|Title:||Osteoblast-Derived Tgf-Beta 1 Stimulates Il-8 Release through Ap-1 and Nf -Kappa B in Human Cancer Cells||Authors:||FONG, YI-CHIN
TSAI, FUU- JEN
|Keywords:||osteoblasts;interleukin-8;TGF-beta 1;NF-kappa B;activator protein 1||Issue Date:||2008||Journal Volume:||v.23||Journal Issue:||n.6||Start page/Pages:||961-970||Source:||JOURNAL OF BONE AND MINERAL RESEARCH||Abstract:||
Introduction: The bone marrow microenvironment is further enriched by growth factors released during osteoclastic bone resorption. It has been reported that the chemokine interleukin (IL)-8 is a potent and direct activator of osteoclastic differentiation and bone resorption. However, the effect of bone-derived growth factors on the IL-8 production in human cancer cells and the promotion of osteoclastogenesis are largely unknown. The aim of this study was to investigate whether osteoblast-derived TGF- beta 1 is associated with osteolytic bone diseases. Materials and Methods: IL-8 mRNA levels were measured using RT-PCR analysis. MAPK phosphorylation was examined using the Western blot method. siRNA was used to inhibit the expression of TGF-beta 1, BMP-2, and IGF-1. DNA affinity protein-binding assay and chromatin immunoprecipitation assays were used to study in vitro and in vivo binding of c- fos, c-jun, p65, and p50 to the IL-8 promoter. A transient transfection protocol was used to examine IL-8, NF-kappa B, and activator protein (AP)-1 activity. Results: Osteoblast conditioned medium (OBCM) induced activation of IL-8, AP-1, and NF-kappa B promoter in human cancer cells. Osteoblasts were transfected with TGF-beta 1, BMP-2, or IGF-1 small interfering RNA, and the medium was collected after 48 h. TGF-beta 1 but not BMP-2 or IGF-1. siRNA inhibited OBCM- induced IL-8 release in human cancer cells. In addition, TGF -beta 1 also directly induced IL-8 release in human cancer cells. Activation of AP-1. and NF-kappa B DNA-protein binding and MAPKs after TGF-beta 1 treatment was shown, and TGF-beta 1-induced IL-8 promoter activity was inhibited by the specific inhibitors of MAPK cascades. Conclusions: In this study, we provide evidence to show that the osteoblasts release growth factors, including TGF-beta 1, BMP-2, and IGF-1. TGF-beta 1 is the major contributor to the activation of extracellular signal-related kinase (ERK), p38, and c- Jun N-terminal kinase (JNK), leading to the activation of AP -1 and NF-kappa B on the IL-8 promoter and initiation of IL- 8 mRNA and protein release, thereby promoting osteoclastogenesis.
|Appears in Collections:||醫學系|
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