An in vitro model designed for studying the mechanism of oral squamous cell carcinomas invasion was developed using a specific culture matrix composed of a collagen gel combined with human fibroblasts. Five SCC cell lines cultured on collagen-only gels showed stratified growth. However, all five cell lines demonstrated invasion into the matrix when cultured on the fibroblast-incorporating collagen gels. Moreover, fibroblastconditioned medium was shown to promote the invasion of HSC-3 cells into the collagen gels. HSC-3 cells were examined for their ability to degrade collagen gels. HSC-3 cells showed enhanced matrix degradation when cultured on [3H]-labeled collagen gels with fibroblast feeder layers. These results suggest that fibroblasts may play an important role in the invasion of oral SCC cell lines in vitro.
Four cell lines newly established in our laboratory were tested in this assay system. These cell lines cultured on fibroblast-incorporating collagen gels expressed morphologic and biologic characteristics in vitro similar to those in vivo. This assay system therefore proved a reliable and sensitive model for analysis of the invasive behaviour of human SCC cells. The system also demonstrates potential as a guide to prognosis and treatment in the evaluation of oral cancer.