2.12 Subcutaneous tumor xenograft models
All protocols involving mice in this study were conducted in accordance with the principles and procedures approved by the Animal Ethics Committee of Northwest A&F University. Animal studies are reported in compliance with the ARRIVE guidelines (Kilkenny, Browne, Cuthill, Emerson, & Altman, 2010; McGrath & Lilley, 2015) and with the recommendations made by the British Journal of Pharmacology . Male BALB/c nude mice (6 to 8 weeks old) were purchased from Sino-British Sippr/BK Laboratory Animal Ltd. (Shanghai, China). The mice were maintained under specific pathogen-free conditions. Five mice were kept in one breeding cage. PANC-1 cells (1 × 106cells suspended in 0.1 mL sterile PBS/animal) were subcutaneously injected into the right flanks of mice with a 1 mL sterile disposable plastic syringe. When the tumors reached an average volume of 100 mm3, the mice were randomly divided into five groups with five mice in each group. The five groups were treated with solvent (PBS with 10% methanol and 10% Tween-80), gemcitabine hydrochloride (80 mg/kg/3d), TA (10 mg/kg/d), TA (20 mg/kg/d), and TA (40 mg/kg/d) by intraperitoneal injection 15 days, respectively. Tumor volume and body weight of the tumor-bearing nude mice were monitored once every three days. The tumor volume was calculated using the following formula: tumor volume (V) = length × width × width × 0.52. At the end of the experiment, the tumor-bearing nude mice were sacrificed by cervical dislocation. The tumors were separated from the surrounding muscles and dermis, weighed, and photographed.