"In our model, all these cells can form tumors," he said. "And they're phenotypically different from each other not because they're hierarchically organized but because they're just turning these surface markers on and off."
The U-M team found that all tumor-forming melanoma cells gave rise to progeny with a variety of marker patterns, and that all of those sub-populations retained the ability to form tumors. The marker changes appeared to be reversible, rather than being associated with a transition from tumor-forming to non-tumor-forming states, as the cancer stem cell model would predict.
The Cancer Cell paper follows up on work reported by the Morrison lab in the Dec. 4, 2008, edition of the journal Nature. The Nature article demonstrated that tumor-forming melanoma cells are not rare, as predicted by the cancer stem cell model. The researchers determined that at least one-quarter of melanoma cells have the ability to form new tumors.
Melanoma kills more than 8,000 Americans each year. The human melanoma cells used in this study were provided---with the patients' permission---from the U-M's Multidisciplinary Melanoma Program, one of the country's largest melanoma programs and part of the U-M Comprehensive Cancer Center.
"These new findings significantly advance our understanding of melanoma," said cutaneous oncologist Dr. Timothy Johnson, director of the U-M melanoma program and a co-author of the Cancer Cell paper.
"This type of groundbreaking discovery achieves our core objective of combining clinical studies with laboratory research to develop new and better treatments for optimal patient care," Johnson said.
|Contact: Jim Erickson|
University of Michigan