Effect of cisplatin on the plasma membrane phosphatase activities in ascites sarcoma-180 cells: a cytochemical study

To study the effects of cisplatin [cis-dichlorodiammine-platinum (II)] on tumor cells in the presence or absence of the immune system, animals with ascites sarcoma-180 tumor burden were treated with therapeutic dose levels (9 mg/kg). Similarly, ascites sarcoma-180 cells were maintained in tissue culture media containing the same levels of the drug. Cell samples were taken from the animals at 12-hr intervals for 3 days, whereas samples were drawn from the tissue cultures at 15-, 30-, 45-, and 60-min and at 2-, 3-, 4-, and 5-hr intervals. Treated and untreated cells from in vitro and in vivo experiments, when checked for alkaline phosphatase, 5'-nucleotidase, Ca2+-ATPase, and Na+-K+-ATPase, show a gradual decrease in activity on the plasma membrane. It takes about 60 min for inactivation of any enzyme in vitro, whereas it takes 2 days in in vivo experiments. Quantitative analysis show alkaline phosphatase activity drops from 9.7 to 4.9 nmol in just 15 min, and drops further to 0.79 nmol after 2 hr. Inactivation of various plasma membrane enzymes, resulting in permeability changes, is probably responsible for cell death.