title: [Irradiation induced epithelial-mesenchymal transition in nasopharyngeal carcinoma in vitro].
abstract: OBJECTIVE
  To investigate the irradiation induced epithelial-mesenchymal transition (EMT) in nasopharyngeal carcinoma (NPC) in vitro.
  
  
  METHODS
  NPC CNE-2 cells with radioresistance (CNE-2-Rs) were established by exposure to gradiently increased dose of irradiation. CCK-8 cell viability kits, colony formation assay and fluorescence-activated cell sorting analysis were used to confirm the capacity of radioresistance of CNE-2-Rs cells. Invert microscope was used to monitor the morphological changes and western blot was applied to detect the expression of epithelial cell marker E-cadherin and mesenchymal cell marker Vimentin during the phase of CNE-2 exposure to irradiation.
  
  
  RESULTS
  Irradiation exposure successfully induced the radioresistance of CNE-2 cells. After exposed to irradiation, the survival rate in CNE-2-Rs was higher than that in CNE-2 by CCK-8 assays. No significant difference of proliferation ability was observed between the CNE-2 and CNE-2-Rs pre-radiotherapy, but a higher proliferation ability in the CNE-2-Rs post-radiotherapy. By using the colony forming assay, the parameters of CNE-2 and CNE-2-Rs in multi-target single-hit and linear quadratic model were obtained and the data demonstrated that parameters mean lethal dose (D0) , quasi-thres hold dose (Dq) , surrival fraction in 2Qy (SF2) and mean inctivation dose (MID) value increased, α and α/β value decreased (P < 0.05) . At the same time, the CNE-2-Rs cells showed higher percentage of cells in S and G2 phase (P < 0.05) . In terms of biomorphology, CNE-2-Rs cells were more narrow, long strips or fusiform shapes, stretched out tentacles, and the contacts between them were loosened. When radiation dose accumulated to 24 Gy, an over-expression of Vimentin was observed in treated cells, while E-cadherin was down-regulated (P < 0.01) .
  
  
  CONCLUSIONS
  NPC cells present with typical morphorlogical and biomolecular changes of EMT during exposure to irradiation, indicating the potential critical roles of EMT in the malignant behavior of radioresistance in NPC.
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Guo
authors.initials: G
authors.lastname: Li
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Zhong-wu
authors.initials: ZW
authors.lastname: Su
authors.forename: Shu-ling
authors.initials: SL
authors.lastname: Ren
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.forename: Yong-quan
authors.initials: YQ
authors.lastname: Tian
authors.forename: Yuan-zheng
authors.initials: YZ
authors.lastname: Qiu
mesh_terms: D015820:Cadherins; D002277:Carcinoma; D045744:Cell Line, Tumor; D002470:Cell Survival; D015536:Down-Regulation; D058750:Epithelial-Mesenchymal Transition; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D014746:Vimentin / Q000378:metabolism
chemical_list: D015820:Cadherins; D014746:Vimentin