Move over!
How cancer cells make room for themselves
Kirill Stasevich, "Science and Life", based on materials Phys.org : Tumor cells conquer territory from their neighbors using a newly discovered mechanism.
We know that cancer cells divide uncontrollably, but they do not divide in the void – they are surrounded by other cells that form an organ. That is, it is not enough for tumor cells to simply be able to divide, they must somehow free up space for themselves. On the other hand, during individual development, when our organs and tissues grow, from time to time it happens that there are more cells than necessary. And in such cases, overpopulated tissue somehow gets rid of excess cells. It can be assumed that a malignant tumor somehow uses molecular cellular mechanisms that monitor the number of cells in order to win in the competition for free space.
Obviously, everything starts here with mechanical forces: cells feel that they are pressing on each other, and mechanical pressure includes certain molecular processes in them. At the same time, it is usually assumed that excess cells are simply squeezed out of the tissue. In fact, as researchers from the Portuguese Center for the Study of the Unknown Antonio Champalimaud (Champalimaud Centre for the Unknown) and the French Pasteur Institute (Moreno et al., Competition for Space Induces Cell Elimination through Compaction-Driven ERK Downregulation) write in Current Biology, cells die directly in the tissue using a special suicide program.
There are several such programs (the most famous among them is apoptosis), and no living organism can do without them, since programmed cell death not only helps to form organs, but also relieves the body of old, sick, dangerous cells. And if the suicidal program in the cells was turned off, then although those around them were strongly squeezed, they did not die and did not leave the tissue.
On the other hand, in experiments with drosophila epithelial cells, researchers found that mechanical stress suppresses the work of the EGFR/ERK molecular signaling pathway, which helps cells survive. EGFR and ERK are the names of key proteins that perceive certain signals from the outside and transmit them to intracellular performers, other proteins that affect the activity of certain genes and enzymes. While the EGFR/ERK signaling pathway is working, the suicidal program in the cell is not activated.
When normal epithelial cells grew surrounded by tumor cells, the EGFR/ERK signaling pathway protecting them from death was switched off in normal cells. Feeling mechanical deformations, they began to die, making room for tumor cells. However, tumor cells also feel pressure, so why don't they die themselves? The authors explain this by the fact that malignant cells usually have mutated genes responsible for programmed death.
At the same time, if this signaling pathway was specifically kept active, then normal cells remained alive, but tumor cells began to spread more slowly. Perhaps in the future it will be possible to restrain the growth of tumors, helping ordinary cells to hold their place and not give in to the mechanical competition of tumor cells.
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