Bethea J R, Chung I Y, Sparacio S M, Gillespie G Y, Benveniste E N
Department of Neurology, University of Alabama, Birmingham 35294.
J Neuroimmunol. 1992 Feb;36(2-3):179-91. doi: 10.1016/0165-5728(92)90049-q.
Cells that produce tumor necrosis factor-alpha (TNF-alpha) require the presence of signaling molecules since this cytokine is not normally expressed in a constitutive manner. It has been demonstrated that glial cells can produce TNF-alpha; however, the specific inducing molecules and their mechanism(s) of action have not been clearly defined. In this study, we examined the effect of human recombinant interleukin-1 beta (IL-1 beta) on the expression of TNF-alpha by CH235-MG human malignant glioma cells. CH235-MG cells do not constitutively express TNF-alpha mRNA or protein; however, upon stimulation with IL-1 beta, these cells synthesize and secrete biologically active TNF-alpha. IL-1 beta induces the expression of a 1.9 kb TNF-alpha mRNA species. Kinetic analysis demonstrated optimum TNF-alpha mRNA expression after a 4 h exposure to IL-1 beta, and peak TNF-alpha protein production at 18 h. Cycloheximide (CHX), an inhibitor of protein synthesis, markedly increased expression of TNF-alpha mRNA in IL-1 beta stimulated CH235-MG cells, indicating that de novo protein synthesis is not required for astroglioma TNF-alpha gene expression. Nuclear run-off analysis demonstrates that IL-1 beta causes transcriptional activation of the TNF-alpha gene, and CHX enhances IL-1 beta-induced TNF-alpha transcription. Studies of TNF-alpha mRNA stability using actinomycin D show that IL-1 beta-induced TNF-alpha mRNA has a half-life of approximately 30 min, and CHX increases the half-life of IL-1 beta-induced TNF-alpha mRNA to approximately 210 min. These results indicate that IL-1 beta, a cytokine present in the central nervous system during some pathological disease states, is a potent inducer of TNF-alpha in human malignant glioma cells.
产生肿瘤坏死因子-α（TNF-α）的细胞需要信号分子的存在，因为这种细胞因子通常不是以组成型方式表达的。已经证明神经胶质细胞可以产生TNF-α；然而，具体的诱导分子及其作用机制尚未明确界定。在本研究中，我们检测了人重组白细胞介素-1β（IL-1β）对CH235-MG人恶性胶质瘤细胞TNF-α表达的影响。CH235-MG细胞不组成型表达TNF-α mRNA或蛋白质；然而，在用IL-1β刺激后，这些细胞合成并分泌具有生物活性的TNF-α。IL-1β诱导一种1.9 kb的TNF-α mRNA种类的表达。动力学分析表明，在暴露于IL-1β 4小时后TNF-α mRNA表达达到最佳，在18小时时TNF-α蛋白质产生达到峰值。蛋白质合成抑制剂放线菌酮（CHX）显著增加了IL-1β刺激的CH235-MG细胞中TNF-α mRNA的表达，表明星形胶质瘤TNF-α基因表达不需要从头合成蛋白质。核转录分析表明，IL-1β导致TNF-α基因的转录激活，并且CHX增强IL-1β诱导的TNF-α转录。使用放线菌素D对TNF-α mRNA稳定性的研究表明，IL-1β诱导的TNF-α mRNA半衰期约为30分钟，而CHX将IL-1β诱导的TNF-α mRNA半衰期增加到约210分钟。这些结果表明，IL-1β是在某些病理疾病状态下存在于中枢神经系统中的一种细胞因子，是人类恶性胶质瘤细胞中TNF-α的有效诱导剂。
