A new blood test could facilitate the detection of brain tumors.
Read out Malicious brain tumors could be detected and assessed in the future with a simple blood test. The basis for this has now been laid by US researchers: they have discovered that the tumors emit small, membrane-enclosed vesicles that are detectable in the blood and contain special recognition molecules. In a first test in 25 patients with glioblastoma, the most malignant variant of brain tumors, the method has already proven itself and in some cases even provided more precise information about the tumors than a tissue sample of the tumor, the scientists write. The process will now be further developed with the help of a biotechnology company. Glioblastomas are very aggressive malignant tumors that usually occur in the cerebrum. Once formed, the individual degenerate cells begin to actively reshape their immediate environment to give the tumor the best possible growth conditions. They use so-called exosomes, small membrane bags, which are pinched off from the tumor cell and partially absorbed by the neighboring cells. As the researchers have now shown, these bags contain various types of messenger and signaling molecules, including DNA-like pieces of RNA and various proteins. Among other things, these promote the growth of the tumor cells, allow the invasion of the surrounding tissue, suppress the body's defenses and stimulate the formation of new blood vessels for the supply of the tumor.

The composition of these signaling molecules is so characteristic of the glioblastoma that many characteristics of the maternal tumor can be determined solely from the contents of the sachets. Since the tumor cells also form and expel many exosomes, some of them enter the bloodstream through the blood-brain barrier. This is exactly what makes them so valuable: If the glioblastoma sacs are found in a blood sample, on the one hand without an imaging procedure or even a removal of tissue from the brain it is clear that the patient suffers from such a tumor. On the other hand, the molecules contained reflect the genetic makeup of the tumor and provide a rough indication of whether or not it will respond to a particular treatment.

In addition to the diagnosis, the exosomes are also a valuable tool to follow the course of therapy, explains study leader Johan Skog. If it does, then the properties of the tumor should also change, which in turn could lead to an adaptation of the treatment strategy. Since glioblastomas are not curable at the moment, such a monitoring and testing method would be very valuable for the development of new drugs. However, when the test will actually be available, the scientists do not give any information.

Johan Skog (Harvard University, Charlestown) et al .: Nature Cell Biology, Online Pre-Release, DOI: 10.1038 / ncb1800 ddp / science.de? Ilka Lehnen-Beyel advertisement

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