title: [Correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cells].
abstract: OBJECTIVE
  Many studies showed that telomere length and telomerase activity closely correlate with proliferation and malignant degree of tumor cells, and both of them might be involved in the repair of radiation-induced DNA damage. So it was speculated that telomere length and telomerase activity maybe correlate to radiosensitivity of carcinoma cells. This study was designed to investigate the correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cell line Hep-2.
  
  
  METHODS
  Hep-2 cells were irradiated with 0, 2, 4, 8, or 12 Gy of gamma-ray for 3 times. Survival cells were subcultured for 20 generations. Radiosensitivity index, survival fraction at 2 Gy (SF(2)), was measured by clone formation assay. Telomere length (mean length of telomere restriction fragments, TRF) was examined by Southern blotû telomerase activity (TA) was detected by polymerase chain reaction-based telomeric repeat amplification protocol (PCR-TRAP) coupled with ELISA.
  
  
  RESULTS
  After different doses of irradiation, SF(2) of Hep-2 cells was 0.47-0.64; TRF was 3.76-9.43 kb; TA was 1.761-2.606. Each parameter had significant differences among the survival progenies (P<0.05). SF(2) was positively correlated with TRF (r=0.921, P<0.01), and negatively correlated with TA (r=-0.929, P<0.01); TRF was negatively correlated with TA (r=-0.944, P<0.01).
  
  
  CONCLUSIONS
  Radiosensitivity of Hep-2 cells negatively correlates with telomere length, and positively correlates with telomerase activity, which suggest that both telomere length and telomerase activity may be used to predict cellular radiosensitivity.
authors.affiliation: Department of Radiochemotherapy, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P. R. China.
authors.forename: Chuang-Ying
authors.initials: CY
authors.lastname: Xiao
authors.forename: Fu-Xiang
authors.initials: FX
authors.lastname: Zhou
authors.forename: Shi-Quan
authors.initials: SQ
authors.lastname: Liu
authors.forename: Cong-Hua
authors.initials: CH
authors.lastname: Xie
authors.forename: Jing
authors.initials: J
authors.lastname: Dai
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Zhou
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans; D007822:Laryngeal Neoplasms / Q000201:enzymology / Q000473:pathology; D011829:Radiation Dosage; D011836:Radiation Tolerance; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000528:radiation effects / Q000648:ultrastructure*
chemical_list: D019098:Telomerase