RESUMEN
Epstein-Barr virus (EBV) encodes BamHIA rightward transcript (BART) microRNAs (miRNAs). These miRNAs are expressed at high levels in epithelial tumors, such as nasopharyngeal carcinoma (NPC). BART miRNAs play important roles in EBV-associated malignancies, however, the reason for their high expression in NPC is unclear. We performed multiple sequence alignment of six completely sequenced EBV strains: Akata, YCCEL1, SNU719, C666-1, Mutu I, and M81. A single-nucleotide deletion was identified at the promoter region of BART. The luciferase assay suggested that this single-nucleotide polymorphism (SNP) significantly increased BART promoter activity. In addition to deletion, substitution at the same site also increased BART promoter activity. Analysis of the 170 EBV genome sequences from NPC and EBV-associated gastric cancers revealed that the frequency of this SNP was associated with NPC incidence and this SNP was found to be accumulated in the BART promoter region. Overall, our results suggested that this SNP should enhance BART promoter activity and thus, might contribute to the development of EBV-associated epithelial malignancies.
Asunto(s)
Herpesvirus Humano 4/genética , Carcinoma Nasofaríngeo/virología , Neoplasias Nasofaríngeas/virología , Polimorfismo de Nucleótido Simple , Línea Celular Tumoral , Infecciones por Virus de Epstein-Barr/virología , Regulación Viral de la Expresión Génica , Herpesvirus Humano 4/patogenicidad , Humanos , MicroARNs/genética , Regiones Promotoras GenéticasRESUMEN
[This corrects the article DOI: 10.3389/fimmu.2020.00367.].
RESUMEN
Epstein-Barr virus (EBV) is an oncogenic human herpes virus that was discovered in 1964. Viral non-coding RNAs, such as BamHI-A rightward fragment-derived microRNAs (BART miRNAs) or BamHI-H rightward fragment 1-derived miRNAs (BHRF1 miRNA) in EBV-infected cells have been recently reported. Host miRNAs are also upregulated upon EBV infection. Viral and host miRNAs are important in maintaining viral infection and evasion of host immunity. Although miRNAs in EBV-infected cells often promote cell proliferation by targeting apoptosis or cell cycle, this review focuses on the regulation of the recognition of the host immune system. This review firstly describes the location and organization of two clusters of viral miRNAs, then describes evasion from host immune surveillance systems by modulating viral gene expression or inhibiting innate and acquired immunity by viral miRNAs as well as host miRNAs. Another topic is the enigmatic depletion of viral miRNAs in several types of EBV-infected tumor cells. Finally, this review introduces the strong correlation of nasopharyngeal cancer cases with a newly identified single nucleotide polymorphism that enhances BART miRNA promoter activity.
Asunto(s)
Infecciones por Virus de Epstein-Barr/inmunología , Regulación Viral de la Expresión Génica , Herpesvirus Humano 4/genética , Interacciones Huésped-Patógeno/inmunología , MicroARNs/inmunología , ARN Viral/inmunología , Inmunidad Adaptativa/genética , Empalme Alternativo , Carcinoma/genética , Carcinoma/inmunología , Carcinoma/virología , Efecto Citopatogénico Viral/genética , Células Epiteliales/virología , Infecciones por Virus de Epstein-Barr/genética , Herpesvirus Humano 4/inmunología , Herpesvirus Humano 4/fisiología , Interacciones Huésped-Patógeno/genética , Humanos , Evasión Inmune/genética , Inmunidad Innata/genética , Vigilancia Inmunológica , Linfoma/genética , Linfoma/inmunología , Linfoma/virología , MicroARNs/genética , Neoplasias Nasofaríngeas/genética , Neoplasias Nasofaríngeas/inmunología , Neoplasias Nasofaríngeas/virología , Polimorfismo de Nucleótido Simple , Regiones Promotoras Genéticas , ARN Viral/genética , Proteínas de la Matriz Viral/fisiología , Proteínas Virales/biosíntesis , Proteínas Virales/genética , Proteínas Virales/inmunología , Latencia del Virus/genética , Latencia del Virus/inmunologíaRESUMEN
Although Epstein-Barr virus (EBV) is known to encode over 40 different miRNAs of its own, the roles of most EBV miRNAs remain unknown. Disabled homolog 2 (DAB2) is a putative tumor suppressor, but its role in gastric carcinoma (GC), especially in EBV-associated GC, needs to be clarified. Our qRT-PCR and mRNA microarray results showed that DAB2 expression was down-regulated in EBV-positive GC cells compared to EBV-negative cells. Four BART miRNAs that might target DAB2 were predicted, and we found, using a luciferase reporter assay, that miR-BART1-3p directly targeted the 3'-UTR of DAB2. The miR-BART1-3p transfection decreased DAB2 expression at both mRNA and protein levels, while transfection of an inhibitor of miR-BART1-3p, miR-BART1-3p(i), increased DAB2 expression. In addition, miR-BART1-3p as well as siDAB2 increased migration and decreased apoptosis. Meanwhile, miR-BART1-3p(i) or pcDNA3.1-DAB2 transfection decreased migration and increased apoptosis in EBV-infected GC cells. Furthermore, decreased migration by miR-BART1-3p(i) was abrogated by co-transfected siDAB2, while decreased migration by miR-BART1-3p(i) was further suppressed by a co-transfected DAB2 over-expression vector. Our data suggest that miR-BART1-3p plays an important role in the tumorigenesis of EBV-associated GC by directly targeting DAB2.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Reguladoras de la Apoptosis/metabolismo , Apoptosis/fisiología , Movimiento Celular/fisiología , Proliferación Celular/fisiología , MicroARNs/fisiología , Proteínas Adaptadoras Transductoras de Señales/genética , Apoptosis/genética , Proteínas Reguladoras de la Apoptosis/genética , Western Blotting , Movimiento Celular/genética , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica/genética , Regulación Neoplásica de la Expresión Génica/fisiología , Células HEK293 , Humanos , MicroARNs/genética , ARN Interferente Pequeño/genética , Cicatrización de Heridas/genética , Cicatrización de Heridas/fisiologíaRESUMEN
In Epstein-Barr virus (EBV)-infected epithelial cancers, BamHI A rightward transcript (BART) miRNAs are highly expressed. However, only a few target genes of BART miRNAs have been investigated. Our mRNA microarray data showed that DKK1 was markedly down-regulated in EBV-associated gastric carcinoma (EBVaGC) cells. Using luciferase reporter assay we tested whether miR-BART10-3p regulates DKK1 by directly targeting the 3'-UTR of DKK1 mRNA. We observed that miR-BART10-3p transfection decreased DKK1 expression, while an LNA inhibitor of miR-BART10-3p (LNA-miR-BART10-3p(i)) increased DKK1 expression. Furthermore, miR-BART10-3p and siDKK1 promoted cell proliferation and migration. In contrast, transfecting GC cells with LNA-miR-BART10-3p(i) or DKK1 over expression vector suppressed cell proliferation and migration. Our results suggest that miR-BART10-3p may be involved in the tumor progression of EBVaGC by targeting DKK1.
Asunto(s)
Movimiento Celular/fisiología , Proliferación Celular/fisiología , Herpesvirus Humano 4/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , MicroARNs/genética , Western Blotting , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica/genética , Regulación Neoplásica de la Expresión Génica/fisiología , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , MicroARNs/metabolismo , Cicatrización de Heridas/genética , Cicatrización de Heridas/fisiologíaRESUMEN
Although Epstein-Barr virus (EBV) BamHI A rightward transcript (BART) microRNAs (miRNAs) are ubiquitously expressed in EBV-associated tumors, the role of most BART miRNAs is unclear. In this study, we showed that Bcl-2-associated death promoter (BAD) expression was significantly lower in EBV-infected AGS-EBV cells than in EBV-negative AGS cells and investigated whether BART miRNAs target BAD. Using bioinformatics analysis, five BART miRNAs showing seed match with the 3' untranslated region (3'-UTR) of BAD were selected. Of these, only miR-BART20-5p reduced BAD expression when individually transfected into AGS cells. A luciferase assay revealed that miR-BART20-5p directly targets BAD. The expression of BAD mRNA and protein was decreased by miR-BART20-5p and increased by an inhibitor of miR-BART20-5p. PE-Annexin V staining and cell proliferation assays showed that miR-BART20-5p reduced apoptosis and enhanced cell growth. Furthermore, miR-BART20-5p increased chemoresistance to 5-fluorouracil and docetaxel. Our data suggest that miR-BART20-5p contributes to tumorigenesis of EBV-associated gastric carcinoma by directly targeting the 3'-UTR of BAD.