• 3/27/2007
  • web-based article
  • staff
  • Journal of the American Dental Assoc, Vol 138, No 3, 296

Researchers have identified a marker on head and neck tumor cells that indicates which cells are capable of promoting the cancer’s growth. The finding, which appeared in the Jan. 16 issue of the Proceedings of the National Academy of Sciences, is the first evidence of cancer stem cells in head and neck tumors.
Researchers at the University of Michigan Comprehensive Cancer Center, Ann Arbor, and Stanford University School of Medicine, Stanford, Calif., took tumor samples from patients undergoing surgery for head and neck squamous cell carcinoma, including cancers of the tongue, larynx, throat and sinus. They separated cells from the samples according to whether they expressed a marker on their surface called CD44. They then implanted the sorted cells into immune-deficient mice to grow tumors.

The cells that expressed CD44 were able to grow new tumors, while the cells that did not express CD44 were not. Researchers found that the tumors that grew were identical to the original tumors and contained cells that expressed CD44, as well as cells that did not. This ability to both self-renew and produce different types of cells is a hallmark of stem cells.

The percentage of cells within a tumor expressing CD44 varied from one sample to the next, with one sample having as high as 40 percent of these cells. Studies in other cancer types have found the stem cell population to be less than 5 percent.

“The CD44-positive cells contain the tumorigenic cells, but we don’t think that’s a pure population of cancer stem cells,” said lead author Mark Prince, MD, assistant professor of otolaryngology, University of Michigan Medical School, and section chief of otolaryngology, VA Ann Arbor Healthcare System. “We still need to drill down further to find the sub-population of those cells that is the pure version.”