Catalase immunoexpression in colorectal lesions

Abstract

Introduction: It is generally accepted that the gastrointestinal tract, and especially the colon, is constantly exposed to reactive oxygen species (ROS) that may be responsible for the appearance of genetic mutations. To keep a steady-state control over ROS production-detoxification, organisms have evolved a defensive system. Nevertheless, many reports have described decreased level of antioxidant enzymes, especially catalase (CAT), in cancer tissues.

Aim: In this work we try to assess the immunohistochemical expression of CAT protein in colorectal adenoma and adenocarcinoma samples.

Material and methods: This study was performed on resected specimens obtained from 122 patients who had undergone surgical resection for colorectal cancer, and from 120 patients who had undergone colonoscopy. Paraffin- embedded, 4 µm-thick tissue sections were stained for rabbit polyclonal anti CAT antibody obtained from GeneTex (cat. no. GTX110704).

Results: In adenoma strong immunoexpression was detected mainly in infiltrating mononuclear cells within lamina propria. High expression of CAT was significantly associated with grade of dysplasia (high grade vs. low grade, p = 0.037). In adenocarcinoma samples, the high level of CAT immunoexpression was significantly correlated with histological grade of tumour (G1 vs. G2 vs. G3, p = 0.001) and depth of invasion (T1 vs. T2 vs. T3 vs. T4, p = 0.003).

Conclusions: Development of colorectal cancer is associated with increased expression of CAT in the stage of adenoma and decreased expression in the stage of adenocarcinoma.

Keywords: antioxidants; catalase; colorectal cancer; oxidative stress; reactive oxygen species.

Figure 1

Immunoexpression of catalase (CAT) in colorectal adenomas and adenocarcinomas. A – CAT immunoexpression in cells of lamina propria (red arrows), fibroblast-like cells around the crypts (black arrows) and walls of blood vessels (arrowhead) in healthy colorectal tissue. B, C – CAT immunoexpression in samples of tubular adenomas with low-grade dysplasia. Positive reaction was detected in cells of lamina propria (red arrows) and fibroblast-like cells around the crypts (black arrows). CAT immunoreactivity was also demonstrated in apical parts of the crypts (arrowhead). D – CAT immunoexpression in tubule- villous adenomas with high grade of dysplasia was demonstrated in cells of lamina propria (red arrows) and apical parts of the crypts (arrowhead)