Abstract LB-250: 2-Deoxy-D-glucose cytotoxicity relies on both glycolysis inhibition and ER stress induction, and is efficacious in a variety of human lymphoma models

Introduction: 2-Deoxy-D-glucose (2DG) is a glucose analogue reported to be efficacious in a variety of cancers. Its mechanism of cytotoxicity has been proposed to lie in its inhibition of glycolysis as well as interfering with N-linked glycosylation, which results in protein misfolding and activation of the ER stress response. Previous work indicates that ER stress induction is important in 2DG toxicity. However, these studies do not clarify the relative role of glycolysis inhibition in its toxicity. In addition, little is known about the efficacy of 2DG in human lymphoma. Materials and Methods: Eight human lymphoma lines, murine B cell lymphoma lines and peripheral blood samples of patients with chronic lymphocytic leukemia (CLL) were utilized in these studies. Q-PCR was used to measure CHOP induction by 2DG as a standard marker of ER stress. Four halogenated derivatives of 2DG as well as oxamate, a known glycolysis inhibitor, and tunicamycin, a known inhibitor of N-linked glycosylation, were used to isolate and study the individual mechanisms (glycolysis vs. N-linked glycosylation inhibition) of 2DG activity. Mannose was also used in co-treatment with these drugs as it overcomes the inhibition of N-linked glycosylation caused by these agents. Results and Conclusions: We found that a variety of human lymphoma cell lines and CLL samples exhibited varying degrees of sensitivity to 2DG. The human cell lines showed a 4-12 fold elevation of CHOP RNA following 24 hrs of 2DG treatment, with the sensitive lines showing an even larger increase in CHOP mRNA levels when compared to the resistant lines. Consistent with an important role of ER stress in 2DG toxicity, mannose protected against 2DG treatment. CLL patient samples showed significant cell death caused by 2DG but only at extended time points (6 days), which is consistent with the fact that CLL cells are slowly dividing with low metabolism. Two of the halogenated 2DG derivatives, 2-chloro or 2-bromo-2-deoxy-D-mannose were not toxic, did not inhibit ATP levels or activate ER stress in any of the cells. In contrast, 2-chloro or 2-bromo-2-deoxy-D-glucose showed intermediate toxicity, reduction in ATP levels, but did not significantly upregulate CHOP. This indicates the halogenated glucose derivatives inhibit glycolysis similar to 2DG but do not activate ER stress. Consistent with this conclusion, mannose did not protect cells from treatment with these derivatives. Combining these glucose derivatives with tunicamycin, an inducer of ER stress, showed cooperative activity in cell killing. Similarly, oxamate alone showed minimal toxicity but cooperated with tunicamycin in causing cell death. In summary, our results suggest that 2DG is uniquely effective because it inhibits two critical biochemical pathways - both of which appear to contribute to its cytotoxic activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-250. doi:1538-7445.AM2012-LB-250