Invadopodia formation in oral squamous cell carcinoma: The role of epidermal growth factor receptor signalling

Objective: Invadopodia are actin-rich structures that are formed on the ventral membrane of the cell and degrade extracellular matrix (ECM) by accumulation of matrix metalloproteinase (MMP). Consequently, understanding how invadopodia form and function should facilitate the identification of new therapeutic target for anti-invadopodia therapy. The present study was designed to investigate invadopodia formation associated with oral squamous cell carcinoma (OSCC) and the effect of epidermal growth factor receptor (EGFR) signalling on invadopodia formation and ECM degradation activity. Design: Immunofluorescence analysis of invadopodia formation and ECM degradation was performed using confocal microscope. To understand the role of EGFR signalling, cells were treated with AG1478 or PD153035 (EGF receptor tyrosine kinase inhibitors) and assessed using zymography and an ECM degradation assay. Results: Invadopodia containing dot-shaped F-actin were observed in stress fibres of HSC-3 OSCC along with evidence of ECM degradation activity. GM6001, a broad range of MMP inhibitor impaired matrix degradation and gelatinolytic activity of active MMP-2. AG1478 and PD153035 inhibited invadopodia formation and ECM degradation activity, as well as gelatinolytic activity of proMMP-9 and proMMP-2. Conclusions: We provide evidence that HSC-3 OSCC has a tendency to adopt invadopodia for invasion and accompanying MMP-dependent proteolytic ECM degradation and EGFR signalling is necessary for invadopodia formation and associated ECM degradation activity.