title: Microarray analysis of DNA damage repair gene expression profiles in cervical cancer cells radioresistant to 252Cf neutron and X-rays.
abstract: BACKGROUND
  The aim of the study was to obtain stable radioresistant sub-lines from the human cervical cancer cell line HeLa by prolonged exposure to 252Cf neutron and X-rays. Radioresistance mechanisms were investigated in the resulting cells using microarray analysis of DNA damage repair genes.
  
  
  METHODS
  HeLa cells were treated with fractionated 252Cf neutron and X-rays, with a cumulative dose of 75 Gy each, over 8 months, yielding the sub-lines HeLaNR and HeLaXR. Radioresistant characteristics were detected by clone formation assay, ultrastructural observations, cell doubling time, cell cycle distribution, and apoptosis assay. Gene expression patterns of the radioresistant sub-lines were studied through microarray analysis and verified by Western blotting and real-time PCR.
  
  
  RESULTS
  The radioresistant sub-lines HeLaNR and HeLaXR were more radioresisitant to 252Cf neutron and X-rays than parental HeLa cells by detecting their radioresistant characteristics, respectively. Compared to HeLa cells, the expression of 24 genes was significantly altered by at least 2-fold in HeLaNR cells. Of these, 19 genes were up-regulated and 5 down-regulated. In HeLaXR cells, 41 genes were significantly altered by at least 2-fold; 38 genes were up-regulated and 3 down-regulated.
  
  
  CONCLUSIONS
  Chronic exposure of cells to ionizing radiation induces adaptive responses that enhance tolerance of ionizing radiation and allow investigations of cellular radioresistance mechanisms. The insights gained into the molecular mechanisms activated by these "radioresistance" genes will lead to new therapeutic targets for cervical cancer.
authors.affiliation: Cancer Center, Daping Hospital and Research Institute of Surgery, Third Military Medical University, Chongqing, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Qing
authors.forename: Xue-Qin
authors.initials: XQ
authors.lastname: Yang
authors.forename: Zhao-Yang
authors.initials: ZY
authors.lastname: Zhong
authors.forename: Xin
authors.initials: X
authors.lastname: Lei
authors.forename: Jia-Yin
authors.initials: JY
authors.lastname: Xie
authors.forename: Meng-Xia
authors.initials: MX
authors.lastname: Li
authors.forename: De-Bing
authors.initials: DB
authors.lastname: Xiang
authors.forename: Zeng-Peng
authors.initials: ZP
authors.lastname: Li
authors.forename: Zhen-Zhou
authors.initials: ZZ
authors.lastname: Yang
authors.forename: Ge
authors.initials: G
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
mesh_terms: D017209:Apoptosis; D002453:Cell Cycle; D045744:Cell Line, Tumor; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D009502:Neutrons; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D002583:Uterine Cervical Neoplasms / Q000378:metabolism* / Q000532:radiotherapy*; D014965:X-Rays