Molecular analysis of the inhibition of interleukin-8 production by dexamethasone in a human fibrosarcoma cell line.
In order to analyse the effects of glucocorticoids on interleukin-8 (IL-8) production more precisely, we examined the effects of dexamethasone on IL-8 production at the molecular level in a human fibrosarcoma cell line, 8387, which IL-1 induces to express IL-8 messenger RNA (mRNA) and to secrete IL-8. Over a wide dose range, dexamethasone inhibited IL-8 production induced by IL-1 alpha stimulation. Northern blotting analysis showed that dexamethasone also inhibited the IL-8 mRNA accumulation in a similar dose-related manner. Nuclear run-off assay revealed that dexamethasone decreased the transcription of the IL-8 gene and the degree of inhibition of transcription correlated well with the inhibition of IL-8 production, suggesting that the action of glucocorticoids is mainly at the transcriptional level. Furthermore, transfection with chloramphenicol acetyl transferase (CAT) expression vectors inserted with the 5'-deleted IL-8 gene demonstrated that the 5'-flanking region which contains the glucocorticoid response element (GRE) was mainly involved in the dexamethasone-induced repression of the IL-8 gene. These data suggest that the inhibition of the IL-8 gene transcription by glucocorticoids occurs through the interaction of the glucocorticoid receptor complex with GRE in the 5'-flanking region of the IL-8 gene.
Mukaida
N
N
Department of Clinical Pathology, Jichi Medical School, Minami-kawachi-machi, Japan.
Gussella
G L
GL
Kasahara
T
T
Ko
Y
Y
Zachariae
C O
CO
Kawai
T
T
Matsushima
K
K
D015152:Blotting, Northern; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D005354:Fibrosarcoma / Q000235:genetics / Q000276:immunology; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured / Q000276:immunology
D016209:Interleukin-8; D012333:RNA, Messenger; D003907:Dexamethasone