beta-Hexosaminidase from colon and sera of dukes-classified colorectal cancer patients: activity levels, isozyme patterns, and kinetic properties

Abstract

Total activity levels, isozyme patterns, and kinetic properties of beta-hexosaminidase were studied in crude supernatants of malignant and adjacent, uninvolved normal colon tissues and in sera from 28 Dukes-classified colorectal cancer patients. A significant increase (P less than .001) in both beta-hexosaminidase activity and beta-hexosaminidase specific activity and a significant increase (P less than .01) in the relative percentage of activity comprised by the basic thermostable form of beta-hexosaminidase (Hex B) isozyme were found in malignant tissue compared to the activities seen in uninvolved normal colon tissue. No apparent correlations were found between either beta-hexosaminidase activity levels or relative percentage of Hex B and Dukes category. Kinetic analysis indicated that the thermolabile form of beta-hexosaminidase and Hex B from malignant colon were comparable to the corresponding isozymes from normal colon with regard to thermostability after preincubation at 50 degrees C and pH activity curves (optimum between pH 4.0 and 5.0). Significantly decreased (P less than .05) beta-hexosaminidase activity was found in sera of the 28 colorectal cancer patients (17.3 +/- 5.2 U/ml, mean +/- SD) when compared to the activity in 19 controls with nonmalignant diseases (21.4 +/- 8.2 U/ml) and 17 normal controls (21.3 +/- 6.4 U/ml). Isoelectric focusing indicated that a peak of beta-hexosaminidase activity with an isoelectric point value (9.5) comparable to that of the peak found in increased amounts in malignant colon was detectable in the sera of 36% of the colorectal cancer patients and 11% of the controls.