Nasopharyngeal Carcinoma Cell Epithelial-mesenchymal Transition Research Articles

MiR-137 Regulates Proliferation, Migration, Invasion and EMT of Nasopharyngeal Carcinoma Cells by Targeting TWIST1

To investigate the effects of miR-137 on biological cell function of nasopharyngeal carcinoma (NPC) cells. Totally, 31 pairs of NPC tissues and para-cancer tissues were collected. Meanwhile, human immortalized nasopharyngeal epithelial cell lines (NP69) and human NPC cell lines (6-10B) were cultured. The abilities of cell proliferation, invasion and migration were detected by CCK-8 and Transwell assay, respectively. The relative protein and mRNA expression level was detected by Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. In quantitative real-time polymerase chain reaction (qRT-PCR) experiment, miR-137 was found widely low-expressed in clinical samples and cell lines of nasopharyngeal carcinoma (NPC). On-line target gene prediction software was applied to screen potential downstream target of miR-137 in NPC. Then, Twist Family BHLH Transcription Factor 1 (TWIST1) was verified by luciferase reporter assay and Western blot experiments as a target for negative regulation of miR-137 in NPC cells. We up-regulated the expression of miR-137 and/or TWIST1 in 6-10Bin vitro, and then examined the effects of cell function after by CCK8, Transwell, scratch-wound and Western blot experiments. The results showed that decreased expression of TWIST1 resulting from up-regulation of miR-137 in 6-10B cells could inhibit the biological functions of cells including proliferation, invasion, migration and process of epithelial-mesenchymal transition (EMT). Our research discovered the suppressor function of miR-137 on NPC cells by targeting TWIST1, suggesting that miR-137 could be used as a potential therapeutic target for NPC.

MiR-339-3p inhibits cell growth and epithelial-mesenchymal transition in nasopharyngeal carcinoma by modulating the KAT6A/TRIM24 axis.

To explore the effect and mechanism of the miR-339-3p/KAT6A/TRIM24 axis in nasopharyngeal carcinoma (NPC) cell growth and epithelial-mesenchymal transition (EMT) progression. CNE2 and 5-8F NPC cell lines were transfected with miR-339-3p-mimic or sh-KAT6A alone or co-transfected with miR-339-3p-mimic and oe-KAT6A. The expression levels of miR-339-3p, KAT6A, TRIM24, and EMT-related proteins were assessed, in addition to cell biological behaviors. Then, the relationship between miR-339-3p and KAT6A was predicted and validated. The correlations between miR-339-3p and KAT6A or between KAT6A and TRIM24 were analyzed by Pearson coefficient and the enrichment of H3K23ac in TRIM24 promoter region was measured by chromatin immunoprecipitation. miR-339-3p was downregulated, but KAT6A and TRIM24 were highly expressed in NPC cells and tissues. Upregulated miR-339-3p or downregulated KAT6A could inhibit the growth and EMT of NPC cells. Further experiments showed that miR-339-3p regulated NPC cell growth and EMT by mediating KAT6A in a targeted fashion. KAT6A was positively correlated with TRIM24, and the enrichment of H3K23ac was much higher in NPC tissues. miR-339-3p suppressed the growth and EMT of NPC cells by the KAT6A/TRIM24 axis. In a xenograft study, miR-339-3p overexpression inhibited NPC tumor growth in vivo. Conclusively, miR-339-3p inhibited the growth and EMT of NPC cells via the KAT6A/TRIM24 axis.

Expression and Biological Functions of EPC1 in Nasopharyngeal Carcinoma.

Comb homolog enhancer 1 (EPC1) gene is one of the important members of epigenetic inhibitor PCG family. It shows carcinogenic potential in a variety of malignant tumors, but the expression and role of EPC1 in nasopharyngeal carcinoma are unclear. The aim of this study was to explore the expression and function of enhancer of polycomb homolog 1 (EPC1) in nasopharyngeal carcinoma (NPC). The differential expression of EPC1 in the cancer tissues and cell lines of NPC was examined by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). EPC1 expression, cell proliferation, and apoptosis were detected in NPC cell lines after EPC1 silencing, and the levels of the epithelial-mesenchymal transition (EMT)-related proteins E-cadherin and vimentin were detected in NPC cells after EPC1 silencing. The study was performed at Fujian Provincial Hospital, Fujian, China, from 2018 to 2019. We found that EPC1 was significantly upregulated in the cancer tissues and cell lines of NPC (P<0.001). Furthermore, knockdown of EPC1 inhibited the growth and metastasis of NPC cells. E-cadherin and vimentin were detected in NPC cells after EPC1 was knocked out. It was confirmed that inhibition of EPC1 resulted in increased E-cadherin expression (P<0.001) and decreased vimentin expression (P<0.001), suggesting that inhibition of EPC1 could inhibit the EMT in NPC cells. EPC1 expression was upregulated in NPC tissues and cell lines. Knockout of EPC1 effectively inhibited the growth of NPC cells, induced apoptosis, and inhibited invasion and metastasis. Inhibition of EPC1 could inhibit the EMT in NPC cells. All of the above findings support the viewpoint that EPC1 plays a pro-cancer role in NPC.

Lnc-MEG3 inhibits invasion, migration, and epithelial- mesenchymal transition of nasopharyngeal carcinoma cells by regulating sequestosome 1.

Long non-coding RNAs regulate malignant behaviors of nasopharyngeal carcinoma (NPC). We aim to investigate the roles and mechanisms of long non-coding RNA maternally expressed gene 3 (lnc-MEG3) in NPC. The expression levels of lnc-MEG3 and sequestosome 1 (SQSTM1) in NPC tissues and cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell invasion and migration abilities were evaluated using transwell and wound healing assays, respectively. Downregulated lnc-MEG3 expression and upregulated SQSTM1 expression were found in NPC tissues and cells. Overexpression of lnc-MEG3 inhibited invasion, migration, and epithelial-mesenchymal transition in NPC cells. Overexpression of lnc-MEG3 reduced the expression level of SQSTM1, and SQSTM1 expression was inversely correlated with lnc-MEG3 level in NPC tissues. Besides, overexpression of SQSTM1 reversed the effects of lnc-MEG3 overexpression. Moreover, knockdown of lnc-MEG3 enhanced NPC progression while its effects were eased by SQSTM1 silence. Lnc-MEG3 inhibits malignant behaviors by regulating SQSTM1 expression. It may serve as a therapeutic target to treat NPC.

Limb-bud and heart (LBH) inhibits cellular migration, invasion and epithelial-mesenchymal transition in nasopharyngeal carcinoma via downregulating αB-crystallin expression

Limb-bud and heart (LBH) gene has received increasing attention in recent cancer studies. Here we investigated the role of the LBH gene in regulating the metastasis capacity and epithelial-mesenchymal transition (EMT) of nasopharyngeal carcinoma (NPC) cells, and its potential mechanism. The expressions of LBH and αB-crystallin (CRYAB) were modulated by lentiviral infection, or plasmid/siRNA transfection, and the phosphorylation of p38 was suppressed by an inhibitor, to explore their functions in modulating NPC cell phenotypes, as well as the relationships of these factors with each other. Cellular proliferation, migration and invasion were examined by RTCA system, Transwell assays and Matrigel Transwell assays respectively. The EMT progression was indicated by RT-qPCR and Western blotting measuring the expressions of EMT biomarkers. NPC xenografts were constrcucted, and formed tumors were sectioned for morphology and immunohistofluorescence. The interaction between LBH and CRYAB was examined by colocalization and Fluorescence resonance energy transfer (FRET) analysis. We reached the conclusion that LBH inhibits the proliferation, migration, invasion and EMT of NPC cells, and its effects were partially achieved by suppressing p38 phosphorylation, which subsequently downregulates the mRNA expression and phosphorylation of CRYAB, while CRYAB directly interacts with LBH in NPC cells. This LBH-related pathway we revealed provides a novel therapeutic target for nasopharyngeal carcinoma research.

Effects of baohuoside-I on epithelial-mesenchymal transition and metastasis in nasopharyngeal carcinoma.

To investigate the effect of baohuoside-I against nasopharyngeal carcinoma (NPC) and its underlying mechanism, baohuoside-I was employed to treat NPC cell lines CNE1 and CNE2 in vitro, followed by attachment and detachment assays to evalute the epithelial-mesenchymal transition (EMT) phenotype markers. Baohuoside-I was also administered to experimental mice to assess its effect on xenograft tumor growth and NPC cell metastasis. A microRNA (miRNA, miR) microarray was performed to screen for miRNA altered by baohuoside-I in NPC cells. Bioinformatic tools and luciferase activity assay was conducted to identify the downstream molecules mediating the anti-tumor property of baohuoside-I. Baohuoside-I inhibited EMT and metastasis and upregulated miR-370-3p in NPC cells, which was shown to directly recognize and inhibit expression of Hedgehog pathway component Smoothened (SMO). Baohuoside-I suppresses metastasis as well as EMT of NPC cells through targeting the Hedgehog pathway component SMO, and may serve as a potent anti-tumor agent in the clinical management of NPC.

LncRNA AATBC regulates Pinin to promote metastasis in nasopharyngeal carcinoma.

Long noncoding RNA (lncRNA) have emerged as crucial regulators for a myriad of biological processes, and perturbations in their cellular expression levels have often been associated with cancer pathogenesis. In this study, we identified AATBC (apoptosis‐associated transcript in bladder cancer, LOC284837) as a novel lncRNA. AATBC was found to be highly expressed in nasopharyngeal carcinoma (NPC), and increased AATBC expression was associated with poor survival in patients with NPC. Furthermore, AATBC promoted migration and invasion of NPC cells in vitro, as well as metastasis in vivo. AATBC upregulated the expression of the desmosome‐associated protein pinin (PNN) through miR‐1237‐3p sponging. In turn, PNN interacted with the epithelial–mesenchymal transition (EMT) activator ZEB1 and upregulated ZEB1 expression to promote EMT in NPC cells. Collectively, our results indicate that AATBC promotes NPC progression through the miR‐1237‐3p–PNN–ZEB1 axis. Our findings indicate AATBC as a potential prognostic biomarker or therapeutic target in NPC.

MicroRNA-379-5p/YBX1 Axis Regulates Cellular EMT to Suppress Migration and Invasion of Nasopharyngeal Carcinoma Cells.

BackgroundEpithelial–mesenchymal transition (EMT) is a major actor modulating the metastasis of nasopharyngeal carcinoma (NPC). Increasing evidence indicates that microRNAs (miRs) are the important regulators of EMT program. However, the potential roles and underlying mechanisms of miR‑379-5p in regulating EMT of NPC cells remain unclear.MethodsmiR-379-5p expression levels in human NPC tissues and cell lines were detected via quantitative real-time PCR (qRT-PCR). Then, the correlations between miR-379-5p expression in NPC tissues and clinicopathologic features and patients’ prognosis were analyzed. The effect of miR-379-5p on the expression of EMT markers in NPC cells was evaluated by Western blot and qRT-PCR. NPC cells’ migration and invasion were evaluated in vitro by Transwell migration and invasion assays, respectively. The target of miR-379-5p was predicted with three publicly available databases and further validated with dual-luciferase reporter assay, qRT-PCR, and Western blot.ResultsThe expression of miR-379-5p was significantly decreased in NPC tissues, and its low expression was significantly associated with multiple unfavorable clinicopathological factors and poor prognosis of NPC patients. Meanwhile, miR-379-5p was downregulated in NPC cell lines, and its exotic expression inhibited EMT to reduce the migration and invasion of NPC cells. Furthermore, Y-box binding protein 1 (YBX1) was identified and validated as a direct target of miR-379-5p, and restoring YBX1 expression could reverse the inhibitive effect of miR-379-5p on NPC cell EMT, migration and invasion.ConclusionTaken together, our findings indicate that miR-379-5p inhibits the EMT of NPC cells to reduce their migration and invasion abilities by post-transcriptionally suppressing YBX1 expression, providing a novel potential treatment target for NPC patients.

EB virus promotes metastatic potential by boosting STIM1-dependent Ca2+ signaling in nasopharyngeal carcinoma cells.

Nasopharyngeal carcinoma (NPC) is a unique head and neck malignancy with highly metastatic cell-biological characteristics, for which latent EBV-infection is responsible. Our earlier studies showed that EGF-stimulated Ca2+ signaling via store-operated Ca2+ entry (SOCE) was amplified in NPC cells expressing EBV-encoded LMP1, thus contributing to EBV-enhanced metastatic capacities. However, the pathway through which EBV modulates cytosolic Ca2+ signaling still remains unclear. Here, we demonstrated that EBV-infection amplified EGF-stimulated Ca2+ responses through the promotion of intracellular aggregation of STIM1, which serves as a Ca2+ sensor to activate SOCE. Blockage of EBV-remodeled Ca2+ signaling by STIM1-silencing inhibited cell migration by interrupting epithelial-mesenchymal transition (EMT) in vitro, and suppressed tumor dissemination in zebrafish and lymph node metastasis in mice. In addition, STIM1 expression was upregulated in primary NPC tissues compared with normal nasopharyngeal epithelium and stronger among the patients with advanced lymph node metastatic disease (N2-3 stage). Our findings thus indicate that EBV promotes metastatic potential by enhancing STIM1-dependent Ca2+ signaling that manipulates EMT in NPC cells. EBV-modulated Ca2+ signaling could serve as a candidate anti-metastatic target for NPC treatment.

LncRNA XIST knockdown suppresses the malignancy of human nasopharyngeal carcinoma through XIST/miRNA-148a-3p/ADAM17 pathway in vitro and in vivo

BackgroundLong non-coding RNA (lncRNA) X inactivate-specific transcript (XIST) has been verified as an oncogenic gene in human cancers, including nasopharyngeal carcinoma (NPC). However, the role of XIST in NPC remains to be largely uncovered, as well as its underlying mechanism. MethodsExpression of XIST, miR-148a-3p and ADAM17 was detected using qPCR and western blot assay. Cell proliferation and apoptosis assay were measured with MTT and flow cytometry, separately. Migration and invasion abilities were examined by transwell assays. Epithelial-mesenchymal transition (EMT) was assessed by western blot analyzing levels of E-cadherin, N-cadherin and vimentin. The potential binding between miR-148a-3p and XIST/ADAM17 was validated by luciferase reporter assay, Ago2-RNA immunoprecipitation and RNA pull-down assay. Xenograft experiments were conducted to measure tumor growth. ResultsXIST was upregulated and miR-148a-3p was downregulated in NPC tissues and cell lines. Both XIST knockdown and miR-148a-3p overexpression promoted apoptosis, suppressed cell proliferation, migration, invasion, and EMT of NPC cells in vitro. In addition, miR-148a-3p was validated as a target of XIST, and silencing of miR-148a-3p could reverse XIST knockdown-mediated functions in SUNE-1 and CNE2 cells. Furthermore, miR-148a-3p was identified to target ADAM17, and ectopic expression of ADAM17 could abate miR-148a-3p-induced effects as well. Notably, ADAM17 was downregulated by XIST knockdown through upregulating miR-148a-3p. In vivo, XIST knockdown resulted in a slower tumor growth. ConclusionKnockdown of XIST suppresses the malignant progression of NPC cells through targeting miR-148a-3p/ADAM17 axis both in vitro and in vivo.

APLNR is involved in ATRA-induced growth inhibition of nasopharyngeal carcinoma and may suppress EMT through PI3K-Akt-mTOR signaling.

The apelin receptor (APLNR) is a GPCR involved in many pathophysiological processes; however, the correlation between APLNR expression and nasopharyngeal carcinoma (NPC) has not been reported. In this study, we used cDNA microarray data to determine APLNR expression levels in NPC tissues. We found that APLNR expression was reduced in NPC tissues compared with noncancerous nasopharyngeal epithelial tissues. Subsequently, a large-scale sample of 1015 tissues was used to validate this discovery and explore the relationship between APLNR expression and prognosis of NPC. Expression levels of APLNR in NPC tissues were indeed down-regulated. Furthermore, positive expression of APLNR in NPC predicted a better prognosis (disease-free survival: P = 0.001; overall survival: P < 0.001). Moreover, ingenuity pathway analysis revealed that an indirect interaction existed between APLNR and retinoic acid (RA) in the cancer regulatory network. Consistently, after treatment with all-trans-RA (ATRA), we found that APLNR was significantly up-regulated in NPC cell lines (5-8F and HNE1), and proliferation of NPC cells was inhibited. Cell cycle arrest occurred in the G0/G1 phase. In contrast, knockdown of APLNR diminished ATRA-induced growth inhibition of NPC cells. In addition, we surprisingly found that APLNR also played an important role in migration and invasion of NPC. Wound-healing and Transwell assays revealed that APLNR overexpression led to reduced migratory and invasive properties in 2 NPC cell lines. Western blot results revealed that hallmarks of epithelial-mesenchymal transition (EMT) were altered as well, suggesting that APLNR was capable of inhibiting EMT in NPC cells. Our study further demonstrated that low expression of APLNR promoted EMT in NPC cells by activating the PI3K-protein kinase B-mammalian target of rapamycin signaling pathway. Taken together, our data suggest that APLNR could potentially predict prognosis for patients with NPC and inhibit proliferation, migration, invasion, and EMT in nasopharyngeal cancer cells.-Liu, Y., Liu, Q., Chen, S., Liu, Y., Huang, Y., Chen, P., Li, X., Gao, G., Xu, K., Fan, S., Zeng, Z., Xiong, W., Tan, M., Li, G., Zhang, W. APLNR is involved in ATRA-induced growth inhibition of nasopharyngeal carcinoma and may suppress EMT through PI3K-Akt-mTOR signaling.

MiR-597 Targeting 14-3-3σ Enhances Cellular Invasion and EMT in Nasopharyngeal Carcinoma Cells.

Alterations in microRNAs (miRNAs) are related to the occurrence of nasopharyngeal carcinoma (NPC) and play an important role in the molecular mechanism of NPC. Our previous studies show low expression of 14-3-3σ (SFN) is related to the metastasis and differentiation of NPC, but the underlying molecular mechanisms remain unclear. Through bioinformatics analysis, we find miR-597 is the preferred target miRNA of 14-3-3σ. The expression level of 14-3-3σ in NPC cell lines was detected by Western blotting. The expression of miR-597 in NPC cell lines was detected by qRT-PCR. We transfected miR-597 mimic, miR-597 inhibitor and 14-3-3σ siRNA into 6-10B cells and then verified the expression of 14-3-3σ and EMT related proteins, including E-cadherin, N-cadherin and Vimentin by western blotting. The changes of migration and invasion ability of NPC cell lines before and after transfected were determined by wound healing assay and Transwell assay. miR-597 expression was upregulated in NPC cell lines and repaired in related NPC cell lines, which exhibit a potent tumor-forming effect. After inhibiting the miR-597 expression, its effect on NPC cell line was obviously decreased. Moreover, 14-3-3σ acts as a tumor suppressor gene and its expression in NPC cell lines is negatively correlated with miR-597. Here 14-3-3σ was identified as a downstream target gene of miR-597, and its downregulation by miR-597 drives epithelial-mesenchymal transition (EMT) and promotes the migration and invasion of NPC. Based on these findings, our study will provide theoretical and experimental evidences for molecular targeted therapy of NPC.

MiR‑495 enhances the efficacy of radiotherapy by targeting GRP78 to regulate EMT in nasopharyngeal carcinoma cells.

Glucose-regulated protein 78 (GRP78) was revealed to be associated with the radioresistance of nasopharyngeal carcinoma (NPC) in our previous study. GRP78 is a highly expressed cell surface protein, and holds great promise as a cancer specific target. Its expression may be impacted by the regulation of miRNAs, which may be involved in the radioresistance of NPC. A better understanding of the mechanisms of radioresistance may generate new targets of therapy for NPC patients. The present study was designed to investigate the effect of microRNA targeting GRP78 on the radiosensitivity of NPC. First, we used miRWalk software to predict miRNAs that may interact with GRP78. Subsequently, analysis of miR-495 and GRP78 expression was performed in the primary tissues of 92 NPC tissues and cell lines by immunohistochemistry and real-time PCR and the results revealed that miR-495 expression was lower in radioresistant NPC tissues in comparison to chronic rhinitis tissues, and also lower in radioresistant 5-8F cells (5-8F-IR) in comparison to its parental 5-8F cells. Notably, we observed an inverse association between the expression miR-495 and GRP78. Our bioinformatics analysis led to the identification of miR-495 as the optimal miRNA interacting with GRP78 mRNA. Furthermore, miR-495 targeting the 3′untranslated region (UTR) of GRP78 was detected by a Dual-Glo Luciferase Assay system. Finally, we observed that miR-495 inhibition led to a significant increase in the radioresistance of 5-8F cells and higher GRP78 expression, which may be involved in epithelial-mesenchymal transition (EMT) phenotype. miR-495 targeted the 3′UTR of GRP78 and contributed to the efficacy of radiation therapy in NPC.

Metadherin contributes to epithelial-mesenchymal transition and paclitaxel resistance induced by acidic extracellular pH in nasopharyngeal carcinoma

Paclitaxel resistance is a challenge to the treatment of nasopharyngeal carcinoma (NPC). An acidic extracellular pH (pHe), a hallmark of solid tumors, is demonstrated to decrease the efficacy of chemotherapy. However, the precise function of acidic pHe in mediating chemotherapy in NPC remains unknown. In the present study, acidic pHe significantly decreased the cytotoxicity of paclitaxel in NPC cells. In addition, epithelial-mesenchymal transition (EMT)-like changes were observed in NPC cells cultured at acidic pHe. Metadherin (MTDH), a novel oncogene, is expressed in multiple types of solid tumor, and is associated with several malignant cell characteristics, including malignant cell transformation, proliferation, angiogenesis, chemoresistance, invasion and metastasis. In the present study, MTDH expression was increased in NPC cells that had been cultured at an acidic pHe. Furthermore, the silencing of MTDH expression reversed EMT molecular marker expression and sensitized NPC cells to paclitaxel. Taken together, the results of the present study provide evidence to support an association between acidic pHe-induced paclitaxel resistance and MTDH-mediated EMT in NPC cells. Thus, targeting MTDH may provide a novel strategy for overcoming chemoresistance in NPC therapy.

Study of miR-10b regulatory mechanism for epithelial-mesenchymal transition, invasion and migration in nasopharyngeal carcinoma cells.

The aim of the study was to investigate the miR-10b regulatory mechanism for epithelial-mesenchymal transition (EMT) and its effect on the proliferation and migration of nasopharyngeal carcinoma cells. RT-qPCR was used to detect the expression of miR-10b in CNE1 nasopharyngeal carcinoma cell line. The NP69 nasopharyngeal mucosal cell line was used to determine the expression of miR-10b after infection with lentivirus. The effect of miR-10b on the proliferation of NP69 was examined using cell counting kit-8. The effect of miR-10b on NP69 migration was examined using scratch assay. Western blot analysis was used to detect the effects of miR-10b on the expression of epithelial cell markers E-cadherin and β-catenin and mesenchymal cell markers fibronectin, N-cadherin, vimentin and matrix metalloproteinase-9 (MMP-9). The present study showed that miR-10b was highly expressed in CNE1 cells. The stable expression of miR-10b promoted the proliferation and migration of NP69 cells, downregulated the expression of epithelial cell markers E-cadherin and β-catenin, and upregulated the expression of mesenchymal cell markers fibronectin, N-cadherin, vimentin and MMP-9 resulting in cell EMT. In conclusion, miR-10b promotes the proliferation and migration of nasopharyngeal carcinoma cells, and induces EMT in nasopharyngeal carcinoma cells, thereby having the potential to become a new target for the treatment of nasopharyngeal carcinoma.

The expansion and activity of myeloid-derived suppressor cells in nasopharyngeal carcinoma mediated by up-regulating COX-2 (TUM6P.964)

Abstract The expansion of myeloid-derived suppressor cells (MDSCs) is linked to tumor metastasis, but the molecular mechanism related to this link remains unclear. Here, we investigated the interactions between MDSCs and tumor cells in patients with nasopharyngeal carcinoma (NPC) and demonstrated that NPC cells induced the expansion of tumor-induced MDSCs (T-MDSCs); in turn T-MDSCs enhanced NPC cell migration and metastasis. Up-regulation of tumor cyclooxygenase-2 (COX-2) expression positively correlated with the expansion of MDSCs in NPC patients and both of COX-2 and MDSCs were poor predictors for disease-free survival. In vitro, knockdown of COX-2 expression in TW03 cells hampered T-MDSC induction by blocking IL-6. In addition, T-MDSCs promoted NPC cell proliferation, invasion and migration by triggering the epithelial-mesenchymal transition (EMT) on cell-to-cell contact; furthermore, T-MDSCs enhanced tumor lung metastasis in nude mice. Interestingly, T-MDSCs-mediated EMT was through enhancing COX-2 expression and activating the b-catenin/TCF4 pathway in NPC cells; Blockage of TGFb and iNOS significantly abolished the T-MDSC-mediated up-regulation of COX-2 and EMT in NPC cells, whereas the administration of TGFb and L-arginine supplements up-regulated COX2 expression and the b-catenin/TCF4 pathway in NPC cells. Taken together, these findings unveil a pivotal role for COX-2 in the development and cancerous contributions of MDSCs in NPC.

As an independent unfavorable prognostic factor, IL-8 promotes metastasis of nasopharyngeal carcinoma through induction of epithelial–mesenchymal transition and activation of AKT signaling

Nasopharyngeal carcinoma (NPC) has the highest metastatic potential among head and neck cancers. Distant metastasis is the major cause of treatment failure. The role of interleukin-8 (IL-8) in NPC progression remains unknown. Our multivariate survival analyses of 255 patients with NPC revealed that higher IL-8 expression in primary NPC tissue was an independent prognostic factor for overall survival, disease-free survival, and distant metastasis-free survival of the patients. In vitro study revealed that IL-8 was highly expressed in the established high-metastasis NPC clone S18 relative to the low-metastasis cells. Suppression of IL-8 by short-hairpin RNA reduced the expression of IL-8 in S18 cells and subsequently inhibited migration, invasion, and hepatic metastasis of the cells without influencing cellular growth. Overexpression of IL-8 in S26 cells resulted in increased migration, invasion, and metastasis capabilities of the cells without affecting cellular growth. Exogenous IL-8 enhanced the migration and invasion of low-metastasis CNE-2 cells in a dose-dependent manner. An epithelial–mesenchymal transition (EMT) could be induced by IL-8 in various NPC cell lines. The high level of phosphorylated AKT in S18 cells could be suppressed by knocking down IL-8 expression. Further, IL-8-promoted migration and invasion could be abolished by either the application of the phosphoinositide-3-kinase inhibitor LY294002 or the knock down of AKT expression by using small-interfering RNA. In summary, IL-8 serves as an independent prognostic indicator of overall survival, disease-free survival, and metastasis-free survival for patients with NPC. IL-8 promotes NPC metastasis via autocrine and paracrine means, involving activation of AKT signaling and inducing EMT in NPC cells.