title: Downregulating sCLU enhances the sensitivity of hepatocellular carcinoma cells to gemcitabine by activating the intrinsic apoptosis pathway.
abstract: OBJECTIVE
  The purpose of this study was to investigate whether the therapeutic activity of gemcitabine (GCB) in hepatocellular carcinoma (HCC) could be increased by the down-regulation of secretory clusterin (sCLU), a glycoprotein that is considered to play a cytoprotective role in the resistance to chemotherapy.
  
  
  METHODS
  The expression of sCLU was detected in HCC tumor tissues and cell lines. A cell viability and apoptosis assay were performed in parental HCC cells or the same cells transfected with sCLU shRNA and treated with or without GCB. The potential downstream pathways were investigated using the Human Apoptosis RT(2) Profiler™ PCR Array.
  
  
  RESULTS
  The expression levels of sCLU in HCC tissues were significantly higher than in adjacent non-tumor liver tissues and were associated with the histological grade and transarterial chemoembolization. sCLU overexpression was also found in three HCC cell lines and hepatocytes. The depletion of sCLU synergistically increased GCB sensitivity in Bel7402 and SMMC7721 cells and induced cell apoptosis. Based on the PCR array analysis, sCLU depletion also resulted in the up-regulation of BNIP1, GADD45A, TNFRSF10A, and TRADD and down-regulation of AKT1 in Bel7402 and SMMC7721 cells compared with the parental controls. These results were further supported by a Western blot analysis, which showed increased GADD45a protein expression and the decreased expression of phosphorylated AKT. GADD45a overexpression also increased the sensitivity to GCB in the Bel7402 and SMMC7721 cells.
  
  
  CONCLUSIONS
  Targeting sCLU may be a useful method to enhance the cytotoxic effect of GCB in hepatocellular carcinoma.
authors.affiliation: Department of General Surgery, Qianfoshan Hospital, Shandong University, Jinan, 250014, China, lcxiupeng@126.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Xiu
authors.forename: Zongzhen
authors.initials: Z
authors.lastname: Xu
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Fang
authors.initials: F
authors.lastname: Zou
authors.forename: Xueying
authors.initials: X
authors.lastname: Sun
authors.forename: Jie
authors.initials: J
authors.lastname: Li
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins / Q000378:metabolism; D051152:Clusterin / Q000378:metabolism*; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism; D000093542:Gemcitabine; D000097642:GADD45 Proteins
chemical_list: D000964:Antimetabolites, Antineoplastic; D018797:Cell Cycle Proteins; D051152:Clusterin; D003841:Deoxycytidine; D009687:Nuclear Proteins; D000093542:Gemcitabine; C439070:GADD45A protein, human; D000097642:GADD45 Proteins