Fig. 6

Atorvastatin suppresses breast cancer lung metastatic growth in a mammary mouse model of spontaneous metastasis. The experimental outline for a mammary fat pad (MFP) inoculation model for spontaneous breast cancer metastasis to the lung (a). MDA-MB-231 RFP cells (5 × 10⁵) were innoculated into the right MFP of mice on day 0, mice were treated with six per week intraperitoneal (IP) injections of 2 mg/kg or 10 mg/kg atorvastatin or vehicle (Veh, 2% DMSO in saline) starting on day 10, and mice were euthanized on day 28 for tissue harvesting. Gross pathology was used to examine primary tumor size and the presence or lack of overt lung macrometastases (b). Primary tumor histology was determined by H&E staining (c) and size was determined by tumor cross-sectional area (d). Primary tumor proliferation was assessed by Ki-67 immunohistochemistry (e, f), with Ki-67 represented in brown and counterstained by hematoxolin. Histology of lung metastases was determined by H&E staining (g). Lung metastases proliferation was assessed by Ki-67 immunohistochemistry (h, i), with Ki-67 represented in brown and counterstained by hematoxolin. Significant outliers (n = 1 in the vehicle and 10 mg/kg atorvastatin groups) as detected by Grubbs’ test were removed from the analysis in I. Error bars represent the standard error of the mean. White scalebar = 1 cm, red and black scalebars = 100 µm