The B-Cell Specific Transcription Factor, Oct-2, Promotes Epstein-Barr Virus Latency by Inhibiting the Viral Immediate-Early Protein, BZLF1

The Epstein-Barr virus (EBV) latent-lytic switch is mediated by the BZLF1 immediate-early protein. EBV is normally latent in memory B cells, but cellular factors which promote viral latency specifically in B cells have not been identified. In this report, we demonstrate that the B-cell specific transcription factor, Oct-2, inhibits the function of the viral immediate-early protein, BZLF1, and prevents lytic viral reactivation. Co-transfected Oct-2 reduces the ability of BZLF1 to activate lytic gene expression in two different latently infected nasopharyngeal carcinoma cell lines. Furthermore, Oct-2 inhibits BZLF1 activation of lytic EBV promoters in reporter gene assays, and attenuates BZLF1 binding to lytic viral promoters in vivo. Oct-2 interacts directly with BZLF1, and this interaction requires the DNA-binding/dimerization domain of BZLF1 and the POU domain of Oct-2. An Oct-2 mutant (Δ262–302) deficient for interaction with BZLF1 is unable to inhibit BZLF1-mediated lytic reactivation. However, an Oct-2 mutant defective for DNA-binding (Q221A) retains the ability to inhibit BZLF1 transcriptional effects and DNA-binding. Importantly, shRNA-mediated knockdown of endogenous Oct-2 expression in several EBV-positive Burkitt lymphoma and lymphoblastoid cell lines increases the level of lytic EBV gene expression, while decreasing EBNA1 expression. Moreover, treatments which induce EBV lytic reactivation, such as anti-IgG cross-linking and chemical inducers, also decrease the level of Oct-2 protein expression at the transcriptional level. We conclude that Oct-2 potentiates establishment of EBV latency in B cells

dUTPase in human neoplastic cells as a potential target for therapeutic intervention

With the exception of brain, most human tissues analysed contain dUTPase protein detectable by immunohistochemistry. Non-dividing tissues like untreated peripheral blood lymphocytes (PBL's) contain basal levels of cytoplasmic dUTPase and express additional, nuclear dUTPase upon mitogenic stimulation. Normal, proliferating tissues like intestinal mucosa or germinal centres within tonsils contain cytoplasmic as well as nuclear dUTPase in accordance with a proposed role for dUTPase during cell division. Notably, no dUTPase is detectable during mitosis. The failure to stain dUTPase in normal brain tissue by immunohistochemistry while mRNA is readily detectable by Northern blotting cannot be explained at this moment. Epithelial tumours, such as adenocarcinoma of the lung, breast, colon, vulva or nasopharynx contain cells which are either positive for both or only one of the subcellular forms of the dUTPase and show variable numbers of dUTPase-positive cells. High levels of dUTPase correlate with a poor prognosis regarding the progression of colorectal carcinoma. Of the intracranial tumours tested, neuroepithelial tumours show almost exclusively nuclear expression whereas meningiomas of higher grades of malignancy (WHO grade II and III) also contain cells with additional cytoplasmic dUTPase. The dUTPase is detectable in other malignancies including tumours derived from lymphatic tissues like Burkitt's lymphoma or non-Hodgkin's-lymphoma. The downregulation of dUTPase protein during apoptosis or the inhibition of dUTPase during nerve cell development in Drosophila melanogaster suggests a possible role of the enzyme during apoptosis. In line with these observations, inhibition of dUTPase by antisense in p53-deficient tumour cells hints at a possible route of treatment of p53-deficient tumours which are otherwise resistant to therapies like irradiation. The expression of the enzyme in normal tissues indicates that sublethal levels of dUTPase inhibitors may also exert an unwanted mutagenic effect.link_to_subscribed_fulltex

Detection of wild type and deleted latent membrane protein 1 (LMP1) of Epstein-Barr virus in clinical biopsy material

The latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) is one of two postulated viral oncogenic proteins. Sequence variations, and in particular a 30 base pair deletion variant called CAO, may define different disease populations. We developed a panel of rat monoclonal antibodies (MAb) specific for the non-wild type LMP1 and compared the presence of the antibody staining with LMP1 DNA sequence analysis on clinical samples of nasopharyngeal carcinoma, peripheral T-cell lymphoma (PTCL), Hodgkin's disease, lymphoblastoid cell lines (LCL) from normal volunteers, and patients with nasopharyngeal carcinoma. The results demonstrate specificity of the monoclonal cocktail for detecting the non-wild type LMP1 and the ability to sub-differentiate between the mediterranean type of LMP1 and the CAO-LMP1. Double immunofluorescence on paraffin material using the traditional CS1-4 monoclonal antibodies and the CAO-cocktail revealed no dual population of cells in the biopsy material from the Asian region. © 2003 Elsevier B.V. All rights reserved.link_to_subscribed_fulltex

Polymorphisms and haplotypes in TLR9 and MYD88 are associated with the development of Hodgkin's lymphoma: a candidate-gene association study

Toll-like receptors (TLRs) and myeloid differentiation primary response protein 88 (MYD88) gene polymorphisms may be involved in the pathogenesis of Hodgkin's lymphoma (HL) through altered immunoregulatory and inflammatory responses. A candidate-gene association study was conducted to investigate the association between TLR9 -1237T > C, TLR9 2848A > G, MYD88 -938C > A and MYD88 1944C > G gene polymorphisms and the risk for HL. The impact of haplotypes was also examined. The study showed that carriership for -1237C and 2848A was associated with an increased risk for HL (odds ratio (OR)=2.53 (1.36-4.71) and OR=6.20 (1.3-28.8)). The MYD88 polymorphisms produced nonsignificant results. The estimated frequencies of the TLR9/1237C-2848A and MYD88/938C-1944G haplotypes were also significantly different between HL and controls (P < 0.01). In addition, a significant difference between HL and controls was observed for the TLR9/1237C-TLR9/2848A-MYD88/938C-MYD88/1944C haplotypes (P < 0.01). In conclusion, our study showed that TLR polymorphisms, and TLR9 and MYD88 haplotypes are related to the development of HL. Journal of Human Genetics (2009) 54, 655 - 659; doi:10.1038/jhg.2009.90; published online 11 September 200

MYB-QKI rearrangements in Angiocentric Glioma drive tumorigenicity through a tripartite mechanism

Angiocentric gliomas are pediatric low-grade gliomas (PLGGs) without known recurrent genetic drivers. We performed genomic analysis of new and published data from 249 PLGGs including 19 Angiocentric Gliomas. We identified MYB-QKI fusions as a specific and single candidate driver event in Angiocentric Gliomas. In vitro and in vivo functional studies show MYB-QKI rearrangements promote tumorigenesis through three mechanisms: MYB activation by truncation, enhancer translocation driving aberrant MYB-QKI expression, and hemizygous loss of the tumor suppressor QKI. This represents the first example of a single driver rearrangement simultaneously transforming cells via three genetic and epigenetic mechanisms in a tumor