A new study by the scientists of the Massachusetts Institute of Technology (MIT) has found how cancer cells use an unusual process of multiplying. The study, that answers a longstanding mystery on the proliferating unhealthy cells in the human body, will be published in Molecular Cell journal.
The study was conducted by MIT biologists Matthew Vander Heiden, senior author of the new study, and the lead authors, former MIT graduate student and postdoc Alba Luengo (PhD ’18) and graduate student, Zhaoqi Li. Their research showed that metabolic procedure, known as fermentation, helps cancer cells to regenerate large quantities of a molecule called NAD+, which they need to synthesize DNA and other important molecules. Speaking to MIT News, Heiden said that according to their study under certain circumstances, cells need to do more of the electron transfer reactions, which require NAD+ in order to make molecules such as DNA.
Fermentation is one way that cells can convert the energy found in sugar to Adenosine triphosphate (ATP). ATP is a chemical used by cells to store energy for their needs. Humans use a process called aerobic respiration where 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 cells.
German chemist Otto Warburg discovered that it is usually the cancer cells that metabolize sugar using the process of fermentation. Scientists have since then proposed various 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 prevented the cancer cells’ ability to perform the process of fermentation. With this, they observed that cancer cells growth was hampered. The researchers then introduced another method of cell growth by stimulating the cells to produce NAD+, a molecule that helps cells to dispose of the extra electrons that are left out when cells make molecules such as DNA and proteins.
With this experiment, researchers found that the cells started proliferating again, despite their inability to perform fermentation. The results produced by this study led researchers to conclude that when cells are growing rapidly, they need NAD+ more than they need ATP. And since in aerobic respiration, cells produce a great deal of ATP and some NAD+, they switch to fermentation. Scientists found that if cells accumulate more ATP than they can consume, their respiration sedates and production of NAD+ also reduces.