Relationship between NRAGE and the radioresistance of esophageal carcinoma cell line TE13R120.
OBJECTIVE
The mRNA levels of 59 genes, detected by cDNA microarray, were up-regulated in the radioresistant human esophageal cacinoma cell line TE13R120 as compared with its parental cell line TE13 before and after radiation, and the expression of NRAGE gene showed a gradually up-regulating tendency. This study aimed to further detect the differences of NRAGE gene and protein expression and apoptosis between TE13R120 and TE13 cells, and to investigate the relationship between the NRAGE and the radioresistance of TE13R120 cells and its mechanism.


METHODS
The two cell lines were irradiated by ⁶⁰Co γ-ray at different conditions. Reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunocytochemistry were used to detect the expression of NRAGE. Flow cytometry (FCM) was used to detect the cell apoptosis before and after irradiation.


RESULTS
The mRNA level of NRAGE was higher in TE13R120 cells than in TE13 cells before and after irradiation (before radiation: 0.25 ± 0.03 vs. 0.49 ± 0.03; 4 Gy 4 h: 0.31 ± 0.03 vs. 0.53 ± 0.02; 4 Gy 16 h: 0.32 ± 0.04 vs. 0.59 ± 0.04; 4 Gy 24 h: 0.36 ± 0.05 vs. 0.72 ± 0.04; 2 Gy 12 h: 0.32 ± 0.02 vs. 0.64 ± 0.04; 6 Gy 12 h: 0.36 ± 0.02 vs. 0.79 ± 0.05; 10 Gy 12 h: 0.46 ± 0.04 vs. 0.85 ± 0.01; P < 0.01), and the mRNA level of NRAGE was increased gradually with the increase of radiation dose and time in the two cell lines (P < 0.05 and P < 0.01). Western blot results showed no difference of NRAGE protein level in cytoplasm between TE13R120 cells and TE13 cells before and after irradiation, but its level in nuclei was higher in TE13R120 cells than in TE13 cells at different radiation time and dosages. Immunocytochemistry showed similar results as Western blot. FCM showed no significant difference in apoptosis rate between TE13R120 and TE13 cells before and after radiation.


CONCLUSIONS
NRAGE may play an important role in the radiation responses of the two cell lines, and may participate in the formation of radioresistance of TE13R120 cells by changing its subcellular localization, but its relationship with cell apoptosis has not been confirmed.
Xue
Xiao-Ying
XY
Department of Radiation Oncology, Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, PR China.
Liu
Zhi-He
ZH
Jing
Feng-Min
FM
Li
Yan-Ge
YG
Liu
Hui-Zhi
HZ
Gao
Xian-Shu
XS
D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D017209:Apoptosis / Q000528:radiation effects; D045744:Cell Line, Tumor / Q000528:radiation effects; D003037:Cobalt Radioisotopes; D004938:Esophageal Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism / Q000528:radiation effects; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D013997:Time Factors; D015854:Up-Regulation
D000951:Antigens, Neoplasm; D003037:Cobalt Radioisotopes; C120897:MAGED1 protein, human; D009363:Neoplasm Proteins; D012333:RNA, Messenger