A new study by the Massachusetts Institute of Technology (MIT) scientists has discovered how cancer cells use an unusual multiplication process. The study, which answers a long-standing mystery about the proliferating unhealthy cells in the human body, will be published in Molecular cell log.
The study was conducted by MIT biologists Matthew Vander Heiden, senior author on the new study, and the lead authors, former MIT graduate student and postdoctoral fellow Alba Luengo (PhD ’18) and graduate student, Zhaoqi Li. Their research showed that a metabolic procedure known as fermentation helps cancer cells regenerate large amounts of a molecule called NAD +, which they need to synthesize DNA and other important molecules. Heiden told MIT News that according to their research, cells must under certain conditions perform more of the electron transfer reactions, which require NAD + to make molecules such as DNA.
Fermentation is a way for cells to convert the energy in sugar into adenosine triphosphate (ATP). ATP is a chemical used by cells to store energy for their needs. People use a process called aerobic respiration, in which cells break down the sugar to access more ATP. However, cells switch to a less efficient method called fermentation when there is a lack of oxygen in the cells.
German chemist Otto Warburg discovered that it is mostly the cancer cells that metabolize sugar through fermentation. Scientists have since proposed several theories to justify why cancer cells switch to a more lethargic way of breaking down cells, but with little success.
To understand this reason, MIT scientists have prevented the cancer cells’ ability to carry out the fermentation process. With this they saw that the growth of cancer cells was stunted. The researchers then introduced a different method of cell growth by stimulating the cells to produce NAD +, a molecule that helps cells get rid of the extra electrons left over when cells make molecules such as DNA and proteins.
With this experiment, researchers found that the cells started to proliferate again, despite their inability to carry out fermentation. The results of this study led researchers to conclude that when cells grow rapidly, they require NAD + more than ATP. And since cells produce a lot of ATP and some NAD + during aerobic respiration, they switch to fermentation. Scientists found that when cells accumulate more ATP than they can consume, their breathing calms down and NAD + production also decreases.