Interleukin-1 beta induction of tumor necrosis factor-alpha gene expression in human astroglioma cells.
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.
Bethea
J R
JR
Department of Neurology, University of Alabama, Birmingham 35294.
Chung
I Y
IY
Sparacio
S M
SM
Gillespie
G Y
GY
Benveniste
E N
EN
D001254:Astrocytoma / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide