Human colorectal cancer xenograft mouse model

Experiments were performed with outbred male nude mice at 4–6 weeks of age (Charles River Laboratories, Saint-Constant, QC, Canada). The animals were maintained in an animal facility, under specific pathogen-free conditions. Housing and all procedures involving animals were performed according to the protocol approved by the Université de Sherbrooke Animal Care and Use Committee (protocol number 235-14B). Human colorectal HCT116 tumor cells (2 × 10⁶, 0.1 mL) were inoculated subcutaneously (s.c.) into each rear thigh and one on the right shoulder. During each animal handling implantation, the animals were anesthetized with an intraperitoneal injection of ketamine/xylazine (87/13 mg/mL) at 1 mL/kg. Tumor size measurements began 1-week post-injection and continued biweekly. Tumor volumes were calculated with the following formula: V (mm³) = π/6 × a (mm) × b² (mm²), where a and b were the largest and smallest perpendicular tumor diameters, respectively. All experiments began when tumor volumes reached a diameter of about 5–7 mm. The tumor-bearing animals were randomized into different groups of two to four animals each.