title: ATM/ATR and SMAD3 pathways contribute to 3-indole-induced G₁ arrest in cancer cells and xenograft models.
abstract: BACKGROUND
  3-Indole inhibits lung cancer growth by apoptosis. Here, the growth inhibition mechanism besides apoptosis was further characterized.
  
  
  METHODS
  The Comet assay was used to examine 3-indole-induced DNA damage. Cell cycle distribution and protein expression were analyzed using flow cytometry, Western blotting and immunohistochemistry in cell and animal models.
  
  
  RESULTS
  3-Indole induced dose-dependent DNA damage, which was reversed by reactive oxygen species (ROS) inhibitor in lung cancer cells. Cell cycle G₁ arrest was observed in the 3-indole-treated cells. DNA damage-responsive proteins involved in the ataxia telangiectasia mutated/ataxia telangiectasia and Rad3-related (ATM/ATR) pathway and G₁ regulation proteins such as p21 and SMA- and MAD-related protein 3 (SMAD3) were induced in the cell models. The altered expression of ATM, ATR, checkpoint kinase 2 (CHK2), and cell division cycle 25 homolog A (CDC25A) were confirmed in xenograft models. Importantly, the 3-indole-induced ATM/ATR and transforming growth factor (TGF)-β/SMAD pathways were attenuated by ROS inhibitor.
  
  
  CONCLUSIONS
  3-Indole causes DNA damage and triggers ATM/ATR and SMAD3 signaling pathways to arrest lung cancer cells at the G₁-phase.
authors.affiliation: Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan, ROC.
authors.forename: Sin-Ming
authors.initials: SM
authors.lastname: Huang
authors.forename: Kwok-Tung
authors.initials: KT
authors.lastname: Lu
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins / Q000378:metabolism*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D016193:G1 Phase / Q000187:drug effects*; D006801:Humans; D007124:Immunoenzyme Techniques; D007211:Indoles / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051900:Smad3 Protein / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D007211:Indoles; D017382:Reactive Oxygen Species; C497790:SMAD3 protein, human; D051900:Smad3 Protein; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C030374:indole; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases