Mesenchymal Stem Cells Trigger Epithelial to Mesenchymal Transition in the HT-29 Colorectal Cancer Cell Line

 Mesenchymal stem cells (MSCs) promote metastasis in colorectal cancer; however, the mechanism underlying this process is not fully understood. Epithelial to mesenchymal transition (EMT) is a key step in tumor acquisition of metastatic phenotype. We aimed to investigate the effect of MSCs on the expression of EMT markers, as well as cancer stem cell markers in HT-29 colorectal cancer cells.

 MSCs were isolated from bone marrow tissue, and their multi potency was confirmed. The HT-29 cell line was prepared and co-cultured with MSCs for 3 days using 6-well transwell co-culture plates (membrane pore size: 0.4 µm). Cell morphology was observed by inverted microscopy. The expression levels of EMT-related genes, namely E-cadherin, Vimentin, and β-catenin, were investigated by the RT-qPCR method. Also, the surface expression levels of CD44 and CD133 cancer stem cell markers were analyzed by flow cytometry.

 The co-culture of HT-29 cells with bone marrow-derived MSCs resulted in changes in cell morphology from epithelial to mesenchymal forms. The expression of mesenchymal stem cell markers, namely Vimentin and β-catenin, were significantly increased (2.25 and 1.83 folds, respectively), while the expression of the epithelial marker, E-cadherin, was reduced (0.3 folds). The expression of CD133 was also increased (51.5%).

 Tumor-resident mesenchymal stem cells can promote colorectal cancer metastasis inducing EMT as well as increasing cancer stem cell frequency in the tumor microenvironment. It seems that direct contact between MSCs and colorectal cancer cells is not required for the interaction. Our findings may help scientists to find effective strategies against cancer metastasis by targeting tumor-resident MSCs.