Suppression of the LMP2A target gene, EGR-1, protects Hodgkin's lymphoma cells from entry to the EBV lytic cycle
Hodgkin's lymphoma is unusual among B cell lymphomas, in so far as the malignant Hodgkin/Reed–Sternberg (HRS) cells lack a functional B cell receptor (BCR), as well as many of the required downstream signalling components. In Epstein–Barr virus (EBV)‐positive cases of Hodgkin's lymphoma, H...
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| Published in | The Journal of pathology Vol. 230; no. 4; pp. 399 - 409 |
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| Main Authors | , , , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
Chichester, UK
John Wiley & Sons, Ltd
01.08.2013
Wiley Subscription Services, Inc |
| Subjects | |
| Online Access | Get full text |
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| Summary: | Hodgkin's lymphoma is unusual among B cell lymphomas, in so far as the malignant Hodgkin/Reed–Sternberg (HRS) cells lack a functional B cell receptor (BCR), as well as many of the required downstream signalling components. In Epstein–Barr virus (EBV)‐positive cases of Hodgkin's lymphoma, HRS cells express the viral latent membrane proteins (LMP)‐1 and ‐2A. LMP2A is thought to contribute to the pathogenesis of Hodgkin's lymphoma by providing a surrogate BCR‐like survival signal. However, LMP2A has also been shown to induce the virus‐replicative cycle in B cells, an event presumably incompatible with lymphomagenesis. In an attempt to resolve this apparent paradox, we compared the transcriptional changes observed in primary HRS cells with those induced by LMP2A and by BCR activation in primary human germinal centre (GC) B cells, the presumed progenitors of HRS cells. We found a subset of genes that were up‐regulated by both LMP2A expression and BCR activation but which were down‐regulated in primary HRS cells. These genes included EGR1, an immediate‐early gene that is required for BCR‐induced entry to the virus‐replicative cycle. We present data supporting a model for the pathogenesis of EBV‐positive Hodgkin's lymphoma in which LMP2A‐expressing HRS cells lacking BCR signalling functions cannot induce EGR1 and are consequently protected from entry to the virus lytic cycle. The primary microarray data are available from GEO (http://www.ncbi.nlm.nih.gov/geo/) under series Accession No 46143. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. |
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| Bibliography: | istex:C8D76C2D5B93E49F4C79F519A961871A03F85666 ArticleID:PATH4198 Appendix S1. Supplementary materials and methodsPhenotype of enriched CD10+ germinal centre B cells. Flow-cytometric analysis of tonsillar mononuclear cells after enrichment for CD10. (A) Cells were stained for CD10 or CD19 together with CD24. (B) Cells were stained for CD10, CXCR4 and CD83. (C) Cells were stained for CXCR4 and CD77Expression of LMP2A in primary human germinal centre B cells. (A) Flow-cytometric analysis of CD10+ tonsillar B cells transfected with pSG5 (left) or LMP2A (right), together with pMACSLNGFR and stained for CD10 and NGFR prior to sorting (B) Detection of LMP2A and β-actin in transfected CD10+ tonsillar B cells by immunoblot analysis prior to sortingLMP2A and BCR activation regulate a common subset of target genes in primary human GC and BL2 cells. LMP2A target genes were compared with those genes shown to be differentially expressed in BCR crosslinked GC cells compared to unstimulated cells. (A) 323 genes were up-regulated by LMP2A in GC B cells and 1536 in stimulated GC B cells. Genes up-regulated following BCR activation were substantially enriched for those up-regulated by LMP2A [odds ratio (OR) = 16, p < 0.0001]. (B) 463 genes were down-regulated by LMP2A in GC B cells and 1572 in stimulated GC B cells. Genes down-regulated by BCR activation were enriched for those down-regulated by LMP2A (OR = 14.7, p < 0.0001). (C) qRT-PCR of the relative quantity of CCL3, CCL4, XBP1 and AID in LMP2A-expressing and control-transfected CD10+ GC B cells in two different tonsil samples (left panels), or following BCR crosslinking or CD40 stimulation in GC B cells (right panels). (D) Expression of these genes in LMP2A transfected BL2 cells. (E) Real-time RT-PCR of the relative quantity of STAT1, IFITM1, IFI6, HERC5 and CD80 in LMP2A-expressing and control-transfected CD10+ GC B cells in two different tonsil samplesLMP2A expression does not induces activation of the transcription factor Elk-1 in L1236 HL cells. L1236 cells were transfected with pSG5, pSG5-LMP2A or pFC-MEKK1 together with pFA-Elk1 and pFR-Luc. Relative luciferase activity was determined 24 h post-transfection. The results are the mean of three independent experiments (± SD)Overlap between transcriptional targets of LMP1, LMP2A, BCR crosslink and primary HRS cells compared to centrocytes. LMP2A and BCR target genes were compared with those genes shown to be differentially expressed in HRS cells compared to centrocytes and LMP1-expressing GC B cells. (A) 258 genes were up-regulated by LMP2A and BCR crosslink in GC B cells and 172 by LMP1 and in HRS cells compared to centrocytes. (B) 235 genes were down-regulated by LMP2A and BCR crosslink in GC B cells and 537 by LMP1 and in HRS cells compared to centrocytesGenes significantly up- or down- regulated by LMP2A in GC B cells with fold change > 1.3 and p value < 0.01.Genes significantly up- or down- regulated by BCR in GC B cells with fold change > 1.3 and p value < 0.01.List of genes that are concordantly regulated by LMP2A and BCR in GC B cells. ark:/67375/WNG-SJBR7821-7 No conflicts of interest were declared. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
| ISSN: | 0022-3417 1096-9896 |
| DOI: | 10.1002/path.4198 |