Effect of Extracellular matrix (ECM) on motility of oral cells

Progression to cancer occurs within epithelial cells that rest on a basement membrane composed of extracellular matrix (ECM). We hypothesize that progression of oral epithelial cells is modulated by the microenvironment/ECM, and we expect the ECM to evolve during carcinogenesis. We have found that growth of oral cells on ECM-coated dishes induced an increase in alpha-6 integrin expression, as measured by flow cytometry. This plasticity in integrin expression could affect the biology of progression. Objective: To determine if increased alpha-6 expression correlated with altered cell motility. Methods: Primary cultures of normal oral epithelial cells and a cell line established from dysplasia are plated on ECM-coated coverslips (10µg/ml) and cultured for 48 hrs. The cells are then examined with time-lapse video microscopy. Images are captured every 10 min. Cells are tracked by tracing their position every hour for up to 8 hrs and cell track length is measured with image analysis (Simple PCI®). For cells which remained in the field but did not divide, a rate (µm/hr) is obtained. Results: With fibronectin, a statistical significant increase in motility was observed (P<0.05; Control-30.8µm/hr, n=102 cells; Fibronectin-38.2µm/hr, n-101 cells). A plot of cell number vs rate also showed that the control histogram was skewed towards cells with lower rates while with fibronectin coating the distribution was skewed towards higher rates. However, a low number of cells, control and fibronectin, showed rates that were greater than 4 times the average indicating individual cellular heterogeneity. Conclusions: As a population, growth on ECM-coated dishes affected cell motility. Altered motility may affect the biology of premalignant lesions. This work was supported by a Johnson and Johnson AADR Fellowship and by NIH grant DE14395.