Abstract: PURPOSE: To investigate the correlation of increased expression of TLR4 with poor prognosis in patients with oral squamous cell carcinoma (OSCC), and discuss the potential mechanism of mTOR regulating proliferation and metastasis of OSCC through TLR4 signaling pathway. METHODS: Immunohistochemistry was used to detect the expression of TLR4 in the pathological sections of 50 patients with OSCC. OSCC cell lines CAL27 was pre-treated with inhibitor of mTOR (rapamycin), then stimulated with lipopolysaccharide (LPS), a TLR4 ligand. MTT was used to detect cell proliferation and transwell assay was used to detect migration of CAL27 cells. Western blot was performed to detect changes in NF-κB and MARK signaling pathway. The data were analyzed using SPSS 16.0 software package. RESULTS: Increased expression of TLR4 showed a significant correlation with poor prognosis in patients with OSCC (P<0.05). Rapamycin could inhibit cell proliferation and migration of CAL27 cells significantly after TLR4 was activated (P<0.01) .Rapamycin suppressed NF-κB and MARK signaling pathway through inhibiting TLR4 signaling pathway. CONCLUSIONS: mTOR can regulate the proliferation and metastasis of OSCC through TLR4 signaling pathway, TLR4 might be a new target for treatment of OSCC.

Key words: Toll like receptor-4, TLR4, mTOR, Oral squamous cell carcinoma, Proliferation, Metastasis