Effect of different platelet agonists on intracellular free CA++ concentrations in human tumor cells: Possible role in tumor growth

✍ Scribed by Anna Saporiti; Alessandra Brocchieri; Camillo Porta; Mauro Moroni; Guido Grignani

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: French
• Weight: 687 KB
• Volume: 62
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910620310

✦ Synopsis

Modulation of cytoplasmic

Ca" concentration is a mechanism common to signal transduction pathways regulating many cellular phenomena, including the interactions of tumors with the hemostatic system. We have investigated the pro-aggregating and pro-coagulant activities of human tumor cell lines cultured in vitro and the ability of different platelet agonists to induce Ca transients in these cells. Cells of a malignant mesothelioma line activated platelets by a thrombin-dependent mechanism; on the contrary, HeLa cells, derived from a uterine cervical cancer, possessed ADP-dependent pro-aggregating activity, and DND-I A melanoma cells did not stimulate platelet aggregation. All cell lines showed a tissue-factor-like procoagulant property, more pronounced in mesothelioma cells. Furthermore, ADP was able to induce a transient increase in cytoplasmic Ca--concentration in tumor cells from all lines; collagen showed this effect in mesothelioma cells and in HeLa cells, and thrombin was effective only in mesothelioma cells. PAF never induced Ca++ fluxes in any of the cell lines investigated. Finally, the calcium-channel blocker verapamil inhibited agonist-induced Ca-+ transients in tumor cells and in vitro tumor-cell growth. These data may help to identify new possible mechanisms of the 2-way interaction of tumors with the hemostatic system.