Pathogenic roles of decoy receptor 3 (DcR3) in tumor angiogenesis, osteoclast differentiation and inflammatory modulation
| Autor: | Chia-Ron Yang, 楊家榮 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 Recent evidence indicates that the decoy receptor 3 (DcR3) of the TNF receptor superfamily can prevent cytokine responses of FasL, LIGHT and TL1A by binding and neutralization. In addition, it has been demonstrated that DcR3 is up-regulated in various types of cancers, therefore DcR3 is regarded as an immuno-suppressor to down-regulate immunosurveillance of FasL and LIGHT functions. To understand the other possible roles of DcR3 in promoting tumor progress, this study is divided into three sections to delineate the pathological roles of DcR3 in angiogenesis, osteoclast formation and inflammation. TL1A is a member of the TNF superfamily and plays an important role in regulating endothelial cell apoptosis. Previous study shows TL1A is able to interact with death receptor 3 (DR3) and DcR3. Here we demonstrate that DcR3 is able to induce angiogenesis in human umbilical vein endothelial cells (HUVEC). DcR3 promotes HUVEC proliferation, migration and up-regulates matrix metalloproteinase-2 (MMP-2) mRNA expression and enzyme activity. Furthermore, DcR3 enhances EC differentiation into cord vascular-like structures in vitro as well as neovascularization in vivo. The effects of DcR3 on HUVEC are also mimicked by anti-TL1A and anti-DR3 antibodies. In contrast, human aortic endothelial cells (HAEC), which do not express TL1A, are not responsive to DcR3 treatment, including cell proliferation, migration and angiogenic differentiation. These data demonstrate DcR3 might not only help tumor cells to escape immune surveillance, but also induce angiogenesis by blocking TL1A action in EC. The pathological role of DcR3 in promoting cancer progress raises the possibility to target DcR3 for anti-angiogenic therapy in the future. Recent evidence indicates that DcR3 can modulate monocyte function through reverse signaling. We show in this work that DcR3 can induce osteoclast formation from human monocytes, murine RAW264.7 macrophages, and bone marrow cells. DcR3-differentiated cells exhibit characteristics unique for osteoclasts, including polynuclear giant morphology, bone resorption, TRAP, CD51/61 and MMP-9 expression. Consistent with the abrogation of osteoclastogenic effect of DcR3 by TNFR-Fc, DcR3 treatment can induce osteoclastogenic cytokine TNF-a release through ERK, p38 MAPK signaling pathways. We conclude that DcR3 via coupling reverse signaling of ERK and p38 MAPK and stimulating TNF-a synthesis is a critical regulator of osteoclast formation. This action of DcR3 might play an important role in significant osteoclastic activity in osteoclastic bone metastases. To elucidate the role of DcR3 in inflammation, we herein show that HUVECs pretreated with DcR3 enhances the adhesion of the monocytic cells, THP-1 and U937. Flow cytometry and ELISA show that DcR3-treated HUVECs exhibit significant increases in ICAM-1 and VCAM-1 expressions, while the expressions of adhesion molecules in monocytes were not changed. We also show the ability of DcR3 to increase the secretion of IL-8 from HUVECs. Co-incubation of antibodies of ICAM-1, VCAM-1, and IL-8 abolish the DcR3-induced adhesion effect. RT-PCR and reporter assays reveal that the expressions of adhesion molecules and IL-8 are through gene transcription. Experiment with PDTC indicates involvement of the NF-κB signaling pathway. Supporting this notion, DcR3 induces IKK activation, IκB degradation, p65 nuclear translocation, and NF-κB-DNA-binding activity. The enhanced cell adhesion by DcR3 in HUVECs is not mimicked by the TL1A antibody, which has been shown to elicit angiogenesis through neutralizing endogenous TL1A. Moreover, DcR3-induced cell adhesion could be detected in HAEC where TL1A expression is lacking. Taken together, we demonstrate that DcR3 increases monocyte adhesion to EC via activation of NF-κB signaling, thereby transcriptionally upregulating adhesion molecules and IL-8 in EC. This novel action appears not to be due to TL1A neutralization, but occurs through an as yet undefined target(s). This study implicates a role of DcR3 in the relationship between inflammation and cancer development. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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