title: HB-EGF induces delayed STAT3 activation via NF-kappaB mediated IL-6 secretion in vascular smooth muscle cell.
abstract: Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family that binds to and activates EGF receptor, and is expressed in a variety of tissues, predominantly in the lung, heart, brain and skeletal muscle. HB-EGF is known to induce vascular smooth muscle cell (VSMC) proliferation by activating PI3K-Akt and MAPK pathway. However, our preliminary data showed that Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway was also involved in HB-EGF induced VSMC proliferation. More interestingly, HB-EGF (10 ng/ml) induced a biphasic activation of STAT3 (early at 5 min and late at 60-120 min). Therefore, we tried to elucidate the underlying mechanism of this delayed STAT3 activation by HB-EGF in VSMCs. First, we examined the effect of HB-EGF on interleukin-6 (IL-6) mRNA expressions, since IL-6 have been implicated in the regulation of STAT3 activation. According to our data, HB-EGF increased transcription of IL-6, cardiotrophin-1 (CT-1), leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF). The secretion of IL-6 was also increased by HB-EGF. Furthermore, these HB-EGF-mediated up-regulation of IL-6 mRNA expression and secretion were inhibited by NF-kappaB inhibitor Bay117082 (2.5 microM) treatment suggesting involvement of NF-kappaB pathway. Again, the late activation of STAT3 by HB-EGF was abolished by both Bay117082 and IL-6 neutralizing antibody (1 microg/ml) indicating IL-6 is a key molecule in the delayed activation of STAT3 by HB-EGF. In addition, IL-6 neutralizing antibody inhibited both HB-EGF conditioned media induced STAT3 activation and HB-EGF induced VSMC proliferation. In conclusion, IL-6 plays an important role in the delayed activation of STAT3 and VSMC proliferation induced by HB-EGF.
authors.affiliation: Center for Biomedical Sciences, Division of Cardiovascular Diseases, National Institute of Health, Seoul, Korea.
authors.forename: Kuy-Sook
authors.initials: KS
authors.lastname: Lee
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Park
authors.forename: Seahyoung
authors.initials: S
authors.lastname: Lee
authors.forename: Hyun-Joung
authors.initials: HJ
authors.lastname: Lim
authors.forename: Hye-Eun
authors.initials: HE
authors.lastname: Choi
authors.forename: Hyun-Young
authors.initials: HY
authors.lastname: Park
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D053612:Janus Kinases / Q000037:antagonists & inhibitors; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects