Fig. 6. The profibrotic factor SOX9, induced by FGF2 elevation, is required for G-MDSC-mediated suppression of senescence and apoptosis.

A GSEA showing the SOX9-related gene set enriched in the fibroblasts treated with FGF2. B Luciferase activity driven by the SOX9 motif in the fibroblasts treated with FGF2. An asterisk indicates a significant difference vs. the pShuttle promoter; n = 5 per group. C–G The fibroblasts with SOX9 knockdown in vitro were cultured with medium supplemented with FGF2 (4 ng/mL) for 24 h. C Western blotting analysis showing the expression level of SOX9 in senescent fibroblasts. D Representative X-gal staining images (top) and statistical data (bottom) on fibroblast senescence; n = 6 per group. Scale bars, 50 μm. E The mRNA levels of the senescence markers Cdkn2a and Cdkn2b in senescent fibroblasts; n = 8 per group. F Cell cycle distribution and the percentage of fibroblasts in S phase were detected by flow cytometry through PI staining; n = 6 per group. G Representative flow cytometric images and statistical data of apoptosis rates of senescent fibroblasts determined by Annexin V-FITC and PI staining; n = 8 per group. The data are presented as the means ± SDs. Differences were determined by one-way ANOVA (more than 2 groups), and Tukey’s HSD post hoc test was performed. *P < 0.05.