title: The regulation of PGE(2) biosynthesis in MG-63 osteosarcoma cells by IL-1 and FGF is cell density-dependent.
abstract: We investigated the molecular mechanisms by which treatment of the human osteoblast-like cell line MG-63 with interleukin 1beta (IL-1) and/or fibroblast growth factor 1 (FGF-1) elicited prostaglandin biosynthesis. IL-1 induced a 5-fold increase in PGE(2) production compared to controls. While treatment with FGF-1 alone did not affect PGE(2) biosynthesis, it enhanced the formation of PGE(2) by IL-1 by an additional 3- to 5-fold. IL-1-induced PGE(2) biosynthesis accompanied increases in steady-state levels of mRNAs encoding cPLA(2) (10- to 15-fold) and PGHS-2 (>3-fold) and concomitant increases in cPLA(2) protein (>3-fold) and PGHS-2 protein (>1. 5-fold). FGF-1 treatment did not affect PGHS-2 gene expression, but enhanced the effect of IL-1 on PGHS-2 expression by an additional 2- to 3-fold. FGF-1 alone enhanced cPLA(2) expression (5-fold), and the combined effects of FGF-1 and IL-1 on cPLA(2) expression were additive. There was no measurable effect of either agonist on PGHS-1 expression. We also discovered that induction of PGE(2) biosynthesis in response to IL-1 or IL-1/FGF-1 was affected by the density of MG-63 cells in culture. Subconfluent cultures displayed a 3- to 10-fold greater response to IL-1 or IL-1/FGF-1 than confluent cultures. The decreased PGE(2) induction by IL-1 in confluent cultures was associated with reduced IL-1 receptor expression. We conclude that the signaling pathways resulting in PGE(2) biosynthesis in response to proinflammatory agents like IL-1 are subject to complex regulation by additional soluble mediators as well as cell-cell or cell-extracellular matrix interactions.
authors.affiliation: Department of Veterans Affairs Medical Center, The University of Tennessee, Memphis, Tennessee 38163, USA. slauderkin@utmem.edu
authors.forename: S J
authors.initials: SJ
authors.lastname: Laulederkind
authors.forename: K
authors.initials: K
authors.lastname: Kirtikara
authors.forename: R
authors.initials: R
authors.lastname: Raghow
authors.forename: L R
authors.initials: LR
authors.lastname: Ballou
mesh_terms: D000818:Animals; D002417:Cattle; D002452:Cell Count; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D016220:Fibroblast Growth Factor 1; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism* / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins; D012516:Osteosarcoma; D010741:Phospholipases A / Q000096:biosynthesis / Q000235:genetics; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger; D011817:Rabbits; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D051496:Receptor, Fibroblast Growth Factor, Type 1; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D017472:Receptors, Interleukin-1 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C496348:FGFR1 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D010741:Phospholipases A; D015232:Dinoprostone