According to the cancer stem cell (CSC) hypothesis, the aggressive growth and early
metastasis of pancreatic ductal
adenocarcinoma (PDA) is due to the activity of CSCs, which are not targeted by current
therapies. Otto Warburg suggested that the growth of
cancer cells is driven by a high
glucose metabolism. Here, we investigated whether glycolysis inhibition targets CSCs and thus may enhance therapeutic efficacy. Four established and 3 primary PDA cell lines, non-malignant cells, and 3 patient-
tumor-derived CSC-enriched spheroidal cultures were analyzed by
glucose turnover measurements, MTT and
ATP assays, flow cytometry of ALDH1 activity and
annexin positivity, colony and spheroid formation, western blotting, electrophoretic mobility shift assay,
xenotransplantation, and immunohistochemistry. The effect of
siRNA-mediated inhibition of
LDH-A and
LDH-B was also investigated. The PDA cells exhibited a high
glucose metabolism, and
glucose withdrawal or LDH inhibition by
siRNA prevented growth and colony formation. Treatment with the anti-glycolytic agent
3-bromopyruvate almost completely blocked cell viability, self-renewal potential, NF-κB binding activity, and stem cell-related signaling and reverted
gemcitabine resistance.
3-bromopyruvate was less effective in weakly malignant PDA cells and did not affect non-malignant cells, predicting minimal side effects.
3-bromopyruvate inhibited in vivo
tumor engraftment and growth on chicken eggs and mice and enhanced the efficacy of
gemcitabine by influencing the expression of markers of proliferation, apoptosis, self-renewal, and
metastasis. Most importantly, primary CSC-enriched spheroidal cultures were eliminated by
3-bromopyruvate. These findings propose that CSCs may be specifically dependent on a high
glucose turnover and suggest
3-bromopyruvate for therapeutic intervention.