title: Synergistic anticancer potential of dichloroacetate and estradiol analogue exerting their effect via ROS-JNK-Bcl-2-mediated signalling pathways.
abstract: BACKGROUND
  C9, a newly in silico-designed inhibitor of microtubule dynamics induces G2/M arrest culminating in apoptosis. Dichloroacetate (DCA) inhibits pyruvate dehydrogenase kinase, an enzyme that promotes pyruvate entry into mitochondria. The use of antitumor drugs targeting different cancer features can be a more effective way to overcome drug resistance.
  
  
  METHODS
  The influence of C9 (130 nM) + DCA (7.5 mM) on MCF-7 and MCF-12 cells was assessed via microscopy spectrophotometry global gene expression and flow cytometry assays.
  
  
  RESULTS
  An LDH assay showed that C9+DCA treatment decreased cell viability to 83.5% in MCF-7 cells when compared to the non-tumorigenic MCF-12A cells 92.4% (P < 0.05). C9- and C9+DCA treatment induced mitochondrial membrane potential depolarization in MCF-7 cells but not in MCF-12A cells (P < 0.05). The occurrence of apoptosis was associated with increased hypo- and hyper-phosphorylation of Bcl-2 Ser(70) and caspase 7 activation. Kinase inhibition revealed sustained activation of the JNK pathway caused increased Bcl-2 protein Ser(70) hypo-and hyper-phosphorylation. Elevated levels of DCF fluorescence was observed in DCA-, C9- and C9+DCA-exposed MCF-7 cells, but not in MCF-12A cells, indicating cytosolic H₂O₂/Fe(2+) formation in treated tumorigenic cells. LC3-II expression was elevated in C9+DCA-treated cells in both cell lines, indicating that autophagy was also induced.
  
  
  CONCLUSIONS
  Synergistic effects of C9+DCA were demonstrated on breast carcinoma and non-tumorigenic cells with selectivity towards the MCF-7 cells. Antimitotic compound C9 in combination with a glycolytic inhibitor dichloroacetate eradicates breast cancer cells through ROS-JNK-Bcl-2-mediated signalling pathways in vitro and it is argued that autophagy acts as protective mechanism in the treated cells before apoptosis occurs.
authors: Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, Gauteng, South Africa.
authors: Xiao Xing
authors: XX
authors: Stander
authors: Barend André
authors: BA
authors: Stander
authors: Annie Margaretha
authors: AM
authors: Joubert
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D053179:Caspase 7 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003999:Dichloroacetic Acid / Q000737:chemistry / Q000494:pharmacology*; D004357:Drug Synergism; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D061986:MCF-7 Cells; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D004958:Estradiol; D003999:Dichloroacetic Acid; D048031:JNK Mitogen-Activated Protein Kinases; D053179:Caspase 7