Nm23H1 mediates tumor invasion in esophageal squamous cell carcinoma by regulation of CLDN1 through the AKT signaling

Elevated extracellular vesicular Nm23-H1 subdues the pro-migratory potential of breast cancer cell-derived extracellular vesicles

Metastasis is a key determinant in cancer mortality which is often associated with decreased levels of Nm23-H1, a well-established metastasis suppressor. Despite lacking a secretion signal peptide, Nm23-H1 has been reported to be present in the extracellular space and enclosed within extracellular vesicles (EVs). While the presence of Nm23-H1 proteins in EVs released by cancer cells has been observed through proteomics profiling, the role of vesicular Nm23-H1 remains unclear. Here, we investigated the function of vesicular Nm23-H1 using MDA-MB-231 (highly metastatic, low Nm23-H1) and MCF-7 (low/non-metastatic, high Nm23-H1) breast cancer cell models. Our findings confirm that Nm23-H1 is indeed encapsulated within EVs, and its levels can be manipulated through overexpression and knockdown approaches. Functional assays revealed that EVs derived from MDA-MB-231 cells that contained high levels of Nm23-H1 exhibit impaired pro-migratory properties, suggesting that vesicular Nm23-H1 may act as a metastasis suppressor. Furthermore, EVs with increased levels of Nm23-H1 altered the transcript levels of multiple cancer-related genes in recipient cells and stimulated type I interferon signaling through STAT1 phosphorylation. These results suggest the existence of an unconventional signaling pathway mediated by the uptake of EVs enriched with Nm23-H1, which may contribute to the anti-metastatic effect of Nm23-H1 in the tumor microenvironment. Additionally, our study demonstrates that elevated Nm23-H1 levels can impact the abundance of various other proteins encapsulated within breast cancer cell-derived EVs, such as SUSD2 (Sushi Domain Containing 2) which can also modulate metastasis.

Heat-shock protein 90α protects NME1 against degradation and suppresses metastasis of breast cancer

BACKGROUND

NME1 has been exploited as a potential translational target for decades. Substantial efforts have been made to upregulate the expression of NME1 and restore its anti-metastasis function in metastatic cancer.

METHODS

Cycloheximide (CHX) chase assay was used to measure the steady-state protein stability of NME1 and HSP90α. The NME1-associating proteins were identified by immunoprecipitation combined with mass spectrometric analysis. Gene knockdown and overexpression were employed to examine the impact of HSP90AA1 on intracellular NME1 degradation. The motility and invasiveness of breast cancer cells were examined in vitro using wound healing and transwell invasion assays. The orthotopic spontaneous metastasis and intra-venous experimental metastasis assays were used to test the formation of metastasis in vivo, respectively.

RESULTS

HSP90α interacts with NME1 and increases NME1 lifetime by impeding its ubiquitin-proteasome-mediated degradation. HSP90α overexpression significantly inhibits the metastatic potential of breast cancer cells in vitro and in vivo. A novel cell-permeable peptide, OPT22 successfully mimics the HSP90α function and prolongs the life span of endogenous NME1, resulting in reduced metastasis of breast cancer.

CONCLUSION

These results not only reveal a new mechanism of NME1 degradation but also pave the way for the development of new and effective approaches to metastatic cancer therapy.

Role of Cell-Cell Junctions in Oesophageal Squamous Cell Carcinoma

Cell-cell junctions comprise various structures, including adherens junctions, tight junctions, desmosomes, and gap junctions. They link cells to each other in tissues and regulate tissue homeostasis in critical cellular processes. Recent advances in cell-cell junction research have led to critical discoveries. Cell-cell adhesion components are important for the invasion and metastasis of tumour cells, which are not only related to cell-cell adhesion changes, but they are also involved in critical molecular signal pathways. They are of great significance, especially given that relevant molecular mechanisms are being discovered, there are an increasing number of emerging biomarkers, targeted therapies are becoming a future therapeutic concern, and there is an increased number of therapeutic agents undergoing clinical trials. Oesophageal squamous cell carcinoma (ESCC), the most common histological subtype of oesophageal cancer, is one of the most common cancers to affect epithelial tissue. ESCC progression is accompanied by the abnormal expression or localisation of components at cell-cell junctions. This review will discuss the recent scientific developments related to the molecules at cell-cell junctions and their role in ESCC to offer valuable insights for readers, provide a global view of the relationships between position, construction, and function, and give a reference for future mechanistic studies, diagnoses, and therapeutic developments.

PI3K/Akt/mTOR Signaling Pathway: Role in Esophageal Squamous Cell Carcinoma, Regulatory Mechanisms and Opportunities for Targeted Therapy

Esophageal squamous cell carcinoma (ESCC), is the most common type of esophageal cancer worldwide, mainly occurring in the Asian esophageal cancer belt, including northern China, Iran, and parts of Africa. Phosphatidlinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway is one of the most important cellular signaling pathways, which plays a crucial role in the regulation of cell growth, differentiation, migration, metabolism and proliferation. In addition, mutations in some molecules of PI3K/Akt/mTOR pathway are closely associated with survival and prognosis in ESCC patients. A large number of studies have found that there are many molecules in ESCC that can regulate the PI3K/Akt/mTOR pathway. Overexpression of these molecules often causes aberrant activation of PI3K/Akt/mTOR pathway. Currently, several effective PI3K/Akt/mTOR pathway inhibitors have been developed, which can play anticancer roles either alone or in combination with other inhibitors. This review mainly introduces the general situation of ESCC, the composition and function of PI3K/Akt/mTOR pathway, and regulatory factors that interact with PI3K/Akt/mTOR signaling pathway. Meanwhile, mutations and inhibitors of PI3K/Akt/mTOR pathway in ESCC are also elucidated.

New AKT-dependent mechanisms of anti-COVID-19 action of high-CBD Cannabis sativa extracts

COVID-19 is caused by the SARS-CoV-2 virus, which enters target cells via interactions with ACE2 and TMPRSS2. Here, we show AKT serine/threonine kinase-dependent epigenetic control of ACE2 and TMPRSS2 expression by high-cannabidiol (CBD) cannabis extracts and their individual components. CBD alone and extracts #1, #5, #7, and #129 downregulated ACE2 and TMPRSS2 in lung fibroblast WI-38 cells through AKT-mediated inhibition. miR-200c-3p and let-7a-5p were two contributing miRNAs in CBD-mediated suppression of ACE2 and TMPRSS2. CBD and terpene PTWT2.2 profoundly inhibited ACE2 and TMPRSS2 expression, both individually and in combination. Extracts #1, #5, #7, and #169 suppressed COX2 expression and remarkably attenuated TNFα/IFNγ-triggered induction of proinflammatory factors IL-6 and IL-8 by AKT pathway. The most abundant molecules present in extracts #1 and #7 modulated the expression of COX2, IL-6, and IL-8 both individually and in combination. These results reveal that high-CBD cannabis extracts attenuated ACE2 and TMPRSS2 expression and the induction of inflammatory mediators COX2, IL-6, and IL-8 via the AKT pathway, highlighting their potential anti-COVID-19 features.

LncRNA AC007255.1, an immune-related prognostic enhancer RNA in esophageal cancer

Background

Growing evidence has suggested that enhancer RNAs (eRNAs), a set of long non-coding RNAs (lncRNAs) that were derived from active enhancer regions, play critical roles in regulating gene expression in human cancers. Nevertheless potential functions of eRNAs in esophageal cancer ESCA have not yet been expounded. Here, this study aimed to explore key prognostic eRNAs in ESCA.

Methods

LncRNAs that were transcribed from active enhancer regions were analyzed utilizing the PreSTIGE algorithm, followed by prediction of their target genes. Based on the ESCA RNA-seq data from the TANRIC database, overall survival (OS)-related eRNAs were determined. The correlation between AC007255.1 expression and various clinical traits of ESCA was calculated. Functional enrichment analysis was presented based on its co-expressed genes. Based on the TIMER database, we analyzed correlations between AC007255.1 expression and immune infiltration levels. qRT-PCR was utilized to validate the expression of AC007255.1 and PRR15 in ESCA and normal tissues.

Results

Totally, 2,695 lncRNAs were transcribed from active enhancer regions. Among them, 33 were significantly related to OS. AC007255.1 was a key eRNA. PRR15 was a target gene of AC007255.1 (correlation coefficient r = 0.936). Patients with high AC007255.1 expression indicated poor OS time. There were significant correlations between AC007255.1 expression and clinical characteristics like pathological TNM, grade and stage. AC007255.1 was closely related to tight junction and neutrophil activation involved in immune response. Moreover, AC007255.1 expression was related to the infiltration levels of B cell, dendritic cell and neutrophil. qRT-PCR results confirmed that AC007255.1 and PRR15 were both up-regulated in ESCA tissues, and there was a positive correlation between the two.

Conclusion

Our findings identified a novel immune-related eRNA AC007255.1 in ESCA, which could be a promising prognostic factor for ESCA.

BRE Promotes Esophageal Squamous Cell Carcinoma Growth by Activating AKT Signaling

Brain and reproductive organ-expressed protein (BRE) is aberrantly expressed in multiple cancers; however, its expression pattern in human esophageal squamous cell carcinoma (ESCC) and its role in ESCC progression remain unclear. In this study, we aimed to investigate the expression pattern of BRE in human ESCC and its role in ESCC progression. BRE was overexpressed in ESCC tissues compared with that in the adjacent non-tumor tissues. Forced expression of BRE was sufficient to enhance ESCC cell growth by promoting cell cycle progression and anti-apoptosis. Silencing of BRE suppressed these malignant phenotypes of ESCC cells. Mechanistic evaluation revealed that BRE overexpression activated the phosphorylation of AKT, and inhibition of the AKT pathway by MK2206 decreased the BRE-induced cell growth and apoptotic resistance in ESCC cells, highlighting the critical role of AKT signaling in mediating the effects of BRE. Moreover, the effects of BRE on ESCC cell growth and AKT activation were verified in a xenograft model in vivo. The present results show that BRE is overexpressed in ESCC tissues and contributes to the growth of ESCC cells by activating AKT signaling both in vitro and in vivo and provide insight into the role of BRE in AKT signaling and ESCC pathogenesis.

Claudin-1 silencing increases sensitivity of liver cancer HepG2 cells to 5-fluorouracil by inhibiting autophagy

Liver cancer is one of the most common cancer types globally. However, the acquisition of drug resistance limits the effectiveness of chemotherapy and commonly results in metastasis. Therefore, an effective therapeutic approach to target chemoresistance-associated cellular molecules is imperative. Claudin-1 (CLDN1) has previously been reported to be associated with the development of drug resistance. The present study investigated the effect of CLDN1 on the sensitivity of 5-fluorouracil (5-FU)-resistant liver cancer cells. Firstly, a 5-FU-resistant HepG2 liver cancer cell line (Hep/5FU) was developed by continuous 5-FU treatment. MTT proliferation, Transwell and Matrigel assays indicated that Hep/5FU cells were significantly resistant to 5-FU, and demonstrated increased migration and invasion abilities, compared with parental HepG2 cells. Furthermore, reverse transcription-quantitative polymerase chain reaction and western blot analysis indicated that mRNA and protein expression levels of CLDN1 were significantly increased in Hep/5FU cells, compared with HepG2 cells. CLDN1 was knocked down by transfection with small interference RNA. MTT and Annexin V-fluorescein isothiocyanate/propidium iodide assays demonstrated that CLDN1 silencing significantly inhibits proliferation and enhances apoptosis induced by 5-FU treatment in Hep/5FU cells, compared with non-silenced Hep/5FU cells. Additionally, CLDN1 silencing attenuated the migration and invasion capabilities of Hep/5FU cells. In addition, it was identified that CLDN1 silencing decreased drug resistance by inhibiting autophagy, which was associated with a decrease in the ratio of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II/LC3-I and upregulation of P62. A cell proliferation assay revealed that the addition of autophagy inhibitor 3-methyladenine decreased drug resistance of Hep/5FU cells. By contrast, incubation with the autophagy agonist Rapamycin elevated drug resistance of CLDN1-silenced Hep/5FU cells. In summary, these data indicate that CLDN1 may be a potential target for resensitizing resistant liver cancer HepG2 cells to 5-FU by regulating cell autophagy.

Chrysin enhances anticancer drug-induced toxicity mediated by the reduction of claudin-1 and 11 expression in a spheroid culture model of lung squamous cell carcinoma cells

The aberrant expression of claudins (CLDNs), which are tight junctional proteins, is seen in various solid tumors, but the regulatory mechanisms and their pathophysiological role are not well understood. Both CLDN1 and CLDN11 were highly expressed in human lung squamous cell carcinoma (SCC). Chrysin, found in high concentration in honey and propolis, decreased CLDN1 and CLDN11 expression in RERF-LC-AI cells derived from human lung SCC. The phosphorylation level of Akt was decreased by chrysin, but those of ERK1/2 and c-Jun were not. LY-294002, an inhibitor of phosphatidylinositol 3-kinase, inhibited the phosphorylation of Akt and decreased the expression levels of CLDN1 and CLDN11. The association between phosphoinositide-dependent kinase 1 (PDK1) and Akt was inhibited by chrysin, but the phosphorylation of PDK1 was not. Immunoprecipitation and quartz-crystal microbalance assays revealed that biotinylated-chrysin binds directly to Akt. The knockdown of CLDN1 and CLDN11 using small interfering RNAs increased the transepithelial flux of doxorubicin (DXR), an anthracycline anticancer drug. Similarly, both chrysin and LY-294002 increased DXR flux. Neither CLDN1 knockdown, CLDN11 knockdown, nor chrysin changed the anticancer drug-induced cytotoxicity in a two-dimensional culture model, whereas they enhanced cytotoxicity in a spheroid culture model. Taken together, chrysin may bind to Akt and inhibit its phosphorylation, resulting in the elevation of anticancer drug-induced toxicity mediated by reductions in CLDN1 and CLDN11 expression in RERF-LC-AI cells. We suggest that chrysin may be useful as an adjuvant chemotherapy in lung SCC.

CLDN1 induces autophagy to promote proliferation and metastasis of esophageal squamous carcinoma through AMPK/STAT1/ULK1 signaling

Tight junction is a structural constitution in cell-cell adhesion and play an important role in the maintenance of permeability and integrity of normal epithelial cell barrier. The protein encoded by Claudin 1 (CLDN1), a member of the claudin family, is an integral membrane protein and a component of tight junction strands. CLDN1 has been proved to regulate the proliferation and metastasis of multiple tumors, but little is known about its role in esophageal squamous cell carcinoma (ESCC). Here, we found that CLDN1 was aberrantly increased in ESCC tissues and cell lines, and mainly distributed in the nucleus of tumor cells. Furthermore, we confirmed that CLDN1 promoted the proliferation and metastasis of ESCC by triggering autophagy both in vitro and in vivo. Mechanically, we validated that CLDN1-induced autophagy via increasing Unc-51 like autophagy activating kinase 1 (ULK1) expression through AMP-activated protein kinase (AMPK)/signal transducer and activator of transcription 1 (STAT1) signaling pathway in ESCC cells. Taken together, our findings demonstrated that aberrant expression and distribution of CLDN1 promoted the proliferation and metastasis of esophageal squamous carcinoma by triggering autophagy through AMPK/STAT1/ULK1 signaling pathway.

Overexpression of TAF1L Promotes Cell Proliferation, Migration and Invasion in Esophageal Squamous Cell Carcinoma

Currently, it reported that TAF1L gene mutation is found in a number of carcinomas, but its pathophysiological function has not been well studied. We focused on investigating expressive levels of TAF1L gene and protein in esophageal squamous cell carcinoma (ESCC) with two tissue microarrays, forty fresh paired ESCC and paracancer samples using immunohistochemistry, real-time PCR or Western blot in this study. Furthermore, we executed TAF1L silence with siRNA in ESCC cell lines to evaluate effects of TAF1L expression on cell proliferation, migration and invasion of ESCC via CCK-8, wound healing and transwell chamber assays. Moreover, key proteins related to ESCC development were also analyzed by Western blot. Results from this study showed that the expression of TAF1L mRNA and protein in ESCC tissues were significantly higher than that in matched paracancer tissues. However, its abnormal expression was not associated with other clinic features, such as the age, gender and pathological grade, except of TNM-N stage. Furthermore, the proliferation, migration and invasion of ESCC cells were inhibited after TAF1L gene silencing. As a consequence, the expression of c-Myc and phosphorylated Akt in esophageal squamous cell line after TAF1L-siRNA treatment were inversely decreased, while p53 was increased significantly, compared those to control group. Taken together, the results from this study suggest that TAF1L gene might be served as an oncogene, and its overexpression could accelerate to the tumorigenesis of ESCC via promoting the malignant cell proliferation and tumor metastasis.

8u, a pro-apoptosis/cell cycle arrest compound, suppresses invasion and metastasis through HSP90α downregulating and PI3K/Akt inactivation in hepatocellular carcinoma cells

8u, an acridine derivative, has been proved effective anti-hepatocarcinoma effect, while the underlying mechanism remains unclear. Here, metabolomics and proteomics approaches were applied to study its anti-cancer mechanism and explore its effect on HepG2 cells' invasion and metastasis abilities. The results showed that 8u significantly suppressed HepG2 cells migration and enhanced cell-to-cell junctions. The inhibition effect of 8u on invasion and metastasis disappeared after HSP90α gene silencing, and was reversed after HSP90α overexpression. The biological experimental results indicated that 8u also blocked PI3K/Akt pathway, thereby reducing fatty acid synthase (FASN) protein expression and disordering intracellular lipid metabolism to inhibit cell invasion and metastasis. In addition, HSP90α protein and PI3K/Akt pathway could co-adjust to each other. These findings demonstrated that 8u could efficiently suppress the invasion and metastasis of HepG2 cells by decreasing the expression of HSP90α protein and inhibiting the PI3K/Akt signaling pathway, which could be used as a potential candidate for the treatment of HCC.

Tumor-derived exosomes enhance invasion and metastasis of salivary adenoid cystic carcinoma cells

OBJECTIVES

Tumor-derived exosomes (TDE) have been shown to participate in different steps of the dissemination of cancer cells. However, the role of salivary adenoid cystic carcinoma-derived (SACC-derived) exosomes had not been documented in SACC. The study aims to explore the functions of SACC-derived TDE in SACC progression and investigate potential mechanisms.

METHODS

Salivary adenoid cystic carcinoma cell line SACC-83 was used to generate TDE. Afterward, SACC-83 or HUVECs were cocultured with or without TDE. Tumor migration, tumor invasion, and endothelial permeability were examined by wound healing assay, tumor invasion assay, endothelial permeability assay, and tumor cell transendothelial migration assay, respectively. Moreover, the expression levels of cell junction-related proteins were examined by qRT-PCR and Western blot.

RESULTS

Salivary adenoid cystic carcinoma -83-derived exosomes were taken up by their host cells. Meanwhile, TDE increased migration and invasion capacity of SACC-83 cells and enhanced endothelial cell permeability. Furthermore, we demonstrated that the expression of cell junction-related proteins (Claudins and ZO-1) was downregulated, which is presumably involved in the TDE-mediated promotion of migration, invasion, and metastasis.

CONCLUSION

The results suggested that SACC cell-derived exosomes were loaded with individual components that could enhance invasiveness and induce microenvironment changes, thus promoting SACC aggression.

TMPRSS4 promotes cancer stem cell traits by regulating CLDN1 in hepatocellular carcinoma

Encouraging advances in the treatment of hepatocellular carcinoma(HCC) have been achieved; however, a considerable part of patients still relapse or metastasize after therapy, and the underlying mechanisms have not been clarified yet. Here, we found that CLDN1 was markedly up-regulated in HCC tissues, and correlated with poor prognosis. Overexpression of CLDN1 dramatically promoted the capability of tumorsphere formation and cancer stem cell (CSC) traits. Furthermore, we found that TMPRSS4 was up-regulated in HCC tissues and there was a positive correlation between TMPRSS4 and CLDN1. In addition, the expression of CLDN1 was regulated by TMPRSS4. Moreover, TMPRSS4 mediated CSC properties and up-regulated CLDN1 by activating ERK1/2 signaling pathway. Taken together, our results revealed that CLDN1 contributed to CSC features of HCC, which was altered by TMPRSS4 expression via ERK1/2 signaling pathway, providing promising targets for novel specific therapies.

CLDN1 Increases Drug Resistance of Non-Small Cell Lung Cancer by Activating Autophagy via Up-Regulation of ULK1 Phosphorylation

BACKGROUND The aim of this study was to investigate the expression of CLDN1 in non-small cell lung cancer (NSCLC) and its mechanism of action in cisplatin resistance. MATERIAL AND METHODS A total of 55 patients with NSCLC admitted to our hospital between October 2013 and October 2015 were included. NSCLC tissues and tumor-adjacent tissues (≥5 cm from tumor edge) were collected. Among the 55 patients, 37 had adenocarcinoma and 18 had squamous cell carcinoma. Quantitative real-time polymerase chain reaction was used to determine mRNA expression, and protein expression was examined using Western blotting. CCK-8 assay was used to determine cell proliferation and Transwell assay was used to detect migration and invasion of the cells. Confocal microscopy was used to observe autophagosomes. RESULTS Increased CLDN1 expression promoted the development and metastasis of NSCLC. CLDN1 expression in A549/CDDP cells was up-regulated at both transcriptional and translational levels. Reduced CLDN1 expression decreased the drug resistance, proliferation, migration, and invasion abilities of A549/CDDP cells. Decreased CLDN1 expression promoted the apoptosis of A549/CDDP cells. CLDN1 enhanced CDDP drug resistance of A549 cells by activating autophagy. CLDN1 promoted the autophagy of A549 cells by up-regulating the phosphorylation level of ULK1. CONCLUSIONS The present study demonstrates that expression of CLDN1 in NSCLC is up-regulated and it is correlated with clinicopathological features. CLDN1 activates autophagy through up-regulation of ULK1 phosphorylation and promotes drug resistance of NSCLC cells to CDDP.

Overexpression of SOX4 promotes cell migration and invasion of renal cell carcinoma by inducing epithelial-mesenchymal transition

Incomplete understanding remains in the molecular mechanisms underlying progression and metastasis of renal cancer. The transcription factor SOX4 is upregulated in various human malignancies, including renal cancer, indicating it may be involved in renal tumorigenesis. In this study, we explored this hypothesis by loss-of-function and gain-of-function assays of SOX4 in renal cancer cell lines and renal epithelial cell line. We found that specific knockdown of SOX4 in renal cancer cell lines significantly suppressed the migration and invasion of cancer cells; specific overexpression of SOX4 in renal epithelial cell line markedly promoted the migration and invasion of the cell line. Epithelial-mesenchymal transition (EMT), a fundamental morphogenesis process, is implicated in renal cancer progression and metastasis. Our results demonstrated that SOX4 positively regulated the expression of mesenchymal cell markers and negatively regulated the expression of epithelial cell marker, and was involved in signal transduction pathway of TGFβ-induced EMT. In addition, SOX4 induced EMT probably through modulating the AKT/p-AKT signaling cascade. Finally, we found that SOX4 was significantly upregulated in clinical renal cancer samples compared with corresponding normal tissues and associated with EMT process in clinical samples. Taken together, our findings confirm a crucial function of SOX4 in the metastasis of renal cancer through orchestrating EMT and establish that the function suppression of SOX4-AKT-EMT axis might be an attractive therapeutic intervention during renal cancer metastasis.

miR-29a suppresses growth and migration of hepatocellular carcinoma by regulating CLDN1

CLDN1 (claudin1) is essential for intercellular junctions and has been reported to be involving in cell migration and metastasis, making it as an oncogene in various cancer types. However, the biological function roles and regulatory mechanisms of CLDN1 in hepatocellular carcinoma (HCC) are still not clarified. In this study, we found down-regulation of miR-29a and up-regulation of CLDN1 in HCC tissues and cell lines. Further found an inverse relation between the expressions of miR-29a and CLDN1 in HCC. Dual-luciferase reporter assay indicated that miR-29a regulated the expression of CLDN1 by binding to its 3' untranslated region (3'UTR). Knockdown of CLDN1 led to decrease in tumor cell growth and migration capacities in vitro and in vivo. While overexpression of miR-29a suppressed tumor growth and migration, these effects could be reversed by re-expressing CLDN1. Taken together, out data suggested that miR-29a may regulate tumor growth and migration by targeting CLDN1, providing promising therapeutic targets for HCC.

Cycling hypoxia affects cell invasion and proliferation through direct regulation of claudin1 / claudin7 expression, and indirect regulation of P18 through claudin7

Claudins (CLDNs), the major integral membrane proteins at tight junction, play critical roles in apical cell-to-cell adhesion, maintenance of epithelial polarity, and formation of impermeable barriers between epithelial cells.We investigated in this study the expression of CLDNs- Claudin1 (CLDN1) and Claudin7 (CLDN7), and their relation to tumor progression in nasopharyngeal cancer (NPC). CLDN7, rather than CLDN1, showed higher expression in both undifferentiated tumor tissue and the poorly differentiated CNE2 cells, compared with differentiated tissue and the highly differentiated CNE1 cells. Furthermore, knockdown of CLDN7 dramatically inhibited the metastasis and invasion of CNE2 cells suggesting that CLDN7 could act as a biomarker for NPC metastasis.Cycling hypoxia could induce significant changes in CLDN1 and CLDN7 expression in NPC cells. Genetics analysis demonstrated that CLDN1/CLDN7 were not only regulated directly by HIF1a but also affected each other through a feedback mechanism. CLDN7 acted as a bridge to promote HIF1a-induced P18 expression and cell differentiation. Taken together, our results provide evidence that adjusting the oxygenation time and cycles in NPC might be an effective method to prevent / delay the metastasis of poorly differentiated NPC cells.