RARE but pernicious cancer 鈥渟tem鈥� cells, blamed for the spread and invincibility of some tumours, may be more vulnerable than we thought.
The suggestion is that a small number of such cells within tumours may be the precursors to the other cancer cells in those tumours. The stem cells may also be resistant to ordinary cancer drugs, causing the cancer to recur.
To hunt for drugs that target these cells, Piyush Gupta, a molecular biologist at the Broad Institute at the , and colleagues genetically engineered ordinary human cells so that they acquired some of the properties of cancer stem cells, including being impervious to chemotherapy.
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Next they tested thousands of different compounds for their ability to kill these reprogrammed cells. One called salinomycin stood out because it killed the reprogrammed cells, but not healthy cells, and was easy to obtain in large quantities. When Gupta鈥檚 team added salinomycin to cultured human breast-cancer cells, it was about 100 times as effective at killing the cancer stem cells as popular anti-cancer drug, paclitaxel. What鈥檚 more, mice injected with human breast-cancer cells developed fewer aggressive tumours when treated with salinomycin compared with paclitaxel (Cell, ).
Little is known about the drug鈥檚 safety, or whether it would find its way through the human bloodstream to tumours. But it does prove that cancer stem cells aren鈥檛 invincible, Gupta says.