中文摘要：

目的探讨在苯并[a]芘（B[a]P）诱导的人胚肺成纤维细胞（HELF）中p53蛋白对p21、cyclinD1和CDK4蛋白间相互作用的影响。方法向转染p53小干扰RNA（p53siRNA）质粒的HELF细胞即p53．H细胞组、载体CMV的HELF细胞即HELF／CMV细胞组中分别加入2ixmol／LB[a]P作用24h，向p53化学抑制剂Pifithrin-α（PFT-α）组即HELF／CMV＋PFT．Ot细胞组中同时加入2μmol／LB[a]P和20μmol／LPFT-α作用24h，各组同时设立不做任何处理的对照组。用免疫印迹（Westernblot）法检测细胞中p53、p53-ser20以及p21、cyclinD1和CDK4蛋白水平的变化，同时利用免疫沉淀方法分析p53蛋白对p21、cyclinD1以及CDK4蛋白间相互作用的影响。结果利用PFT-α或p53siRNA技术抑制p53蛋白后，B[a]P诱导的p53蛋白20位丝氨酸磷酸化水平和p21蛋白水平的增高受抑制，B[a]P诱导的cyclinD1水平的增加不受影响，CDK4的水平不受B[a]P的影响；免疫沉淀实验结果表明，B[a]P引起的p21和CDK4结合的增加受到抑制，B[a]P引起的p21与cyclinD1结合的增加不受影响，cyclinD1和CDK4的结合不受B[a]P的影响。结论B[a]P通过p53-ser20影响人胚肺成纤维细胞p21和CDK4的结合。

英文摘要：

Objective To investigate the roles of p53 in the interaction of p21, cyclin D1 and CDK4 in human embryonic lung fibroblasts （HELFs） induced by benzo （a） pyrene. Methods p53-H group （cells transfected with p53 small interference RNA plasmid, p53 siRNA） and HELF/CMV group （cells transfected with CMV vector） were treated with 2 txmol/L B [ a]P for 24 h, and HELF/CMV ＋ PFT-α group （HELF/CMV cells were treated with p53 chemical inhibitor, Pifithrin-α） was treated with 2 ixmol/L B [a]P and 20 μmol/L PFT-α for 24 h. The above three groups set up control groups, respectively. Western blot assay was used to check the levels of p53, phosphorylated p53 at 20 site （p53-ser20）, p21, cyclin D1 and CDK4. Immunopreeipitation assay was used to investigate the roles of p53 in the interaction of p21, cyclin D1 and CDK4. Results After inhibition of p53 using PFT-α or siRNA, the high levels of p53, p53-ser 20 and p2! induced by B [ a]P were markedly decreased. The change of cyelin D1 level was not obsevered and the level CDK4 was free of B[ a]P. The combination of p21 and CDK 4 was increased after HELFs exposed to B [ a] P, which can not be observed after inhibition p53. The combination of p21 and cyelin D1 was increased with or without the expression of p53 after HELFs exposed to B[a]P. The combination of eyclin D1 and CDK 4 was not affected by B [ a]P. Conclusion p53 can affect the combination of p21 and CDK4 in HELFs induced by B[ a]P.