Stem cell markers as predictors of oral cancer invasion.

We previously showed that within primary tumors there exist subpopulations of cells expressing stem cell markers. Using immunofluorescence and western blotting, we examined the expression of stem cell markers tumor-rejection antigen 1-60 (TRA1-60) and octamer-binding transcription factor 3/ 4 (OCT3/4) to determine their relationship with cell invasiveness. Six human oral cancer cell lines were examined and a direct correlation was found between expression of these stem cell markers and invasion. Poor expression of E-cadherin and increased expression of N-cadherin was also found in TRA1-60- and OCT3/4- expressing cells. Phosphorylation of the major signaling molecule mitogen activated protein kinase (MAPK) was greatest in the TRA1-60- and OCT3/4- expressing cells. These results suggest that expression of specific stem cell markers in tumors may help guide a clinician's choice of treatment.