title: Induction of pancreatic cancer cell apoptosis and enhancement of gemcitabine sensitivity by RAP80 siRNA.
abstract: BACKGROUND
  Receptor-associated protein 80 (RAP80) increases substantially in pancreatic cancer. The involvement of RAP80 in the chemoresistance of pancreatic cancer should be elucidated.
  
  
  OBJECTIVE
  We investigated the effects of inhibiting RAP80 expression on the sensitivity of pancreatic cancer cells to gemcitabine chemotherapy by using small interfering RNA (siRNA).
  
  
  METHODS
  Chemically synthesized siRNA RAP80 was transfected into human pancreatic cancer cell lines SW1990 and Capan-2. The IC(50) of gemcitabine was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis was detected by using flow cytometry. Expression of apoptosis-related genes, Bax, Bcl-2, TRAIL, survivin, and caspase-8 was detected by using reverse transcription-polymerase chain reaction (RT-PCR) and western blot.
  
  
  RESULTS
  Gemcitabine inhibits proliferation of SW1990 and Capan-2 cells in a concentration-dependent manner. Inhibition of RAP80 expression significantly reduced the IC(50) of gemcitabine (P < 0.01). RAP80 siRNA combined with gemcitabine significantly increased (P < 0.01) apoptosis of pancreatic cancer cell lines SW1990 and Capan-2, increased expression of Bax mRNA, reduced Bcl-2 mRNA expression (P < 0.01), and slightly increased TRAIL mRNA expression (P < 0.01). Correspondingly, in the RAP80 siRNA combined with gemcitabine group, both Bax and cleaved caspase-8 protein levels were increased (P < 0.01), whereas Bcl-2 protein decreased significantly (P < 0.01). No change in survivin mRNA expression was observed (P < 0.01).
  
  
  CONCLUSIONS
  Inhibition of RAP80 expression can induce apoptosis in pancreatic cancer cells and improve chemosensitivity to gemcitabine.
authors.affiliation: Department of Gastroenterology, The Ninth People's Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai 200011, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Li
authors.forename: Wen-Jun
authors.initials: WJ
authors.lastname: Gu
authors.forename: Hai-Lin
authors.initials: HL
authors.lastname: Liu
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004357:Drug Synergism; D015870:Gene Expression / Q000187:drug effects; D056488:Histone Chaperones; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors*; D010190:Pancreatic Neoplasms / Q000188:drug therapy*; D034741:RNA, Small Interfering / Q000494:pharmacology / Q000627:therapeutic use*; D014162:Transfection; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D056488:Histone Chaperones; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; C466234:UIMC1 protein, human; D003841:Deoxycytidine; D000093542:Gemcitabine