title: Inhibition of epithelial-mesenchymal transition in A549 cell by transfected Napsin A.
abstract: BACKGROUND
  Epithelial-mesenchymal transition is a cellular process characterized by the loss of cell adhesion, inhibition of E-cadherin expression, and increased cell mobility. Cells without Napsin A are susceptible to transition. Further studies are required to investigate whether this transition can be reversed by restoration of Napsin A.
  
  
  METHODS
  A Napsin A expression vector PLJM1-Napsin A plasmid was constructed and then transfected into the epithelial cell line A549 by lentivirus transfection to obtain A549-PLJM1-Napsin A cell line. Cell proliferation was assayed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide and cell cycle was measured by flow cytometry. The E-cadherin, type I collagen, and focal adhesion kinase mRNA level was detected by reverse transcription-polymerase chain reaction. The Napsin A, E-cadherin, type I collagen, and focal adhesion kinase protein level in A549 cells was detected by Western blotting.
  
  
  RESULTS
  Transforming growth factor-b1 induced epithelial-mesenchymal transition in A549 cells, as demonstrated by significant reduction of E-cadherin mRNA and protein levels (P < 0.01) as well as up-regulation of type I collagen (P < 0.01). Transfection of Napsin A in A549 cells can partially block the transforming growth factor-b1-regulated expression of E-cadherin and type I collagen (P < 0.01). In addition, transforming growth factor-b1-induced cell proliferation was inhibited by Napsin A (P < 0.01). Further study demonstrated that Napsin A caused G(0)/G(1) arrest and inhibited the expression of focal adhesion kinase (P < 0.01), a key protein in the integrin signaling pathway, in the in vitro epithelial-mesenchymal transition model.
  
  
  CONCLUSIONS
  Sustained Napsin A expression in A549 cells can inhibit the transforming growth factor-b1-induced epithelial-mesenchymal transition. This may be due to the Napsin A-mediated inhibition of focal adhesion kinase expression and integrin signaling pathway.
authors.affiliation: Department of Respiratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, China. jxuzh135@163.com
authors.forename: Jin-Xu
authors.initials: JX
authors.lastname: Zheng
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Guan
authors.forename: Qing
authors.initials: Q
authors.lastname: Xu
authors.forename: Ji-Zhu
authors.initials: JZ
authors.lastname: Liu
authors.forename: Ping
authors.initials: P
authors.lastname: Song
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: D015820:Cadherins; D024042:Collagen Type I; D053773:Transforming Growth Factor beta1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D016282:Aspartic Acid Endopeptidases; C498549:NAPSA protein, human