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J Virol. 2009 Mar;83(6):2491-9. doi: 10.1128/JVI.01681-08. Epub 2009 Jan 14.

MDM2-dependent inhibition of p53 is required for Epstein-Barr virus B-cell growth transformation and infected-cell survival.

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1
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.

Abstract

Epstein-Barr virus (EBV) growth transformation of primary B lymphocytes into indefinitely proliferating lymphoblastoid cell lines (LCLs) depends on the concerted activities of a subset of viral proteins expressed during latency. EBV drives quiescent B cells into S phase, and consequently, a host response is activated that includes expression of p53 and its target genes. Since LCLs retain wild-type p53, it was of interest to determine what contribution the p53 pathway may have in controlling established LCL growth and EBV-mediated transformation of primary B cells. We found that liberation of p53 through chemical antagonism of one of its major ubiquitin ligases, MDM2, using the small-molecule Nutlin-3 led to apoptosis of established LCLs and suppressed EBV-mediated transformation of primary B cells. The activation of latent p53 induced target genes associated with apoptosis. Furthermore, MDM2 antagonism synergized with NF-kappaB inhibition in killing LCLs. NF-kappaB was important to increase steady-state MDM2 protein levels rather than in affecting p53-dependent transcription, suggesting a unique mechanism by which LCLs survive in the presence of a primed p53 pathway. Nutlin sensitivity of EBV-infected cells provides a novel system for studying the pathways that dictate LCL survival and regulate EBV transformation. Finally, MDM2 antagonists may be considered for therapeutic intervention in EBV-associated malignancies expressing wild-type p53.

PMID:
19144715
PMCID:
PMC2648290
DOI:
10.1128/JVI.01681-08
[Indexed for MEDLINE]
Free PMC Article
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