cAMP-induced astrocytic differentiation of C6 glioma cells is mediated by autocrine interleukin-6.
Elevation in the level of intracellular cAMP is known to induce the astrocytic differentiation of C6 glioma cells by unknown mechanisms. In this report, we show that cAMP-induced autocrine interleukin 6 (IL-6) promoted astrocytic differentiation of C6 cells. Treatment of cells with N(6),2'-O-dibutyryl cAMP (Bt(2)AMP) and theophylline caused the delayed phosphorylation of signal transducer and activator of transcription 3 (STAT3), as well as the expression of an astrocyte marker, glial fibrillary acidic protein (GFAP). Overexpression of the dominant-negative form of STAT3 leads to the suppression of GFAP promoter activity, suggesting that STAT3 activity was essential for cAMP-induced GFAP promoter activation. On the other hand, the IL-6 gene was quickly induced by Bt(2)AMP/theophylline, and subsequent IL-6 protein secretion was stimulated. In addition, recombinant IL-6 induced GFAP expression and STAT3 phosphorylation. Most importantly, treatment with IL-6-neutralizing antibody dramatically reduced the cAMP-induced GFAP expression and STAT3 phosphorylation and reversed the cellular morphological changes that had been caused by Bt(2)AMP/theophylline. Taken together, these results indicated that Bt(2)AMP/theophylline lead to delayed STAT3 activation via autocrine IL-6. These processes subsequently led to the induction of GFAP. IL-6 secretion is thus thought to be a key event in controlling the astrocytic differentiation of C6 cells.
Takanaga
Hiromi
H
Department of Public Health and Molecular Toxicology, School of Pharmaceutical Sciences, Kitasato University, Tokyo 108-8641, Japan.
Yoshitake
Tomoko
T
Hara
Shuntaro
S
Yamasaki
Chieri
C
Kunimoto
Manabu
M
D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism; D003994:Bucladesine / Q000378:metabolism; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D017930:Genes, Reporter; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005910:Glioma / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism / Q000502:physiology*; D007546:Isoquinolines / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor; D013449:Sulfonamides; D013806:Theophylline / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; D015850:Interleukin-6; D007546:Isoquinolines; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D013449:Sulfonamides; D015534:Trans-Activators; D003994:Bucladesine; D013806:Theophylline; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide