2018-01-14 14:29:41
The biggest problem with antitumor drugs is that they not only affect cancer cells but also damage many normal cells, particularly cells of the immune system, causing immunosuppression and serious side effects.
Research to develop strategies based on immunotherapy tries to alleviate this serious problem. These strategies try to modify and stimulate certain cells of the immune system so that they identify as foreign, attack and eliminate tumor cells, without affecting normal ones.
These strategies are not without problems either. Genetic modification of lymphocytes can lead to excessive activation of lymphocytes, which can cause serious deleterious effects. In addition, the effectiveness of this type of strategy depends on numerous encounters between lymphocytes and tumor cells, which is not always the case, since various types of tumors are difficult for these cells to access.
Now researchers at the University of Basel, in Switzerland, use a type of embryonic cell known to be attracted to tumors, so it will go in search of it naturally. On these cells they carry out a sophisticated biomolecular engineering that turns them into killer cells, although they only kill tumor cells.
First, scientists modify cells so that they make an enzyme, which will activate a chemical reaction that turns a harmless substance into a deadly poison for cells. They introduce a second modification into the cells: genes that manufacture specific proteins on their surface that act as a safety, which performs a function similar to the safety that firearms have. Finally, they also introduce genes into cells that make a device capable of detecting tumor cells, and only them. This device is made up of a molecule, which is also located on the surface of cells, which serves as a detector of a protein typical of tumors. As long as the detector protein does not detect the tumor molecule, the insurance molecules prevent the enzyme from acting. Thus, the killer cell is completely harmless. However, when it detects the tumor molecule as it passes by a cancer cell, then, and only then, will the lock be inactivated and the enzyme released into the vicinity of the cell, turning the harmless substance into a toxic one.
The researchers test the efficacy of these designer killer cells against tumor cells in culture flasks in the laboratory. The nutritive medium in these flasks, which allows the cells to live and grow, also contains the innocuous substance that will only become toxic if the enzyme is released into the external environment by the modified cells, which will only happen when they detect a cell. tumor. At that point, the released enzyme will transform the harmless substance into a poison that will kill nearby cells, including the killer cell itself. This cell thus commits involuntary suicide, but in doing so, it also kills several of the nearby tumor cells.
At the moment, these designer cells have not yet been tested in laboratory animals. This will be the next step of this investigation. If these cells prove to be effective against one or, perhaps, against several types of tumors in these animals, clinical trials with patients would be carried out to test the effectiveness of this methodology in real cases.
Reference:
Ryosuke Kojima et al (2017). Nonimmune cells equipped with T-cell-receptor-like signaling for cancer cell ablation
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