title: (-)-Epigallocatechin-3-gallate inhibits VEGF expression induced by IL-6 via Stat3 in gastric cancer.
abstract: OBJECTIVE
  To demonstrate that (-)-Epigallocatechin-3-gallate (EGCG) inhibits vascular endothelial growth factor (VEGF) expression and angiogenesis induced by interleukin-6 (IL-6) via suppressing signal transducer and activator of transcription 3 (Stat3) activity in gastric cancer.
  
  
  METHODS
  Human gastric cancer (AGS) cells were treated with IL-6 (50 ng/mL) and EGCG at different concentrations. VEGF, total Stat3 and activated Stat3 protein levels in the cell lyses were examined by Western blotting, VEGF protein level in the conditioned medium was measured by enzyme-linked immunosorbent assay, and the level of VEGF mRNA was evaluated by reverse transcription polymerase chain reaction (RT-PCR). Stat3 nuclear translocation was determined by Western blotting with nuclear extract, and Stat3-DNA binding activity was examined with Chromatin immunoprecipitation (ChIP) assay. IL-6 induced endothelial cell proliferation was measured with 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazoliumbromide assay, in vitro angiogenesis was determined with endothelial cell tube formation assay in Matrigel, and IL-6-induced angiogenesis in vitro was measured with Matrigel plug assay.
  
  
  RESULTS
  There was a basal expression and secretion of VEGF in AGS cells. After stimulation with IL-6, VEGF expression was apparently up-regulated and a 2.4-fold increase was observed. VEGF secretion in the conditioned medium was also increased by 2.8 folds. When treated with EGCG, VEGF expression and secretion were dose-dependently decreased. IL-6 also increased VEGF mRNA expression by 3.1 folds. EGCG treatment suppressed VEGF mRNA expression in a dose-dependent manner. EGCG dose-dependently inhibited Stat3 activation induced by IL-6, but did not change the total Stat3 expression. When treated with EGCG or AG490, VEGF expressions were reduced to the level or an even lower level in the tumor cells not stimulated with IL-6. However, PD98059 and LY294002 did not change VEGF expression induced by IL-6. EGCG inhibited Stat3 nucleus translocation, and Stat3-DNA binding activity was also markedly decreased by EGCG. Furthermore, EGCG inhibited IL-6 induced vascular endothelial cell proliferation and tube formation in vitro and angiogenesis in vitro.
  
  
  CONCLUSIONS
  EGCG inhibits IL-6-induced VEGF expression and angiogenesis via suppressing Stat3 activity in gastric cancer, which has provided a novel mechanistic insight into the anti-angiogenic activity of EGCG.
authors.affiliation: Department of Gastrointestinal and Pancreatic Surgery, First Affiliated Hospital, Sun Yat-Sen University, Gastric Cancer Center of Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, China.
authors.forename: Bao-He
authors.initials: BH
authors.lastname: Zhu
authors.forename: Hua-Yun
authors.initials: HY
authors.lastname: Chen
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Zhan
authors.forename: Cheng-You
authors.initials: CY
authors.lastname: Wang
authors.forename: Shi-Rong
authors.initials: SR
authors.lastname: Cai
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Chang-Hua
authors.initials: CH
authors.lastname: Zhang
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: He
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: D016588:Anticarcinogenic Agents; D015850:Interleukin-6; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D002392:Catechin; C045651:epigallocatechin gallate