关键词: p53, 细胞周期, cyclin A, Cdk4

Abstract: BACKGROUND ＆ AIM: We investigated the role of wild type and H179Y_mutated p53 in the regulation of HELF cell cycle and proliferation. MATERIALS AND METHODS: We transfected pcDNA3_wild_type p53 (pcDNA3_wtp53) and pcDNA3_H179Y_mutated p53 (pcDNA3_mtp53) plasmids into human embryonic lung fibroblast (HELF) cells. Then we analyzed cell proliferation by cell growth assays, analyzed cell cycle by flow cytometry, and detected the expression levels of mRNA and proteins by PCR and Western blotting. RESULTS: 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 A and Cdk4 expression. CONCLUSION: These results indicated that mutation at the p53 H179Y residue caused up_regulation in the expression of cyclin A and Cdk4, promoting HELF cell proliferation.

Key words: p53, cell cycle, cyclin A, Cdk4