Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endostatin is a 20 kDa carboxyl-terminal fragment of collagen XVIII that, when added exogenously, inhibits endothelial proliferation and migration in vitro and angiogenesis and tumor growth in vivo. Previous results showed endostatin/collagen XVIII labeling in few endothelial cells in human glioblastoma multiforme. We have now observed constitutive release of endostatin from one of four endothelial cell lines. Induction of endostatin release was observed after H2O2, an in vitro model of cell stress, CoCl2, a model of hypoxia, and by IFN-gamma challenge. Endostatin expression and release was reduced by the nitric oxide synthase inhibitors aminoguanidine and L-NAME and induced by the NO synthase-independent NO donors sodium nitroprusside (SNP) and spermine-NONO-ate. SNP-mediated endostatin induction was abrogated by the soluble guanylate cyclase inhibitor 1H-(1.2.4) oxadiazolo (4,3-A) quinoxalin-1-one. Adenoviral endostatin transduction resulted in the release of endostatin from endothelial cells and in down-regulation of iNOS (NOS2) and eNOS (NOS3), and surprisingly in a 10% induction of PCNA. These results describe the modulation of endostatin release by the NO signaling cascade and provide important new pharmacological information for the systemic induction of endogenous endostatin release by common NO donor pharmacotherapy.
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PMID:Endothelial endostatin release is induced by general cell stress and modulated by the nitric oxide/cGMP pathway. 1283 91

Endostatin was suggested to be an antiangiogenic agent with the potential for clinical use in cancer therapy. Unfortunately, up to now no antiangiogenic effect was seen in clinical trials using this substance. The lack of response might be caused by an incomplete understanding of endostatin signaling. Endostatin is known to influence the vascular endothelial growth factor (VEGF) signaling pathway. It has been reported to bind to the VEGF receptor KDR directly and to decrease the phosphorylation of endothelial nitric oxide synthase (eNOS) at Ser1177 via the protein phosphatase 2A (PP2A). But so far no details of endostatin signaling with regard to NO downstream effectors have been revealed. In the present work the authors demonstrate that endostatin down-regulates the protein level of soluble guanylate cyclase (sGC) in endothelial cells of newly formed blood vessels in 5 day-old wounds (control: 62.5 +/- 33 vessels/mm2, endostatin: 9.2 +/- 3.2 vessels/mm2). This was confirmed in experiments with endothelial tubes of embryoid bodies and endothelial cells derived from embryonic stem cells (eESCs; control: 126 +/- 20, endostatin: 58 +/- 10). The decrease of sGC protein levels in response to endostatin was abolished after preincubation with the PP2A inhibitor okadaic acid. No alterations of sGC mRNA levels could be found under endostatin treatment in eESC. The authors conclude that endostatin affects VEGF signaling in endothelial cells by a post-transcriptional PP2A-dependent down-regulation of sGC protein levels.
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PMID:Endostatin down-regulates soluble guanylate cyclase (sGC) in endothelial cells in vivo: influence of endostatin on vascular endothelial growth factor (VEGF) signaling. 1641 Feb 24