A chemical that works in mice to kill the rare, but aggressive, cells within breast that have the ability to seed new tumors, has been discovered by an Indian-origin researcher in Boston.
Piyush Gupta, a researcher at the Broad Institute, points out that these cells, known as cancer stem cells, are thought to enable cancers to spread and to re-emerge after seemingly successful treatment.
Revealing the study's findings in a research paper, published in the advanced online edition of the journal Cell, he said that it might be possible to find chemicals that selectively kill cancer stem cells.
Robert Weinberg, a Member of Whitehead Institute for Biomedical Research who jointly wrote the study report with Gupta, said: "Evidence is accumulating rapidly that cancer stem cells are responsible for the aggressive powers of many tumors. 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."
Eric Lander, Director of the Broad Institute of MIT and Harvard, and an author of the Cell paper, added: "Many therapies kill the bulk of a tumor only to see it regrow. This raises the prospect of new kinds of anti-cancer therapies."
Tumors are thought to harbor a group of cells that have the unique ability to regenerate cancers, and are largely resistant to current cancer therapies.
If it were possible to identify chemicals that selectively kill cancer stem cells, according to the researchers, such chemicals might become critical candidates for future drug development.
For their study, the researchers first used a recently developed method to generate large numbers of cancer cells with stem cell-like qualities in the lab, and then undertook a large-scale analysis of thousands of chemical compounds, applying automated methods to search for ones with activity against breast cancer stem cells.
From a pool of more than 30 promising candidates, the researchers identified a compound with surprising potency.
The compound, called salinomycin, kills not only lab-created cancer stem cells, but also naturally occurring ones.
Compared to a common chemotherapeutic drug prescribed for breast cancer called paclitaxel, salinomycin reduced the number of cancer stem cells by more than 100-fold. It was also found to diminish breast tumor growth in mice.
The researchers have also found that salinomycin treatment can decrease the activity of the genes that are highly active in cancer stem cells, showing a possible molecular basis for the chemical's biological effects.
"Our work reveals the biological effects of targeting cancer stem cells. 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," says co-first author Piyush Gupta, a researcher at the Broad Institute.
He, however, warns that it is too early to say whether cancer patients will benefit from salinomycin treatment.
He says that more studies are required to determine exactly how salinomycin works to kill cancer stem cells, and if it can wield the same tumor-reducing power in humans as it does in mice.
Gupta points out that such analyzes generally take several years to complete.