Isoenzymes A and B of N-acetyl-β-D-hexosaminidase in tissue of colon cancer

Introduction: It is anticipated that in Poland, colon cancer in 2025 will affect approximately 15 500 men and 9100 women. It is estimated that the number of deaths from colorectal cancer will almost double in the male population and increase by about 1/3 in women. In removing tissues damaged by cancer a role is played by N-acetyl-β-D-hexosaminidase (HEX), which is the most active of lysosomal exoglycosidases removing sugar residues from the non-reducing end of oligosaccharide chains of glycoconjugates (glycolipids, glycoproteins and proteoglycans). Activity of HEX may be useful for diagnosis and reducing the incidence of colorectal cancer.

Aim: To evaluate the activity of HEX, HEX A and B in tumour tissues and macroscopically unchanged parts of the colon.

Material and methods: For analysis portions of colon cancer tissue with the degree of cell maturity G2 were obtained from 17 patients aged 39 to 82 years (68.39 ±11.34 years) diagnosed with adenocarcinoma (n = 15) and mucinous adenocarcinoma (n = 2), as well as colon tissue fragments collected from the same patients from locations distant (5 cm) from the tumour (n = 15) constituting the control. The activity of HEX and its isoenzymes A and B in the tissues was determined spectrophotometrically by the method of Marciniak et al. Protein concentration was determined by the method of Lowry et al.

Results: Tissues of colorectal cancer, compared to control tissue of the macroscopically unchanged colon, showed a significant increase in the activity of HEX and its isoenzymes A and B. Based on Duke’s classification there was found a significant increase in activity of HEX B in tissue of colorectal tumours of class A, B and C and the activity of HEX and HEX A in the tissue of colon tumours of class C, in comparison to the unchanged colon tissue. HEX B shows a significantly higher activity in the tumours of colorectal cancer class A as compared to class B.

Conclusions: Colorectal cancer increases glycoconjugate catabolism in comparison to remote colon tissue, reflected by a significant increase in the activity of HEX and its isoenzymes A and B in the tissue of colorectal cancer, as compared to controls. In the early stages of colorectal cancer mainly catabolism of neutral glycoconjugates increases, reflected by a significant increase in HEX B activity, as compared to control, and in carcinomas of class A in comparison to class B according to Duke's classification.