Histochemical and cytochemical study of butyrylcholinesterase activity in rat hepatocellular carcinomas induced by 3'-methyl-4-dimethylaminoazobenzene.

The activity of butyrylcholinesterase (BCHE), a liver fetal isozyme (Zone L-V) of a nonspecific esterase, was studied histochemically and cytochemically in rat hepatocellular carcinomas induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). In normal adult rats, BCHE activity was very prominent in cells of the intestinal mucosa but was not detectable in the liver. On the other hand, in fetal rat liver, a few cells scattered throughout the organ were BCHE positive. 3'-Me-DAB induced poorly differentiated hepatocellular carcinomas showing an intense BCHE activity, especially in areas consisting of small tumoral cells proliferating in a sheet-like pattern. Surrounding noncancerous liver tissue was completely devoid of reaction products. Less-differentiated trabecular hepatocellular carcinomas also showed a positive reaction. On the other hand, well-differentiated hepatocellular carcinoma and hepatocellular carcinoma with an adenomatous pattern were barely stained, while areas of cholangiofibrosis were usually negative. Thus, in confirmation of a previous report, BCHE appears to be a positive marker of poorly differentiated hepatocellular carcinomas induced by 3'-Me-DAB. By electron microscopy, reaction products were demonstrated in the cisternae of the endoplasmic reticulum, in the nuclear envelopes, and sometimes on the cell surface of undifferentiated tumoral cells. The significance of the appearance of BCHE activity in hepatocellular carcinomas induced by 3'-Me-DAB is discussed.