Researchers from Lomonosov MSU Faculty of Biology have studied the stages of entosis, a process of cell death when one cell invades the other and gets digested inside of it. Entosis could become a new method of destroying cancer cells. The research was conducted as a part of the Noah’s Ark Project, with the results published in the Scientific Reports.
Entosis is one of the variants of programmed cell death, or one of the types of cellular cannibalism. The process consists of one cell absorbing another and getting destroyed in it. Any cell that can attach to another cell can engage in entosis. Tumor cells do it most often, and can consume both similar and healthy cells. Scientists think that with the help of entosis it could be possible, on the contrary, to destroy those cancer cells that are resistant to drugs that cause apoptosis, which is another variant of programmed death, in which the cell simply breaks up into separate apoptotic bodies.
The consuming (entotic) cell forms an outgrowth of the plasma membrane – a special fold that “covers” the invading cell. Then the plasma membrane “collapses” along the fold, so that the invading cell is placed inside the entotic vacuole, where it is held by specialized structures – desmosomes. Soon, the membrane from which the vacuole consists begins to change: desmosome proteins disappear, and their place gets taken by proteins that are needed to merge with lysosomes – the organelles which will then “digest” the invading cell. The lysosomes of the entotic cell merge with the vacuole membrane, and digestive enzymes enter the vacuole to destroy the invading cell. Inside the invading cell, too, lysosomes are activated and grow in number. As a result, the invading cell collapses and dies. The products that are formed during the splitting of proteins, DNA, lipids, polysaccharides and other molecules of the implanted cell can serve as an additional food for the entotic cell.