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NF-κB Signaling Regulates Expression of Epstein-Barr Virus BART MicroRNAs and Long Noncoding RNAs in Nasopharyngeal Carcinoma
- Source :
- Journal of Virology
- Publication Year :
- 2016
- Publisher :
- American Society for Microbiology, 2016.
-
Abstract
- Epstein-Barr virus (EBV) expresses few viral proteins in nasopharyngeal carcinoma (NPC) but high levels of BamHI-A rightward transcripts (BARTs), which include long noncoding RNAs (lncRNAs) and BART microRNAs (miRNAs). It is hypothesized that the mechanism for regulation of BARTs may relate to EBV pathogenesis in NPC. We showed that nuclear factor-κB (NF-κB) activates the BART promoters and modulates the expression of BARTs in EBV-infected NPC cells but that introduction of mutations into the putative NF-κB binding sites abolished activation of BART promoters by NF-κB. Binding of p50 subunits to NF-κB sites in the BART promoters was confirmed in electrophoretic mobility shift assays (EMSA) and further demonstrated in vivo using chromatin immunoprecipitation (ChIP) analysis. Expression of BART miRNAs and lncRNAs correlated with NF-κB activity in EBV-infected epithelial cells, while treatment of EBV-harboring NPC C666-1 cells with aspirin (acetylsalicylic acid [ASA]) and the IκB kinase inhibitor PS-1145 inhibited NF-κB activity, resulting in downregulation of BART expression. Expression of EBV LMP1 activates BART promoters, whereas an LMP1 mutant which cannot induce NF-κB activation does not activate BART promoters, further supporting the idea that expression of BARTs is regulated by NF-κB signaling. Expression of LMP1 is tightly regulated in NPC cells, and this study confirmed that miR-BART5-5p downregulates LMP1 expression, suggesting a feedback loop between BART miRNA and LMP1-mediated NF-κB activation in the NPC setting. These findings provide new insights into the mechanism underlying the deregulation of BARTs in NPC and identify a regulatory loop through which BARTs support EBV latency in NPC. IMPORTANCE Nasopharyngeal carcinoma (NPC) cells are ubiquitously infected with Epstein-Barr virus (EBV). Notably, EBV expresses very few viral proteins in NPC cells, presumably to avoid triggering an immune response, but high levels of EBV BART miRNAs and lncRNAs which exhibit complex functions associated with EBV pathogenesis. The mechanism for regulation of BARTs is critical for understanding NPC oncogenesis. This study provides multiple lines of evidence to show that expression of BARTs is subject to regulation by NF-κB signaling. EBV LMP1 is a potent activator of NF-κB signaling, and we demonstrate that LMP1 can upregulate expression of BARTs through NF-κB signaling and that BART miRNAs are also able to downregulate LMP1 expression. It appears that aberrant NF-κB signaling and expression of BARTs form an autoregulatory loop for maintaining EBV latency in NPC cells. Further exploration of how targeting NF-κB signaling interrupts EBV latency in NPC cells may reveal new options for NPC treatment.
- Subjects :
- Gene Expression Regulation, Viral
0301 basic medicine
Epstein-Barr Virus Infections
Herpesvirus 4, Human
Immunology
Nasopharyngeal neoplasm
Biology
medicine.disease_cause
Microbiology
Viral Matrix Proteins
03 medical and health sciences
Virology
microRNA
Virus latency
Tumor Cells, Cultured
otorhinolaryngologic diseases
medicine
Humans
Spotlight
Promoter Regions, Genetic
Regulation of gene expression
Nasopharyngeal Carcinoma
Base Sequence
Deoxyribonuclease BamHI
Carcinoma
NF-kappa B
Nasopharyngeal Neoplasms
medicine.disease
Epstein–Barr virus
Virus Latency
Virus-Cell Interactions
MicroRNAs
stomatognathic diseases
030104 developmental biology
Nasopharyngeal carcinoma
Insect Science
Cancer research
RNA, Viral
RNA, Long Noncoding
Carcinogenesis
Chromatin immunoprecipitation
Signal Transduction
Subjects
Details
- ISSN :
- 10985514 and 0022538X
- Volume :
- 90
- Database :
- OpenAIRE
- Journal :
- Journal of Virology
- Accession number :
- edsair.doi.dedup.....293a04b6d6d9dd0d692fe6ad49e86396