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Inducible loss of NF-κB activity is associated with apoptosis and Bcl-2 down-regulation in Epstein-Barr virus-transformed B lymphocytes

2000; Elsevier BV; Volume: 95; Issue: 6 Linguagem: Inglês

10.1182/blood.v95.6.2068.2068

1528-0020

Jean Feuillard, Marino Schuhmacher, Sylvie Kohanna, Marianne Asso‐Bonnet, Frédérique Ledeur, Raymonde Joubert‐Caron, Philippe Bissières, Axel Polack, Georg W. Bornkamm, Martine Raphaël,

Immune Cell Function and Interaction

Abstract The Epstein–Barr virus (EBV)-encoded latent membrane protein-1 induces NF-κB activity by targeting IκBα. To understand the role of NF-κB activation in EBV-related oncogenesis, we have subcloned mutated IκBα32/36A cDNA into a pHEBo vector containing doxycycline regulatory sequences and stably transfected this construct into a lymphoblastoid cell line. Two tightly regulated clones were obtained in which IκBα32/36A was inducible in a doxycycline dose-dependent manner. Levels of inducible IκBα32/36A peaked at day 2. Inhibition of NF-κB activity was closely correlated with levels of inducible IκBα32/36A. Levels of 3 well-known NF-κB-dependent genes, CD54, p105, and endogenous IκBα, were decreased when IκBα32/36A was induced, and the growth of IκBα32/36A-induced EBV-infected cells was slightly reduced. Loss of NF-κB activity was associated with decreased Bcl-2 protein levels. Finally, the induction of apoptosis was strongly increased in IκBα32/36A-overexpressing cells. Together these results show that it is possible to control IκBα32/36A levels, ie, NF-κB activity, in EBV-infected B-lymphocytes using a doxycycline-inducible vector. Moreover, our results indicate that NF-κB can protect EBV-infected cells from apoptosis by Bcl-2. Finally, our results suggest that a cellular model with doxycycline-inducible IκBα32/36A may be useful in the identification of genuine NF-κB target genes in EBV-infected B cells.