Stop the development of cancer?
The myth of the immortality of cancer cells has been debunked
Roman Ivanov, Computer
In cancer cells, the normal mechanisms that control the life cycle lose their effectiveness. Malignant cells acquire the ability of unlimited division, while refusing to die in the allotted time for normal cells, which leads to the formation of a tumor.
Scientists from the Federal Polytechnic Institute of Lausanne (Switzerland) have discovered a protein complex capable of regulating even this unregulated process, and now they hope that they will be able to learn how to stop the formation of malignant neoplasms.
All cells of our body are equipped with an automatic self-destruction mechanism: among other things, they are programmed to die after a certain number of divisions. These internal clocks are of the greatest interest to oncologists, since most forms of cancer demonstrate a defect in this "innate" quality. A cancer cell continues to divide an infinite number of times, much surviving the moment after which any healthy cell would voluntarily end its existence. Researchers led by Joachim Lingner have found out how malignant cells manage to bypass the self-destruction mechanism. Scientists also hope that their discovery will provide new targets for chemotherapy.
A report on the work done (Chen et al., The human CST complex is a terminator of telomerase activity) is published in the journal Nature.
a: Reduction of telomere length during replication.
b: The action of telomerase to restore the length of the telomere.
c: Bright white spots are the telomeric part of chromosomes.
(Fig. D. Sadava "Life: The Science of Biology".)
At the ends of each chromosome there is a special repeating DNA sequence known as a telomere; its length is increased or maintained at a constant level by the enzyme telomerase. Telomeric sections of chromosomes are characterized by the lack of the ability to connect with other chromosomes or their fragments and perform a protective, stabilizing chromosome function. If telomerase is inactive, the telomere is a measure of the cell's lifespan: after each division, the telomere is shortened until it disappears altogether, then the self-destruction mechanism is triggered. Thus, healthy cells are able to divide only a limited number of times, namely 50-60 (the Hayflick limit).
Usually, after the end of the embryonic stage, our cells stop producing telomerase (with the exception of somatic stem cells, as well as some other types of cells that need to be constantly divided for certain tissues to work, for example, intestinal epithelial cells). But sometimes cells mutate in such a way that they manage to reactivate the production of the enzyme, and then telomeres are not shortened. This is exactly what provides cancer cells with immortality.
By itself, such a mutation is insufficient for the occurrence of the disease, but cellular immortality is the most important factor in the formation of 90% of all known malignant tumors. It is also interesting that even in cancer cells, telomeres do not lengthen indefinitely. After each division, like healthy cells, they also lose about 60 nucleotides, which are then restored by active telomerase. Thus, the internal clockwork is reset to zero again, and the cell becomes immortal. And here the question arises: what prevents telomeres from lengthening indefinitely?
The Swiss seem to have found the answer: they identified three proteins that join together and then attach to telomeres. Being something like a lid on a saucepan, this protein complex prevents the interaction of telomeres with telomerase. Unfortunately, in cancer cells, the protein complex is triggered too late, allowing the telomere length to be restored to its original state.
Thus, if it were possible to make this protein complex react faster or it would be possible to artificially reproduce this mechanism (which, by the way, should be the easiest, since the experience in developing means of blocking the interaction of proteins, in this case telomeres and telomerase, is enormous), then cancer cells would cease to be so immortal and die it would be like all healthy cells.
Prepared based on the materials of the Federal Polytechnic Institute of Lausanne:
Demystifying the immortality of cancer cells.
Portal "Eternal youth" http://vechnayamolodost.ru06.07.2012