Induction of endogenous interferon by superinduction or gene transfection and its anti-tumor activity toward malignant glioma

人类恶性胶质细胞是大脑中最可怕的肿瘤之一，患者的平均生存时间不到两年。由于恶性胶质细胞侵袭正常脑组织，并倾向于通过脑脊液扩散到蛛网膜下腔，手术切除和/或放疗不能指望成功。要治愈恶性脑肿瘤患者，需要有选择性地杀死肿瘤细胞而不损害正常细胞的靶向治疗。为此，我们一直在研究利用脂质体和单克隆抗体（MCA）靶向胶质瘤细胞的细胞毒性药物。我们将HuIFN-betza基因插入真核表达载体（pSV2IFN-beta）中，将其包埋到表面带正电荷的新型脂质体中，发现脂质体介导的HuIFN-beta基因转移到培养的胶质瘤细胞中，细胞内产生HuIFN-beta并抑制其生长。当含有脂质体的质粒与G-22（一种针对胶质瘤相关表面抗原的MCA）偶联时，细胞中huifn - β的产生增加，胶质瘤细胞的生长抑制完成。此外，我们通过体外实验发现，转染该基因的细胞在转染前用肿瘤坏死因子- α (tnf - α)处理可以增加细胞中huifn - β的产生，并且在转染后9天细胞完全消失。人胶质瘤皮下移植裸鼠，在基因转染前给予tnf - α可完全杀死小鼠。因此，基因治疗脑肿瘤的大门已经打开。

Human malignant gliona is one of the most formidable neoplases arising in the brain, and patients afflicted have an average survival time of less than two years. Since malignant gliona invades aggressively into normal brain tissue and tends to disseminate into the subarachnoid space via the cerebro-spinal fluid, surgical resection and/or radiation cannot be expected to be successful. To cure the patient with a malignant brain tumor requires targeting therapy which selectively kills the tumor cells without any damage to normal cells. For this purpose, we have been studying the targeting of cytotoxic agents to glioma cells by using liposomes and a monoclonal antibody(MCA). We entrapped the HuIFN-betza gene inserted in a eukaryotic expression vector (pSV2IFN-beta) into novel liposomes having positive charge on their surface, and found that our liposome-mediated transfer of the gene to cultured glioma cells brought about the production of HuIFN-beta in the cells followed by their growth inhibition. When the plasmid-containing liposomes were coupled with G-22, an MCA against a glioma-associated surface antigen, production of HuIFN-beta in the cells was increased and the growth inhibition of the glioma cells became complete. Furthermore, we found by in vitro experimentation that production of HuIFN-beta in the cells transfected with the gene could be increased by treatment of the cells with tumor necrosis factor-alpha (TNF-alpha) prior to the transfection and that the cells completely disappeared by 9 days after the transfection. Human glioma subcutaneously transplanted into nude mice could be killed completely if the mice were given TNF-alpha prior to the gene transfection. Thus the gate to gene therapy for brain tumors has been opened.