Platelet Aggregation Induced by Adenosine Diphosphate Released from Cloned Murine Fibrosarcoma Cells Is Positively Correlated with the Experimental Metastatic Potential of the Cells

We established five clones (ML‐01, ML‐02, MH‐01, MH‐02, MH‐03) from murine 3‐methylcholan‐threne‐induced fibrosarcoma A (Meth A), and investigated their experimental metastatic potentials in relation to their platelet‐aggregating activities. A clone with a high metastatic potential (MH‐02) showed a characteristic biphasic pattern of platelet aggregation, of which the first peak was not present in the aggregation patterns of the clone with low metastatic potential (ML‐01). The first peak was eliminated by treatment of the cells with apyrase, indicating that adenosine diphosphate (ADD was the causative substance of this particular peak. The metastatic potential of clones correlated well with the ADP concentration of the culture media. These results suggest that the increased ADP production and consequential enhancement of platelet‐aggregating activity are closely related to the increment of pulmonary metastatic potential of MH‐02 clone.