title: [Up-regulation of c-myc expression in MCF-7/Adr human breast cancer cells and its association with resistance against doxorubicin].
abstract: OBJECTIVE
  To investigate the expression of c-myc in drug-resistant MCF-7/Adr human breast cancer cells and the counteractive effect of c-myc antisense oligonucleotide on their drug-resistance.
  
  
  METHODS
  Flow cytometry was performed to examine c-myc expression in multi-drug resistant MCF-7/Adr cell line and its parental cell line MCF-7. The IC50 value of doxorubicin was evaluated by MTT assay.
  
  
  RESULTS
  MCF-7/Adr cell line was shown to have a significantly higher expression rate of c-myc than its parent cell line MCF-7 (70.48% vs 46.02%). The IC50 value of doxorubicin was (22.00+/-1.92) micomol/L in MCF-7/Adr cells, which was significantly decreased to (9.60+/-1.04) micromol/L (P<0.05) after coincubation with 4 micromol/L c-myc antisense oligonecleotide.
  
  
  CONCLUSIONS
  c-myc expression is up-regulated in MCF-7/Adr cells as compared with their parent cell line MCF-7. Inhibition of c-myc expression may partially reverse the resistance of MCF-7/Adr against doxorubicin, suggesting that c-myc may be involved in the mechanism of drug-resistance of tumor cells.
authors.affiliation: Departments of Radiotherapy,Zhujiang Hospital, First Military Medical University, Guangzhou 510282, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Yuan
authors.forename: Ji-Ren
authors.initials: JR
authors.lastname: Zhang
authors.forename: Dian-Yuan
authors.initials: DY
authors.lastname: Zhou
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005260:Female; D006801:Humans; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D016271:Proto-Oncogene Proteins c-myc; D004317:Doxorubicin