Association of α_vβ₃ integrin expression with the metastatic potential and migratory and chemotactic ability of human osteosarcoma cells

Introduction. Expression of adhesion molecules such as α _v β ₃ integrin has been associated with the metastatic potential of tumor cells. The purpose of this study was to determine whether α _v β ₃ expression correlated with the metastatic potential of human osteosarcoma cells. Materials and methods. We developed a series of sublines (LM2-LM7) from human osteosarcoma SAOS parental cells, with progressively increasing potential to form lung metastases in nude mice after intravenous injection. SAOS parental and LM2 cells were poorly metastatic, but LM7 cells resulted in visible metastatic lung nodules by 6-8 weeks. We quantified α _v β ₃ integrin expression using flow cytometry. Results. α _v β ₃ expression correlated with the metastatic potential of the cells, with LM7 cells showing the highest expression. LM7 cell adhesion to vitronectin decreased after treatment with echistatin, a RGD-containing peptide antagonist of α _v β ₃. LM7 cells demonstrated higher chemotactic activity than SAOS cells to a homogenate made from lung tissue. This chemotactic activity was also inhibited by echistatin. These data indicated that α _v β ₃ was critical for the migration of LM7 cells to the lung homogenate. Chemotaxis to a liver homogenate was the same for LM7 and SAOS cells. Migration of LM7 cells through lung endothelial cells was higher than that through liver endothelial cells, and echistatin again inhibited this migration. Conclusions. α _v β ₃ integrin expression may play a role in the metastatic potential of osteosarcoma cells by enhancing the ability of the cells to migrate specifically to the lung. α _v β ₃ integrin may therefore be a potential new target for osteosarcoma.