title: Synergistic induction of apoptosis by the combination of trail and chemotherapy in chemoresistant ovarian cancer cells.
abstract: OBJECTIVE
  The aim of this study was to investigate whether TNF-related apoptosis-inducing ligand (TRAIL) alone or in combination with chemotherapy could induce apoptosis in ovarian cancer cells resistant to chemotherapy.
  
  
  METHODS
  Twelve chemoresistant epithelial cancer cell lines were treated with each chemotherapeutic drug alone (cisplatin, doxorubicin, or paclitaxel), TRAIL alone, or the combination. Toxicity was assessed using the MTS assay. To assess whether growth inhibition was due to apoptosis, TUNEL assay, caspase activation (measured by caspase-3 and PARP cleavage), and the sub G0/G1 fraction of cells were measured. Synergism was confirmed by fractional inhibition and dose-effect analysis. Expression of death and decoy receptors was studied by immunoblotting and an RNase protection assay. Statistical comparison of means was performed using Student's t test.
  
  
  RESULTS
  The majority of the chemoresistant cells were also resistant to TRAIL alone. In contrast, the combination of TRAIL and chemotherapy resulted in a significant growth inhibition over a wide range of concentrations. This interaction was synergistic by dose-effect analysis. Flow cytometry demonstrated a significant increase in the fraction of apoptotic cells by the combination compared to each reagent alone. A significant enhancement in caspase and PARP cleavage was observed upon treatment with the combination. Finally, no correlation between induction of apoptosis and level of death receptors was found.
  
  
  CONCLUSIONS
  The data suggest that almost all the ovarian cancer cells, which are resistant to chemotherapy, are also resistant to TRAIL. The combination of TRAIL and chemotherapy overcomes this resistance in a synergistic fashion by triggering caspase-mediated apoptosis. The combination of TRAIL and chemotherapy could be useful as a therapy for chemoresistant ovarian cancers.
authors.affiliation: Genetics Department, National Cancer Institute, Bethesda, Maryland 20889, USA.
authors.forename: M
authors.initials: M
authors.lastname: Cuello
authors.forename: S A
authors.initials: SA
authors.lastname: Ettenberg
authors.forename: M M
authors.initials: MM
authors.lastname: Nau
authors.forename: S
authors.initials: S
authors.lastname: Lipkowitz
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology; D004317:Doxorubicin / Q000008:administration & dosage / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D005260:Female; D006801:Humans; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D004317:Doxorubicin; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D017239:Paclitaxel; D002945:Cisplatin