title: Gef gene therapy enhances the therapeutic efficacy of doxorubicin to combat growth of MCF-7 breast cancer cells.
abstract: OBJECTIVE
  The potential use of combined therapy is under intensive study including the association between classical cytotoxic and genes encoding toxic proteins which enhanced the antitumour activity. The main aim of this work was to evaluate whether the gef gene, a suicide gene which has a demonstrated antiproliferative activity in tumour cells, improved the antitumour effect of chemotherapeutic drugs used as first-line treatment in the management of advanced breast cancer.
  
  
  METHODS
  MCF-7 human breast cancer cells were transfected with gef gene using pcDNA3.1-TOPO expression vector. To determine the effect of the combined therapy, MCF-7 transfected and non-transfected cells were exposed to paclitaxel, docetaxel and doxorubicin at different concentrations. The growth-inhibitory effect of gef gene and/or drugs was assessed by MTT assay. Apoptosis modulation was determined by flow cytometric analysis, DNA fragmentation and morphological analysis. Multicellular tumour spheroids (MTS) from MCF-7 cells were used to confirm effectiveness of combined therapy (gef gene and drug).
  
  
  RESULTS
  Our results demonstrate that combined therapy gef gene/drugs (paclitaxel, docetaxel or doxurubicin) caused a decrease in cell viability. However, only the gef-doxorubicin (10 microM) combination induced a greater enhancement in the antitumour activity in MCF-7 cells. Most importantly, this combined strategy resulted in a significant synergistic effect, thus allowing lower doses of the drug to be used to achieve the same therapeutic effect. These results were confirmed using MTS in which volume decrease with combined therapy was greater than obtained using the gene therapy or chemotherapy alone, or the sum of both therapies.
  
  
  CONCLUSIONS
  The cytotoxic effect of gef gene in breast cancer cells enhances the chemotherapeutic effect of doxorubicin. This therapeutic approach has the potential to overcome some of the major limitations of conventional chemotherapy, and may therefore constitute a promising strategy for future applications in breast cancer therapy.
authors.affiliation: Department of Human Anatomy and Embryology, School of Medicine, Institute of Biopathology and Regenerative Medicine, University of Granada, 18071, Granada, Spain. jcprados@ugr.es
authors.forename: Jose
authors.initials: J
authors.lastname: Prados
authors.forename: Consolación
authors.initials: C
authors.lastname: Melguizo
authors.forename: Ana Rosa
authors.initials: AR
authors.lastname: Rama
authors.forename: Rául
authors.initials: R
authors.lastname: Ortiz
authors.forename: Ana
authors.initials: A
authors.lastname: Segura
authors.forename: Houria
authors.initials: H
authors.lastname: Boulaiz
authors.forename: Celia
authors.initials: C
authors.lastname: Vélez
authors.forename: Octavio
authors.initials: O
authors.lastname: Caba
authors.forename: Juan Luís
authors.initials: JL
authors.lastname: Ramos
authors.forename: Antonia
authors.initials: A
authors.lastname: Aránega
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000628:therapy*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003131:Combined Modality Therapy / Q000379:methods*; D000077143:Docetaxel; D004317:Doxorubicin / Q000008:administration & dosage* / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D017239:Paclitaxel / Q000008:administration & dosage* / Q000494:pharmacology; D018874:Spheroids, Cellular / Q000187:drug effects; D043823:Taxoids / Q000008:administration & dosage / Q000494:pharmacology; D014162:Transfection / Q000379:methods
chemical_list: D000970:Antineoplastic Agents; D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D043823:Taxoids; C071524:HokC protein, E coli; D000077143:Docetaxel; D004317:Doxorubicin; D017239:Paclitaxel