真核表达载体介导白细胞介素24在HepG2细胞的表达及其体外抗肿瘤效应研究

目的  研究真核表达载体pcDNA3.1(+) 介导白细胞介素（interleukin, IL）24在肝癌细胞系HepG2细胞中表达的可行性，以及IL-24体外对HepG2细胞的抗瘤效应和可能机制。方法 采用脂质体转染法将重组质粒pcDNA3.1(+)-IL-24 及空质粒分组转染HepG2细胞，在倒置显微镜下观察细胞形态变化。用噻唑蓝比色方法测量细胞增殖指数，流式细胞仪研究细胞早期凋亡率及其细胞周期分布。结果  IL-24 mRNA成功表达于HepG2细胞中。重组质粒转染组可见明显的凋亡细胞形态，48 h增殖抑制率（F=27.058，P<0.01）、72 h增殖抑制率( F=63.481，P<0.01)和早期细胞凋亡率( F=326.220，P<0.01)与对照组的差异均有统计学意义。细胞分布呈明显的G2/M周期阻滞。结论 真核表达载体pcDNA3.1(+)可以有效地介导IL-24在HepG2细胞的表达。IL-24对HepG2细胞有明显的增殖阻滞和凋亡诱导效应，G2/M细胞周期阻滞或许是IL-24抗瘤效应的机制。  

Expression of interleukin (IL)-24 in hepatocellular carcinoma cell line HepG2 mediated by eukaryotic vector and the anti-tumor effect of IL-24 in vitro

Objective  To study the feasibility of a eukaryotic vector mediating expression of MDA-7/IL-24 in hepatocellular carcinoma cell line HepG2, the anti-tumor effect of MDA-7/IL-24 in HepG2 cells and possible working mechanism for the tumor-suppressor activity.   Methods   The recombinant plasmid pcDNA3.1(+)-IL-24 and empty plasmid pcDNA3.1(+) were transfected into HepG2 cells by liposome transfection, respectively. Morphological changes of apoptosis were observed under inverted microscope. The proliferation-inhibiting effect of IL-24 in HepG2 cells was observed with Thiazolyl blue assay. Apoptosis ratio and cell-cycle were analyzed by flow cytometry.   Results  The mRNA of IL-24 was detected in HepG2 cells transfected with pcDNA3.1(+)- IL-24 successfully. The typically morphological changes of apoptotis of cells transfected with the target gene were observed obviously. The proliferation-inhibiting rates at 48 h post-transfection (F=27.058, P<0.01), and 72 h post-transfection (F=63.481, P<0.01), and apoptosis indexes (F=326.220，P<0.01) in IL-24 group were significantly higher than those in control groups, with the proportion of cells in the phase of G2/M in IL-24 group being higher, too.   Conclusions   The recombinant eukaryotic vector pcDNA3.1(+) can mediate expression of MDA-7/ IL-24 in HepG2 cells effectively. IL-24 displays growth-inhibiting and apoptosis-inducing activity in HepG2 cells and cell circle arrest in the phase of G2/M  may be the working mechanism of the anti-tumor effect.