title: The effects of 12C6+ irradiation on cell cycle, apoptosis, and expression of caspase-3 in the human lung cancer cell line h1299.
abstract: BACKGROUND
  We aimed to investigate the effects of (12)C(6+) irradiation on the cell cycle and apoptosis as well as the associated mechanisms in the human lung cancer cell line H1299.
  
  
  METHODS
  After irradiation with different doses of (12)C(6+) for varying lengths of incubation, the changes in H1299 cells were assayed by flow cytometry and the microculture tetrazolium test. The expression of caspase-3 was detected by immunocytochemistry, western blot, and reverse transcription-polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  The G(2)/M phase was blocked after treatment with 1 and 2 Gy at the 12-hour time point, and the most obvious block of G(2)/M occurred after treatment with 2 and 4 Gy at the 24-hour time point in a dose-dependent manner. The apoptosis rate increased with increasing radiation dose and reached a peak after the cells were irradiated with 2 Gy and incubated for 48 hours. In addition, the RT-PCR, western blot, and ICC results showed that irradiation with (12)C(6+) significantly increased the expression of caspase-3 compared with the control group (p<0.05).
  
  
  CONCLUSIONS
  Irradiation of H1299 cells with (12)C(6+) induced apoptosis and significantly inhibited their growth through heavy ion irradiation-mediated activation of the caspase-3 pathway. Our results show that caspase-3 may play an important role in radiation-induced apoptosis through a p53-independent pathway.
authors.affiliation: School of Life Sciences, Lanzhou University, PR China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
authors.forename: Lan
authors.initials: L
authors.lastname: Gao
authors.forename: Tuanjie
authors.initials: T
authors.lastname: Che
authors.forename: Wenjing
authors.initials: W
authors.lastname: Du
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Qingxiang
authors.initials: Q
authors.lastname: Gao
authors.forename: Ziren
authors.initials: Z
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D002247:Carbon Isotopes / Q000008:administration & dosage*; D053148:Caspase 3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects; D016195:G2 Phase / Q000528:radiation effects; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*
chemical_list: D002247:Carbon Isotopes; D053148:Caspase 3