Regulation of tumorigenesis in oral epithelial cells by defined reprogramming factors Oct4 and Sox2

Oct4 and Sox2 are pluripotent stem cell factors but the interplay between them in tumorigenesis is unclear. The aim of the present study was to investigate the roles of Oct4 and Sox2 in the reprogramming of oral cancer stem cells. One or both Oct4 and Sox2 were overexpressed in immortalized oral epithelial (hTERT(+)-OME) cells by lentivirus transduction. In addition, Oct4 and Sox2 proteins in two oral squamous cell carcinoma cell (OSCC) lines (Cal27 and primary cultured OSCC from a T2N2M0 patient) were individually or combinedly knocked down by shRNA. The results showed that the doubly transduced (Oct4(+)Sox2(+)) cells could trigger neoplasms in immunodeficient mice after lentivirus transduction, but single transduced (Oct4(+) or Sox2(+)) cells had no tumor formation ability. The knockdown Sox2(low) and knockdown Oct4(low)Sox2(low) cells resulted in decreased tumor size in the immunodeficient mice but the single knockdown Oct4(low) cancer cells acquired more aggressive xenografts. Our findings suggest that Oct4(+)Sox2(+) cells may be reprogrammed cancer stem cells inducing oral carcinogenesis.