苯并(a)芘对肺癌细胞DNA损伤及修复基因表达水平的影响

Effect of benzopyrene on DNA damage and expression of genes involved in nucleotide excision repair in lung cancer cells

目的 探讨苯并 (a)芘 (BaP)对肺癌细胞DNA损伤及核酸切除修复 (NER)基因———着色性干皮病B、C、G基因 (XPB、XPC、XPG)和切除修复交叉互补基因 1 (ERCC1 )表达的影响。方法 以噻唑蓝(MTT)法检测BaP对细胞的毒作用 ,单细胞凝胶电泳检测DNA损伤情况 ,逆转录聚合酶链反应 (RT PCR)检测基因表达水平。结果 BaP(0 .62 5～ 2 0 .0 0 0 μmol/L)处理肺癌A549细胞 2 4h ,细胞生存力从 95.0 %降至 70 .0 %。1 0 μmol/LBaP处理 1 2、2 4h ,细胞生存力分别降至 87.0 %、73.0 % ,DNA损伤逐渐加重 ;BaP染毒2 4h后孵育 1 2h ,细胞生存力降至 59.0 % ,DNA损伤最严重 ;继续孵育至 2 4h ,细胞生存力恢复至 71 .0 % ,DNA损伤逐渐修复。BaP处理引起XPB和XPC基因表达升高 ,在染毒 2 4h和染毒后 1 2h达峰值 ,分别为基底水平的 4.5和 1 1 .2倍 ,随后逐渐下降 ;XPG和ERCC1基因在染毒期间表达下降 ,染毒结束后逐渐恢复。结论 BaP导致肺癌A549细胞DNA损伤 。

Objective To investigate the effect of benzo pyrene(BaP) on DNA damage and expression of genes involved in nucleotide excision repair[xeroderma pigmentosum group B?C?G(XPB?XPC?XPG) and excision repair cross complementing 1(ERCC1)] in lung cancer A549 cells. Methods Cell survival was measured using MTT metabolic viability assay.Single cell gel assay was applied to determine the DNA damage and repair.The level of gene expression was measured by reverse transcription polymerase chain reaction. Results The cell survival decreased from 95.0% to 70.0% after 24 h treatment with BaP of varying concentration ranging 0.625～ 20.000 μmol/L .The cell survival decreased to 87.0% and 73.0% respectively after 12 h and 24 h treatment with 10 μmol/L BaP,with DNA damage gradually elevated.At 12 h after 24 h treatment,the cell survival further decreased to 59.0% and DNA damage became most serious.At 24 h after 24 h treatment,cell survival recovered to 71.0%,and damaged DNA was repaired gradually.XPB and XPC gene expression increased to 4.5 fold and 11.2 fold respectively compared with basal level at 24 h treatment or 12 h after 24 h treatment with 10 μmol/L BaP respectively.However,ERCC1 and XPG gene expression was inhibited in 24 h treatment period,then recovered gradually after treatment. Conclusion Benzopyrene could lead to DNA damage and expression level change of genes involved in nucleotide excision repair in lung cancer A549 cells.