Hot nanotubes blast chemo-resistant cancer cells into oblivion

When it comes to cancer cells, a particularly confounding breed called cancer stem cells have proven difficult to kill. Because they divide so slowly, chemo drugs do them little harm, and they appear resistant to heat therapies that are generally good at killing most cells. Some cancer drugs even appear to promote the growth of cancer stem cells.

Now, three years after they found that the heat from 30-second laser blasts can kill kidney cancer stem cells, researchers at Wake Forest Baptist Medical Center say the same treatment works to kill breast cancer stem cells as well.

Torti's team tested this photothermal therapy on mice, injecting tumors containing breast cancer stem cells with nanotubes that in and of themselves have no anti-tumor properties. When exposed to 30 seconds of laser light from outside the body, however, those nanotubes vibrated and produced sufficient heat to stop the growth of the entire tumor bulk, including the cancer stem cells.

"[Cancer stem cells] are tough," says lead investigator and biochemistry professor Suzy V. Torti. "The advantage of the nanotube approach is that in addition to eliminating the tumor bulk, it would get rid of the stem cells, so presumably these tumors would be less likely to recur than tumors that were treated with something else, like drugs or radiation."

Torti says that while this study only validates this new type of therapy on breast cancer specifically, it may work on other types of cancer stem cells as well. Many questions about how the heat kills the cells remain, however, and she says it will probably take a good five to 10 years of further study before they can investigate the therapy in human clinical trials.

For now, Torti says that the early success of this approach, detailed in the April 2012 issue of the journal Biomaterials, "gives us a direction to go for a cure." Maybe some day it could serve as a non-invasive alternative to surgically removing certain types of malignant tumors.