Association of increased Bcl-2 expression with rescue from tumor necrosis factor-alpha-induced cell death in the oligodendrocyte cell line OLN-93

The present study investigated the effects of flupirtine (Katadolon) on tumor necrosis factor (TNF)-alpha -mediated cell death and Bcl-2 expression in the permanent rat oligodendrocyte cell line OLN-93 (OLN cells). TNF-alpha (500 U/ml) induced apoptosis of OLN cells, which was confirmed by DNA fragmentation using an in situ end-labeling technique and ultrastructural analysis. Flupirtine significantly reduced the rate of spontaneous cell death of OLN cells already at low concentrations; TNF-alpha -mediated apoptosis was suppressed only with higher concentrations of flupirtine (100 muM). Expression of Bcl-2 protein and mRNA in OLN cells was detected by immunocytochemistry, western blot, and RT-PCR. Quantitative analysis of western blots revealed an similar to2.5-fold upregulation of Bcl-2 protein during TNF-alpha treatment. Furthermore, addition of 10 or 100 muM flupirtine before incubation with TNF-alpha led to an approximately threefold increase of Bcl-2 expression. Exposure of OLN cells to flupirtine alone moderately augmented the expression of Bcl-2 protein. Our data demonstrate that flupirtine upregulates the expression of Bcl-2 protein in OLN cells; this Bcl-2 induction is associated with a reduced rate of TNF-alpha -induced cell death.