When they did this, researchers found that the ALDEFLUOR-positive cells acted like stem cells, while the ALDEFLUOR-negative cells did not. Stem cells are defined by their ability to generate identical cells as well as to differentiate into other types of cells.
The study also tested whether the separated cells could produce a breast tumor. Tumors formed only from the ALDEFLUOR-positive cells, even when as few as 500 cells were used. On the other hand, 50,000 ALDEFLUOR-negative cells did not generate tumors.
In addition to identifying the stem cells, the researchers found ALDH1 can indicate how aggressive a tumor is. In tissue samples from 577 patients with breast cancer, those bearing ALDH1-positive tumors had lower overall survival and were 1.76 times more likely to develop metastases than patients with ALDH1-negative tumors. ALDH1 was expressed in 19 percent to 30 percent of the tumors.
The ALDH1 marker correlates with more aggressive tumors, possibly reflecting a different rate of renewal of cancer stem cells in these cancers. Its possible to use ALDH1 in association with other markers as a prognostic marker to help determine what treatment is necessary. More research is needed, though, before we can apply these findings in the clinic, Dontu says.
While this work was done specifically in breast cancer, the researchers believe it could have implications for other cancer types. U-M researchers are actively involved in stem cell research in virtually all cancer types. In addition to the initial breast cancer stem cell discovery, U-M researchers have been the first to identify stem cells in pancreatic and head and neck cancers. Work is ongoing to develop and test treatments that target these cells.
The lessons weve learned from breast cance
|Contact: Nicole Fawcett|
University of Michigan Health System