Factors affecting the growth of head and neck squamous carcinoma cell lines.

Cell plating density influences the growth pattern of human squamous cell carcinoma (SCC) cell lines in culture. SCC lines were used to study factors responsible for these effects. Experiments in which the medium was changed daily or in which conditioned medium was used showed that the growth-supporting factors were not found in the media. However, when cells were plated in dishes in which the same cell line had been grown to confluence and removed by scraping, logarithmic growth began immediately. The effect was not seen on areas of the plate that had been covered with coverslips or in dishes where fibroblasts had been cultured. Antibodies to fibronectin, laminin, and a variety of epidermal cell antigens were used to determine the nature of the growth-stimulating substances remaining on the dish following cell removal. Results indicate that an extracellular matrix with similarities to basement membranes was present on the conditioned dishes.