Alteration of hexosaminidase isozymes in human renal carcinoma

The activity and isozyme patterns of hexosaminidase in human renal carcinoma were studied in comparison with those of normal kidney. Hexosaminidase in extracts from normal kidney and renal carcinoma tissue could be separated into two major forms [hexosaminidase A (Hex A) and hexosaminidase B (Hex B)] by Cellogel electrophoresis or by diethylaminoethyl cellulose column chromatography. All of 10 renal carcinoma tissues showed a low activity ratio of Hex A to Hex B, as compared with the ratio in normal kidney; the ratio in renal carcinoma tissue was between 0.61 and 2.21 (mean, 1.30), while that in normal kidney was between 2.50 and 4.52 (mean, 3.46). Hexosaminidase activity and the ratio of Hex A to Hex B in renal carcinoma tissue were independent of the cell type and the differentiation grade of carcinoma tissue. Hex A and Hex B of renal carcinoma tissue differed from each other in physicochemical properties such as pH dependence of enzyme activity, thermostability, and Km's for two synthetic substrates, but each isozyme maintained its same physicochemical properties whether from normal or from carcinoma tissue. The isozyme patterns of cultured renal carcinoma cells and placenta were similar to those of the carcinoma tissue. The results presented here indicate that hexosaminidase isozymes in renal carcinoma tissue express at least oncoplacental patterns.