Objective: The objective of this study was to further investigate the communication between OSCC cells and fibroblasts, specifically to determine whether activated fibroblasts can influence the expression of a key marker of OSCC behaviour, the β6 integrin receptor subunit.
Methods: Normal human oral fibroblasts were obtained with ethical permission and incubated with transforming growth factor-β (5 ng/ml) for 24 hours in serum free medium. Expression of alpha smooth muscle actin (αSMA) was used as a marker of activation and was determined using fluorescence microscopy and qRTPCR. Conditioned fibroblast medium was collected and the OSCC cell line SCC4 exposed to this for a further 24 hour period followed by RNA extraction and qRTPCR for β6 gene expression.
Results: Exposure of fibroblasts to TGF-β resulted in a marked increase in αSMA gene expression of 16.5 +/- 9 fold after 24 hours indicating that these cells were ‘activatable’ and that the TGF-β was functionally active. Incubation of SCC4 cells with supernatant from these cells resulted in a 5.2 +/- 3 fold increase in β6 gene expression compared to non-activated supernatants. The addition of TGF-β directly to SCC4 cells did not increase β6 gene expression indicating that activated fibroblasts release a mediator or mediators responsible for this effect.
Conclusion: Fibroblasts activated with TGF-β can enhance expression of the β6 integrin on OSCC cells. As the β6 integrin is known to be neo-expressed in OSCC and mediates a number of pro-tumourigenic properties, knowledge of factors that control its expression may represent pathways that can be specifically targeted in anti-stromal cancer therapies.