Influences of thrombin, factor XIII and fibronectin on the growth of tumor cells and leukemic cells in vitro.

Thrombin, factor XIII and fibronectin were incubated with cultures of mouse sarcoma cells, human cervix carcinoma cells (HeLa cells) and cells of an acute lymphoblastic leukemia. Thrombin induced a significant increase of 3H-thymidine uptake into cells with a 1,5- to 2-fold increase of cell count. The cells of an acute lymphoblastic leukemia showed a similar response to the influence of thrombin. Factor XIII merely induced an increase of 3H-thymidine uptake in tumor cells, the cell count remained constant. These results differ from experiments with cultures of normal fibroblasts. Decreased receptor density in tumor cells toward factor XIII and thrombin would play a role so that the mitogenic stimulus is impaired. The cells of an acute lymphoblastic leukemia showed under the influence of factor XIII a significant increase of cell count and thymidine uptake. HeLa cell growth was optimal at low fibronectin concentrations. Fibronectin concentrations of 1 mg/ml to 3 mg/ml inhibited HeLa- and mouse sarcoma cell growth.