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Archive - Apr 28, 2013


Mapping of Cancer Cell Fuel Pumps Paves Way for New Drugs

For the first time, researchers at Karolinska Institutet in Sweden have managed to obtain detailed images of the way in which the transport protein GLUT transports sugars into cells. Because tumors are highly dependent on the transportation of nutrients in order to be able to grow rapidly, the researchers are hoping that the study, published in Nature Structural & Molecular Biology, will form the basis for new strategies to fight cancer cells. In order to be able to fuel their rapid growth, cancer tumors depend on transporter proteins to work at high speed to introduce sugars and other nutrients that are required for the cell's metabolism. One possible treatment strategy would therefore be to block some of the transporters in the cell membrane which operate as fuel pumps, thus starving out and killing the cancer cells. One important group of membrane transporters is the GLUT family, which introduces glucose and other sugars into the cell. Glucose is one of the most important energy sources for cancer cells and GLUT transporters have been shown to play a key role in tumor growth in many different types of cancer. In the current study, researchers from Karolinska Institutet have performed a detailed study of the way in which suger transport is executed by the protein XylE, from the Escherichia coli bacterium, whose function and structure is very similar to GLUT transporters in humans. For the first time, the researchers have described the way in which the protein's structure changes between two different conformations when it binds and transports a sugar molecule. "In showing details of the molecular structure of the region that binds the sugar, our study opens up the opportunities to more efficiently develop new substances that may inhibit GLUT transporters", says Dr.

Gilead Drug Induces Loss of Infected Cells in Chimp Model of Hepatitis B

A novel drug developed by Gilead Sciences and tested in an animal model at the Texas Biomedical Research Institute in San Antonio suppresses hepatitis B virus infection by stimulating the immune system and inducing loss of infected cells. In a study conducted at Texas Biomed's Southwest National Primate Research Center, researchers found that the immune modulator GS-9620, which targets a receptor on immune cells, reduced both the virus levels and the number of infected liver cells in chimpanzees chronically infected with hepatitis B virus (HBV). Chimpanzees are the only species other than humans that can be infected by HBV. Therefore, the results from this study were critical in moving the drug forward to human clinical trials which are now in progress. The new report, co-authored by scientists from Texas Biomed and Gilead Sciences, was published online on February 14, 2013 in Gastroenterology. Gilead researchers had previously demonstrated that the same therapy could induce a cure of hepatitis infection in woodchucks that were chronically infected with a virus similar to human HBV. "This is an important proof-of-concept study demonstrating that the therapy stimulates the immune system to suppress the virus and eliminate infected liver cells," said co-author Robert E. Lanford, Ph.D., of Texas Biomed. "One of the key observations was that the therapy continued to suppress virus levels for months after therapy was stopped.” The current therapy for HBV infection targets the virus and works very well at suppressing viral replication and delaying progression of liver disease, but it is a lifelong therapy that does not provide a cure. "This GS-9620 therapy represents the first conceptually new treatment for HBV in more than a decade, and combining it with the existing antiviral therapy could be transformative in dealing with this disease," stated Dr.