The expression profile of Oct4 and Sox2 in the carcinogenesis of oral mucosa

This study is to detect the co-expression of embryonic stem cell-related markers (Oct4 and Sox2) in the carcinogenesis of oral mucosa. The expression profile of these markers was studied by immunohistochemistry assay in rat and human samples. The normal oral mucosa (20 cases) and the transforming oral mucosa (20 cases) were performed in rat samples. The precancerous lesions (20 cases), OSCCs in primary site (116 cases), corresponding epithelial non-cancer tissues adjacent to the OSCC (20 cases) and 46 paired metastatic OSCCs in lymph nodes were performed in human samples. The co-expression of the two markers was defined as both of them are positively detected in the same site of one case under one selected field of microscope. The results indicated that Oct4 and Sox2 were individually detected in normal oral mucosa, but they cannot be co-expressed in the same site of one case. The co-expression of Oct4 and Sox2 (Oct4⁺Sox2⁺) was frequently detected in the transforming oral mucosa of rat (16/20), precancerous lesions of human (12/20) and epithelial non-cancer tissues adjacent to the OSCC (18/20). Also, Oct4⁺Sox2⁺ profile was remarkable noted in the primary sites of OSCCs (38/116). In the 46 paired OSCCs (primary sites with lymph node metastasis), Oct4⁺Sox2⁺ profile (8/46) was less frequently detected than Oct4^low/-Sox2^low/- (14/46) profile in the metastatic sites. To conclude, this study suggests Oct4 and Sox2 are expressed in normal oral mucosa, premalignant diseases, primary sites of OSCCs and metastasis sites of OSCCs. Oct4⁺Sox2⁺ profile may contribute to the malignant transformation of oral mucosa.