Targeting human colon cancer stem cells (CD133 positive cells) with curcumin and/or 5-FU in high density tumor microenvironment co-culture.

<p>A: High density mono-cultures of HCT116 cells were left untreated (A,Co.HD-mono-culture), high density tumor microenvironment co-culture of HCT116/MRC-5 cells were either left untreated (A,Co.Microenv-HD-Co-culture), or treated with 5-FU (5µM) (A, 5-FU-Microenv-HD-Co-culture), curcumin (5µM) (A, Cur-Microenv-HD-Co-culture) or pre-treated with curcumin (5µM) for 4 h, and then exposed to 5-FU (0.1µM) (A, Cur+5FU-Microenv-HD-Co-culture) for 10 days. Immunolabeling was performed with primary antibodies for colon CSC marker (CD133) followed by incubation with rhodamine-coupled secondary antibodies and counterstaining with DAPI to visualize cell nuclei. Images shown are representative of three different experiments. Magnification 400×. bar 30 nm. B: To quantify the amount of CD133-positive cells in high density cultures described above, 100 cells from 15 microscopic fields were counted. The examination was performed in triplicate, and the results are provided as the mean values with S.D. from three independent experiments. Values were compared with the control and statistically significant values with <i>p<</i>0.05 were designated by an asterisk (*) and <i>p<</i>0.01 were designated by an asterisk (**).