection system for E2 activities. The use of the ARF allowed us to monitor E2 activities using acute promyelocytic leukemia (APL)-derived cells following treatment with the anticancer drug bortezomib. The molecular design of ARFs is extremely simple and convenient, and thus, may be a powerful tool for protein engineering. The ARF methodology may reveal a new screening method of E2s that will contribute to diagnostic techniques for cancers.

Personalized Proteome Profiles of Healthy and Tumor Human Colon Organoids Reveal Both Individual Diversity and Basic Features of Colorectal Cancer

Diseases at the molecular level are complex and patient dependent, necessitating development of strategies that enable precision treatment to optimize clinical outcomes. Organoid technology has recently been shown to have the potential to recapitulate the in vivo characteristics of the original individual's tissue in a three-dimensional in vitro culture system. Here, we present a quantitative mass-spectrometry-based proteomic analysis and a comparative transcriptomic analysis of human colorectal tumor and healthy organoids derived, in parallel, from seven patients. Although gene and protein signatures can be derived to distinguish the tumor organoid population from healthy organoids, our data clearly reveal that each patient possesses a distinct organoid signature at the proteomic level. We demonstrate that a personalized patient-specific organoid proteome profile can be related to the diagnosis of a patient and with future development contribute to the generation of personalized therapies.

The clinicopathological significance of UBE2C in breast cancer: a study based on immunohistochemistry, microarray and RNA-sequencing data

BACKGROUND

Ubiquitin-conjugating enzyme E2C (UBE2C) has been previously reported to correlate with the malignant progression of various human cancers, however, the exact molecular function of UBE2C in breast carcinoma (BRCA) remained elusive. We aimed to investigate UBE2C expression in BRCA and its clinical significance.

METHODS

The expression of UBE2C in 209 BRCA tissue samples and 53 adjacent normal tissue samples was detected using immunohistochemistry. The clinical role of UBE2C was analyzed. Public databases including the human protein atlas and Oncomine were used to assess UBE2C expression in BRCA. Moreover, the cancer genome atlas (TCGA) database was employed to investigate the prognostic value of UBE2C in BRCA.

RESULTS

The positive expression rate of UBE2C in BRCA was 70.8% (148/209), and UBE2C expression in the adjacent breast tissue was negative. The expression of UBE2C was positively correlated with tumor size (r = 0.32, P < 0.001), histological grade (r = 0.237, P = 0.001), clinical stage (r = 0.198, P = 0.004), lymph node metastasis (r = 0.155, P = 0.026), HER2 expression level (r = 0.356, P < 0.001), Ki-67 expression level (r = 0.504, P < 0.001), and P53 expression level (r = 0.32, P = 0.001). Negative correlations were found between UBE2C expression and the ER (r = - 0.403, P < 0.001) and PR (r = - 0.468, P < 0.001) status. UBE2C gene expression data from the public databases all proved that UBE2C was overexpressed in BRCA. According to the TCGA data analysis, a higher positive expression of UBE2C was associated with worse survival of BRCA patients (P = 0.0428), and data from cBioPortal indicated that 11% of all sequenced BRCA patients possessed a gene alteration of UBE2C, predominately gene amplification and mRNA regulation.

CONCLUSION

Ubiquitin-conjugating enzyme E2C might pose an oncogenic effect on the progression of BRCA.

UBE2C induces EMT through Wnt/β‑catenin and PI3K/Akt signaling pathways by regulating phosphorylation levels of Aurora-A

The ubiquitin-conjugating enzyme 2C (UBE2C) is the key component in the ubiquitin proteasome system (UPS) by partnering with the anaphase‑promoting complex (APC/C). A high UBE2C protein expression level has been reported in various types of human tumors. However, little is known about the precise mechanism by which UBE2C expression is downregulated in gastric cancer. We found in MGC‑803 and SGC‑7901 gastric cancer cells UBE2C‑deficient G2/M phase arrest in the cell cycle and subsequently decreased gastric adenocarcinoma tumorigenesis. In the previous study, we identified Aurora-A (AURKA) as the hub gene of the gastric cancer linkage network based genome‑wide association study (eGWAS). Furthermore, knockdown of UBE2C using siRNA markedly reduced the level of phosphorylation AURKA (p‑AURKA) via Wnt/β‑catenin and PI3K/Akt signaling pathways suppressed the occurrence and development of gastric cancer. Additionally, the expression of E‑cadherin was up‑regulated and N-cadherin was downregulated in response to UBE2C knockdown and inhibits epithelial-mesenchymal transition (EMT). Collectively, our data suggest that the activity of AURKA might be regulated by UBE2C through regulating the activity of APC/C. UBE2C may be a new marker in the diagnosis of gastric cancer and may be a potential therapeutic target for the treatment of gastric adenocarcinoma.

Induction of cell proliferation, clonogenicity and cell accumulation in S phase as a consequence of human UBE2Q1 overexpression

Ubiquitination is an important cellular mechanism with a pivotal role in the degradation of abnormal or short-lived proteins and the regulation of cell cycle and cell growth. The ubiquitin-proteasome pathway is altered in multiple types of human malignancies, including colorectal cancer (CRC). The alteration in the expression of the novel human gene ubiquitin-conjugating enzyme E2 Q1 (UBE2Q1), as a putative member of the E2 ubiquitin-conjugating enzyme family, has been reported in several malignancies, including carcinoma of the breast, hepatocellular and colorectal cancer, and pediatric acute lymphoblastic leukemia. In the present study, the effect of UBE2Q1 overexpression on cell growth, clonogenicity, motility and cell cycle was investigated in a CRC cell line. The UBE2Q1 gene was cloned in the pCMV6-AN-GFP expression vector. A series of stable transfectants of SW1116 cells overexpressing UBE2Q1 protein were established and confirmed by fluorescence microscopy and western blotting. Using these cells, MTT assay was performed to evaluate cell growth and proliferation, while crystal violet staining was used for clonogenicity assay. Cell cycle analysis was also performed to survey the ratio of cells accumulated in different phases of the cell cycle upon transfection. The motility of these cells was also studied using wound healing assay. UBE2Q1 transfectants exhibited a faster growth in cell culture, increased colony formation capacity and enhanced motility compared with control non-transfected cells and cells transfected with empty vector (mock-transfected cells). UBE2Q1 overexpression also resulted in a significant decrease in the number of cells accumulated in the G0/G1 phase of the cell cycle. The present findings suggest that UBE2Q1 may function as an oncogene that induces proliferation of cancer cells, and could be a novel diagnostic tool and a potential therapeutic target for CRC.

Ubiquitin-conjugating enzyme UbcH10 promotes gastric cancer growth and is a potential biomarker for gastric cancer

Gastric cancer is a fatal disease and the availability of early diagnostic methods is limited. There is an urgent need to identify effective targets for early diagnosis and therapeutics. UbcH10 is a ubiquitin-conjugating enzyme with high expression in various types of cancers. In the present study, several gastric tumor cell lines with high or low expression of UbcH10 were exploited to study the role of UbcH10 in gastric cancer. Knockdown of UbcH10 expression using siRNA in gastric cancer cell lines with high expression of UbcH10 resulted in reduced proliferation, increased cisplatin-induced apoptosis and reduced serum-induced ERK, Akt and p38 phosphorylation signaling. In agreement, overexpression of UbcH10 in gastric cancer cell lines with low expression of UbcH10 led to enhanced cell proliferation and resistance to cisplatin-induced apoptosis. Most importantly, IHC analyses showed that the UbcH10 protein was expressed at a high level in most patient gastric cancer tissues, but was absent in adjacent mesenchyme tissues. These data suggest that UbcH10 may promote gastric cancer growth and can serve as a biomarker for diagnosis or as a target for novel therapeutics in gastric cancer.

UbcH10 expression can predict prognosis and sensitivity to the antineoplastic treatment for colorectal cancer patients

Colorectal cancer (CRC) is one of the most frequent and deadly malignancies worldwide. Despite the progresses made in diagnosis and treatment, the identification of tumor markers is still a strong clinical need, because current treatments are efficacious only in a subgroup of patients. UbcH10 represents a potential candidate biomarker, whose expression levels could be employed to predict response or resistance to chemotherapy or targeted agents. UbcH10 mRNA and protein expression levels have been evaluated in a large group of CRC patients and correlated with clinico-pathological characteristics, including KRAS mutations. Moreover, the endogenous levels of UbcH10 and its role on cell growth have been evaluated in CRC cells. Finally, to investigate the impact of UbcH10 protein expression on the response to irinotecan, its active metabolite SN-38 and cetuximab treatment, UbcH10 silencing experiments were carried-out on two colon carcinoma cell lines, Caco-2, and DLD1. Overexpression of UbcH10 mRNA and protein was observed in the vast majority of patients analyzed. UbcH10 suppression decreased CRC cell growth rate (at least in part through deregulation of Cyclin B and ERK1) and sensitized them to pharmacological treatments with irinotecan, SN-38 and cetuximab (at least in part through a down-regulation of AKT). Taken together, these findings indicate that UbcH10 expression regulates CRC growth and could play an important role in the personalization of the therapy of CRC patients.

Ubiquitin-conjugating enzyme E2C regulates apoptosis-dependent tumor progression of non-small cell lung cancer via ERK pathway

The oncogenic role of ubiquitin-conjugating enzyme E2C (UBE2C) had been identified in some types of human tumors, while the clinical and biological role of UBE2C in non-small cell lung cancer (NSCLC) is still elusive. Here, we have determined the specific role of UBE2C in NSCLC. Western blot and qRT-PCR were used for detecting the mRNA level and protein level of UBE2C in NSCLC samples and cell lines, respectively. Lentivirus product was used to conduct loss of function assay. qRT-PCR array was employed to detect potential downstream genes regulated by UBE2C. As the result, UBE2C mRNA level was approximately threefold overexpression in NSCLC tissues compared with normal tissues, while a sharp change was detected at protein level. Overexpression of UBE2C in lung cancer samples was correlated with advanced pathological stage. UBE2C regulated cell growth in an apoptosis-dependent way. PCR Array analysis revealed that UBE2C regulated the expression of genes associated with tumor growth, apoptosis, and angiogenesis. Furthermore, UBE2C could regulate phospho-ERK1/2 level but not STAT3, YAP, or AKT pathway, which was accompanied with the classic function of ERK pathway in cell growth and apoptosis. In conclusion, our results indicated UBE2C might be a novel therapeutic target in NSCLC.

Effects of ubiquitin-conjugating enzyme 2C on invasion, proliferation and cell cycling of lung cancer cells

The aims of this study were to investigate the influence of ubiquitin- conjugating enzyme E2C (UBE2C) on biological behavior of lung cancer cells. Using MTT, flow cytometry and invasion assays, we detected UBE2C expression and evaluated its biological properties in these cells, including effects on proliferation, the cell cycle profile and invasive capability. Compared with control cells, the UBE2C transfected cells demonstrated increased cellular proliferation (p<0.05). UBE2C transfected cells also had a lower percentage in G1 phase and a higher percentage in S phase (p<0.05). Importantly, the UBE2C transfected cells had a notable enhancement of cell numbers penetrating the basement membrane compared with the control group (p<0.05). Ectopic up- regulation UBE2C promoted the growth of lung cancer cells in vivo. Furthermore, we found UBE2C increased the expression of cyclin D1 and MMP-2. These results show UBE2C may represent a potential therapeutic target for lung cancer.

UbcH10 overexpression increases carcinogenesis and blocks ALLN susceptibility in colorectal cancer

Cyclins are essential for cell proliferation, the cell cycle and tumorigenesis in all eukaryotes. UbcH10 regulates the degradation of cyclins in a ubiquitin-dependent manner. Here, we report that UbcH10 is likely involved in tumorigenesis. We found that cancer cells exposed to n-acetyl-leu-leu-norleucinal (ALLN) treatment and UbcH10 depletion exhibit a synergistic therapeutic effect. Abundant expression of UbcH10 drives resistance to ALLN-induced cell death, while cells deficient in UbcH10 were susceptible to ALLN-induced cell death. The depletion of UbcH10 hindered tumorigenesis both in vitro and in vivo, as assessed by colony formation, growth curve, soft agar and xenograft assays. These phenotypes were efficiently rescued through the introduction of recombinant UbcH10. In the UbcH10-deficient cells, alterations in the expression of cyclins led to cell cycle changes and subsequently decreases in tumorigenesis. The tumorigenesis of xenograft tumors from UbcH10-deficient cells treated with ALLN was decreased relative to wild-type cells treated with ALLN in nude mice. On the molecular level, we observed that UbcH10 deficiency enhances the activation of caspase 8 and caspase 3 but not caspase 9 to impair cell viability upon ALLN treatment. Collectively, our results suggest that, as an oncogene, UbcH10 is a potential drug target for the treatment of colorectal cancer.

Involvement of ubiquitin-conjugating enzyme E2C in proliferation and invasion of prostate carcinoma cells

Ubiquitin-conjugating enzyme E2C (UBE2C) has been found to participate in the process of several cancers. However, the role of UBE2C in prostate cancer has not been reported. To investigate the function of UBE2C in prostate cancer, several methods were used. UBE2C promoted the proliferation and viability of prostate cancer cells through MTT and colony formation assay and increased the number of invaded or migrated cells in Matrigel or Transwell assay based on its function of inducing EMT. UBE2C also promoted tumor formation in vivo. Our results suggest that UBE2C acts as an oncogene in prostate cancer progression and may be a candidate marker of diagnosis for this disease.

Inhibition of ubiquitin conjugating enzyme UBE2C reduces proliferation and sensitizes breast cancer cells to radiation, doxorubicin, tamoxifen and letrozole

PURPOSE

The objective of this study was to determine radiation, doxorubicin, tamoxifen and letrozole sensitivity of breast cancer cells in response to functional inhibition of the ubiquitin conjugating enzyme UBE2C.

METHODS

Taqman Real time PCR was performed to measure UBE2C levels in breast cancer cell lines and control HBL100 and HEK293T cells. A dominant negative form of UBE2C (DN-UBE2C) was used to functionally inhibit wild type UBE2C. Cell proliferation and anchorage independent growth were measured by colorimetric and soft agar assays, respectively. Radiation, doxorubicin, tamoxifen and letrozole responses of the cell lines were assessed by colorimetric and clonogenic assays.

RESULTS

Overexpression of UBE2C was observed in all breast cancer cell lines tested using quantitative real time PCR. UBE2C expression was found to be highest in MDAMB231 and relatively lowest in MCF7 cells, compared to control cells. Both the growth rate and the anchorage independent growth of MCF7 and MDAMB231 cells transfected with DN-UBE2C were significantly reduced compared to cells transfected with vector alone. MCF7 and MDAMB231 cells expressing DN-UBE2C were significantly more sensitive to different doses of radiation and doxorubicin compared to both wild type and vector alone transfected cells. In addition, DN-UBE2C transfected MCF7 cells were more sensitive to inhibition by tamoxifen and letrozole compared to wild type and vector alone transfected cells.

CONCLUSIONS

Our results show that inhibition of UBE2C sensitizes breast cancer cells to radiation, doxorubicin and hormone blocking agents. UBE2C may, therefore, serve as a potential therapeutic target aimed at inducing radiation and chemo sensitization.

High expression of ubiquitin-conjugating enzyme 2C (UBE2C) correlates with nasopharyngeal carcinoma progression

Background

Overexpression of ubiquitin-conjugating enzyme 2C (UBE2C) has been detected in many types of human cancers, and is correlated with tumor malignancy. However, the role of UBE2C in human nasopharyngeal carcinoma (NPC) is unclear. In this study, we investigated the role of aberrant UBE2C expression in the progression of human NPC.

Methods

Immunohistochemical analysis was performed to detect UBE2C protein in clinical samples of NPC and benign nasopharyngeal tissues, and the association of UBE2C expression with patient clinicopathological characteristics was analyzed. UBEC2 expression profiles were evaluated in cell lines representing varying differentiated stages of NPC and immortalized nasopharyngeal epithelia NP-69 cells using quantitative RT-PCR, western blotting and fluorescent staining. Furthermore, UBE2C was knocked down using RNA interference in these cell lines and proliferation and cell cycle distribution was investigated.

Results

Immunohistochemical analysis revealed that UBE2C protein expression levels were higher in NPC tissues than in benign nasopharyngeal tissues (P<0.001). Moreover, high UBE2C protein expression was positively correlated with tumor size (P=0.017), lymph node metastasis (P=0.016) and distant metastasis (P=0.015) in NPC patients. In vitro experiments demonstrated that UBE2C expression levels were inversely correlated with the degree of differentiation of NPC cell lines, whereas UBE2C displayed low level of expression in NP-69 cells. Knockdown of UBE2C led to significant arrest at the S and G2/M phases of the cell cycle, and decreased cell proliferation was observed in poorly-differentiated CNE2Z NPC cells and undifferentiated C666-1 cells, but not in well-differentiated CNE1 and immortalized NP-69 cells.

Conclusions

Our findings suggest that high expression of UBE2C in human NPC is closely related to tumor malignancy, and may be a potential marker for NPC progression.

A monoclonal antibody against a potential cancer biomarker, human ubiquitin-conjugating enzyme E2

Human ubiquitin-conjugating enzyme E2, also known as UbcH10, is defined as a cyclin-selective ubiquitin carrier protein and is essential for selective degradation of many short-lived proteins in eukaryotic cells. Recently more and more data show that UbcH10 could be a potential cancer biomarker. In this study, we have developed a monoclonal antibody (MAb) against UbcH10 using an expression recombinant protein. Hybridomas F001, F007, and F008 with high affinities belong to IgG1 subclass with κ light and are highly specific for UbcH10. Further experimentation showed that MAbs F001, F007, and F008 are suitable for the development of immunoassay core agents with sufficient sensitivity and specificity in vitro by Western-blot, immunofluorescence, and immunohistochemistry. These MAbs can be used as a tool for further investigation on functions related to the role of UbcH10 in tumorigenesis and development.

UbcH10 Expression in Benign, Hyperplastic, and Malignant Endometrial Curetted Materials

The aim of this study was to investigate the role of UbcH10 expression in the differential diagnosis of benign, hyperplastic, and malignant endometrial tissues and also the relationship of UbcH10 with the clinicopathologic parameters of malignant cases. A tissue microarray was performed for 81 endometrial curettage biopsies, which histological diagnosis had demonstrated to be 13 cases of proliferative endometrium, 7 cases of disordered proliferative endometrium, 5 cases of complex atypical hyperplasia, 24 cases of nonatypical hyperplasia, and 32 cases of endometrioid adenocarcinoma. Expression of UbcH10 was assessed by immunohistochemistry. When groups were compared according to UbcH10 percentages and scores, a statistically significant difference was found only between the carcinoma group and the other groups, except the complex atypical hyperplasia group ( P < .05). In the malignant group, UbcH10 percentages and scores were only significantly related to age. There was no significant association between UbcH10 expression and tumor grade and stage. Overexpression of UbcH10 may be a useful indicator of endometrial carcinoma. UbcH10 also deserves further evaluation in the detection of prognostic mean and also for its role in endometrial carcinogenesis.

Dominant negative Ubiquitin-conjugating enzyme E2C sensitizes cervical cancer cells to radiation

PURPOSE

To find the radiation sensitivity of human cervical carcinoma cell lines and to investigate the effect of the dominant negative-Ubiquitin-conjugating enzyme E2C (DN-UBE2C) on cell proliferation and radiation response.

MATERIALS AND METHODS

Radiation sensitivities of human cervical cell lines (SiHa, HeLa, BU25TK, ME 180, and C33A) were analyzed by assessing their cell survival after irradiation by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Soft agar cloning assay, growth curve and radiation response of DN-UBE2C stably transfected SiHa and HeLa cell lines were assessed by MTS assay and Clonogenic assay.

RESULTS

Difference in sensitivity to radiation was observed among the cervical cancer cell lines studied. SiHa was found to be the most resistant cell line whereas C33A cells were the most sensitive. The growth rate of SiHa and HeLa transfected with DN-UBE2C was significantly reduced compared to vector control. Furthermore, DN-UBE2C-mediated radiosensitivity was correlated with a significant decrease in resistance to radiation by SiHa and HeLa cells after transfection with the DN-UBE2C when compared to control cultures.

CONCLUSION

These results suggested that the Ubiquitin-conjugating enzyme E2C (UBE2C) gene is a potential therapeutic target for cervical cancer treatment.

Curcumin potentiates antitumor activity of L-asparaginase via inhibition of the AKT signaling pathway in acute lymphoblastic leukemia

L-asparaginase (L-ASP) is a universal component of therapy for acute lymphoblastic leukemia (ALL). Curcumin is a naturally occurring yellow pigment that is derived from the rhizome of Curcuma longa. In this study, we evaluated the cytotoxicity of the combined treatment of L-ASP and curcumin in three ALL cell lines. Synergistic cytotoxicity was observed in all three cell lines following the combined treatment of curcumin and L-ASP. Our results revealed that curcumin significantly enhanced the antitumor effect of L-ASP in the three ALL cell lines compared to that for L-ASP alone ( p < 0.05). Curcumin and L-ASP co-treatments induced apoptosis, via activation and cleavage of caspase-8 and BID cleavage accompanied by release of cytochrome c and activation of caspase-9/3, compared to the group treated with only L-ASP and the control group. Furthermore, the combination of curcumin and L-ASP led to significant reductions in phosphorylated AKT and expression of AKT-regulated gene products (FoxO1, GSK3β, IKKα, NF-κB, XIAP) compared with the group treated with only L-ASP and the control group. Overall, our findings suggest that curcumin potentiates the antitumor effects of L-ASP in acute lymphoblastic leukemia by constitutively inhibiting AKT and AKT-regulated gene products.

Ubiquitin-conjugating enzyme UBE2C: molecular biology, role in tumorigenesis, and potential as a biomarker

Ubiquitin-conjugating enzyme 2C (UBE2C) participates in cell cycle progression and checkpoint control by targeted degradation of short-lived proteins. As a conjugating enzyme, it directs polyubiquitination to preferred lysine in the substrates. In addition to its well-known role in cyclin B destruction that is essential for exit from mitosis, UBE2C also plays an important role in mitotic spindle checkpoint control. Cells overexpressing UBE2C ignore the mitotic spindle checkpoint signals and lose genomic stability, which is a hallmark of cancer. UBE2C expression is upregulated upon malignant transformation, and amplification of UBE2C is often seen at the chromosome level in cancers in a manner similar to c-Myc, which is directly upstream of UBE2C. UBE2C levels are upregulated in a wide range of solid tumors and hematological malignancies. The level of expression correlates with the aggressiveness of the tumor. High UBE2C expression is predictive of poor survival and perhaps high risk for relapse. UBE2C immunochemistry may be integrated into the diagnosis of thyroid malignancy and gliomas. This minireview summarizes what is known about the function of UBE2C focusing on its role in the regulation of spindle assembly checkpoint, its part in tumorigenesis, and its potential as a tumor marker for various cancers.

CCI-779 inhibits cell-cycle G2-M progression and invasion of castration-resistant prostate cancer via attenuation of UBE2C transcription and mRNA stability

The cell-cycle G(2)-M phase gene UBE2C is overexpressed in various solid tumors including castration-resistant prostate cancer (CRPC). Our recent studies found UBE2C to be a CRPC-specific androgen receptor (AR) target gene that is necessary for CRPC growth, providing a potential novel target for therapeutic intervention. In this study, we showed that the G(1)-S cell-cycle inhibitor-779 (CCI-779), an mTOR inhibitor, inhibited UBE2C mRNA and protein expression in AR-positive CRPC cell models abl and C4-2B. Treatment with CCI-779 significantly decreased abl cell proliferation in vitro and in vivo through inhibition of cell-cycle progression of both G(2)-M and G(1)-S phases. In addition, exposure of abl and C4-2B cells to CCI-779 also decreased UBE2C-dependent cell invasion. The molecular mechanisms for CCI-779 inhibition of UBE2C gene expression involved a decreased binding of AR coactivators SRC1, SRC3, p300, and MED1 to the UBE2C enhancers, leading to a reduction in RNA polymerase II loading to the UBE2C promoter, and attenuation of UBE2C mRNA stability. Our data suggest that, in addition to its ability to block cell-cycle G(1) to S-phase transition, CCI-779 causes a cell-cycle G(2)-M accumulation and an inhibition of cell invasion through a novel UBE2C-dependent mechanism, which contributes to antitumor activities of CCI-779 in UBE2C overexpressed AR-positive CRPC.

Emerging roles for Lys11-linked polyubiquitin in cellular regulation

Polyubiquitin chains are assembled via one of seven lysine (Lys) residues or the N terminus. The cellular roles of Lys48- and Lys63-linked polyubiquitin have been extensively studied; however, the cellular functions of Lys11-linked chains are less well understood. Recent insights into Lys11-linked ubiquitin chains have revealed their important function in cell cycle control. Additionally, Lys11 linkages have been identified in the context of mixed chains in many other cellular pathways. In this review, we introduce the specific enzymes that mediate Lys11-linked chain assembly and disassembly, and discuss the diverse cellular processes in which Lys11 linkages participate. Notably, mechanistic insights have revealed how the E2 ubiquitin-conjugating enzyme UBE2S achieves its Lys11 linkage specificity, and two structures of Lys11-linked polyubiquitin highlight the dynamic nature of this compact chain type.

Ubiquitin-like protein conjugation and the ubiquitin-proteasome system as drug targets

The ubiquitin-proteasome system (UPS) and ubiquitin-like protein (UBL) conjugation pathways are integral to cellular protein homeostasis. The growing recognition of the fundamental importance of these pathways to normal cell function and in disease has prompted an in-depth search for small-molecule inhibitors that selectively block the function of these pathways. However, our limited understanding of the molecular mechanisms and biological consequences of UBL conjugation is a significant hurdle to identifying drug-like inhibitors of enzyme targets within these pathways. Here, we highlight recent advances in understanding the role of some of these enzymes and how these new insights may be the key to developing novel therapeutics for diseases including immuno-inflammatory disorders, cancer, infectious diseases, cardiovascular disease and neurodegenerative disorders.