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

Abstract

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 (TCLs) and two B cell lymphoma lines (BCLs) were shown to be highly sensitive to 2DG. Examination of the cell death pathway demonstrated proapoptotic 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 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 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.