title: Downregulation of apurinic/apyrimidinic endonuclease 1/redox factor-1 enhances the sensitivity of human pancreatic cancer cells to radiotherapy in vitro.
abstract: Abstract Background: Radiotherapy is an important treatment for the patients with advanced pancreatic cancer. Emerging studies determined apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) might associate with the resistance of human pancreatic cancer cells to radiotherapy.
  
  
  OBJECTIVE
  To investigate whether downregulation of APE1/Ref-1 expression by ribonucleic acid interference would increase the sensitivity of chromic-P32 phosphate to pancreatic cancer cells.
  
  
  METHODS
  The plasmids containing APE-specific and unspecific short hairpin were transfected into Patu-8898 cells. Stable cell clones were selected by G418. The mRNA expression of APE1/Ref-1 was detected by semiquantitative reverse transcription-polymerase chain reaction and the protein expression of APE1/Ref-1 was detected by Western blot analysis; cell proliferation was studied by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and colony formation assay; apoptosis was detected by flow cytometry.
  
  
  RESULTS
  After 24 hours irradiation, APE1/Ref-1 mRNA and protein expression were upregulated, in a concentration-dependent manner. Suppression of APE1/Ref-1 by siRNA increased the pancreatic cancer cells hypersensitive to (32)P-CP. In the combination of (32)P-CP and siRNA group, MTT assay showed that the cell inhibition increased to (74.33%±9.02%), the surviving fraction in the colony formation assay was only 25.00%, and the apoptosis rate was up to (16.77%±0.98%).
  
  
  CONCLUSIONS
  Knockdown APE1/Ref-1 gene expression may significantly sensitize the Patu-8988 cells to radiotherapy, which may be a useful target for modifying radiation resistance of pancreatic cancer cells to irradiation.
authors.affiliation: Division of Gastroenterology and Hepatology, Shanghai Institute of Digestive Disease, Shanghai Jiao-Tong University School of Medicine Renji Hospital, Shanghai, China.
authors.forename: Sumei
authors.initials: S
authors.lastname: Chen
authors.forename: GuangSu
authors.initials: G
authors.lastname: Xiong
authors.forename: Shuming
authors.initials: S
authors.lastname: Wu
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Mo
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D015153:Blotting, Western; D049109:Cell Proliferation / Q000528:radiation effects*; D017608:Chromium Compounds / Q000494:pharmacology*; D003114:Colony-Forming Units Assay; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D010710:Phosphates / Q000494:pharmacology*; D010761:Phosphorus Radioisotopes / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D011836:Radiation Tolerance / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D017608:Chromium Compounds; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C509369:chromic phosphate; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase