Weill Cornell team identifies new cancer stem cell driving metasta...( NEW YORK (May 27 2008) -- The molecu...),Health

NEW YORK (May 27, 2008) -- The molecular profile of cancer stem cells that initiate metastatic colon tumors is significantly different from those responsible for primary tumors, according to new research from a team at Weill Cornell Medical College.

Cancer researchers have long believed that a protein called CD133 identifies a population of cancer stem cells (so-called CD133+ cells), the only subset of cells that are responsible for tumor initiation. But in the experiment, in which immunocompromised mice were injected with human metastatic colon cancer, the Weill Cornell team discovered that cancer cells that do not express CD133 can also spur metastatic disease.

"In fact, metastatic tumors originating with these CD133- cells are more aggressive than those spurred by CD133+ cells," says study senior author Dr. Shahin Rafii, the Arthur B. Belfer Professor in Genetic Medicine and director of the Ansary Center for Stem Cell Therapeutics at Weill Cornell. Dr. Rafii is also a noted investigator at the Howard Hughes Medical Institute. "Our discovery shows that metastatic and primary cancer may not initiate in the same way. This could have significant implications for research going forward -- we believe the discovery opens up new avenues of investigation in cancer stem cell biology."

The findings were released as a special "highlighted" article in the May 22 online edition of the Journal of Clinical Investigation.

Cancer stem cells are a small, discrete class of cells that scientists believe give rise to malignancy and are solely responsible for tumor maintenance. For years, experts have tracked expression of the CD133 protein as a means of identifying a population of tumor-initiating cells.

To understand the biology of CD133+ cells in a healthy state and during tumor formation the researchers generated a transgenic mouse in which the CD133 gene is replaced with a reporter gene called lacZ. "We relied on the expression o
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