title: [Effect of tamoxifen on apoptosis and drug resistance of breast cancer cells in vitro].
abstract: OBJECTIVE
  To study the effect of estradiol (E2) and tamoxifen (TAM) on the apoptosis regulatory genes (bax, bcl-2) and mdr-1 in MCF-7 cells.
  
  
  METHODS
  Immunohistochemistry, in situ hybridization were used to observe the changes in bax, bcl-2 and mdr-1 genes after treatment with E2 and TAM.
  
  
  RESULTS
  E2 had ability to increase the expression of bcl-2 and mdr-1 but TAM decrease the expression of both. Synthetic bax oligodeoxynucleotide (ODN) was used as probe to perform in situ hybridization. It was shown that bax mRNA in MCF-7 cells was down-regulated by E2 and up-regulated by TAM. Significant correlation between bcl-2 and mdr-1 was observed after TAM treatment of MCF-7 cells (P < 0.05).
  
  
  CONCLUSIONS
  TAM regulates cell apoptosis and inhibits development of drug-resistance of MCF-7 breast cancer.
authors.affiliation: Department of General Surgery, Clinical College, Chongqing University of Medical Sciences, Chongqing 400016, China.
authors.forename: J
authors.initials: J
authors.lastname: Zheng
authors.forename: Z
authors.initials: Z
authors.lastname: Yao
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D019450:Genes, MDR; D019254:Genes, bcl-2; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein
chemical_list: D018931:Antineoplastic Agents, Hormonal; C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D013629:Tamoxifen; D004958:Estradiol