title: Bmi-1 is critical for the proliferation and invasiveness of gastric carcinoma cells.
abstract: OBJECTIVE
  Bmi-1 is a transcriptional repressor belonging to the Polycomb group and is associated with the cell proliferation and carcinogenesis of a variety of human cancers. The level of Bmi-1 expression correlates with the aggressiveness of many cancers, and is considered an important marker for cancer diagnosis. However, its role in gastric carcinoma is unknown.
  
  
  METHODS
  We used lentiviral mediated interfering short hairpin RNA to knockdown Bmi-1 expression in gastric carcinoma human gastric cancer cell line (AGS cells), then tested the cell proliferation by MTT assay, rate of colony formation by colony formation assay, cell cycle distribution by fluorescence-activated cell sorting and cell invasiveness by cell invasion assay. To analyze the expression and localization of Bmi-1 in gastric tumor tissues, we further performed the immunohistochemistry analysis on a gastric cancer tissue array.
  
  
  RESULTS
  We found that knocking down Bmi-1 led to slower cell growth, lesser cell invasiveness, decelerated colony formation, and altered cell cycle progression. In addition, a positive relationship between nuclear expression of Bmi-1 and gastric cancer was observed, suggesting that nucleus localization of Bmi-1 in the cells may be a novel marker of gastric cancer.
  
  
  CONCLUSIONS
  Our study highlights critical roles for Bmi-1 in gastric cancer, and suggests that Bmi-1 nuclear localization could be an important marker for the diagnosis of gastric cancer.
authors.affiliation: Cancer Center of the First Hospital of Jilin University, Changchun, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yehui
authors.initials: Y
authors.lastname: Tan
authors.forename: Kewei
authors.initials: K
authors.lastname: Ma
authors.forename: Jiuwei
authors.initials: J
authors.lastname: Cui
mesh_terms: D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D002277:Carcinoma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009361:Neoplasm Invasiveness; D009687:Nuclear Proteins / Q000096:biosynthesis*; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000096:biosynthesis*; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: C069077:BMI1 protein, human; D014408:Biomarkers, Tumor; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1