Proliferation characteristics of CD133+ cell population in colorectal cancer.

In this study, CD133+ subpopulations were isolated from 41 primary colorectal cancer tissues, the proliferation and cell cycle distribution of the cells were examined without in vitro expansion, and then compared to those of cell lines. The detection of CD133 in colorectal cancer tissues, isolation of CD133+ and CD133- epithelial subpopulations, Ki-67/DNA multiparameter assay and cell volume analysis were flow cytometrically conducted. The results showed that Ki-67 expression was correlated with CD133 level in primary cancer tissues, while cell cycle G2/M phase distribution or clinicopathological characteristics was not. In addition, the CD133+ cells showed larger cell volume and higher Ki-67 expression as compared with CD133- cells. But there was no statistically significant difference in G(2)/M phase distribution between the two subpopulations. Our results demonstrated that the CD133+ subpopulation in colorectal cancer tissue contained more actively cycling and proliferating cells, which was not correlated to clinicopathological factors but might contribute to tumor progression and poor clinical outcome.