The research, published in the October 2005 issue of Tissue and Cell, is the first to examine the highly specialized microenvironment, termed the stem cell niche, which surrounds adult stem cells, and its role in breast cancer development. These niches are key regulators of stem cell activity in mammary tissue, and defects that develop in these groups of cells can give rise to breast cancer.

"This study helps us understand adult stem cells differently than we previously did. Particularly, when looking for the causes of breast cancer, we must take into account the stem cell as well as the environment that surrounds it," said Robert Dickson, Ph.D., co-author of the paper and co-director of the breast cancer program at the Lombardi Comprehensive Cancer Center.

The study used genetically engineered mice as models of ductal or lobular breast cancer that is caused by overproduction of certain proteins. These proteins (c-Myc and TGF-alpha) exist naturally in the body, but when produced in excess in mammary tissue cells, breast cancer can develop.

Gloria Chepko, Ph.D., a postdoctoral fellow and the paper's lead author, built on previous research results that demonstrated the existence of five different types of cells in normal breast tissue. Two of the cell types are stem cell-like and give rise to the other three. For the present study, she devised a method to identify all the cell types at low magnification, allowing more cells to be counted. This method revealed not only that each cell population has a different size in normal breast tissue, but also that the different cells are arranged in particular relationships to each other. The arrangements form repeating units called stem cell niches and provide nest-lik
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Contact: Liz McDonald
eem6@georgetown.edu
202-687-5100
Georgetown University Medical Center
4-Oct-2005