CD40-induced growth inhibition in epithelial cells is mimicked by Epstein-Barr Virus-encoded LMP1: involvement of TRAF3 as a common mediator - PubMed (original) (raw)

. 1996 Nov 21;13(10):2243-54.

C W Dawson, G Mosialos, J E Floettmann, M Rowe, R J Armitage, J Dawson, J M Zapata, D J Kerr, M J Wakelam, J C Reed, E Kieff, L S Young

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CD40-induced growth inhibition in epithelial cells is mimicked by Epstein-Barr Virus-encoded LMP1: involvement of TRAF3 as a common mediator

A G Eliopoulos et al. Oncogene. 1996.

Abstract

CD40, a member of the tumour necrosis factor receptor family, is expressed on the surface of B lymphocytes where its ligation provides a potent survival signal. CD40 is also expressed in basal epithelial cells and in a number of different carcinomas where its function remains unknown. We observed that contrary to the studies in normal B cells, CD40 ligation in carcinoma cell lines and in normal primary epithelial cells resulted in growth inhibition and enhanced susceptibility to apoptosis induced by anti-neoplastic drugs, TNF-alpha, Fas and ceramide. This effect was also observed in CD40-transfected Rat-1 fibroblasts. The expression of Bcl-2 did not affect growth inhibition induced by CD40 ligation in epithelial cells but the Epstein - Barr Virus-encoded latent membrane protein 1 (LMP1) blocked the effect. Whilst transient expression of LMP-1 resulted in the inhibition of epithelial cell growth, this effect was not observed with a LMP1 mutant lacking the binding domain for TRAF3, a protein which may mediate signal transduction by interacting with the cytoplasmic domains of both CD40 and LMP1. Transient expression of TRAF3 also inhibited epithelial cell growth, whilst expression of a dominant-negative TRAF3 partially blocked the inhibitory effect of CD40 ligation and of transient LMP1 expression. These results suggest that CD40 regulates epithelial cell growth in a manner mimicked by LMP1 and implicate TRAF3 as a common mediator in the transduction of the growth inhibitory signals generated via the CD40 and LMP1 pathways.

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