Activation of Notch signaling in human tongue carcinoma

BACKGROUND: Involvement of Notch signaling in several tumors is well known, but its role in tongue squamous cell carcinoma remains poorly characterized. The purpose of this study was to evaluate the roles of Notch signaling in the oncogenesis of tongue carcinoma. MATERIALS AND METHODS: Tumor specimens and adjacent non-neoplastic tongue tissues from 74 patients with tongue carcinoma and human tongue carcinoma cell line Tca8113 were examined using immunohistochemistry and RT-PCR to determine the expressions of Notch1, Notch3, Jagged1, and Jagged2. RESULTS: The mRNA expressions of Notch1, Notch3, Jagged1, and Jagged2 were detected in Tca8113, tongue carcinoma, and adjacent non-neoplastic tongue tissues. The expression levels of mRNAs in tongue carcinoma were higher than those in adjacent non-neoplastic tongue tissues (P < 0.05). Immunohistochemical examination showed that the Notch signal molecules were expressed in Tca8113, tongue carcinoma, and adjacent non-neoplastic tongue tissues. The expression rates of Notch1 and Notch3 protein in tongue carcinoma were higher than those in adjacent non-neoplastic tongue tissues (χ² = 6.10, P = 0.013; χ² = 3.94, P = 0.047). Notch1 and jagged1 were significantly more highly expressed in lymph node metastasis-positive tongue carcinoma (χ² = 6.108, P = 0.013; χ² = 7.354, P = 0.025). In addition, expressions of Notch3 and Jagged2 were highly correlated in tongue carcinoma tissues (χ² = 42.130, P < 0.001). CONCLUSIONS: Expressions of Notch receptors and ligands in tongue carcinoma and adjacent non-neoplastic tongue tissues suggest that Notch signaling may control cell differentiation and proliferation of carcinoma cells. The disorder of Notch signaling may be a mechanism of the tongue carcinoma development.