Cells with antisocial behavior
"Tumor cells live for themselves, they are selfish cells"
The material was prepared on the basis of the radio program "PostNauka" on the radio "Moscow Speaks". The presenter is the editor of the PostNauka project Anna Kozyrevskaya, the guest of the broadcast is Doctor of Biological Sciences, senior researcher at the Belozersky Research Institute of Physico–Chemical Biology of Moscow State University Yevgeny Sheval.
– What is the difference between "normal" cells in the body and their work from tumor cells?
– The paradox is that tumor and "normal" cells are no different at the cellular level. They differ in their relationship to the body. The cells of the body perform their functions, live and die as the body needs. Tumor cells live for themselves, they are selfish cells. There is a good saying that tumor cells are cells with antisocial behavior. This is the tumor.
Ultimately, the origin of a tumor is always a change in the genome of a cell, it may be mutations or other changes, but oncological diseases are genomic diseases. There are hereditary diseases that are passed down from generation to generation. Human cells are initially all the same, but individual cells can mutate. If this mutation does not affect any important process, then nothing terrible will happen. Eventually, probably, all cells will mutate, because the genome is not eternal, because cosmic rays are around us that can damage DNA molecules, mutagens, etc. But a mutation can somehow affect the reproduction of a cell or its death.
Cells in the body have their own life cycle – they live and die. The process of death is a clearly written program, there are special proteins responsible for ensuring that the cell dies in the right way at the right moment, so that it does not just disintegrate into pieces, but fragmented, then macrophages came and these pieces were "eaten". This is a complex programmable process. If the cell began to multiply a little better or die a little worse, then it changed its properties. It hasn't become a tumor yet, it's just one mutation. Then, among her descendants, someone can get another mutation, and selection begins among the cells, selection.
In fact, this selection is a Darwin selection. That is, random mutations occur, and then among the descendants with random mutations, those that are more out of control of the organism are selected. This process is in most cases lengthy. It is very rare that one mutation can lead to something similar to a tumor in medical terms. Nevertheless, the cells are gradually mutating, and clones are being selected, which are increasingly out of control of the body, becoming more and more antisocial, and we have a lot of such cells. There are quite a lot of tumors not only in humans, but also in any animal in the body. Any mole is a tumor. But it has not yet become dangerous to the body, that is, it has not become a tumor from the point of view of harm to the body, from a medical point of view. Yes, it has changed, yes, the body does not need this mole, but it already exists. It may not be dangerous, moreover, it may never become dangerous, as, for example, tumors from adipose tissue – lipomas are not dangerous. Human life is simply not enough to accumulate mutations and turn into a dangerous liposarcoma, so if the lipoma does not interfere with movement, does not spoil the appearance, it is not necessary to remove it.
But at some point, so many mutations can accumulate that the tumor becomes dangerous, and then a medical problem arises.: these are no longer just altered cells that are slightly different. When we talk about tumors, in most cases we think about this situation. But it is preceded by a long way of selecting clones with altered properties, with cells that can live for themselves, reproduce for themselves, getting out of control of the body, and, unfortunately, such cells are capable of killing the body by their behavior.
Tumors can be caused by a variety of reasons. For example, Burkitt's lymphoma. A very unpleasant tumor, the cells of which multiply very quickly. Its development is associated with the Epstein–Barr virus. This tumor is spread mainly in Africa. In Europe, in America, among the Caucasoid population, this is exotic. But in recent years it has become more relevant. This is due to the problem of HIV. This is a very serious disease, which they have now learned not to cure, but to restrain. There are drugs that must be taken for life, they will restrain the development of the disease, and the patient will live. But at this point, a tumor may appear. And, as it turned out, most often it is Burkitt's lymphoma.
– How does classical chemotherapy work on the body?
– Classical chemotherapy is based on two simple things. Any normal cell in the body is mortal, and often its lifespan is very short. I love the example of the intestinal epithelium: intestinal epithelial cells in a differentiated state live only 4-5 days, their limit is a week, and then they die. New cells are produced, old cells die, there is a continuous flow of cells. There are cells that are updated more slowly, for example, the cells of the pulmonary epithelium. There are cells that are practically not updated or not updated at all, like neurons. But nevertheless, cells are able to die. Tumors are cells in which the program of the correct change of life stages has been switched off: reproduction, differentiation and death. The tumor disabled this program. Any chemotherapy, exposure to radiation, heat (now there are a huge number of different approaches) in most cases pursue the goal – to cause a program of programmed cell death. Animals, as a rule, have several types of programmed cell death, most often it is apoptosis, in which the cell breaks into pieces and is then "intelligently" removed by macrophages. It can be said that the doctor's task is not to reduce the tumor, but to induce programmed cell death in tumor cells.
– That is, to make the cells start dying again?
– Yes, it is impossible to shoot the cage, but it is possible to call the program that is embedded in it. It's scarier when this program is broken. There is a very well-known protein, p53, one of the most studied proteins. If it does not work, then the cells go very badly into programmed cell death and such tumors, as a rule, are treated worse.
There are cases when it is necessary to launch not just death, but differentiation. The cell remained at the stage of reproduction: it reproduces, reproduces and does not want to differentiate, stop reproduction. It is impossible to work and reproduce at the same time, and such a cell must be pushed into differentiation. For example, for the treatment of acute promyelocytic leukemia, a very simple drug has been selected that causes cells to differentiate. This does not cure the tumor; as a rule, chemotherapy is additionally used, which in parallel will drive the cells into programmed cell death. It is much easier to kill a differentiating cell than a multiplying one.
– What are the methods of treatment of oncological diseases of the blood?
Now, when it comes to hematological oncological diseases, leukemias, lymphomas, they act by the method of maximum impact, since if you hit lightly, the tumor cells will survive and the tumor will relapse. But with this treatment, not only tumor cells die, but also normal stem cells that give blood. Since there is no selectivity yet and we cannot hit only tumor cells, we hit all stem cells, destroy them, and then it turns out that we have killed normal bone marrow. The only way out today is bone marrow transplantation.
– At what stages can cancer be diagnosed today and how, in your opinion, will this area develop?
– Of course, it's good to diagnose early. The tumor has its own history, tumor progression, you need to know it. If we know it, then we can understand at what stage to catch the tumor. In case of stomach cancer, it is necessary to catch at the stage of polyps. Yes, they are not dangerous, it's just an outgrowth in the stomach wall, which is perfectly visible during gastroenteroscopy. Tumors are an age–related phenomenon, it should take time for mutations to accumulate. If a person does a gastroenteroscopy after the age of 40, the doctor will see a polyp, cut it off, and then this person will not have stomach cancer. But if you miss this moment, the tumor may develop and surgery will be required. Moreover, metastases may occur, and the situation will become more complicated. Therefore, it is so important to diagnose the tumor on time. Of course, if it is polyps or skin cancer that is visible to the naked eye, it is easy to diagnose. But if the tumor is deep? A huge number of methods are being developed for such cases. For example, now in any polyclinic they put a reaction to cancer markers for several tumors, which are very common in Russia.
Cancer markers are, as a rule, proteins that are detected by antibodies. In large clinics there is a fairly wide panel of such cancer markers. If there is a danger that a person will have a certain type of cancer, it is better to be checked periodically. By the way, in the field of immunological methods of early diagnosis, the priority in science remains with Russia. The first cancer marker is alpha–fetoprotein, which was discovered by Harry Israelevich Abelev. And this, of course, should be a matter of our pride.
Portal "Eternal youth" http://vechnayamolodost.ru27.08.2014