Figure 6: CELF1 drives in vivo metastatic colonization.

(a) The effect of CELF1 overexpression on metastatic lung colonization was examined. MCF10AT1 cells stably overexpressing either Renilla Luciferase or CELF1 were injected into the tail vein for experimental metastasis within athymic nude mice. The incidence and progression of metastasis was measured by luciferin injection and bioluminescence imaging of Firefly Luciferase. Mice were killed on day 100 and metastases were quantified in excised lungs by ex vivo bioluminescence imaging. Shown on the right, hematoxylin and eosin staining of the lungs from mice. Scale bar, 1 mm. Black arrows indicate micrometastases. (b) The lungs from each group of experimental animals in a were surgically excised, fixed overnight in 10% buffered formalin and metastatic nodules were counted. Red line denotes 25th percentile. (c) The effect of CELF1 knockdown on metastasis were examined as in a, except that the animals were injected with MFC10CA1a cells stably expressing shRNA hairpins targeting GLB1 or CELF1 (2 distinct shRNAs). Scale bar, 1 mm. (d) The lungs from each group of experimental animals were surgically excised, fixed overnight in 10% buffered formalin and metastatic nodules were counted. Red line denotes 25th percentile. In b and d, *P≤0.05 (Student’s t-test). See also Supplementary Fig. 5.