title: Effects of cyclin-dependent kinase 8 specific siRNA on the proliferation and apoptosis of colon cancer cells.
abstract: BACKGROUND
  To investigate the expression of cyclin-dependent kinase 8 (CDK8) and β-catenin in colon cancer and evaluate the role of CDK8 in the proliferation, apoptosis and cell cycle progression of colon cancer cells, especially in HCT116 cell line.
  
  
  METHODS
  Colon cancer cell line HCT116 was transfected with small interfering RNA (siRNA) targeting on CDK8. After CDK8-siRNA transfection, mRNA and protein expression levels of CDK8 and β-catenin were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot assay in HCT116 cells. Cell proliferation was measured by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide Methylthiazolyl tetrazolium (MTT) assay, and cell cycle distribution and apoptosis were analyzed by flow cytometry analysis (FACS). CDK8 and β-catenin protein levels were also examined by real-time PCR and immunohistochemistry (IHC) in colon cancer tissues and adjacent normal tissues.
  
  
  RESULTS
  After CDK8 specific siRNA transfection, mRNA and protein expression levels of CDK8 and β-catenin in HCT116 cells were noticeably decreased (P < 0.05). CDK8 specific siRNA transfection inhibited HCT116 cells' proliferation and facilitated their apoptosis significantly (P < 0.05). In addition, the proportion of HCT116 cells in the G0/G1 phase was remarkably increased after CDK8-siRNA transfection (P < 0.05). The expression levels of CDK8 and β-catenin in adjacent normal tissues were lower than in tumor tissues (P < 0.05). Moreover, the expression of CDK8 was correlated with the expression of β-catenin in both tumor and adjacent normal tissues (P < 0.05).
  
  
  CONCLUSIONS
  CDK8 and β-catenin were expressed in colon cancer at a high frequency. CDK8 specific siRNA transfection down-regulated the expression of CDK8 in colon cancer cells, which was also associated with a decrease in the expression of β-catenin Moreover, CDK8 specific siRNA inhibited the proliferation of colon cancer cells, promoted their apoptosis and arrested these cells in the G0/G1 phase. Interference of CDK8 might be an effective strategy through β-catenin regulation of colon cancer.
authors: Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China.
authors: Song-Bing
authors: SB
authors: He
authors: Yin
authors: Y
authors: Yuan
authors: Lei
authors: L
authors: Wang
authors: Min-Jing
authors: MJ
authors: Yu
authors: Yi-Bei
authors: YB
authors: Zhu
authors: Xing-Guo
authors: XG
authors: Zhu
mesh_terms: D017209:Apoptosis / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D056850:Cyclin-Dependent Kinase 8 / Q000096:biosynthesis / Q000235:genetics*; D015870:Gene Expression; D045325:HCT116 Cells; D006801:Humans; D007150:Immunohistochemistry; D034741:RNA, Small Interfering / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D051176:beta Catenin / Q000096:biosynthesis / Q000235:genetics
chemical_list: D034741:RNA, Small Interfering; D051176:beta Catenin; D056850:Cyclin-Dependent Kinase 8