541 0007-4888/19/16740541--©-2019--Springer-Science+Business-Media,-LLC Proliferative Activity of Colorectal Cancer Cells with Different Levels of CD133 Expression A. M. Gisina 1 , Ya. S. Kim 1 , D. M. Potashnikova 2 , A. V. Tvorogova 2 , K. N. Yarygin 1 , and A. Yu. Lupatov 1 Translated from Kletochnye Tekhnologii v Biologii i Meditsine, No. 2, pp. 84-89, June, 2019 Original article submitted November 30, 2018 We studied proliferative activity of colorectal cancer cells with different expression level of CD133 molecule associated with cancer stem cells phenotype. Analysis of BrdU incorporation into Caco-2 and HT-29 cell lines showed that the percentage of cells in the DNA synthesis phase in the CD133 +/high population is higher than in CD133 —/low population. The expression of proliferation marker Ki-67 and the percentage of Ki-67 + cells were also higher in the CD133 +/high population. Colorimetric analysis with crystal violet dye showed that the number of cells after 10-days culturing was higher in the CD133 +/high population in both cell lines. These findings suggest that cells with high level of CD133 expression are characterized by higher proliferative activity, which can contribute to the tumor progression. Key Words: CD133; cell proliferation; Caco-2; HT-29 1 V. N. Orekhovich Research Institute of Biomedical Chemistry; 2 M. V. Lo- monosov Moscow State University, Moscow, Russia. Address for cor- respondence: alisa.gisina@gmail.com. A. M. Gisina Surface marker CD133 (prominin-1) is often used for detection of cancer cells of many solid tumors [1,7]. Enhanced expression of this factor correlates with un- favorable prognosis of the cancer disease [7]. Howev- er, the function of this molecule remains little studied. It is known that CD133 is predominantly located on plasma membrane processes and microvilli, which in- dicates possible involvement of this molecule in mem- brane structure organization [4]. CD133 is directly associated with cholesterol-containing lipid rafts and therefore can be involved in various signal pathways [9]. CD133 gene knockout determines a defect in the formation of the outer segment of photoreceptor cells, which leads to retina degeneration and blindness [10]. It was found that expression of CD133 is stimulated by hypoxia in stem cells and in the tumor environment [5]. There are data that CD133 is associated with Wnt/ β-catenin signaling pathway. In particular, deacetylase HDAC5 physically interacts with CD133 in mamma- lian cells. This interaction stabilizes β-catenin, while inhibition of CD133 or HDAC5 leads to enhanced acetylation and degradation of β-catenin, which cor- relates with inhibition of cell proliferation in vitro and suppression of the growth of tumor xenotrans- plant [8]. It was demonstrated that CD133 through interaction with Src-kinase followed by activation of FAK signaling is involved into stabilization of EGFR, inhibition of apoptosis, and stimulation of cell migra- tion and metastasizing [6]. However, available data do not fully describe the role of CD133 + cells in tumor populations. In the present study we analyzed the relationships between CD133 expression and proliferative activity of colorectal adenocarcinoma cells. MATERIALS AND METHODS The study was performed on Caco-2 and HT-29 colorectal adenocarcinoma cells. The cells were grown in DMEM/F-12 medium (PanEco) containing 10% fe- tal calf serum (Gibco) at 37 o C and 5% СО 2 . Cultured cells were harvested by incubation with 25% trypsin and Versene (1:1; PanEco) and washed with Hanks saline (PanEco). CD133 expression was measured by flow cytometry. To this end, the cells were stained with primary labeled monoclonal antibodies to hu- Cell Technologies in Biology and Medicine,  No.  2,  August, 2019 DOI 10.1007/s10517-019-04569-y