Comparative study of EpCAM expression in polyps and adenocarcinoma of the distal colon

Abstract

Annotation. ЕpCAM is known as a universal stem cell marker, however, the question of its value in colorectal cancerogenesis is still open. The aim of the research was to compare EpCAM immunohistochemical expression levels in polyps and adenocarcinoma of the distal colon. Pathohistological and immunohistochemical studies of biopsies of polyps and non-changed mucosa of 40 patients, as well as surgical material of 30 patients that underwent surgical treatment of colorectal cancer were carried out. The data were statistically processed using the STATISTICA® for Windows 13.0 package (StatSoft Inc., license № JPZ804I382130ARCN10-J). The median (Me), the lower and upper quartiles (Q1; Q3) were calculated, the comparison between the two groups of observations was performed using the Mann-Whitney test. It was figured out that the polyps are characterized by membranous pattern of EpCAM expression by epitheliocytes with the median equal to 65.22 (33.65; 78.94) CUOD. Comparative analysis of EpCAM expression levels in the polyps and histologically non-changed mucosa, as well as in two studied subgroups of the polyps revealed no significant differences. Colorectal adenocarcinoma is characterized by membranous-cytoplasmic pattern of EpCAM expression by cancer cells with the median equal to 90.86 (80.24; 99.02) CUOD. Comparative analysis of EpCAM expression levels in studied subgroups of the carcinoma (subgroups that correspond to the pTNM stages) revealed the tendency to increasing of EpCAM expression by cancer cells with statistically significant growth of the expression level median during the progression of the tumor from II to IV stages. Furthermore, it was established that the median of EpCAM expression is 28 % higher than the median of the marker expression in the polyps that is statistically significant: 90.86 (80.24; 99.02) CUOD vs. 65.22 (33.65; 78.94) CUOD, р˂0.05. Based on the data obtained, the difference in the patterns of EpCAM expression in the polyps and colorectal carcinoma is due to structural changes that happens to the molecule during colorectal carcinogenesis, moreover, significant increasing of EpCAM expression level at advanced stages of colorectal carcinoma reflects the acquisition of stemness by cancer cells.