title: Calycosin stimulates proliferation of estrogen receptor-positive human breast cancer cells through downregulation of Bax gene expression and upregulation of Bcl-2 gene expression at low concentrations.
abstract: BACKGROUND
  Calycosin is one of main components in the herb radix astragali and is considered a typical phytoestrogen. It has either estrogenic or antiestrogenic effects that mainly depend on estrogen levels in vivo. This study investigated the effects and mechanisms of calycosin on estrogen receptor (ER)-positive human breast cancer (MCF-7) cells in vitro.
  
  
  METHODS
  ER-positive MCF-7 cells were treated with different concentrations of calycosin. Effects of calycosin on the proliferation of ER-positive MCF-7 cells were determined by the MTT assay. Apoptosis in these treated cells was examined by flow cytometry. The mRNA and protein levels of Bcl-2 and Bax in these treated cells were also determined by reverse-transcription polymerase chain reaction and immunohistochemical staining, respectively.
  
  
  RESULTS
  Compared with the vehicle control, calycosin stimulated proliferation of ER-positive MCF-7 cells at low concentrations (2, 4, and 8 µmol/L). Furthermore, at these concentrations, calycosin decreased the percentage of early apoptosis in MCF-7 cells, downregulated mRNA and protein levels of Bax, and upregulated those of Bcl-2 at low concentrations. On the other hand, calycosin at higher concentrations (16 and 32 µmol/L) inhibited cell proliferation.
  
  
  CONCLUSIONS
  At relatively low concentrations, calycosin has stimulatory effects on the proliferation of MCF-7 cells, with the estrogenic effect the mechanism.
authors.affiliation: Department of Pharmacology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Wen-bi
authors.initials: WB
authors.lastname: Xiong
authors.forename: Yao
authors.initials: Y
authors.lastname: Xiong
authors.forename: Yi-ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Xia-jing
authors.initials: XJ
authors.lastname: Chen
authors.forename: Zheng-jun
authors.initials: ZJ
authors.lastname: Shao
authors.forename: Li-tao
authors.initials: LT
authors.lastname: Liu
authors.forename: Wen-juan
authors.initials: WJ
authors.lastname: Kuang
authors.forename: Xian-shu
authors.initials: XS
authors.lastname: Tan
authors.forename: Li-ming
authors.initials: LM
authors.lastname: Zhou
mesh_terms: D027883:Astragalus Plant / Q000009:adverse effects / Q000737:chemistry*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D019254:Genes, bcl-2; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000009:adverse effects*; D048789:Phytoestrogens / Q000009:adverse effects*; D010936:Plant Extracts / Q000009:adverse effects*; D018517:Plant Roots; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D007529:Isoflavones; D048789:Phytoestrogens; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; D011960:Receptors, Estrogen; D051028:bcl-2-Associated X Protein; C121707:7,3'-dihydroxy-4'-methoxyisoflavone