Head and Neck Cancer Stem Cell Research
How were the cancer stem cells discovered?In 2007, a team of scientists from the U-M Comprehensive Cancer Center and Stanford University led by Mark Prince analyzed cells from head and neck tumors removed from seven patients. They looked for cell surface markers previously found in breast cancer stem cells. Another team of scientists at the U-M Cancer Center discovered in 2004 that breast cancer stem cells had three specific surface markers. When U-M and Stanford scientists looked for the CD44 marker, they found it on a small number of cells in head and neck cancer tumors, also.
Then the scientists injected cells from these tumors into mice with deficient immune systems. Mice injected with CD44-positive tumor cells developed tumors that were identical to the patient's original tumor, while mice given CD44-negative cells did not form tumors. This indicated that cells with the CD44 marker included stem cells for head and neck cancer. Scientists are looking for other markers to help them find the pure population of cancer stem cells within the CD44-positive group.
Were the stem cells in a specific location in these tumors?Cancer stem cells were located in the basal, or bottom, layer of skin or mucosal cells lining the mouth and throat. This is important, because cells divide and produce new replacement cells in this cell layer. Because normal stem cells are found in the basal layer, it's significant that cancer stem cells were found there, also. It suggests that cancer stem cells probably originate from normal mucosal stem cells in the basal layer and then gain mutations, which makes them behave abnormally.