Cytokinetic behavior of Ehrlich ascites tumor after in vivo treatment with cis-diamminedichloroplatinum(II) and metallocene dichlorides.

The influence of an in vivo treatment with optimally tumor-inhibiting doses of cis-diamminedichloroplatinum(II) (DDP), titanocene dichloride (TDC), and vanadocene dichloride (VDC) on the DNA distribution pattern, determined by pulse-cytophotometry, and on the mitotic activity of EAT cells is investigated. Whereas DDP causes an immediate and long-lasting decrease of mitoses but no disturbances of the EAT cell kinetics, a marked G2 block with a maximum at 10-12 h a. t. and an irreversible and extensive mitotic depression is evoked by TDC. In the case of DDP and TDC, the tumor cells are removed several days a. t. by cells belonging to the defensive system of the host animals. In contrast, VDC induces partially synchronized waves after a transient suppression of mitoses and reversible cell accumulation in the late S and in the G2 phases. Additionally, 5-16% of the cells become polyploid after VDC treatment.