title: Gossypol, a phytochemical with BH3-mimetic property, sensitizes cultured thoracic cancer cells to Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand.
abstract: OBJECTIVE
  Chemotherapeutic agents sensitize cancer cells to Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) via recruitment of the mitochondria-dependent activation of caspase and induction of apoptosis. This study was designed to evaluate whether gossypol, a phytochemical compound with BH3-mimetic property that functions as an inhibitor of Bcl2/BclXL, would sensitize cultured thoracic cancer cells to this death-inducing ligand.
  
  
  METHODS
  Cancer cell lines from the lung (H460, H322), the esophagus (TE2, TE12), and the pleura (H290, H211) or primary normal cells were treated with gossypol+Apo2L/TRAIL combinations. Cell viability and apoptosis were evaluated by (4,5-dimethylthiazo-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) assays, respectively. Caspase 9 and 3 specific proteolytic activity in combination-treated cells was determined by fluorometric enzymatic assay.
  
  
  RESULTS
  Gossypol, selectively cytotoxic to cancer cells and not primary normal cells, significantly sensitized thoracic cancer cells to Apo2L/TRAIL as indicated by 1.5- to more than 10-fold reduction of Apo2L/TRAIL 50% inhibitory concentration values in cells treated with gossypol+Apo2L/TRAIL combinations. Whereas less than 20% of cancer cells exposed to either gossypol (5 micromol/L) or Apo2L/TRAIL (20 ng/mL) were dead, more than 90% of cells treated with the drug combinations were apoptotic. Combination-induced cytotoxicity and apoptosis was completely abrogated either by overexpression of Bcl2 or by the selective caspase 9 inhibitor. This combination was not toxic to normal cells.
  
  
  CONCLUSIONS
  Gossypol profoundly sensitizes thoracic cancer cells to the cytotoxic effect of Apo2L/TRAIL via activation of the mitochondria-dependent death signaling pathway. This study provides evidence for the profound anticancer activity of this drug combination and should be further evaluated as a novel targeted molecular therapeutic for thoracic cancers.
authors.affiliation: Section of Thoracic Oncology, Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Md, USA.
authors.forename: Wen-Shuz
authors.initials: WS
authors.lastname: Yeow
authors.forename: Aris
authors.initials: A
authors.lastname: Baras
authors.forename: Alex
authors.initials: A
authors.lastname: Chua
authors.forename: Duc M
authors.initials: DM
authors.lastname: Nguyen
authors.forename: Shailen S
authors.initials: SS
authors.lastname: Sehgal
authors.forename: David S
authors.initials: DS
authors.lastname: Schrump
authors.forename: Dao M
authors.initials: DM
authors.lastname: Nguyen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects; D004938:Esophageal Neoplasms / Q000473:pathology*; D006072:Gossypol / Q000494:pharmacology*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008654:Mesothelioma / Q000473:pathology*; D010997:Pleural Neoplasms / Q000473:pathology*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000187:drug effects* / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D053221:TNF-Related Apoptosis-Inducing Ligand; D006072:Gossypol