title: A novel tumor suppressor gene ECRG4 interacts directly with TMPRSS11A (ECRG1) to inhibit cancer cell growth in esophageal carcinoma.
abstract: BACKGROUND
  The esophageal carcinoma related gene 4 (ECRG4) was initially identified and cloned from human normal esophageal epithelium in our laboratory (GenBank accession no.AF325503). ECRG4 has been described as a novel tumor suppressor gene associated with prognosis in esophageal squamous cell carcinoma (ESCC).
  
  
  METHODS
  In this study, binding affinity assay in vitro and co-immunoprecipitation experiment in vivo were utilized to verify the physical interaction between ECRG4 and transmembrane protease, serine 11A (TMPRSS11A, also known as ECRG1, GenBank accession no. AF 071882). Then, p21 protein expression, cell cycle and cell proliferation regulations were examined after ECRG4 and ECRG1 co-transfection in ESCC cells.
  
  
  RESULTS
  We revealed for the first time that ECRG4 interacted directly with ECRG1 to inhibit cancer cell proliferation and induce cell cycle G1 phase block in ESCC. Binding affinity and co-immunoprecipitation assays demonstrated that ECRG4 interacted directly with ECRG1 in ESCC cells. Furthermore, the ECRG4 and ECRG1 co-expression remarkably upregulatd p21 protein level by Western blot (P < 0.001), induced cell cycle G1 phase block by flow cytometric analysis (P < 0.001) and suppressed cell proliferation by MTT and BrdU assay (both P < 0.01) in ESCC cells.
  
  
  CONCLUSIONS
  ECRG4 interacts directly with ECRG1 to upregulate p21 protein expression, induce cell cycle G1 phase block and inhibit cancer cells proliferation in ESCC.
authors.affiliation: Oncology Department, Henan Provincial People's Hospital, Zhengzhou 450003, PR China.
authors.forename: Lin-wei
authors.initials: LW
authors.lastname: Li
authors.forename: Yuan-yuan
authors.initials: YY
authors.lastname: Li
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Li
authors.forename: Chun-peng
authors.initials: CP
authors.lastname: Zhang
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhou
authors.forename: Shih-Hsin
authors.initials: SH
authors.lastname: Lu
mesh_terms: D001667:Binding, Competitive; D015153:Blotting, Western; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D016193:G1 Phase; D016147:Genes, Tumor Suppressor; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C476999:ECRG4 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C446704:TMPRSS11A protein, human; D025521:Tumor Suppressor Proteins; D057057:Serine Proteases