Characterization of the Secreted Form of Endothelial-Cell-Specific Molecule 1 by Specific Monoclonal Antibodies

Abstract

Endothelial-cell-specific molecule 1 (ESM-1) is a recently identified endothelial cell molecule. As ESM-1 mRNA is preferentially expressed in human lung and kidney tissues, and as ESM-1 mRNA expression is regulated by inflammatory cytokines, ESM-1 is thought to play a role in the vascular contribution to organ-specific inflammation. In order to define its behavior, mouse anti-ESM-1 monoclonal antibodies were developed, and three distinct epitopes were mapped, which allowed development of a specific ELISA assay, immunohistological staining and immunoblot analysis. Here, we demonstrate that ESM-1 is present in cell lysates of human endothelial cells (human umbilical vein endothelial cells) with an apparent molecular weight of 20 kD. In contrast, the secreted form of ESM-1 is shifted to an apparent molecular weight of 50 kD, indicating that the secreted form of ESM-1 is posttranslationally modified. By ELISA, we show that the secretion of ESM-1 is significantly enhanced in the presence of TNFα. In contrast, the spontaneous as well as TNFα-induced secretion of ESM-1 is strongly inhibited by IFNγ. Moreover, ESM-1 was detected in the serum of healthy subjects at an average concentration of 1.08 ng/ml, and we demonstrated that the serum level of ESM-1 is dramatically increased in patients presenting a septic shock. Analysis of ESM-1 expression in normal human tissues by immunohistochemistry showed that ESM-1 is localized in the vascular network, but also in the bronchial and renal epithelia. Our results demonstrate that ESM-1 is mainly expressed in the vascular endothelium both in vitro and in vivo, but also by different epithelia. ESM-1 may represent a new marker of endothelial cell activation, and may have a functional role in endothelium-dependent pathological disorders.

Endocan Is a Novel Chondroitin Sulfate/Dermatan Sulfate Proteoglycan That Promotes Hepatocyte Growth Factor/Scatter Factor Mitogenic Activity

“…Human HGF/SF was from R & D Systems (Abingdon, UK), and heparin was from Sigma. Anti-endocan monoclonal antibodies were produced and purified as described previously (40).…”

“…The synthesis and secretion of ESM-1 are up-regulated by tumor necrosis factor, interleukin-1, and lipopolysaccharide and down-regulated by interferon-␥ (40). ESM-1 can regulate CD11a/CD18 integrin (LFA-1)-mediated activation of leukocytes through binding to the LFA-1 and its ability to inhibit ICAM-1 binding (41).…”

Endocan: A new marker for cancer and a target for cancer therapy

“…Endocan is highly restricted to endothelial cells, which may contribute to vascular endothelial cells, and endothelial cells play a role in dependent pathological processes (15). Thus, endocan can be used as a new endothelial cell activation marker (15).…”

“…Endocan is highly restricted to endothelial cells, which may contribute to vascular endothelial cells, and endothelial cells play a role in dependent pathological processes (15). Thus, endocan can be used as a new endothelial cell activation marker (15). Although identified in numerous experiments, endocan and vascular proliferation showed a positive correlation, but the mechanism of endocan directly promoting angiogenesis remains to be revealed.…”

Endocan as a Biomarker of Endothelial Dysfunction in Cancer

“…Not all the patients respond to these drugs and as observed in preclinical models, there have been concerns that anti-VEGF therapies increase hypoxia and thereby treatment resistance (Bergers and Hanahan, 2008 Strasser et al, 2010). Moreover, the presence of endocan in the blood flow has been shown to be strictly reflecting the vascular integrity and the health of the body vasculature as validated in sepsis where endothelium is clearly challenged (Bechard et al, 2000;Scherpereel et al, 2006). The capability to monitor patient response through the read out of the vascular integrity can be useful to identify drugs that may benefit to specific populations of cancer patients.…”