Geneticists have found, as skin cancer makes himself invulnerable to chemotherapy

© Fotolia / Spectral-Design3D image of a cancer cell<img src="/wp-content/uploads/sites/5/2017/09/5586c8300ba007137d3012e49b8c69cc.jpg" alt="Geneticists have found, as skin cancer makes himself invulnerable to chemotherapy” />© Fotolia / Spectral-Design

Aggressive form of melanoma, skin cancer, are almost impossible to treat for the reason that their cells are learned actively to develop a kind of «immunity» to the effects of chemotherapy, say scientists in an article published in the journal Nature.

«Cancer cells have proven to be very smart. When drugs block one of the main channels of growth, they activate other chains genes, allowing them to use alternative strategies of growth and reproduction. This leads to the development of more aggressive forms of the disease,» said GU Wei (Wei Guo) from the University of Pennsylvania in Philadelphia (USA).

According to official statistics of the who, prolonged sun exposure is the main cause of developing melanoma and other forms of skin cancer. This is due to the fact that ultraviolet radiation of light, or directly destroys the DNA or interacts with molecules in our skin cells and turns some of them into carcinogens. Each year new victims becomes about 132 thousand of the inhabitants of the Earth.

Annually in Russia is diagnosed up to 9 000 new cases of melanoma, which is the most common malignant tumor that metastasizes quickly. Over 40% of patients with melanoma of the skin cannot save due to late detection of the tumor, whereas with early diagnosis of melanoma is treatable in 90% of cases.

In recent years, as GU says, scientists have created several new types of chemotherapy, where the doctors injected in patients is not one but several different types of medications that suppress the multiplication of cancer cells. Originally this cocktail works very well, in fact, completely stopping the growth of metastases, but after about six months the cancer becomes immune for their actions and the patient dies, and the reason for this remained a mystery to scientists.

Trying to figure out why this is happening, GU and his colleagues have traced the changing work of the cancer cells in those cases, if they live in an environment where there are a large number of molecules of such substances.

As a rule, almost all of these drugs block the gene BRAF, one of the conductors of the activity of genes of growth, the damage which both enables them and blocks the protein p15, which is responsible for growth suppression of tumors. Blocking BRAF and related genes, the researchers hoped to stop the growth of tumor and make it vulnerable to attack by immune cells.

As it turned out, this stop of growth is actually carries with it an even greater threat to the health of the patient is part of the cancer cells do die, but their more successful «neighbors» stop using BRAF for their growth and move to the other chain genes associated with the enzyme PAK. Like his «colleague» BRAF, the protein not only stimulates the growth of cells, but also blocks the mechanisms of cell self-destruction.

When the scientists blocked and PAK and BRAF, they managed to significantly slow the growth of cancer cells in test tubes and in tissue samples of patients. Now GU and his colleagues are studying the whole chain of genes, which is controlled by the enzyme PAK, and try to find among them «the weakest link», the attack on which will really extend the life of people with melanoma.