Tuesday, January 15, 2013

Cancer drug may treat severe muscle disease

After a drug is brought on the market for a specific use, follow-up studies sometimes reveal surprising new ways to use it. Perhaps the most famous example is aspirin, which was approved decades ago, but has since then seen a large increase in ways it can be used. In addition to its use as a painkiller, it has been shown to cut down the risk of cardiovascular diseases, as well as cancer. Now, a collaboration between the University of Geneva and the University of Lausanne revealed that a well-known breast cancer drug can also be used for something totally different: they showed that it may be used to treat a severely debilitating muscle disease, to which currently no cure is available.

The investigated drug is called tamoxifen and is commonly used to treat breast cancer. It functions by blocking the estrogen receptor, which in some tumours is required for growth of the breast tissue. However, it appears to have more effects than simply blocking access to a receptor, as scientists previously discovered that it also affects the levels of proteins that are associated with muscle function.
Molecular structure of tamoxifen.
One of the most severe diseases of the muscular system is Duchenne. It results in progressive loss of muscle function, which eventually leads to death due to cardiac or respiratory arrest. It is caused by a faulty dystrophin gene, resulting in faulty production of its associated protein. Currently, there is no way to stop the disease from destroying a person's life, and patients with Duchenne often die young. A treatment is therefore highly desirable, which is why the scientists investigated whether tamoxifen's effect on the muscles could be of any use.

At the University of Geneva and University of Lausanne, mice experiments showed that the degree of damaged heart tissue dropped by around 50 percent after treatment with tamoxifen. In the diaphragm, needed for movements related to breathing, the damage dropped about 72 percent. Tamoxifen treatment also markedly improved structure of the legs, and resulted in more resistance against fatigue. After a year of treatment, muscle performance in the experimental group was almost on the level of ordinary mice, indicating that tamoxifen significantly ameliorates the symptoms. One can only hope it works in similar fashion in humans.

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