UBE2D3 is a positive prognostic factor and is negatively correlated with hTERT expression in esophageal cancer

Isoform alterations in the ubiquitination machinery impacting gastrointestinal malignancies

The advancement of RNAseq and isoform-specific expression platforms has led to the understanding that isoform changes can alter molecular signaling to promote tumorigenesis. An active area in cancer research is uncovering the roles of ubiquitination on spliceosome assembly contributing to transcript diversity and expression of alternative isoforms. However, the effects of isoform changes on functionality of ubiquitination machineries (E1, E2, E3, E4, and deubiquitinating (DUB) enzymes) influencing onco- and tumor suppressor protein stabilities is currently understudied. Characterizing these changes could be instrumental in improving cancer outcomes via the identification of novel biomarkers and targetable signaling pathways. In this review, we focus on highlighting reported examples of direct, protein-coded isoform variation of ubiquitination enzymes influencing cancer development and progression in gastrointestinal (GI) malignancies. We have used a semi-automated system for identifying relevant literature and applied established systems for isoform categorization and functional classification to help structure literature findings. The results are a comprehensive snapshot of known isoform changes that are significant to GI cancers, and a framework for readers to use to address isoform variation in their own research. One of the key findings is the potential influence that isoforms of the ubiquitination machinery have on oncoprotein stability.

The role of ubiquitin signaling pathway on liver regeneration in rats

The ubiquitin signalling pathway is a large system associated with numerous intracellular mechanisms. However, its function in the liver regeneration process remains unknown. This particular study investigates the intracellular effect mechanisms of the ubiquitin signalling pathway. It also determines the differences in the expression of 88 genes belonging to the ubiquitin pathway using the RT-PCR array method. To conduct this research, three genes-that differed in the expression analysis were selected. Moreover, their proteins were analysed by western blot analysis while using Ki67 immunohistochemical analysis that determines proliferation rates by hour. It was determined that BRCA1 and BARD1, which are effective in DNA repair, play an active role at PH24. Similarly, Ube2t expression, which belongs to the Fanconi anaemia pathway associated with DNA repair, was also found to be high at PH12-72 h. In addition, it was revealed that the expressions of Anapc2, Anapc11, Cdc20 belonging to the APC/C^Cdc20 complex, which participate in cell cycle regulation, differed at different hours after PH. Expression of Mul1, which is involved in mitochondrial biogenesis and mitophagy mechanisms, peaked at PH12 under the observation. Considering the Mul1 gene expression difference, MUL1-mediated mitophagy and mitochondrial fission mechanism may be associated with liver regeneration. It was also determined that PARKIN-mediated mitophagy mechanisms are not active in 0-72 h of liver regeneration since PARKIN expression did not show a significant change in PH groups.

Knockdown of ubiquitin-conjugating enzyme E2T (UBE2T) suppresses lung adenocarcinoma progression via targeting fibulin-5 (FBLN5)

Lung adenocarcinoma (LUAD) is the main histological type of lung cancer, which is the leading cause of cancer-related deaths. Accumulating evidence has displayed that UBE2T is related to tumor progression. However, its role in LUAD has not been fully elucidated. The expression of UBE2T was detected in LUAD tissues by qRT-PCR, western blotting, and immunohistochemistry. UBE2T shRNAs were transfected into LUAD cells to analyze the consequent alteration in function through CCK-8 assay, Edu assay, transwell assay, and TUNEL staining. The potential mechanism of UBE2T was analyzed through GEPIA and verified using ChIP, EMSA, and GST pull-down assays. Furthermore, a xenograft mouse model was used to assess UBE2T function in vivo. Results showed that UBE2T level was significantly elevated in LUAD tissues and high UBE2T expression was associated with poor overall survival and disease-free survival. Results from the loss-of-function experiments in vitro showed that UBE2T modulated LUAD cell proliferation, migration, invasion, and apoptosis. The mechanism analysis demonstrated that silence of UBE2T increased FBLN5 expression and inhibited the activation of p-ERK, p-GSK3β, and β-catenin. Moreover, following knockdown of UBE2T, the cell proliferation, migration, and invasion were decreased, and sh-FBLN5 partially reverse the decrease. In in vivo experiments, it was found that UBE2T knockdown inhibits the tumor growth in LUAD. Immunohistochemically, there was a reduction in Ki67 and an increase in FBLN5 in UBE2T shRNA-treated tumor tissues. In conclusion, UBE2T might be a potential biomarker of LUAD, and targeting the UBE2T/FBLN5 axis might be a novel treatment strategy for LUAD.

UBCH5 Family Members Differentially Impact Stabilization of Mutant p53 via RNF128 Iso1 During Barrett's Progression to Esophageal Adenocarcinoma

BACKGROUND & AIMS

TP53 mutations underlie Barrett's esophagus (BE) progression to dysplasia and cancer. During BE progression, the ubiquitin ligase (E3) RNF128/GRAIL switches expression from isoform 2 (Iso2) to Iso1, stabilizing mutant p53. However, the ubiquitin-conjugating enzyme (E2) that partners with Iso1 to stabilize mutant p53 is unknown.

METHODS

Single-cell RNA sequencing of paired normal esophagus and BE tissues identified candidate E2s, further investigated in expression data from BE to esophageal adenocarcinoma (EAC) progression samples. Biochemical and cellular studies helped clarify the role of RNF128-E2 on mutant p53 stability.

RESULTS

The UBE2D family member 2D3 (UBCH5C) is the most abundant E2 in normal esophagus. However, during BE to EAC progression, loss of UBE2D3 copy number and reduced expression of RNF128 Iso2 were noted, 2 known p53 degraders. In contrast, expression of UBE2D1 (UBCH5A) and RNF128 Iso1 in dysplastic BE and EAC forms an inactive E2-E3 complex, stabilizing mutant p53. To destabilize mutant p53, we targeted RNF128 Iso1 either by mutating asparagine (N48, 59, and 101) residues to block glycosylation to facilitate β-TrCP1-mediated degradation or by mutating proline (P54 and 105) residues to restore p53 polyubiquitinating ability. In addition, either loss of UBCH5A catalytic activity, or disruption of the Iso1-UBCH5A interaction promoted Iso1 loss. Consequently, overexpression of either catalytically dead or Iso1-binding-deficient UBCH5A mutants destabilized Iso1 to degrade mutant p53, thus compromising the clonogenic survival of mutant p53-dependent BE cells.

CONCLUSIONS

Loss of RNF128 Iso2-UBCH5C and persistence of the Iso1-UBCH5A complex favors mutant p53 stability to promote BE cell survival. Therefore, targeting of Iso1-UBCH5A may provide a novel therapeutic strategy to prevent BE progression.

UBE2D3 contributes to myocardial ischemia-reperfusion injury by regulating autophagy in dependence of p62/SQSTM1

The impairment of autophagic flux has been widely recognized in myocardial ischemia-reperfusion (I/R) injury, but its underlying mechanism contributing to impaired autophagic flux is poorly understood. As celluar major degradation systems, autophagy and ubiquitin proteasome(UPS) participate in the multitudinous progression of disease by interactive relationship. Especially UBE2D3, the ubiquitin-binding enzyme E2 family, is closely related to the regulation impairment of autophagic flux under I/R in our study. Therefore, this study aims to further explore the regulatory mechanism of UBE2D3 in I/R induced autophagy. We determined interference with UBE2D3 alleviated injury of myocardial cells both in vivo and in vitro. Conversely, when inhibiting proteasome function by injecting MG-132, myocardial infarct size of rats became increasingly enhanced, along with the high expression levels of LDH and CK-MB in serum, compared with myocardial I/R injury without treatment of MG-132. This had been caused by UBE2D3 promoting p62/SQSTM1(p62) ubiquitination(Ub), which lead to worsen the impairment of autophagic flux induced by myocardial I/R injury. In addition, UBE2D3 could also participate in the regulation of autophagy by negatively regulating mTOR. But more surprisingly, this mechanism was independent of the known mTOR-beclin1 pathway. These results suggested that in myocardial I/R injury, UBE2D3 promoted p62 ubiquitination to aggravate the impairment of autophagic flux. Moreover, mTOR was also involved in its regulation of autophagic flux in a way escaped from beclin1.

Regulation of anti-tumorigenic pathways by the combinatory treatment of calcitriol and TGF-β in PC-3 and DU145 cells

Calcitriol and transforming growth factors beta (TGF-β) are involved in several biological pathways such as cell proliferation, differentiation, migration and invasion. Their cellular effects could be similar or opposite depending on the genetic target, cell type and context. Despite the reported association of calcitriol deficiency and disruption of the TGF-β pathway in prostate cancer and the well-known independent effects of calcitriol and TGF-βs on cancer cells, there is limited information regarding the cellular effects of calcitriol and TGF-β in combination. In this study, we in vitro analyze the combinatory effects of calcitriol and TGF-β on cell growth and apoptosis using PC-3 and DU145 human prostate cancer cell lines. Using high-throughput microarray profiling of PC-3 cells upon independent and combinatory treatments, we identified distinct transcriptional landscapes of each intervention, with a higher effect established by the combinatorial treatment, following by TGF-β1 and later by calcitriol. A set of genes and enriched pathways converge among the treatments, mainly between the combinatory scheme and TGF-β1, but the majority were treatment-specific. Of note, CYP24A1, IGFBP3, CDKN1A, NOX4 and UBE2D3 were significantly up-regulated upon the combinatorial treatment whereas CCNA1, members of the CT45A and APOBEC3 family were down-regulated. By public RNA signatures, we were able to confirm the regulation by the co-treatment over cell proliferation and cell cycle. We finally investigated the possible clinical impact of genes modulated by the combinatorial treatment using benchmark prostate cancer data. This comprehensive analysis reveals that the combinatory treatment impairs cell growth without affecting apoptosis and their combinatory actions might synergize and improved their individual effects to reprogram prostate cancer signaling.

The Molecular Basis of Ubiquitin-Conjugating Enzymes (E2s) as a Potential Target for Cancer Therapy

Ubiquitin-conjugating enzymes (E2s) are one of the three enzymes required by the ubiquitin-proteasome pathway to connect activated ubiquitin to target proteins via ubiquitin ligases. E2s determine the connection type of the ubiquitin chains, and different types of ubiquitin chains regulate the stability and activity of substrate proteins. Thus, E2s participate in the regulation of a variety of biological processes. In recent years, the importance of E2s in human health and diseases has been particularly emphasized. Studies have shown that E2s are dysregulated in variety of cancers, thus it might be a potential therapeutic target. However, the molecular basis of E2s as a therapeutic target has not been described systematically. We reviewed this issue from the perspective of the special position and role of E2s in the ubiquitin-proteasome pathway, the structure of E2s and biological processes they are involved in. In addition, the inhibitors and microRNAs targeting E2s are also summarized. This article not only provides a direction for the development of effective drugs but also lays a foundation for further study on this enzyme in the future.

The E2 ubiquitin-conjugating enzyme UbcH5c: an emerging target in cancer and immune disorders

Ubiquitination is a crucial post-translational modification (PTM) of proteins and regulates their stabilities and activities, thereby modulating multiple signaling pathways. UbcH5c, a member of the UbcH5 ubiquitin-conjugating enzyme (E2) protein family, engages in the ubiquitination of dozens of proteins and regulates nuclear factor kappa-B (NF-κB), p53 tumor suppressor, and several other essential signaling pathways. UbcH5c has been reported to be abnormally expressed in human cancer and immune disorders and is involved in the initiation and progression of these diseases. In this review, we mainly focus on UbcH5c structure, activity, signaling pathways, and its relevance to cancer and immune disorders. We end by integrating all known factors relating to UbcH5c inhibition as a potential cancer therapy method, and discuss associated challenges.

UBE2T promotes radiation resistance in non-small cell lung cancer via inducing epithelial-mesenchymal transition and the ubiquitination-mediated FOXO1 degradation

Radiation resistance affects survival in non-small-cell lung cancer (NSCLC) patients. Further exploration of mechanisms and targets is urgently needed. Using bioinformatic analyses, we found that UBE2T is associated with survival, tumor size, lymph node metastasis and distant metastasis. Then, real-time PCR and immunohistochemistry were performed to explore the differentially expressed genes between normal and NSCLC tissues. Furthermore, we used colony formation, EdU incorporation, scratch, transwell assays, flow cytometry, immunofluorescence and western blot to assess the role of UBE2T in vitro and in vivo. RNA-Seq and coimmunoprecipitation were used to explore the mechanism. The results showed that UBE2T promotes proliferation, migration, invasion, and radiation resistance in vitro and in vivo by accelerating the G2/M transition and inhibiting apoptosis. Mechanistically, UBE2T promotes epithelial-mesenchymal transition (EMT) via ubiquitination-mediated FOXO1 degradation and Wnt/β-catenin signaling pathway activation. Moreover, FOXO1 reversed radiation resistance and EMT. Therefore, UBE2T may be a potential target for enhancing radiotherapy sensitivity and serve as a biomarker to predict prognosis.

Systematic analysis and prediction model construction of alternative splicing events in hepatocellular carcinoma: a study on the basis of large-scale spliceseq data from The Cancer Genome Atlas

Growing evidence showed that alternative splicing (AS) event is significantly related to tumor occurrence and progress. This study was performed to make a systematic analysis of AS events and constructed a robust prediction model of hepatocellular carcinoma (HCC). The clinical information and the genes expression profile data of 335 HCC patients were collected from The Cancer Genome Atlas (TCGA). Information of seven types AS events were collected from the TCGA SpliceSeq database. Overall survival (OS) related AS events and splicing factors (SFs) were identified using univariate Cox regression analysis. The corresponding genes of OS-related AS events were sent for gene network analysis and functional enrichment analysis. Optimal OS-related AS events were selected by LASSO regression to construct prediction model using multivariate Cox regression analysis. Prognostic value of the prediction models were assessed by receiver operating characteristic (ROC) curve and KaplanMeir survival analysis. The relationship between the Percent Spliced In (PSI) value of OS-related AS events and SFs expression were analyzed using Spearman correlation analysis. And the regulation network was generated by Cytoscape. A total of 34,163 AS events were identified, which consist of 3,482 OS-related AS events. UBB, UBE2D3, SF3A1 were the hub genes in the gene network of the top 800 OS-related AS events. The area under the curve (AUC) of the final prediction model based on seven types OS-related AS events was 0.878, 0.843, 0.821 in 1, 3, 5 years, respectively. Upon multivariate analysis, risk score (All) served as the risk factor to independently predict OS for HCC patients. SFs HNRNPH3 and HNRNPL were overexpressed in tumor samples and were signifcantly associated with the OS of HCC patients. The regulation network showed prominent correlation between the expression of SFs and OS-related AS events in HCC patients. The final prediction model performs well in predicting the prognosis of HCC patients. And the findings in this study improve our understanding of the association between AS events and HCC.

Elevation of miR-191-5p level and its potential signaling pathways in hepatocellular carcinoma: a study validated by microarray and in-house qRT-PCR with 1,291 clinical samples

BACKGROUND

The miR-191-5p expression has been reported to increase in hepatocellular carcinoma (HCC), but its clinical value and exact role remain to be further clarified. Thus, a comprehensive analysis was performed in the current study to explore the underlying function of miR-191-5p in HCC.

METHODS

HCC-related expression data were collected to conduct a thorough analysis to determine the miR-191-5p expression and its clinical significance in HCC, including microarray data from the Gene Expression Omnibus and ArrayExpress database as well as quantitative real-time polymerase chain reaction (qRT-PCR) data of 178 matched clinical samples. The underlying relationship between miR-191-5p and HCC was also explored on the basis of a series of bioinformatics analyses.

RESULTS

The overall pooled meta-analysis showed an overexpression of miR-191-5p in the HCC samples (SMD=0.400, 95% CI=0.139-0.663, P=0.003), consistent with the detected result of the clinical HCC samples through the qRT-PCR analysis. Higher miR-191-5p levels were correlated with advanced TNM stages (III and IV), higher pathological grades, and metastasis. Functionally, 64 potential target genes were acquired for further mechanism analysis. Two pathways (p75 neurotrophin receptor and liver kinase B1-mediated signaling pathways), which were likely modulated by miR-191-5p, were regarded to be linked to the deterioration of HCC. Early growth response 1 and UBE2D3 were identified as the most likely targets for miR-191-5p in HCC and were commonly implied in the top enriched pathways and protein-protein network.

CONCLUSIONS

In summary, miR-191-5p may function as a tumor promoter miRNA of HCC, and the miR-191-5p inhibitor may contribute to the targeted HCC treatment in the future.

MicroRNA-939 inhibits cell proliferation via targeting LRSAM1 in Hirschsprung's disease

Background

Hirschsprung's disease (HSCR) is a common digestive disease caused by impaired development of neural crest cells. Some studies have revealed the roles of microRNA (miRNA) in various diseases. But the function of miRNA in HSCR needs further investigation.

Methods

We adopted qRT-PCR and immunoblot analyses to explore the relative expression of miR-939 and LRSAM1 in 80 HSCR bowel tissues and 80 normal bowel tissues. CCK-8 assay, transwell assay and flow cytometry were used to evaluate the function of miR-939 by overexpression of miR-939 in 293T, SK-N-BE(2), SH-SY5Y cell lines. The direct connection between miR-939 and LRSAM1 was validated by dual-luciferase reporter assay. We also investigated the autophagy level via immunoblot analyses.

Results

Mir-939 was significantly upregulated in HSCR tissues with decreased expression of LRSAM1. Overexpression of miR-939 suppressed cell proliferation without affecting cell apoptosis, cell cycle or cell migration. And LRSAM1 exerted similar function. Autophagy was impaired in HSCR tissues compared with control samples. Mir-939 did not inhibit the autophagy although it decreased the expression of LRSAM1.

Conclusions

Our study shows the potential function of mir-939 through regulating LRSAM1 in HSCR and infers that autophagy may also confer the risk of HSCR.

Investigating age‑induced differentially expressed genes and potential molecular mechanisms in osteosarcoma based on integrated bioinformatics analysis

Osteosarcoma (OS) is the most common primary bone malignancy. It predominantly occurs in adolescents, but can develop at any age. The age at diagnosis is a prognostic factor of OS, but the molecular basis of this remains unknown. The current study aimed to identify age-induced differentially expressed genes (DEGs) and potential molecular mechanisms that contribute to the different outcomes of patients with OS. Microarray data (GSE39058 and GSE39040) obtained from the Gene Expression Omnibus database and used to analyze age-induced DEGs to reveal molecular mechanism of OS among different age groups (<20 and >20 years old). Differentially expressed mRNAs (DEMs) were divided into up and downregulated DEMs (according to the expression fold change), then Gene Ontology function enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis were performed. Furthermore, the interactions among proteins encoded by DEMs were integrated with prediction for microRNA-mRNA interactions to construct a regulatory network. The key subnetwork was extracted and Kaplan-Meier survival analysis for a key microRNA was performed. DEMs within the subnetwork were predominantly involved in ‘ubiquitin protein ligase binding’, ‘response to growth factor’, ‘regulation of type I interferon production’, ‘response to decreased oxygen levels’, ‘voltage-gated potassium channel complex’, ‘synapse part’, ‘regulation of stem cell proliferation’. In summary, integrated bioinformatics was applied to analyze the potential molecular mechanisms leading to different outcomes of patients with OS among different age groups. The hub genes within the key subnetwork may have crucial roles in the different outcomes associated with age and require further analysis.

The prognostic significance of hTERT overexpression in cancers: A systematic review and meta-analysis

BACKGROUND

Human telomerase reverse transcriptase (hTERT) plays an important role in cancer progression. Recently, several clinical studies investigated how the overexpression of hTERT predicts the poor prognosis of solid tumors. However, the results were inconclusive, partly because of the small numbers of patients included.

METHOD

We systematically searched PubMed, Web of Science, and Embase to identify relevant studies until August 2017. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the association of hTERT expression and survival outcomes.

RESULTS

A total of 27studies enrolling 2530 solid tumor patients were included in this meta-analysis. There were strong significant associations between hTERT overexpression and all endpoints: overall survival (OS) (HR = 1.50, 95% CI: 1.31-1.73, P = .00), disease-free survival (HR = 1.84, 95% CI: 1.38-2.46; P = .00), and recurrence-free survival (HR = 1.79, 95% CI: 1.07-2.99; P = .028). In the subgroup analysis, it was found that the overexpression of hTERT induced poor OS in lung cancer (HR = 1.51, 95% CI: 1.21-1.89; P = .00).

CONCLUSION

Our comprehensive systematic review concluded that the overexpression of hTERT was associated with poor survival in human solid tumors. hTERT may be a valuable predictive biomarker for prognosis.

UBE2D3 gene overexpression increases radiosensitivity of EC109 esophageal cancer cells in vitro and in vivo

Ubiquitin-conjugating enzyme E2D3 (UBE2D3), a key component in ubiquitin (Ub) proteasome system, plays a crucial role in tumorigenesis. We previously found that it is bound to hTERT, and UBE2D3 could attenuate radiosensitivity of human breast cancer cells. Here we investigated a contributing role of UBE2D3 in radiosensitivity of esophageal squamous carcinoma. We demonstrated that the overexpression of UBE2D3 in esophageal squamous carcinoma cells (EC109) resulted in prolonged G1 phase and shortened G2/M phase after irradiation. UBE2D3 overexpression also decreased length of telomere and activity of telomerase. In addition, the overexpression of UBE2D3 increased mRNA expression but decreased protein levels of hTERT in both vitro and vivo systems. Compared with untreated cells, the treatment of UBE2D3 overexpressing cells with the specific proteasome inhibitor (MG132) could up-regulate hTERT. MG132 treatment of UBE2D3 overexpressed cells caused a clear and dramatic increase in the amount of ubiquitinated hTERT species. These findings indicate that UBE2D3 enhances radiosensitivity of EC109 cells by degradating hTERT through the ubiquitin proteolysis pathway.

Telomerase reverse transcriptase mediates EMT through NF-κB signaling in tongue squamous cell carcinoma

Locoregional lymph nodes metastasis in oral tongue squamous cell carcinoma represents one of important and common prognostic factors for poor clinical outcome. The human Telomerase Reverse Transcriptase (hTERT) is one of key players in cancer metastasis and stemness, but its exact function in tongue squamous cell carcinoma remains unknown. Here, we aim to understand the role of hTERT by utilizing the CRISPR/Cas9 gene editing system to deplete hTERT in the SCC-15 cell line. Functional comparison of SCC-15 control and knockout cells (hTERT^−/−) showed that loss of hTERT suppressed cell proliferation and migration/invasion. Furthermore, hTERT depletion significantly decreased tumorigenesis, including alterations in cellular morphology that areindicative for epithelial-mesenchymal transition (EMT). Mechanistically we demonstrated that the hTERT knockout attenuates NF-κB signaling via a negative feedback regulation in tumorprogression. From these results we propose a novel molecular mechanism of hTERT to promote SCC-15 invasion and metastasis via NF-κB activation. We conclude that targeting hTERT may represent a new therapeutic strategy to improve therapy and survival of tongue squamous cell carcinoma patients.

Concomitant underexpression of TGFBR2 and overexpression of hTERT are associated with poor prognosis in cervical cancer

The human telomerase reverse transcriptase (hTERT) is highly expressed in a variety of tumors. The transforming growth factor beta receptor type II (TGFBR2) is a downstream protein of transforming growth factor beta (TGF-β) which suppresses telomerase activity. However, the relevance of survival to the expression of TGFBR2, hTERT or TGFBR2/hTERT has not been previously investigated in cervical cancer tissues. Our study showed that patients with low level of TGFBR2 were associated with poor prognosis (HR = 1.704, P = 0.021), but no significant relevance between hTERT expression and survival (HR = 1.390, P = 0.181). However, a combination of low level of TGFBR2 and high level of hTERT was associated with a worse survival (HR = 1.892, P = 0.020), which had higher impact of hazard ratio (HR) on the overall survival (OS) than the low TGFBR2 expression alone. Knockdown of TGFBR2 expression by shRNA in Hela cells increased cell proliferation, cell invasion, G1/S transition and telomere homeostasis but decreased cell apoptosis. Overexpressing TGFBR2 and inhibiting hTERT suppressed Hela cell growth. These results would lead us to further explore whether a phenotype of TGFBR2^low/hTERT^high could be considered as a predictor of poor prognosis, and whether simultaneous use of TGFBR2 agonist and hTERT inhibitor could be developed as a therapeutic strategy.

Downregulation of Ubiquitin-conjugating Enzyme UBE2D3 Promotes Telomere Maintenance and Radioresistance of Eca-109 Human Esophageal Carcinoma Cells

Ubiquitin-conjugating enzyme UBE2D3 is an important member of the ubiquitin-proteasome pathways. Our previous study showed that the expression of UBE2D3 was negatively related to human telomerase reverse transcriptase (hTERT) and radioresistance in human breast cancer cells. However, in esophageal carcinoma, the exact effects and mechanisms of UBE2D3 in radioresistance remain unclear. This study shows that UBE2D3 knockdown was associated with significant increases in radioresistance to X-rays, telomerase activity, telomere length, and telomere shelterins. UBE2D3 knockdown-mediated radioresistance was related to a decrease in the spontaneous and ionizing radiation-induced apoptosis, resulting from a decrease in the Bax/Bcl-2 ratio. Furthermore, UBE2D3 downregulation was associated with increased G1-S phase transition and prolonged IR-induced G2/M arrest through over expression of cyclin D1, decrease of CDC25A expression and promotion of the ATM/ATR-Chk1-CDC25C pathway. Moreover, UBE2D3 downregulation reduced spontaneous DNA double-strand breaks and accelerated the repair of DNA damage induced by IR. The current data thus demonstrate that UBE2D3 downregulation enhances radioresistance by increased telomere homeostasis and prolonged IR-induced G2/M arrest, but decreases the IR-induced apoptosis and the number of DNA damage foci. These results suggest that UBE2D3 might be a potential molecular target to improve radiotherapy effects in esophageal carcinoma.

Ubiquitin proteasome system research in gastrointestinal cancer

The ubiquitin proteasome system (UPS) is important for the degradation of proteins in eukaryotic cells. It is involved in nearly every cellular process and plays an important role in maintaining body homeostasis. An increasing body of evidence has linked alterations in the UPS to gastrointestinal malignancies, including esophageal, gastric and colorectal cancers. Here, we summarize the current literature detailing the involvement of the UPS in gastrointestinal cancer, highlighting its role in tumor occurrence and development, providing information for therapeutic targets research and anti-gastrointestinal tumor drug design.