Fig. 2

Hypoxic-BMSC-derived exosomes promote metastasis of lung cancer cells via EMT. a Cell migration and invasion were measured by transwell assays. A549 cells and LLC cells were treated with hypoxic BMSC-secreted or normoxic BMSC-secreted exosomes for 48 h. Cells that migrated or invaded to the bottom surface were stained with crystal violet and observed by light microscopy (magnification, 100×). b The numbers of migrating cells or invading cells were counted from six fields of view in each group. Data were presented as the mean ± SD, and analyzed with Student’s t-test. *P < 0.05; ** < 0.01; *** < 0.001. c Epithelial and mesenchymal markers in exosome-treated lung cancer cells were measured by quantitative real-time PCR. Experiments were performed in triplicate. *P < 0.05; ** < 0.01. d Bioluminescent images were shown. Timeline of experimental protocol was shown above. C57BL/6 mice were subcutaneously injected with LLC-luciferase cells. When the mean tumor volume reached 100 mm³, the mice were intratumorally injected with exosomes released from hypoxic BMSCs or normoxic BMSCs. Activities of luciferase were shown in histogram. e Representative images of metastatic tumor nodules formed in the lungs