人sTRAIL基因的克隆、表达纯化及对人A549细胞的抗肿瘤活性作用

目的人TRAIL基因胞外区片段(114-281氨基酸残基,sTRAIL)的克隆、表达、纯化及对人肺腺癌A549细胞的抗肿瘤活性研究。方法采用PCR技术从人胎盘和肺cD-NA文库中扩增出全长人TRAIL基因,克隆到pUC19质粒载体上进行测序。然后再采用PCR技术,以全长人TRAIL基因为模板,扩增出sTRAIL基因片段并定向克隆到pET-11 a表达载体中,转化大肠杆菌BL21进行表达。表达后的产物经变性、复性和分离纯化,纯化后的sTRAIL用结晶紫染色法和流式细胞仪法测定其对人肺癌细胞A549的细胞毒性作用。结果从人胎盘和肺cDNA文库中都能扩增出全长人TRAIL基因,经测序表明与已发表的人TRAIL基因序列一致。扩增出的人sTRAIL基因克隆到表达质粒载体pET-11a,经IPTG诱导表达,表达量占细菌全菌蛋白的50%,纯化后的sTRAIL纯度大于98%,结晶紫法测定对人A549肺癌细胞的细胞毒性作用的IC50为(24±5.2)μg.L-1,流式细胞仪法测定对人A549肺癌细胞的细胞毒性具有明显的效应-时间依赖关系。结论本实验成功地克隆了人sTRAIL基因并实现其高表达,摸索出包涵体sTRAIL的变性、复性及其纯化方法,纯化后的sTRAIL蛋白对人A549肺癌细胞具有明显的细胞毒性作用,为进一步研究其功能与临床应用奠定了基础。

Cloning expression purification and cytotoxic assay of sTRAIL in A549 cell line

Aim To clone,express sTRAIL gene,then purify sTRAIL(114-281 amino acid) and assay its cytotoxic activity in human A549 cell line.Methods The intact full human TRAIL gene was amplified using PCR method from the human placenta and lung cDNA library.The full human TRAIL cDNA gene was inserted into pUC19 vector and sequenced.The extracellular DNA fragment was amplified using PCR,which was cloned to pET-11a vector and transformed into E.coli BL21.The denatured and refolded sTRAIL was purified and cytotoxic activity of sTRAIL was assayed using crystal violet staining and fluorescence-activated cell sort(FACS) in A549 cell line.Results The full length TRAIL cDNA gene was amplified from the human placenta and lung cDNA library,which was identical to the published TRAIL sequence.The extracellular DNA fragment was cloned to pET-11a.The expression level reached 50% of the total protein of BL21.The purity of sTRAIL was about 98%,while IC_(50) was about(24±5.2) μg·L~(1) in TRAIL-treated A549 cells with crystal violet staining method.The time-dependent relationship of sTRAIL-induced apoptotic death in A549 cells was significant with FASC analysis.Conclusion sTRAIL gene has been cloned and successfully expressed.The process of refolding and purification of sTRAIL has been established.sTRAIL demonstrated cytotoxicity in A549 cell line.