The Mechanism Of TNF-α Promoting The Ability Of Invasion And Metastasis In Oral Squamous Cell Carcinoma

Tissue invasion and metastasis are one of the characteristics of tumor and closed to thefatality rate of oral squamous cell carcinoma (OSCC). A growing number of studiesconfirm that inflammation tumor microenvironment plays an important role in tumorinvasion and metastasis. Tumor necrosis factor-alpha (TNF-α) is one of the importantinflammatory cytokines, which can induce epithelial-mesenchymal transition (EMT) incontinuous low doses and promote the invasion and metastasis in many tumors. However,the impact on OSCC and the mechanism underline still unclear.Objective: To explore the influence of TNF-α in inducing EMT and promoting theinvasion and metastasis on OSCC.Methods: In our study, three oral squamous cancer cells（SCC4、SCC9and SCC25) aredivided into the experimental group (TNF-αstimulated) and the control group (withoutTNF-αstimulated) respectively. First, we use real-time RT-PCR, western blot andimmunofluorescence microscopy to detect the changes of the exprssion of epithelial andmesenchymal markers. Meanwhile, the expression of transcription inhibitory factor werealso detected from the mRNA and protein level by real-time RT-PCR and westernblotting. Next, the expression of MMPs were evaluated by using real-time RT-PCR andwestern blotting to detect the role of TNF-α on three oral squamous cancer cells. Finally,wound-healing assay, flow cytometry cycle and transwell invasion assay were performed to measure the biological properties changes of three oral cancer cells before and afterTNF-α stimulated.Results: First, TNF-α induced three OSCC cells (SCC4、SCC9and SCC25) to undergoneEMT with the down-regulation of E-cadherin and the up-regulation of vimentin, and theirmorphology changed into a fibroblast-like phenotype. We further demonstrated thatTNF-α increased both the mRNA level and the protein lever of Snail. In addition, theexpression of MMP-2, MMP-9,MMP-13and MMP-14of SCC4were increased afterTNF-α stimulated, the level of MMP-9and MMP-14of SCC9regulated by TNF-α, andthe expression of MMP-9,MMP-13and MMP-14of SCC25also activated by TNF-α.The most important of all, the migratory and invasive activities of three OSCC cells wereincreased after TNF-α treatment.Conclusion: On the one hand, our study indicates that TNF-α can induce an EMT byoverexpression of the transcriptional repressor Snail and promote the invasion andmetastasis in three OSCC cells (SCC4、SCC9and SCC25). On the other hand, TNF-α canup-regulate the expression of MMP-2, MMP-9,MMP-13and MMP-14, which alsopromote the migratory and invasive properties of three OSCC cells.