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High-throughput sequence analysis of peripheral T-cell lymphomas indicates subtype specific viral gene expression patterns and immune cell microenvironments

ABSTRACT: Certain peripheral T-cell lymphomas (PTCLs) have been associated with viral infection, particularly infection with Epstein-Barr virus (EBV). However, a comprehensive virome analysis across PTCLs has not previously been reported, and viral gene expression profiles have been studied only in certain PTCL subtypes. In this study we utilized published RNA-seq data sets from seven different PTCL studies as well as new RNA-seq data from our laboratory to screen for virus association, to analyze viral gene expression, and to assess B- and T-cell receptor diversity paradigms across these tumor types. In addition to identifying EBV in angioimmunoblastic T-cell lymphoma (AITL) and extranodal NK/T cell lymphoma (ENKTL), two PTCL subtypes with well-established EBV associations, we also detected EBV in several cases of anaplastic large cell lymphoma (ALCL), and we found evidence of infection by the oncogenic viruses KSHV and HTLV-1 in isolated PTCL cases. In AITLs, EBV gene expression analysis showed expression of immediate early, early and late lytic genes, suggesting either abortive lytic replication and/or productive infection in a subset of the EBV infected infiltrating B-lymphocytes. Deconvolution of immune cell subpopulations demonstrated a greater B-cell signal in AITLs than in other PTCL subtypes, consistent with a larger role for B-cell support in the pathogenesis of AITL. T-cell receptor (TCR) and B-cell receptor (BCR) repertoires reconstructed from RNA-seq data demonstrated increased BCR diversity in AITLs, consistent with a possible EBV-driven polyclonal response. These findings indicate potential alternative roles for EBV in PTCLs in addition to the canonical oncogenic mechanisms associated with EBV latent infection. The findings also suggest the involvement of other viruses in T-cell lymphoma pathogenesis and demonstrate immunological alterations associated with these cancers.

ORGANISM(S): Homo sapiens

PROVIDER: GSE131261 | GEO | 2019/06/25

REPOSITORIES: GEO

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Project description:The Epstein-Barr virus (EBV) switches between latent and lytic phases in hosts that are important in developing related diseases. However, the underlying mechanism of how the viral latent-lytic switch is controlled and how EBV itself mediates this regulation remains largely unknown. This study identified the upregulated histone acetyl reader bromodomain-containing protein 7 (BRD7) during EBV latent infection. Based on the ChIP-sequencing of endogenous BRD7 in Burkitt lymphoma cells, we found that EBV drove BRD7 to regulate cellular and viral genomic loci, including the transcriptional activation of c-Myc, a recently reported regulator of EBV latency. Additionally, EBV-mediated BRD7 signals enriched around the FUSE site in chromosome 8, and the enhancer LOC108348026 in the lgH locus, which might activate the c-Myc alleles. Mechanically, EBV-encoded nuclear antigen 1 (EBNA1) bound and recruited BRD7 to colocalize at promotor regions of the related genes, thus serving as cofactors for the maintenance of viral latency. Moreover, the disruption of BRD7 decreased the c-Myc expression, induced the BZLF1 expression, and reactivated the lytic cycle. Our findings reveal the unique role of BRD7 hijacked by EBV in maintaining the viral latency state via chromatin remodeling. The study paved the way for understanding the new molecular mechanism of EBV-induced chromatin remodeling and latent-lytic switch regulation, providing novel therapeutic candidate targets for EBV persistent infection. With establishing persistent infection in most human hosts, EBV is usually at a latent infection state. How the viral latency is maintained in cells remains largely unknown. c-Myc was recently reported to act as a controller of the lytic switch, while whether and how EBV regulates it remains to be explored. Here, we identified that BRD7 is involved in controlling EBV latency. We found that EBV-mediated BRD7 was enriched in both the normal promoter regions and the translocation alleles of c-Myc, and the disruption of BRD7 decreased c-Myc expression to reactivate the lytic cycle. We also demonstrated that EBV-encoded EBNA1 bound to and regulated BRD7. Therefore, we reveal a novel mechanism by which EBV can regulate its infection state by hijacking host BRD7 to target c-Myc. Our findings will help future therapeutic intervention strategies of EBV infection and pathogenesis.

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High-throughput sequence analysis of peripheral T-cell lymphomas indicates subtype specific viral gene expression patterns and immune cell microenvironments

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