Cancer and immunity: a game of hide and seek

Oncogene helps tumors elude immune attacks

Anna Govorova, Infox.ru

Scientists from Stanford University (USA) and the University of Würzburg (Germany) have made an important step in the development of immuno-oncology, reports Infox. They found another target, the impact on which does not allow the cancer to escape from the immune response of the body. This target is the oncogene Myc.

The authors report on the results of their work in the latest issue of the journal Science: Casey et al., MYC regulates the antitumor immune response through CD47 and PD-L1)

Currently, immunotherapy of oncological diseases is actively developing. And great hopes are pinned on this direction.

If such methods of treatment as surgery, radiation and chemotherapy (including targeted) act directly on the tumor, then immunotherapy works on a different principle: with the help of certain drugs, they do not affect the tumor itself, but the patient's immune system so that it purposefully destroys cancer cells.

How a tumor eludes Immune attacks

Normally, the immune system should immediately recognize cancer cells and destroy them. But, unfortunately, this does not always happen. Why – for a long time remained a mystery.

As it became known quite recently, it is not a matter of weakening immunity (although this factor also plays a role), but that the tumor can elude the immune response. Currently, such escape routes are being actively studied in order to block them, enabling the immune system to work actively and destroy cancer cells.

A few years ago, for example, the CTLA4 and PD 1 antigens were discovered, which the tumor expresses in order to evade the immune response. This discovery led to the creation of drugs that block these antigens, and the inhibition of the immune response is removed. Such drugs (so–called inhibitors of regulatory molecules of key stages of the immune response) – antiSTLA4 monoclonal antibody and PD1 blockers - have already been registered in the USA and Europe for the treatment of metastatic and non-metastatic melanoma, small cell lung cancer and kidney cancer.

A few years ago, the authors of the current study discovered another antigen that allows the tumor to avoid an immune response –CD47. Currently, drugs that block its synthesis are undergoing the first stage of clinical trials for the treatment of various oncological diseases.

But, as it turned out, such drugs do not always work effectively.

Another player

One of the reasons for their inconstant effectiveness was found out quite recently. The fact is that, as the current experiment has shown, it is not enough to block the synthesis of proteins with which the tumor escapes from the immune response. There is another player in the process – the oncogene Myc.

During the study, scientists were able to find out that there is a relationship between the level of expression of the Myc oncogene and how many CD47 and PD 1 proteins are formed on the surface of cancer cells. This association has been shown for acute lymphoblastic leukemia, liver cancer, melanoma, and non-small cell lung cancer. A study of the database of cancer patients showed that the level of Myc expression also reliably correlates with CD47 and PD 1 levels in kidney and colon cancer cells. It turned out that the more active Myc expression is, the more CD47 and PD 1 antigen proteins are formed on the surface of a cancerous tumor. It turns out that the synthesis of these antigen proteins regulates Myc.

"The most important thing that we managed to show in our work is that it is necessary to block the action of not only CD47 and PD 1 proteins, but also the expression of the Myc oncogene. Then you can slow down or stop the growth of the tumor. This opens the way for the active work of the body's immune system to destroy cancer cells," says (in a press release from Stanford University School of Medicine, lead author of the study, Professor Dean Felsher (Dean Felsher).

"Now there is a growing understanding that immunotherapy has huge opportunities in the treatment of cancer. In many cases, this method really works. But it is also clear that some types of tumors are more sensitive to immunotherapy, while others are less. Our work shows that there is a link between the level of oncogene expression and the immune response of the body. And it is very important to continue studying this phenomenon in order to help our patients," adds Professor Felscher.

Portal "Eternal youth" http://vechnayamolodost.ru  16.03.2016