Figure 7.

Activated fibroblasts promote OS metastasis by secreting TGF-βA. The cell invasion ability was detected by transwell assay after TGF-β treatment. B. COL6A1 expression was detected by western blot, confocal microscope and qRT-PCR in OS cells exposed to mock vehicle or TGF-β (0-10 ng/mL) for 12 h. C. COL6A1 protein and mRNA expression in U2OS cells transfected with siRNAs targeting SMAD2 exposed to mock vehicle or TGF-β (5 ng/mL) for 12 h. D. COL6A1-knockdown Saos-2 cells were treated with TGF-β, western blot were performed to detect the expression of COL6A1. E. COL6A1-knockdown Saos-2 cells were treated with TGF-β and transwell assay were performed to detect the migration ability of OS cells. F. The expressions of E-cadherin, N-cadherin, β-catenin and vimentin in OS cells with COL6A1 or si-COL6A1 transfection by western blot, qRT-PCR and confocal microscope (Scale bars: 50 µm). H. COL6A1-knockdown U2OS cells were treated with TGF-β, western blots and qRT-PCR were performed on cell lysates with the indicated antibodies. The protein and mRNA expression of TGF-β was detected in COL6A1 overexpressed OS cells. I. The concentration of TGF-β in OS patients' serum was detected by ELISA (non-Meta: non-metastasis OS patients; Meta: lung metastasis OS patients; H.C.: healthy control). J. Schematic diagram summarizing how COL6A1 promotes OS metastasis via suppressing STAT1 expression and activating CAFs. Exo, exosome. Data represent the mean ± SD of 3 separate determinations. *p < 0.05, **p < 0.01, ***p < 0.001 by Student's t test.