Fig 2: MiR-146b targets EGFR in ovarian cancer. (A) EGFR is a predicted target of miR-146b. (B) The mRNA expression level of EGFR after miR-146b overexpression. (C) The effects of miR-146b on EGFR protein expression were analysed using Western blotting and quantified. (D) After EGFR knockdown by shRNA, the expression of STAT3 was detected by Western blotting. (E) Western blotting analysis of STAT3 of the miR-146b-overexpressing cells that also overexpressed the EGFR ORF. The data are presented as the mean ± SDs of three independent experiments; ns: not significant; *p < 0.05; **p < 0.01; ***p < 0.001.

Fig 3: MiR-146b inhibits the IL-6-STAT3 pathway in ovarian cancer. (A) Expression of TRAF6 after miR-146b overexpression in ovarian cancer cell lines as determined by qPCR. (B) The mRNA expression level of IL-6 after miR-146b overexpression. (C) The concentration of IL-6 was detected by flow cytometry after miR-146b overexpression. (D) The effects of miR-146b overexpression on total STAT3 protein expression were analysed using Western blotting and quantified. (E) The effects of miR-146b overexpression on STAT3 phosphorylation were analysed using Western blotting and quantified. The data are expressed as the means ± SDs; ns: not significant; *p < 0.05; **p < 0.01; ***p < 0.001.

Fig 4: SDL-1 induced STAT3 protein degradation and decreased STAT3 phosphorylation levels in vitro. MKN1 cells were treated with the specified concentration of SDL-1 for 24 h, and the contents of various proteins in MKN1 cells were detected by Western blot.

Fig 5: Effect of EGFR-IL-6-STAT3 signalling and miR-146b expression on ovarian cancer cell migration. (A) The migration abilities of EOC cells were determined in a Transwell assay. A total of 1 × 105 cells/well were seeded in the upper chamber of the Transwell insert chambers, and cell migration was assessed according to the manufacturer’s protocol. (B) Effects of EGFR on the migration of ovarian cancer cells. (C) Ovarian cancer cells were treated with 10 μM Stattic for 12 h, and cell migration was assessed using Transwell assays and quantified (N = 4 × 104 cells/well).(D) Effects of miR-146b overexpression on the migration and invasion of ovarian cancer cells. The migratory abilities are reflected by the number of cells per microscopic field that had migrated to the underside of the membrane. (E) Effects of miR-146b overexpression and Stattic on the migration of ovarian cancer cells. The data are expressed as the means ± SD; ns: not significant; *p < 0.05; **p < 0.01; ***p < 0.001.