Fiers W, Brouckaert P, Goldberg A L, Kettelhut I, Suffys P, Tavernier J, Vanhaesebroeck B, Van Roy F
Laboratory of Molecular Biology, State University of Ghent, Belgium.
Ciba Found Symp. 1987;131:109-23. doi: 10.1002/9780470513521.ch8.
We have cloned the cDNAs of both human and mouse TNF and expressed them to high efficiency in Escherichia coli. Many transformed cell lines are sensitive to the cytotoxic action of TNF, especially in the presence of gamma-interferon, whereas normal cells either are unaffected or respond mitogenically. A number of human-mouse chimeric TNF genes have been constructed and expressed. All show biological activity but none of the chimeric proteins is neutralized by monoclonal antibodies to TNF. TNF has potent antitumour activity in nude mice carrying human xenografts or in mice bearing syngeneic tumours. In some systems direct effects can be demonstrated (in combination with species-specific gamma-interferon) but in others TNF acts indirectly. Combination of TNF with cytostatic drugs can also be effective in curing in vivo. The major limitation of the use of TNF is its toxicity. On many cell types TNF has an action similar to interleukin 1 (IL-1). At least some of the secondary, intracellular events may be identical for the two effectors. A possible mechanism of action of TNF is the release and metabolism of polyunsaturated fatty acids, which would explain the synthesis of prostaglandins and leukotrienes by many cell types after TNF treatment. The activation of the phospholipase can be blocked by corticoids. Some protease inhibitors protect cells from TNF-induced cytotoxicity but the target of these inhibitors has not been identified. Several genes are switched on by TNF (and by IL-1), including the gene for the 26 kDa protein recently identified as B cell stimulation factor 2. Events preceding death in rats include hypothermia, hypotension, acidosis and hypoglycaemia. All these effects can be largely eliminated by indomethacin pretreatment, with a resulting improvement in survival. As indomethacin does not inhibit the cytotoxic action of TNF on malignant cells it may form the basis for improved treatment protocols.
我们已经克隆了人类和小鼠肿瘤坏死因子（TNF）的cDNA，并在大肠杆菌中高效表达。许多转化细胞系对TNF的细胞毒性作用敏感，尤其是在γ干扰素存在的情况下，而正常细胞要么不受影响，要么有丝分裂反应。已经构建并表达了一些人-鼠嵌合TNF基因。所有这些都显示出生物活性，但没有一种嵌合蛋白被抗TNF单克隆抗体中和。TNF对携带人异种移植物的裸鼠或携带同基因肿瘤的小鼠具有强大的抗肿瘤活性。在某些系统中可以证明直接作用（与物种特异性γ干扰素联合使用），但在其他系统中TNF起间接作用。TNF与细胞抑制药物联合使用在体内也可能有效。使用TNF的主要限制是其毒性。在许多细胞类型上，TNF的作用类似于白细胞介素1（IL-1）。至少一些次级细胞内事件可能对这两种效应器是相同的。TNF可能的作用机制是多不饱和脂肪酸的释放和代谢，这可以解释TNF处理后许多细胞类型中前列腺素和白三烯的合成。磷脂酶的激活可以被皮质类固醇阻断。一些蛋白酶抑制剂可以保护细胞免受TNF诱导的细胞毒性，但这些抑制剂的作用靶点尚未确定。TNF（以及IL-1）可开启多个基因，包括最近被鉴定为B细胞刺激因子2的26 kDa蛋白的基因。大鼠死亡前的事件包括体温过低、低血压、酸中毒和低血糖。吲哚美辛预处理可以在很大程度上消除所有这些影响，从而提高生存率。由于吲哚美辛不抑制TNF对恶性细胞的细胞毒性作用，它可能成为改进治疗方案的基础。
