Fig. 3
Metastasis-inducing effect of EntF* in an orthotopic mouse model of colorectal cancer. a Schematic timeline of the experimental setup. Female Swiss nu/nu mice were orthotopically injected with 1 × 106 luciferase-transfected HCT-8 cells at the age of 5 weeks. During the following 6 weeks, mice were daily i.p. injected with 102 nmol kg−1 EntF* (n = 38), PBS control (vehicle, n = 17), or 0.1 mg kg−1 EGF positive control (n = 18). Bioluminescent imaging was performed weekly to determine cancer progression. After 6 weeks, mice were euthanized and the cecum, liver and lungs collected. b Graph representing the average daily exposure of placebo-treated (black; n = 65) and EntF*-treated (gray; n = 14) female Swiss nu/nu mice. In the placebo group, mice with an EntF* serum concentration below the limit of detection (100 pM) were counted as zero. The daily exposure after i.p. injection of 102 nmol kg−1 EntF* is 5 times higher than the naturally occurring EntF* levels. c Representative images of bioluminescence activity in vehicle, EntF*-treated, and EGF-treated mice. Mice were i.p. injected with 150 mg kg-1 luciferin and imaged after 10 min in supine position. d Tumor growth curves derived from the quantification of bioluminescence in vehicle, EntF*-treated, and EGF-treated mice. Based on linear regression slope comparison, EntF* and EGF treatment resulted in a significant increase in tumor growth compared to the vehicle. Data represent the mean relative increase in bioluminescence ± SEM. e Representative pictures of vehicle, EntF*-treated, and EGF-treated ceca at the end of the experiment. f Number of tumor nodules in untreated (vehicle), EntF*-treated, and EGF-treated ceca determined by macroscopic inspection of tissues. Data represent the mean nodule number ± SEM. Statistically significant differences were determined by a Mann-Whitney U test with indicated p-values