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Researchers Uncover Colon Cancer Stem Cells


Scientists have found that a small number of stem cells appears to be responsible for the growth of colon cancer. Stem cells are master cells that can be coaxed to grow into any tissue in the body. But in the case of some cancers, small numbers of stem cells might be the reason why some tumors grow out of control. VOA's Jessica Berman reports.

Experts say no matter how aggressively they are treated with chemotherapy, some cancers seem to come back. These include breast cancer, leukemia and brain cancer.

John Dick of the University of Toronto says researchers have wanted to find out if a similar mechanism is at work with cancer of the colon, which is a leading cause of cancer death in many parts of the world.

"It's critically important because the reality is that despite the therapies that we have available today, still a great number of people who have colon cancer relapse, which means that our therapies are not completely effective," said John Dick.

In paper published in the journal Nature, Dick and colleagues describe their work with a stem cell marker, or protein, called CD133 in colon cancer. CD133 had previously been implicated in prostate and brain cancers.

Only a very small number of colon cancer cells - one in 250 - is rich in CD133.

Dick's researchers discovered that when they injected human colon cancer cells high in CD133 into mice, the tumors flourished, while cells with small amounts of CD133 hardly budged.

A separate paper published in Nature supports the idea that only a very small number of colon cancer cells is responsible for tumor growth.

Ruggero de Maria of Rome's Instituto Superiore di Sanita says he and colleagues are treating cancer cells with high levels of CD133.

"We have cells growing for almost two years now in culture, and they are able to reproduce the same tumor very similar to the tumor from the patients from which we derived these cells," said Ruggero de Maria.

Both De Maria and the University of Toronto's John Dick were interviewed by the editors of Nature.

Before there's talk of a cure, Dick says, researchers need to find out what makes cancers aggressive. He says hopefully, the latest discoveries will help find the answer.

"Leukemia stem cells really spend a lot of their time lying dormant," he said. "And it explains why those cells could be swimming in a sea of chemotherapy agents and they would survive and then would be responsible for growth back. We need to determine what the growth properties are for these colon cancer initiating cells."

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