Distal colonic polyps: immunohistochemical study of proliferation and apoptosis

Abstract

Background. It’s well known that colonic polyps can be precursors of colorectal cancer. But exact immunohistochemical parameters, including proliferation and apoptosis levels of polyps’ cells, that may have prognostic value, still not known. Objective. To study the features of immunohistochemical expression of proliferation and apoptosis markers by distal colonic polyps’ cells. Methods. Pathomorphological and immunohistochemical studies of biopsies of distal colonic polyps from 30 patients (the age ranged from 41 to 83 years) were carried out. Results. Distal colonic polyps are characterized by the medium proliferation level of epithelial cells [Me=62.40% (48.65; 76.23) for adenomas, Me=26.23% (22.19; 48.88) for hyperplastic polyps], the low proliferation level of stromal cells [Me=2.94% (1.23; 4.35) for adenomas, Me=1.18% (1.10; 1.86) for hyperplastic polyps], the low p53 expression level of epithelial and stromal cells [Me=2.39% (1.58; 8.26) and Me=1.23% (0.72; 1.49) for adenomas’ cells, Me=0,00% (0,00; 1,47) and Me=0,00% (0,00; 0,05) for hyperplastic polyps’ cells], and also by the low apoptosis level of epithelial and stromal cells [Me=31.84CUOD (19.53; 42.34) and Me=43.87CUOD (25.47; 73.09) for adenomas, Me=16.99CUOD (11.86; 39.85) and Me=28.64CUOD (19.20; 30.71) for hyperplastic polyps]. There are direct correlations between the expression levels of proliferation and apoptosis markers and also the dysplasia grade of the distal colonic adenomas: between the Ki-67 expression levels of epithelial and stromal cells and also the dysplasia grade (γ=0.65 and γ=0.70, respectively), between the p53 expression level of epithelial cells and the dysplasia grade (γ=0.53), between the caspase-3 expression levels of epithelial and stromal cells and also the dysplasia grade (γ=0.80 and γ=0.63, respectively). Moreover, there are direct correlations between the expression levels of proliferation and apoptosis markers of distal colonic polyps’ epitheliocytes: between the Ki-67 and p53 expression levels (r=0.71 for adenomas, r=0.79 for hyperplastic polyps), between the Ki-67 and caspase-3 expression levels (r=0.61 for adenomas), between the p53 and caspase-3 expression levels (r=0.59 for adenomas, r=0.79 for hyperplastic polyps). Conclusion. These data indicate the close association between the processes of proliferation, accumulation of p53 protein, and apoptosis of the distal colonic polyps’ cells.