title: [Constitutive activation of signal transducers and activators of transcription 3 and expression of its target gene products in human ESCC cell line].
abstract: OBJECTIVE
  To investigate the expression of signal transducers and activators of transcription 3 (STAT3) and its target gene products including vascular endothelial growth factor (VEGF) and Bcl-2 in two human esophageal squamous cell carcinoma (ESCC) cell lines for understanding whether STAT3 signaling transduction pathway was constitutively activated in ESCC cell lines.
  
  
  METHODS
  Western blotting was used to determine the protein levels of STAT3, p-STAT3 (activated STAT3), VEGF and Bcl-2 in two ESCC cell lines (EC9706 and Eca109). Nuclear proteins from the ESCC cell lines were extracted to evaluate the DNA-binding activity by electrophoretic mobility gel shift assay (EMSA). RT-PCR was used to detect the mRNA of STAT3, VEGF and Bcl-2.
  
  
  RESULTS
  Western blotting and RT-PCR revealed that STAT3, VEGF and Bcl-2 protein and mRNA were overexpressed in the two ESCC cell lines, which contained constitutively activated STAT3 signaling transduction pathway. The results of EMSA of the nuclear protein showed high DNA-binding activity of STAT3.
  
  
  CONCLUSIONS
  STAT3 signaling transduction pathway is constitutively activated in human ESCC cell lines, suggesting that STAT3 may play a critical role in the carcinogenesis of the esophagus.
authors.affiliation: Key Laboratory of Tumor Pathology of Henan Province/Department of Pathology, First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China.
authors.forename: Xin-hua
authors.initials: XH
authors.lastname: Wang
authors.forename: Shan-shan
authors.initials: SS
authors.lastname: Li
authors.forename: Ai-hua
authors.initials: AH
authors.lastname: Yan
authors.forename: Chuang-xin
authors.initials: CX
authors.lastname: Lu
authors.forename: Yan-ping
authors.initials: YP
authors.lastname: Guo
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D004938:Esophageal Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D042461:Vascular Endothelial Growth Factor A