Early membrane alterations in isolated cells treated in vitro with chemical carcinogens.

Membrane alterations were detected in isolated epithelial cells treated in vitro with 5 x 10(-4) M dibutylnitrosamine (DBN) or 1.2 x 10(-9) M diethylstilbestrol (DES) for 30 min. Addition of DBN to bladder cells and DES to endometrial cells elicited a striking increment in Con A-mediated hemadsorption, but not Con A binding, to the treated cells as compared to those not treated with carcinogens. Concomitantly, release of the lysosomal proteinase, cathepsin B1, to the extracellular medium was essentially doubled in the preparations exposed to the carcinogens, as compared to corresponding controls. The increased cellular hemagglutination in response to carcinogen treatment was significantly reduced by prior incubation of the epithelial cells with ovomucoid, a proteinase inhibitor that suppresses the activity of cathepsin B1.