Cancer cells have a combination of aerobic glycolysis and oxidative phosphorylation in producing ATP. Knowing which is the major producer of ATP can give the clinician and idea which pathway can be blocked to get a best response to cancer treatment. My understanding is that aerobic glycolysis can be increase by 10 fold while oxidative phosphorylation can not increase rate of ATP production from its steady rate.
As a matter of fact cancer cells produce more lactate than non cancer cells, that means that they rely more on anaerobic glycolysis than on oxidative phosphorylation. Since fermentation of glucose to lactate produce only 2 ATP per glucose while oxidative phosphorylation produces more than 30 ATP per glucose, cancer cells consume a lot more glucose to maintain their ATP. pool (Warburg effect).. On the other hand, fermentation is a very fast way to phosphorylate ADP and, in the presence of high amount of glucose available, is the best way to sustain a fast cell growth or a fastt ATP consumption (see in yeast as well as in fast contracting muscle). There are a lot of good review on Warburg effect in cancer cells
Due to the reason that both glycolysis and oxidative phosphorylation can compete with each other for NADH in cellular metabolism. Normally, the rate of mitochondrial oxidative phosphorylation is much greater and fastes over than glycolysis rate in cells without tumorgenesis. In contrast, cancer cells must overcome the inhibitory effect of glycolysis by mitochondrial respiartion and raises enouphly their glycolysis rate mainly for the perpose of provision of nucliotides sources from glycolysis - pentase-phosphate metabolism passway, which is nedeeded for DNA synthesis in cellular tumorgenesis. At same time, cancer cell also needs ATP support from mitochondrial oxidative phosphorllation , although some sort of ATP from cytosolic glycolysis could be also as other source of ATP for tumor cell growth. In one word, normal cells have greater rate of oxidative phosphorylation than glycolysis, and cancer cells must have larger glycolysis over than mitochondrial respirative phosphorylation.
While cancer cells do have increased rates of glucose consumption compared to normal cells, they still generate most of their energy via oxidative phosphorylation.
http://www.ncbi.nlm.nih.gov/pubmed/11988105
Firstly, we need to remember ourselves that tumour cells have limited mitochondria, which means they would not be able to produce ATP through Oxidative phosphorylation because Complexes 1-4 and F0F!ATPase are all mitochondrial enzymes.
Now, the only way for these stubborn cells to survive this situation is to make the most of their normal glycolytic process by increasing its rate. That is why cancerous cells undergo glycolysis more than 5-6 times of normal cells. The production of pyruvate would only give them 2ATP while the NADH produced by GAPDH and LDH would not be efficiently converted because of the absence of mitochondria. So, most of the ATP produced in cancerous cells are from increased rate of glycolysis (Substrate Level Phosphorylation) where most ATP produced by normal cells are from Oxidative phosphorylation. This is because normal cells have their Mitochondria smiling and all the Complexes are panting for the transfer of electrons that would hike up the Gibbs free energy that woud then be used by Complex V to convert ADP +Pi to ATP.
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