Is NEDD4-1 a negative regulator of phosphatase and tensin homolog in gastric carcinogenesis?

NEDD4 and NEDD4L: Ubiquitin Ligases Closely Related to Digestive Diseases

Protein ubiquitination is an enzymatic cascade reaction and serves as an important protein post-translational modification (PTM) that is involved in the vast majority of cellular life activities. The key enzyme in the ubiquitination process is E3 ubiquitin ligase (E3), which catalyzes the binding of ubiquitin (Ub) to the protein substrate and influences substrate specificity. In recent years, the relationship between the subfamily of neuron-expressed developmental downregulation 4 (NEDD4), which belongs to the E3 ligase system, and digestive diseases has drawn widespread attention. Numerous studies have shown that NEDD4 and NEDD4L of the NEDD4 family can regulate the digestive function, as well as a series of related physiological and pathological processes, by controlling the subsequent degradation of proteins such as PTEN, c-Myc, and P21, along with substrate ubiquitination. In this article, we reviewed the appropriate functions of NEDD4 and NEDD4L in digestive diseases including cell proliferation, invasion, metastasis, chemotherapeutic drug resistance, and multiple signaling pathways, based on the currently available research evidence for the purpose of providing new ideas for the prevention and treatment of digestive diseases.

Oncogenic Role of the NFATC2/NEDD4/FBP1 Axis in Cholangiocarcinoma

Nuclear factor of activated T cells 2 (NFATC2) is reported to contribute to the initiation and progression of various cancers; however, its expression and function in cholangiocarcinoma (CCA) tissues remain elusive. Herein, we investigated the expression pattern, clinicopathologic characteristics, cell biological functions, and potential mechanisms of NFATC2 in CCA tissues. Real-time reverse-transcription PCR (RT-qPCR) and immunohistochemistry were performed to analyze the expression of NFATC2 in human CCA tissues. Cell counting kit 8, colony formation, flow cytometry, Western blotting, and Transwell assays, and in vivo xenograft and pulmonary metastasis models, were used to explore the effect of NFATC2 on the proliferation and metastasis of CCA. A dual-luciferase reporter system, oligonucleotide pull-down, chromatin immunoprecipitation, immunofluorescence, and coimmunoprecipitation were performed to reveal the potential mechanisms. We found that NFATC2 was upregulated in CCA tissues and cells, and its aberrantly high levels were associated with a poorer differentiation pattern. Functionally, NFATC2 overexpression promoted CCA cell proliferation and metastasis, whereas knockdown of NFATC2 led to opposite result. Mechanistically, NFATC2 could be enriched in the promoter region of neural precursor cell-expressed developmentally downregulated protein 4 (NEDD4) to facilitate its expression. Furthermore, NEDD4 targeted fructose-1, 6-bisphosphatase 1 (FBP1) and inhibited FBP1 expression via ubiquitination. In addition, silencing NEDD4 rescued the effects of NFATC2 overexpression on CCA cells. NEDD4 was upregulated in human CCA tissues, and its expression levels were positively correlated with those of NFATC2. We thus conclude that NFATC2 promotes the progression of CCA via the NEDD4/FBP1 axis, emphasizing the oncogenic role of NFATC2 in CCA progression.

Targeting the E3 ligase NEDD4 as a novel therapeutic strategy for IGF1 signal pathway-driven gastric cancer

The IGF1 signal pathway is highly activated in some subtype of gastric cancer(GC) that exhibits poor survival and chemotherapy resistance. Although the results of clinical trials of anti-IGF1R monoclonal antibodies and IGF-1R inhibitors have been mostly disappointing in unselected cancer patients, some patients benefit from anti-IGF1R therapy in these failed studies. Therefore, it is necessary to characterize the complex IGF signaling in GC and help refine the strategies targeting the IGF1 pathway. We found that GC cell lines exhibit differential responses to the specific IGF1R inhibitor OSI906. According to the phosphorylation status of Akt upon the OSI906 treatment, we divided the GC cell lines into IGF1R-dependent and IGF1R-independent cells. Both in vitro and in vivo experiments indicate that Dox-induced knockdown of NEDD4 significantly suppresses tumor growth of IGF1R-dependent GC cells and NEDD4 overexpression promotes tumor growth of IGF1R-dependent GC cells. In contrast, the proliferation of IGF1R-independent GC cells is not affected by NEDD4 silencing and overexpression. The rescue experiments show that a PTEN-IRS1 axis is required for NEDD4-mediated regulation of Akt activation and tumor growth in GC cells. Clinically, NEDD4 is expressed higher in IGF1-high GC tissues compared with IGF1-low GC tissues and normal tissues, and the co-high expression of NEDD4 and IGF1 predicts a worse prognosis in GC patients. Taken together, our study demonstrated that NEDD4 specifically promotes proliferation of GC cells dependent on IGF1/IGF1R signaling by antagonizing the protein phosphatase activity of PTEN to IRS1, and targeting NEDD4 may be a promising therapeutic strategy for IGF1 signal pathway-driven gastric cancer.

Emerging roles of the HECT E3 ubiquitin ligases in gastric cancer

Gastric cancer (GC) is one of the most pernicious gastrointestinal tumors with extraordinarily high incidence and mortality. Ubiquitination modification of cellular signaling proteins has been shown to play important roles in GC tumorigenesis, progression, and prognosis. The E3 ubiquitin ligase is the crucial enzyme in the ubiquitination reaction and determines the specificity of ubiquitination substrates, and thus, the cellular effects. The HECT E3 ligases are the second largest E3 ubiquitin ligase family characterized by containing a HECT domain that has E3 ubiquitin ligase activity. The HECT E3 ubiquitin ligases have been found to engage in GC progression. However, whether HECT E3 ligases function as tumor promoters or tumor suppressors in GC remains controversial. In this review, we will focus on recent discoveries about the role of the HECT E3 ubiquitin ligases, especially members of the NEDD4 and other HECT E3 ligase subfamilies, in GC.

Down-regulated NEDD4L facilitates tumor progression through activating Notch signaling in lung adenocarcinoma

Neural precursor cell expressed developmentally down-regulated 4-like protein (NEDD4L), an E3 ubiquitin ligase, exerts an important role in diverse biological processes including development, tumorigenesis, and tumor progression. Although the role of NEDD4L in the pathogenesis of lung adenocarcinoma (LUAD) has been described, the mechanism by which NEDD4L promotes LUAD progression remains poorly understood. In the study, the correlation between NEDD4L level and clinical outcome in LUAD patients was analysed using the data from The Cancer Genome Atlas (TCGA) database. NEDD4L expression in LUAD cell lines and tissue samples was assessed through quantitative real-time PCR (qRT-PCR). The biological function of NEDD4L on regulating LUAD cell proliferation was tested with Cell Counting Kit-8 (CCK-8) assay in vitro, and mouse xenograft tumor model in vivo. We found that NEDD4L expression was significantly decreased in LUAD tissues and cell lines. Lower expression of NEDD4L exhibited a significantly poorer overall survival. Functionally, NEDD4L knockdown in H1299 cells accelerated cell growth, whereas NEDD4L overexpression in A549 cells repressed cell proliferation. NEDD4L overexpression also inhibited tumor xenograft growth in vivo. Mechanistically, NEDD4L decreased the protein stability of notch receptor 2 (Notch2) through facilitating its ubiquitination and degradation by ubiquitin-proteasome system. Consequently, NEDD4L negatively regulated Notch signaling activation in LUAD cells, and RO4929097 (a Notch inhibitor) treatment effectively repressed the effect of NEDD4L knockdown on LUAD cell proliferation. Taken together, these results demonstrate that down-regulated NEDD4L facilitates LUAD progression by activating Notch signaling, and NEDD4L may be a promising target to treat LUAD.

The biochemical and clinical implications of phosphatase and tensin homolog deleted on chromosome ten in different cancers

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is widely known as a tumor suppressor gene. It is located on chromosome 10q23 with 200 kb, and has dual activity of both protein and lipid phosphatase. In addition, as a targeted gene in multiple pathways, PTEN has a variety of physiological activities, such as those regulating the cell cycle, inducing cell apoptosis, and inhibiting cell invasion, etc. The PTEN gene have been identified in many kinds of cancers due to its mutations, deletions and inactivation, such as lung cancer, liver cancer, and breast cancer, and they are closely connected with the genesis and progression of cancers. To a large extent, the tumor suppressive function of PTEN is realized through its inhibition of the PI3K/AKT signaling pathway which controls cells apoptosis and development. In addition, PTEN loss has been associated with the prognosis of many cancers, such as lung cancer, liver cancer, and breast cancer. PTEN gene is related to many cancers and their pathological development. On the basis of a large number of related studies, this study describes in detail the structure, regulation, function and classical signal pathways of PTEN, as well as the relationship between various tumors related to PTEN. In addition, some drug studies targeting PTEN/PI3K/AKT/mTOR are also introduced in order to provide some directions for experimental research and clinical treatment of tumors.

NEDD4 Induces K48-Linked Degradative Ubiquitination of Hepatitis B Virus X Protein and Inhibits HBV-Associated HCC Progression

Neural precursor cell expressed developmentally downregulated gene 4 (NEDD4) plays two opposite roles in carcinogenesis. It has been reported that NEDD4 inhibits hepatocellular carcinoma (HCC) progression; however, little is known about its potential function and molecular mechanism in HCC in the context of hepatitis B virus (HBV) infection. In this study, we analyzed NEDD4 expression in 199 HCC specimens with or without HBV infection and observed that NEDD4 expression was unrelated to HBV exposure in HCC tumor tissue but that high NEDD4 expression conferred better overall survival (OS) and progression-free survival (PFS) than low NEDD4 expression in patients with HBV-associated HCC. Upregulation of NEDD4 inhibited proliferation, migration and invasion in HBV-related HCC cell lines. We demonstrated that NEDD4 interacts with HBV X protein (HBx) and that HBx upregulation could reverse the suppression of proliferation and mobility induced by NEDD4 overexpression. Furthermore, we confirmed that NEDD4 induced the degradation of HBx in a ubiquitin/proteasome-dependent manner via K48-linked ubiquitination. Our findings suggest that NEDD4 exerts a tumor-suppressive effect in HBV-associated HCC by acting as an E3 ubiquitin ligase for HBx degradation and provide new insights into the function of NEDD4.

Roles of E3 ubiquitin ligases in gastric cancer carcinogenesis and their effects on cisplatin resistance

Although gastric cancer (GC) is one of the most common cancers with high incidence and mortality rates, its pathogenesis is still not elucidated. GC carcinogenesis is complicated and involved in the activation of oncoproteins and inactivation of tumor suppressors. The ubiquitin-proteasome system (UPS) is crucial for protein degradation and regulation of physiological and pathological processes. E3 ubiquitin ligases are pivotal enzymes in UPS, containing various subfamily proteins. Previous studies report that some E3 ligases, including SKP2, CUL1, and MDM2, act as oncoproteins in GC carcinogenesis. On the other hand, FBXW7, FBXL5, FBXO31, RNF43, and RNF180 exert as tumor suppressors in GC carcinogenesis. Moreover, E3 ligases modulate cell growth, cell apoptosis, and cell cycle; thus, it is complicated to confer cisplatin resistance/sensitivity in GC cells. The intrinsic and acquired cisplatin resistance limits its clinical application against GC. In this review, we explore oncogenic and tumor suppressive roles of E3 ligases in GC carcinogenesis and focus on the effects of E3 ligases on cisplatin resistance in GC cells, which will provide novel therapeutic targets for GC therapy, especially for cisplatin-resistant patients.

NEDD4 E3 ligase: Functions and mechanism in human cancer

A growing amount of evidence indicates that the neuronally expressed developmentally downregulated 4 (NEDD4, also known as NEDD4-1) E3 ligase plays a critical role in a variety of cellular processes via the ubiquitination-mediated degradation of multiple substrates. The abnormal regulation of NEDD4 protein has been implicated in cancer development and progression. In this review article, we briefly delineate the downstream substrates and upstream regulators of NEDD4, which are involved in carcinogenesis. Moreover, we succinctly elucidate the functions of NEDD4 protein in tumorigenesis and progression, including cell proliferation, apoptosis, cell cycle, migration, invasion, epithelial mesenchymal transition (EMT), cancer stem cells, and drug resistance. The findings regarding NEDD4 functions are further supported by knockout mouse models and human tumor tissue studies. This review could provide a promising and optimum anticancer therapeutic strategy via targeting the NEDD4 protein.

A Propensity Score-adjusted Analysis of the Effects of Ubiquitin E3 Ligase Copy Number Variation in Peripheral Blood Leukocytes on Colorectal Cancer Risk

Background: The ubiquitin ligases E3 (E3s) plays a key role in the specific protein degradation in many carcinogenic biological processes. Colorectal cancer (CRC) development may be affected by the copy number variation (CNV) of E3s. Prior studies may have underestimated the impact of potential confounding factors' effects on the association between gene CNV and CRC risk, and CRC risk predictive model integrating gene CNV patterns is lacking. Our research sought to assess the genes CNVs of MDM2, SKP2, FBXW7, β-TRCP, and NEDD4-1 and CRC risk by using propensity score (PS) adjustment and developing models that integrate CNV patterns for CRC risk predictions.

Methods: This study comprising 1036 participants used traditional regression and different PS techniques to adjust the confounding factors to evaluate the relationships between five gene CNVs and CRC risk, and to establish a CRC risk predictive model. The AUC was applied to evaluate the effect of the model. The categorical net reclassification improvement (NRI) and the integrated discrimination improvement (IDI) were analyzed to evaluate the discriminatory accuracy improvement among the models.

Results: Compared to variable adjustment, the odds ratios (ORs) tended to be conservative and accurate with narrow confidence intervals (CIs) after PS adjustment. After PS adjustment, MDM2 amplification was related to increased CRC risk (Amp-pattern: OR = 8.684, 95% CI: 1.213-62.155, P = 0.031), whereas SKP2 deletion and the (del+amp) genotype were associated with reduced CRC risk (Del-pattern: OR = 0.323, 95% CI: 0.106-0.979, P = 0.046; Var-pattern: OR = 0.339, 95% CI: 0.135-0.854, P = 0.024). The predictive model integrating the gene CNV pattern could correctly reclassify 1.7% of the subjects.

Conclusions: MDM2 amplification and SKP2 CNVs are associated with increased and decreased CRC risk, respectively; abnormal CNV-integrated model is more precise for predicting CRC risk. Further studies are needed to verify these encouraging outcomes.

Upregulation of Neural Precursor Cell Expressed Developmentally Downregulated 4-1 is Associated with Poor Prognosis and Chemoresistance in Lung Adenocarcinoma

BACKGROUND

The E3 ubiquitin ligase neural precursor cell expressed developmentally downregulated 4-1 (NEDD4-1) negatively regulates phosphatase and tensin homolog deleted on chromosome 10 (PTEN) protein levels through polyubiquitination and proteolysis, but its significance in lung cancer is still unclear. This study investigated the expression and the role of NEDD4-1 in tumor development and chemosensitivity of lung adenocarcinoma (ADC).

METHODS

We retrospectively investigated the expression and significance of NEDD4-1, PTEN, and p-Akt proteins in 135 paired ADC and adjacent noncancerous tissue specimens using immunohistochemistry. Furthermore, we evaluated the relationship between NEDD4-1 expression and clinicopathologic characteristics and prognosis. The effects of small interfering RNA against NEDD4-1 on proliferation and chemosensitivity were examined in A549 cells in vitro using 3- (4,5-dimethylthiazol-2-yl) -5-(3-carboxymethoxyphenyl) -2-(4-sulfophenyl)- 2H-tetrazolium method. The ability of migration and invasion of A549 cells was tested by transwell assay. Moreover, reverse-transcription quantitative polymerase chain reaction and Western blotting analyses were used to determine the expression of NEDD4-1, PTEN, phosphoinositide 3-kinase (PI3K)/Akt activity, and its downstream target proteins.

RESULTS

NEDD4-1 protein was significantly upregulated in lung ADC tissues, whereas it was weak or negative in normal lung epithelial cells. The expression of NEDD4-1 in ADC (78.5%, 106/135) was significantly much higher than that in adjacent normal lung tissue (13.3%, 29/135, P < 0.01), and it was associated with lymph node metastasis, tumor-node-metastasis (TNM) stage, and chemotherapy resistance. PTEN expression was downregulated in lung ADC (60.7% vs. 100.0% in noncancerous specimens, P = 0.007), and was negatively correlated with lymph node metastasis, histological variants, clinical stage, chemoresistance. In addition, expression of p-Akt in ADC tissues (71.1% 96/135) was much higher than that in adjacent lung epithelial cells (6.7%, 9/135, P < 0.01). Kaplan-Meier and multivariate analysis demonstrated that expressions of NEDD4-1 and PTEN were both independent risk factors for survival in patients with lung ADC. NEDD4-1 knockdown in vivo decreased proliferation, migration, and invasion and improved chemosensitivity to cisplatin and paclitaxel in A549 cells. NEDD4-1 knockdown also significantly enhanced PTEN expression and inhibited p-Akt activity and downstream target proteins.

CONCLUSIONS

NEDD4-1 upregulation may contribute to the progression of lung ADC. NEDD4-1 may regulate the proliferation, invasion, migration, and chemoresistance of lung ADC cells through the PI3K/Akt pathway, suggesting that it may be regarded as a therapeutic target for the treatment of lung ADC.

Phosphorylation of phosphatase and tensin homolog induced by Helicobacter pylori promotes cell invasion by activation of focal adhesion kinase

Phosphorylation of the phosphatase and tensin homolog (PTEN) tumor suppressor at Ser380/Thr382/Thr383 residues is a novel mechanism underlying PTEN inactivation in gastric carcinogenesis, which may be triggered by Helicobacter pylori infection. To investigate this further, the effect of H. pylori infection on PTEN phosphorylation and the subsequent activation of focal adhesion kinase (FAK), were evaluated in gastric tissue samples from Mongolian gerbils and in the human gastric epithelial mucosa cell line GES-1 using immunohistochemistry, western blotting and Transwell assays. The in vivo and in vitro results of the present study demonstrated that H. pylori infection induced the phosphorylation and inactivation of PTEN at Ser380/Thr382/383, and the subsequent phosphorylation and activation of FAK at Tyr397. Gastric epithelial cell invasion was also increased. Furthermore, stable expression of a dominant-negative PTEN mutant inhibited the enhanced FAK activation and cell invasion induced by H. pylori infection. These results suggest that the mechanism underlying H. pylori-induced carcinogenesis may involve promoting cell invasion through the phosphorylation of PTEN and the activation of FAK.

Phosphorylation and inactivation of PTEN at residues Ser380/Thr382/383 induced by Helicobacter pylori promotes gastric epithelial cell survival through PI3K/Akt pathway

Phosphorylation of PTEN at residues Ser380/Thr382/383 leads to loss of phosphatase activity and tumor suppressor function. Here, we found that phosphorylation of PTEN at residues Ser380/Thr382/383 was increased with gastric carcinogenesis, and more importantly, Helicobacter pylori was a trigger of this modification in chronic non-atrophic gastritis. H. pylori could phosphorylate and inactivate PTEN in vivo and in vitro, resulting in survival of gastric epithelial cells. Furthermore, stable expression of dominant-negative mutant PTEN or inhibition of Akt prevented the enhanced survival induced by H. pylori. These results indicate that PTEN phosphorylation at residues Ser380/Thr382/383 is a novel mechanism of PTEN inactivation in gastric carcinogenesis, and H. pylori triggers this modification, resulting in activation of the PI3K/Akt pathway and promotion of cell survival.

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.

PTEN and NEDD4 in Human Breast Carcinoma

PTEN is an important tumor suppressor gene that antagonizes the oncogenic PI3K/AKT signaling pathway and has functions in the nucleus for maintaining genome integrity. Although PTEN inactivation by mutation is infrequent in breast cancer, transcript and protein levels are deficient in >25 % of cases. The E3 ubiquitin ligase NEDD4 (also known as NEDD4-1) has been reported to negatively regulate PTEN protein levels through poly-ubiquitination and proteolysis in carcinomas of the prostate, lung, and bladder, but its effect on PTEN in the breast has not been studied extensively. To investigate whether NEDD4 contributes to low PTEN levels in human breast cancer, we analyzed the expression of these proteins by immunohistochemistry across a large Swedish cohort of breast tumor specimens, and their transcript expression levels by microarrays. For both NEDD4 and PTEN, their transcript expression was significantly correlated to their protein expression. However, comparing NEDD4 expression to PTEN expression, either no association or a positive correlation was observed at the protein and transcript levels. This unexpected observation was further corroborated in two independent breast cancer cohorts from The Netherlands Cancer Institute and The Cancer Genome Atlas. Our results suggest that NEDD4 is not responsible for the frequent down-regulation of the PTEN protein in human breast carcinoma.

NEDD4: a promising target for cancer therapy

The Neuronally expressed developmentally downregulated 4 (NEDD4), functioning largely as an E3 ubiquitin ligase, has been demonstrated to play a critical role in the development and progression of human cancers. In this review, to understand the regulatory mechanism(s) of NEDD4 as well as the signaling pathways controlled by NEDD4, we briefly describe the NEDD4 upstream regulators and its downstream ubiquitin substrates. Moreover, we further discuss its oncogenic roles in human malignancies. Therefore, targeting NEDD4 could be a potential therapeutic strategy for treatment of human cancers.

SCF(β-TRCP)-mediated degradation of NEDD4 inhibits tumorigenesis through modulating the PTEN/Akt signaling pathway

The HECT domain-containing ubiquitin E3 ligase NEDD4 is widely expressed in mammalian tissues and plays a crucial role in governing a wide spectrum of cellular processes including cell growth, tissue development and homeostasis. Recent reports have indicated that NEDD4 might facilitate tumorigenesis through targeted degradation of multiple tumor suppressor proteins including PTEN. However, the molecular mechanism by which NEDD4 stability is regulated has not been fully elucidated. Here we report that SCF(β-TRCP) governs NEDD4 protein stability by targeting it for ubiquitination and subsequent degradation in a Casein Kinase-I (CKI) phosphorylation-dependent manner. Specifically, depletion of β-TRCP, or inactivation of CKI, stabilized NEDD4, leading to down-regulation of its ubiquitin target PTEN and subsequent activation of the mTOR/Akt oncogenic pathway. Furthermore, we found that CKIδ-mediated phosphorylation of Ser347 and Ser348 on NEDD4 promoted its interaction with SCF(β-TRCP) for subsequent ubiquitination and degradation. As a result, compared to ectopic expression of wild-type NEDD4, introducing a non-degradable NEDD4 (S347A/S348A-NEDD4) promoted cancer cell growth and migration. Hence, our findings revealed the CKI/SCF(β-TRCP) signaling axis as the upstream negative regulator of NEDD4, and further suggested that enhancing NEDD4 degradation, presumably with CKI or SCF(β-TRCP) agonists, could be a promising strategy for treating human cancers.

Nedd4-1 is an exceptional prognostic biomarker for gastric cardia adenocarcinoma and functionally associated with metastasis

Background

Gastric cardia adenocarcinoma (GCA) is the most aggressive subtype of gastric carcinoma. New molecular markers and therapeutic targets are needed for diagnosis, prognosis and treatment of GCA. This study is to establish the E3 ubiquitin ligase Nedd4-1 as a prognostic biomarker to predict the survival and guide the treatment of GCA patients.

Methods

Expression of Nedd4-1 in 214 GCA tumor samples was detected by immunohistochemistry staining (IHC) using tissue microarray assay (TMA). Association of Nedd4-1 with cumulative survival of the TNM stages I-III patients and clinicopathological characteristics was statistically analyzed. The role of Nedd4-1 in gastric cancer cell migration and invasion were determined by transwell and wound healing assays.

Results

Nedd4-1 is overexpressed in 83% of the GCA tumors. The 5-year survival rate in Nedd4-1 negative GCA patients is as high as 96%. Log-rank analysis indicated that overexpression of Nedd4-1 is inversely correlated with cumulative survival (χ² = 21.885, p <0.001). Multivariate logistic regression analysis showed that overexpression of Nedd4-1 is associated with an extremely low GCA survival rate with a hazard ratio (HR) = 0.068 (p = 0.008) in TNM stages I-III patients. Statistical analysis of association of Nedd4-1 overexpression with clinicopathological characteristics revealed that overexpression of Nedd4-1 is tightly associated with TNM stage (p < 0.001). Knockdown of Nedd4-1 in gastric cancer cell lines AGS and N87 dramatically inhibited the gastric cancer cell migration and invasion.

Conclusions

Our results indicate that Nedd4-1 is an exceptional prognostic biomarker for GCA and suggest that Nedd4-1 may play an essential role in GCA metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-248) contains supplementary material, which is available to authorized users.

Roles of PTEN (Phosphatase and Tensin Homolog) in gastric cancer development and progression

Gastric cancer is highly invasive, aggressively malignant, and amongst the most prevalent of all forms of cancer. Despite improved management strategies, early stage diagnosis of gastric cancer and accurate prognostic assessment is still lacking. Several recent reports have indicated that the pathogenesis of gastric cancer involves complex molecular mechanisms and multiple genetic and epigenetic alterations in oncogenes and tumor suppressor genes. Functional inactivation of the tumor suppressor protein PTEN (Phosphatase and Tensin Homolog) has been detected in multiple cases of gastric cancer, and already shown to be closely linked to the development, progression and prognosis of the disease. Inactivation of PTEN can be attributed to gene mutation, loss of heterozygosity, promoter hypermethylation, microRNA- mediated regulation of gene expression, and post-translational phosphorylation. PTEN is also involved in mechanisms regulating tumor resistance to chemotherapy. This review provides a comprehensive analysis of PTEN and its roles in gastric cancer, and emphasizes its potential benefits in early diagnosis and gene therapy-based treatment strategies.