NANOG protein, a
transcription factor expressed in embryonic stem cells, is overexpressed in
tumor development. Although studies investigating the function of NANOG in
cancer have shown that it plays several roles, such as in cell proliferation, invasion and
metastasis, the overall function of NANOG in
cancer cells has remained elusive. In the present study, NANOG expression in
oral squamous cell carcinoma (OSCC) was examined to determine its potential clinical significance. The expression of
NANOG protein was assessed in 60 patients with OSCC by immunohistochemistry, and its correlation with clinicopathological factors and
metastasis was evaluated.
NANOG protein levels in human OSCC cell lines were determined by western blotting and immunofluorescence staining.
NANOG protein expression was identified in 52 cases (86.7%) and expression levels were higher in primary foci of poorly differentiated OSCC than in those of well-differentiated OSCC, indicating that NANOG expression is associated with OSCC differentiation. Regardless of the differentiation levels of primary foci, NANOG expression levels in metastatic foci were extremely high. In addition, NANOG expression in metastatic foci was maintained at high levels following preoperative adjuvant
therapy. Furthermore,
NANOG protein was detected at an identical level in human OSCC cell lines. These data indicate that NANOG-expressing OSCC cells tend to metastasize and that metastatic
tumors expressing NANOG may be resistant to preoperative adjuvant
therapy, including chemoradiation. Thus, assessment of NANOG expression may assist the strategy for treatment of OSCC
metastasis.