We very often see scientific news about malignant tumors, cancer cells, about new anti-cancer drugs, but we do not always pay attention to how the researchers worked with cancer in each specific case. For example, drugs: a new drug, after all, does not begin to be immediately studied in humans. And on what is it then studied? There are different options here. For example, a laboratory cell culture: cancer cells endlessly grow in a layer in a nutrient medium, and we subject them to various tests. Or, for example, you can take a laboratory mouse: either it will have a mutation that causes cancer, similar to a human, or the mice simply transplant a sample of a human tumor and it lives with it. Or there is another, third option: to grow a tiny three-dimensional tumor, similar to how organelles are grown – microscopic similarities of the intestines, stomach, cerebral cortex, etc.
Obviously, cells that grow as a layer in laboratory glassware and all other forms of cancer in the laboratory are not exactly the same as a real tumor. It’s not even about mutations: with the same mutations, cells can react differently to what is happening around them, depending on the conditions in which they live. Staff Johns Hopkins University compared real tumors with laboratory cell cultures, transplanted tumors and tumor organelles. They were compared with each other by RNA. In order for the genetic information in DNA to work, it must be copied into RNA, and then proteins will be synthesized on RNA, or the RNA molecules themselves will somehow function in the cell. By the level of a particular RNA, one can understand how active a particular gene is: the more active the gene, the more RNA corresponding to it in the cell.
The researchers took 22 types of tumors for comparison. These were tumors, about which it was long known how they behave in the “natural environment”: tumor samples taken from patients were analyzed many times for gene activity. On the other hand, for the same tumors there are several hundred cell lines that have been grown for more than a decade in laboratories around the world, there are several hundred types of xenografts (this is the name of human tumors that are transplanted from animal to animal), there are more than one hundred tumor three-dimensional organelles, there are more than twenty strains of mice that have the desired tumor mutations in their genes.
In an article in Genome Medicine it is said that cell cultures were the least similar to real tumors. In one case, prostate cancer cells, when they were grown in a layer in a nutrient medium, turned out to be more like bladder cancer rather than real prostate cancer. In general, such results could be expected: when cells grow in a flat layer on the bottom of some dish, they even interact with each other differently than in a real tumor. Therefore, an organoid in which cells are surrounded on all sides by other cells will already look more like a real tumor. And if cancer cells grow in a real organism (even if it is a laboratory mouse), then they will all the more behave as in a real tumor.
Cell cultures are, of course, much easier to handle and cheaper than other ways to grow cancer cells. And, of course, it is hardly worth neglecting the results obtained in experiments with cell cultures. However, if we want to better understand malignant processes, if we want to accelerate progress in the treatment of oncological diseases, then it is still advisable to double-check the obtained results – at least the most important ones – on experimental models that are most similar to real cancer.
Source: Автономная некоммерческая организация "Редакция журнала «Наука и жизнь»" by www.nkj.ru.
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