Parathyroid hormone (1-34)-mediated interleukin-6 induction.
Parathyroid hormone (PTH) functions in part by regulating osteoblast cytokine expression. We recently demonstrated that PTH induced a rapid and transient increase in interleukin-6 (IL-6) mRNA expression in rat bones in vivo. To determine the molecular basis of this effect, we analyzed the human IL-6 promoter fused (-1,179 to +9) with the chloramphenicol acetyltransferase (CAT) reporter gene in stable transfections into human osteoblast-like osteosarcoma SaOS-2 cells. We compared the effects of PTH on IL-6 expression with adenylate cyclase activator forskolin, PKC activator phorbol 12-myristate 13-acetate (PMA), calcium ionophore A23187, interleukin-1 alpha (IL-1 alpha), prostaglandin E-2 (PGE-2), RS-66271 (a parathyroid hormone-related peptide analog), and platelet-derived growth factor-BB (PDGF-BB). Analyses of cell clones showed that IL-6 promoter expression was extremely low in the unstimulated state. Exposure to PTH (0.001-100 nM) for 12 h stimulated CAT expression in a dose-dependent manner (200-500% of control). Treatment with IL-1 alpha was more potent than PTH in inducing transcription of the IL-6 promoter (900-1,000%). Activation of the cAMP-PKA pathway by treatment with forskolin induced a comparable level of induction with PTH. Together, the effects of PTH and forskolin were additive. RS-66271, previously shown to have PTH-like effects, induced a comparable level of IL-6 promoter expression. When examined together, PTH+RS-66271 effects were comparable to PTH effects alone. Exposure to PGE-2, PMA, PDGF-BB, or A23187 for 12 h did not significantly alter IL-6 promoter expression. These results demonstrate PTH, forskolin, the PTHrP analog RS-66271, and IL-1 alpha stimulate IL-6 expression by stimulating gene transcription. The response to forskolin suggests that the messenger system mediated by PKA is sufficient to induce IL-6 expression.
Onyia
J E
JE
Endocrine Division, Lilly Research Labs, Indianapolis, Indiana 46285, USA.
Libermann
T A
TA
Bidwell
J
J
Arnold
D
D
Tu
Y
Y
McClelland
P
P
Hock
J M
JM
D000077214:Becaplermin; D000001:Calcimycin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004347:Drug Interactions; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D012516:Osteosarcoma; D010957:Plasmids; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D020574:Proto-Oncogene Proteins c-sis; D011993:Recombinant Fusion Proteins; D019379:Teriparatide / Q000031:analogs & derivatives / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured
D007375:Interleukin-1; D015850:Interleukin-6; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011993:Recombinant Fusion Proteins; D019379:Teriparatide; D000077214:Becaplermin; D005576:Colforsin; D000001:Calcimycin; C104917:RS 66271; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate