小干扰RNA抑制MG-63细胞cyclin A2基因的表达

Knockdown of cyclin A2 expression by small interfering RNA in MG-63 cells

目的利用小干扰RNA(siRNA)抑制骨肉瘤及正常成纤维细胞中cyclin A2基因的表达,并观察其对细胞生物活性的影响。方法设计并化学合成3对针对cyclin A2基因的siRNA,用Oligofectamine分别将其转染到骨肉瘤细胞系MG-63及正常人成纤维细胞HSF中,以无义siRNA转染作为阴性对照;以real-time PCR、Western blot检测cyclin A2基因沉默效果,采用MTT、RT-PCR、流式细胞、克隆培养等方法评价抑制cyclin A2基因表达后细胞的生长状态,同时检测PCNA及cyclin B1表达的改变。结果3对siRNA均能使cyclin A2 mRNA的表达降低,其中siRNA,抑制率最高。在骨肉瘤细胞MG-63中,转染50 nmol/L的siRNA,48 h后,cyclin A2的mRNA及蛋白表达被抑制近80%,这导致细胞增殖抑制,80.1%的细胞被阻滞在G0/G1期,克隆形成能力下降至45.5%,同时,PCNA及cyclin B1的mRNA表达明显降低。对正常成纤维细胞HSF,虽然siRNA1能抑制近60%的cyclin A2 mRNA及蛋白表达,但细胞的增殖及克隆形成能力未受影响。结论针对cyclin A2基因的siRNA能有效降低细胞中cyclin A2 mRNA及蛋白的表达,抑制骨肉瘤细胞的生长,而对正常细胞影响不大。表明cyclin A2是骨肉瘤细胞增殖所依赖的关键基因,抑制其表达有望成为治疗骨肉瘤的新途径。

Objective To study the inhibitory effect of small interference RNA （siRNA） targeting cyclin A2 gene on the growth of osteosarcoma MG-63 and human normal skin fibroblast HSF cells and to explore whether cyclin A2 siRNAs could become a useful tool in the treatment of osteosareoma. Methods Three pairs of siRNAs targeting cyclin A2 mRNA and a pair of nonsense siRNA were designed according to the current criteria. SiRNAs were chemically synthesized and purified. The siRNAs were transfected into MG-63 cells and HSF cells via oligofectamine. The cells transfected with nonsense siRNA served as negative control group and those only treated with PBS as blank control group. Quantitative fluorescence RT-PCR, Westernblot, MTr assay, reverse transcriptase（RT）-PCR, flow cytometry and clone forming test were employed to evaluate the efficacy of RNA interference. At the same time, the mRNA expression of PCNA and cyclin B1 in siRNA-treated MG-63 cells were examined. Results Although all three siRNAs could reduce the cyclin A2 expression, siRNA1 appeared to be the most effective. After 48 h treatment with siRNA1, cyclin A2 mRNA and protein expression in MG-63 cells was significantly reduced by nearly 80% as compared with that of the blank control group, whereas the negative and blank control groups had similar expression levels. MG- 63 cells treated with siRNA1 were arrested at G0/G1 phase by 80. 1% and the proliferation of these tumor cells was suppressed 48 h after transfection. Furthermore, MG-63 cells showed a decreased colony forming ability after siRNA1 treatment. In addition, the cyclin A2-depleted MG-63 cells showed decreased levels of PCNA and cyclin B1. In contrast, although cyclin A2 expression in HSF reduced by nearly 60% after treatment by siRNA1 for 48h, these cells exhibited only a slight change in cell cycling, and neither clear inhibition of proliferation nor impaired colony forming ability was observed. Conclusion cyclin A2 is critical for proliferation of MG-63 cells, cyclin A2-siRNAs can induce obvious inhibition of cyclin A2 mRNA and protein expression in MG-63 and HSF cells, which consequently down-regnlate the proliferation of MG- 63 cells. There is little effect on the proliferation of siRNA-treated HSF cells. Those results indicate that siRNAs against cyclin A2 may become a potential antiproliferative tool in future antitumor therapy.