Hello.
I have a question about these two behaviors, the Warburg and Crabtree effects. I am a master's student and my teacher said to me that Warburg occurs in cancer cells and Crabtree in yeast, basically that the Warburg effect on cancer is analogous to the Crabtree effect on yeast. However, I see some scientific articles that say that cancer cells have both. In yeast, I understand that high concentrations of glucose inhibit oxidative respiration. I am confused. Can someone explain this to me? Cancer cells only exhibit the Warburg effect or also exhibit the crabtree effect?
Thanks
Dear João Silva,
Many/most cancer cells are in a state of constant cell division. When cells divide (normal and cancerous) the cells slightly increase their intracellular pH and switch to aerobic glycolysis for their energy. This is done to protect the DNA from mutation while it is being copied (the increase in pH decreases purine spontaneous deamination and depurination reactions etc., and the shutting down of the mitochondrion decrease the production of ROS that can lead to DNA damage. Since cancer cells are often in a near constant state of cell division they appear to use almost exclusively aerobic glycolysis for their energy at all times. This is the Warburg effect.
In yeast when the glucose concentration is very high, it is advantageous for the yeast to also use glycolysis (in this case generating ethanol) at all times, as it is energetically more efficient (less costly to the yeast..... less energy required to synthesis the glycolytic enzymes only) to use glycolysis. This is the Crabtree effect, and a similar strategy is often used by parasites see the below publication.
Article The activity of crude bromoacetyl-L-carnitine preparations a...
Phil
Hello João Silva
The “Warburg effect” is defined as an increase in the rate of glucose uptake and preferential production of lactate, even in the presence of oxygen. The normal differentiated cells will rely primarily on mitochondrial oxidative phosphorylation to generate the energy needed for cellular processes. But cancer cells instead will rely on aerobic glycolysis, a phenomenon which is termed as “Warburg effect”.
Aerobic glycolysis is an inefficient way to generate ATP, however, the advantage it confers on cancer cells has been unclear. But there is a thought stating that cancer cells acquire and metabolize nutrients in a manner conducive to proliferation rather than efficient ATP production, and the associated mutations acquired by cancer cells enable them to function in this manner.
In some cancer cells, sometimes, depending on the absence or the presence of glucose and the environmental conditions, the cancer cells can reversibly switch between fermentation and oxidative metabolism. This short-term and reversible event is referred to as the “Crabtree effect”. This reversible shift might be an advantage to cancer cells, as it would allow them to adapt their metabolism to the rather heterogeneous microenvironments in malignant solid overgrowths.
So, cancer cells show both the effects, depending on the environmental conditions, they can switch reversibly.
Your teacher is right when he/she said that the "Crabtree" occurs in yeast. Some yeast species such as S. cerevisiae use fermentation even in the presence of oxygen when glucose concentrations are sufficiently high. The use of fermentation in the presence of oxygen and at high glucose concentrations is referred to as the “Crabtree effect”. Yeasts that display a “Crabtree effect” are Crabtree-positive while yeasts that do not display a “Crabtree effect” are Crabtree-negative.
You may want to refer to the article attached below for more information on “Crabtree effect” in yeast.
Article Analysis on yeast short-term Crabtree effect and its origin
So, when high concentrations of glucose or fructose are added to the culture medium, respiration is frequently inhibited. This phenomenon of “Crabtree effect” is observed in numerous cell types, particularly you will find this effect in proliferating cells, which would include not only tumor cells but also yeast.
Hope this clears your doubt!
Best.
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