The effect of cyclin-dependent kinase inhibitors Cip1/Waf1(p21) on regulatory expression of survivin transcription in human hepatocellular carcinoma cell HepG2 was observed and the related mechanisms explored.Doxorubicin(DOX) was used to treat HepG2.Eukaryotic vector pEGFP-C2-p21 was transfected into HepG2 by lipofectamine and positive clones were screened out by G418.The mRNA expression of p21 and survivin was detected by real-time fluorescent quantitative polymerase chain reaction(RQ-PCR).Flow cytometry was used to examine the cell cycle,and reverse transcription polymerase chain reaction(RT-PCR) was used to measure the levels of E2F-1 and p300.The results showed that:(1) After treatment with DOX,the expression of p21 was increased,whereas that of survivin was reduced during 24 h of treatment;(2) After transfection of pEGFP-C2-p21 into HepG2,p21 level was significantly enhanced to 2100.11-folds or 980.89-folds in comparison to HepG2 or HepG2-C2 group,and survivin level was markedly down-regulated to 0.54% or 0.59% relative to the control groups;(3) Overexpressed p21 resulted in G1/G0 phase arrest(F=31.59,P<0.01),meanwhile E2F-1 mRNA and p300 mRNA were reduced as compared with those of controls(FE2F-1=125.28,P<0.05;Fp300= 46.01,P<0.01).It was suggested that p21 could be a potential mediator of survivin suppression at transcription level in HepG2 cell,which might be through the block at G1/G0 phase and down-regulation of transcription factors E2F-1 and p300.
