野生型INK4a/ARF基因共转染对A549细胞生物学行为的影响

Effects of wild-type INK4a/ARF gene on biological behavior of lung adenocarcinoma cell line A549

背景与目的INK4a/ARF基因是重要的细胞周期调控基因,其表达产物p16INK4a和p14ARF蛋白分别在Rb和p53通路中发挥重要调节作用。本研究将野生型INK4a/ARF基因同时转染到该基因位点缺失的人肺腺癌A549细胞中,研究其对该细胞生物学行为的影响。方法利用阳离子脂质体介导的基因转染技术,将含有人全长野生型INK4a/ARF基因的真核表达重组质粒pcDNA3p16INK4a和pcDNA3p14ARF同时导入A549细胞系中,确定所编码蛋白p16INK4a和p14ARF稳定表达;在设立空白组和空质粒转染组的情况下,进行了转染前后细胞生长曲线、克隆形成率、周期分布、凋亡指数等指标的检测和分析。结果转染INK4a/ARF基因后的细胞G0/G1期比例为59.9%,与未转染(51.2%)及空质粒转染(50.3%)细胞相比差异显著(P值分别为0.043和0.025),同时S期和G2/M期的比例下降;转染后细胞克隆形成率为63%,未转染细胞和空质粒转染细胞分别为85%和87%(P值均<0.01),凋亡指数明显增加,转染INK4a/ARF基因后的细胞凋亡率为8.0%,另两种细胞均为2.7%,差异具有统计学意义(P<0.01)。结论阳离子脂质体可以有效地将INK4a/ARF基因导入A549细胞,并可以抑制A549细胞的生长,促进凋亡作用的增强,为将来肺癌的基因治疗提供了实验依据。

Background and objective p16INK4a and p14ARF, encoded by gene INK4a/ARF located at chromosome 9p21, are cyclin dependent kinase （CDK） inhibitors. Both p16INK4a and p14ARF are cell cycle regulatory proteins and play an important role in Rb and p53 passways respectively. In this study, wild-type INK4a/ARF gene was transfected into human lung adenocarcinoma cell line A549, in which this gene site was lost, and the effects on the cell＇s biological behavior were investigated. Methods The recombinant eukaryotic expression plasmids pcDNA3-p16INK4a and pcDNA3-p14ARF were transfected into A549 by cationic liposome method. By RT-PCR, immunocytochemistry and Western blot after G418 selection, A549 cells that could stably express p16INK4a and p14ARF were obtained. As a control, the parental cell and negative control cell with plasmid pcDNA3-LacZ were used. Inhibition of proliferation was measured by MTT assay. The cell growth curve was drawn according to cell counts. Cell cycle distribution was measured by flow cytometry （FCM）, the apoptosis indexes were observed at the same time. The colony formation rate was counted by staining the cells with Coomassie brilliant blue. Results The introduction of exogenous INK4a and ARF caused significantly growth inhibition of A549. By FCM, more percentage of A549-p16INK4a-p14ARF cells couldn＇t pass through the checkpoint G1. The percentage of A549-p16INK4a-p14ARF cells inhibited at G0/G1 was 59.9%, 50.3% for A549-vector and 51.2% for A549. The statistical differences were significant between A549-p16INK4a-p14ARF cell and A549-vector cell （P=0. 025） and between A549-p1GINK4a-p14ARF cell and A549 cell （P=0. 043）. The apoptosis index of A549-p16INK4a-p14ARF cell was 8.0% and 2.7% for both A549-vector and A549 cell （P〈0.01）. The colony formation ability of A549-p16INK4a-p14ARF was weaker than that of A549-vector and A549, they were 63%, 87% and 85% respectively. Conclusion The wild-type INK4a/ARF gene can be co-introduced effectively into A549 cell by cationic liposome method. The reexpression of p16INK4a and p14ARF in A549 can inhibit the growth and enhance the apoptosis. This trial will be helpful in using gene therapy of lung cancer in the future.