Cancer Stem Cells In Colorectal Tumors Of Various Extents.

e15659 Background: The purpose of the study was to assess an association between the tumor invasion and levels of cancer stem cells (CD44+ and CD133+) in colorectal cancer. Methods: The study included colorectal tumor tissues obtained from 60 patients (31 women and 29 men aged 37-78 years). Group 1: 30 patients without distant metastases (T2-4N0M0 n = 21, T3-4N1M0 n = 9), group 2: 30 patients with liver metastases (T3-4aN0M1 n = 8, T3-4аN1-2M1 n = 22). CD44 and CD133 expression on tumor cells was determined by immunohistochemistry. Staining was performed using monoclonal mouse antibodies to CD44 and polyclonal rabbit antibodies to CD133 using the Thermo Scientific autostainer. Membrane staining of ≥10% of tumor cells was evaluated, as well as the staining intensity. Results: We revealed some differences in the expression of the markers. The CD44 expression was found 1.3 times more often in group 1 compared to group 2; significant differences in mean CD44+ values were not found. Comparison of the CD44 expression in the primary tumor and metastases demonstrated lower rates of the positive CD44+ expression in metastatic lymph nodes in group 1 (by 1.7 times) and in liver metastases (by 4.5 times) compared to the primary tumor. The positive CD133+ expression in group 2 exceeded the value in group 1 by 1.4 times; significant differences in mean positive CD133+ values were not found, but the values in group 2 exceeded that in group 1 by 1.6 times. Statistically significant differences in the mean CD133 expression were observed between tumors with minimal (T2-4N0M0) and maximal (T3-4aN1-2M1) invasion, prevailing in the latter (6.3±3.6% vs. 16.7±3.4%, respectively, p≤0.05). An increased CD133 expression was found in liver metastases compared to the primary tumor (by 1.2 times), while in metastatic lymph nodes the level was unchanged. Conclusions: A larger tumor extent in colorectal cancer was associated with decreased CD44 and increased CD133 expression; the latter marker was more often detected in tumors with distant metastases and in metastatic foci.