Basic fibroblast growth factor upregulates adrenomedullin expression in ovarian epithelial carcinoma cells via JNK-AP-1 pathway

Adrenomedullin (AM), a potent vasodilator peptide, present in various kinds of tumors. Basic fibroblast growth factor (bFGF) has broad biological functions involving in the regulation of cell growth, differentiation and proliferation. Here we investigated whether AM expression could be induced by bFGF in human ovarian epithelial carcinoma cells and explored the mediating mechanism. The expression of AM was examined by real time PCR and Western blotting. Transcriptional control was analyzed by transient transfection assay, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay. AM expression was detected in ovarian epithelial carcinoma both in mRNA and protein levels in vivo. AM mRNA expression in CAOV3 was induced by bFGF in a time- and dose-dependent manner, which could be attenuated by bFGF neutralizing antibody. JNK was activated by bFGF stimulation. The bFGF induced increase in AM expression was significantly attenuated by SP600125, a specific JNK inhibitor. EMSA study, ChIP assay and promoter activity analysis showed that AM expression induced by bFGF requires the AP-1 motif on the AM promoter, which is located at − 1174 and − 922 bp upstream of the transcription start site. The present study demonstrated that AM is expressed in ovarian epithelial carcinoma tissue and bFGF can induce the expression of AM through the JNK-AP-1 pathway in ovarian epithelial carcinoma cell line CAOV3.