Tumor cells can survive the hypoxia in the center of tumor masses by using glycolysis, rather than oxidative phosphorylation, to generate energy. Most tumor cells also stick to glycolysis when normally oxygenated. Valeria Fantin, Julie St-Pierre, and Philip Leder (Harvard Medical School, Boston, MA) now report that some tumor cells, despite their preference for glycolysis, nevertheless retain the ability to use oxidative phosphorylation.
The Boston team reached this conclusion by inhibiting lactate dehydrogenase A (LDH-A). This enzyme converts NADH and pyruvate, the products of glycolysis, into lactate and NAD+. The lactate is exported and the NAD+ used to keep glycolysis going.
Therefore, when LDH-A is shut off and oxygen is limited, NAD+ runs low and glycolysis alone cannot continue. When oxygen is around, however, the pyruvate can be converted to acetyl-CoA to feed the Krebs cycle, which in turn feeds oxidative...
