| Summary: | 碩士 === 國立中山大學 === 生物科學系研究所 === 102 === In Taiwan, oral cancer is the 4th leading cause of cancer death for males and the top common cancer in young adult males. The most common subsites of oral cancer are the tongue and buccal mucosa in Taiwan. Cancer stem cells (CSCs) have been implicated in tumorigenesis and prognosis. Reprogramming factors employed to induce pluripotent stem cells are associated with CSCs formation. The purpose of this study was to investigate the relationship of the protein expression levels of three reprogramming factors, Octamer-binding Protein 4 (Oct4), Sex-determining Region Y (SRY)-related Box 2 (Sox2), and Nanog, with the tumorigenesis, clinicopathological outcomes and survival in oral tongue SCC and buccal mucosal SCC. Expression levels of Oct4, Sox2, and Nanog were evaluated by immunohistochemistry using tissue microarray slides. We compare the expression levels of the Oct4, Sox2, Nanog-N, and Nanog-C in normal, tumor adjacent normal, and tumor tissues by subsites of oral tongue and buccal mucosa. The expression levels of both Oct4 and Sox2 in oral tongue SCC and buccal mucosal SCC were significantly lower than those in the tumor adjacent normal tissue or normal tissue, except that for Oct4 in buccal mucosal SCC. However, the expression level of Nanog-C in oral tongue SCC and buccal mucosal SCC was significantly higher than those in the tumor adjacent normal tissue and normal tissue. Our IHC results showed that the median expression levels of Oct4, Sox2, Nanog-N, and Nanog-C were 40, 2.50, 0, and 90 in 248 oral tongue SCC specimens, respectively. In addition, the median expression levels of Oct4, Sox2, Nanog-N, and Nanog-C were 73.75, 4.75, 0, and 63.75 in 188 buccal mucosal SCC specimens, respectively. The expression levels of Oct4, Sox2, and Nanog-C gradually decreased when tumor progressed from early stage and advanced stage (AJCC pathological stage, T stage, or N stage). After adjustment of clinicopathologic outcomes, our results showed a significant association between the elevated Sox2 expression and prolonged disease-specific survival in oral tongue SCC. In conclusion, Oct4, Sox2, and Nanog-C could be biomarkers for tumorigenesis in both oral tongue SCC and buccal mucosal SCC, except for Oct4 in buccal mucosal SCC. Additionally, Sox2 might be a prognostic biomarker for oral tongue SCC.
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