Researchers at the FDA and the National Institutes of Health may begin Phase I trials of a new treatment for AIDS-related Kaposi's Sarcoma (KS) based on results reported in the July 1, 1999 issue of Nature Medicine. KS is the most common tumor of people infected with the Human Immunodeficency Virus (AIDS virus). The tumor can be fatal despite treatment with highly active anti-AIDS virus drugs. KS begins as purple nodules on the skin that can spread to other parts of the body. Almost all types of KS tumors including AIDS-related KS contain human herpes virus 8 (HHV-8) DNA. HHV-8 and the AIDS virus may work together to cause a KS lesion to develop into cancer.
KS tumor cells have on their surfaces proteins (receptors) with a high binding ability for interleukin-4 (IL-4). IL-4 is produced by certain white blood cells in our bodies and is able to slow the growth of KS tumor cells. The reason KS cell cultures express large amounts of the interleukin-4 (IL-4) receptor is not yet know. However, Raj Puri and colleagues exploited the ability of IL-4 to target KS cells and attached a bacterial toxin, from Pseudomonas aeruginosa, to IL-4. The KS tumor cells take in the IL-4 bacterial toxin chimera by binding to the IL-4 portion (chimera= A protein created by joining fragments from two or more different organisms. In this case mouse IL-4 and a bacterial toxin.). Once inside the KS tumor cell the bacterial portion of the chimera kills the cancer cell.
When they injected this IL-4 bacterial toxin in mice that had KS tumors they were able to completely eliminate the KS tumors. This is not proof that it will work in humans. However, it may eliminate KS tumors in AIDS patients and provide a new approach to eliminating other cancers.
Take Care and Think Microbiologically!
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