Significance of the TGF-β1/IL-6 axis in oral cancer

The aim of the present study was to explore specific molecular markers that could lead to new insights into the identification of innovative treatments in oral cancer. The role of TGF-β1 (transforming growth factor-β1) and its predictive power in the prognosis of oral cancer has been identified. Human oral cancer cell lines, including SCC4 and SCC25, were selected for cellular experiments. Changes in tumour aggressiveness, responses to treatment and the signalling pathway responsible were investigated in vitro. Furthermore, 125 oral cancer tissue specimens were constructed into tissue microarray blocks for immunohistochemical analysis to correlate the expression of TGF-β1 with clinical outcome. Using in vitro experiments, our results revealed that activated TGF-β1 signalling resulted in more aggressive tumour growth, augmented the epithelial–mesenchymal transition and more resistance to treatment. Activated IL-6 (interleukin-6) signalling could be the mechanism underlying the effects of TGF-β1 on oral cancer. Regarding clinical data, the incidence of TGF-β1 immunoreactivity in oral cancer specimens was significantly higher than in non-malignant epithelium and positively linked to IL-6 staining. Furthermore, expression of TGF-β1 was significantly correlated with the risk of lymph node involvement, disease recurrence and shorter survival in patients with pathological stage III–IV oral cancer. In conclusion, the TGF-β1/IL-6 axis had predictive power in the prognosis of oral cancer, and targeting TGF-β1 could represent a promising treatment strategy.