The zymogen prothrombin stimulates cell locomotion and calcium influx in murine osteosarcoma cells by different mechanism from thrombin

The coagulation system plays a role in tumor invasion and metastasis. Proth rombin was previously found to stimulate the motility of melanoma cells. We compared the effect of prothrombin and thrombin on cell motility, calcium influx and actin stress filament contraction in highly metastatic osteosarc oma LM8 cells. Prothrombin and thrombin stimulated chemotaxis and chemokine sis of LMS cells in a dose-dependent manner. Calcium influx was significant ly increased after stimulation with thrombin and prothrombin. Thrombin and prothrombin markedly stimulated actin contraction in LM8 cells. Hirudin inh ibited the effects of thrombin but not those of prothrombin. Prothrombin ap pears to stimulate cell locomotion, actin contraction, calcium influx in LM 8 cells by different mechanism from thrombin.