title: Inhibiting XIAP expression by RNAi to inhibit proliferation and enhance radiosensitivity in laryngeal cancer cell line.
abstract: OBJECTIVE
  X-linked inhibitor of apoptosis protein (XIAP) is a novel member of the inhibitors of apoptosis (IAPs) family. The overexpression of XIAP is asscociated with radioresistance of human malignancies. The purpose of the present study was to investigate the effect of shRNA-targeted XIAP on the proliferation, apoptosis and radiosensitivity of human laryngeal carcinoma cells (Hep-2).
  
  
  METHODS
  A siRNA expression vector (pSilencer4.1-XIAPshRNA) was constructed and stably transfected into human laryngeal carcinoma cells (Hep-2). The downregulation of XIAP expression was evaluated by RT-PCR and Western blot analyses. Then, we investigated the effect of XIAP-shRNA on the proliferation, cell cycle changes and apoptosis in vitro of Hep-2 cells. Finally, the radiosensitivity of Hep-2 cells was investigated by clonogenic cell survival assay.
  
  
  RESULTS
  We established stably transfected cell line (Hep-2/XIAPshRNA) in which the expression of XIAP gene was downregulated. The cell viability of Hep-2/XIAP-RNA cells was obviously decreased compared with that of untransfected Hep-2 cells. Morever, XIAP-shRNA induced cell arrest in the G(0)/G(1) phase of cell cycle by flow cytometry analysis. Results of TUNEL assay indicated that Hep-2 cells stably transfected pSilencer4.1-XIAP-shRNA showed obvious apoptosis characters. Furthermore, the downregulation of XIAP expression could lead to significant radiosensitivity enhancement in laryngeal carcinoma cells.
  
  
  CONCLUSIONS
  RNAi-mediated downregulation of XIAP expression can inhibit proliferation, induce apoptosis and diminish the radioresistance of laryngeal carcinoma cells, so combined therapy with XIAP inhibition and radiation may be a potential strategy for the treatment of laryngeal carcinoma.
authors.affiliation: Clinical Laboratory Department, Tangdu Hospital, Fourth Military Medical University, Xinsi Road, 710038 Xi'an, Shaanxi Province, PR China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Lin
authors.forename: Ping
authors.initials: P
authors.lastname: Gao
authors.forename: Shi-Yin
authors.initials: SY
authors.lastname: Cheng
authors.forename: Hui-Zhong
authors.initials: HZ
authors.lastname: Zhang
mesh_terms: D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002277:Carcinoma / Q000235:genetics* / Q000628:therapy*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D007822:Laryngeal Neoplasms / Q000235:genetics* / Q000628:therapy*; D034622:RNA Interference; D011836:Radiation Tolerance; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human