Repopulating glioma cell lines

Cancer therapies target rapidly dividing cells, which is a problem if tumors contain slow-growing undifferentiated cells that act as stem cell for the malignancy, as accumulating evidence suggests. Now, Toru Kondo, Takao Setoguchi, and Tetsuya Taga (Kumamoto University, Japan, and University of Cambridge, Cambridge, UK) show that this problem may be widespread. They find that several cancer cell lines maintain a small proportion of self-renewing cells.

To search for these potentially dangerous cells, Kondo's team tested several cancer cell lines for the presence of side populations (SP) of cells containing the breast cancer–resistant protein 1 (BCRP1), an ATP-dependent transporter found in many stem cells. Of six lines tested, four had BCRP1-containing SP cells that accounted for between 0.4% and 2.1% of the total population.

The growth of SP cells requires basic fibroblast growth...