Influence of tumour necrosis factor alpha on epithelial-mesenchymal transition of oral cancer cells in co-culture with mesenchymal stromal cells

摘要

Tumour progression in head and neck squamous cell carcinoma (HNSCC) is influenced by the surrounding stroma and inflammatory cytokines such as tumour necrosis factor alpha (TNF-alpha). The aim of this study was to test the hypothesis that TNF-alpha modulates the interactions of HNSCC cell line PCI-13 and bone marrow mesenchymal stromal cells (BMSCs) and influences markers of epithelial-mesenchymal transition (EMT). Following induction with TNF-alpha, mono- and cocultures of BMSCs and the established HNSCC cell line PCI-13 were analyzed; protein expression of E-cadherin and vimentin and qRT-PCR expression of Snail, Twist, MMP14, vimentin, E-cadherin, and beta-catenin were examined, and changes in cellular AKT signalling were analyzed. TNF-alpha induced a significant decrease in E-cadherin (64.5 +/- 6.0%, P = 0.002) and vimentin (10.4 +/- 3.5%, P = 0.04) protein expression in co-cultured PCI-13, while qRT-PCR showed a significant increase in beta b-catenin (BMSCs P < 0.0001; PCI-13 P = 0.0005) and Snail (BMSCs P = 0.009; PCI-13 P = 0.01). TNF-alpha also resulted in a down-regulation of AKT downstream targets S6 (38.7 +/- 20.9%, P = 0.01), p70S6 (16.7 +/- 12%, P = 0.05), RSK1 (23.6 +/- 28.8%, P = 0.02), and mTOR (27.4 +/- 17.5%, P = 0.004) in BMSC co-cultures. In summary, while reducing the expression of vimentin and AKT-signalling in PCI-13 and BMSC, respectively, TNF-alpha introduced an inflammatory-driven tumour-stroma transition, marked by an increased expression of markers of EMT.