title: RNAi knockdown of the Akt1 gene increases the chemosensitivity of gastric cancer cells to cisplatin both in vitro and in vivo.
abstract: OBJECTIVE
  To examine the in vitro and in vivo effects of a combined treatment of cis-d iamminedichloroplatinum(II) (cisplatin) with downregulation of Akt1 expression in gastric cancer cells.
  
  
  METHODS
  Lentivirus-mediated RNA interference (RNAi) was used to silence the Akt1 gene. pGCSIL-Akt1 small hairpin RNA (shRNA) was stably transfected into gastric cancer cells (SGC7901 and BGC823). Next, the effects of Akt1 downregulation on the growth and apoptosis of SGC7901 (BGC823) cells in the presence or absence of cisplatin were investigated by real-time polymerase chain reaction (RT-PCR), Western blot analysis, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-d-iphenyltetrazolium bromide) assay, Hoechst assay, flow cytometric analysis of annexin V-FITC/PI staining, and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling). Finally, the effects of downregulation of Akt1 expression on the sensitivity of SGC7901 cells in a tumor xenograft model of cisplatin were also determined.
  
  
  RESULTS
  Akt1 silencing reduced gastric cancer proliferation and increased cell apoptosis both in vitro and in vivo. The chemosensitivity of SGC7901 (BGC823) cells to cisplatin increased significantly following the downregulation of Akt1 expression, which might be associated with the inactivation of the PI3K/Akt1 signaling pathway, followed by the induced expression of the pro-apoptotic protein Bax and a concomitant decrease of Bcl-2 expression.
  
  
  CONCLUSIONS
  This study confirmed that downregulation of Akt1 reduced chemotherapy tolerance of gastric cancer cells to cisplatin treatment. Thus, Akt1 silencing and cisplatin appear to be an effective combination treatment strategy for gastric cancer.
authors.affiliation: Department of Gastroenterology, Renmin Hospital of Wuhan University, 430060 Wuhan, China,
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Xue-Qiong
authors.initials: XQ
authors.lastname: Fu
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Hong-Gang
authors.initials: HG
authors.lastname: Yu
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D055785:Gene Knockdown Techniques; D006801:Humans; D016086:Lentivirus; D051057:Proto-Oncogene Proteins c-akt / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D002945:Cisplatin