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Autres Nouvelles
| MicroRNA Can Reign in Cancer Stem Cells |
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| Cancer Stem Cell | |||
| Vendredi, 04 Janvier 2008 08:00 | |||
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There are no translations available. Source : Ivanhoe By Ivanhoe Newswire Researchers have found a way to grow large numbers of human breast cancer stem cells in mice and they’ve discovered a genetic switch that regulates important properties of those cells. Tumor stem cells are mutations that live indefinitely. They can seed new tumors and are now suspected of causing many, if not all, cancers. They are not killed by chemotherapy or other current treatments. Their survival might explain why tumors recur or spread after treatment. But these tumor stem cells are rare so studying them has been difficult. MicroRNAs are important regulators of cell differentiation. The study shows that the microRNA’s push the stem cells to become more differentiated and less tumorigenic through its ability to switch off particular genes. By showing that microRNAs can rein in tumor stem cells, the study suggests the possibility of treating cancer with therapeutic RNA. The senior investigators are Judy Lieberman, Immune Disease Institute and Harvard Medical School professor of pediatrics at Children’s Hospital Boston and Erwei Song, a breast cancer surgeon at SunYat Sen University in Guangzhou, China. Song and first author Kenyan Yu isolated breast cancer cells from freshly removed tumors. They used tumors from women who had received chemotherapy treatment predicting that because stem cells are resistant to chemotherapy, the tumors of treated women would be rich in stem cells. They then set out to create large numbers of tumor stem cells by growing them in immunosurpressed mice dosed with a chemotherapeutic agent. In 3 months, 75 percent of the cells in the retrieved tumors had the properties of stem cells. With an ample supply of cells to work with, the researchers were able to measure the levels of RNAs. They found that the cancer stem cells had low amounts of several microRNA’s compared to more mature tumor cells or stem cells that had differentiated in culture. The researchers found that when they activated one of the microRNA’s called let-7, the stem cells, they lost their ability to self renew and began to differentiate. If the finding holds true for other tumors, let-7 may offer a unique opportunity to attack tumor stem cells using therapeutic RNA. “One of the fundamental problems of all the therapies that we have is that they are not doing anything to these cells,” says Lieberman. “If those turn out to be the cells that go on and form metastases and are resistant to chemotherapy and are responsible for relapse, and if your therapy isn’t dealing with those cells and is in fact selecting for them, that that is very worrisome.”
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| Mise à jour le Samedi, 05 Janvier 2008 23:52 |