Fig. 5

miR-502-5p targets PD-L1 via CD40/STAT3 pathway. a Bioinformatics predication of interaction between miR-502-5p and CD40 or STAT3. b Luciferase reporter assay showed that miR-502-5p overexpression significantly repressed the luciferase activity of CD40-wt and STAT3-wt, while the luciferase activities of CD40-mut and STAT3-mut were not affected in SGC7901 cells. c The expressions of CD40 and STAT3 determined by qRT-PCR in two gastric cancer cell lines were significantly decreased following miR-502-5p transfection. d, e After transfection with siRNA against CD40 (si-CD40) or siRNA against STAT3 (si-STAT3) for 24 h, total cellular lysates were collected and subjected to the western blot analysis with indicated antibodies. The knockdown efficiency of si-CD40 or si-STAT3 was determined by qRT-PCR. f Chromatin immunoprecipitation (ChIP) assay was performed in SGC7901 cells using the STAT3 antibody. The IgG antibody served as a negative control. Analysis was conducted using specific primers for the promoter region of PD-L1