Yang Di, Qi Yitao, Chen Qian, Wang Zhiqin, Jin Xi, Gao Jie, Fu Juanling, Xiao Xilong, Zhou Zongcan
Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, P.R. China.
Mol Cell Biochem. 2007 Oct;304(1-2):219-26. doi: 10.1007/s11010-007-9503-9. Epub 2007 May 26.
Down-regulation of p53 expression has been found in a broad range of human cancers and cell proliferation disorders, indicating that p53 plays a key role in cell cycle regulation and tumor suppression. In our current study, we transfected human embryonic lung fibroblast (HELF) cells with pcDNA3-wild-type p53 (pcDNA3-wtp53) plasmid, or pcDNA3-H179Y-mutated p53 (pcDNA3-mtp53) plasmid that mimics the mutation found in some human lung tumors, and further studied the role of p53 in the regulation of cell proliferation. Over expression of wild-type p53 caused cell cycle arrest at G1 phase with reduced cell size, decreased expression of cyclin D3, cyclin E, Cdk2 and Cdk4, and increased expression of p21. In contrast, over expression of H179Y-mutant p53 promoted G1 to S phase transition with enlarged cell size and increased cyclin A1 and Cdk4 expression in HELF cells. These results indicate that mutation at the p53 H179Y residue up-regulates cyclin A1 and Cdk4 expression, and promotes HELF cell proliferation.
在多种人类癌症和细胞增殖紊乱中均发现p53表达下调，这表明p53在细胞周期调控和肿瘤抑制中发挥关键作用。在我们当前的研究中，我们用pcDNA3-野生型p53（pcDNA3-wtp53）质粒或模拟某些人类肺癌中发现的突变的pcDNA3-H179Y-突变型p53（pcDNA3-mtp53）质粒转染人胚肺成纤维细胞（HELF），并进一步研究p53在细胞增殖调控中的作用。野生型p53的过表达导致细胞周期停滞在G1期，细胞大小减小，细胞周期蛋白D3、细胞周期蛋白E、细胞周期蛋白依赖性激酶2（Cdk2）和细胞周期蛋白依赖性激酶4（Cdk4）的表达降低，而p21的表达增加。相反，H179Y-突变型p53的过表达促进了HELF细胞从G1期到S期的转变，细胞大小增大，细胞周期蛋白A1和Cdk4的表达增加。这些结果表明，p53的H179Y残基处的突变上调了细胞周期蛋白A1和Cdk4的表达，并促进了HELF细胞的增殖。
