title: Metformin inhibits proliferation and promotes apoptosis of HER2 positive breast cancer cells by downregulating HSP90.
abstract: OBJECTIVE
  To investigate the effects and the possible molecular mechanisms of metformin on HER2 positive breast cancer cells.
  
  
  METHODS
  SK-BR-3 HER2 positive breast cancer cells were treated with different concentrations of metformin. The growth inhibitory rate of the cells was calculated by MTT assay, apoptosis was detected by flow cytometry, and the expression level of heat shock protein 90 (HSP90) was performed by Western blot analysis. A control group consisted of cells treated with PBS.
  
  
  RESULTS
  With increased concentrations of metformin, cell growth inhibitory rates increased. The growth inhibitory rates with 0.5 mM, 2mM or 8mM metformin were significantly higher compared with the control group (p<0.05). Apoptosis in the metformin treated cells was also significantly higher compared with the control group (p=0.003). The expression level of HSP90 in the metformin group was significantly lower than that in the control group.
  
  
  CONCLUSIONS
  Metformin can inhibit the proliferation and promote apoptosis of HER2 positive breast cancer cells,which is maybe related to inhibition of HSP90.
authors.affiliation: Department of Thyroid and Breast Surgery, Affiliated Nanshan Hospital of Guangdong Medical College, Shenzhen, China.
authors.forename: Tian-wen
authors.initials: TW
authors.lastname: Chen
authors.forename: Ya-nan
authors.initials: YN
authors.lastname: Liang
authors.forename: Duo
authors.initials: D
authors.lastname: Feng
authors.forename: Lin-yu
authors.initials: LY
authors.lastname: Tao
authors.forename: Ke
authors.initials: K
authors.lastname: Qi
authors.forename: Hao-yun
authors.initials: HY
authors.lastname: Zhang
authors.forename: Hong-xian
authors.initials: HX
authors.lastname: Wang
authors.forename: Qiu-sheng
authors.initials: QS
authors.lastname: Lin
authors.forename: Heng
authors.initials: H
authors.lastname: Kong
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005260:Female; D005434:Flow Cytometry; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008687:Metformin / Q000494:pharmacology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D018841:HSP90 Heat-Shock Proteins; D008687:Metformin; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human