title: Characterization of the platelet-aggregating activity of tumor cells.
abstract: Two lines of mouse tumor cells were shown to be capable of aggregating mouse and rabbit platelets in vitro. This process required higher Mg2+ concentrations than were needed by other commonly used platelet-aggregating agents. Platelet-aggregating activity was also found in tumor cell membrane fragments. This membrane-bound platelet-aggregating material contained protein, lipid, and carbohydrate moieties. The presence of all three appeared to be essential for stimulating platelet aggregation. Destruction of any component abolished its activity: protein by trypsin; lipid by phospholipase A2 and non-ionic detergents; and sialic acid by neuraminidase. Platelet aggregation induced by tumor cell membrane fragments was associated with a secretory release reaction. In this process, growth-promoting activity for tumor cells was also released from platelets. These results underline the importance of platelets in establishing tumor metastases.
mesh_terms: D000230:Adenocarcinoma / Q000097:blood; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D006133:Growth Substances / Q000097:blood; D006629:Hirudins / Q000494:pharmacology; D066298:In Vitro Techniques; D007680:Kidney Neoplasms / Q000097:blood; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D009374:Neoplasms, Experimental / Q000097:blood*; D009447:Neuroblastoma / Q000097:blood; D010974:Platelet Aggregation / Q000187:drug effects; D011817:Rabbits
chemical_list: D006133:Growth Substances; D006629:Hirudins; D000244:Adenosine Diphosphate; D008274:Magnesium; D001241:Aspirin