Abstract
In recent years, accumulating evidence has appeared suggestive of the fact that platelets are deeply involved in the lodging of tumor cells during the process of bloodborne metastases. One of the most significant observations inferring a role for platelets in the development of metastases is that the abiility of certain tumor cells to form metastases is related to their ability to promote aggregation of host platelets.
In the present paper, attempts were made to characterize the platelet aggregating material obtained from established human cancer cell lines.
The following retults were obtained
1) The platelet aggregating activities of tumor cells (HMV-1, M7609) were diminished by treatments with trypsin but not with collagenase or neuraminidase. Aggregating activity was preserved with a preparation of membrane from these tumor cells, although it was abolished by heating (100°C 15min) or sonication.
2) The existence of divalent cation was required for the platelet aggregation induced by HMV-1 tumor cells.
3) By SDS PAGE (autoradiography), membrane proteins with MW of 10, 000-20, 000 daltons which specifically bound to platelets were commonly found in cells with platelet aggregating activity (HMV-1, M7609).
It was therefore, conculuded that platelet aggregation induced by human tumor cells is evoked by direct interaction of platelets with aggregating proteins (MW 10, 000-20, 000 daltons) on the cell membrane.
