[Expression and function of TRAF1 in Hodgkin's lymphoma cells.]

To investigate the function of tumor necrosis factor receptor-associated factor 1 (TRAF1) and CD30-TRAF1 signaling in Hodgkin's lymphoma.

Endogenous and CD30 ligand-induced TRAF1 expression at mRNA and protein levels were examined by quantitative RT-PCR and Western blot analyses, respectively. RNA interference was performed to silence the expression of TRAF1 in L428 cells and examine its effect on cell survival. ELISA-based NF-kappaB family transcription factor activity assay was performed to quantify the kappaB DNA-binding activity in nuclear extracts. The expression of JunB was measured by Western blot.

TRAF1 expression was detected at both mRNA and protein levels in B cell-derived lymphoma cell lines (L428 and KM-H2). CD30 activation via binding to CD30 ligand induced the TRAF1 expression, the relative mRNA expression was increased to 7.26 +/- 0.23 from 3.50 +/- 0.20, the relative protein expression was increased to 4.53 +/- 0.55 from 2.31 +/- 0.35. The apoptosis rate was increased to (27.7 +/- 5.8)% in TRAF1-silenced L428 cells compared to (5.7 +/- 1.2)% in control cells. The p50 and RelA DNA-binding activity were decreased in TRAF1-silenced L428 cells. The expression of JunB upon CD30 ligand stimulation was not changed in TRAF1-silenced L428 cells.

TRAF1 is overexpressed in B cell-derived Hodgkin's lymphoma cells, which is regulated by CD30 signaling pathway. TRAF1 is a crucial molecule mediating the activation of the classical NF-kappaB activity, which further facilitates the anti-apoptosis.