2-Deoxyglucose-induced toxicity is regulated by Bcl-2 family members and is enhanced by antagonizing Bcl-2 in lymphoma cell lines

Targeting altered cancer cell metabolism with the glycolysis inhibitor, 2-deoxyglucose (2DG), is a viable therapeutic strategy, but the effects of 2DG on lymphoma cells and the mechanism of action are unknown. Five T-cell lymphoma lines and two B-cell lymphoma lines were shown to be highly sensitive to 2DG. Examination of the cell death pathway demonstrated pro-apoptotic protein Bax 'activation' and caspase cleavage in 2DG-treated cells. However, Q-VD-OPh, a potent inhibitor of caspase activity provided minimal protection from death. In contrast, overexpressing the anti-apoptotic protein Bcl-2 dramatically enhanced the survival of 2DG-treated cells that was negated by a Bcl-2 antagonist. BH3-only members, Bim and Bmf, were upregulated by 2DG, and shRNAs targeting Bim protected from 2DG toxicity demonstrating that Bim is a critical mediator of 2DG toxicity. 2DG also induced GADD153/CHOP expression, a marker of endoplasmic reticulum (ER) stress and a known activator of Bim. Mannose, a reagent known to alleviate ER stress, transiently protected from 2DG-induced cell death. Examination of the effects of 2DG on energy metabolism showed a drop in ATP levels by 30 min that was not affected by either Bcl-2 or mannose. These results demonstrate that ER stress appears to be rate limiting in 2DG-induced cell death in lymphoma cells, and this cell killing is regulated by the Bcl-2 family of proteins. Bcl-2 inhibition combined with 2DG may be an effective therapeutic strategy for lymphoma.