title: [Expression of Toll-like receptor 7 in gastric cancer cell lines and effects of TLR7 agonist on proliferation and apoptosis of SGC-7901 cells in vitro].
abstract: OBJECTIVE
  To investigate the expression of Toll-like receptor 7 (TLR7) in gastric cancer cell lines and the effect of imiquimod, a TLR7 agonist, on the proliferation and apoptosis of SGC-7901 cells.
  
  
  METHODS
  The protein expression levels of TLR7 were detected with Western blotting in 3 human gastric cancer cell lines (SGC-7901, HGC-27 and MKN-28). The cell line expressing the highest TLR7 level was exposed to different doses of imiquimod for 12-72 h and the cell viability was assessed with MTT assay. The cell apoptosis rate after 100 µg/ml imiquimod treatment for 12 or 24 h was quantified by flow cytometry, and the ultrastructual changes of the cells were observed under electron microscope. The expression of apoptosis-related genes Bcl-2 and Bax were analyzed with real-time PCR.
  
  
  RESULTS
  All the 3 cell lines expressed TLR7, among which SGC-7901 cells showed the highest expression level. TLR7 agonist imiquimod dose- and time-dependently reduced the viability of SGC-7901 cells. Exposure to 100 µg/ml imiquimod for 24 h resulted in SGC-7901 cell apoptosis as shown by an increased ratio of early apoptotic cells and significant ultrastructural changes of the cells. Real-time PCR demonstrated that imiquimod treatment for 24 h caused a dose-dependent reduction of Bcl-2 mRNA expression and increment of Bax mRNA expression.
  
  
  CONCLUSIONS
  TLR7 protein is expressed in all the 3 gastric cancer lines and its agonist imiquimod can inhibit cell proliferation and induce apoptosis in SGC-7901 cells.
authors.affiliation: Department of Gastroenterology, Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an 710004, China. E-mail: angus712@163.com.
authors.forename: Jiong
authors.initials: J
authors.lastname: Jiang
authors.forename: Lei
authors.initials: L
authors.lastname: Dong
authors.forename: Bin
authors.initials: B
authors.lastname: Qin
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Guo
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Haitao
authors.initials: H
authors.lastname: Shi
authors.forename: Yaping
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology*; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000077271:Imiquimod; D060888:Real-Time Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology; D051199:Toll-Like Receptor 7 / Q000819:agonists* / Q000378:metabolism*
chemical_list: D000634:Aminoquinolines; C495348:TLR7 protein, human; D051199:Toll-Like Receptor 7; D000077271:Imiquimod