Epstein-Barr virus-encoded microRNA BART1 induces tumour metastasis by regulating PTEN-dependent pathways in nasopharyngeal carcinoma. Nat Commun. 2015;6:7353. [PMID: 26135619 PMCID: PMC4507016 DOI: 10.1038/ncomms8353]

Keap1 Cystenine 151 as a Potential Target for Artemisitene-Induced Nrf2 Activation

Artemisitene (ATT) activates the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) by increasing its stabilization and reducing ubiquitination. The cysteine (Cys) residues of the cytosolic Nrf2 repressor Kelch-like ECH-associated protein-1 (Keap1) function as redox sensors and may be crucial in activating Nrf2. To determine whether ATT-induced Nrf2 activation is dependent on the modification of Keap1 and to elucidate the underlying mechanism, we transfected cell lines with six different Keap1 mutant constructs, each with a Cys (-77, -151, -257, -273, -288, and -297) to Ser substitution. Only the Cys151Ser mutant prevented ATT-mediated activation of Nrf2, indicating that the Cys151 residue of Keap1 likely interacts with ATT and is essential for Nrf2 stabilization and transcription of downstream genes. Our finding provides a pharmacological basis for using artemisitene against oxidative stress-related diseases.

A novel and non-invasive approach utilising nasal washings for the detection of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial cancer of the nasopharynx which is highly associated with Epstein-Barr virus (EBV). Worldwide, most of the top 20 countries with the highest incidence and mortality rates of NPC are low- and middle-income countries. Many studies had demonstrated that EBV could be detected in the tissue, serum and plasma of NPC patients. In this study, we explored the potential of assays based on non-invasive nasal washings (NW) as a diagnostic and prognostic tool for NPC. A total of 128 patients were evaluated for NW EBV DNA loads and a subset of these samples were also tested for 27 EBV and human miRNAs shortlisted from literature. EBV DNA and seven miRNAs showed area under the receiver operating characteristic curve (AUC) values of more than 0.7, suggestive of their potential utility to detect NPC. Logistic regression analyses suggested that combination of two NW assays that test for EBNA-1 and hsa-miR-21 had the best performance in detecting NPC. The trend of NW EBV DNA load matched with clinical outcome of 71.4% (10 out of 14) NPC patients being followed-up. In summary, the non-invasive NW testing panel may be particularly useful for NPC screening in remote areas where healthcare facilities and otolaryngologists are lacking, and may encourage frequent testing of individuals in the high risk groups who are reluctant to have their blood tested. However, further validation in an independent cohort is required to strengthen the utility of this testing panel as a non-invasive detection tool for NPC.

Cinobufotalin powerfully reversed EBV-miR-BART22-induced cisplatin resistance via stimulating MAP2K4 to antagonize non-muscle myosin heavy chain IIA/glycogen synthase 3β/β-catenin signaling pathway

BACKGROUND

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-related tumor. The role of EBV-encoding miR-BART22 is still unclear in NPC. This study aimed to identify the detailed mechanisms by which EBV-miR-BART22 functions as a tumor-promoting factor and evaluate the action of cinobufotalin in treating EBV-miR-BART22-overexpressing NPC cells.

METHODS

Using real-time PCR, western blotting, immunohistochemistry, and In situ hybridization, we detected the expression of miR-BART22 and MAP2K4 in tissues and cells, as well as evaluated their clinical relevance in NPC patients. The effects of miR-BART22 on cell metastasis, stemness and DDP chemoresistance were examined by sphere formation assay, side population analysis, transwell, boyden, in vivo xenograft tumor mouse model et al. Western blotting, immunofluorescence staining, luciferase reporter assay, ChIP, EMSA and Co-IP assay et al. were performed to explore the detailed molecular mechanism of EBV-miR-BART22 in NPC. Finally, we estimated the effects and molecular basis of Cinobufotalin on EBV-miR-BART22-overexpressing NPC cells in vitro and in vivo assays.

FINDINGS

We observed that EBV-miR-BART22 not only promoted tumor stemness and metastasis, but also enhanced the resistance to Cisplatin (DDP) in vitro and in vivo. Mechanistic analysis indicated that EBV-miR-BART22 directly targeted the MAP2K4 and upregulated non-muscle myosin heavy chain IIA (MYH9) expression by PI3K/AKT/c-Jun-induced transcription. Further, MYH9 interacted with glycogen synthase 3β(GSK3β) protein and induced its ubiquitin degradation by activating PI3K/AKT/c-Jun-induced ubiquitin transcription and the latter combined with increased TRAF6 E3 ligase, which further bound to GSK3β protein. Reductions in the GSK3β protein thus promoted β-catenin expression and nuclear translocation, which induced tumor stemness and the epithelial-to-mesenchymal transition (EMT) signals. Furthermore, we observed that cinobufotalin, a new chemically synthesized compound, significantly suppressed EBV-miR-BART22-induced DDP chemoresistance by upregulating MAP2K4 to suppress MYH9/GSK3β/β-catenin and its downstream tumor stemness and EMT signals in NPC. Finally, clinical data revealed that increased miR-BART22 and reduced MAP2K4 expression caused the poor prognoses of NPC patients.

INTERPRETATION

Our study provides a novel mechanism that cinobufotalin reversed the DDP chemoresistance and EMT induced by EBV-miR-BART22 in NPC.

Implication of viral microRNAs in the genesis and diagnosis of Epstein-Barr virus-associated tumors

The Epstein-Barr virus (EBV) is tightly associated with a variety of human tumors, including Burkitt lymphoma and acquired immune deficiency syndrome-related lymphoma of B-cell origin, as well as nasopharyngeal carcinoma and gastric cancer of epithelial origin. The virus latently infects the host cells and expresses proteins and non-coding RNAs to achieve malignancy. MicroRNAs (miRNAs or miRs) are small RNAs consisting of 19-25 nucleotides, which directly bind to the 3'-untranslated region of mRNAs to promote degradation and inhibit translation of mRNAs. EBV-encoded miRs are generated from two regions of the viral genome, within the apoptosis regulator BHRF1 gene locus and near the BamHI A region in a latency type-dependent manner. In addition, EBV-encoded miRs epigenetically regulate the expression of molecules that are effectors of the cell cycle progression, migration, apoptosis and innate immunity, serving a vital role in supporting viral replication and occurrence of EBV-associated tumors. The feasibility of using such miRs as biomarkers for the diagnosis and prognosis of EBV-associated tumors is currently under investigation.

EBV encoded miRNA BART8-3p promotes radioresistance in nasopharyngeal carcinoma by regulating ATM/ATR signaling pathway

Resistance to radiotherapy is one of the main causes of treatment failure in patients with nasopharyngeal carcinoma (NPC). Epstein-Barr virus (EBV) infection is an important factor in the pathogenesis of NPC, and EBV-encoded microRNAs (miRNAs) promote NPC progression. However, the role of EBV-encoded miRNAs in the radiosensitivity of NPC remains unclear. Here, we investigated the effects of EBV-miR-BART8-3p on radiotherapy resistance in NPC cells in vitro and in vivo, and explored the underlying molecular mechanisms. Inhibitors of ataxia telangiectasia mutated (ATM)/ataxia telangiectasia mutated and Rad3-related (ATR) (KU60019 and AZD6738, respectively) were used to examine radiotherapy resistance. We proved that EBV-miR-BART8-3p promoted NPC cell proliferation in response to irradiation in vitro and associated with the induction of cell cycle arrest at the G2/M phase, which was a positive factor for the DNA repair after radiation treatment. Besides, EBV-miR-BART8-3p could increase the size of xenograft tumors significantly in nude mice. Treatment with KU60019 or AZD6738 increased the radiosensitivity of NPC by suppressing the expression of p-ATM and p-ATR. The present results indicate that EBV-miR-BART8-3p promotes radioresistance in NPC by modulating the activity of ATM/ATR signaling pathway.

Translational genomics of nasopharyngeal cancer

Nasopharyngeal carcinoma (NPC), also named the Cantonese cancer, is a unique cancer with strong etiological association with infection of the Epstein-Barr virus (EBV). With particularly high prevalence in Southeast Asia, the involvement of EBV and genetic aberrations contributive to NPC tumorigenesis have remained unclear for decades. Recently, genomic analysis of NPC has defined it as a genetically homogeneous cancer, driven largely by NF-κB signaling caused by either somatic aberrations of NF-κB negative regulators or by overexpression of the latent membrane protein 1 (LMP1), an EBV viral oncoprotein. This represents a landmark finding of the NPC genome. Exome and RNA sequencing data from new EBV-positive NPC models also highlight the importance of PI3K pathway aberrations in NPC. We also realize for the first time that NPC mutational burden, mutational signatures, MAPK/PI3K aberrations, and MHC Class I gene aberrations, are prognostic for patient outcome. Together, these multiple genomic discoveries begin to shape the focus of NPC therapy development. Given the challenge of NF-κB targeting in human cancers, more innovative drug discovery approaches should be explored to target the unique atypical NF-κB activation feature of NPC. Our next decade of NPC research should focus on further identification of the -omic landscapes of recurrent and metastatic NPC, development of gene-based precision medicines, as well as large-scale drug screening with the newly developed and well-characterized EBV-positive NPC models. Focused preclinical and clinical investigations on these major directions may identify new and effective targeting strategies to further improve survival of NPC patients.

MicroRNAs as Therapeutic Targets in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy of epithelial origin that is prone to local invasion and early distant metastasis. Although concurrent chemotherapy and radiotherapy improves the 5-year survival outcomes, persistent or recurrent disease still occurs. Therefore, novel therapeutic targets are needed for NPC patients. MicroRNAs (miRNAs) play important roles in normal cell homeostasis, and dysregulations of miRNA expression have been implicated in human cancers. In NPC, studies have revealed that miRNAs are dysregulated and involved in tumorigenesis, metastasis, invasion, resistance to chemo- and radiotherapy, and other disease- and treatment-related processes. The advantage of miRNA-based treatment approaches is that miRNAs can concurrently target multiple effectors of pathways involved in tumor cell differentiation and proliferation. Thus, miRNA-based cancer treatments, alone or combined with standard chemotherapy and/or radiotherapy, hold promise to improve treatment response and cure rates. In this review, we will summarize the dysregulation of miRNAs in NPC initiation, progression, and treatment as well as NPC-related signaling pathways, and we will discuss the potential applications of miRNAs as biomarkers and therapeutic targets in NPC patients. We conclude that miRNAs might be potential promising therapeutic targets in nasopharyngeal carcinoma.

MiR-25-3p promotes malignant phenotypes of retinoblastoma by regulating PTEN/Akt pathway

Aberrant expression of microRNAs plays an important role in the pathogenesis and progression of retinoblastoma. MiR-25, a member of the miR-106b˜25 cluster, has been reported to be abnormally expressed in retinoblastoma, but the exact role of it remains unclear. In our study, we found that miR-25-3p was upregulated in retinoblastoma tissues and cell lines. Enforced expression of miR-25-3p in retinoblastoma cell line WERI-RB-1 increased cell growth, colony formation, anchorage-independent growth, cell migration and invasion in vitro and tumor xenograft growth in vivo. In contrast, inhibited miR-25-3p expression in retinoblastoma cell line Y79 suppressed cell growth, colony formation, anchorage-independent growth, cell migration and invasion. Through luciferase reporter assay, we found that phosphatase and tensin homolog (PTEN) was a direct target of miR-25-3p. This was verified by western blot that miR-25-3p overexpression suppressed PTEN and activated Akt signaling. In addition, miR-25-3p was found to promote epithelial-mesenchymal transition (EMT) of WERI-RB-1 cells through PTEN/Akt pathway. Western blot analysis revealed that miR-25-3p overexpression increased Vimentin and Snail expression, and suppressed E-cadherin expression, but this could be reversed by restoring PTEN. Moreover, LY294002 treatment or restoring PTEN expression abolished the effects of miR-25-3p on cell invasion, colony formation and anchorage-independent growth in vitro and tumor xenograft growth in vivo. Taken together, our results suggested that miR-25-3p promotes malignant transformation of retinoblastoma cells by suppressing PTEN.

The Function and Therapeutic Potential of Epstein-Barr Virus-Encoded MicroRNAs in Cancer

Epstein-Barr virus (EBV) is a ubiquitous human γ-herpesvirus that infects over 90% of the global population. EBV is considered a contributory factor in a variety of malignancies including nasopharyngeal carcinoma, gastric carcinoma, Burkitt lymphoma, and Hodgkin’s lymphoma. Notably, EBV was the first virus found to encode microRNAs (miRNAs). Increasing evidence indicates that EBV-encoded miRNAs contribute to the carcinogenesis and development of EBV-associated malignancies. EBV miRNAs have been shown to inhibit the expression of genes involved in cell proliferation, apoptosis, invasion, and immune signaling pathways. Therefore, EBV miRNAs perform a significant function in the complex host-virus interaction and EBV-driven carcinogenesis. However, the integrated mechanisms underlying the roles of EBV miRNAs in carcinogenesis remain to be further explored. In this review, we describe recent advances regarding the involvement of EBV miRNAs in the pathogenesis of EBV-associated malignancies and discuss their potential utility as cancer biomarkers. An in-depth investigation into the pro-carcinogenic role of EBV miRNAs will expand our knowledge of the biological processes associated with virus-driven tumors and contribute to the development of novel therapeutic strategies for the treatment of EBV-associated malignancies.

Modulation of Angiogenic Processes by the Human Gammaherpesviruses, Epstein-Barr Virus and Kaposi's Sarcoma-Associated Herpesvirus

Angiogenesis is the biological process by which new blood vessels are formed from pre-existing vessels. It is considered one of the classic hallmarks of cancer, as pathological angiogenesis provides oxygen and essential nutrients to growing tumors. Two of the seven known human oncoviruses, Epstein–Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV), belong to the Gammaherpesvirinae subfamily. Both viruses are associated with several malignancies including lymphomas, nasopharyngeal carcinomas, and Kaposi’s sarcoma. The viral genomes code for a plethora of viral factors, including proteins and non-coding RNAs, some of which have been shown to deregulate angiogenic pathways and promote tumor growth. In this review, we discuss the ability of both viruses to modulate the pro-angiogenic process.

Future of Radiotherapy in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy with unique clinical biological profiles such as associated Epstein-Barr virus infection and high radiosensitivity. Radiotherapy has long been recognized as the mainstay for the treatment of NPC. However, the further efficacy brought by radical radiotherapy has reached the bottleneck in advanced patients, who are prone to develop recurrence and distant metastasis after treatment. The application of photon therapy makes it possible for radiation dose escalation in refractory cases and may provide second chance for recurrent patients with less unrecoverable tissue damage. The concept of adaptive radiotherapy is put forward in consideration of target volume shrinkage during treatment. The replanning procedure offers better protection for the organ at risk. However, the best timing and candidates for adaptive radiotherapy is still under debate. The current tendency of artificial intelligence in NPC mainly focuses on image recognition, auto-segmentation and dose prediction. Although artificial intelligence is still in developmental stage, the future of it is promising.To further improve the efficacy of NPC, multimodality treatment is encouraged. In-depth studies on genetic and epigenetic variations help to explain the great heterogeneity among patients, and could further be applied to precise screening and prediction, personalized radiotherapy and the evolution of targeted drugs. Given the clinical benefit of immunotherapy in other cancers, the application of immunotherapy, especially immune checkpoint inhibitor, in NPC is also of great potential. Results from ongoing clinical trials combining immunotherapy with radiotherapy in NPC are expected.

Genome-wide CRISPR-based gene knockout screens reveal cellular factors and pathways essential for nasopharyngeal carcinoma

Early diagnosis of nasopharyngeal carcinoma (NPC) is difficult because of a lack of specific symptoms. Many patients have advanced disease at diagnosis, and these patients respond poorly to treatment. New treatments are therefore needed to improve the outcome of NPC. To better understand the molecular pathogenesis of NPC, here we used an NPC cell line in a genome-wide CRISPR-based knockout screen to identify the cellular factors and pathways essential for NPC (i.e. dependence factors). This screen identified the Moz, Ybf2/Sas3, Sas2, Tip60 histone acetyl transferase complex, NF-κB signaling, purine synthesis, and linear ubiquitination pathways; and MDM2 proto-oncogene as NPC dependence factors/pathways. Using gene knock out, complementary DNA rescue, and inhibitor assays, we found that perturbation of these pathways greatly reduces the growth of NPC cell lines but does not affect growth of SV40-immortalized normal nasopharyngeal epithelial cells. These results suggest that targeting these pathways/proteins may hold promise for achieving better treatment of patients with NPC.

Targeting Exosomal EBV-LMP1 Transfer and miR-203 Expression via the NF-κB Pathway: The Therapeutic Role of Aspirin in NPC

Nasopharyngeal carcinoma (NPC) is an invasive head-and-neck tumor with Epstein-Barr virus (EBV) as an important etiological cause. The EBV oncoprotein Latent membrane protein 1 (LMP1) can be trafficked into exosomes with unclear roles, and this trafficking is a potential problem in NPC control. MicroRNA-203 (miR-203) was found by us to be downregulated by LMP1, and it functions as a tumor suppressor in NPC. In this study, aspirin reversed the epithelial-mesenchymal transition (EMT) by promoting miR-203 expression in cells, and, remarkably, it repressed exosomal LMP1 (exo-LMP1) secretion from EBV-positive cells. Nuclear factor κB (NF-κB) activation was required for the exo-LMP1 production. The exo-LMP1 uptake influenced the EMT potential of EBV-negative recipient NPC cells. The exo-LMP1 level was upregulated in clinical NPC plasma samples. Aspirin treatment observably inhibited NPC lung metastasis in nude mice. The study revealed that aspirin is a promising drug for NPC therapy via its targeting of exo-LMP1 transfer and the regulatory effect of LMP1 on miR-203 expression. EBV can regulate its own tumorigenesis via the LMP1/NF-κB/exo-LMP1 axis, opening a new avenue for understanding the pathogenesis of this tumor virus. Our study also provides a rationale for the use of exo-LMP1 or exosomal miR-203 (exo-miR203) in EBV-targeted therapy by aspirin in invasive NPC.

Investigation of differentially expressed genes in nasopharyngeal carcinoma by integrated bioinformatics analysis

Nasopharyngeal carcinoma (NPC) is a common malignancy of the head and neck. The aim of the present study was to conduct an integrated bioinformatics analysis of differentially expressed genes (DEGs) and to explore the molecular mechanisms of NPC. Two profiling datasets, GSE12452 and GSE34573, were downloaded from the Gene Expression Omnibus database and included 44 NPC specimens and 13 normal nasopharyngeal tissues. R software was used to identify the DEGs between NPC and normal nasopharyngeal tissues. Distributions of DEGs in chromosomes were explored based on the annotation file and the CYTOBAND database of DAVID. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were applied. Additionally, a protein-protein interaction (PPI) network, constructed using the STRING database and visualized by Cytoscape, was used to identify hub genes, key modules and important transcription factors (TFs). A total of 906 DEGs were identified; 434 (47.90%) DEGs were upregulated and 472 (52.10%) were downregulated. The DEGs were demonstrated to be enriched in chromosome 7p15-p14, 2q31, 1q21-q22, 1q21, 4q21 and 1p31-p22. DEGs were mainly enriched for the following GO terms: 'Cilium movement', 'microtubule bundle formation' and 'axoneme assembly'. KEGG pathway enrichment analysis revealed that pathways for 'cell cycle', 'DNA replication', 'interleukin-17 signaling', 'amoebiasis' and 'glutathione metabolism' were enriched. In addition, a PPI network comprising 867 nodes and 1,241 edges was constructed. Finally, five hub genes (aurora kinase A, cell division cycle 6, mitotic arrest deficient 2-like 1, DNA topoisomerase 2α and TPX2 microtubule nucleation factor), 8 modules, and 14 TFs were identified. Modules analysis revealed that cyclin-dependent kinase 1 and exportin 1 were involved in the pathway of Epstein-Barr virus infection. In summary, the hub genes, key modules and TFs identified in this study may promote our understanding of the pathogenesis of NPC and require further in-depth investigation.

Exosomal cyclophilin A as a novel noninvasive biomarker for Epstein-Barr virus associated nasopharyngeal carcinoma

Exosomes have emerged as novel vehicles for proteins and other contents in cancer progression. Cyclophilin A (CYPA) is a pivotal member of immunophilin family. Whether CYPA can be detected in sera of nasopharyngeal carcinoma (NPC) patients remains to be explored. Epstein-Barr virus (EBV) is the first identified human tumor virus and is a causative agent of NPC. The antibody of EBV capsid antigen immunoglobulin A (EBV-VCA-IgA) is a known biomarker of NPC, with a proportion of no more than 70% being detected positively. Hence, novel biomarkers need to be discovered for early diagnosis, prognosis, and monitoring of EBV-associated NPC. A total of 110 NPC and 36 normal control serum samples were collected. Exosomes from these samples were extracted. The mRNA and protein expression levels of the above samples were validated by reverse transcription -quantitative polymerase chain reaction, Western blotting, or enzyme-linked immunosorbent assay (ELISA). Finally, the results demonstrated that both the serum and exosomal CYPA levels of NPC patients were significantly higher than that of normal cases. In addition, exosomal CYPA had a much higher level than that in the whole sera. The positive rate of EBV-VCA-IgA antibody was 68.2% in NPC sera, and noticeably, among the cases with EBV-VCA-IgA negative, 80% of them presented high levels of CYPA above the standard (cutoff value). In particular, CYPA in exosomes was uniformly with higher significance than that in whole sera. Combined analysis of CYPA protein and EBV-VCA-IgA antibody showed a greatly higher discriminatory ability in diagnosis of NPC. Moreover, exosomal CYPA level had a positive correlation with that of the EBV-encoded latent membrane protein 1 (LMP1) in exosomes. EBV-positive cancer cells secreted significantly higher levels of exosomal CYPA. This study established the utility of circulating exosomal CYPA as a potential noninvasive diagnostic biomarker for EBV-associated NPC.

MicroRNA-1224 Inhibits Tumor Metastasis in Intestinal-Type Gastric Cancer by Directly Targeting FAK

Intestinal-type gastric cancer (GC) of the Lauren classification system has specific epidemiological characteristics and carcinogenesis patterns. MicroRNAs (miRNAs) have prognostic significance, and some can be used as prognostic biomarkers in GC. In this study, we identified miR-1224 as a potential survival-related miRNA in intestinal-type GC patients by The Cancer Genome Atlas (TCGA) analysis. Using quantitative real-time PCR (qRT-PCR), we showed that the relative expression of miR-1224 was significantly decreased in intestinal-type GC tissues compared to matched adjacent normal mucosa tissues (p < 0.01). We found that high miR-1224 expression was associated with no lymph-node metastasis (p < 0.05) and good prognosis (p = 0.028) in 90 intestinal-type GC tissues. Transfection of intestinal-type GC cells with miR-1224 mimics showed that miR-1224 suppressed cell migration in vitro (wound healing assay and Transwell migration assay), whereas the transfection of cells with miR-1224 inhibitor promoted cell migration in vitro. miR-1224 also suppressed intestinal-type GC cell metastasis in a xenograft mouse model. Furthermore, bioinformatics, luciferase reporter, Western blotting, and immunohistochemistry (IHC) studies demonstrated that miR-1224 directly bound to the focal adhesion kinase (FAK) gene, and downregulated its expression, which decreased STAT3 and NF-κB signaling and subsequent the epithelial-to-mesenchymal transition (EMT). Repression of FAK is required for the miR-1224-mediated inhibition of cell migration in intestinal-type GC. The present study demonstrated that miR-1224 is downregulated in intestinal-type GC. miR-1224 inhibits the metastasis of intestinal-type GC by suppressing FAK-mediated activation of the STAT3 and NF-κB pathways, and subsequent EMT. miR-1224 could represent an important prognostic factor in intestinal-type GC.

miR-144-3p facilitates nasopharyngeal carcinoma via crosstalk with PTEN

AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSION

miR-144-3p promotes the progression of NPC by directly targeting PTEN via crosstalk with PI3K-Akt signaling.

MicroRNA in Lung Cancer Metastasis

Tumor metastasis is a hallmark of cancer, with distant metastasis frequently developing in lung cancer, even at initial diagnosis, resulting in poor prognosis and high mortality. However, available biomarkers cannot reliably predict cancer spreading sites. The metastatic cascade involves highly complicated processes including invasion, migration, angiogenesis, and epithelial-to-mesenchymal transition that are tightly controlled by various genetic expression modalities along with interaction between cancer cells and the extracellular matrix. In particular, microRNAs (miRNAs), a group of small non-coding RNAs, can influence the transcriptional and post-transcriptional processes, with dysregulation of miRNA expression contributing to the regulation of cancer metastasis. Nevertheless, although miRNA-targeted therapy is widely studied in vitro and in vivo, this strategy currently affords limited feasibility and a few miRNA-targeted therapies for lung cancer have entered into clinical trials to date. Advances in understanding the molecular mechanism of metastasis will thus provide additional potential targets for lung cancer treatment. This review discusses the current research related to the role of miRNAs in lung cancer invasion and metastasis, with a particular focus on the different metastatic lesions and potential miRNA-targeted treatments for lung cancer with the expectation that further exploration of miRNA-targeted therapy may establish a new spectrum of lung cancer treatments.

The roles of EBV-encoded microRNAs in EBV-associated tumors

Epstein-Barr virus (EBV) is believed to be a pathogen causing a number of human cancers, but the pathogenic mechanisms remain unclear. An increasing number of studies have indicated that EBV-encoded microRNAs (EBV miRNAs) are expressed in a latency type- and tumor type-dependent manner, playing important roles in the development and progression of EBV-associated tumors. By targeting one or more genes of the virus and the host, EBV miRNAs are responsible for the deregulation of a variety of viral and host cell biological processes, including viral replication, latency maintenance, immune evasion, cell apoptosis and metabolism, and tumor proliferation and metastasis. In addition, some EBV miRNAs can be used as excellent diagnostic, prognostic and treatment efficacy predictive biomarkers for EBV-associated tumors. More importantly, EBV miRNA-targeting therapeutics have emerged and have been developing rapidly, which may open a new era in the treatment of EBV-associated tumors in the near future.

Epstein–Barr Virus and Cancer

Epstein–Barr virus (EBV) contributes to about 1.5% of all cases of human cancer worldwide, and viral genes are expressed in the malignant cells. EBV also very efficiently causes the proliferation of infected human B lymphocytes. The functions of the viral proteins and small RNAs that may contribute to EBV-associated cancers are becoming increasingly clear, and a broader understanding of the sequence variation of the virus genome has helped to interpret their roles. The improved understanding of the mechanisms of these cancers means that there are great opportunities for the early diagnosis of treatable stages of EBV-associated cancers and the use of immunotherapy to target EBV-infected cells or overcome immune evasion. There is also scope for preventing disease by immunization and for developing therapeutic agents that target the EBV gene products expressed in the cancers.

Epstein-Barr virus-coded miR-BART13 promotes nasopharyngeal carcinoma cell growth and metastasis via targeting of the NKIRAS2/NF-κB pathway

Based on analysis of Epstein-Barr virus (EBV) BART microRNA expression profiles, we previously reported that EBV-encoded miR-BART13 is upregulated in nasopharyngeal carcinoma (NPC) plasma specimens. However, the effects and molecular mechanisms of miR-BART13 in NPC remain largely unknown. We found that miR-BART13 was significantly upregulated in NPC tissue specimens. Ectopic expression of miR-BART13 promoted NPC cell proliferation, epithelial mesenchymal transition, and metastasis in vitro, and facilitated xenograft tumor growth and lung metastasis in vivo. Molecularly, NF-κB inhibitor interacting Ras-like 2 (NKIRAS2), a negative regulator of the NF-κB signaling, was identified to be a direct target of miR-BART13 in NPC cells, and NKIRAS2 mRNA and protein expression was inversely correlated with miR-BART13 in NPC tissues, respecitvely. Furthermore, the NF-κB signaling pathway was activated by miR-BART13. By rescued experiments, reconstitution of NKIRAS2 expression abrogated all the phenotypes upregulated by miR-BART13, and attenuated activity of NF-κB signaling pathway activated by miR-BART13 in NPC cells. Our findings indicated the newly identified miR-BART13/NKIRAS2/NF-κB signaling axis may provide further insights into better understanding of NPC initiation and development, and targeting of this pathway could be further studied as a therapeutic strategy for NPC patients.

Epstein-Barr virus miR-BART3-3p promotes tumorigenesis by regulating the senescence pathway in gastric cancer

Epstein-Barr virus-associated gastric cancer (EBVaGC) accounts for about 10% of all gastric cancer cases and has unique pathological and molecular characteristics. EBV encodes a large number of microRNAs, which actively participate in the development of EBV-related tumors. Here, we report that EBV-miR-BART3-3p (BART3-3p) promotes gastric cancer cell growth in vitro and in vivo Moreover, BART3-3p inhibits the senescence of gastric cancer cells induced by an oncogene (RAS^G12V) or chemotherapy (irinotecan). LMP1 and EBNA3C encoded by EBV have also been reported to have antisenescence effects; however, in EBVaGC specimens, LMP1 expression is very low, and EBNA3C is not expressed. BART3-3p inhibits senescence of gastric cancer cells in a nude mouse model and inhibits the infiltration of natural killer cells and macrophages in tumor by altering the senescence-associated secretory phenotype (SASP). Mechanistically, BART3-3p directly targeted the tumor suppressor gene TP53 and caused down-regulation of p53's downstream target, p21. Analysis from clinical EBVaGC samples also showed a negative correlation between BART3-3p and TP53 expression. It is well known that mutant oncogene RAS^G12V or chemotherapeutic drugs can induce senescence, and here we show that both RAS^G12V and a chemotherapy drug also can induce BART3-3p expression in EBV-positive gastric cancer cells, forming a feedback loop that keeps the EBVaGC senescence at a low level. Our results suggest that, although TP53 is seldom mutated in EBVaGC, its expression is finely regulated such that EBV-encoded BART3-3p may play an important role by inhibiting the senescence of gastric cancer cells.

Mir20a/106a-WTX axis regulates RhoGDIa/CDC42 signaling and colon cancer progression

Wilms tumor gene on the X chromosome (WTX) is a putative tumor suppressor gene in Wilms tumor, but its expression and functions in other tumors are unclear. Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in women and the second leading cause in men in the United States. We demonstrated that WTX frequently lost in CRC which was highly correlated with cell proliferation, tumor invasion and metastasis. Mechanistically, WTX loss disrupts the interaction between RhoGDIα and CDC42 by losing of the binding with RhoGDIα and triggers the activation of CDC42 and its downstream cascades, which promotes CRC development and liver metastasis. The aberrant upregulation of miR-20a/miR-106a were identified as the reason of WTX loss in CRC both in vivo and in vitro. These study defined the mechanism how miR-20a/miR-106a-mediated WTX loss regulates CRC progression and metastasis, and provided a potential therapeutic target for preventing CRC progression.

Hypermethylation of SHISA3 Promotes Nasopharyngeal Carcinoma Metastasis by Reducing SGSM1 Stability

Altered DNA methylation is a key feature of cancer, and aberrant methylation is important in nasopharyngeal carcinoma (NPC) development. However, the methylation mechanisms underlying metastasis of NPC remain unclear. Analyzing data from public databases and conducting our own experiments, we report here that promoter hypermethylation of SHISA3 is common and contributes to the downregulation of this gene in many types of tumors, including NPC. SHISA3 suppressed NPC cell invasion and metastasis in vitro and in vivo by impeding the E3 ubiquitin ligase tripartite motif containing 21 (TRIM21)-mediated ubiquitination and degradation small G protein signaling modulator 1 (SGSM1) and by inhibiting the MAPK pathway activation. Silencing SGSM1 abrogated the inhibitory effect of SHISA3 on NPC cell migration and invasion. This newly identified SHISA3-TRIM21-SGSM1 axis could be a novel therapeutic target in NPC. SIGNIFICANCE: These findings highlight the mechanism by which a newly identified tumor suppressor SHISA3 suppresses invasion and metastasis of nasopharyngeal carcinoma.

EBV-miR-BART1-5P activates AMPK/mTOR/HIF1 pathway via a PTEN independent manner to promote glycolysis and angiogenesis in nasopharyngeal carcinoma

Abnormal metabolism and uncontrolled angiogenesis are two important characteristics of malignant tumors. The occurrence of both events involves many key molecular changes including miRNA. However, EBV encoded miRNAs are rarely mentioned as capable of regulating tumor metabolism and tumor angiogenesis. Here, we reported that one of the key miRNAs encoded by EBV, EBV-miR-Bart1-5P, can significantly promote nasopharyngeal carcinoma (NPC) cell glycolysis and induces angiogenesis in vitro and in vivo. Mechanistically, EBV-miR-Bart1-5P directly targets the α1 catalytic subunit of AMP-activated protein kinase (AMPKα1) and consequently regulates the AMPK/mTOR/HIF1 pathway which impelled NPC cell anomalous aerobic glycolysis and angiogenesis, ultimately leads to uncontrolled growth of NPC. Our findings provide new insights into metabolism and angiogenesis of NPC and new opportunities for the development of targeted NPC therapy in the future.

The Epstein-Barr virus (EBV), the first reported human tumor virus found to encode miRNAs, which closely related to malignant progression of tumors. In our study, we have observed that EBV-miR-BART1-5P, an EBV-BARTs encoded miRNA, promotes glycolysis and induces angiogenesis in NPC. Interestingly, we showed that overexpression of EBV-miR -BART1-5P and restored PTEN at the same time, did not completely reverse the phenotypes of glycolysis, angiogenesis and proliferation, suggesting that EBV-miR-BART1-5P can mediate glycolysis and induction angiogenesis by a PTEN-independent manner. Further mechanism exploration demonstrated that EBV-miR-BART1-5P has important roles in cancer cell glucose metabolism and angiogenesis by inhibiting AMPKα1 and PTEN, which provides a molecular basis for the regulation of AMPK/mTOR/HIF1 and PTEN/FAK, Shc, AKT pathways, respectively.

Detection of Epstein-Barr virus (EBV)-encoded microRNAs in plasma of patients with nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) latently infected by Epstein-Barr virus (EBV) expresses 40 EBV BART microRNAs (miRNAs). Difference in diagnostic efficacy of these miRNAs on NPC detection was observed. Here, we performed a comprehensive evaluation on the efficacy of these miRNAs.

METHODS

Quantitative polymerase chain reaction was performed on plasma nucleic acid isolated from patients with NPC and noncancer donors.

RESULTS

For primary NPC, BART2-5P, BART6-3P, BART7-3P, BART7-5P, BART9-5P, BART11-3P, BART17-5P, and BART19-5P were significantly elevated. For recurrent NPC, plasma levels of BART2-3P, BART2-5P, BART5-3P, BART5-5P, BART6-3P, BART8-3P, BART9-5P, BART17-5P, BART19-3P, and BART20-3P were significantly increased. Area under curve (AUC) analysis showed that BART19-5P had the best performance to identify NPC which was serologically EBV DNA undetectable. For recurrent NPC, BART8-3P and BART10-3P had highest AUC value for identifying cancer in EBV DNA undetectable plasma.

CONCLUSION

Our data supported the use of circulating EBV miRNAs in NPC and recurrent NPC detection.

Epstein-Barr Virus MicroRNA miR-BART5-3p Inhibits p53 Expression

Epstein-Barr virus (EBV) is the first human virus found to encode many microRNAs. It is etiologically linked to nasopharyngeal carcinoma and EBV-associated gastric carcinoma. During the latent infection period, there are only a few EBV proteins expressed, whereas EBV microRNAs, such as the BamHI-A region rightward transcript (BART) microRNAs, are highly expressed. However, how these BART miRNAs precisely regulate the tumor growth in nasopharyngeal carcinoma and gastric carcinoma remains obscure. Here, we report that upregulation of EBV-miR-BART5-3p promotes the growth of nasopharyngeal carcinoma and gastric carcinoma cells. BART5-3p directly targets the tumor suppressor gene TP53 on its 3'-untranslated region (3'-UTR) and consequently downregulates CDKN1A, BAX, and FAS expression, leading to acceleration of the cell cycle progress and inhibition of cell apoptosis. BART5-3p contributes to the resistance to chemotherapeutic drugs and ionizing irradiation-induced p53 increase. Moreover, BART5-3p also facilitates degradation of p53 proteins. BART5-3p is the first EBV-microRNA to be identified as inhibiting p53 expression and function, which suggests a novel mechanism underlying the strategies employed by EBV to maintain latent infection and promote the development of EBV-associated carcinomas.IMPORTANCE EBV encodes 44 mature microRNAs, which have been proven to promote EBV-associated diseases by targeting host genes and self-viral genes. In EBV-associated carcinomas, the expression of viral protein is limited but the expression of BART microRNAs is extremely high, suggesting that they could be major factors in the contribution of EBV-associated tumorigenesis. p53 is a critical tumor suppressor. Unlike in most human solid tumors, TP53 mutations are rare in nasopharyngeal carcinoma and EBV-associated gastric carcinoma tissues, suggesting a possibility that some EBV-encoded products suppress the functions of p53. This study provides the first evidence that a BART microRNA can suppress p53 expression by directly targeting its 3'-UTR. This study implies that EBV can use its BART microRNAs to modulate the expression of p53, thus maintaining its latency and contributing to tumorigenesis.

EBV-miR-BART8-3p induces epithelial-mesenchymal transition and promotes metastasis of nasopharyngeal carcinoma cells through activating NF-κB and Erk1/2 pathways

Background

Epstein-Barr virus (EBV) is ubiquitously associated with nasopharyngeal carcinoma (NPC). EBV encodes two groups of microRNAs (miRNAs) which are divided into BamHI fragment H rightward open reading frame 1 (BHRF1) and BamHI-A rightward transcripts (BART) microRNAs. EBV miR-BART has been found to be involved in the development and progression of NPC. However, so far the role of EBV-miR-BART8-3p in NPC progression remains unknown. This study aimed to investigate the role of EBV-miR-BART8-3p in NPC and explore the underlying mechanisms.

Methods

miRNA expression was profiled in NPC and normal nasopharyngeal mucosal specimens using miRNA sequencing. EBV-miR-BART8-3p and RNF38 expression was quantified with qPCR assay. The migration, invasion and metastasis of NPC cells were evaluated using CCK-8, colony-forming, wound-healing, and migration and invasion assays. The expression levels of epithelial-mesenchymal transition (EMT)-related markers,metastasis-related markers and NF-κB and Erk1/2 signaling proteins were determined using Western blotting. Tumorigenic assay was performed to evaluate the pulmonary metastatic ability of NPC cells in vivo.

Results

EBV BART miRNAs were highly over-expressed and co-expressed in NPC and might be associated with deactivated immune response in NPC according to the sequencing analysis. EBV-miR-BART8-3p expression was significantly higher in human NPC specimens than in normal nasopharyngeal mucosal specimens. EBV-miR-BART8-3p was found to promote NPC migration, invasion and metastasis, drove an EMT process and upregulated expression of metastasis-related proteins expression in NPC cells. Our data showed EBV-miR-BART8-3p directly targeted RNF38 in NPC cells.

Conclusion

The present study demonstrates that EBV-miR-BART8-3p plays a significant role in inducing EMT and promoting metastasis through directly targeting RNF38 in NPC cells via the activation of NF-κB and Erk1/2 signaling pathways. Our findings suggest that EBV-miR-BART8-3p is a potential therapeutic target for NPC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0953-6) contains supplementary material, which is available to authorized users.

The regulatory network of nasopharyngeal carcinoma metastasis with a focus on EBV, lncRNAs and miRNAs

Metastasis of nasopharyngeal carcinoma (NPC) remains a main cause of death for NPC patients even though great advances have been made in therapeutic approaches. An in-depth study into the molecular mechanisms of NPC metastasis will help us combat NPC. Epstein-Barr virus (EBV) infection is an evident feature of nonkeratinizing NPC and is strongly associated with tumor metastasis. Recently, long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have become a hot topic of research due to their epigenetic regulatory roles in NPC metastasis. The EBV products, lncRNAs and miRNAs can target each other and share several common signaling pathways, which form an interconnected, complex molecular regulatory network. In this review, we discuss the features of this regulatory network and summarize the molecular mechanisms of NPC metastasis, focusing on EBV, lncRNAs and miRNAs with updated knowledge.

Long noncoding RNA AFAP1-AS1 acts as a competing endogenous RNA of miR-423-5p to facilitate nasopharyngeal carcinoma metastasis through regulating the Rho/Rac pathway

BACKGROUND

Actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1), a long noncoding RNA, is significantly highly expressed and associated with metastasis and poor prognosis in many cancers, including nasopharyngeal carcinoma (NPC). In this study, we aim to identify the role of AFAP1-AS1 acting as an oncogenic lncRNA to promote NPC metastasis.

METHODS

The role of AFAP1-AS1, miR-423-5p, and FOSL2 in NPC metastasis was investigated in vitro and in vivo. Bioinformatics analysis and luciferase activity assays were used to identify the interaction between AFAP1-AS1, miR-423-5p, and FOSL2. Additionally, real-time PCR and western blotting were used to assess the function of AFAP1-AS1 acting as an oncogenic lncRNA to promote NPC progression by regulating miR-423-5p and the downstream Rho/Rac pathway.

RESULTS

In this study, we determined that AFAP1-AS1 functions as a competing endogenous RNA in NPC to regulate the Rho/Rac pathway through miR-423-5p. These interactions can mediate the expression of RAB11B, LASP1, and FOSL2 and accelerate cell migration and invasion via the Rho/Rac signaling pathway or FOSL2. AFAP1-AS1 and FOSL2 could competitively bind with miR-423-5p to regulate several molecules, including RAB11B and LASP1 of the Rho/Rac signaling pathway. AFAP1-AS1 can also regulate the expression of LASP1, which was transcriptionally regulated by FOSL2, resulting in increased migration and invasion of NPC cells via the Rho/Rac signaling pathway.

CONCLUSIONS

The observations in this study identify an important role for AFAP1-AS1 as a competing endogenous RNA (ceRNA) in NPC pathogenesis and indicate that it may serve as a potential target for cancer diagnosis and treatment.

Herpesviruses and MicroRNAs: New Pathogenesis Factors in Oral Infection and Disease?

The oral cavity incessantly encounters a plethora of microorganisms. Effective and efficient oral innate and adaptive immune responses are incumbent to maintain healthy mucosa. A higher prevalence of Human Herpesviruses (HHV), a family of large enveloped DNA viruses, has been reported in multiple oral inflammatory diseases suggesting their involvement in disease progression. However, the viral components contributing to oral disease remain obscure. MicroRNAs (miRNA) are non-protein coding, single stranded ribonucleic acid (RNA) molecules that post-transcriptionally regulate diverse messenger RNAs. Thus, miRNAs can control large repertoire of biological processes. Changes in miRNA expression are associated with various oral infections and diseases. Cellular miRNAs can act as pro- or anti-viral factors and dysregulation of host miRNA expression occurs during herpesviruses infection. This strongly suggest a critical role of cellular miRNAs in host-herpesvirus interaction. Interestingly, HHV also encode multiple miRNAs (called viral miRNAs) that may play key role in host-pathogen interaction by modulating both host biological pathways and controlling viral life cycle. Recent studies from our laboratory have identified viral miRNAs (v-miRs) in diseased oral tissue biopsies and demonstrate their immunomodulatory roles. This review discusses the association of miRNAs (both host and viral) and herpesviruses in the pathogenesis of oral inflammatory diseases.

Key elements involved in Epstein-Barr virus-associated gastric cancer and their network regulation

Background

The molecular mechanism of Epstein–Barr virus (EBV)-associated gastric cancer (EBVaGC) remains elusive. A collection of molecular regulators including transcription factor and noncoding RNA (ncRNAs) may affect the carcinogenesis of EBVaGC by regulating the expression and function of key genes. In this study, integration of multi-level expression data and bioinformatics approach was used to identify key elements and their interactions involved in mechanism of EBVaGC and their network regulation.

Methods

Data of the gene expression profiling data sets (GSE51575) was downloaded from GEO database. Differentially expressed genes between EBVaGC and normal samples were identified by GEO2R. Gene ontology and pathway enrichment analyses were performed using R packages Cluster profiler. STRING database was used to find interacting proteins between different genes. Transcription factors in differentially expressed genes were obtained from TF Checkpoint database. Using Cytoscape, we built transcription factor regulation network. miRNAs involved in the gene-interacting proteins and the miRNA-targeted lncRNA were predicted through miRWalk. Using ViRBase, EBV related miRNA regulation network was built. Overlapping genes and regulators of the above three networks were further identified, and the cross network was constructed using Cytoscape software. Moreover, the differential expressions of the target genes and transcription factors in the cross network were explored in different molecular subtypes of GC using cBioPortal. By histological verification, the expression of two main target genes in the cross network were further analyzed.

Results

A total of 104 genes showed differential expressions between EBVaGC and normal tissues, which were associated with digestion, G-protein coupled receptor binding, gastric acid secretion, etc. Pathway analysis showed that the differentially expressed genes were mainly enriched in gastric acid secretion and protein digestion and absorption. Using STRING dataset, a total of 54 proteins interacted with each other. Based on the transcription factor network, the hub transcription factors IRX3, NKX6-2, PTGER3 and SMAD5 were identified to regulate their target genes SST and GDF5, etc. After screening and matching in miRwalk datasets, a ceRNA network was established, in which the top five miRNAs were hsa-miR-4446-3p, hsa-miR-5787, hsa-miR-1915-3p, hsa-miR-335-3p and hsa-miR-6877-3p, and the top two lncRNAs were RP5-1039K5.19 and TP73-AS1. According to the EBV related miRNA regulation network, CXCL10 and SMAD5 were found to be regulated by EBV-miR-BART1-3p and EBV-mir-BART22, respectively. By overlapping the three networks, CXCL10, GDF5, PTGER3, SMAD5, miR-6877-3p, RP5-1039K5.19, TP73-AS1, EBV-miR-BART1-3p and EBV-mir-BART22 were found to be key elements of regulation mechanism of EBVaGC. CXCL10, GDF5, PTGER3 and SMAD5 were also differentially expressed among the four molecular subtypes of GC. The histological verification experiment showed differential expressions of the two main target genes GDF5 and CXCL10 between EBVaGC and non-tumor tissues as well as EBVnGC.

Conclusion

In the current study, our results revealed key elements and their interactions involved in EBVaGC. Some hub transcription factors, miRNAs, lncRNAs and EBV related miRNAs were observed to regulate their target genes. Overlapping genes and regulators were observed in diverse regulation networks, such as CXCL10, GDF5, PTGER3, SMAD5, miR-6877-3p, RP5-1039K5.19, TP73-AS1, EBV-miR-BART1-3p and EBV-mir-BART22. Moreover, CXCL10, GDF5, PTGER3 and SMAD5 were also differentially expressed among the four molecular subtypes of GC. The histological verification experiment showed differential expressions of the two main target genes GDF5 and CXCL10 between EBVaGC and non-tumor tissues as well as EBVnGC. Therefore, the identified key elements and their network regulation may be specifically involved in EBVaGC mechanisms.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0637-5) contains supplementary material, which is available to authorized users.

Single nucleotide polymorphism rs2274084 of gap junction protein beta 2 gene among Epstein-Barr virus-associated tumors

BACKGROUND

Gap junction protein beta 2 gene (GJB2) encodes one of connexins- Connexin 26 (Cx26), which mainly expressed in epithelial cells. Cx26 is usually considered a channel to exchange information between cells, which plays a critical role in tumor cell proliferation.

OBJECTIVE

We investigated GJB2 rs2274084 polymorphism in three types of tumors, including nasophoryngeal carcinoma (NPC), gastric cancer (GC) and lymphoma.

METHODS

Proteinase K digestion and phenolchloroform purification and QIAamp DNA FFPE tissue kit was used for DNA extraction. The genotype of GJB2 gene rs2274084 was detected through Sequenom MassARRAY SNP technique. The Chi-square test and Fisher's exact test were used to compare the differences between two groups.

RESULTS

The genotype frequency of GJB2 gene rs2274084 was significantly different between EBV-positive NPC and normal control (P< 0.05). However, for EBV-associated gastric cancer (EBVaGC), EBV-negative gastric cancer (EBVnGC) and lymphoma, no significant differences were found in comparison with the normal control.

CONCLUSIONS

The mutation rate of TT genotype was a risk factor to the occurrence of EBV-positive NPC.

The emerging role of Epstein-Barr virus encoded microRNAs in nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is an oncogenic herpes virus that is closely associated with the initiation and development of nasopharyngeal carcinoma (NPC), lymphoma and other malignant tumors. EBV encodes 44 mature miRNAs that regulate viral and host cell gene expression and plays a variety of roles in biological functions and the development of cancer. In this review, we summarized the biological functions and molecular mechanisms of Epstein-Barr virus-encoded microRNAs (EBV miRNAs) in tumor immune evasion, proliferation, anti-apoptosis, invasion, metastasis and as a potential biomarker for NPC diagnosis and prognosis. The knowledge generated by EBV miRNAs can be used for EBV miRNA-based precision cancer treatments in the near future.

Epstein-Barr Virus-Induced Epigenetic Pathogenesis of Viral-Associated Lymphoepithelioma-Like Carcinomas and Natural Killer/T-Cell Lymphomas

Cancer genome studies of Epstein-Barr virus (EBV)-associated tumors, including lymphoepithelioma-like carcinomas (LELC) of nasopharyngeal (NPC), gastric (EBVaGC) and lung tissues, and natural killer (NK)/T-cell lymphoma (NKTCL), reveal a unique feature of genomic alterations with fewer gene mutations detected than other common cancers. It is known now that epigenetic alterations play a critical role in the pathogenesis of EBV-associated tumors. As an oncogenic virus, EBV establishes its latent and lytic infections in B-lymphoid and epithelial cells, utilizing hijacked cellular epigenetic machinery. EBV-encoded oncoproteins modulate cellular epigenetic machinery to reprogram viral and host epigenomes, especially in the early stage of infection, using host epigenetic regulators. The genome-wide epigenetic alterations further inactivate a series of tumor suppressor genes (TSG) and disrupt key cellular signaling pathways, contributing to EBV-associated cancer initiation and progression. Profiling of genome-wide CpG methylation changes (CpG methylome) have revealed a unique epigenotype of global high-grade methylation of TSGs in EBV-associated tumors. Here, we have summarized recent advances of epigenetic alterations in EBV-associated tumors (LELCs and NKTCL), highlighting the importance of epigenetic etiology in EBV-associated tumorigenesis. Epigenetic study of these EBV-associated tumors will discover valuable biomarkers for their early detection and prognosis prediction, and also develop effective epigenetic therapeutics for these cancers.

Expression of miR-3182 and EBV-miR-BART8-3p in nasopharyngeal carcinoma is correlated with distant metastasis

Nasopharyngeal carcinoma (NPC) is an EBV associated carcinoma showing prevalence in southeast China. Distant metastasis is the major cause of death. Herein, we investigated the expressions of microRNA-3182 (miR-3182) and EBV-miR-BART8-3p in 89 cases of NPC and evaluated their correlation with clinical outcomes. Fifty-one percent of NPC showed high level expression of miR-3182. Its expression was significantly correlated with distant metastasis (P=0.005). Fifty-two percent of NPC demonstrated high level expression of EBV-miR-BART8-3p and its expression was significantly correlated with distant metastasis (P=0.006). The overall survival was influenced by the expression of miR-3182 and EBV-miR-BART8-3p. The patients with a high-level expression of miR-3182 and EBV-miR-BART8-3p had worse overall survival (P=0.005 and P=0.007). Multivariable analysis demonstrated that EBV-miR-BART8-3p was an independent prognostic factor for overall survival (P=0.018). The expression of miR-3182 was significantly correlated with EBV-miR-BART8-3p (P=0.045). In conclusion, this is the first study examining the potential clinical utility of miR-3182 and EBV-miR-BART8-3p as prognostic biomarkers in NPC. EBV infection may promote NPC progression by disrupting the expression of miR-3182.

Lactic Acid Downregulates Viral MicroRNA To Promote Epstein-Barr Virus-Immortalized B Lymphoblastic Cell Adhesion and Growth

High plasma lactate is associated with poor prognosis of many malignancies, but its role in virally mediated cancer progression and underlying molecular mechanisms are unclear. Epstein-Barr virus (EBV), the first human oncogenic virus, causes several cancers, including B-cell lymphoma. Here, we report that lactate dehydrogenase A (LDH-A) expression and lactate production are elevated in EBV-immortalized B lymphoblastic cells, and lactic acid (LA; acidic lactate) at low concentration triggers EBV-infected B-cell adhesion, morphological changes, and proliferation in vitro and in vivo Moreover, LA-induced responses of EBV-infected B cells uniquely occurs in viral latency type III, and it is dramatically associated with the inhibition of global viral microRNAs, particularly the miR-BHRF1 cluster, and the high expression of SMAD3, JUN, and COL1A genes. The introduction of miR-BHRF1-1 blocks the LA-induced effects of EBV-infected B cells. Thus, this may be a novel mechanism to explain EBV-immortalized B lymphoblastic cell malignancy in an LA microenvironment.IMPORTANCE The tumor microenvironment is complicated, and lactate, which is created by cell metabolism, contributes to an acidic microenvironment that facilitates cancer progression. However, how LA operates in virus-associated cancers is unclear. Thus, we studied how EBV (the first tumor virus identified in humans; it is associated with many cancers) upregulates the expression of LDH-A and lactate production in B lymphoma cells. Elevated LA induces adhesion and the growth of EBV-infected B cells by inhibiting viral microRNA transcription. Thus, we offer a novel understanding of how EBV utilizes an acidic microenvironment to promote cancer development.

Epstein-Barr virus-encoded microRNAs as regulators in host immune responses

Epstein-Barr virus (EBV) is an oncogenic virus that infects over 90% of the world's adult population. EBV can establish life-long latent infection in host due to the balance between EBV and host immune system. EBV latency is associated with various malignancies such as nasopharyngeal carcinoma, gastric carcinoma and Burkitt's lymphoma. EBV is the first human virus that has the capability to encode microRNAs (miRNAs). Remarkably, EBV-encoded miRNAs are abundantly expressed in latently-infected cells and serve important function in viral infection and pathogenesis. Increasing evidence indicates that EBV miRNAs target the host mRNAs involved in cell proliferation, apoptosis and transformation. EBV miRNAs also inhibit the expression of viral antigens, thereby enabling infected cells to escape immune recognition. Intriguingly, EBV miRNAs directly suppress host antiviral immunity by interfering with antigen presentation and immune cell activation. This review will update the current knowledge about EBV miRNAs implicated in host immune responses. An in-depth understanding of the functions of EBV miRNAs in host antiviral immunity will shed light on the EBV-host interactions and provide potential therapeutic targets for the treatment of EBV-associated malignancies.

Interplay of Viral Infection, Host Cell Factors and Tumor Microenvironment in the Pathogenesis of Nasopharyngeal Carcinoma

Undifferentiated nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV) infection. In addition, heavy infiltration of leukocytes is a common characteristic of EBV-associated NPC. It has long been suggested that substantial and interactive impacts between cancer and stromal cells create a tumor microenvironment (TME) to promote tumorigenesis. The coexistence of tumor-infiltrating lymphocytes with EBV-infected NPC cells represents a distinct TME which supports immune evasion and cancer development from the early phase of EBV infection. Intracellularly, EBV-encoded viral products alter host cell signaling to facilitate tumor development and progression. Intercellularly, EBV-infected cancer cells communicate with stromal cells through secretion of cytokines and chemokines, or via release of tumor exosomes, to repress immune surveillance and enhance metastasis. Although high expression of miR-BARTs has been detected in NPC patients, contributions of these more recently discovered viral products to the establishment of TME are still vaguely defined. Further investigations are needed to delineate the mechanistic linkage of the interplay between viral and host factors, especially in relation to TME, which can be harnessed in future therapeutic strategies.

Proteinase-activated receptor 2 promotes tumor cell proliferation and metastasis by inducing epithelial-mesenchymal transition and predicts poor prognosis in hepatocellular carcinoma

AIM

To clarify the role of proteinase-activated receptor 2 (PAR2) in hepatocellular carcinoma, especially in the process of metastasis.

METHODS

PAR2 expression levels were assessed by qRT-PCR and immunohistochemistry (IHC) in patient tissues and in hepatocellular carcinoma cell lines SMMC-7721 and HepG2. Cell proliferation and metastasis were assessed both in vitro and in vitro. Immunoblotting was carried out to monitor the levels of mitogen-activated protein kinase (MAPK) and epithelial-mesenchymal transition markers.

RESULTS

The prognosis was significantly poorer in patients with high PAR2 levels than in those with low PAR2 levels. Patients with high PAR2 levels had advanced tumor stage (P = 0.001, chi-square test), larger tumor size (P = 0.032, chi-square test), and high microvascular invasion rate (P = 0.037, chi-square test). The proliferation and metastasis ability of SMMC-7721 and HepG2 cells was increased after PAR2 overexpression, while knockdown of PAR2 decreased the proliferation and metastasis ability of SMMC-7721 and HepG2 cells. Knockdown of PAR2 also inhibited hepatocellular carcinoma tumor cell growth and liver metastasis in nude mice. Mechanistically, PAR2 increased the proliferation ability of SMMC-7721 and HepG2 cells via ERK activation. Activated ERK further promoted the epithelial-mesenchymal transition of these cells, which endowed them with enhanced migration and invasion ability.

CONCLUSION

These data suggest that PAR2 plays an important role in the proliferation and metastasis of hepatocellular carcinoma. Therefore, targeting PAR2 may present a favorable target for treatment of this malignancy.

LASP1 promotes nasopharyngeal carcinoma progression through negatively regulation of the tumor suppressor PTEN

LIM and SH3 protein 1 (LASP1) enhances tumor growth and metastasis in various cancers, but its role in nasopharyngeal carcinoma (NPC) remains unclear. Herein, we investigated the role of LASP1 in NPC and explored the underlying mechanisms in NPC. Clinically, overexpression of LASP1 is associated with tumor metastasis and poor prognosis of NPC patients. Gain-of-function and loss-of-function assays showed that LASP1 promoted NPC cell proliferation, metastasis, and invasion in vitro and in vivo. Mechanistically, we observed clear co-localization between LASP1 and PTEN in NPC cells. LASP1 interacted with PTEN and decreased the expression of PTEN in NPC. The ubiquitination assay indicated that LASP1 overexpression increased PTEN ubiquitination. PTEN was known as a tumor suppressor by negatively regulating phosphoinositide 3-kinase/AKT signaling pathway. Rescue experiments showed that PTEN weakened LASP1-mediated cell proliferation, migration, and invasive abilities and decreased the phosphorylation of AKT in NPC cells. Our findings suggest that LASP1 has a crucial role in NPC progression via LASP1/PTEN/AKT axis, highlighting LASP1 as a therapeutic target for NPC.

A directly negative interaction of miR-203 and ZEB2 modulates tumor stemness and chemotherapy resistance in nasopharyngeal carcinoma

miR-203 is a tumor suppressor that is disregulated in numerous malignancies including nasopharyngeal carcinoma (NPC). However, the role of miR-203 in suppressing tumor stemness, chemotherapy resistance as well as its molecular mechanisms are unclear. In this study, we observed that miR-203 suppressed cell migration, invasion, tumor stemness, and chemotherapy resistance to cisplatin (DDP) in vitro and in vivo. miR-203 exerted these effects by targeting ZEB2 and downstream epithelial-mesenchymal transition (EMT) and tumor stemness signals. Interestingly we observed that miR-203 expression was directly suppressed by ZEB2 via targeting its promoter, which significantly reduced cell migration, invasion, tumor stemness, and chemotherapy resistance in NPC cells. Finally, we found that miR-203 was negatively correlated with ZEB2 expression in NPC tissues and tumor spheres. Our data demonstrate a directly negative feedback loop between miR-203 and ZEB2 participating in tumor stemness and chemotherapy resistance, highlighting the therapeutic potential of targeting this signal for NPC chemotherapy.

Molecular subtyping of nasopharyngeal carcinoma (NPC) and a microRNA-based prognostic model for distant metastasis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a highly invasive and metastatic cancer, with diverse molecular characteristics and clinical outcomes. This study aims to dissect the molecular heterogeneity of NPC, followed by the construction of a microRNA (miRNA)-based prognostic model for prediction of distant metastasis.

METHODS

We retrieved two NPC datasets: GSE32960 and GSE70970 as training and validation cohorts, respectively. Consensus clustering was employed for cluster discovery, and support vector machine was used to build a classifier. Finally, Cox regression analysis was applied to constructing a prognostic model for predicting risk of distant metastasis.

RESULTS

Three NPC subtypes (immunogenic, classical and mesenchymal) were identified that are molecularly distinct and clinically relevant, of which mesenchymal subtype (~ 36%) is associated with poor prognosis, characterized by suppressing tumor suppressor miRNAs and the activation of epithelial--mesenchymal transition. Out of the 25 most differentially expressed miRNAs in mesenchymal subtype, miR-142, miR-26a, miR-141 and let-7i have significant prognostic power (P < 0.05).

CONCLUSIONS

We proposed for the first time that NPC can be stratified into three subtypes. Using a panel of 4 miRNAs, we established a prognostic model that can robustly stratify NPC patients into high- and low- risk groups of distant metastasis.

BART miRNAs: an unimaginable force in the development of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer that represents a major health burden in Southern China and Southeast Asia. Although the close association of NPC with Epstein-Barr virus (EBV) infection has been demonstrated, its exact role in the pathogenesis of this malignancy is still unclear. The expression of EBV-encoded microRNAs, especially BART miRNAs, which are encoded from the BamHI-A region of the viral genome, is detected at a high level in NPC. miRNAs are small noncoding mRNAs that can positively regulate the virus to ensure accurate expression of viral genomes and to modify the gene expression of host cells by negative regulation. Accumulating evidence suggests that ebv-mir-BARTs play a critical role in host cell survival, immune escape, cell proliferation, cell apoptosis, and cancer metabolism, promoting the generation of NPC. This review will summarize our current understanding of the nature and function of ebv-mir-BARTs in NPC.

Exosomes in Nasopharyngeal Carcinoma

Exosomes are nanosized (30-100nm) membrane microvesicles secreted through a complex cellular process. Exosomes contain a variety of bioactive molecules, such as proteins, microRNAs(miRNAs or miRs) and long non-coding RNAs (lncRNAs), playing an important role in the cell-to-cell substance transportation and signal transduction. Nasopharyngeal carcinoma-related exosomes (NPC-Exo) have been identified in circulating blood and contribute to tumor cell proliferation, angiopoiesis, and immune tolerance through remodeling of tumor microenvironment (TME). Nasopharyngeal carcinoma-related exosomes may also induce epithelial-mesenchymal transition (EMT), thus promoting tumor metastasis and chemoradioresistance. Clinically, the exosomes may serve as novel biomarkers for diagnosis and targeted therapies of nasopharyngeal carcinoma. This review article updates the understanding of exosomes in nasopharyngeal carcinoma(NPC).

sRNAtoolboxVM: Small RNA Analysis in a Virtual Machine

High-throughput sequencing (HTS) data for small RNAs (noncoding RNA molecules that are 20-250 nucleotides in length) can now be routinely generated by minimally equipped wet laboratories; however, the bottleneck in HTS-based research has shifted now to the analysis of such huge amount of data. One of the reasons is that many analysis types require a Linux environment but computers, system administrators, and bioinformaticians suppose additional costs that often cannot be afforded by small to mid-sized groups or laboratories. Web servers are an alternative that can be used if the data is not subjected to privacy issues (what very often is an important issue with medical data). However, in any case they are less flexible than stand-alone programs limiting the number of workflows and analysis types that can be carried out.We show in this protocol how virtual machines can be used to overcome those problems and limitations. sRNAtoolboxVM is a virtual machine that can be executed on all common operating systems through virtualization programs like VirtualBox or VMware, providing the user with a high number of preinstalled programs like sRNAbench for small RNA analysis without the need to maintain additional servers and/or operating systems.