2.8. In vivo xenograft mouse models

MCF-7 and MDA-MB-231 cells (5 × 10⁶ cells/mouse) were ectopically inoculated in the interscapular region of 5/6-week-old athymic nude female mice (n = 5), under anesthesia induced by intraperitoneal injection of 250 mg/kg Avertin. In order to promote the growth of the estrogen-dependent MCF-7 cell line, an extended-release pellet of 17β-estradiol (0.72 mg per pellet, 90-day release; Innovative Research of America) was previously implanted in the dorso-lateral region of each mouse. Tumor development was monitored using a caliper, and tumor volume was calculated using formula V = L(W)²/2 (where L is length and W is width). When tumors reached a volume of approximately 0.2 cm³, mice were randomized and divided into groups, based on treatment. Mice were treated 3 times/week, by intraperitoneal administration of thioalbamide (0.5 mg/kg) or 0.9% NaCl (control groups) and tumor size was constantly monitored during the experiment. As previously described [18], at the end of the treatment period, animals were euthanized and tumor masses were isolated from the surrounding tissues, weighed, fixed in formalin and embedded in paraffin for subsequent histological analysis.