Xenograft Model of Breast Cancer

Six weeks old female NMRI (Naval Medical Research Institute) nude mice were acquired from Taconic Europe (Lille Skensved, Denmark) and allowed to acclimate one week in the animal facility before any intervention was initiated. All experimental procedures were conducted with the guidelines set forth by the Danish Ministry of Justice. Estrogen pellets, 0.72 mg 17-β-Estradiol, 60-day release (Innovative Research of America, Sarasota, FL, USA), were implanted s.c. during anesthesia with 1:1 v/v mixture of Hypnorm^® (Janssen Pharmaceutica, Beerse, Belgium) and Dormicum^® (Roche, Basel, Switzerland). One week after implantation of pellets, MCF-7 (human breast adenocarcinoma) tumor cells (10⁷ cells in 100 μL medium mixed with 100 μL Matrixgel™ Basement Membrane Matrix (BD Biosciences, San Jose, CA, USA)) were injected subcutaneous into the left and right flank respectively. Cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) medium supplemented with 10% fetal calf serum and 1% penicillin-streptomycin in 5% CO₂ at 37°C.