肿瘤细胞靶向性白细胞介素4(IL-4)融合蛋白的研究

白细胞介素 4受体 (IL-4R)特异地存在于多种肿瘤细胞表面 ,这为某些肿瘤的治疗提供了一个靶向标记。在以前的研究中 ,人白细胞介素-4(Hil-4)与白喉毒素 (DT)的融合蛋白 (DT4H)被构建 ,且它对某些肿瘤细胞系的高毒性得到了证明。但是 ,由于毒素部分的强免疫原性 ,它可以诱导人体的免疫反应。该研究中我们构建了白细胞介素 4与绿脓杆菌外毒素 (PE) 253～608aa的融合蛋白 ,并在其N端添加了 6×His标记方便纯化 ,在其C端添加了KDEL提高毒性。为了改善与IL-4R的亲和力我们将IL-4进行了环式重组 ,构建的融合毒素 ,H404K ,经DEAE$CSepharoseFastFlow及Ni-NTA纯化后 ,纯度达 90 %。纯化后的H404K与DT4H相似 ,对U251高度敏感 ,对MCF7及HepG2中度敏感 ,且我们首次证实该毒性不会被兔抗白喉毒素的多克隆抗体所抑制。这些研究表明 ,H404K与DT4H可以以一种互为替代的方式用于某些恶性肿瘤的治疗

Fusion Protein of Interleukin 4 and Pseudomonas Exotoxin with High Cytotoxicity to Cancer Cells

Receptors of human interleukin 4 (hIL4R) have been found to be present on many types of cancers, so they could be good targets for cancer therapy. Previously, a fusion protein (DT4H) was constructed with human interleukin 4 (hIL4) and diphtherial toxin (DT). Although it is high cytotoxic to several cancer cell lines, human immune response to it would be expected in future clinical trials. Here another fusion toxin was constructed by fusing hIL4 to DNA sequence encoding the 253-608 amino acids of Pseudomonas exotoxin (PE). The fusion gene was expressed in Escherichia coli which results in a large amount of the fusion toxin (H404K). Purified H404K was very cytotoxic to cancer cell line U251 and moderate cytotoxic to HepG2 and MCF-7, which is similar to DT4H. Furthermore,for the first time we show that its cytotoxicity can not be inhibited by rabbit anti-DT polyclonal antibody. These results suggest that H404K would be expected to have good therapeutic value as an alternative therapy of DT4H in the treatment of some malignancies.