Question

1. Describe the metabolic phenotype known as the “Warburg Effect”, and comment on how it led Otto Warburg to incorrectly conclude that mitochondrial respiration was damaged in cancer cells. What evidence/data suggests he was wrong? (short paragraph)

Answer 1

Warburg effect is the phenomenon observed in the cancer cells. The aerobic glycolysis favoring the oxidative phosphorylation is absent. The glycolytic pathway is deviated to lactic acid production despite the presence of oxygen. Warburg effect is the phenomenon observed in the cancer cells. The aerobic glycolysis favoring the oxidative phosphorylation is absent. The glycolytic pathway is deviated to lactic acid production despite the presence of oxygen.

In 1920, Otto Warburg demonstrated this phenomenon in tumor tissues that the cultured cells had high glucose uptake, lactate production despite provision of oxygen supply. It was Louis Pasteur who defined this effect in sugar fermentation was suppressed in the presence of oxygen. Applying this concept to the tumor cells the oxygen supply must be cut off and an unnoticed hypoxia must be present in them. However, this is not true. Cancer cells are actively multiplying tissues and breathe oxygen.

The reason for Warburg effect is still not clear in cancer cells. One hypothesis that could be the reason for Warburg effect is that glucose uptake is used for the benefit of the cancer cells via pentose phosphate pathway. In theory the high lactate is absolutely inhibiting the carbon availability for cell proliferation in cancer cells. However, there will be ample intermediates of glucose intermediates. Warburg presented as a mitochondrial flaw which was disproved by his own experiments demonstrating that there was constant supply of oxygen. Mitochondrial activity is the only source for using oxygen. In fact reducing the supply of oxygen is deleterious and impacts cell proliferation negatively.