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

人类恶性胶质瘤是发生在大脑中最可怕的肿瘤之一，患者的平均生存时间不到两年。由于恶性胶质瘤侵袭到正常脑组织，并倾向于通过脑脊液扩散到蛛网膜下腔，手术切除和/或放射治疗不可能成功。要治愈患有恶性脑瘤的患者，需要靶向治疗，这种治疗可以选择性地杀死肿瘤细胞，而不会对正常细胞造成任何损害。为此，我们一直在利用脂质体和单抗(MCA)研究细胞毒剂对胶质瘤细胞的靶向性。我们将Hu干扰素-Betza基因插入真核表达载体(pSV2IFN-beta)中，并将其导入表面带正电荷的新型脂质体中，发现脂质体介导的基因转移导致细胞产生Hu干扰素-β，进而抑制细胞生长。当含质粒脂质体与抗胶质瘤表面抗原的MCA G-22偶联时，细胞内HuIFN-β的产生增加，并完全抑制胶质瘤细胞的生长。体外实验发现，经肿瘤坏死因子-α(TNF-α)处理后，转染人干扰素-β基因的细胞产生的干扰素-β在转染组细胞中明显增加，且在转染组9天后细胞完全消失。如果在基因导入前给予肿瘤坏死因子-α，裸鼠皮下移植的人脑胶质瘤可以被完全杀死。因此，脑瘤基因治疗的大门已经打开。

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.