Time-Dependent Changes in Drug Sensitivity Expressed by Mammalian Cells After Exposure to Trypsin 1.2

ABSTRACT-Immediately aHer a 5-mlnute exposure to 0.025% trypsin, Chinese hamster ovary cells treated with anticancer drugs exhibited changes In drug sensitivity. Depending on the drug, cells Immediately became more sensitive, less sensitive, or showed no change In sensitivity at all. The deviation from normally expected survival values ranged from fourfold to flHy-fold and varied with time (of drug treatment) after trypsinization. By the 12th hour post trypsinization, the drug survival respons.. had returned to values obtained with untrypslnlzed cells.-JNCI 64: 913-916, 1980. Inasmuch as the clinically useful antitumor agents appear to act within the cell, the transport of such agents across cell membranes becomes an important parameter. Cell surface and plasma membrane proteins have been shown to increase in quantity as cell