Analysis of proliferation and apoptosis, MUC-1 and Cdx-2 expression in distal colonic polyps

Abstract

Background. The universal molecular characteristics of malignancy are activation of cell proliferation and inactivation of apoptotic cell death. Besides genes-regulators of the processes other molecules are involved, including mucins and Cdx-2. Aim . To conduct comparative and correlation analysis of indexes of immunohistochemical expression of Ki-67, p53, caspase-3, as well as MUC-1 and Cdx-2 in distal colonic polyps. Methods. Pathohistological and immunohistochemical studies of biopsies of adenomas and hyperplastic polyps from 40 patients were carried out. Results. Distal colonic polyps are characterized by medium proliferation level: the median of Ki-67 expression for hyperplastic polyps is 42,20 (35,27; 52,38) %, while the median for adenomas is 65,39 (52,28; 76,23) % (р˂0,05). The polyps are characterized by low p53 expression levels: the median of the marker expression for hyperplastic polyps is 1,53 (1,17; 3,16) %, for adenomas – 9,15 (8,26; 12,39) % (р˂0,05). The studied polyps are characterized by low apoptosis levels: the median of caspase-3 expression for hyperplastic polyps is 33,78 (30,28; 42,34) CUOD, for adenomas – 22,19 (16,84; 40,51) CUOD (р˂0,05). Distal colonic polyps are characterized by medium MUC-1 and Cdx-2 expression levels: the medians of the markers expression for hyperplastic polyps are 62,13 (34,20; 71,85) CUOD and 71,81 (62,36; 77,77) CUOD, for adenomas – 80,25 (52,14; 95,21) CUOD and 95,14 (81,19; 112,17) CUOD, respectively (р˂0,05). The correlation analysis revealed several correlations: reverse medium strength correlation between p53 and caspase-3 expression levels (r = -0,57, р˂0,05), direct medium strength correlation between caspase-3 and MUC-1 expression levels (r = 0,52, p˂0,05) take place in hyperplastic polyps, whereas reverse strong correlation between caspase-3 and MUC-1 expression levels 1 (r = -0,88, p˂0,05) takes place in adenomas. Conclusions. Distal colonic adenomas differ by higher proliferation and p53 expression levels, comparing to hyperplastic polyps, and by lower apoptosis level that is associated with higher MUC-1 expression level as well. Hyperplastic polyps differ by higher apoptosis level that is associated with lower MUC-1 expression level. Cdx-2 expression increases on benign adenoma stage and does not correlate with proliferation and apoptosis indexes.