ABSTRACT
Objective:To investigate the effects of epidermal growth factor (EGF)on cell cycle and cell cycle-related regulatory factors of human esophageal squamous cell carcinoma (ESCC) cell line Eca109.Methods: Serum starved Eca109 cells were treated with 20 ng/ml recombinant human EGF(rhEGF)for 24 h.The cell cycle phase distribution was detected by flow cytometry.The mRNA and protein expression levels of p21CIP1/WAF1(p21) and p27KIP1(p27) were detected by real-time quantitative reverse transcription polymerase chain reaction(qRT-PCR)and Western blot,respectively.Results: The proportions of G1 phase cells in EGF group and control group were ( 54.90 ±0.82 )% and ( 65.94 ±0.74 )%.The mRNA and protein expression levels of p 21 in EGF group was significantly higher ,and p27 was significantly lower than that in control group ( P<0.01 ) .Conclusion: EGF facilitates G1-S phase transition,and promotes the proliferation of Eca 109 cells,which may be associated with the up-regulation of p21 and down-regulation of p27.
ABSTRACT
The effect of cyclin-dependent kinase inhibitors Cip1/Wafl (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 24h 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.