Hepatocyte growth factor activator inhibitor type 1 inhibits protease activity and proteolytic activation of human airway trypsin-like protease.
ABSTRACT Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a Kunitz-type transmembrane serine protease inhibitor initially identified as a potent inhibitor of hepatocyte growth factor activator (HGFA), a serine protease that converts pro-HGF to the active form. HAI-1 also has inhibitory activity against serine proteases such as matriptase, hepsin and prostasin. In this study, we examined effects of HAI-1 on the protease activity and proteolytic activation of human airway trypsin-like protease (HAT), a transmembrane serine protease that is expressed mainly in bronchial epithelial cells. A soluble form of HAI-1 inhibited the protease activity of HAT in vitro. HAT was proteolytically activated in cultured mammalian cells transfected with its expression vector, and a soluble form of active HAT was released into the conditioned medium. The proteolytic activation of HAT required its own serine protease activity. Co-expression of the transmembrane full-length HAI-1 inhibited the proteolytic activation of HAT. In addition, full-length HAI-1 associated with the transmembrane full-length HAT in co-expressing cells. Like other target proteases of HAI-1, HAT converted pro-HGF to the active form in vitro. These results suggest that HAI-1 functions as a physiological regulator of HAT by inhibiting its protease activity and proteolytic activation in airway epithelium.
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ABSTRACT: Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a membrane-bound serine protease inhibitor that is expressed on the surface of epithelial and carcinoma cells. On the cell surface, HAI-1 regulates membrane-anchored serine proteases with matriptase being the most critical target. Matriptase is involved in pericellular processing of biologically active molecules, including protease-activated receptor-2 (PAR-2). Previously we reported that S2-CP8 cells, a metastatic variant of the SUIT-2 human pancreatic adenocarcinoma cell line, showed markedly decreased HAI-1 expression. To assess the significance of HAI-1 loss in invasion and spontaneous metastasis of S2-CP8 cells, we established stable S2-CP8 sublines that expressed HAI-1 under the control of a tetracycline-regulated promoter. In vitro migration and Matrigel invasion assays revealed inhibitory effects of HAI-1 on S2-CP8 cell migration and invasion. Matriptase activity was suppressed by the expression of HAI-1. As the enhanced invasiveness in the absence of HAI-1was alleviated by knockdown of matriptase by 81% and of PAR-2 completely and PAR-2 antagonist also suppressed the invasion, matriptase-mediated PAR-2 activation is involved in HAI-1 loss-induced invasion of S2-CP8 cells. We then analyzed the effect of HAI-1 expression on metastasis of S2-CP8 cells in vivo using a nude mouse orthotopic xenograft model. Although about 50% of control mice developed distant metastasis, mice treated with doxycycline to induce HAI-1 expression did not develop metastasis. These data indicate that HAI-1 loss contributes to invasion and dissemination of a highly metastatic subline of SUIT-2, suggesting crucial roles for the balance of pericellular serine proteases/inhibitors in pancreatic cancer progression. This article is protected by copyright. All rights reserved.Cancer Science 10/2013; · 3.48 Impact Factor
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ABSTRACT: Myelodysplastic syndromes (MDS) are clonal disorders involving hematopoietic stem cells (HSC) characterized by ineffective hematopoiesis. In addition to HSC defects, a defective hematopoiesis supporting capacity of mesenchymal stromal cells (MSC) in the microenvironment niche has been implicated in MDS pathophysiology. The interaction between the dysfunctional MSC MDS and HSC regulates diverse adhesion-related processes, such as progenitor cell survival, proliferation, differentiation and self-renewal. As previously reported, a microarray analysis identified SPINT2, an inhibitor of HGF activation, to be downregulated in MSC from MDS patients. To define the role of SPINT2 in MDS hematopoietic microenvironment, an analysis of the effect of SPINT2 silencing in MSC was carried out. We herein reported significantly lower levels of SPINT2 whereas HGF was expressed at higher levels in MSC from MDS patients compared to healthy controls. SPINT2 underexpression results in an increased expression, production and secretion of HGF and SDF-1 by MSC. An increased adhesion of normal HSC or malignant cells onto mesenchymal stromal cells silenced for SPINT2 was also observed. The altered MSC adhesion in SPINT2 knockdown cells was correlated with increased CD49b and CD49d expressions and with a decrease in CD49e expression. Our results suggest that the SPINT2 underexpression in the mesenchymal stromal cells from MDS patients is probably involved in the adhesion of progenitors to the bone marrow niche, through an increased HGF and SDF-1 signaling pathway.Stem cells and development 01/2014; · 4.15 Impact Factor
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ABSTRACT: Over the last two decades, cell surface proteases belonging to the type II transmembrane serine protease (TTSP) family have emerged as important enzymes in the mammalian degradome, playing critical roles in epithelial biology, regulation of metabolic homeostasis, and cancer. Human airway trypsin-like protease 5 (HATL5) is one of the few family members that remains uncharacterized. Here we demonstrate that HATL5 is a catalytically active serine protease that is inhibited by the two Kunitz type serine protease inhibitors, hepatocyte growth factor activator inhibitor (HAI)-1 and 2, as well as by serpinA1. Full-length HATL5 is localized on the cell surface of cultured mammalian cells as demonstrated by confocal microscopy. HATL5 displays a relatively restricted tissue expression profile, with both transcript and protein present in the cervix, esophagus, and oral cavity. Immunohistochemical analysis revealed an expression pattern where HATL5 is localized on the cell surface of differentiated epithelial cells in the stratified squamous epithelia of all three of these tissues. Interestingly, HATL5 is significantly decreased in cervical, esophageal, and head and neck carcinomas as compared to normal tissue. Analysis of cervical and esophageal cancer tissue arrays demonstrated that the squamous epithelial cells lose their expression of HATL5 protein upon malignant transformation.PLoS ONE 01/2014; 9(2):e87675. · 3.73 Impact Factor