Because the p300/CBP-mediated hyperacetylation of RelA (p65) is critical for nuclear factor-KB (NF-KB) activation, the attenuation of p65 acetylation is a potential molecular target for the prevention of chronic inflammation. During our ongoing screening study to identify natural compounds with histone acetyltransferase inhibitor (HATi) activity, we identified epigallocatechin-3-gallate (EGCG) as a novel HATi with global specificity for the majority of HAT enzymes but with no activity toward epigenetic enzymes including HDAC, SIRT1, and HMTase. At a dose of 100 Mmol/L, EGCG abrogates p300-induced p65 acetylation in vitro and in vivo, increases the level of cytosolic IKBA, and suppresses tumor necrosis factor A (TNFA)-induced NF-KB activation. We also showed that EGCG prevents TNFA-induced p65 translocation to the nucleus, confirming that hyperacetylation is critical for NF-KB translocation as well as activity. Furthermore, EGCG treatment inhibited the acetylation of p65 and the expression of NF-KB target genes in response to diverse stimuli. Finally, EGCG reduced the binding of p300 to the promoter region of interleukin-6 gene with an increased recruitment of HDAC3, which highlights the importance of the balance between HATs and histone deacetylases in the NF-KB-mediated inflammatory signaling pathway. Importantly, EGCG at 50 Mmol/L dose completely blocks EBV infection-induced cytokine expression and subsequently the EBV-induced B lymphocyte transformation. These results show the crucial role of acetylation in the development of inflammatory-related diseases. [Cancer Res 2009;69(2):583-92]

Epstein-Barr virus (EBV) latency gene expression in lymphoblastoid cell lines is regulated by EBNA2.However, the factors regulating viral expression in EBV-associated tumors that do not express EBNA2 are poorly understood. In EBV-associated tumors, EBNA1 and frequently LMP1 are synthesized. We found that an alternative latent membrane protein 1 (LMP1) promoter, L1-TR, located within the terminal repeats is active in both nasopharyngeal carcinoma and Hodgkin's disease tissues. Examination of the L1-TR and the standard ED-L1 LMP1 promoters in electrophoretic mobility shift assays revealed that both promoters contain functional STAT binding sites. Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that, after primary exposure, maintains a latent infection for the life of the individual. Approximately 1 to 50 per 10 6 circulating B cells in healthy seropositive individuals carry the EBV genome, and the site of long-term latency has been identified as the G 0 memory B cell (39). EBV infection elicits a strong immune response (44), and in general viral persistence is controlled by the host and is asymptomatic. However, one consequence of lifelong infection is the potential for the development of EBV-associated malignancies, which include Burkitt's lymphoma, nasopharyngeal carcinoma (NPC), Hodgkin's disease, lymphoproliferative disease in immunocompromised patients, primary central nervous system lymphoma in AIDS patients, nasal T-cell lymphoma, a subset of gastric carcinoma, and possibly also a subset of primary liver and breast cancers (2, 3, 43, 51).On initial EBV infection, and in latently infected lymphoblastoid cell lines in culture, the full spectrum of EBV latency genes is expressed. The Wp promoter, which is regulated by B-cell-specific factors, is responsible for the initial transcription of the nuclear EBNAs, EBNA1, EBNA2, EBNA3A, EBNA3B, EBNA3C, and EBNA-LP (32). EBNA2, which functions as a transcriptional activator, then enforces a switch to Cp promoter-driven EBNA synthesis and also regulates synthesis of the LMP1 and LMP2 latency membrane proteins. However, EBNA2 is detected in EBV-associated malignancies only in the context of immunosuppression, presumably because the Cp-driven EBNA3 family proteins elicit a robust CD8 cell-mediated immune response (44). In EBV-associated tumors in immunocompetent patients, the Cp is repressed by methylation (1, 41). An alternative TATA-less promoter, Qp (40,46), is used to express EBNA1 in the absence of the immunogenic EBNAs, and LMP1 is also frequently expressed. EBNA1 binds to the origin of latent DNA replication, oriP, and is required for maintainance of the episomal form of the latent EBV genome (35,42,60). LMP1, an integral membrane protein, is essential for EBV-driven B-cell immortalization and induces transformation in primary Rat1 cells (56). The transforming ability of LMP1 is explicable in large part by its functioning as a constituitively activated tumor necrosis factor (TNF) receptor that mimics signaling by the B-lymphocyte activation antigen CD4...

Epstein-Barr virus (EBV) infection of primary B cells causes B-

This study sought to explore the role of the IFN-related innate immune responses (IFN-b and IFN-l) and of reactive oxygen species (ROS) after influenza A virus (IAV) infection for antiviral innate immune activity in normal human nasal epithelial (NHNE) cells that are highly exposed to IAV. Passage-2 NHNE cells were inoculated with the IAV WSN/33 for 1, 2, and 3 days to assess the capacity of IFN and the relationship between ROS generation and IFN-l secretion for controlling IAV infection. Viral titers and IAV mRNA levels increased after infection. In concert with viral titers, we found that the generation of IFNs, such as IFN-b, IFN-l1, and IFN-l2/3, was induced after IAV infection until 3 days after infection. The induction of IFN-l gene expression and protein secretion may be predominant after IAV infection. Similarly, we observed that intracellular ROS generation increased 60 minutes after IAV infection. Viral titers and mRNA levels of IAV were significantly higher in cases with scavenging ROS, in cases with an induced IFN-l mRNA level, or where the secreted protein concentration of IFN-l was attenuated after the suppression of ROS generation. Both mitochondrial and dual oxidase (Doux)2-generated ROS were correlated with IAV mRNA and viral titers. The inhibition of mitochondrial ROS generation and the knockdown of Duox2 gene expression highly increased IAV viral titers and decreased IFN-l secretion. Our findings suggest that the production of ROS may be responsible for IFN-l secretion to control IAV infection. Both mitochondria and Duox2 are possible sources of ROS generation, which is required to initiate an innate immune response in NHNE cells.

Epstein-Barr virus (EBV)is associated with about 6 to 16% of gastric carcinoma cases worldwide. Expression of the EBV microRNAs (miRNAs) was observed in B cells and nasopharyngeal carcinoma cells infected with EBV. However, it is not clear if the EBV miRNAs are expressed in EBV-associated gastric carcinomas (EBVaGCs). We found that BART miRNAs but not BHRF1 miRNAs were expressed in EBV-infected gastric carcinoma cell lines and the tumor tissues from patients as well as the animal model. The expression of viral miRNAs in EBVaGCs suggests that these EBV miRNAs may play important roles in the tumorigenesis of EBVaGCs.