A correlation study of single nucleotide polymorphisms in XRCC3,HOGG1 gene of repair DNA and radiosensitivity in esophageal squamous cell carcinoma / 中华放射肿瘤学杂志

Objective To study the relationship between the single nucleotide polymorphisms (SNP)of X-ray repair cross-complementing group-3(XRCC3),human 8-hydroxyguanine glycosylase-1 (HOGG1)gene of repair DNA and the radiosensitivity in esophageal squamous cell carcinoma(ESCC).Methotis Genome DNA was exracted from whole blood cells of ESCC patients.XRCC3 and HOGG1 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism method.The relationship was analyzed between SNP of XRCC3 Thr242 Met,HOGG1 Ser326 Cys and the response to radiotherapy in ESCC.Results Totally 199 ESCC patients were treated with radical radiotherapy.The response rate w88 81.4%.The response rate in patients with the XRCC3 Thr/Met genotype was significant higher than that in patients with Thr/Thr genotype(91.5%vs 77.1%,X2=5.67,P=0.017),with the same in HOGGlSet/Ser,Ser/Cys and Cys/Cys genotype(74.1%,84.2%,83.9%,X2=2.64,P=0.268).The esophageal radioactivity injury rate in patients with the XRCC3 Thr/Met genotype was also significant higher than that in patients with Thr/Thr genotype(35.6%vs 20.0%,X2=5.44,P= 0.020),with the same in HOGG1 Ser/Ser,Ser/Cys and Cys/Cys genotype(24.1%,24.6%,25.8%,X2=0.03,P=0.984).In Iogistic multivariate analysis,the SNP of XRCC3 was the independent influencing factor closely correlating with the mdiosensitivity of esophageal cancer(X2=16.12,4.43,P=0.009.0.035).No significant difierence was observed between the SNP in HOGG1 Ser326 Cys and the response rate of radiotherapy or the rate of esophageal radioactivity injury(X2=3.74,0.58,P=0.053,0.445).Conclusions SNP of XRCC3 Thr/Met is associated with the radiosensitivity in ESCC patients,which suggests that the XRCC3 Thr/Met SNP may be a predictor for ESCC patients who likely to response to radiotherapy.

Rapid Loss of Apurinic/Apyrimidinic Endonuclease and Subsequent Apoptosis in Kainate-Induced Seizure Model / 대한간질학회지

PURPOSE: The DNA repair enzyme, apurinic/apyrimidinic endonuclease (APE) plays a role in base excision repair pathway involved in repairing apurinic/apyrimidinic (AP) site after oxidative stress. To reveal the relationship between APE and neuronal apoptosis associated with oxidative stress after kainate treatment, the temporal change of APE expression was investigated in kainate-induced seizure model. METHODS: Status epilepticus was induced by unilateral intrahippocampal injection of kainate. Superoxide anion radical production and DNA oxidation were evaluated by in situ detection of oxidized hydroethidine and 8-hydroxyguanine (8-OHG) immunore activity. APE expression was examined by Western blot and immunohistochemical analysis. DNA fragmentation was visualized with terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) staining. RESULTS: Cell loss occurred at 24 hr in CA1, CA2, and CA3 after kainate-injection. 8-OHG immunoreactivity and oxidized hydroethidine were increased comparing with control after kainate-injection. APE immunoreactivity was decreased 4 and 24 hours in the hippocampus after kainate-injection. TUNEL-positive cells were observed 24 hours but not 4 hours in hippocampus after kainate-injection. In double labeling with APE and TUNEL, TUNEL-positive cells did not show APE immunoreactivity. These data showed that cellular oxidative stress was increased, thereby APE was decreased in the hippocampus after kainate-injection. Also, it was shown that the reduction of APE preceded DNA fragmentation. CONCLUSION: This study suggests that rapid loss of APE may produce the failure of DNA repair-machinary and then induce neuronal apoptosis following kainate-injection.

Effects of Exposure to Hexavalent Chromium on the Level of 8-Hydroxydeoxyguanosine and the Activities of Superoxide Dismutase and 8-Hydroxyguanine Endonuclease in Rat Lung / 예방의학회지

OBJECTIVES: To determine the effects of exposure to hexavalent chromium, 93 male Sprague-Dawley rats were exposed to hexavalent chromium solution. METHODS: Rats were divided into 4 groups and exposed to 0.1 ml of 0 mM, 0.4 mM, 2.0 mM, and 10.0 mM potassium chromate in the first experiment, and to 0.1 ml of 0 mM, 20 mM, 40 mM, and 80 mM in the second for consecutive 3 days by tracheal instillation. Three and 10 rats were the controls for the first and the second experiments, respectively. Lung tissues were then removed to measure the 8-hydroxydeoxyguanosine (8-OH-dG) level using the HPLC-ECD method, superoxide dismutase (SOD) activity using the cytochrome C method, and 8-hydroxyguanine endonuclease activity using the oligonucleotide nicking assay. RESULTS: The results showed no significant linear relationship between chromium exposure level and 8-OH-dG level or 8-hydroxyguanine endonuclease activity. In the first experiment, 8-OH-dG level and 8-hydroxyguanine endonuclease activity increased in 0.4 mM group, and then decreased in 2.0 mM and 10.0 mM groups. The correlation coefficients between 8-OH-dG level and 8-hydroxyguanine endonuclease activity was statistically significant (P<0.01), and total SOD activity was elevated by chromium exposure in a dose-dependent manner (P<0.05). In contrast, there was no significant dose-response pattern or correlation in the second experiment. CONCLUSIONS: Based on the fact that there was no linear relationship between chromium dose and 8-OH-dG level or activity of the repair enzyme, it seems unlikely that 8-OH-dG formation is the major mechanism of chromium carcinogenesis.