抗前列腺癌/抗CD3双特异性单链抗体的构建及表达

Construction and expression of anti-CD3/anti-prostate-cancer bispecific single-chain antibody

目的 构建并表达抗前列腺癌 /抗人CD 3双特异性单链抗体 ,观察其生物学活性及临床意义。方法 利用PCR方法及分子生物学基因克隆技术 ,构建抗前列腺癌 /抗人CD 3双特异性单链抗体融合基因 ,测序正确后 ,利用EcoRI和HindⅢ酶切位点 ,将融合基因亚克隆入真核表达载体进行表达 ,表达产物纯化后 ,利用流式细胞仪进行生物学活性测定。结果 经酶切、测序分析证实插入的基因片段大小为 1 5kb ,序列与设计完全一致 ;SDS PAGE和Western印迹实验证明 :表达产物分泌于细胞培养上清 ,相对分子质量为 6 10 0 0 ;流式细胞仪结果显示 :双特异性单链抗体与PBMC和PC 3细胞的阳性结合率分别为 5 4 1%和 5 3 7%。结论 抗前列腺癌 /抗人CD 3双特异性单链抗体具有较好的生物学活性 ,为进一步的体内实验奠定了基础。

Objective To construct a recombinant vector that expresses anti-CD 3/anti-prostate-cancer bispecific single-chain antibody (BsAb), and study its biological activities and clinical significance. Methods An anti-CD 3/anti- prostate-cancer BsAb was constructed by PCR and molecular biological technique of DNA cloning. The fusion gene, confirmed by sequencing, was subcloned into the pSectag2-B plasmid from the pUC18 vector by digestion with EcoR I and Hind Ⅲ restriction endonucleases, whose sites exist in both the vectors. Then the recombinant plasmid was transfected into HeLa cells. The expression products in the supernatant were analyzed by both SDS-PAGE and Western blot technique, then were purified with Ni 2+ -NTA superflow affinity chromatography. Its biological activities were examined by flow cytometry (FCM). Results A fragment of 1.5kb was inserted into the pUC18 vector, which was sequenced and verified to be identical with that designed. The expression of anti-CD 3×anti-prostate-cancer BsAb yielded a soluble protein with an apparent molecular mass of 61 KD. The purification rate of the expressed BsAb was up to 90.537% and the yield of purified BsAb from this procedure was 0.09 mg/ml. The positive binding rates of BsAb to PBMC and to PC-3 cell were 54.1% and 53.7% respectively. Conclusion The anti-CD 3×anti-prostate-cancer BsAb thus constructed exhibits beneficial biological activities and may play an important role in the treatment of prostate cancer.