title: [PPAR-γ silencing inhibits the apoptosis of A549 cells by upregulating Bcl-2].
abstract: BACKGROUND
  Drug resistance is the one of primary causes of death in patients with lung cancer, PPAR-γ could induce the apoptosis and reverse drug resistance. The aim of this study is to investigate the expression of PPAR-γ on cisplatin sensitivity and apoptosis response of human lung cancer cell line A549.
  
  
  METHODS
  Reconstruction of PPAR-γ silencing A549 cells (A549/PPAR-γ(-)) by siRNA. MTT assay was employed to determine the effect of cisplatin on the proliferation of A549/PPAR-γ(-), flow cytometry to determine the effect of cisplatin on the cell apoptosis, Western blot to determine the change of phosphorylation of Akt, caspase-3 and expression of bcl-2/bax. Finally, RT-PCR was employed to determine the transcriptional level of bcl-2.
  
  
  RESULTS
  Two PPAR-γ silencing A549 cell clones were established successfully, and the expression of PPAR-γ was downregulated significantly as confirmed by RT-PCR and Western blot. After PPAR-γ silencing, the resistance of these two A549 clones to cisplatin was increased by 1.29-fold and 1.60-fold respectively. Flow cytometry showed that the apoptosis rate was decreased, and Western Blot showed that the phosphorylation of Akt and expression of bcl-2/bax were upregulated, caspase-3 was downregulated. Finally, RT-PCR showed that the transcriptional level of bcl-2 was upregulated as well.
  
  
  CONCLUSIONS
  Downregulation of PPAR-γ in A549 cells led to increase of cisplatin resistance. One of the mechanisms was upregulatin of phosphorylation of Akt and expression of bcl-2, which inhibited the apoptosis of cells. The downregulation of PPAR-γ is a possible mechanism that leads to the clinical drug resistance of cancer.
authors.affiliation: Graduate School of Tianjin Medical University, Tianjin 300070, China. xiexiaoyuan2001@163.com
authors.forename: Jingyu
authors.initials: J
authors.lastname: Yang
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D020868:Gene Silencing; D006801:Humans; D047495:PPAR gamma / Q000172:deficiency* / Q000235:genetics*; D010766:Phosphorylation / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D047495:PPAR gamma; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3