摘要：AIM： To construct and produce a recombinant bispecific humanized single-chain Fv （sFv） /interleukin-2 （IL-2） fusion protein by using mammalian cells. METHODS： The sFv/IL-2 protein was genetically engineered, and transfected to mammalian cells to determine whether the mammalian protein folding machinery can produce and secrete active sFv/IL-2 with high efficiency. RESULTS： The fusion protein was constructed and high efficiently expressed with yields up to 102 ±4.2 mg/L in culture supernatant of the stably transfected 293 cell line. This recombinant fusion protein consisted of humanized variable heavy （VH） and light （VL） domains of monoclonal antibody （mAb） 520C9 directed against the human HER-2/neu （c-erbB2） proto-oncogene product p185, and human IL-2 connected by polypeptide linker. The fusion protein was shown to retain the immunostimulatory activities of IL-2 as measured by IL- 2-dependent cell proliferation and cytotoxicity assays. In addition to its IL-2 activities, this fusion protein also possessed antigen-binding specificity against p185, as determined by indirect ELISA using p185 positive SKOV 3ip1 cells. CONCLUSION： The large-scale preparation of the recombinant humanized sFv antibody/IL-2 fusion protein is performed with 293 cells. The recombinant humanized sFv antibody/IL-2 fusion protein may provide an effective *** targeting therapeutic doses of IL-2 to p185 positive tumors without increasing systemic toxicity or immunogenicity.

摘要：目的 构建同时携带白细胞介素2（IL-2）和NK4基因的真核表达载体（pIRES-IL-2-IRES-NK4）,观察其在防治肿瘤中的潜在应用前景.方法 根据Pubmed上公布的IL-2及NK4 mRNA序列,设计扩增IL-2及NK4 cDNA的特异性引物,以PBV220-IL-2质粒和PCAGGS/hNK4质粒为模板,分别扩增IL-2及NK4基因,并将IL-2及NK4基因分别克隆在真核表达载体pIRES-SEQ的XhoI、MLuI位点和SalI、NotⅠ位点.获得同时携带IL-2和NK4基因的重组真核表达质粒pIRES-IL-2-IRES-NK4.该重组质粒转染肝癌细胞HepG2后,检测目的基因的转染表达及表达产物对HepG2细胞增殖的影响.结果 通过对构建质粒克隆进行测序及酶切,证实携带IL-2和NK4双基因的真核表达质粒pIRES-IL-2-IRES-NK4构建成功.用pIRES-IL-2-IRES-NK4转染HepG2细胞后24 h后在荧光显微镜下可观察到细胞有较强的绿色荧光表达,48 h时荧光更强;逆转录聚合酶链反应结果表明转染pIRES-IL-2-IRES-NK4质粒细胞的IL-2及NK4基因表达明显增强.酶联免疫吸附测定检测结果表明,转染组细胞较对照组细胞培养上清中IL-2及NK4蛋白表达水平明显增强.转染组48 h后的IL-2、NK4蛋白表达水平为2.139、1.956 mg/L,明显高于未转染组的0.492、0.620 mg/L.四甲基偶氮唑盐法结果表明转染真核表达质粒pIRES-IL-2-IRES-NK4的细胞表达上清,有明显抑制肝癌细胞HepG2增殖的活性,且有剂量效应关系.结论 本研究成功构建了同时携带IL-2和NK4基因的重组真核表达质粒pIRES-IL-2-IRES-NK4,该质粒可有效转染肝癌细胞,且转染细胞表达上清有明显抑制肝癌细胞HepG2增殖的活性,提示该重组质粒有潜在防治肿瘤的应用前景.