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Mouse change human cancer

Once in the mice, human cancer cells develop differently than if they remained in man.


Cell lung cancer. (Photo: Science 3.0 / Flickr.com.)

In studies of cancer often use mice, which implanted with pieces of human tumors – these tumors are called xenografts. The method is somewhat unnatural, however, if we experiment on mice, which themselves are predisposed to malignant diseases have to take into account that cancer – murine, not human; and the mouse still is different from the person much. So transplantation of the tumor – a good way to create a model of the disease, more or less close to “human” conditions. In addition, in this way it is possible to study individual cases: taking from the patient a sample of the tumor and transplanted it into a mouse, it is possible to test it on a variety of treatment options to find something that will help this patient. (Although far not every patient has the time to wait until the swelling take hold of the mouse.)

Of course, such a method has its limitations. For example, the tumor transplanted mice with a faulty immune system your immune system with threshold did not reject foreign tissue. But the unemployed immunity is in fact quite peculiar conditions, and to assess the interaction of the immune system and tumor there. And generally here there is another question that probably some of the readers came up with: once cancer cells are in the “native” body, and in a strange, and even very different species – and whether they change in this new environment?

Researchers from the broad Institute decided to find out what is changing over time, human cancer cells that have to grow in mice. To do this, Todd Golub (Todd R. Golub)and his colleagues sampled 24 varieties of cancer and transplanted them into mice. After the tumor of the animal grew, it was transferred into a fresh mouse, and so several times. The results described in the article in Nature Genetics, which States that tumors in mice do behave differently than in person. For example, about glioblastoma cells – one of the types of brain cancer – known that they have over time, the extra copy of the seventh chromosome. But it’s the person, but when gets in the glioblastoma mice, the cells, on the contrary, lose the extra copy of the chromosome. Some of the “mouse” features in the cancer genome affect how cancer cells respond to drugs.

The authors believe that their results are not discrediting method xenografts, just need to understand more precisely what he do, and what not. For research purposes, such mice can be used, but for clinical – unlikely: after all, the patient can be treated in quite a different medication that he needs.

Probably something similar could be expected: cancer cells divide rapidly, and the advantage is given to those who are able to survive in a given environment; obviously, in the case of xenografts selection will favor those cells that are able to survive in mice. However, according to some experts, the mice with human tumors can be safely used in the clinic: in a recent article in Annals of Oncology , a large group of authors under the direction of David Sidransky (David Sidransky) from the Institute of Johns Hopkins claims that 87% of tumors, transplanted from patients into mice reacted to drugs the same in humans, in mice. Perhaps large differences have a place in the remaining 13% – maybe it was the fact that the authors of the article in Annals of Oncology analyzed the cases of all ninety two patients and positive result arose from the not very large statistics.

However, there were other researchers who questioned the fact that after transplantation of the tumor cells appear so large differences. Maybe it’s all in variations of the method. For example, cancer cells can be transplanted in different places – just under the skin, and can be in the same body in which they arise in humans. It seems obvious that cells of pancreatic cancer natural would be to put in a mouse pancreas, and not somewhere else. Anyway, the method of xenografted think professionals are too attractive to just abandon it, and, most likely, the radiation oncologist will do everything possible to transplanted tumors were most similar to human.

 

According to the materials Nature.

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