Why do tumors blow bubbles?
Scientists at McGill University, working under the guidance of Dr. Janusz Rak, have discovered a new fundamental mechanism by which tumors interact with the body. The results of their work were published on 20.04.2008 in the electronic version of the journal Nature Cell Biology.
The researchers found that tumor cells release vesicles (membrane vesicles) containing oncogenic proteins capable of penetrating into healthy or less malignant cells and triggering metabolic pathways characteristic of highly malignant cells in them. This discovery can completely change existing ideas about the functioning of tumor tissue and, accordingly, approaches to antitumor therapy.
It has long been known that the cells of some brain tumor cells express a mutant version of the III variant of the epidermal growth factor receptor (variant III epidermal growth factor receptor, EGFRvIII). Despite the fact that this factor is expressed only on a part of tumor cells, it is an important indicator of the malignancy of the entire tumor. For a long time, scientists could not answer the question: why does a small number of cells play such an important role?
The authors demonstrated that the mutant version of EGFRvIII ensures the formation of small vesicles bearing copies of EGFRvIII on their surface. These vesicles, called oncosomes, migrate until they merge with a healthy or less malignant tumor cell. At the same time, the oncogenic protein EGFRvIII integrates into the membrane of the recipient cell and changes their functioning in an undesirable way: it accelerates the division of healthy or not too aggressive cells and stimulates the growth of blood vessels.
This information suggests that many mutant proteins do not necessarily remain in the composition of the cell that synthesized them. They can migrate through the body as part of oncosomes, forming the "oncogenic field effect". The data obtained indicate that, contrary to traditional ideas, according to which a tumor is formed as a result of uncontrolled division of one mutated cell, malignant growth is a process in which many cells actively interact with each other participate.
The presence of oncosomes containing EGFRvIII or other proteins in the blood of oncological patients may eventually become a clinical marker capable of replacing biopsy in some cases. Such a non-invasive method is especially important for the diagnosis of brain tumors: currently, obtaining their molecular characteristics is possible only after their removal. Preliminary diagnostics based on the analysis of a small sample of cerebrospinal fluid will allow you to choose the optimal treatment tactics in advance.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
23.04.2008