2-Deoxy-D-glucose induces Type II cell death in pancreatic cancer.

B35

Inhibition of glycolytic pathway is becoming an important strategy in cancer therapeutics for targeting a major survival pathway in hypoxic cancers solely dependent on glucose as an energy source. 2-Deoxy-D-glucose (2-DG) has been shown to be a potent inhibitor of glycolysis in glioma cancer cells which depend almost exclusively on glucose for metabolism. Here we investigated the effect of 2-DG as an inhibitor of cell growth in a panel of pancreatic cancer cell lines including MiaPaCa2 and Panc1. To asses the cytotoxicity of 2-DG, MiaPaCa2 and Panc1 cells were treated with increasing concentrations of 2-DG for 24, 48 and 72 hour periods under normoxic (21% O₂) and hypoxic (0.1% O₂) conditions. The results from MiaPaCa2 treated cells revealed the IC50 (2-DG) to be 2.3 mM and that sensitivity of the MiaPaCa2 cells towards 2-DG increases by 37% under hypoxic conditions. When MiaPaCa2 cells were grown under same conditions in low glucose media (5.6 mM), sensitivity of MiaPaCa2 cells to 2-DG treatment further increased 82%, however the use of low glucose media under hypoxic conditions did not further increase the sensitivity of MiaPaCa2 cells to 2-DG. 2-DG cytotoxicity studies in Panc1 treated cells demonstrated a 3 fold higher resistance to 2-DG treatment (IC50 6.9 mM) than observed in the MiaPaCa2 cell line suggesting sensitivity to the monosaccharide based antimetabolites like 2-DG is cell specific as demonstrated by increased activity in the highly glycolytic MiaPaCa2 cell line. We also assessed the induction of autophagy in MiaPaCa2 cells using acridine orange staining to determine the acidic vesicular organelles (AVO), a hallmark of autophapy cell death. Here we found supporting evidence of 2-DG as an inducer of autophagic cell death, showing a significant increase in AVOs following treatment with 5 mM 2-DG. These findings support our hypothesis that 2-DG acts as a potent inhibitor of cell proliferation in MiaPaca2 pancreatic cancer cell line, and is not as potent in cell lines less dependent on glycolysis like the Panc1 cell line. These data in total provide strong evidence that inhibitors of the glycolytic pathway could be a significant therapeutic strategy in the treatment of pancreatic and other highly glycolysis- dependent tumor types.