Although a growing body of evidence seems to support the cancer stem cell hypothesis, melanoma has remained a conundrum. A University of Michigan study in 2008 found that as many as one in four melanoma cells could cause cancers in immune compromised mice, suggesting that there may not be a particularly privileged subset of cancer stem cells in this tumor type. Boiko set out to solve the mystery.
"I didn't know if melanoma would in fact have the cancer-initiating cells," said Boiko. "I was completely unbiased, so I was actually sort of surprised to find such a clear-cut answer. It fits exactly what's been discovered in the studies of other solid tumors."
To conduct the study, Boiko analyzed cell surface markers on primary melanoma tumor samples taken directly from patients at the Stanford Cancer Center. In this way, he avoided having to grow the cells for a long period of time in the lab. Continuous culturing, or passage, of cancer cells often gives the cells time to evolve and change in ways that might not accurately reflect their composition in melanoma patients.
He found that one protein, called CD271, was always expressed on only a fraction of the cells in the human melanoma samples tested: The proportion of cells expressing CD271 varied in the samples from 2.5 to 41 percent of the total cell population; the marker appeared on a mean of 16.7 percent of cells in the samples.
This was interesting because CD271 was previously identified as a marker that identifies a group of cells called the n
|Contact: Krista Conger|
Stanford University Medical Center