New chemical attacks tumor-fueling cancer cells

By Sheilah Downey (sheilahd@foodconsumer.org) 

The discovery of a new chemical to attack the aggressive stem cells in breast cancer -- thought to be resposible for spreading tumors -- may lead to new types of anti-cancer therapies, say scientists at the Whitehead and Broad Institutes.

The research team discovered a chemical, called salinomycin, that works in mice to kill stem cells in breast cancers that have the ability to seed new tumors. Stem cells, which scientists said are hard to find and anaylze because of their elusive properties, are the cause of cancer re-emergence.

"Many therapies kill the bulk of a tumor only to see it regrow," says Eric Lander, director of the Broad Institute of MIT and Harvard, an co-author of the study in Cell. "This raises the prospect of new kinds of anti-cancer therapies."

Researchers believe that tumors, including breast, prostate and colon, harbor cells with the ability to regenerate cancers. These cancer stem cells are also resistant to current cancer therapies, said scientists.

Salinomycin kills not only laboratory-created cancer stem cells, wrote researchers, but also naturally occurring ones. When compared to paclitaxel, a common treatment for breast cancer, the new compound reduced the number of cancer stem cells by more than 100-fold. It also diminished the breast tumor growth in mice.

Previous studies in breast cancer patients revealed groups of genes that
were linked with aggressive tumors and pointed towards poorer prognosis.

Treatment with salinomycin, showed the study, can decrease the activity of these genes.

"Our work reveals the biological effects of targeting cancer stem cells," said co-author Piyush Gupta. "Moreover, it suggests a general approach to finding novel anti-cancer therapies that can be applied to any solid tumor maintained by cancer stem cells."

The study appears in the Aug. 13 advance online issue of Cell.