When cancer cells are using glutamine as main nutrient, how this means producing huge amount of ATPs? and If cancer cells used glutamine for energy production, is that energy production is going to be higher than the energy produced from using glucouse as main nutrient (i.e higher than 36 ATPs)?
Energy efficacy of glutaminolysis in tumor cells are defined as follows;
1 one ATP by direct phosphorylation of GDP
2 two ATP from oxidation of FADH2
3 three ATP at a time for the NADH + H+ produced within the α-ketoglutarate dehydrogenase reaction, the malate dehydrogenase reaction and the malate decarboxylase reaction.
http://jeccr.biomedcentral.com/articles/10.1186/s13046-015-0221-y
Article Metabolic reprogramming: The emerging concept and associated...
The energy production from glutamine is lower than that achieved from glucose if you consider that glucose enters into the OX-PHOS pathway (36 to 38 ATP produced). But we should keep in mind that glucose metabolism is reprogrammed in cancer. So, that usually glucose follows the aerobic glycolysis pathway (Warburg effect). In this case, only 2 ATPs are produced from each glucose molecule. As Warburg demonstrated in ascitic cancer cells, only 45% of glucose followed the OX-PHOS pathway and 55% went on with the aerobic glycolisis pathway which finishes with lactic acid. This is compensated by a very increased glucose uptake (10 to 17 fold higher) in cancer cell.
The fact that a tumor may be of the glutaminolitic phenotype does not mean that it does not get much of its energy from glucose.
I hope this will answer your question.
In the tumor cells, Glutamin is consumed within the reductive carboxylation to provide enrgy and anaploretic carbones in the TCA cycle. Eventually Glutamin is converted to Citrate and transfer to the cytoplasm of cancer cells to bring a precursor of fatty acids which is needed for cell membrane expansion. intrestingly It happpens reversely in the matrix of tumor mitochondrial. Glutaminolysis and Glutamin uptake are regulated by over expression of c-MYC, an oncoprotein which regulates glutamin and glucose metabolism in the tumor cells. because of cancer cells dependency to the c-MYC oncogene It seems that Glutamin is not the main source of cancer cells.
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