Question

How does the rate of glucose catabolism in cancer tissues qualitatively and quantitatively compare to the rate of glucose catabolism in normal surrounding tissues?

-Please do not say it is just ten times faster than surrounding tissues

Answer 1

Answer: Cancer is a disease at the cellular level involving heritable disorders in the cellular control mechanism. The two most important biochemical phenotypes of cancer cell are an ability to maintain an increased rate of glucose utilization and the capacity to sustain high rates of glycolysis under aerobic conditions. The increased rate of glucose catabolism in case of cancer, when compared to the normal cell, is beneficial because cancer cell obtains over 50% of their energy and the anabolic precursors for biosynthetic pathways through glycolysis.

In comparison to the normal cell, cancerous cell poses a high activity of hexokinase, a key enzyme of glycolysis due to reasons. One is the overproduction of the enzyme and the other one is its binding to the outer mitochondrial membrane.

In the cancer cell, energy metabolism is altered which results in increased resting energy expenditure hence, associated with increased metabolism of sugar. Tumour growth and immune system activation are responsible for an increased energy usage and thus for continuous consumption of energetic substrates, such as glucose.

According to Carbtree, for normal cells, the presence of glucose has slightly increased respiration or had no effect on oxygen consumption whereas glucose decreased oxygen uptake by cancer cells.

In contrary to normal cells despite high energy requirement cancer cell uses primitive aerobic glycolysis and this biogenetic alteration is because of high demand to produce other metabolic end products to support their rapid growth and proliferation under low oxygen tension known as Warburg Phenomenon.