Scientists from Russia and the United States have discovered another defense mechanism for cancer cells. It turned out that in malignant neoplasms, the mechanism of DNA repair is preserved after exposure to radiation or chemotherapy. At the same time, such a system does not notice the accumulation of mutations due to frequent cell division. The article was published in the Heliyon magazine.
Healthy cells have a special mechanism for checking the quality of DNA. A special protein looks for errors in genes and corrects them. If the inconsistency cannot be corrected, such a cell dies. In constantly dividing cancer cells, genes inevitably accumulate mutations; nevertheless, the cells do not die off and the tumor continues to divide.
Previously, scientists assumed that DNA repair mechanisms do not work in cancer, since mutations do not prevent cells from dividing normally. It turned out that this system works even better in a tumor than in healthy tissues. This is what allows malignant neoplasms to protect themselves from chemotherapy and radiation, which cause many mutations. Researchers from the Moscow Institute of Physics and Technology, the National Medical Research Center of Endocrinology and Sechenov University, together with colleagues from the United States, found out that cancer cells can turn off the DNA quality check before dividing, and the rest of the time the protection system continues to work.
The scientists compared the activity of defense systems in samples of cancer, benign tumors, and healthy thyroid tissue. It turned out that this mechanism works most actively in cancer, and weakly in healthy tissues. After analyzing all the publicly available data for several tens of thousands of samples of different types of cancer, scientists found the same picture as for thyroid cancer. All defense mechanisms were activated in cancer samples, with one important exception. The pathways that carry out a kind of “quality control” of the synthesized DNA immediately before the start of cell division behaved in the opposite way.
“It turned out that in tumor cells everything works in a completely different way: in order to somehow preserve DNA at high rates of division, recovery also proceeds at a frantic pace. But before division, control mechanisms are no longer needed – otherwise all new cancer cells would simply have to die, ”said Anton Buzdin, head of the study, head of the laboratory for translational genomic bioinformatics at the Moscow Institute of Physics and Technology.
Author: Daryana Chesnokova
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