New Chemical Kills Cancer Stem Cells
Persistence pays off: after searching through more than 16,000 chemical compounds, scientists discovered one that selectively kills cancer stem cells within breast cancers in mice. These cancer stem cells are believed to enable cancers to spread (metastasize) and to return after seemingly successful cancer treatment.
The scientists noted that their discovery of this potent chemical, called salinomycin, shows that it is possible to find chemicals that destroy cancer stem cells. Salinomycin destroyed not only cancer stem cells created in the laboratory, which the researchers were able to do in this study, but also naturally occurring cells.
The creation of cancer stem cells alone was an achievement. Although scientists have recognized the importance of these cells in promoting tumor growth and regenerating cancers, they have not been easy to study. That’s because cancer stem cells are relatively scarce compared to other tumor cells, and they also tend to lose their stem cell-like properties when they are grown in a laboratory.
To make the cancer stem cells they needed, the investigators applied novel reagents that they developed to a technique called epithelial-to-mesenchymal transition. This technique prompts adult cells to go through a transformation that changes their shape and motility. During this transitional phase, the cells take on properties similar to stem cells.
Once the scientists had a large supply of cancer stem cells, they began testing thousands of chemicals until they found just the right one that kills them effectively. Compared to paclitaxel (Taxol®), a commonly prescribed chemotherapeutic drug for breast cancer and ovarian cancer, salinomycin reduced the number of cancer stem cells by more than 100-fold. The compound was also able to reduce breast tumor growth in mice.
Salinomycin also appears to have other cancer-fighting qualities. Upon further study, the researchers discovered that the chemical can reduce the activity of genes in breast cancer that are highly active in cancer stem cells. Paclitaxel treatment was not able to produce the same effect.
It is still too early to know whether salinomycin will destroy cancer stem cells in humans as it does in mice. Further studies are also needed to determine how salinomycin works. At least now scientists have a way to produce the cancer stem cells they need to conduct this necessary research.
Science Daily 8/13/09
US News & World Report 8/13/09