About 90 percent of cancer deaths are caused by tumors that have spread from their original locations. This process, known as metastasis, requires cancer cells to break loose from their neighbors and from the supportive scaffold that gives tissues their structure. MIT cancer biologists have now discovered that certain proteins in this structure, known as the extracellular matrix, help cancer cells make their escape. The researchers identified dozens of proteins that surround highly metastatic tumors, but not less aggressive tumors, and found that four of those proteins are critical to metastasis. The findings could lead to new tests that predict which tumors are most likely to metastasize, and may also help to identify new therapeutic targets for metastatic tumors, which are extremely difficult to treat. “The problem is, all the current drugs are targeted to primary tumors. Once a metastasis appears, in many cases, there’s nothing you can do about it,” says Dr. Richard Hynes, leader of the research team and a member of MIT’s Koch Institute for Integrative Cancer Research. “In principle, one could imagine interfering with some of these extracellular proteins and blocking metastasis in a patient. We’re a long way from that, but it’s not inconceivable.” Koch Institute postdoc Dr. Alexandra Naba is the lead author of the study, which appears in the March 11 online edition of the journal eLife. Other authors are Dr. Steven Carr, director of the Proteomics Platform at the Broad Institute; Dr. Karl Clauser, a research scientist at the Broad Institute; and Dr. John Lamar, a research scientist at the Koch Institute. The extracellular matrix is made mostly of collagens, proteins that provide structural support for living tissues.
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