Background: Rapidly growing cancer cells are often dependent on glycolysis for ATP production, known as the Warburg effect. The novel glycolysis inhibitor, 3-bromo-2-oxopropionate-1-propyl ester (3-BrOP), has shown efficacy in models of glioblastoma, colon carcinoma and lymphoma. Evidence suggests that acute lymphoblastic leukemias (ALL) are also dependent on glycolysis. We proposed that potent inhibition of glycolysis would induce growth arrest and cell death in ALL blasts. Furthermore, we hypothesized that anti-metabolic therapies (methotrexate and rapamycin) may synergize with the ATP depletion caused by inhibition of glycolysis.
Objective: To determine the effect of 3-BrOP on human precursor-B and T cell leukemias, and to evaluate combination therapy with methotrexate (MTX) and/or rapamycin.
Design/Methods: A panel of nine human pre-B ALL and T-ALL cell lines were treated with 3-BrOP to determine IC50 via cell counts, cell cycle and MTT analysis under conditions of hypoxia and normoxia. Subsequently combinations with methotrexate and rapamycin were evaluated.
Results: All pre-B ALL and T-ALL cell lines demonstrate growth arrest, decreased MTT metabolism and significant apoptosis when treated with 3-BrOP alone (IC50 10–30mcM) in both normoxia and hypoxia (0.5% 02). Indeed 40mcM 3-BrOP induced >90% death in all cell lines tested. Both pre-B ALL and T-ALL cell lines undergo enhanced apoptosis when 3-BrOP is combined with modest doses of methotrexate (7.5nM) or rapamycin (50nM), as compared to these agents alone. Specifically, at 72 hours exposure T-ALL MTT proliferation decreased from 20% with 3-BrOP alone to 1% with 3-BrOP + rapamycin (p=0.037). Furthermore, sub-G0 content increased from 44% with 3-BrOP alone to 75% with 3-BrOP + rapamycin (p=0.032). Similarly, at 48 hours of exposure, pre-B ALL cells had an increased sub-G0 content from 36% with 3-BrOP alone to 47% with 3-BrOP + rapamycin (p=0.025).
Conclusions: Inhibition of glycolysis via 3-BrOP induces growth arrest and apoptosis across a panel of human pre-B and T cell ALL cell lines indicating a generalized dependence on glycolysis. 3-BrOP is equally effective in both hypoxia and normoxia. When combined with methotrexate and/or rapamycin, 3-BrOP potentiates their anti-leukemia effects. These combinations offer promising therapeutic approaches in ALL and support further pre-clinical evaluation.
Disclosure:Financial Information: P Huang is a the patent holder.