Identification of {alpha}v{beta}6-positive stem cells in oral squamous cell carcinoma.

Oral squamous cell carcinoma (SCC) is composed of a heterogeneous population of cells which range anywhere from epithelial to mesenchymal in phenotype. Several oral cancer specimens with antibodies to TRA160, a marker of pluripotent cells, were screened. Compared with the well differentiated lesions, pluripotent cells were more numerous in specimens from poorly differentiated tumors. In vitro, the expression of TRA160 was much greater in invasive oral SCC9beta6 cells compared with the poorly invasive SCC9SN or SCC9beta6D1 cells, which express a truncated beta6. In vitro, pluripotent cells were instrumental in aggressively closing an experimental wound assay. Lastly, TRA-1-60+/beta6+ tumor cells which formed vascular-like structures in vivo were identified. SCC9beta6 cells formed interconnecting channels, whereas SCC9SN cells did not in an in vitro Matrigel angiogenesis assay. The results of this study clearly demonstrated the differential distribution of pluripotent stem cells in oral SCC and that the beta6 integrin may be an important regulatory component of the pluripotent phenotype.