Nedd4L modulates the transcription of metalloproteinase-1 and -13 genes to increase the invasive activity of gallbladder cancer

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.

NEDD4L in human tumors: regulatory mechanisms and dual effects on anti-tumor and pro-tumor

Tumorigenesis and tumor development are closely related to the abnormal regulation of ubiquitination. Neural precursor cell expressed developmentally downregulated 4-like (NEDD4L), an E3 ubiquitin ligase critical to the ubiquitination process, plays key roles in the regulation of cancer stem cells, as well as tumor cell functions, including cell proliferation, apoptosis, cell cycle regulation, migration, invasion, epithelial-mesenchymal transition (EMT), and tumor drug resistance, by controlling subsequent protein degradation through ubiquitination. NEDD4L primarily functions as a tumor suppressor in several tumors but also plays an oncogenic role in certain tumors. In this review, we comprehensively summarize the relevant signaling pathways of NEDD4L in tumors, the regulatory mechanisms of its upstream regulatory molecules and downstream substrates, and the resulting functional alterations. Overall, therapeutic strategies targeting NEDD4L to treat cancer may be feasible.

NEDD4L inhibits migration, invasion, cisplatin resistance and promotes apoptosis of bladder cancer cells by inactivating the p62/Keap1/Nrf2 pathway

PURPOSE

This study identified the function of neural precursor cell expressed developmentally down-regulated 4-like (NEDD4L) on bladder cancer (BLCA).

METHODS

NEDD4L expression in BLCA patients was scrutinized. The function of NEDD4L on the viability, apoptosis, migration and invasion of BLCA cells was evaluated by cell counting kit-8, flow cytometry and Transwell assays. The effect of NEDD4L on the cisplatin (DDP) resistance of the DDP-resistant BLCA cells was explored. The influence of NEDD4L on the p62/Keap1/Nrf2 pathway activity in BLCA cells was tested by Western blot. Rescue experiments were implemented to verify whether NEDD4L regulated BLCA cell malignant behavior by mediating the Keap1/Nrf2 pathway activity via p62. The effect of NEDD4L on the growth and the p62/Keap1/Nrf2 pathway activity in vivo was researched in xenograft tumor nude mice models.

RESULTS

The down-regulated NEDD4L in BLCA patients was associated with unfavorable survival. NEDD4L suppressed the viability (inhibition rate 57.1%/49.0%), migration (inhibition rate 49.7%/77.1%), invasion (inhibition rate 50.6%/75.7%), promoted the apoptosis of T24/5637 cells (promotion rate 243.8%/201.9%), reduced IC 50 of DDP-resistant T24/5637 cells from 132.2/101.8 to 57.81/59.71 μM, respectively, and inactivated the p62/Keap1/Nrf2 pathway in T24/5637 cells. p62 up-regulation partially abrogated the inhibition of NEDD4L on the Keap1/Nrf2 pathway activity, the malignant behavior of BLCA cells, and the DDP resistance of DDP-resistant BLCA cells. NEDD4L overexpression inhibited the tumor growth and the p62/Keap1/Nrf2 pathway activity in vivo in BLCA.

CONCLUSION

NEDD4L inhibits the progression of BLCA by inactivating the p62/Keap1/Nrf2 pathway. It may be an effective target for BLCA treatment.

The role of NEDD4 related HECT-type E3 ubiquitin ligases in defective autophagy in cancer cells: molecular mechanisms and therapeutic perspectives

The homologous to the E6-AP carboxyl terminus (HECT)-type E3 ubiquitin ligases are the selective executers in the protein ubiquitination, playing a vital role in modulation of the protein function and stability. Evidence shows the regulatory role of HECT-type E3 ligases in various steps of the autophagic process. Autophagy is an intracellular digestive and recycling process that controls the cellular hemostasis. Defective autophagy is involved in tumorigenesis and has been detected in various types of cancer cells. A growing body of findings indicates that HECT-type E3 ligases, in particular members of the neural precursor cell expressed developmentally downregulated protein 4 (NEDD4) including NEDD4-1, NEDD4-L, SMURFs, WWPs, and ITCH, play critical roles in dysregulation or dysfunction of autophagy in cancer cells. The present review focuses on NEDD4 E3 ligases involved in defective autophagy in cancer cells and discusses their autophagic function in different cancer cells as well as substrates and the signaling pathways in which they participate, conferring a basis for the cancer treatment through the modulating of these E3 ligases.

Unraveling the Potential Role of NEDD4-like E3 Ligases in Cancer

Cancer is a deadly disease worldwide, with an anticipated 19.3 million new cases and 10.0 million deaths occurring in 2020 according to GLOBOCAN 2020. It is well established that carcinogenesis and cancer development are strongly linked to genetic changes and post-translational modifications (PTMs). An important PTM process, ubiquitination, regulates every aspect of cellular activity, and the crucial enzymes in the ubiquitination process are E3 ubiquitin ligases (E3s) that affect substrate specificity and must therefore be carefully regulated. A surfeit of studies suggests that, among the E3 ubiquitin ligases, neuronal precursor cell-expressed developmentally downregulated 4 (NEDD4)/NEDD4-like E3 ligases show key functions in cellular processes by controlling subsequent protein degradation and substrate ubiquitination. In addition, it was demonstrated that NEDD4 mainly acts as an oncogene in various cancers, but also plays a tumor-suppressive role in some cancers. In this review, to comprehend the proper function of NEDD4 in cancer development, we summarize its function, both its tumor-suppressive and oncogenic role, in multiple types of malignancies. Moreover, we briefly explain the role of NEDD4 in carcinogenesis and progression, including cell survival, cell proliferation, autophagy, cell migration, invasion, metastasis, epithelial-mesenchymal transition (EMT), chemoresistance, and multiple signaling pathways. In addition, we briefly explain the significance of NEDD4 as a possible target for cancer treatment. Therefore, we conclude that targeting NEDD4 as a therapeutic method for treating human tumors could be a practical possibility.

Targeting matrix metalloproteinases by E3 ubiquitin ligases as a way to regulate the tumor microenvironment for cancer therapy

The tumor microenvironment (TME) plays an important role in neoplastic development. Matrix metalloproteinases (MMPs) are critically involved in tumorigenesis by modulation of the TME and degradation of the extracellular matrix (ECM) in a large variety of malignancies. Evidence has revealed that dysregulated MMPs can lead to ECM damage, the promotion of cell migration and tumor metastasis. The expression and activities of MMPs can be tightly regulated by TIMPs, multiple signaling pathways and noncoding RNAs. MMPs are also finely controlled by E3 ubiquitin ligases. The current review focuses on the molecular mechanism by which MMPs are governed by E3 ubiquitin ligases in carcinogenesis. Due to the essential role of MMPs in oncogenesis, they have been considered the attractive targets for antitumor treatment. Several strategies that target MMPs have been discovered, including the use of small-molecule inhibitors, peptides, inhibitory antibodies, natural compounds with anti-MMP activity, and RNAi therapeutics. However, these molecules have multiple disadvantages, such as poor solubility, severe side-effects and low oral bioavailability. Therefore, it is necessary to discover the novel inhibitors that suppress MMPs for cancer therapy. Here, we discuss the therapeutic potential of targeting E3 ubiquitin ligases to inhibit MMPs. We hope this review will stimulate the discovery of novel therapeutics for the MMP-targeted treatment of a variety of human cancers.

Insights Into the Biological Role of NEDD4L E3 Ubiquitin Ligase in Human Cancers

Neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) is an E3 ubiquitin ligase that has been reported to participate in multiple cellular procedures by regulating of substrate ubiquitination and subsequent protein degradation. A great amount of evidence has demonstrated that NEDD4L mainly functions as a tumor suppressor in most cancer types, while it also acts as an oncogene in a few cancers. In this review, we summarize the potential role of NEDD4L in carcinogenesis and the related underlying molecular mechanism to improve our understanding of its functions in the tumorigenesis of human malignancies. Developing clinical drugs targeting NEDD4L could be a potential therapeutic strategy for cancer therapy in the future.

Pan-cancer Analysis of NEDD4L and Its Tumor Suppressor Effects in Clear Cell Renal Cell Carcinoma

The expression level of NEDD4L, an E3 ubiquitin ligase, has changed significantly in human cancers. In this study, we aimed to study the expression of NEDD4L in pan-carcinoma and its function in malignant tumors. We analyzed the gene expression level of NEDD4L in pan-cancer from The Cancer Genome Atlas (TCGA) microarray data set, the correlation between gene expression and overall survival, disease-specific survival, and tumor immune microenvironment changes. NEDD4L expression changes in half of the cancer types. Low expression of NEDD4L gene predicts poor overall survival and disease-specific survival (DSS) in renal clear cell carcinoma (KIRC) and renal chromophobe cell carcinoma (KIRP). NEDD4L is negatively related to interstitial cell infiltration and immune cell infiltration in most common cancers. Furthermore, the low expression of NEDD4L was verified in our clear cell renal cell carcinoma (ccRCC) clinical tissues. In ccRCC cells, NEDD4L overexpression significantly reduced cell proliferation and migration. In the functional analysis, we proved that NEDD4L could inhibit ERBB3 and MAPK signaling pathways. When cells are deficient in nutrition, NEDD4L promoted the degradation of the autophagy regulatory protein ULK1. Our study provides novel insights into the role of NEDD4L in pan-cancer. NEDD4L may play a tumor suppressor effect in ccRCC, through tumor immune regulation and ubiquitination of key intracellular kinases.

Integrated bioinformatics analysis of the NEDD4 family reveals a prognostic value of NEDD4L in clear-cell renal cell cancer

The members of the Nedd4-like E3 family participate in various biological processes. However, their role in clear cell renal cell carcinoma (ccRCC) is not clear. This study systematically analyzed the Nedd4-like E3 family members in ccRCC data sets from multiple publicly available databases. NEDD4L was identified as the only NEDD4 family member differentially expressed in ccRCC compared with normal samples. Bioinformatics tools were used to characterize the function of NEDD4L in ccRCC. It indicated that NEDD4L might regulate cellular energy metabolism by co-expression analysis, and subsequent gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. A prognostic model developed by the LASSO Cox regression method showed a relatively good predictive value in training and testing data sets. The result revealed that NEDD4L was associated with biosynthesis and metabolism of ccRCC. Since NEDD4L is downregulated and dysregulation of metabolism is involved in tumor progression, NEDD4L might be a potential therapeutic target in ccRCC.

Downregulation of MicroRNA-494 inhibits the TGF-β1/Smads signaling pathway and prevents the development of hypospadias through upregulating Nedd4L

BACKGROUND

Hypospadias, as a congenital disorder of the urethra, is the second most common birth abnormality of the male reproductive system. This study primarily investigates the effects of microRNA-494 (miR-494) on the transforming growth factor-β1 (TGF-β1)/Smads signaling pathway and on the development of hypospadias by binding to neural precursor cell expressed developmentally downregulated gene 4-like (Nedd4L).

METHODS

We induced a mouse model of hypospadias through di-(2-ethylhexyl) phthalate treatment. The underlying regulatory mechanisms of miR-494 in this model were analyzed upon treatment of miR-494 mimic, miR-494 inhibitor, or small interfering RNA against Nedd4L in urethral epithelial cells isolated from mice with hypospadias. We then verified the binding site between miR-494 and Nedd4L and applied a gain- and loss-of-function approach to determine the effects of miR-494 on cell proliferation, cycle distribution, and apoptosis.

RESULTS

Male mice with hypospadias exhibited significantly higher miR-494 expression and lower Nedd4L expression in urethral tissues than normal male mice. Nedd4L was verified as a target gene of miR-494. Treatment with miR-494 inhibitor suppressed the activation of the TGF-β1/Smads signaling pathway, whereas down-regulation of miR-494 exerted protective effects on urethral epithelial cells by impeding cell proliferation and inducing cell apoptosis.

CONCLUSIONS

The study indicates that downregulation of miR-494 inhibits the TGF-β1/Smads signaling pathway and prevents the development of hypospadias through upregulating Nedd4L.

Decreased expression of NEDD4L contributes to NSCLC progression and metastasis

Recent evidence indicated that neural precursor cell expressed, developmentally down-regulated 4-like (NEDD4L) has a critical role in the regulation of cellular processes such as apoptosis, transport and metastasis, and is downregulated in several types of cancers. However, the role of NEDD4L in non-small cell lung cancer (NSCLC) has not been fully elucidated. In this study, we demonstrated that NEDD4L was downregulated in NSCLCs. This downregulation correlated with lymph node invasion, advanced stage and poor survival. In vitro experiments revealed that NEDD4L significantly suppressed cell proliferation, migration and invasion abilities. Further in vivo assay demonstrated that knocking down of NEDD4L enhanced the tumor metastasis of NSCLC cells. Moreover, we found that Polycomb group protein enhancer of zeste homologue 2 (EZH2) mediated H3K27 methylation was involved in the downregulation of NEDD4L. Knocking down of EZH2 restored the expression of NEDD4L. Further examined by luciferase reporter assay indicated the EZH2 regulated the transcription activity of NEDD4L. In clinical samples, EZH2 was inversely correlated with NEDD4L expression. In summary, NEDD4L acted as a tumor suppressor gene in NSCLC and targeting EZH2 could upregulate NEDD4L expression, which might serve as a novel approach for NSCLC.

The correlation between NEDD4L and HIF-1α levels as a gastric cancer prognostic marker

NEDD4L (neural precursor cell expressed developmentally down-regulated 4-like) protein is a member of ubiquitin ligases Nedd4 family. Although studies have shown that Nedd4L may act as a tumor suppressor in various cancers, including gastric cancer (GC), its clinical significance and the diagnostic value in GC is not well defined. HIF-1α (hypoxia inducible factor family of transcription factors) is actively involved in the metabolism of many tumors, although the relationship between its expression levels and clinical significance in GC still need to be established. In this study, the level of HIF-1α and NEDD4L mRNA and protein in 25 freshly frozen GC- and matched normal-tissues were determined by western blot and quantitative PCR (qPCR). Additionally, immunohistochemistry assay was performed to measure the protein level of NEDD4L and HIF-1α in 124 GC and 25 normal control tissues. We observed that the NEDD4L mRNA and protein levels decreased significantly (P < 0.001) in GC tissues, while that of HIF-1α increased (P < 0.001), and they both were associated with a poor prognosis, as was the case in patients with lower NEDD4L and higher HIF-1α expression (P < 0.001). On correlation analysis, a significantly negative relationship (r = 0.288, P < 0.01) was revealed between NEDD4L and HIF-1α expressions. Multivariate analysis revealed that co-expression of NEDD4L (P < 0.05) and HIF-1α (P < 0.001) were independent predictors of GC prognosis. Thus, the correlation of NEDD4L and HIF-1α levels may act as a prognostic marker of GC.

Neural precursor cell-expressed developmentally down-regulated 4-like: a new biomarker in the pathophysiology of endometrial cancer

Objectives

Endometrial cancer is the most frequent tumor of the female genital tract. Ubiquitin is a small protein (8.5 kDa) found in all eukaryotic cells, binds to substrate proteins via a three-phase enzymatic pathway referred to as ubiquitination and plays an important role in cellular stability. Neural precursor cell-expressed developmentally down-regulated 4-like (NEDD4L) functions in the last phase of this enzymatic process. In this study, we investigated NEDD4L protein expression in endometrial cancer.

Methods

The study participants were divided into patients with benign endometrial pathologies (Group 1, n = 23), patients with endometrial hyperplasia (Group 2, n = 21) and patients with endometrial cancer (Group 3, n = 20). NEDD4L expression was detected by immunohistochemical staining and H scores were calculated to standardize staining intensity. Statistical analysis was performed using SPSS 16.0.

Results

NEDD4L expression levels according to H scores were significantly lower in patients diagnosed with endometrial cancer compared with those with benign endometrial pathologies.

Conclusion

NEDD4L is involved in maintaining cell stability, and reduced NEDD4L expression as a result of gene mutation may disrupt this balance in favor of tumorigenesis.

Downregulation of Nedd4L predicts poor prognosis, promotes tumor growth and inhibits MAPK/ERK signal pathway in hepatocellular carcinoma

Accumulating evidence indicates that the neural precursor cell-expressed, developmentally downregulated 4-like (Nedd4L) related with some tumor progression pathways and was found abnormally expressed in several kinds of solid cancers. However, the role and mechanism of Nedd4L in HCC remain unknown. This study was to assess the role of Nedd4L in HCC tumorigenesis and prognosis. The real-time quantitative RT-PCR and immunohistochemistry results revealed that Nedd4L was downregulated in HCC tissues compared to corresponding peri-noncancerous tissue, and HCC patients with low expression of Nedd4L exhibited poor prognosis assessed by Kaplan-Meier and Cox regression analysis in 78 HCC patients. Furthermore, knockdown of Nedd4L could significantly promote proliferation of HCC cells by CCK-8 and colony formation assays in vitro; whereas ectopic expression of Nedd4L resulted in attenuating proliferation in vitro and tumor growth in vivc determined by nude mice xenografts model. Mechanically, Nedd4L could phosphorylate ERK1/2 and regulate genes related with apoptosis. Collectively, Nedd4L plays a tumor suppressive role in HCC, possibly through triggering MAPK/ERK-mediated apoptosis, and Nedd4L downregulation may be a potential prognostic biomarker as well as a therapeutic target for HCC.

Nedd4L expression is decreased in ovarian epithelial cancer tissues compared to ovarian non-cancer tissue

AIM

Recent studies have demonstrated that the neural precursor cell expressed, developmentally downregulated 4-like (Nedd4L) gene plays a role in the progression of various cancers. However, reports describing Nedd4L expression in ovarian cancer tissues are limited.

MATERIAL AND METHODS

A cohort (n = 117) of archival formalin-fixed, paraffin embedded resected normal ovarian epithelial tissues (n = 10), benign ovarian epithelial tumor tissues (n = 10), serous borderline ovarian epithelial tumor tissues (n = 14), mucous borderline ovarian epithelial tumor tissues (n = 11), and invasive ovarian epithelial cancer tissues (n = 72) were assessed for Nedd4L protein expression using immunohistochemistry.

RESULTS

Nedd4L protein expression was significantly decreased in invasive ovarian epithelial cancer tissues compared to non-cancer tissues (P < 0.05). Decreased Nedd4L protein expression correlated with clinical stage, pathological grade, lymph node metastasis and survival (P < 0.05).

CONCLUSION

Nedd4L protein expression may be an independent prognostic marker of ovarian cancer development.

DDB2 modulates TGF-β signal transduction in human ovarian cancer cells by downregulating NEDD4L

The expression of DNA damage-binding protein 2 (DDB2) has been linked to the prognosis of ovarian cancer and its underlying transcription regulatory function was proposed to contribute to the favorable treatment outcome. By applying gene microarray analysis, we discovered neural precursor cell expressed, developmentally downregulated 4-Like (NEDD4L) as a previously unidentified downstream gene regulated by DDB2. Mechanistic investigation demonstrated that DDB2 can bind to the promoter region of NEDD4L and recruit enhancer of zeste homolog 2 histone methyltransferase to repress NEDD4L transcription by enhancing histone H3 lysine 27 trimethylation (H3K27me3) at the NEDD4L promoter. Given that NEDD4L plays an important role in constraining transforming growth factor β signaling by targeting activated Smad2/Smad3 for degradation, we investigated the role of DDB2 in the regulation of TGF-β signaling in ovarian cancer cells. Our data indicate that DDB2 enhances TGF-β signal transduction and increases the responsiveness of ovarian cancer cells to TGF-β-induced growth inhibition. The study has uncovered an unappreciated regulatory mode that hinges on the interaction between DDB2 and NEDD4L in human ovarian cancer cells. The novel mechanism proposes the DDB2-mediated fine-tuning of TGF-β signaling and its downstream effects that impinge upon tumor growth in ovarian cancers.

Nedd4-induced monoubiquitination of IRS-2 enhances IGF signalling and mitogenic activity

Insulin-like growth factors (IGFs) induce proliferation of various cell types and play important roles in somatic growth and cancer development. Phosphorylation of insulin receptor substrate (IRS)-1/2 by IGF-I receptor tyrosine kinase is essential for IGF action. Here we identify Nedd4 as an IRS-2 ubiquitin ligase. Nedd4 monoubiquitinates IRS-2, which promotes its association with Epsin1, a ubiquitin-binding protein. Nedd4 recruits IRS-2 to the membrane, probably through promoting Epsin1 binding, and enhances IGF-I receptor-induced IRS-2 tyrosine phosphorylation. In thyroid FRTL-5 cells, activation of the cyclic AMP pathway increases the association of Nedd4 with IRS-2, thereby enhancing IRS-2-mediated signalling and cell proliferation induced by IGF-I. The Nedd4 and IRS-2 association is also required for maximal activation of IGF-I signalling and cell proliferation in prostate cancer PC-3 cells. Nedd4 overexpression accelerates zebrafish embryonic growth through IRS-2 in vivo. We conclude that Nedd4-induced monoubiquitination of IRS-2 enhances IGF signalling and mitogenic activity.

NEDD4-2 (NEDD4L): the ubiquitin ligase for multiple membrane proteins

NEDD4-2 (also known as NEDD4L, neural precursor cell expressed developmentally down-regulated 4-like) is a ubiquitin protein ligase of the Nedd4 family which is known to bind and regulate a number of membrane proteins to aid in their internalization and turnover. Several of the NEDD4-2 substrates include ion channels, such as the epithelial and voltage-gated sodium channels. Given the critical function of NEDD4-2 in regulating membrane proteins, this ligase is essential for the maintenance of cellular homeostasis. In this article we review the biology and function of this important ubiquitin-protein ligase and discuss its pathophysiological significance.

Genome-wide analysis in human colorectal cancer cells reveals ischemia-mediated expression of motility genes via DNA hypomethylation

DNA hypomethylation is an important epigenetic modification found to occur in many different cancer types, leading to the upregulation of previously silenced genes and loss of genomic stability. We previously demonstrated that hypoxia and hypoglycaemia (ischemia), two common micro-environmental changes in solid tumours, decrease DNA methylation through the downregulation of DNMTs in human colorectal cancer cells. Here, we utilized a genome-wide cross-platform approach to identify genes hypomethylated and upregulated by ischemia. Following exposure to hypoxia or hypoglycaemia, methylated DNA from human colorectal cancer cells (HCT116) was immunoprecipitated and analysed with an Affymetrix promoter array. Additionally, RNA was isolated and analysed in parallel with an Affymetrix expression array. Ingenuity pathway analysis software revealed that a significant proportion of the genes hypomethylated and upregulated were involved in cellular movement, including PLAUR and CYR61. A Matrigel invasion assay revealed that indeed HCT116 cells grown in hypoxic or hypoglycaemic conditions have increased mobility capabilities. Confirmation of upregulated expression of cellular movement genes was performed with qPCR. The correlation between ischemia and metastasis is well established in cancer progression, but the molecular mechanisms responsible for this common observation have not been clearly identified. Our novel data suggests that hypoxia and hypoglycaemia may be driving changes in DNA methylation through downregulation of DNMTs. This is the first report to our knowledge that provides an explanation for the increased metastatic potential seen in ischemic cells; i.e. that ischemia could be driving DNA hypomethylation and increasing expression of cellular movement genes.

MicroRNAs cooperatively inhibit a network of tumor suppressor genes to promote pancreatic tumor growth and progression

BACKGROUND & AIMS

There has not been a broad analysis of the combined effects of altered activities of microRNAs (miRNAs) in pancreatic ductal adenocarcinoma (PDAC) cells, and it is unclear how these might affect tumor progression or patient outcomes.

METHODS

We combined data from miRNA and messenger RNA (mRNA) expression profiles and bioinformatic analyses to identify an miRNA-mRNA regulatory network in PDAC cell lines (PANC-1 and MIA PaCa-2) and in PDAC samples from patients. We used this information to identify miRNAs that contribute most to tumorigenesis.

RESULTS

We identified 3 miRNAs (MIR21, MIR23A, and MIR27A) that acted as cooperative repressors of a network of tumor suppressor genes that included PDCD4, BTG2, and NEDD4L. Inhibition of MIR21, MIR23A, and MIR27A had synergistic effects in reducing proliferation of PDAC cells in culture and growth of xenograft tumors in mice. The level of inhibition was greater than that of inhibition of MIR21 alone. In 91 PDAC samples from patients, high levels of a combination of MIR21, MIR23A, and MIR27A were associated with shorter survival times after surgical resection.

CONCLUSIONS

In an integrated data analysis, we identified functional miRNA-mRNA interactions that contribute to growth of PDACs. These findings indicate that miRNAs act together to promote tumor progression; therapeutic strategies might require inhibition of several miRNAs.

NEDD4L is downregulated in colorectal cancer and inhibits canonical WNT signaling

The NEDD4 family of E3 ubiquitin ligases includes nine members. Each is a modular protein, containing an N-terminal C2 domain for cell localization, two-to-four central WW domains for substrate recognition, and a C-terminal, catalytic HECT domain, which is responsible for catalyzing the ubiquitylation reaction. Members of this family are known to affect pathways central to the pathogenesis of colorectal cancer, including the WNT, TGFβ, EGFR, and p53 pathways. Recently, NEDD4 mRNA was reported to be overexpressed in colorectal cancer, but tumor stage was not considered in the analysis. Expression of the other family members has not been studied in colorectal cancer. Herein, we determined the expression patterns of all nine NEDD4 family members in 256 patients who presented with disease ranging from premalignant adenoma to stage IV colorectal cancer. NEDD4 mRNA was significantly increased in all stages of colorectal cancer. In contrast, NEDD4L mRNA, the closest homolog to NEDD4, was the most highly downregulated family member, and was significantly downregulated in all tumor stages. We also found NEDD4L protein was significantly decreased by western blotting in colorectal cancer samples compared to adjacent normal mucosa. In addition, NEDD4L, but not catalytically inactive NEDD4L, inhibited canonical WNT signaling at or below the level of β-catenin in vitro. These findings suggest that NEDD4L may play a tumor suppressive role in colorectal cancer, possibly through inhibition of canonical WNT signaling.

Pathobiological properties of the ubiquitin ligase Nedd4L in melanoma

A recent global gene expression profiling study unexpectedly showed that activated oncogenic NRAS may recruit neural precursor cell expressed, developmentally downregulated 4L (Nedd4L; a human homologue of Nedd4-2) in cultured melanoma cells. However, whether Nedd4L was expressed in melanoma tissues or participated in melanoma carcinogenesis remains to be clarified. Here, we investigated the expression status of Nedd4L in human melanocytes, benign nevi and melanoma tissue specimens and subsequently attempted to determine the role of Nedd4L in melanoma cell growth. Immunohistochemical staining revealed that Nedd4L was not present in any non-tumorous melanocytes or in 18 benign nevi tissues, but it was detected in 34 of 79 cutaneous melanomas and 9 of 32 nodal metastatic melanomas. Downregulation of Nedd4L significantly reduced the growth of cultured G361 melanoma cells in vitro. Moreover, exogenous Nedd4L expression significantly promoted the growth of A2058 melanoma cells in vivo in a xenograft assay. The present findings indicate that Nedd4L expression may be increased to facilitate tumour growth in many melanomas.

Identification of the NEDD4L gene as a prognostic marker by integrated microarray analysis of copy number and gene expression profiling in non-small cell lung cancer

PURPOSE

The purpose of this study was to identify prognostic genes by integrated microarray analysis between comparative genomic hybridization and gene expression with laser microdissection in non-small cell lung cancer (NSCLC).

METHODS

Integrated microarray analysis in 11 lung adenocarcinomas was performed, and several genes were identified. Among them, neural precursor cell-expressed developmentally down-regulated 4-like (NEDD4L) was chosen for further characterization. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was used to explore the clinicopathological significance of NEDD4L expression in 84 NSCLC patients.

RESULTS

18q was more frequently lost in advanced lung cancer. Therefore, we selected the NEDD4L gene, located on chromosome 18q, for which reduced expression was significantly correlated with copy number loss. NEDD4L mRNA expression in paired tumor/normal samples from 79 cases of lung cancer was evaluated using real-time PCR analysis. NEDD4L mRNA expression was significantly lower in tumor tissues than in normal lung tissues (p < 0.0001). Clinicopathological factors, such as excessive smoking history, histological grade (moderately and poorly), T stage (T2-4), lymph node metastasis, and pathological stage (stage II-IV), were significantly associated with low NEDD4L expression (p < 0.05). In the low expression group, prognoses were significantly poorer than in the high expression group (p < 0.05).

CONCLUSIONS

Low NEDD4L expression may be a marker of prognosis. This is the first report to describe NEDD4L expression in NSCLC. NEDD4L may be considered a key gene in the progression of NSCLC, and its expression is likely affected by genomic alterations.

Decreased expression of Nedd4L correlates with poor prognosis in gastric cancer patient

The neural precursor cell expressed, developmentally down-regulated 4-like (Nedd4L) gene encodes an ubiquitin ligase that targets the epithelial sodium channel for degradation. Recent studies have demonstrated that Nedd4L plays a role in the progression of various cancers. However, the clinical implications of Nedd4L expression status in gastric cancer have remained unclear. We examined the Nedd4L expression in 82 gastric cancer patients by immunohistochemistry. The correlation between Nedd4L expression and clinicopathological factors, including prognosis, was evaluated. Cancerous Nedd4L expression was detectable in 36 of the 82 tumors (43.9%). Tumors with negative Nedd4L expression had greater extent of lymph node metastasis, lymphatic invasion, and venous invasion, and were at a worse stage than the tumors with positive Nedd4L expression. Additionally, the patients with negative Nedd4L expression had poor clinical outcomes. Furthermore, multivariate analysis indicated that Nedd4L expression was an independent prognostic factor for gastric cancer patients. Our results suggest for the first time that negative Nedd4L expression is strongly related to the invasion and metastasis of gastric cancer. Therefore, Nedd4L expression can be used as an independent prognostic marker of gastric cancer.

Correlation between MMP1-PAR1 axis and clinical outcome of primary gallbladder carcinoma

OBJECTIVE

Matrix metalloprotease-1 and protease-activated receptor-1 axis plays an important role in many cancers, with activation often associated with poor survival. The aim of the present study was to determine whether the immunohistochemical detection of matrix metalloprotease-1 and protease-activated receptor-1 could provide useful information as novel therapeutic or prognostic factors in primary gallbladder carcinoma.

METHODS

Eighty-six gallbladder carcinoma tissues were evaluated by immunohistochemistry for matrix metalloprotease-1 and protease-activated receptor-1 expressions. The association of matrix metalloprotease-1 and protease-activated receptor-1 expressions with clinicopathological characteristics and the univariate survival analysis for the influence of matrix metalloprotease-1 and protease-activated receptor-1 expressions on the overall survival were analyzed.

RESULTS

Matrix metalloprotease-1 and protease-activated receptor-1 immunoreactivities were observed in 62 (72.1%) and 59 (68.6%) of the 86 gallbladder carcinoma cases, respectively. The tumors with the positive expressions of matrix metalloprotease-1 (P= 0.007) and protease-activated receptor-1 (P= 0.01) more frequently showed lymph node metastasis, respectively. In addition, the tumors with the positive expressions of matrix metalloprotease-1 and protease-activated receptor-1 tended to show a deeper invasion depth (P= 0.006 and 0.008, respectively) and more frequent lymphovascular invasion (both P= 0.01). The Kaplan-Meier survival curves demonstrated that patients with the positive expressions of matrix metalloprotease-1 and protease-activated receptor-1 had a significantly shorter survival time than those patients with their negative expression (both P= 0.02).

CONCLUSIONS

A subset of gallbladder carcinoma cases revealed the overexpression of matrix metalloprotease-1 and protease-activated receptor-1, which was associated with a progressive pathological feature and an aggressive clinical course. Therefore, matrix metalloprotease-1 and protease-activated receptor-1 expressions may be predictors for a poor prognosis in patients with gallbladder carcinoma. This is the first report describing about the involvement of matrix metalloprotease-1 and protease-activated receptor-1 axis in gallbladder carcinoma.

Matrix metalloproteinase-11 overexpressed in lobular carcinoma cells of the breast promotes anoikis resistance

The purpose of the present study was to examine the pathobiological properties of a matrix metalloproteinase, MMP-11 (also known as stromelysin-3), in the carcinogenesis of lobular carcinoma of the breast. Immunohistochemical staining demonstrated immunoreactivity with specific antibody to MMP-11 in 16 of 30 lobular carcinoma cells, but not in the non-cancerous terminal duct lobular unit. In positive cases, both noninvasive and invasive cancer cells exhibited immunoreactivity with anti-MMP-11 antibody; however, the staining patterns in noninvasive and invasive foci were distinct. In the noninvasive foci, immunoreactivity was observed in the cytoplasm beneath the plasma membrane, whereas immunoreactivity was found in all of the cytoplasm of infiltrating lobular carcinoma cells. Enforced expression of MMP-11 in the cultured lobular carcinoma MDA-MB-330 cells did not affect cell growth or Matrigel invasion activity. By contrast, overexpression of MMP-11 significantly increased resistance to anoikis, a programmed cell death triggered by a lack of proper cell matrix interaction, as evidenced by decrease in annexin V-positive cells and apoptotic DNA ladders. The present findings indicate that MMP-11 is overexpressed in many lobular carcinoma cells and that it may play a role in lobular carcinogenesis through increasing resistance to anoikis.