tetrathiomolybdate and Neuroblastoma

Neuroblastoma is the most common extracranial solid tumour of infancy. Pathological activation of glucose consumption, glycolysis and glycolysis-activating Akt kinase occur frequently in neuroblastoma cells, and these changes correlate with poor prognosis of patients. Therefore, several inhibitors of glucose utilization and the Akt kinase activity are in preclinical trials as potential anti-cancer drugs. However, metabolic plasticity of cancer cells might undermine efficacy of this approach. In this work, we identified oxidative phosphorylation as compensatory mechanism preserving viability of neuroblastoma cells with inhibited glucose uptake/Akt kinase. It was oxidative phosphorylation that maintained intracellular level of ATP and proliferative capacity of these cells. The oxidative phosphorylation inhibitors (rotenone, tetrathiomolybdate) synergized with inhibitor of the Akt kinase/glucose uptake in down-regulation of both viability of neuroblastoma cells and clonogenic potential of cells forming neuroblastoma spheroids. Interestingly, tetrathiomolybdate acted as highly specific inhibitor of oxygen consumption and activator of lactate production in neuroblastoma cells, but not in normal fibroblasts and neuronal cells. Moreover, the reducing effect of tetrathiomolybdate on cell viability and the level of ATP in the cells with inhibited Akt kinase/glucose uptake was also selective for neuroblastoma cells. Therefore, efficient elimination of neuroblastoma cells requires inhibition of both glucose uptake/Akt kinase and oxidative phosphorylation activities. The use of tetrathiomolybdate as a mitochondrial inhibitor contributes to selectivity of this combined treatment, preferentially targeting neuroblastoma cells.

Topics: Adenosine Triphosphate; Animals; Cell Line, Tumor; Cell Respiration; Down-Regulation; Fibroblasts; Glucose; Humans; Lactic Acid; Mice, Inbred C57BL; Mitochondria; Molybdenum; Neuroblastoma; Neurons; Oxidative Phosphorylation; Oxygen Consumption; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt

Growth of tumor cells depends on sufficient supply of fermentable substrate, such as glucose. This provokes development of new anticancer therapies based on dietary restrictions. However, some tumor cells can lower their glucose dependency and activate processes of ATP formation/saving to retain viability even in limited glucose supply. In addition, tumor cells often lose sensitivity to many conventional anticancer drugs in the low-glucose conditions. Thus, development of the drugs effectively killing the tumor cells in nutrient-limited conditions is necessary. In this study, we show an enhanced cytotoxicity of tetrathiomolybdate, the drug exhibiting antiangiogenic and tumor-suppressing effects, to neuroblastoma SH-SY5Y and SK-N-BE(2) cells in the low-glucose conditions. This preference results from the tetrathiomolybdate-induced upregulation of cell dependency on glucose. The cells treated with tetrathiomolybdate increase the uptake of glucose, production of lactate, activate the Akt- and AMPK-signaling pathways and downregulate COX IV. In cells growing in the low-glucose conditions, these events result in significant decrease of the intracellular ATP supply and apoptosis. We propose tetrathiomolybdate as suitable agent to be used in combination with dietary restrictions in therapy of neuroblastoma.

Topics: AMP-Activated Protein Kinases; Angiogenesis Inhibitors; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Down-Regulation; Glucose; Humans; Hypoxia; Molybdenum; Neuroblastoma; Proto-Oncogene Proteins c-akt; Signal Transduction; Tumor Microenvironment