HSP70在苯并(a)芘致细胞DNA损伤中的保护作用

Heat Shock Protein 70 Protects Against DNA Damage of A549 Cells Caused by Benzo(a)pyrene

[目的]研究热休克蛋白70(HSP70)对苯并(a)芘[B(a)P]所致肺腺癌细胞A549的DNA损伤的保护作用。[方法]用含HSPTO基因cDNA的pcDNA3．0／HSP70重组质粒转染A549细胞,提高A549细胞HSP70表达水平,以空载体质粒pcDNA3．0转染作载体对照。对肺腺癌A549细胞(A549)、空载体质粒pcDNA3．0转染A549细胞(A549／pcDNA)和HSP70过表达A549细胞(A549／HSP70),用不同浓度的B(a)P(1、5、10、50、100μmol／L)染毒24h,MTT法测定细胞存活率、单细胞琼脂糖凝胶电泳检测细胞DNA损伤。用溶剂二甲基亚砜处理细胞组作为未染毒细胞组。[结果]B(a)P染毒作用时,A549/HSP70细胞在50、100μmol／L浓度组存活率明显高于A549细胞。A549、A549／pcDNA和A549/HSP70细胞的DNA损伤程度都伴随B(a)P染毒浓度增加而增加。与各自未染毒细胞相比,染毒A549和A549／pcDNA细胞的Olive尾矩值均有明显增加(P<0．05),A549／HSP70细胞在5、10、50、100μmol／L浓度时,Olive尾矩值明显升高(P<0．05)。与A549细胞组相比,在各染毒浓度下,A549/HSP70细胞Olive尾矩值均有降低(P<0．05)。A549／pcDNA细胞Olive尾矩值均无明显改变。[结论]HSP70对苯并(a)芘所致肺腺癌细胞A549的DNA损伤具有保护作用。

[ Objective ] To investigate whether HSP70 plays a role in the protection against DNA damage by B（a）P. [ Methods ] The A549 cells were transfected with the recombinant peDNA3.0 plasmid containing HSP70 eDNA as test group. Control cells were transfected with pcDNA3.0 plasmid without HSP70 eDNA but still containing the neomycin resistance gene. Transfected A549 with empty peDNA3.0 （ A549/peDNA cells ） and HSP70 overexpressing A549 cells （ A5491HSP70 cells ） were exposed to different concentrations of benzo（a）pyrene [ 1, 5, 10, 50, 100 μmol/L B（a）P ]. DNA damage was detected with alkaline singl-cell gel electrophoresis, and the cell viability was measured by Mqq＇ assay. [ Results ] A549/HSP70 cells had a significant increased viability compared with A549 cells （ P 〈 0.05 ） in high concentrations of B（a）P （ 50, 100 μmol/L ）. There were dose-dependent increases in DNA damage in all A549, A549/pcDNA and A549/HSPTO cells exposed to B（a）P. The OTM values in A549, A549/pcDNA cells exposed to 1, 5, 10, 50, 100ttmol/L B（a）P all increased significantly compared with the groups not exposed to B（a）P, respectively（ P 〈 0.05 ）. The OTM values in A549/HSPTO cells exposed to 5, 10, 50, 100 gmol/L B（a）P increased significantly compared with the group not exposed to B（a）P（ P 〈 0.05 ）.Nevertheless, OTM values in A549/HSP70 cells significantly decreased in B（a）P treatment groups compared to A549 cells with the same treatment of B（a）P（ P 〈 0.05 ）, but no marked difference was found in A549/pcDNA cells. [ Conclusion ] It was suggested that HSP70 has some protection against DNA damage of A549 cells caused by benzo（a）pyrene.