Expression of A20 is reduced in pancreatic cancer tissues

Expanding the ubiquitin code in pancreatic cancer

The ubiquitin-proteasome system (UPS) is a fundamental regulatory mechanism in cells, vital for maintaining cellular homeostasis, compiling signaling transduction, and determining cell fates. These biological processes require the coordinated signal cascades of UPS members, including ubiquitin ligases, ubiquitin-conjugating enzymes, deubiquitinases, and proteasomes, to ubiquitination and de-ubiquitination on substrates. Recent studies indicate that ubiquitination code rewriting is particularly prominent in pancreatic cancer. High frequency mutation or aberrant hyperexpression of UPS members dysregulates ferroptosis, tumor microenvironment, and metabolic rewiring processes and contribute to tumor growth, metastasis, immune evasion, and acquired drug resistance. We conduct an in-depth overview of ubiquitination process in pancreatic cancer, highlighting the role of ubiquitin code in tumor-promoting and tumor-suppressor pathways. Furthermore, we review current UPS modulators and analyze the potential of UPS modulators as cancer therapy.

Clinical and Basic Evaluation of the Effects of Upregulated TNFAIP3 Expression on Colorectal Cancer

Objective

To assess the TNFAIP3 and nuclear factor κB (NFκB) protein expressions in colorectal cancer (CRC) tissue and to analyze the association of these proteins with the clinical pathological characteristics of CRC.

Methods

The following methods should be used in clinical trials: information collection and immunohistochemical methods. The following methods are used for cell experiment: cell transfection, CCK8 detection method, transwell experiment, and western blot experiment. Explore the TNFAIP3 expression in CRC cells, and assess the effect of upregulated TNFAIP3 expression on CRC cell proliferation, invasion, and migration. In clinical experiment, we selected the tumor tissues of 39 CRC patients as our experimental samples. We also collected corresponding patient demographics, such as sex, age, cell differentiation, tumor type, and lymph node metastasis. We also analyzed the TNFAIP3 and NFκB protein expressions in 20 experimental and 20 control samples and evaluated potential correlations between these two proteins and clinical pathological characteristics of CRC. For basic experiment, we established CRC cell lines with elevated TNFAIP3 expression and then randomly divided the cells into three groups, namely, TNFAIP3, NS, and Con groups. Using the transwell and CCK8 methods, we detected the CRC migration abilities and cell proliferation, respectively. We also employed western blot analysis to assess protein expression in the three groups.

Results

NFκB was highly expressed, and TNFAIP3 was scarcely expressed in the experimental group versus control. The expression of both these proteins were strongly related to the degree of tumor differentiation (P < 0.05). The TNFAIP3 and NFκB protein expressions were significantly associated with lymph node metastasis and tumor differentiation (P < 0.05). For basic experiment, compared to the Con and NS groups, TNFAIP3 protein expression levels, cell proliferation, invasion, and migration were significantly increased in the TNFAIP3 group (P < 0.05).

Conclusion

TNFAIP3 overexpression strongly inhibited CRC proliferation, invasion, and migration. Enhanced NFκB protein expression in CRC tissues was associated with elevated malignant degree, metastasis, and TNFAIP3 protein expression in patients who demonstrated high malignant degree and metastasis. Our evidences suggest the promising potential of utilizing TNFAIP3 and NFκB as important reference indices for determining the prognostic outcome of CRC. Furthermore, we revealed that TNFAIP3 overexpression inhibited CRC cell proliferation, invasion, and migration.

The dual roles of A20 in cancer

A20 is a prototypical anti-inflammatory molecule that is linked to multiple human diseases, including cancers. The role of A20 as a tumor suppressor was first discovered in B cell lymphomas. Subsequent studies revealed the dual roles of A20 in solid cancers. This review focuses on the roles of A20 in different cancer types to demonstrate that the effects of A20 are cancer type-dependent. A20 plays antitumor roles in colorectal carcinomas and hepatocellular carcinomas, whereas A20 acts as an oncogene in breast cancers, gastric cancers and melanomas. Moreover, the roles of A20 in the setting of glioma therapy are context-dependent. The action mechanisms of A20 in different types of cancer are summarized. Additionally, the role of A20 in antitumor immunity is discussed. Furthermore, some open questions in this rapidly advancing field are proposed. Exploration of the actions and molecular mechanisms of A20 in cancer paves the way for the application of A20-targeting approaches in future cancer therapy.

The prognostic evaluation of CA19-9, D-dimer and TNFAIP3/A20 in patients with pancreatic ductal adenocarcinoma

ABSTRACT

This study aimed to explore the significance and prognostic value of serum tumor-associated carbohydrate antigen 19-9 (CA19-9), D-dimer, and tumor necrosis factor alpha-induced protein 3 (TNFAIP3/A20) in patients with pancreatic ductal adenocarcinoma (PDAC).Our study included 148 patients treated for PDAC at Northern Jiangsu People's Hospital Affiliated to Yangzhou University from January 2012 to December 2016. Cutoff prognostic values were predicted using the receiver operating characteristic (ROC) curve. The Kaplan-Meier method was used to assess the survival rates of patients. Univariate and multivariate COX regression analyses were used to evaluate the prognostic factors.The recommended cutoff values of neutrophil-lymphocyte rate (NLR), platelet-lymphocyte rate (PLR), CA19-9, and D-dimer were 2.04 (sensitivity, 0.59; specificity, 0.9; area under the ROC curve [AUC], 0.749; P < .001), 52.94 (sensitivity, 0.73; specificity, 0.95; AUC, 0.829; P < .001), 176.66 U/mL (sensitivity, 0.7; specificity, 0.9; AUC, 0.794; P < .001), and 1.18 mg/L (sensitivity, 0.82; specificity, 0.9; AUC, 0.845; P < .001), respectively. Positive TNFAIP3/A20 expression was considered as an inclusion criterion. Serum CA19-9 expression was related with lymph node metastasis (P = .010), tumor-lymph node-metastasis (TNM) stage (P < .001), and survival rate (P < .001). D-dimer was correlated with tumor differentiation grade (P = .014), tumor size (P = .045), TNM stage (P < .001), and survival rate (P < .001). TNFAIP3/A20 was correlated with tumor differentiation grade (P < .001), body mass index (BMI) (P < .001), TNM stage (P = .014), and survival rate (P < .001). Kaplan-Meier curves showed that PDAC patients had significant differences in CA19-9, D-dimer, and TNFAIP3/A20 expressions (P < .05). CA19-9, D-dimer, TNM stage, tumor differentiation grade, and TNFAIP3/A20 were independent prognostic markers for PDAC in univariate and multivariate COX analyses.CA19-9, D-dimer, and TNFAIP3/A20 were found to be independent prognostic markers for PDAC patients.

A20 targets PFKL and glycolysis to inhibit the progression of hepatocellular carcinoma

Abnormal expression of the E3 ubiquitin ligase A20 has been found in some malignant cancers, including hepatocellular carcinoma (HCC). Here, we discovered that A20 is an E3 ubiquitin ligase for phosphofructokinase, liver type (PFKL) in HCC A20 interacts with PFKL and promotes its degradation, therefore inhibiting glycolysis in HCC cell lines. Downregulation of A20 in HCC cells promotes proliferation, migration, and glycolysis, all of which can be inhibited by targeting PFKL with RNA interference. Importantly, A20 is downregulated in advanced HCC tissues and inversely correlated with PFKL expression. Thus, our findings establish A20 as a critical regulator of glycolysis and reveal a novel mechanism for A20 in tumor suppression and PFKL regulation. Given that an increased level of glycolysis is linked with HCC, this study also identifies potential therapeutic targets for HCC treatment.

A20 inhibits the motility of HCC cells induced by TNF-α

Metastasis of hepatocellular carcinoma (HCC) can be facilitated by TNF-α, a prototypical inflammatory cytokine in the HCC microenvironment. A20 is a negative regulator of NF-κB signaling pathway. In the present study we ask whether A20 plays a role in HCC metastasis. We found that A20 expression was downregulated in the invasive cells of microvascular invasions (MVI) compared with the noninvasive cells in 89 tissue samples from patients with HCC by immunochemistry methods. Overexpression of A20 in HCC cell lines inhibited their motility induced by TNF-α. Furthermore, the overexpression of A20 inhibited epithelial-mesenchymal transition (EMT), FAK activation and RAC1 activity. By contrast, knockdown of A20 in one HCC cell line results in the converse. In addition, the overexpression of A20 restrained the formation of MVI in HCC xenograft in nude mice treated with TNF-α. All the results suggested that A20 functioned as a negative regulator in motility of HCC cells induced by TNF-α.

TNFα induces tolerant production of CXC chemokines in colorectal cancer HCT116 cells via A20 inhibition of ERK signaling

Ubiquitin editing enzyme A20 functions as a tumor suppressor in various cancer. However, the mechanism for A20 regulation of cancer progress is not fully understood. In this study, we found that in human colorectal cancer HCT116 cells, TNFα induced a tolerant production of CXC chemokines, including CXCL1, 2, and 8 in a dose and time dependent manner. TNFα pre-treatment of HCT116 cells down-regulated the chemokine production induced by TNFα re-treatment. TNFα induced the phosphorylation of MAPKs ERK, JNK, P38 and NF-κB P65, but only ERK inhibition decreased TNFα-induced chemokine production. Both RT-PCR and FACS results showed that TNFα treatment did not regulate the expression of TNF receptors. However, TNFα up-regulated the expression of A20 at both mRNA and protein levels significantly. TNFα pre-treatment inhibited the signal transduction of MAPKs induced by TNFα re-stimulation, and A20 over-expression decreased the signal transduction of ERK and P38. Meanwhile, A20 inhibition by RNA interference reversed chemokine down-regulation induced by TNFα re-stimulation after TNFα pre-treatment. Taken together, these results suggested that in human colorectal cancer cells, A20 may function to inhibit cancer progression via down-regulation of TNFα-induced chemokine production by suppression of ERK signaling.

TNFAIP3 overexpression is an independent factor for poor survival in esophageal squamous cell carcinoma

Tumor necrosis factor α induced protein 3 (TNFAIP3) is a protein that is induced by TNF-mediated NF-κB activation and has a dual function in regulating NF-κB. TNFAIP3 is associated with inflammatory carcinogenesis in many cancer types. However, the clinical significance of TNFAIP3 expression and function in esophageal squamous cell carcinoma (ESCC) has not yet been reported. We examined 149 ESCC tissue specimens to determine the clinical significance of TNFAIP3 by immunohistochemistry. Western blot analyses were used to detect TNFAIP3 expression in TE-1, TE-8, TE-15 and KYSE-70 ESCC cells and in Het-1A, a non-cancerous esophageal cell line. TNFAIP3 protein knockdown was conducted using small-interfering RNA to investigate its impact on cell proliferation, migration and invasion. Significant correlations between TNFAIP3 expression and differentiation (P=0.04) among clinicopathological characteristics of ESCC patients were demonstrated, and high TNFAIP3 expression was associated with poor survival (P=0.02). Moreover, multivariate analysis result showed that high TNFAIP3 expression was an independent factor for poor survival (P=0.04). In vitro analysis showed high expression of TNFAIP3 protein in TE-15 cells and low expression in Het-1A cells. Furthermore, the proliferation, migration and invasion of TE-15 cells after TNFAIP3 suppression by siRNA were significantly reduced. These findings suggest that TNFAIP3 protein may be an independent prognostic marker for poor survival, and a promising target for ESCC therapy.

A20 suppresses hepatocellular carcinoma proliferation and metastasis through inhibition of Twist1 expression

Background

Aberrant expression of A20 has been reported in several human malignancies including hepatocellular carcinoma (HCC). However, its clinical relevance and potential role in HCC remain unknown.

Methods

Quantitative PCR, Western blots and immunohistochemistry analyses were used to quantify A20 expression in HCC samples and cell lines. The correlation of A20 expression with clinicopathologic features was analyzed in a cohort containing 143 patients with primary HCC. Kaplan-Meier curves were used to evaluate the association between A20 expression and patient survival. Functional studies were performed to determine the effects of A20 on proliferation and metastasis of HCC cells in vitro and in vivo.

Results

Expression of A20 was increased in HCC tissues and cell lines. Increased expression of A20 was negatively correlated with the tumor size, TNM stage, tumor thrombus formation, capsular invasion and serum AFP levels. Patients with higher A20 expression had a prolonged disease-free survival and overall survival than those with lower A20 expression. Forced expression of A20 significantly inhibited the proliferative and invasive properties of HCC cells both in vitro and in vivo, whereas knockdown of A20 expression showed the opposite effects. Further studies revealed that expression of A20 was inversely correlated with Twist1 levels and NF-κB activity in HCC tissues and cell lines. A20-induced suppression of proliferation and migration of HCC cells were mainly mediated through inhibition of Twist1 expression that was regulated at least partly by A20-induced attenuation of NF-κB activity.

Conclusions

Our results demonstrate that A20 plays a negative role in the development and progression of HCC probably through inhibiting Twist1 expression. A20 may serve as a novel prognostic biomarker and potential therapeutic target for HCC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0454-6) contains supplementary material, which is available to authorized users.

Ursolic acid from Trailliaedoxa gracilis induces apoptosis in medullary thyroid carcinoma cells

Medullary thyroid carcinoma (MTC) originates from the C‑cells of the thyroid and is not sensitive to radiation or chemotherapy. Therefore, surgical removal of the tumor tissue in its entirety is the only curative treatment for MTC. The present study aimed to examine the potential mechanisms of action of extracts of Trailliaedoxa gracilis (TG; WW Smith & Forrest), a plant from the province of Sichuan, China, and of ursolic acid (UA), a pentacyclic triterpen present in TG, on the MTC‑SK MTC cell line. A total of 13 TG fractions and UA were examined in vitro for their effects on cell morphology, cell number, proliferation and rates of apoptosis. Reverse transcription‑quantitative polymerase chain reaction of nuclear factor‑κB essential modifier (NEMO) was performed to delineate the role of the apoptotic pathway following treatment with UA. TG and UA were examined in vivo in xenotransplanted MTC‑bearing severe combined immunodeficient mice. The TG fractions exhibited antiproliferative effects, with inhibition of mitochondrial activity in the tumor cells at concentrations, which caused no impairment of the normal control cells. The apoptotic rates of the MTC‑SK cells treated with the TG fractions and UA were determined, in which no marked tumor inhibition was observed in the treated MTC‑mice, and no change in the expression of NEMO was detected in the treated MTC‑SK cells. The observation of early‑onset activation of caspase 8 suggested that the responsible factor was linked to NEMO, an anti‑apoptotic protein. However, no differences in the mRNA transcription levels of NEMO were detected in MTC‑SK cells treated with UA, suggesting that this protein was not associated with the signal transducer and activator of transcription 3 pathway.

Overexpression of MALT1-A20-NF-κB in adult B-cell acute lymphoblastic leukemia

Background

A20 is a dual inhibitor of NF-κB activation and apoptosis in the tumor necrosis factor receptor 1 signaling pathway, and both are related to tumorigenesis. A20 is frequently inactivated by deletions and/or mutations in several B and T cell lymphoma subtypes; however, knowledge of the role of A20 in B-cell acute lymphoblastic leukemia (B-ALL) remains limited. In this study, we characterized the A20 gene expression pattern, the expression level of its upstream regulating factor MALT1, and its downstream target NF-κB in adult B-ALL.

Methods

The expression level of MALT1, A20 and NF-κB1 was detected in peripheral blood mononuclear cells (PBMCs) from 20 patients with adult B-ALL (including 12 de novo B-ALL and 8 refractory/relapse B-ALL cases), and nine patients with B-ALL in complete remission (CR) using real-time PCR. Sixteen healthy individuals served as controls.

Results

Significant A20 overexpression was found in the B-ALL (median: 13.489) compared with B-ALL CR (median: 3.755) (P = 0.003) patients and healthy individuals (median: 8.748) (P = 0.002), while there was no significant difference in A20 expression between B-ALL CR patients and healthy individuals (P = 0.107). Interestingly, the A20 expression level in the B-ALL samples was relatively different with approximately 50% of the B-ALL cases showing a relatively high A20 expression level, while the remaining 50% cases demonstrated slight upregulation or a similar expression level as the healthy controls. However, there was no significant difference in the A20 expression level between de novo B-ALL (median 12.252) and refractory/relapse B-ALL patients (median 21.342) (P = 0.616). Similarly, a significantly higher expression level of NF-κB1 was found in the B-ALL (median 1.062) patients compared with healthy individuals (median 0.335) (P < 0.0001), while the NF-κB1 expression level was downregulated in the B-ALL CR group (median 0.339), which was significantly lower than that in those with B-ALL (P = 0.001). Moreover, the MALT1 expression level in B-ALL was upregulated (median 1.938) and significantly higher than that in healthy individuals (median 0.677) (P = 0.002) and B-ALL CR patients (median 0.153) (P = 0.008). The correlation of the expression levels of all three genes was lost in B-ALL.

Conclusions

We found that MALT1-A20-NF-κB is overexpressed in adult B-ALL, which may be related to the pathogenesis of B-ALL, and this pathway may be considered a potentially attractive target for the development of B-ALL therapeutics.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0222-0) contains supplementary material, which is available to authorized users.

Functional effect of polymorphisms in the promoter of TNFAIP3 (A20) in acute pancreatitis in the Han Chinese population

BACKGROUND

The zinc finger protein A20 is an important negative regulator of inflammation; polymorphisms in the corresponding gene, TNFAIP3, have been reported to be associated with several inflammation diseases. However, only a few studies have focused on the relationship between TNFAIP3 polymorphisms and acute pancreatitis (AP).

METHODS

We enrolled 201 healthy controls and 190 acute pancreatitis patients (including 47 systemic inflammatory response syndrome patients) for this study and used DNA sequencing to investigate polymorphisms in the TNFAIP3 promoter. The functional effects of these variants on transcriptional activity, A20 expression, NF-κB activity, and TNF-α and IL-1β levels, after in vitro lipopolysaccharide stimulation, were assessed.

RESULTS

Two SNPs (rs59693083 and rs5029924) in the TNFAIP3 promoter were selected based on bioinformatic analysis. Neither of these SNPs was associated with susceptibility to AP; however, acute pancreatitis patients who possessed the T allele of rs5029924 were more likely to experience systemic inflammatory response syndrome. Moreover, rs5029924 was found to affect TNFAIP3 promoter activity. After lipopolysaccharide stimulation, the expression of A20 protein significantly decreased, while the activity of NF-κB and the production of TNF-α and IL-1β significantly increased in whole blood leukocytes from subjects with the T allele.

CONCLUSION

The rs5029924 polymorphism in the TNFAIP3 promoter may alter the risk of systemic inflammatory response syndrome in acute pancreatitis patients by influencing the expression of A20 protein.

Genetic variation and alterations of genes involved in NFκB/TNFAIP3- and NLRP3-inflammasome signaling affect susceptibility and outcome of colorectal cancer

Colorectal tumors are continuously exposed to an inflammatory environment, which together with mitogenic signals sustain several cancer hallmarks. Nuclear factor-kappa B (NFκB) is a major regulator of inflammation and variation in NFκB-associated genes could potentially be used as biomarkers to identify patients with increased risk of colorectal cancer (CRC) development, and/or a rapidly progressing disease. In this study, 348 CRC cases and 806 randomly selected healthy individuals from southeastern Sweden were examined with regard to seven polymorphisms in NFκB pathway-associated genes. Log-rank-tests and Cox proportional hazard regression analysis examined the association between the polymorphisms and CRC-specific survival, whereas chi-square tests and logistic regression analysis were used to test for associations between the polymorphisms and CRC susceptibility. Gene expression and loss of heterozygosity analyses of TNFAIP3 were carried out in a subset of tumors to assess its role as a tumor suppressor in CRC. Heterozygous and polymorphic TNFAIP3 (rs6920220), heterozygous NLRP3 (Q705K) and polymorphic NFκB -94 ATTG ins/del genotypes were found to be associated with poorer survival in patients diagnosed with invasive CRC (aHR = 5.2, 95% CI: 2.5-10.9, P < 0.001). TNFAIP3 mRNA levels were significantly decreased in tumors compared with adjacent non-neoplastic mucosa (P < 0.0001) and loss of heterozygosity of 6q23.3 (TNFAIP3) was detected in 17% of cases, whereas only 2.5% of the investigated specimens displayed TNFAIP3 gene mutations. We propose that TNFAIP3 (rs6920220), NLRP3 (Q705K) and NFκB -94 ATTG ins/del polymorphisms are associated with poor survival in patients with advanced CRC and may be used as prognostic markers. Experimental results indicate that TNFAIP3 may act as a tumor suppressor in CRC.