Oxidative stress is not required for the induction of apoptosis upon glutamine starvation of Sp2/0-Ag14 hybridoma cells

Abstract L-glutamine (Gln) withdrawal rapidly triggers apoptosis in the murine hybridoma cell line Sp2/0-Ag14 (Sp2/0). In this report, we examined the possibility that Gln deprivation of Sp2/0 cells triggers an oxidative stress which would contribute to the activation of apoptotic pathways. Gln withdrawal triggered an oxidative stress in Sp2/0 cells, as indicated by an increased accumulation of reactive oxygen species (ROS) and an increase in the intracellular content in protein carbonyl groups. Gln starvation also caused a decrease in the intracellular levels of glutathione (GSH). However, a decrease in GSH was not sufficient to induce Sp2/0 cell death since reducing GSH levels with DLbuthionine-[S,R]-sulfoximine did not affect cell viability. The antioxidant N-acetyl-L-cysteine (NAC), while effective in inhibiting ROS accumulation and oxidative stress, did not prevent the loss in cell viability or the processing and activation of caspase-3 triggered by Gln starvation. On the other hand, NAC did reduce the formation of apoptotic bodies in dying cells. Altogether these results indicate that in Sp2/0 cells, Gln deprivation leads to the induction of an oxidative stress which, while involved in the formation of apoptotic bodies, is not essential to the activation of the cell death program