foreign invasion.
aggressive breast cancer cells (fluorescent spots) have spread in the lung of a mouse.
Li Ma / Whitehead Institute
A new study has found that a small molecule can trigger breast cancer cells to go on a rampage invasive. The molecule could be a potential target for new therapies.
Small pieces of RNA called microRNAs help control gene activity and orchestrate the development of plants and animals ( Science NOW, July 8, 02). But these essential molecules can also turn bad: Some of them apparently cause cancer. How they do it is poorly understood, although recent studies have suggested that many microRNAs come from regions of the human genome associated with cancer risk.
A team led by researcher Robert Weinberg cancer of the Whitehead Institute in Cambridge, Massachusetts, has undertaken to monitor the involvement of microRNAs in the spread, or metastasis, cells cancer of the breast. In a screen of 29 microRNAs previously implicated in breast cancer, the team identified one - called miR-10b - that was prevalent in a line of human breast cancer cells very aggressive, but not in sedentary tumor cells. When the researchers blocked the action of miR-10b, the invasiveness of these cells decreased by 10 times. And when scientists introduced miR-10b in a culture of non-metastatic breast cancer cells, they became very invasive, as measured by their ability to migrate through a filter in a layer of target cells.
The team then implanted miR -10B-making cells in the breast area of young female mice. After 6 weeks, the cells began to spread to distant tissues such as the lungs; non-metastatic cells, however, have caused breast tumors but not spread. Finally, the researchers traced the genetic pathways that influence the regulation and action of miR-10b. They found that the production of the molecule is under the control of a gene called Twist , which had been previously identified as a "master regulator" of embryonic development. In turn, miR-10b influences the expression of two genes involved in cell migration and cancer formation. The scientists report their findings online September 26 in Nature .
Weinberg and colleagues warn that despite the importance of miR-10b in triggering the spread of breast cancer cells, it is unclear whether their findings will lead to new therapies. "Although it is likely, we can not yet conclude that targeting miR-10b will reverse metastasis," says lead author of the paper, Whitehead cancer researcher Li Ma. But other scientists are more optimistic. "The work was carried out impeccably," says developmental biologist and pioneer in research of microRNA Frank Slack of Yale University. "The therapeutic potential is huge ... and very interesting pursuit." Carlo Croce, a cancer geneticist at Ohio State University in Columbus, agrees that the results "are very important and can be a potentially important target for treatment."
related site
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