Latency expression of the Epstein-Barr virus-encoded MHC class I TAP inhibitor, BNLF2a in EBV-positive gastric carcinomas
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE70513 | GEO | 2015/07/16
SECONDARY ACCESSION(S): PRJNA288939
REPOSITORIES: GEO
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Project description:The Epstein-Barr virus (EBV) BNLF2a gene product provides immune evasion properties to infected cells through inhibition of transporter associated with antigen processing (TAP)-mediated transport of antigen peptides. Although BNLF2a is considered to be a lytic gene, we demonstrate that it is expressed in nearly half of the EBV-associated gastric carcinomas analyzed. Further, we show that BNLF2a expression is dissociated from lytic gene expression. BNLF2a is therefore expressed in this latency setting, potentially helping protect the infected tumor cells from immunosurveillance.
| S-EPMC4577887 | biostudies-literature
Project description:This study compares cellular and viral gene expression in a cord blood-humanized (CBH) mouse model infected with wild-type Epstein-Barr virus (WT), versus a mutant EBV deleted in the latent viral EBNA3C gene (∆3C). EBV causes human B-cell lymphomas and transforms B cells in vitro. EBNA3C, an EBV protein expressed in latently infected cells, is required for EBV transformation of B cells in vitro. However, many EBV+ lymphomas in humans do not express this protein, suggesting that it may be less important in vivo or that cellular mutations and/or signaling pathways may obviate the need for EBNA3C. EBNA3C collaborates with EBNA3A to repress expression of the CDKN2A-encoded tumor suppressors, p16 and p14, and EBNA3C-deleted EBV transforms B cells containing a p16 germline mutation in vitro. We found that the ∆3C virus induced fewer lymphomas (occurring with a delayed onset) in comparison to the wild-type (WT) control virus, although a subset (10/26) of Δ3C-infected CBH mice eventually developed invasive diffuse large B cell lymphomas with type III latency. Both WT and ∆3C viruses induced monoclonal B-cell lymphomas (without somatic hyper-mutation) that were infiltrated by polyclonal T cells. In comparison to WT-infected tumors, ∆3C-infected tumors had greatly increased p16 levels, and RNA-seq analysis revealed a decrease in E2F target gene expression. However, we found that ∆3C-infected tumors expressed c-Myc and cyclin E at similar levels compared to WT-infected tumors, allowing cells to at least partially bypass p16-mediated cell cycle inhibition. Unexpectedly, ∆3C-infected tumors had increased T-cell infiltration, increased expression of T-cell chemokines (CCL5, CCL20 and CCL22) and enhanced type I interferon response in comparison to WT tumors. Together, these results reveal that EBNA3C contributes to, but is not essential for, EBV-induced lymphomagenesis in CBH mice, and suggest potentially important immunologic roles of EBNA3C in vivo.
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Project description:The Epstein-Barr virus (EBV) is associated with lymphoid and epithelial cancers. Initial EBV infection alters lymphocyte gene expression, inducing cellular proliferation and differentiation as the virus transitions through consecutive latency transcription programs. Cellular microRNAs (miRNAs) are important regulators of signaling pathways and are implicated in carcinogenesis. The extent to which EBV exploits cellular miRNAs is unknown. Using micro-array analysis and quantitative PCR, we demonstrate differential expression of cellular miRNAs in type III versus type I EBV latency including elevated expression of miR-21, miR-23a, miR-24, miR-27a, miR-34a, miR-146a and b, and miR-155. In contrast, miR-28 expression was found to be lower in type III latency. The EBV-mediated regulation of cellular miRNAs may contribute to EBV signaling and associated cancers.
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2024-04-17 | GSE252480 | GEO
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