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Monday, November 20, 2006To see if stem cells were at the root of colorectal cancer, Dick's team began by taking samples of tumours surgically removed from patients' large intestines or other areas of the body where the cancer had spread. They broke the tumours down into individual cells, then implanted "millions and millions" of them into the capsule surrounding the kidney of each laboratory mouse. In all, 17 mice were implanted - and all 17 developed tumours, said Dick, explaining that the immune-deficient mice lack disease-fighting cells, so cancer can grow unchecked. .....Through painstaking work transplanting various numbers of tumour cells into mice, the scientists initially determined that colon cancer stem cells are rare - occurring at a rate of about one in 60,000 cells. They then narrowed the search even further by testing the cells for the presence or absence of CD133, a protein on the surface of some cells, which has been implicated in some other types of cancer, among them brain and breast. When the different cells were implanted in mice, only some of the animals got tumours. "What we showed was we basically never got a tumour when we transplanted the CD133-negative cells," said Dick. "And all of the mice that were transplanted with CD133-positive cells gave us tumours." The researchers also found that the new tumours were comprised of both positive and negative CD133 cells, proving that both types originated from the initial transplanted cell. In other words, the scientists had isolated colon cancer stem cells, which act as the seeds from which the cancer grows. And they discovered they are actually rarer than initially thought, making up just one in every 250 cells in a malignant growth in the large intestine. Not that anyone's looking to clone cancer, but being finding ways to target those stem cells for destruction could lead to a cure for cancer. posted by Sydney on 11/20/2006 09:46:00 PM 0 comments 0 Comments: |
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