Novel therapeutic diiminoquinone exhibits anticancer effects on human colorectal cancer cells in two-dimensional and three-dimensional in vitro models

Figure 5 Diiminoquinone reduced the sphere-forming and self-renewal ability of colon cancer stem/progenitor cells. A: HCT116 and B: HT29 cells were seeded at a density of 1000 single cells/well in Matrigel™ for 8 d with and without 1 μmol/L diiminoquinone (DIQ) at generation 1. Spheres were propagated for five generations in duplicates for each condition. Media or treatment was replenished every 2 d. Spheres were counted at day 8-12 of sphere culture. Results are expressed as sphere-formation unit, which was calculated according to the following formula: sphere-formation unit = (number of spheres counted/number of input cells) × 100. Quantification of the average size of generation 1 to generation 5 colon cancer spheres with or without treatment conditions. Spheres sizes were measured by Carl Zeiss Zen 2012 image software. Data represent an average diameter (μm) of 50 measured spheres. Representative bright field images of HCT116 and HT29 colon spheres in Matrigel^TM taken by the Axiovert inverted microscope are shown. Data represent an average of three independent experiments and is reported as mean ± standard error of the mean (^aP < 0.05, ^bP < 0.01, ^cP < 0.001).