miR-31 is consistently inactivated in EBV-associated nasopharyngeal carcinoma and contributes to its tumorigenesis

Environment factors, DNA methylation, and cancer

Today, the rapid development of science and technology and the rapid change in economy and society are changing the way of life of human beings and affecting the natural, living, working, and internal environment on which human beings depend. At the same time, the global incidence of cancer has increased significantly yearly, and cancer has become the number one killer that threatens human health. Studies have shown that diet, living habits, residential environment, mental and psychological factors, intestinal flora, genetics, social factors, and viral and non-viral infections are closely related to human cancer. However, the molecular mechanisms of the environment and cancer development remain to be further explored. In recent years, DNA methylation has become a key hub and bridge for environmental and cancer research. Some environmental factors can alter the hyper/hypomethylation of human cancer suppressor gene promoters, proto-oncogene promoters, and the whole genome, causing low/high expression or gene mutation of related genes, thereby exerting oncogenic or anticancer effects. It is expected to develop early warning markers of cancer environment based on DNA methylation, thereby providing new methods for early detection of cancers, diagnosis, and targeted therapy. This review systematically expounds on the internal mechanism of environmental factors affecting cancer by changing DNA methylation, aiming to help establish the concept of cancer prevention and improve people's health.

EBV-Associated Hub Genes as Potential Biomarkers for Predicting the Prognosis of Nasopharyngeal Carcinoma

This study aimed to develop a model using Epstein-Barr virus (EBV)-associated hub genes in order to predict the prognosis of nasopharyngeal carcinoma (NPC). Differential expression analysis, univariate regression analysis, and machine learning were performed in three microarray datasets (GSE2371, GSE12452, and GSE102349) collected from the GEO database. Three hundred and sixty-six EBV-DEGs were identified, 25 of which were found to be significantly associated with NPC prognosis. These 25 genes were used to classify NPC into two subtypes, and six genes (C16orf54, CD27, CD53, CRIP1, RARRES3, and TBC1D10C) were found to be hub genes in NPC related to immune infiltration and cell cycle regulation. It was shown that these genes could be used to predict the prognosis of NPC, with functions related to tumor proliferation and immune infiltration, making them potential therapeutic targets. The findings of this study could aid in the development of screening and prognostic methods for NPC based on EBV-related features.

Viral Encoded miRNAs in Tumorigenesis: Theranostic Opportunities in Precision Oncology

About 15% of all human cancers have a viral etiology. Although progress has been made, understanding the viral oncogenesis and associated molecular mechanisms remain complex. The discovery of cellular miRNAs has led to major breakthroughs. Interestingly, viruses have also been discovered to encode their own miRNAs. These viral, small, non-coding miRNAs are also known as viral-miRNAs (v-miRNAs). Although the function of v-miRNAs largely remains to be elucidated, their role in tumorigenesis cannot be ignored. V-miRNAs have also been shown to exploit the cellular machinery to benefit viral replication and survival. Although the discovery of Hepatitis C virus (HCV), and its viral miRNAs, is a work in progress, the existence of HPV-, EBV-, HBV-, MCPyV- and KSHV-encoded miRNA has been documented. V-miRNAs have been shown to target host factors to advance tumorigenesis, evade and suppress the immune system, and deregulate both the cell cycle and the apoptotic machinery. Although the exact mechanisms of v-miRNAs-induced tumorigenesis are still unclear, v-miRNAs are active role-players in tumorigenesis, viral latency and cell transformation. Furthermore, v-miRNAs can function as posttranscriptional gene regulators of both viral and host genes. Thus, it has been proposed that v-miRNAs may serve as diagnostic biomarkers and therapeutic targets for cancers with a viral etiology. Although significant challenges exist in their clinical application, emerging reports demonstrate their potent role in precision medicine. This review will focus on the roles of HPV-, HCV-, EBV-, HBV-, MCPyV-, and KSHV-produced v-miRNAs in tumorigenesis, as effectors in immune evasion, as diagnostic biomarkers and as novel anti-cancer therapeutic targets. Finally, it will discuss the challenges and opportunities associated with v-miRNAs theranostics in precision oncology.

Milk exosomes-mediated miR-31-5p delivery accelerates diabetic wound healing through promoting angiogenesis

The refractory diabetic wound has remained a worldwide challenge as one of the major health problems. The impaired angiogenesis phase during diabetic wound healing partly contributes to the pathological process. MicroRNA (miRNA) is an essential regulator of gene expression in crucial biological processes and is a promising nucleic acid drug in therapeutic fields of the diabetic wound. However, miRNA therapies have limitations due to lacking an effective delivery system. In the present study, we found a significant reduction of miR-31-5p expression in the full-thickness wounds of diabetic mice compared to normal mice. Further, miR-31-5p has been proven to promote the proliferation, migration, and angiogenesis of endothelial cells. Thus, we conceived the idea of exogenously supplementing miR-31-5p mimics to treat the diabetic wound. We used milk-derived exosomes as a novel system for miR-31-5p delivery and successfully encapsulated miR-31-5p mimics into milk exosomes through electroporation. Then, we proved that the miR-31-5p loaded in exosomes achieved higher cell uptake and was able to resist degradation. Moreover, our miRNA-exosomal formulation demonstrated dramatically improved endothelial cell functions in vitro, together with the promotion of angiogenesis and enhanced diabetic wound healing in vivo. Collectively, our data showed the feasibility of milk exosomes as a scalable, biocompatible, and cost-effective delivery system to enhance the bioavailability and efficacy of miRNAs.

The best choice of induction chemotherapy for patients with locally advanced nasopharyngeal carcinoma: Bayesian network meta-analysis

The determination of the optimal induction chemotherapy (IC) regimen for patients with locally advanced nasopharyngeal carcinoma (NPC) remains controversial. Eligible trials included in this Bayesian network meta-analysis were judged by synthetically evaluating survival and safety outcomes. The analysis revealed that the combined IC regimen of gemcitabine plus cisplatin (GP) gained not only the most favorable overall survival (OS) benefit but also longer distant metastasis-free survival and manageable adverse events (AEs). Additionally, combination IC regimen of mitomycin, epirubicin, cisplatin, fluorouracil, and leucovorin had insufficient significant efficacy on complete response. Docetaxel combined with cisplatin and fluorouracil induction regimen provided the first exact probability of efficacy in term of local recurrence-free survival, ranking second in OS, but accompanied by the highest rates of grade 3 or above AEs. GP regimen appears to be currently the best choice of IC regimen for combined benefit of patients with locally advanced NPC.

Viral Causality of Human Cancer and Potential Roles of Human Endogenous Retroviruses in the Multi-Omics Era: An Evolutionary Epidemiology Review

Being responsible for almost 12% of cancers worldwide, viruses are among the oldest known and most prevalent oncogenic agents. The quality of the evidence for the in vivo tumorigenic potential of microorganisms varies, thus accordingly, viruses were classified in 4 evidence-based categories by the International Agency for Research on Cancer in 2009. Since then, our understanding of the role of viruses in cancer has significantly improved, firstly due to the emergence of high throughput sequencing technologies that allowed the “brute-force” recovery of unknown viral genomes. At the same time, multi-omics approaches unravelled novel virus-host interactions in stem-cell biology. We now know that viral elements, either exogenous or endogenous, have multiple sometimes conflicting roles in human pathophysiology and the development of cancer. Here we integrate emerging evidence on viral causality in human cancer from basic mechanisms to clinical studies. We analyze viral tumorigenesis under the scope of deep-in-time human-virus evolutionary relationships and critically comment on the evidence through the eyes of clinical epidemiology, firstly by reviewing recognized oncoviruses and their mechanisms of inducing tumorigenesis, and then by examining the potential role of integrated viruses in our genome in the process of carcinogenesis.

Methylation-associated silencing of miR-9-1 promotes nasopharyngeal carcinoma progression and glycolysis via HK2

Characteristically, cancer cells metabolize glucose through aerobic glycolysis, known as the Warburg effect. Accumulating evidence suggest that during cancer formation, microRNAs (miRNAs) could regulate such metabolic reprogramming. In the present study, miR‐9‐1 was identified as significantly hypermethylated in nasopharyngeal carcinoma (NPC) cell lines and clinical tissues. Ectopic expression of miR‐9‐1 inhibited NPC cell growth and glycolytic metabolism, including reduced glycolysis, by reducing lactate production, glucose uptake, cellular glucose‐6‐phosphate levels, and ATP generation in vitro and tumor proliferation in vivo. HK2 (encoding hexokinase 2) was identified as a direct target of miR‐9‐1 using luciferase reporter assays and Western blotting. In NPC cells, hypermethylation regulates miR‐9‐1 expression and inhibits HK2 translation by directly targeting its 3' untranslated region. MiR‐9‐1 overexpression markedly reduced HK2 protein levels. Restoration of HK2 expression attenuated the inhibitory effect of miR‐9‐1 on NPC cell proliferation and glycolysis. Fluorescence in situ hybridization results indicated that miR‐9‐1 expression was an independent prognostic factor in NPC. Our findings revealed the role of the miR‐9‐1/HK2 axis in the metabolic reprogramming of NPC, providing a potential therapeutic strategy for NPC.

Role of circRNAs in viral infection and their significance for diagnosis and treatment (Review)

Circular RNAs (circRNAs) are a class of non-coding RNAs with a circular, covalent structure that lack both 5' ends and 3' poly(A) tails, which are stable and specific molecules that exist in eukaryotic cells and are highly conserved. The role of circRNAs in viral infections is being increasingly acknowledged, since circRNAs have been discovered to be involved in several viral infections (such as hepatitis B virus infection and human papilloma virus infection) through a range of circRNA/microRNA/mRNA regulatory axes. These findings have prompted investigations into the potential of circRNAs as targets for the diagnosis and treatment of viral infection-related diseases. The aim of the present review was to systematically examine and discuss the role of circRNAs in several common viral infections, as well as their potential as diagnostic markers and therapeutic targets.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

NF-κB maintains the stemness of colon cancer cells by downregulating miR-195-5p/497-5p and upregulating MCM2

BACKGROUND

Colon cancer represents one of the leading causes of gastrointestinal tumors in industrialized countries, and its incidence appears to be increasing at an alarming rate. Accumulating evidence has unveiled the contributory roles of cancer stem cells (CSCs) in tumorigenicity, recurrence, and metastases. The functions of NF-kappa B (NF-κB) activation on cancer cell survival, including colon cancer cells have encouraged us to study the role of NF-κB in the maintenance of CSCs in colon cancer.

METHODS

Tumor samples and matched normal samples were obtained from 35 colon cancer cases. CSCs were isolated from human colon cancer cell lines, where the stemness of the cells was evaluated by cell viability, colony-forming, spheroid-forming, invasion, migration, and apoptosis assays. NF-κB activation was then performed in subcutaneous tumor models of CSCs by injecting lipopolysaccharides (LPS) i.p.

RESULTS

We found that NF-κB activation could reduce the expression of miR-195-5p and miR-497-5p, where these two miRNAs were determined to be downregulated in colon cancer tissues, cultured colon CSCs, and LPS-injected subcutaneous tumor models. Elevation of miR-195-5p and miR-497-5p levels by their specific mimic could ablate the effects of NF-κB on the stemness of colon cancer cells in vivo and in vitro, suggesting that NF-κB could maintain the stemness of colon cancer cells by downregulating miR-195-5p/497-5p. MCM2 was validated as the target gene of miR-195-5p and miR-497-5p in cultured colon CSCs. Overexpression of MCM2 was shown to restore the stemness of colon cancer cells in the presence of miR-195-5p and miR-497-5p, suggesting that miR-195-5p and miR-497-5p could impair the stemness of colon cancer cells by targeting MCM2 in vivo and in vitro.

CONCLUSIONS

Our work demonstrates that the restoration of miR-195-5p and miR-497-5p may be a therapeutic strategy for colon cancer treatment in relation to NF-κB activation.

Circular RNAs in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a geographical distributed epithelial tumor of head and neck, which is prevalent in east Africa and Asia, especially southern China. Moreover, NPC has an unfavorable clinical effect and is prone to metastasis at an advanced stage. Although the recovery rate of patients has been improved due to concurrent chemoradiotherapy, poor curative effects and low overall survival remain key issues. The precise mechanisms and pivotal regulators of NPC remain still unclear. To improve the therapeutic efficacy, we focused on related-NPC circular RNAs (circRNAs). CircRNAs are a unique type of endogenous non-coding RNAs (ncRNAs) with a covalent closed-loop structure. Their expression is rich, stable and conservative. Different circRNA have specific tissue and developmental stages and can be detected in body fluids. In addition, circRNAs are involved in multiple pathological processes, especially in cancers. In recent years, using high-throughput indicator technology and bioinformatics technology, a large number of circRNAs have been identified in NPC cells and verified to have biological functions and mechanisms of action. This article aims to provide a retrospective review of the latest research on the proliferation and migration of related-NPC circRNA. Specifically, we focused on the roles and mechanisms of circRNAs in the development and progression of NPC.

CONCLUSION

CircRNA can act as an oncogene or tumor suppressor gene and participate in NPC progression (e.g., proliferation, apoptosis, migration, and invasion). In short, circRNAs have potential as biomarkers for the diagnosis, prognosis and treatment of NPC.

Down-regulation of microRNA-31 suppresses hepatic fibrosis induced by carbon tetrachloride

MicroRNA-31 (miR-31) is among the most frequently altered microRNAs in human diseases, and altered expression of miR-31 has been detected in a large variety of diseases types. miR-31 could also regulate a variety of cell functions including hepatic fibrosis. Hepatic stellate cells (HSCs) are regarded as the major cell type involved in hepatic fibrosis. Male BALB/c mice (five mice per group aged 6 weeks) received 200 μL of body weight of carbon tetrachloride (10% CCl4) mixed with olive oil intraperitoneally, and the first dose was doubled. To induce hepatic fibrosis, carbon tetrachloride was injected twice a week for 4, 6, 8, and 10 weeks. Control animals were injected with an equal volume of olive oil at the same time intervals. We found that miR-31 expression and fibrosis-related factors in four hepatic fibrosis stages. However, we noted that inhibition of miR-31 was down-regulated fibrosis-related factor expression in F1–F3 stages, but no F4 stage. Thus, we hypothesize that miR-31 may mediate hepatic fibrosis. In this research, we found that inhibition of miR-31 expression significantly inhibited HSC activation. The biological function of miR-31 during HSC activation might be through targeting hypoxia-inducible factor 1-alpha inhibitor (HIF1AN). Inhibition of miR-31 can reduce the transcription factor activity of hypoxia inducible factor 1 (HIF-1) by targeting the biological effects of HIF1AN with the condition of hypoxia. In later hepatic fibrosis could be rescue combining with inhibition of miR-31 and adding heparin-binding EGF-like growth factor (HBEGF).

Role of MicroRNAs in Treatment Response in Prostate Cancer

Prostate cancer (PCa) is the most common non-skin cancer in men worldwide, resulting in significant mortality and morbidity. Depending on the grade and stage of the cancer, patients may be given radiation therapy, hormonal therapy, or chemotherapy. However, more than half of these patients develop resistance to treatment, leading to disease progression and metastases, often with lethal consequences. MicroRNAs (miRNAs) are short, non-coding RNAs, which regulate numerous physiological as well as pathological processes, including cancer. miRNAs mediate their regulatory effect predominately by binding to the 3'-untranslated region (UTR) of their target mRNAs. In this review, we will describe the mechanisms by which miRNAs mediate resistance to radiation and drug therapy (i.e. hormone therapy and chemotherapy) in PCa, including control of apoptosis, cell growth and proliferation, autophagy, epithelial-to-mesenchymal transition (EMT), invasion and metastasis, and cancer stem cells (CSCs). Furthermore, we will discuss the utility of circulating miRNAs isolated from different body fluids of prostate cancer patients as non-invasive biomarkers of cancer detection, disease progression, and therapy response. Finally, we will shortlist the candidate miRNAs, which may have a role in drug and radioresistance, that could potentially be used as predictive biomarkers of treatment response.

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.

Knockdown of EBV-encoded circRNA circRPMS1 suppresses nasopharyngeal carcinoma cell proliferation and metastasis through sponging multiple miRNAs

Background: 

Epstein-Barr virus (EBV)-produced non-coding RNAs, including circular RNA (circRNA), regulate host cell gene expression and play important roles in development of nasopharyngeal carcinoma (NPC). EBV-encoded circRNA circRPMS1 consists of the head-to-tail splicing of exons 2-4 from the RPMS1 gene. Its roles and mechanism on NPC remain unknown.

Purpose

 In this study, we investigated the biological functions and molecular mechanisms of circRPMS1 in tumor proliferation, apoptosis, invasion, metastasis and as a potential biomarker for NPC diagnosis and prognosis.

Patients and methods

 NPC tissues and the adjacent tissues were collected. Cell proliferation assay, cell apoptosis assay, cell invasion assay, luciferase reporter assay, RNA immunoprecipitation and tumor xenograft in nude mice were performed to analyze the circRPMS1 functions.

Results: 

We found that EBV-encoded circRPMS1 was increased in metastatic NPC and was associated with short survival time. Knockdown of circRPMS1 inhibited cell proliferation, induced apoptosis and repressed cell invasion in EBV-positive NPC cells. Further mechanism investigation revealed that circRPMS1-meadiated NPC oncogenesis through sponging multiple miRNA and promoting epithelial-mesenchymal transition (EMT). The inhibitors of miR-203, miR-31 and miR-451 could reverse the effects of circRPMS1 knockdown on NPC cells.

Conclusion: 

The findings indicate circRPMS1 as a potential therapeutic target for EBV-associated NPC. Our findings provide important understanding for the further elucidation on the therapeutic use of circRNA in NPC.

The interplay between viruses & host microRNAs in cancer - An emerging role for HIV in oncogenesis

Human cancers attributed to viral infections represent a growing proportion of the global cancer burden, with these types of cancers being the leading cause of morbidity and mortality in some regions. The concept that viruses play a causal role in human cancers is not new, but the mechanism thereof, while well described for some viruses, still remains elusive and complex for others, especially in the case of HIV-associated B-cell derived cancers. In the last decade, compelling evidence has demonstrated that cellular microRNAs are deregulated in cancers, with an increasing number of studies identifying microRNAs as potential biomarkers for human cancer diagnosis, prognosis and therapeutic targets or tools. Recent research demonstrates that viruses and viral components manipulate host microRNA expressions to their advantage, and the emerging picture suggests that the virus/microRNA pathway interaction is defined by a plethora of complex mechanisms. In this review, we highlight the current knowledge on virus/microRNA pathway interactions in the context of cancer and provide new insights on HIV as an oncogenic virus.

SUN2: A potential therapeutic target in cancer

The incidence of cancer is increasing at an alarming rate despite recent advances in prevention strategies, diagnostics and therapeutics for various types of cancer. The identification of novel biomarkers to aid in prognosis and treatment for cancer is urgently required. Uncontrolled proliferation and dysregulated apoptosis are characteristics exhibited by cancer cells in the initiation of various types of cancer. Notably, aberrant expression of crucial oncogenes or cancer suppressors is a defining event in cancer occurrence. Research has demonstrated that SAD1/UNC84 domain protein-2 (SUN2) serves a suppressive role in breast cancer, atypical teratoid/rhabdoid tumors and lung cancer progression. Furthermore, SUN2 inhibits cancer cell proliferation, migration and promotes apoptosis. Recent reports have also shown that SUN2 serves prominent roles in resistance to the excessive DNA damage that destabilizes the genome and promotes cancer development, and these functions of SUN2 are critical for evading initiation of cancer. Additionally, increasing evidence has demonstrated that SUN2 is involved in maintaining cell nuclear structure and appears to be a central component for organizing the natural nuclear architecture in cancer cells. The focus of the present review is to provide an overview on the pharmacological functions of SUN2 in cancers. These findings suggest that SUN2 may serve as a promising therapeutic target and novel predictive marker in various types of cancer.

Functions and mechanisms of microRNA-31 in human cancers

MicroRNAs can exhibit opposite functions in different tumors. MiR-31 is a representative example as it can not only enhance tumor development and progression in pancreatic cancer, colorectal cancer and so on, but also inhibit tumorigenesis and induce apoptosis in ovarian cancer, prostate cancer and etc. The mechanism underlying its' pleiotropy remains unknown. Several recent studies that focused on the global gene expression changes caused by aberrant miR-31 provided information on the upstream and downstream events associated with deregulated miR-31. MiR-31 might interact with a number of signaling pathways including RAS/MARK, PI3K/AKT and RB/E2F to play its opposite functions. This review summarizes the target genes and pathways associated with miR-31 and examines the mechanisms underlying the function of miR-31. The resulting hypothesis is possible that the tissue-specific features of adenocarcinoma and squamous cell cancer and the positive feedback loop consists of miR-31 and its upstream and downstream may account for the diversity of miR-31 functions.

Integrated genomic analyses in PDX model reveal a cyclin-dependent kinase inhibitor Palbociclib as a novel candidate drug for nasopharyngeal carcinoma

Background

Patient-derived xenograft (PDX) tumor model has become a new approach in identifying druggable tumor mutations, screening and evaluating personalized cancer drugs based on the mutated targets.

Methods

We established five nasopharyngeal carcinoma (NPC) PDXs in mouse model. Subsequently, whole-exome sequencing (WES) and genomic mutation analyses were performed to search for genetic alterations for new drug targets. Potential drugs were applied in two NPC PDX mice model to assess their anti-cancer activities. RNA sequencing and transcriptomic analysis were performed in one NPC PDX mice to correlate with the efficacy of the anti-cancer drugs.

Results

A relative high incident rate of copy number variations (CNVs) of cell cycle-associated genes. Among the five NPC-PDXs, three had cyclin D1 (CCND1) amplification while four had cyclin-dependent kinase inhibitor CDKN2A deletion. Furthermore, CCND1 overexpression was observed in > 90% FFPE clinical metastatic NPC tumors (87/91) and was associated with poor outcomes. CNV analysis disclosed that plasma CCND1/CDKN2A ratio is correlated with EBV DNA load in NPC patients’ plasma and could serve as a screening test to select potential CDK4/6 inhibitor treatment candidates. Based on our NPC PDX model and RNA sequencing, Palbociclib, a cyclin-dependent kinase inhibitor, proved to have anti-tumor effects by inducing G1 arrest. One NPC patient with liver metastatic was treated with Palbociclib, had stable disease response and a drop in Epstein Barr virus (EBV) EBV titer.

Conclusions

Our integrated information of sequencing-based genomic studies and tumor transcriptomes with drug treatment in NPC-PDX models provided guidelines for personalized precision treatments and revealed a cyclin-dependent kinase inhibitor Palbociclib as a novel candidate drug for NPC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0873-5) contains supplementary material, which is available to authorized users.

Minichromosome maintenance protein 2 correlates with the malignant status and regulates proliferation and cell cycle in lung squamous cell carcinoma

Background

Minichromosome maintenance protein 2 (MCM2), which is a member of MCM family, has been found to be a relevant marker for progression and prognosis in a variety of human cancers. Due to lack of effective therapeutic target in lung squamous cell carcinoma (LUSC) patients, the aim of our study was to screen and identify biomarkers which are associated to clinicopathological characteristics including prognosis in LUSC patients.

Methods

The expression status of MCM2 in lung cancer was analyzed using the publicly available Gene Expression Omnibus databases (GSE3268 and GSE10245). The mRNA and protein expression of MCM2 in lung cancer tissues and cell lines was detected by quantitative real-time PCR and Western blot, and the association between MCM2 expression and clinicopathological factors was analyzed by immunohistochemistry. The loss-of-function study of MCM2 was conducted in LUSC cell lines.

Results

In our study, we found MCM2 expression was increased in LUSC tissues compared with paired adjacent normal lung tissues or lung adenocarcinoma tissues through analyzing microarray data sets (GSE3268 and GSE10245), which confirmed that MCM2 mRNA and protein were overexpressed in LUSC tissues and cell lines. Meanwhile, we analyzed the association between MCM2 protein expression and clinicopathological characteristics of LUSC patients, and found high expression of MCM2 protein was obviously associated with malign differentiated degree, advanced clinical stage, large tumor size, more lymph node metastasis and present distant metastasis. The survival analysis showed MCM2 overexpression was an independent unfavorable prognostic factor for LUSC patients.

Conclusion

MCM2 is involved in the development and progression of LUSC as an oncogene, and thereby may act as a potential therapeutic target for LUSC patients.

The Role of miRNAs in Virus-Mediated Oncogenesis

To date, viruses are reported to be responsible for more than 15% of all tumors worldwide. The oncogenesis could be influenced directly by the activity of viral oncoproteins or by the chronic infection or inflammation. The group of human oncoviruses includes Epstein–Barr virus (EBV), human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), human herpesvirus 8 (HHV-8) or polyomaviruses, and transregulating retroviruses such as HIV or HTLV-1. Most of these viruses express short noncoding RNAs called miRNAs to regulate their own gene expression or to influence host gene expression and thus contribute to the carcinogenic processes. In this review, we will focus on oncogenic viruses and summarize the role of both types of miRNAs, viral as well as host’s, in the oncogenesis.

DNA Tumor Virus Regulation of Host DNA Methylation and Its Implications for Immune Evasion and Oncogenesis

Viruses have evolved various mechanisms to evade host immunity and ensure efficient viral replication and persistence. Several DNA tumor viruses modulate host DNA methyltransferases for epigenetic dysregulation of immune-related gene expression in host cells. The host immune responses suppressed by virus-induced aberrant DNA methylation are also frequently involved in antitumor immune responses. Here, we describe viral mechanisms and virus–host interactions by which DNA tumor viruses regulate host DNA methylation to evade antiviral immunity, which may contribute to the generation of an immunosuppressive microenvironment during cancer development. Recent trials of immunotherapies have shown promising results to treat multiple cancers; however, a significant number of non-responders necessitate identifying additional targets for cancer immunotherapies. Thus, understanding immune evasion mechanisms of cancer-causing viruses may provide great insights for reversing immune suppression to prevent and treat associated cancers.

miR-31a-5p promotes postnatal cardiomyocyte proliferation by targeting RhoBTB1

A limited number of microRNAs (miRNAs, miRs) have been reported to control postnatal cardiomyocyte proliferation, but their strong regulatory effects suggest a possible therapeutic approach to stimulate regenerative capacity in the diseased myocardium. This study aimed to investigate the miRNAs responsible for postnatal cardiomyocyte proliferation and their downstream targets. Here, we compared miRNA profiles in cardiomyocytes between postnatal day 0 (P0) and day 10 (P10) using miRNA arrays, and found that 21 miRNAs were upregulated at P10, whereas 11 were downregulated. Among them, miR-31a-5p was identified as being able to promote cardiomyocyte proliferation as determined by proliferating cell nuclear antigen (PCNA) expression, double immunofluorescent labeling for α-actinin and 5-ethynyl-2-deoxyuridine (EdU) or Ki-67, and cell number counting, whereas miR-31a-5p inhibition could reduce their levels. RhoBTB1 was identified as a target gene of miR-31a-5p, mediating the regulatory effect of miR-31a-5p in cardiomyocyte proliferation. Importantly, neonatal rats injected with a miR-31a-5p antagomir at day 0 for three consecutive days exhibited reduced expression of markers of cardiomyocyte proliferation including PCNA expression and double immunofluorescent labeling for α-actinin and EdU, Ki-67 or phospho-histone-H3. In conclusion, miR-31a-5p controls postnatal cardiomyocyte proliferation by targeting RhoBTB1, and increasing miR-31a-5p level might be a novel therapeutic strategy for enhancing cardiac reparative processes.

MiR-130a-3p inhibits the viability, proliferation, invasion, and cell cycle, and promotes apoptosis of nasopharyngeal carcinoma cells by suppressing BACH2 expression

The aim of the present study was to explore the mechanism through which miR-130a-3p affects the viability, proliferation, migration, and invasion of nasopharyngeal carcinoma (NPC). Tissue samples were collected from the hospital department. NPC cell lines were purchased to conduct the in vitro and in vivo assays. A series of biological assays including MTT, Transwell, and wound healing assays were conducted to investigate the effects of miR-130a-3p and BACH2 on NPC cells. MiR-130a-3p was down-regulated in both NPC tissues and cell lines, whereas BACH2 was up-regulated in both tissues and cell lines. MiR-130a-3p overexpression inhibited NPC cell viability, proliferation, migration, and invasion but promoted cell apoptosis. The converse was true of BACH2, the down-regulation of which could inhibit the corresponding cell abilities and promote apoptosis of NPC cells. The target relationship between miR-130a-3p and BACH2 was confirmed. The epithelial-mesenchymal transition (EMT) pathway was also influenced by miR-130a-3p down-regulation. In conclusion, miR-130a-3p could bind to BACH2, inhibit NPC cell abilities, and promote cell apoptosis.

Minicircle-oriP-miR-31 as a Novel EBNA1-Specific miRNA Therapy Approach for Nasopharyngeal Carcinoma

MicroRNAs (miRNAs) are important post-transcriptional regulators that control cancer development and progression. However, the application of miRNA therapy in cancer has been hampered by a lack of an efficient and targeted delivery system. In our previous studies, an oriP promoter-based minicircle system successfully mediated targeted foreign gene expression in EBNA1-positive nasopharyngeal carcinoma (NPC). However, it remains to be evaluated whether this system can be applied for tumor miRNA therapy. miR-31-5p, a tumor suppressive miRNA involved in the tumorigenesis of EBV-positive NPC, was selected as the therapeutic miRNA to be transferred. In this work, we constructed a novel EBNA1-specific miRNA expression system, minicircle-oriP-miR-31. The results indicated that mc-oriP-miR-31 mediated selective miR-31-5p expression in EBNA1-positive NPC cells. Both the proliferation and migration of EBNA1-positive NPC cell lines were inhibited by mc-oriP-miR-31 treatment in vitro. Furthermore, mc-oriP-miR-31 treatment inhibited xenograft growth and lung metastasis in vivo. We also identified WDR5 as a novel miR-31-5p target. Knockdown of WDR5 inhibited NPC cell proliferation and migration and was associated with downregulation of Notch1. Reintroduction of WDR5 partially abrogated the suppressive effects induced by miR-31-5p. In conclusion, we demonstrate for the first time that targeted expression of miR-31-5p using a nonviral minicircle vector can serve as a novel approach for tumor miRNA therapy. Moreover, WDR5 may be a promising therapeutic target for NPC treatment.

Down-regulation of miR-26b induces cisplatin resistance in nasopharyngeal carcinoma by repressing JAG1

Therapy against nasopharyngeal carcinoma (NPC) is hurdled by chemoresistance. Recent studies found that microRNA (miRNA) are important regulators of cancer resistance. In this study, we aimed to explore the role and mechanism of miR‐26b in regulating NPC cisplatin (CDDP) resistance. Real‐time PCR was used to evaluate miR‐26b levels in CDDP‐resistant and CDDP‐sensitive NPC cells, as well as human NPC tissues. MiR‐26b was ectopically overexpressed in CDDP‐resistant cells, followed by monitoring changes in cell viability and apoptosis. Interaction between JAG1 and miR‐26b was characterized by dual‐luciferase reporter assay. Furthermore, we investigated whether ectopic JAG1 expression reversed CDDP sensitivity induced by miR‐26b overexpression. The effect of FOXD3 down‐regulation on miR‐26b was also evaluated. Our results indicate that miR‐26b was lower in the CDDP‐resistant NPC cells, human NPC tissue, particularly in secondary metastases. Ectopic expression of miR‐26b sensitized NPC cells to CDDP. JAG1 is a target of miR‐26b, and its expression is inversely correlated with miR‐26b. Overexpression of JAG1 reversed the CDDP sensitivity induced by miR‐26b overexpression. FOXD3 expression was also down‐regulated in CDDP‐resistant NPC. FOXD3 promoted miR‐26b expression and down‐regulation of FOXD3 suppressed miR‐26b expression. Down‐regulation of miR‐26b is closely correlated with the CDDP resistance in NPC.

The microRNA signatures: aberrantly expressed microRNAs in head and neck squamous cell carcinoma

microRNAs (miRNAs) are responsible for fine tuning the normal expression of RNA networks in human cells. Accumulating studies have demonstrated that abnormally expressed miRNAs have pivotal roles in the development of head and neck squamous cell carcinoma (HNSCC). Specifically, expression signatures of miRNAs in HNSCC have revealed dysregulated production of miRNAs and the resultant abnormal production of mRNAs and proteins. In this review, we discuss current findings regarding aberrantly expressed miRNAs and their contribution to HNSCC molecular pathogenesis.

Application of a patient-derived xenograft model in cytolytic viral activation therapy for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an Epstein Barr virus (EBV)-related malignancy in which the tumor microenvironment plays a pivotal role in tumor progression. Here, we developed two patient-derived xenograft (PDX) mouse lines from engrafted NPC metastatic tumors. Positive staining for EBV-encoded small RNAs confirmed that these tumors harbored EBV, and gene expression profile analyses further showed that the PDX was highly similar to the primary parent tumor. In vivo drug screening using the PDX system demonstrated that gemcitabine had the best antitumor effect among the tested drugs. The donor of this PDX also showed excellent responsiveness to gemcitabine treatment. The combination of gemcitabine and valproic acid exerted synergistic antitumor effects. Further addition of ganciclovir to this two-drug combination regimen enhanced cytolytic viral activation, yielding the best antitumor response among tested regimens. Treatment with this three-drug combination regimen decreased plasma EBV-DNA load, tumor viral concentration, and the number of viable tumor cells to a greater extent than the two-drug gemcitabine and valproic acid combination. These results highlight the value of PDX models in the development of EBV-targeted strategies to treat NPC.

Identification of candidate target genes of genomic aberrations in esophageal squamous cell carcinoma

The aim of the present study was to identify the candidate target genes of genomic aberrations in esophageal squamous cell carcinoma (ESCC). Array comparative genomic hybridization (CGH) and quantitative polymerase chain reaction were applied to analyze the copy number changes and expression level of candidate genes, respectively. Integrative analysis revealed that homozygous deletions of cyclin-dependent kinase inhibitor (CDKN) 2A and CDKN2B and gains of fascin actin-bundling protein 1 (FSCN1) and homer scaffolding protein 3 (HOMER3) occurred frequently in ESCC. The results demonstrated that the homozygous deletion of CDKN2A or CDKN2B was significantly associated with lymph node metastasis. Notably, the expression of CDKN2A and CDKN2B was lower in dysplasia than in normal esophageal epithelium. We also observed that the copy number increase of FSCN1 was significantly associated with pT, pN and pStage, and that the gain of HOMER3 was significantly linked with pN and pStage. We further revealed that FSCN1 and HOMER3 were overexpressed in ESCC, and that their overexpression was correlated with copy number increase. In conclusion, CDKN2A, CDKN2B, FSCN1 and HOMER3 are candidate cancer-associated genes and may play a tumorigenic role in ESCC.

Function and regulation of microRNA-31 in development and disease

MicroRNAs (miRNAs) are small noncoding RNAs that orchestrate numerous cellular processes both under normal physiological conditions as well as in diseases. This review summarizes the functional roles and transcriptional regulation of the highly evolutionarily conserved miRNA, microRNA-31 (miR-31). miR-31 is an important regulator of embryonic implantation, development, bone and muscle homeostasis, and immune system function. Its own regulation is disrupted during the onset and progression of cancer and autoimmune disorders such as psoriasis and systemic lupus erythematosus. Limited studies suggest that miR-31 is transcriptionally regulated by epigenetics, such as methylation and acetylation, as well as by a number of transcription factors. Overall, miR-31 regulates diverse cellular and developmental processes by targeting genes involved in cell proliferation, apoptosis, cell differentiation, and cell motility. Mol. Reprod. Dev. 83: 654-674, 2016 © 2016 Wiley Periodicals, Inc.

MicroRNAs serving as potential biomarkers and therapeutic targets in nasopharyngeal carcinoma: A critical review

Despite significant medical advancement, nasopharyngeal carcinoma (NPC) remains one of the most difficult cancers to detect and treat where it continues to prevail especially among the Asian population. miRNAs could act as tumour suppressor genes or oncogenes in NPC. They play important roles in the pathogenesis of NPC by regulating specific target genes which are involved in various cellular processes and pathways. In particular, studies on miRNAs related to the Epstein Barr virus (EBV)-encoded latent membrane protein one (LMP1) and EBVmiRNA- BART miRNA confirmed the link between EBV and NPC. Both miRNA and its target genes could potentially be exploited for prognostic and therapeutic strategies. They are also important in predicting the sensitivity of NPC to radiotherapy and chemotherapy. The detection of stable circulating miRNAs in plasma of NPC patients has raised the potential of miRNAs as novel diagnostic markers. To conclude, understanding the roles of miRNA in NPC will identify ways to improve the management of patients with NPC.

Epstein-Barr virus-encoded microRNA BART1 induces tumour metastasis by regulating PTEN-dependent pathways in nasopharyngeal carcinoma

Epstein–Barr virus (EBV), aetiologically linked to nasopharyngeal carcinoma (NPC), is the first human virus found to encode many miRNAs. However, how these viral miRNAs precisely regulate the tumour metastasis in NPC remains obscure. Here we report that EBV-miR-BART1 is highly expressed in NPC and closely associated with pathological and advanced clinical stages of NPC. Alteration of EBV-miR-BART1 expression results in an increase in migration and invasion of NPC cells in vitro and causes tumour metastasis in vivo. Mechanistically, EBV-miR-BART1 directly targets the cellular tumour suppressor PTEN. Reduction of PTEN dosage by EBV-miR-BART1 activates PTEN-dependent pathways including PI3K-Akt, FAK-p130^Cas and Shc-MAPK/ERK1/2 signalling, drives EMT, and consequently increases migration, invasion and metastasis of NPC cells. Reconstitution of PTEN rescues all phenotypes generated by EBV-miR-BART1, highlighting the role of PTEN in EBV-miR-BART-driven metastasis in NPC. Our findings provide new insights into the metastasis of NPC regulated by EBV and advocate for developing clinical intervention strategies against NPC.

Epstein–Barr virus is associated with nasopharyngeal carcinoma and previous studies have focused on the role of viral proteins in tumour pathology. Here, the authors show that a viral miRNA targets the host protein PTEN and has a critical role in the late stage of nasopharyngeal carcinoma by driving tumour metastasis.

Chick Chorioallantoic Membrane Assay: A 3D Animal Model for Study of Human Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a highly invasive and metastatic head and neck cancer. However, mechanistic study of the invasion and metastasis of NPC has been hampered by the lack of proper in vivo models. We established an in vivo chick embryo chorioallantoic membrane (CAM) model to study NPC tumor biology. We found 100% micro-tumor formation 3 days after inoculation with NPC cell lines (4/4) or primary tumor biopsy tissue (35/35). The transplanted NPC micro-tumors grew on CAMs with extracellular matrix interaction and induced angiogenesis. In addition, the CAM model could be used to study the growth of transplanted NPC tumors and also several important steps of metastasis, including tumor invasion by detecting the extent of basement membrane penetration, tumor angiogenesis by analyzing the area of neo-vessels, and tumor metastasis by quantifying tumor cells in distant organs. We established and described a feasible, easy-to-manipulate and reliable CAM model for in vivo study of NPC tumor biology. This model closely simulates the clinical features of NPC growth, progression and metastasis and could help elucidate the biological mechanisms of the growth pattern and invasion of NPC cells and in quantitative assessment of angiogenesis and cell intravasation.

Nasopharyngeal Carcinoma: An Evolving Role for the Epstein-Barr Virus

The Epstein-Barr herpesvirus (EBV) is an important human pathogen that is closely linked to several major malignancies including the major epithelial tumor, undifferentiated nasopharyngeal carcinoma (NPC). This important tumor occurs with elevated incidence in specific areas, particularly in southern China but also in Mediterranean Africa and some regions of the Middle East. Regardless of tumor prevalence, undifferentiated NPC is consistently associated with EBV. The consistent detection of EBV in all cases of NPC, the maintenance of the viral genome in every cell, and the continued expression of viral gene products suggest that EBV is a necessary factor for the malignant growth in vivo. However, the molecular characterization of the infection and identification of critical events have been hampered by the difficulty in developing in vitro models of NPC. Epithelial cell infection is difficult in vitro and in contrast to B-cell infection does not result in immortalization and transformation. Cell lines established from NPC usually do not retain the genome, and the successful establishment of tumor xenografts is difficult. However, critical genetic changes that contribute to the onset and progression of NPC and key molecular properties of the viral genes expressed in NPC have been identified. In some cases, viral expression becomes increasingly restricted during tumor progression and tumor cells may express only the viral nuclear antigen EBNA1 and viral noncoding RNAs. As NPC develops in the immunocompetent, the continued progression of deregulated growth likely reflects the combination of expression of viral oncogenes in some cells and viral noncoding RNAs that likely function synergistically with changes in cellular RNA and miRNA expression.

MicroRNAs in virus-induced tumorigenesis and IFN system

Numerous microRNAs (miRNAs), small non-coding RNAs encoded in the human genome, have been shown to be involved in cancer pathogenesis and progression. There is evidence that some of these miRNAs possess proapoptotic or proliferation promoting roles in the cell by negatively regulating target mRNAs. Oncogenic viruses are able to produce persistent infection, favoring tumor development by deregulating cell proliferation and inhibiting apoptosis. It has been recently suggested that cellular miRNAs may participate in host-virus interactions, influencing viral replication. Many mammalian viruses counteract this cellular antiviral defense by using viral proteins but also by encoding viral miRNAs involved in virus-induced tumorigenesis. Interferons (IFNs) modulate a number of non-coding RNA genes, especially miRNAs, that may be used by mammalian organisms as a mechanism of IFN system to combat viral infection and related diseases. In particular, IFNs might induce specific cellular miRNAs that target viral transcripts thereby using this strategy as part of their effectiveness against invading viruses. Therefore IFNs, interferon stimulated genes and miRNAs could act synergistically as innate response to virus infection to induce a potent non-permissive cellular environment for virus replication and virus-induced cancer. The relevance of this reviewed research topic is clearly related to the observation that although virus infections are responsible of specific tumors, other unidentified genetic alterations are likely involved in the induction of malignant transformation. The identification of such genetic alterations, i.e. miRNA expression in transformed cells, would be of considerable importance for the analysis of the pathogenesis and for the treatment of cancer induced by specific viruses as well as for the advancement of the current knowledge on the molecular mechanisms underlying virus-host interaction. In this respect, we will review also the important, still little explored, roles of miRNAs acting both as IFN-stimulated anti-viral molecules and as critical regulators of IFNs and IFN-stimulated genes.