title: [Effects of metformin on human oral cancer KB cell proliferation and apoptosis in vitro].
abstract: OBJECTIVE
  To investigate the effects of metformin on the proliferation and apoptosis of human oral cancer cell line KB in vitro.
  
  
  METHODS
  Human oral cancer cell line KB was exposed to different doses of metformin (0, 1.25, 2.5, 5, 10, and 20 mmol/L), and the changes in cell viability were detected using MTT assay. Colony formation of the cells was observed following an 8-day metformin exposure. The changes in mitochondrial membrane potential were measured by JC-1 assay, and PI staining was used to observe the cell apoptosis. Western blotting was employed to detect the changes in the protein expressions of GRP78 and activated caspase-3.
  
  
  RESULTS
  Metformin exposure caused time- and dose-dependent suppression of KB cell proliferation, and exposure to 5 mmol/L metformin for 24, 48 and 72 h resulted in cell survival rates of 68.0%, 36.9%, and 14.5%, respectively. Metformin significantly inhibited KB cell colony formation. Exposure of the cells to increased concentrations of metformin gradually increased the apoptotic rate and decreased mitochondrial membrane potential. Metformin caused an initial up-regulation followed by a down-regulation of GRP78 expression in KB cells and increased the expression of activated caspase-3.
  
  
  CONCLUSIONS
  Metformin can inhibit the proliferation and induce apoptosis of KB cells, the mechanism of which may involve the activation of the mitochondrial apoptotic pathway and endoplasmic reticulum stress.
authors.affiliation: First Affiliated Hospital of Bengbu Medical College, Faculty of Pharmacy, Bengbu Medical College, Bengbu 233030, China.E-mail: wf161820@126.com.
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Jincheng
authors.initials: J
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Xia
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.forename: Surong
authors.initials: S
authors.lastname: Zhao
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007624:KB Cells; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008687:Metformin / Q000494:pharmacology*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D008687:Metformin; C505407:CASP3 protein, human; D053148:Caspase 3