Fig. 6

In vivo evaluation of the combination of regorafenib and 5-FU as a therapeutic combination for drug resistant CRC. a The tumorigenesis of DLD-1R-inoculated mice with different treatment groups was tracked over time. The fold change of tumor volume was recorded over time. The curve demonstrated that the combination suppressed the tumorigenesis the most followed by 5-FU and regorafenib. The insert shows the photographs of tumor samples harvested after the experiment. b Flow cytometry analysis demonstrated that the combination of Regorafenib and 5-FU suppressed the percentage of SP cells most significantly followed regorafenib and 5-FU. c Comparative tumor sphere forming ability. DLD-1R tumor cells harvested from the combination treatment showed the lowest tumor sphere generating ability followed by regorafenib and 5-FU. d Immunohistochemical analysis of tumor sections. Tumor collected from the combination group showed the lowest staining for β-catenin, WNT1 and ABCG2 while the strongest signal of Bax. *p < 0.05, **p < 0.01