EGFR/STAT3 signaling mediates the upregulation of CD47 in HPV-positive cervical cancer by activating p65 and exosome transporter RAB31
In cervical cancer, the regulatory mechanisms of CD47 and its enrichment in exosomes have not been fully elucidated. In this study, we aim to explore the mechanisms of how EGFR/STAT3 signaling regulates CD47 expression in cervical cancer, and whether p65 or RAB31 is involved in this process. RNA interference was used to knock down the fragment of HPV in cervical cancer cells. EGFR and RAB31 phosphorylation were detected by western blot, and exosomal CD47 was determined by ELISA. EGFR or STAT3 was then knocked down and western blot was used to detect the expression or phosphorylation of EGFR, STAT3, p65, CD47, RAB31, and its related proteins. ChIP-qPCR was used to investigate p65 enrichment in the CD47 promoter region. Our results showed that HPV fragment knockdown reduced the phosphorylation of EGFR and RAB31, and exosomal CD47 expression. Knocking down EGFR inhibited phosphorylation of STAT3 and p65, and expression of RAB31-related proteins. Phosphorylated p65 was bound to the P3 and P7 promoter regions of CD47. EGFR/STAT3 signaling upregulated CD47 expression by phosphorylating p65 and enhanced exosomal CD47 by activated RAB31. Thus, a dual regulatory role of EGFR/STAT3 signaling on CD47 expression and secretion involving transcriptional factor p65 and exosome transporter RAB31 was demonstrated.