Bacillus anthracis bacteria (image) have very efficient machinery for injecting toxic proteins into cells, leading to the potentially deadly infection known as anthrax. A team of MIT researchers has now hijacked that delivery system for a different purpose: administering cancer drugs. “Anthrax toxin is a professional at delivering large enzymes into cells,” says Dr. Bradley Pentelute, the Pfizer-Laubauch Career Development Assistant Professor of Chemistry at MIT. “We wondered if we could render anthrax toxin nontoxic, and use it as a platform to deliver antibody drugs into cells.” In an article published online on September 22, 2014 in the journal ChemBioChem, Dr. Pentelute and colleagues showed that they could use this disarmed version of the anthrax toxin to deliver two proteins known as antibody mimics, which can kill cancer cells by disrupting specific proteins inside the cells. This is the first demonstration of effective delivery of antibody mimics into cells, which could allow researchers to develop new drugs for cancer and many other diseases, says Dr. Pentelute, the senior author of the paper. Antibodies — natural proteins the body produces to bind to foreign invaders — are a rapidly growing area of pharmaceutical development. Inspired by natural protein interactions, scientists have designed new antibodies that can disrupt proteins such as the HER2 receptor, found on the surfaces of some cancer cells. The resulting drug, Herceptin, has been successfully used to treat breast tumors that overexpress the HER2 receptor. Several antibody drugs have been developed to target other receptors found on cancer-cell surfaces.
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