title: Interleukin-1beta upregulates MMP-9 expression in stromal cells of human giant cell tumor of bone.
abstract: Giant cell tumor (GCT) of bone is a progressive, potentially malignant process that destroys skeletal tissue. It consists of multinucleated giant cells, which are hypothesized to be derived from a monocyte/macrophage lineage and mononuclear stromal cells, and the precise relationship of these cells is not fully understood. Recently, we demonstrated that the production of matrix metalloproteinase-9 (MMP-9) in GCT stromal cells is regulated by certain factor(s) secreted by the multinucleated giant cells. In the present study, we evaluated for the presence of interleukin-1beta (IL-1beta) and attempted to establish its possible role for the induction of MMP-9 in GCT stromal cells. Using enzyme-linked immunosorbent assay (ELISA), we have demonstrated that the primary GCT cultures secrete both IL-1beta and MMP-9. The addition of monoclonal antibody (mAb) against IL-1beta partially abrogated, but did not abolish, MMP-9 expression. Our results on gelatin zymography, reverse transcriptase-polymerase chain reaction (RT-PCR), and immunofluorescence showed that GCT stromal cells did not express MMP-9, although treatment with IL-1beta induced MMP-9 expression in a dose-dependent manner, and the secretion peaked 24 h after stimulation and then plateaued. Studies with cycloheximide, a protein synthesis inhibitor, demonstrated that de novo protein synthesis is required for IL-1beta induced MMP-9 expression. Moreover, nuclear run-on analysis has revealed that IL-1beta significantly increased MMP-9 gene transcription in GCT stromal cells. The data suggest that IL-1beta secreted by the multinucleated giant cells in GCT may be one of the factors responsible for the induction of MMP-9 at the transcriptional level in GCT stromal cells in vivo. We conclude that GCT has a self-stimulatory system for the production of MMP-9, and the ability of stromal cells to produce MMP-9 with appropriate stimuli, such as IL-1beta, and possibly in concert with other cytokines may contribute to the aggressive and potentially malignant behavior of GCT.
authors.affiliation: Center for Human Molecular Genetics, Munroe Meyer Institute for Genetics and Rehabilitation, and the Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha 68198, USA. vrao@unmc.edu
authors.forename: V H
authors.initials: VH
authors.lastname: Rao
authors.forename: R K
authors.initials: RK
authors.lastname: Singh
authors.forename: D C
authors.initials: DC
authors.lastname: Delimont
authors.forename: G B
authors.initials: GB
authors.lastname: Schaefer
authors.forename: J A
authors.initials: JA
authors.lastname: Bridge
authors.forename: J R
authors.initials: JR
authors.lastname: Neff
authors.forename: W G
authors.initials: WG
authors.lastname: Sanger
authors.forename: J W
authors.initials: JW
authors.lastname: Sappenfield
authors.forename: B A
authors.initials: BA
authors.lastname: Buehler
authors.forename: R H
authors.initials: RH
authors.lastname: Finnell
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D018212:Giant Cell Tumor of Bone / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D007375:Interleukin-1; D020780:Matrix Metalloproteinase 9