by Roberta Nichols and Alicia Di Rado
 

Nearly one out of five breast cancer patients has triple-negative breast cancer — an aggressive type of tumor that often returns despite treatment. Spreading early, this cancer frequently defies conventional therapies, and researchers think they know the culprit: breast cancer stem cells.

George Somlo conducts collaborative studies of breast cancer stem cells. (Photo by p.cunningham)

Modern breast cancer treatments target receptors found on the surface of breast cancer cells. Triple-negative breast cancers have none of those receptors, so they are not amenable to such therapies. But they may resist other drugs, too, because they might have a higher concentration of chemotherapy-defying breast cancer stem cells.

“Cancer stem cells have the ability to regenerate themselves and to develop into mature tumor cells,” said George Somlo, M.D., co-director of City of Hope’s Breast Cancer Program. “They also have an uncanny ability to survive chemotherapy and radiation, allowing them to spread to other parts of the body.”

These stem cells are the target for a longstanding, productive research project between Somlo, director of breast oncology and high-dose therapeutics in the Department of Medical Oncology & Therapeutics Research, and Michael Clarke, M.D., associate director of the Stanford Institute for Stem Cell & Regenerative Medicine. The work recently earned a five-year, $2.7 million grant from the National Institutes of Health.

The grant enables the collaborators to focus particularly on triple-negative breast cancers in different ethnic groups. They will study the characteristics of different types of breast cancer cells, and cancer cells in general, comparing them to normal breast tissue. The cells come from City of Hope patients treated through various clinical trials led by Somlo and colleagues.

The City of Hope-Stanford collaborators published findings in the Oct. 4, 2010, issue of the Proceedings of the National Academy of Sciences. They described a method of following the spread of cancer stem cells by tagging the cells with special genes that can be detected optically through noninvasive imaging.

Now, using a novel single-gene expression analysis technology developed by Stanford University physicist and mathematician Steven Quake, Ph.D., and applied in Clarke’s lab, the investigators will initially characterize breast cancer stem cells among African-Americans, who have a higher prevalence of triple-negative breast cancer than other ethnicities.

The investigators hope to identify signaling pathways that can then be targeted by more effective therapies — work that could have far-reaching implications.

“Once we characterize the breast cancer stem cell population in African-American breast cancer patients, we’ll look for any differences among ethnicities,” Somlo said. “Eventually, we hope to use the knowledge gained to develop new technology that can help us create new and more personalized treatment for patients.”