Prevent Disease.com - Protein Controls Tumor's Blood Supply



		Protein Controls Tumor's Blood Supply Excerpt By Merritt McKinney, Reuters Health NEW YORK (Reuters Health) - Scientists have uncovered evidence that a naturally occurring protein suppresses the growth of cancerous tumors, most likely through its control of a molecule involved in supplying blood to tumors. The research suggests that the protein, known as thrombospondin-1 (TSP1), holds promise as a tumor-suppressing treatment, the study's lead author told Reuters Health. ``Our body has several regulatory mechanisms in place to block cancer progression,'' Dr. M. Luisa Iruela-Arispe, of the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles, explained. Scientists have suspected that TSP1 inhibits angiogenesis, the process by which tumors form vessels to supply themselves with blood. Since tumors cannot survive without an adequate blood supply, researchers have been testing compounds that block angiogenesis to see whether they can stop or even reverse tumor growth. In an article that will be published in the October 23rd issue of the journal Proceedings of the National Academy of Sciences, Iruela-Arispe and her colleagues report proof that TSP1 suppresses tumors. The researchers compared a strain of mice with breast cancer that were genetically engineered to have excess levels of TSP1 with another strain that did not have any TSP1. Mice that lacked TSP1 had more tumors and wider and more numerous tumor-supplying vessels than expected. In contrast, mice that had high levels of TSP1 had fewer tumors. They also had fewer, narrower blood vessels. Iruela-Arispe and her colleagues also found that mice with no TSP1 had higher levels of a blood vessel growth factor as well as increased levels of a molecule called MMP9. Further testing suggested that TSP1's effects on MMP9 might account for its tumor-suppressing abilities. In laboratory experiments, the researchers found that TSP1 suppressed the activity of MMP9, which encourages angiogenesis and helps tumors spread to other organs, or metastasize. Based on the findings, Iruela-Arispe concluded that TSP1 ''is likely to be a good candidate for suppression of angiogenesis in tumors.'' SOURCE: Proceedings of the National Academy of Sciences 2001;98:12485- Reference Source 89 For more information on how to prevent other diseases, use PreventDisease.com's "Quick Prevention Resources".