Current cancer stem cell theory holds that tumors are comprised of a variety of cell types. Among them is a small subset of rather primitive cells that, like other stem cells in the body, are self-sustaining, self-renewing and multipotent, or capable of creating other types of cells and tissues. These cells are different from normal stem cells, however, in that injecting even as few as 100 of them into laboratory animals will cause cancer. Scientists have dubbed these cancer stem cells.
Cancer stem cells were first identified in leukemia, but they have also been found in breast, brain, colon and prostate cancers. Because they are rather unstable, they are notoriously tricky to isolate and describe. They are also resistant to virtually any kind of treatment, and some scientists believe they are the reason cancer recurs. Until now, no one has known how they arise.
But a team of scientists, led by Dr. Jian-Xin Gao, a researcher in the department of pathology at Ohio State University Medical Center, has identified a new set of cells he calls precancerous stem cells (pCSCs).
These cells share some of the characteristics full-fledged cancer stem cells have, but they are different in that they respond to distinct cell signals that determine their ultimate fate ?whether they will continue to grow into cancer or cancer stem cells, lie inactive or be eradicated by the body’s immune system.
"These hybrid cells are very complex. They have properties of normal and abnormal stem cells, and do not always lead to cancer ?only so
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Source:Public Library of Science