Figure 2. Expression of IL-6 and CXCL8 correlates with lung-colonization efficiency.
CB-17 SCID mice inoculated with 1 × 106 osteosarcoma cells were euthanized 49 days after inoculation. (A) Gross appearance of lung blocks taken from those mice suggests markedly greater efficiency of colonization by OS-17 relative to the other 2 cell lines. Scale bar: 2 mm. (B) H&E stains from sections of paraffin-embedded left lobes were counted to quantify the number of metastases per section. Scale bar: 2 mm. (C) Quantification reveals significantly higher numbers of metastases (mets) in the OS-17 sections relative to both OS-25 and OHS (n = 15 OS-17 and OHS, n = 6 OS-25). (D) Determination of IL-6 and CXCL8 concentrations in 72-hour supernatants from cultures of each cell line reveals significant expression of both cytokines in the metastatic OS-17 cells relative to either nonmetastatic cell line (n = 3 samples per cell line, run in triplicate). (E) Evaluation of capacity to respond to IL-6 and CXCL8 signals using transwell migration assay. Cells were plated in the top chamber and RPMI alone or RPMI containing 50 ng/mL IL-6 or 100 ng/ml IL-8 was placed in the bottom chamber. After 24 hours, plates were harvested and processed as described to quantify the number of cells migrating (n = 3 per condition). **P < 0.01; ***P < 0.001; ****P < 0.0001 relative to OS-17 (C and D) or RPMI (E); 1-way ANOVA with Tukey’s post hoc test.