Inhibition of FLNa promotes cancer progression to metastases in a preclinical orthotopic breast cancer model. MDA-231-ErbB2 cells expressing empty retroviral particles (PSR) or particles containing control scrambled shRNA (PSR-scramble) or FLNa-specific shRNA (PSR-FLNa) were implanted into the mammary fat pad of 10 SCID mice per cell type. Primary tumors were excised when they reached a size of 0.6–0.8 cm3, and animals were kept under observation for a period of 3 mo to allow metastasis formation. Mice were then subjected to autopsy, and lung metastases were examined. (A) Representative Western blot analysis of total cell extracts from MDA-231-ErbB2 tumor cells isolated from lung metastatic nodules confirming efficient stability of FLNa knockdown after in vivo implantation. GAPDH was used as an internal control. MM, molecular mass. (B) Graphs show the mean number of lung metastases ± SEM (*, P < 0.005), and images show representative lungs with metastatic nodules. Arrows indicate surface lung metastatic nodules. Bar, 8 mm.
