TNP-470 blockage of VEGF synthesis is dependent on MAPK/COX-2 signaling pathway in PDGF-BB-activated hepatic stellate cells.
Angiogenesis is a key pathogenic event in hepatic fibrogenesis, which is mediated by activated hepatic stellate cells (HSCs). TNP-470 is a known anti-angiogenic agent in cancer, and in this study, we investigated the regulatory mechanisms of TNP-470 blockage of vascular endothelial growth factor (VEGF) synthesis in activated HSCs. Primary HSCs were isolated from rat liver, cultured in vitro, and activated with platelet-derived growth factor-BB (PDGF-BB). After treatment with TNP-470, Nimesulide, PD98059, SB203580 or SP600125, activated HSCs were analyzed by immunoblotting, quantitative RT-PCR, and ELISA for mitogen-activated protein kinase (MAPK) family [ERKs, JNK, and p38], cyclooxygenase-2 (COX-2), and VEGF levels. Phosphorylation of p44/42 MAPK, which was followed by increased expressions of COX-2 and VEGF, was observed in PDGF-BB-activated HSCs; these events could be ameliorated by addition with TNP-470 in time- and dose-dependent manners. TNP-470 also inhibited the secretion of VEGF from activated HSCs into culture supernatant. Furthermore, TNP-470 blockage of VEGF production in activated HSCs could be nullified by exogenous inoculation with prostaglandin E(2). In summary, our findings suggest that TNP-470 exhibits the observed anti-angiogenic properties in activated HSCs by targeting the COX-2/phospho-p44/42 MAPK pathway to inhibit VEGF production.
Wang
Yan Qing
YQ
Center for the Study of Liver Disease, Department of Surgery, The University of Hong Kong, Pokfulam, Hong Kong.
Luk
John M
JM
Chu
Andrew C
AC
Ikeda
Kazuo
K
Man
Kwan
K
Kaneda
Kenji
K
Fan
Sheung Tat
ST
D020533:Angiogenesis Inhibitors / Q000008:administration & dosage; D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D003510:Cyclohexanes; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D000077609:O-(Chloroacetylcarbamoyl)fumagillol; D010982:Platelet-Derived Growth Factor / Q000008:administration & dosage*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012717:Sesquiterpenes / Q000008:administration & dosage*; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
D020533:Angiogenesis Inhibitors; D003510:Cyclohexanes; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012717:Sesquiterpenes; D042461:Vascular Endothelial Growth Factor A; D000077214:Becaplermin; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D020928:Mitogen-Activated Protein Kinases; D000077609:O-(Chloroacetylcarbamoyl)fumagillol