Epithelial-mesenchymal Transition In Nasopharyngeal Carcinoma Research Articles

Decreased BIRC5-206 promotes epithelial-mesenchymal transition in nasopharyngeal carcinoma through sponging miR-145-5p.

Metastasis significantly contributes to the poor prognosis of advanced nasopharyngeal carcinoma (NPC). Our prior studies have demonstrated a decrease in BIRC5-206 expression in NPC, which promotes disease progression. However, the role of BIRC5-206 in the invasion and metastasis of NPC has not been fully elucidated. In this study, our objective was to explore the biological function and underlying mechanisms of BIRC5-206 in NPC. Additionally, we established an NPC mouse model of lung invasiveness using C666 cells to assess the impact of BIRC5-206 on NPC metastasis. Our results revealed that silencing BIRC5-206 inhibited apoptosis and enhanced the invasion of NPC cells, whereas its overexpression reversed these effects. Moreover, decreased BIRC5-206 expression significantly increased N-cadherin and Vimentin expression while reducing E-cadherin and occludin levels, both in vivo and in vitro. Additionally, silencing BIRC5-206 markedly augmented the formation of invasive foci in lung tissues. Rescue experiments further confirmed that decreased BIRC5-206 expression facilitates NPC metastasis via modulation of the miR-145-5p/CD40 signaling pathway. In summary, our study suggests that BIRC5-206 may serve as a potential prognostic biomarker and therapeutic target in the diagnosis and treatment of NPC.

LncRNA FOXP4-AS1 silencing inhibits metastasis and epithelial-mesenchymal transition in nasopharyngeal carcinoma via miR-136-5p/MAPK1.

Nasopharyngeal carcinoma (NPC) is a malignant tumor caused by nasopharyngeal epithelium. Long non-coding RNAs (lncRNAs) and microRNAs have been identified as vital regulators in many tumors, including NPC. This study aimed to explain the biological roles and relevant mechanisms of lncRNA FOXP4-AS1 (FOXP4-AS1) in NPC. The levels of lncRNA FOXP4-AS1, miR-136-5p and MAPK1 in C666-1 and NP69 cells were analyzed by quantitative reverse transcription PCR (qRT-PCR). C666-1 cells viability, migration and invasion were evaluated by MTT and Transwell assay, respectively. The target gene of miR-136-5p predicted by TargetScan was further verified using dual luciferase reporter assay. Moreover, qRT-PCR and Western blot were adopted to assess epithelial-mesenchymal transition (EMT)-related gene expression, including E-cadherin and N-cadherin. We found that lncRNA FOXP4-AS1 was upregulated, while miR-136-5p was low-expressed in C666-1 cells, as opposed to NP69. Knockdown of FOXP4-AS1 notably suppressed C666-1 cell growth, inhibited cell migration and invasion. We also observed that E-cadherin expression was fortified and N-cadherin level was decreased in C666-1 cells after FOXP4-AS1-siRNA transfection. However, all these findings were eliminated in C666-1 cells after miR-136-5p inhibitor treatment. We also found miR-136-5p directly targeted MAPK1 and correlated inversely with MAPK1 expression in C666-1 cells. Further investigation suggested that MAPK1-plasmid reversed the effects of miR-136-5p mimic on cells viability, migration, invasion and EMT. To conclude, our data revealed that lncRNA FOXP4-AS1 knockdown alleviated metastasis and EMT in NPC via miR-136-5p/MAPK1, indicating that lncRNA FOXP4-AS1 may be a valuable therapeutic target for NPC diagnosis and treatment.

Effect of Shengmai Yin on Epithelial-Mesenchymal Transition of Nasopharyngeal Carcinoma Radioresistant Cells.

To investigate the mechanism by which Chinese medicine Shengmai Yin (SMY) reverses epithelial-mesenchymal transition (EMT) through lipocalin-2 (LCN2) in nasopharyngeal carcinoma (NPC) cells CNE-2R. Morphological changes in EMT in CNE-2R cells were observed under a microscope, and the expressions of EMT markers were detected using quantitative real-time PCR (RT-qPCR) and Western blot assays. Through the Gene Expression Omnibus dataset and text mining, LCN2 was found to be highly related to radiation resistance and EMT in NPC. The expressions of LCN2 and EMT markers following SMY treatment (50 and 100 µ g/mL) were detected by RT-qPCR and Western blot assays in vitro. Cell proliferation, migration, and invasion abilities were measured using colony formation, wound healing, and transwell invasion assays, respectively. The inhibitory effect of SMY in vivo was determined by observing a zebrafish xenograft model with a fluorescent label. The CNE-2R cells showed EMT transition and high expression of LCN2, and the use of SMY (5, 10 and 20 µ g/mL) reduced the expression of LCN2 and reversed the EMT in the CNE-2R cells. Compared to that of the CNE-2R group, the proliferation, migration, and invasion abilities of SMY high-concentration group were weakened (P<0.05). Moreover, SMY mediated tumor growth and metastasis in a dose-dependent manner in a zebrafish xenograft model, which was consistent with the in vitro results. SMY can reverse the EMT process of CNE-2R cells, which may be related to its inhibition of LCN2 expression. Therefore, LCN2 may be a potential diagnostic marker and therapeutic target in patients with NPC.

MACC1 Is Associated With Epithelial-Mesenchymal Transition and Can Predict Poor Prognosis in Nasopharyngeal Carcinoma.

BackgroundGiven the reported correlation between the oncogene metastasis-associated in colon cancer 1 (MACC1) and nasopharyngeal carcinoma (NPC), as well as between MACC1 and epithelial–mesenchymal transition (EMT), we speculated that EMT is a likely causative link between MACC1 expression and poor NPC prognosis. Thus, we aim to clarify the relationship between MACC1 and EMT in NPC prognosis.Material and MethodsWe performed immunohistochemical examination of tissue sections from 128 NPC patients that were divided into six groups corresponding to high and low protein expression of MACC1 and two EMT-related proteins, vimentin and E-cadherin, and Kaplan–Meier (KM) survival analyses were performed.ResultsKM survival analysis showed that upregulation of MACC1 and vimentin and downregulation of E-cadherin were significantly associated with reduced survival in NPC. Short hairpin RNA (shRNA) interference and immunoblotting in the NPC cell line HNE-1 led to increased E-cadherin but decreased vimentin levels. MACC1 overexpression was significantly correlated with poor 5-year overall survival, metastasis-free survival, and disease-free survival (P<0.05) but not with poor relapse-free survival (P>0.05). Univariate analyses revealed that MACC1, E-cadherin, and vimentin levels along with T and N tumor classifications and cancer staging are significant prognostic factors of NPC (P<0.05).ConclusionOur findings showed the association between MACC1 and EMT in NPC malignancy and support the role of MACC1 as a prognostic biomarker and molecular target for NPC treatment.

Silencing of Long Non-coding RNA SMAD5-AS1 Reverses Epithelial Mesenchymal Transition in Nasopharyngeal Carcinoma via microRNA-195-Dependent Inhibition of SMAD5.

Long non-coding RNAs (lncRNAs) have gained widespread attention in recent years as a key regulator of diverse biological processes, but the knowledge of the mechanisms by which they act is still very limited. Differentially expressed lncRNA SMAD5 antisense RNA 1 (SMAD5-AS1) in nasopharyngeal carcinoma (NPC) and normal samples shown by in silico analyses were selected as the main subject, and then microRNA-195 (miR-195) was suggested to bind to SMAD5-AS1 and SMAD5. Therefore, the purpose of the present study was to investigate the effects of SMAD5-AS1/miR-195/SMAD5 on epithelial-mesenchymal transition (EMT) in NPC cells. High expression of SMAD5-AS1 and SMAD5 but low miR-195 expression was determined in NPC tissues and NPC cell lines by RT-qPCR and western blot analysis. SMAD5-AS1 could upregulate SMAD5 expression by competitively binding to miR-195 in NPC cells. Loss- and gain-of-function investigations were subsequently conducted in NPC cells (CNE-2 and CNE-1) to explore the role of SMAD5-AS, miR-195 and SMAD5 in NPC progression by assessing cellular biological functions and tumorigenic ability in vivo as well as determining the expression of EMT markers. Downregulation of SMAD5-AS1 or SMAD5 or overexpression of miR-195 led to inhibited NPC cell proliferation, invasion and migration and reversed EMT, enhanced apoptosis in vitro as well as restrained tumor growth in vivo. In conclusion, our findings indicate that silencing of lncRNA SMAD5-AS1 induces the downregulation of SMAD5 by miR-195, eventually repressing EMT in NPC. Hence, SMAD5-AS1 may represent a potential therapeutic target for NPC intervention.

Matrix metalloproteinase 2 contributes to aggressive phenotype, epithelial-mesenchymal transition and poor outcome in nasopharyngeal carcinoma.

BackgroundThough matrix metalloproteinase 2 (MMP-2) involvement in tumor aggressiveness and invasion is well-known, its prognostic impacts still remain largely controversial. Furthermore, the correlations between MMP-2 and epithelial-mesenchymal transition (EMT) have not been directly established in nasopharyngeal carcinoma (NPC).Materials and methodsThe purpose of this study was to investigate MMP-2 expression in NPC. Tissue microarrays from 144 patients with NPC and 45 non-cancerous pharynx tissues were analyzed for MMP-2 expression by immunohistochemistry. MMP-2 expression in relation to clinicopathological characteristics and EMT were assessed in NPC. Tumor-invasive potential affected by exogenous expression of MMP-2 in NPC cells was also detected in vitro.ResultsCompared to normal nasopharyngeal epithelium, high expression of tumoral MMP-2 was detected in 47.9% of NPC samples. Significant association was found between MMP-2 expression and various aggressive features including T classification, M classification and tumor stage (P<0.05). Of note, high expression of MMP-2 was prominently observed at tumor invasive front, neoplastic spindle cells migrating into the stroma and vessel invasion. Importantly, high MMP-2 expression predicted worse survival in patients with stage III–IV (P=0.039). Overexpression of MMP-2 could decrease cell-cell adhesion, promote tumor invasion and EMT including downregulation of E-cadherin and upregulation of N-cadherin, Fibronectin and Slug of NPC cells.ConclusionOur findings demonstrate that MMP-2 expression contributes to tumor aggressiveness and poor prognosis, and induces the occurrence of EMT in NPC.

MiR-144-3p facilitates nasopharyngeal carcinoma via crosstalk with PTEN.

This study aims to investigate the role of miR-144-3p and phosphatase and tensin homolog (PTEN) in nasopharyngeal carcinoma (NPC), along with their crosstalk with the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) pathway. Quantitative reverse transcription polymerase chain reaction and western blot were used to measure the gene expression at the transcriptional and translational levels. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and colony formation assay were used to examine cell proliferation via standard protocol. Transwell assay was conducted to examine cell invasiveness. A flow cytometer was used to determine cell apoptosis. Dual-Luciferase Reporter Gene Assay (SLDL-100) was used to confirm the target relationship between miR-144-3p and PTEN. Xenografts were used to detect the in vivo effects of the molecules of interest. miR-144-3p was significantly overexpressed, whereas PTEN was more underexpressed in tumor tissues than in adjacent tissues. miR-144-3p promoted the proliferation and invasion of NPC cells and inhibited apoptosis by directly targeting PTEN, which improves PI3K-Akt signaling. miR-144-3p forced epithelial-mesenchymal transition in NPC. miR-144-3p promotes the progression of NPC by directly targeting PTEN via crosstalk with PI3K-Akt signaling.

Placenta specific 8 gene induces epithelial-mesenchymal transition of nasopharyngeal carcinoma cells via the TGF-β/Smad pathway

The present study aimed to investigate the effects and mechanisms of PLAC8 on the epithelial-mesenchymal transition (EMT) of Nasopharyngeal carcinoma (NPC). The expression of PLAC8 in NPC and nasopharyngitis (NPG) tissues from 150 patients was determined using immunohistochemistry. The levels of PLAC8 in five NPC cell lines and nasopharyngeal permanent epithelial cell line were measured using western blotting. We then knocked out or overexpressed PLAC8 in CNE2 cells. Cell proliferation, wound healing, migration, and invasion assays were used to analyze the effects of PLAC8 on the proliferation, migration, and invasion in vivo and vitro. The results showed that the expression of PLAC8 was much higher in NPC tissues than in NPG tissues. The expression of PLAC8 was higher in all the cell lines than in the nasopharyngeal permanent epithelial cells. PLAC8 knockout resulted in significant decreases in cell proliferation, migration, and invasion; associated with lower protein levels of N-cadherin; and increased levels of E-cadherin. Overexpression of PLAC8 had the opposite effect. Furthermore, knockout of PLAC8 inactivated TGF-β/SMAD signaling pathway and suppressed the growth of NPC xenografts. PLAC8 may promote the carcinogenesis and EMT of NPC via the TGF-β/Smad pathway, which suggests that PLAC8 may be a potential biomarker for NPC.

MiRNA-34a reversed TGF-β-induced epithelial-mesenchymal transition via suppression of SMAD4 in NPC cells

Epithelial–mesenchymal transition (EMT) is considered a prerequisite for tumor invasion and metastasis in many cancers. However, the mechanisms underlying EMT in nasopharyngeal carcinoma (NPC) is largely unknown. In this study, we found that transforming growth factor-β (TGF-β), which reportedly promotes EMT in multiple cancers, can trigger EMT and increase the invasive and migratory capacities of NPC cells. Conversely, the downregulation of SMAD4, a vital member of the canonical TGF-β pathway, reversed the TGF-β-induced EMT, invasion, and migration. Further experiments revealed that SMAD4 was the target of miRNA-34a, which was downregulated in NPC tissues and suppressed NPC cell metastasis in vivo. miRNA-34a overexpression also antagonized the TGF-β-induced EMT progression, invasion, and migration through SMAD4 inhibition. However, the restoration of SMAD4 expression rescued the inhibitory effects of miRNA-34a on tumorigenesis. All these results confirmed that miRNA-34a suppressed the TGF-β-induced EMT, invasion, and migration of NPC cells by directly targeting SMAD4, which indicated the potential of miR-34a as a therapeutic target against NPC.

Positive regulation of TAZ expression by EBV-LMP1 contributes to cell proliferation and epithelial-mesenchymal transition in nasopharyngeal carcinoma.

The Epstein-Barr virus latent membrane protein 1 (LMP1) is an integral membrane protein. LMP1 has been reported to activate the NF-κB and mitogen-activated protein kinase pathways. However, these effects alone are unable to account for the profound oncogenic properties of LMP1. TAZ is one of the nuclear effectors of Hippo-related pathways and highly expressed in many human tumors. Here, we reported that TAZ was frequently expressed in LMP1-positive nasopharyngeal carcinoma. In NPC cell lines, we showed that LMP1 promoted TAZ expression. Gelsolin is an important inhibitor of TAZ activity. Our studies showed that LMP1 interacted with gelsolin, resulting in inhibition of Lats1/2 phosphorylation and improvement of TAZ stability. Furthermore, we revealed that TAZ is important for LMP1-mediated cell proliferation, cancer stem cell-like properties and epithelial-mesenchymal transition. These findings provide new insights into the carcinogenic roles of LMP1 and contribute to further understanding of its oncogenic mechanism.

ZNF488 Enhances the Invasion and Tumorigenesis in Nasopharyngeal Carcinoma Via the Wnt Signaling Pathway Involving Epithelial Mesenchymal Transition.

PurposeThe purpose of this study was to investigate the function of Zinc finger protein 488 (ZNF488) in nasopharyngeal carcinoma (NPC).Materials and MethodsThe endogenous expression of ZNF488 in NPC tissues, normal nasopharyngeal epithelium tissues and NPC cell lines were detected by quantitative reverse transcription polymerase chain reaction. ZNF488 over-expressing and knock-down NPC cell line models were established through retroviral vector pMSCV mediated over-expression and small interfering RNA (siRNA) mediated knock-down. The invasion and migration capacities were evaluated by wound healing and transwell invasion assays in ZNF488 over-expressing and control cell lines. Soft-agar colony formation and a xenograft experiment were performed to study tumorigenic ability in vitro and in vivo. Immunofluorescence and western blotting analysis were used to examine protein changes followed by ZNF488 over-expression. Microarray analysis was performed to explore gene expression profilings, while luciferase reporter assay to evaluate the transcriptive activity of Tcf/Lef.ResultsZNF488 was over-expressed in NPC tissues compared with normal tissues, especially higher in 5-8F and S18, which are well-established high metastatic NPC clones. Functional studies indicate that over-expression of ZNF488 provokes invasion, whereas knock-down of ZNF488 alleviates invasive capability. Moreover, over-expression of ZNF488 promotes NPC tumor growth both in vitro and in vivo. Our data further show that over-expression of ZNF488 induces epithelial mesenchymal transition (EMT) by activating the WNT/β-catenin signaling pathway.ConclusionOur data strongly suggest that ZNF488 acts as an oncogene, promoting invasion and tumorigenesis by activating the Wnt/β-catenin pathway to induce EMT in NPC.

Abstract 1150: The role of the tumor suppressor gene THY1 in suppression of epithelial-mesenchymal transition (EMT) in nasopharyngeal carcinoma

Abstract Background and aims: THY1 has been successfully identified as a tumor suppressor gene (TSG) in nasopharyngeal carcinoma (NPC) in our laboratory. The frequency of down-regulated THY1 protein expression was found to be significantly associated with NPC lymph node metastases. However, direct functional evidence is still lacking for THY1 being anti-metastatic in NPC. Epithelial-Mesenchymal Transition (EMT) is well-known as a closely associated process for stem cells as well as tumor cells to invade to other part of the body. We aim to study the association of EMT with the THY1 in NPC. Methods: Functional analysis of restoration of THY1 expression in the NPC cell lines was studied. The RhoA negative regulator, p190 Rho GTPase-activating protein (p190RhoGAP) and the E-cadherin/beta-catenin cell junction was examined in the THY1-expressing NPC cells. Results: Both real-time and conventional invasion chamber assays clearly showed that the invasive ability of the THY1 transfectants was consistently lower than vector-alone control. The reverse transcription-polymerase chain reaction (RT-PCR) results show that the gene expression of cell invasion-associated gelatinase MMP-9 was significantly down-regulated in the THY1-transfectants compared with the vector-alone control. The p190RhoGAP was greatly activated by phosphorylation in the THY1 transfectants, when the THY1 gene was switched on in the absence of doxycycline (dox, an analogue of tetracycline). In the presence of dox when THY1 was switched off, the phosphorylation of p190RhoGAP was reduced. It appears that the phosphorylation status of p190RhoGAP is positively regulated by THY1 in NPC cells. The immunofluorescence (IF) confocal microscopy results show that beta-catenin and E-cadherin were much more frequently translocated to the cell-cell junction in the THY1 transfectants than the vector-alone. Conclusions: These findings suggest that THY1 inhibited NPC cell invasion via the formation of adherens junction and up-regulation of p190RhoGAP. The enhanced formation of cell adherens junction by THY1 is likely to be one of the possible mechanisms to suppress EMT in NPC. Citation Format: Hong Lok Lung, Maria Li Lung. The role of the tumor suppressor gene THY1 in suppression of epithelial-mesenchymal transition (EMT) in nasopharyngeal carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1150. doi:10.1158/1538-7445.AM2014-1150

Epstein-Barr virus-encoded latent membrane protein 2A promotes the epithelial-mesenchymal transition in nasopharyngeal carcinoma via metastatic tumor antigen 1 and mechanistic target of rapamycin signaling induction.

Epstein-Barr virus-encoded latent membrane protein 2A (LMP2A) promotes the epithelial-mesenchymal transition (EMT) of nasopharyngeal carcinoma (NPC), thereby increasing tumor invasion. Recently, the dysregulation of metastatic tumor antigen 1 (MTA1) was found to enhance tumor metastasis in a variety of cancers. A molecular connection between these two proteins has been proposed but not firmly established. In this study, we reported the overexpression of MTA1 in 29/60 (48.3%) NPC patients, and the overexpression of MTA1 significantly correlated with tumor metastasis. The overexpression of MTA1 promoted EMT via the Wnt1 pathway and β-catenin activation. We demonstrated that LMP2A reinforces the expression of MTA1 via the mechanistic target of rapamycin (mTOR) pathway to promote EMT in NPC. Furthermore, by knocking down 4EBP1 in combination with the new mTOR inhibitor INK-128 treatment, we discovered that LMP2A expression activates the 4EBP1-eIF4E axis and increases the expression of MTA1 at the translational level partially independent of c-myc. These findings provided novel insights into the correlation between the LMP2A and MTA1 proteins and reveal a novel function of the 4EBP1-eIF4E axis in EMT of nasopharyngeal carcinoma. Importance: Prevention of the recurrence and metastasis of NPC is critical to achieving a successful NPC treatment. As we all know, EMT has a vital role in metastasis of malignancies. LMP2A, an oncoprotein of Epstein-Barr virus, a well-known NPC activator, induces EMT and has been proved to exert a promoting effect in tumor metastasis. Our study demonstrated that LMP2A could induce EMT by activating MTA1 at the translational level via activating mTOR signaling and the 4EBP1-eIF4E axis. Taken together, our findings bridge the gap between the NPC-specific cell surface molecule and the final phenotype of the NPC cells. Additionally, our findings indicate that LMP2A and mTOR will serve as targets for NPC therapy in the future.

Epstein–Barr virus latent membrane protein-2A alters mitochondrial dynamics promoting cellular migration mediated by Notch signaling pathway

Recently, migration and invasion of breast cancer cells have been linked with dysregulated mitochondrial dynamics. Mitochondria are essential cellular organelles that undergo continuous dynamic cycles of fission and fusion. It has been proposed that a delicate balance between these two processes is important for many pathophysiological outcomes including cancer. Epstein-Barr virus (EBV) is a gamma herpesvirus that is associated with various lymphoid and epithelial malignancies. The viral latent membrane protein 2A (LMP2A) has been shown to increase the invasive ability and induce epithelial-mesenchymal transition in nasopharyngeal carcinoma. Our present study reveals that mitochondrial dynamics also plays a critical role in Epstein-Barr virus-associated epithelial cancers. Our data indicate that viral LMP2A causes an elevated mitochondrial fission in gastric and breast cancer cells, which is manifested by elevated fission protein dynamin-related protein 1 (Drp1). Furthermore, LMP2A-mediated Notch pathway is responsible for this enhanced fission since inhibitors of the pathway decrease the expression of Drp1.

Correction: Embryonic Stem Cells Markers SOX2, OCT4 and Nanog Expression and Their Correlations with Epithelial-Mesenchymal Transition in Nasopharyngeal Carcinoma

Correction: Embryonic Stem Cells Markers SOX2, OCT4 and Nanog Expression and Their Correlations with Epithelial-Mesenchymal Transition in Nasopharyngeal Carcinoma

Embryonic Stem Cells Markers SOX2, OCT4 and Nanog Expression and Their Correlations with Epithelial-Mesenchymal Transition in Nasopharyngeal Carcinoma

Expression of embryonic stem cells (ESCs) markers (SOX2, OCT4, Nanog and Nestin) is crucial for progression of various human malignancies. The purpose of this study was to investigate the expression and prognostic impact of these molecules in nasopharyngeal carcinoma (NPC) patients by immunohistochemistry and immunofluorescence. In the present study, we found that the expression levels of SOX2, OCT4 and Nanog were highly expressed in NPC compared with the non-tumorous tissues. Furthermore, these proteins correlated significantly with several clinicalpathological factors and epithelial-mesenchymal transition (EMT)-associated indicators (E-cadherin/N-cadherin and Snail). In multivariate analyses, high expression of OCT4 (P = 0.013) and Nanog (P = 0.040), but not that of SOX2, was associated with worse survival and had strongly independent prognostic effects. Of note, OCT4 and Nanog were more frequently located at the invasive front of tumors, and correlated significantly with various aggressive behaviors including T classification, N classification, M classification and clinical stage. Furthermore, patients with co-expression of OCT4 and Nanog in the invasive front had significantly worse survival (P = 0.005). Interestingly, at the invasive front, these molecules correlated significantly with Nestin expression in endothelial cells (P<0.001). These findings provide evidence that ESCs biomarkers OCT4 and Nanog serves as independent prognostic factors for NPC. Additionally, cancer cells in the invasive front of NPC acquiring ESCs-like features should be maintained by vascular niches.

Epstein-Barr Virus latent membrane protein 1 induces Snail and epithelial–mesenchymal transition in metastatic nasopharyngeal carcinoma

Background:Epstein-Barr Virus (EBV)-associated nasopharyngeal carcinoma (NPC) is distinctive among head-and-neck cancers in its undifferentiated histopathology and highly metastatic character. We have recently investigated the involvement of epithelial–mesenchymal transition (EMT) in NPC. In a previous study, we found a close association of expression of LMP1, the principal EBV oncoprotein, with expression of Twist and induction of EMT.Methods:We analysed expression of Snail in 41 NPC tissues by immunohistochemistry. The role of Twist as well as Snail in EMT of NPC was investigated by using NP69SV40T human nasopharyngeal cells.Results:In NPC tissues, overexpression of Snail is associated with expression of LMP1 in carcinomatous cells. In addition, expression of Snail positively correlated with metastasis and independently correlated inversely with expression of E-cadherin. Expression of Twist had no association with expression of E-cadherin. Further, in a human nasopharyngeal cell line, LMP1 induces EMT and its associated cellular motility and invasiveness. Expression of Snail is induced by LMP1 in these cells, and small hairpin RNA (shRNA) to Snail reversed the cellular changes. By contrast, Twist did not produce EMT in these nasopharyngeal cells.Conclusions:This study strengthens the association of EMT with the metastatic behaviour of NPC. These results suggest that induction of Snail by the EBV oncoprotein LMP1 has a pivotal role in EMT in NPC.