Scientists discover first compound that specifically kills cancer stem cells

In collaboration with the Press Association

US scientists have discovered a compound that targets and destroys cancer stem cells, a type of rare cell that some scientists believe are responsible for driving tumour growth, and that appear to be resistant to existing anti-cancer therapies.

Researchers at the Massachusetts Institute of Technology (MIT) and the Broad Institute used a new "high-throughput" screening method that allowed them to test thousands of compounds and identify those that killed cancer stem cells.

Their screen revealed 32 possible compounds which were able to kill cancer stem cells but not other cancer cells. The results are published in the journal Cell.

One compound in particular, called salinomycin, was found to reduce the proportion of breast cancer stem cells by more than 100-fold compared to paclitaxel, a chemotherapy drug used to treat breast cancer.

Tumour samples that were treated with salinomycin were less able to start tumour growth when injected into mice, and the compound also slowed down the growth of existing tumours.

Further research revealed that salinomycin decreases the activity of certain genes that have previously been shown to be highly active in breast cancer stem cells, and are associated with particularly aggressive tumours and a poor outcome.

The discovery of the compound could pave the way for the development of new therapies that target cancer stem cells.

Study author Robert Weinberg, of the Whitehead Institute for Biomedical Research in Massachusetts, said: "Evidence is accumulating rapidly that cancer stem cells are responsible for the aggressive powers of many tumours.

"The ability to generate such cells in the laboratory, together with the powerful techniques available at the Broad Institute, made it possible to identify this chemical.

"There surely will be dozens of others with similar properties found over the next several years.

"Accordingly, future therapies could offer greater possibilities for individualised treatment by considering both the genetic alterations and differentiation states present within the cancer cells of a tumour at the time of diagnosis."

Dr John Stingl, group leader in mammary stem cell biology at Cancer Research UK's Cambridge Research Institute, said: "This is one of the biggest advances we have seen this year in this area of research. These scientists have demonstrated that it's possible to selectively target the rare cancer stem cells that drive tumour growth.

"This research also introduces a completely new way of identifying cancer drugs. The challenge for the future is to bring this class of drugs to the clinic and to identify the patients that are likely to respond to them."

Dr Kat Arney, Cancer Research UK's senior science information officer, added: "Finding ways to target cancer stem cells is a vital part of efforts to beat cancer. This is an important piece of research, as it reveals a way to test for chemicals that can act on stem cells, as well as highlighting a potential new cancer drug.

"But at the moment, this work is still at an early stage, and there are a number of technical hurdles to be overcome before we know if the findings can be applied to patients with breast cancer."

References

Gupta, P., Onder, T., Jiang, G., Tao, K., Kuperwasser, C., Weinberg, R., & Lander, E. (2009). Identification of Selective Inhibitors of Cancer Stem Cells by High-Throughput Screening Cell DOI: 10.1016/j.cell.2009.06.034