Role of epithelial-mesenchymal transition in the enrichment of colorectal cancer stem cells

Abstract

Objective 　To explore whether the enrichment of cancer stem cells (CSCs) in colorectal cancer by suspension culture method is involved with epithelial-mesenchymal transition (EMT). Methods 　3D microspheres were cultured by suspension culture method to human colorectal cancer SW620 cells. The 3D microspheres and SW620 cells were used as the research objects. To clarify whether 3D microspheres were enriched with CSCs, we made tumorigenicity experiments in NOD/SCID mice, soft agar cloning experiments, and detected the expression levels of cancer stem cells markers CD44 and Ep-CAM by flow cytometry or by Western blotting. The protein expression levels of EMT markers such as E-cadherin, N-cadherin and vimentin were detected by Western blotting. Results 　Compared with the parental SW620 cells, colony formation in vitro (P<0.01) and tumorigenicity in NOD/SCID mice were significantly enhanced, the percentage of CD44-positive cells and Ep-CAM protein expression levels was significantly increased (P<0.01) in 3D microspheres. The protein expression level of epithelial marker E-cadherin was obviously increased (P<0.01), while the protein expression levels of mesenchymal markers N-cadherin and vimentin were significantly decreased (P<0.01). Conclusions 　Colorectal cancer stem cells can be enriched by suspension culture method, and the process may be related to EMT. DOI: 10.11855/j.issn.0577-7402.2016.09.03