title: Targeting 3-phosphoinositide-dependent protein kinase 1 by N-acetyl-cysteine through activation of peroxisome proliferators activated receptor alpha in human lung cancer cells, the role of p53 and p65.
abstract: BACKGROUND
  N-Acetyl-Cysteine (NAC), a natural sulfur-containing amino acid derivative, and peroxisome proliferators activated receptor alpha (PPARα) ligand have been shown to have anticancer properties. However, the mechanisms by which these agents inhibit human non-small cell lung carcinoma (NSCLC) cell growth have not been well elucidated.
  
  
  METHODS
  Small interfering RNAs (siRNAs) were used to knockdown 3-phosphoinositide-dependent protein kinase 1 (PDK1), PPARα, p65 and p53 genes; Western Blot was performed to detect the protein expression of PDK1, PPARα, p65 and p53; Cell viability and MTT assays were carried out to determine the cell proliferation; Transient transfection and Dual-Luciferase Reporter assays were used to transfect siRNAs or exogenous expression vectors, and to measure the gene promoter activity.
  
  
  RESULTS
  We showed that NAC inhibited NSCLC cell proliferation through reduction of PDK1 expression. NAC also induced the protein expression of PPARα. While PPARα ligand enhanced, PPARα antagonist and siRNA abrogated the effect of NAC on PDK1 promoter activity, protein expression and cell growth. Overexpression of PDK1 diminished the inhibitory effect of NAC on cell proliferation. NAC induced p53 and reduced p65 protein expression through activation of PPARα. Silencing of p53 and overexpression of p65 blocked the effect of NAC on PDK1 promoter activity and protein expression.
  
  
  CONCLUSIONS
  Our results show that NAC inhibits PDK1 expression through PPARα-mediated induction of p53 and inhibition of p65 protein expression. PPARα ligand enhances the effect of NAC. This ultimately inhibits NSCLC cell growth. This study unveils a novel mechanism by which NAC in combination with PPARα ligand inhibits growth of human lung carcinoma cells.
authors.affiliation: Second Clinical Medical Collage, University of Guangzhou Traditional Chinese Medicine, Guangdong Academy of Traditional Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Room 421, 4th Floor, Scientific Research Building, Neihuan West Road No, 55, University City, Panyu District, Guangzhou, Guangdong Province 510120, PR China. swhan2010@live.com
authors.forename: Swei Sunny
authors.initials: SS
authors.lastname: Hann
authors.forename: Fang
authors.initials: F
authors.lastname: Zheng
authors.forename: Shunyu
authors.initials: S
authors.lastname: Zhao
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000111:Acetylcysteine / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism*; D047493:PPAR alpha / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: C000631429:PDK1 protein, human; D047493:PPAR alpha; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D051996:Transcription Factor RelA; D016159:Tumor Suppressor Protein p53; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578562:PDPK1 protein, human; D017346:Protein Serine-Threonine Kinases; D000111:Acetylcysteine