Figure 7
OSM promotes lung metastasis of breast cancer xenografts. (a) In all, 2.5 × 106 MCF-7/GFP cells were inoculated into the right inguinal fat pad of each BALB/c female nude mice (4–5 weeks old). When the xenografts were palpable, 20 ng OSM (n=8) or phosphate-buffered saline (PBS; n=6) was injected into the tumors once a week for consecutive 6 weeks. The mice were killed after 60 days. Fluorescent images of the mice were acquired by a NightOwl LB 981 Molecular Light Imager (Berthold Technologies, Bad wildbad, Germany). (b) The tumors were dissected and weighed. (c) The tumor and lung tissues were formalin-fixed. The paraffin-embedded sections were subjected to hematoxylin and eosin staining or probed with the anti-GFP antibody. (d) The tumor tissue samples were lyzed and the expression levels of MMP-2, MMP-7, MMP-9, COX-2, CXCR4, E-cadherin, vimentin, ZEB1, Stat3 and p-Stat3 were analyzed by western blot. (e, f) The expression levels of let-7e and miR-200c in the tumor tissues injected with PBS or OSM were evaluated by real-time RT–PCR. (g) Diagram of the mechanism of Stat3-coordinated Lin-28–let-7–HMGA2 and miR-200–ZEB1 circuits initiate and maintain OSM-driven EMT.
