Protease-activated receptor-2 regulates cell proliferation and enhances cyclooxygenase-2 mRNA expression in human pancreatic cancer cells

PAR2: The Cornerstone of Pancreatic Diseases

It has been 30 years since the first member of the protease-activated receptor (PAR) family was discovered. This was followed by the discovery of three other receptors, including PAR2. PAR2 is a G protein-coupled receptor activated by trypsin site-specific proteolysis. The process starts with serine proteases acting between arginine and serine, creating an N-terminus that functions as a tethered ligand that binds, after a conformational change, to the second extracellular loop of the receptor, leading to activation of G-proteins. The physiological and pathological functions of this ubiquitous receptor are still elusive. This review focuses on PAR2 activation and its distribution under physiological and pathological conditions, with a particular focus on the pancreas, a significant producer of trypsin, which is the prototype activator of the receptor. The role in acute or chronic pancreatitis, pancreatic cancer, and diabetes mellitus will be highlighted.

PAR2 induces ovarian cancer cell motility by merging three signalling pathways to transactivate EGFR

BACKGROUND AND PURPOSE

Specific cellular functions mediated by GPCRs are often associated with signalling through a particular G protein or β-arrestin. Here, we examine signalling through a GPCR, protease-activated receptor 2 (PAR2), in a high-grade serous ovarian cancer cell line (OV90).

EXPERIMENTAL APPROACH

Human ovarian cancer tissues (n = 1,200) and nine human ovarian cancer cell lines were assessed for PAR2 expression. PAR2 signalling mechanisms leading to cell migration and invasion were dissected using cellular assays, western blots, CRISPR-Cas9 gene knockouts, pharmacological inhibitors of PAR2 and downstream signalling proteins in OV90 cancer cells.

KEY RESULTS

PAR2 was significantly overexpressed in clinical ovarian cancer tissues and in OV90 ovarian cancer cells. PAR2 agonists, an endogenous protease (trypsin) and a synthetic peptide (2f-LIGRL-NH₂ ), induced migration and invasion of OV90 ovarian cancer cells through activating a combination of Gα_q/11 , Gα_12/13 and β-arrestin1/2, but not Gα_s or Gα_i . This novel cooperative rather than parallel signalling resulted in downstream serial activation of Src kinases, then transactivation of epidermal growth factor receptor (EGFR), followed by downstream MEK-ERK1/2-FOS/MYC/STAT3-COX2 signalling. Either a PAR2 antagonist (I-191), CRISPR-Cas9 gene knockouts (PAR2 or Gα proteins or β-arrestin1/2), or inhibitors of each downstream protein attenuated human ovarian cancer cell motility.

CONCLUSION AND IMPLICATIONS

This study highlights a novel shared signalling cascade, requiring each of Gα_q/11 , Gα_12/13 and β-arrestin1/2 for PAR2-induced ovarian cancer cell migration and invasion. This mechanism controlling a cellular function is unusual in not being linked to a specific individual G protein or β-arrestin-mediated signalling pathway.

Proteinase-activated receptor 2 promotes 3T3-L1 preadipocyte differentiation through activation of the PI3K/AKT signalling pathway and MAT2A gene expression

The present study aimed to investigate the function and mechanisms of PAR2 in preadipocyte differentiation. This study found that the expression level of PAR2 was increased during 3T3-L1 mouse preadipocyte differentiation towards adipocytes. In addition, PAR2 overexpression significantly stimulated the expression of adipogenic proteins including ACC1, PPARγ, and SREBF1. Moreover, PAR2 overexpression increased the content of triglyceride (TG) in 3T3-L1 preadipocytes. Knockdown of PAR2 suppressed 3T3-L1 preadipocyte differentiation and adipogenesis. Mechanistically, PAR2 promoted 3T3-L1 preadipocyte differentiation and TG production through activation of the PI3K/AKT signalling pathway and MAT2A gene expression. The research sheds light on the adipogenic effects of PAR2 and its underlying mechanisms. Thus, PAR2 may have therapeutic significance for obesity.

Is There a Trojan Horse to Aggressive Pancreatic Cancer Biology? A Review of the Trypsin-PAR2 Axis to Proliferation, Early Invasion, and Metastasis

Purpose: Pancreatic cancer is one of the most lethal of solid tumors and is associated with aggressive cancer biology. The purpose is to review the role of trypsin and effect on molecular and cellular processes potentially explaining the aggressive biology in pancreatic cancer.

Methods: A narrative literature review of studies investigating trypsin and its effect on protease systems in cancer, with special reference to pancreatic cancer biology.

Results: Proteases, such as trypsin, provides a significant advantage to developing tumors through the ability to remodel the extracellular matrix, promote cell invasion and migration, and facilitate angiogenesis. Trypsin is a digestive enzyme produced by the exocrine pancreas that is also related to mechanisms of proliferation, invasion and metastasis. Several of these mechanisms may be co-regulated or influenced by activation of proteinase-activated receptor 2 (PAR-2). The current role in pancreatic cancer is not clear but emerging data suggest several potential mechanisms. Trypsin may act as a Trojan horse in the pancreatic gland, facilitating several molecular pathways from the onset, which leads to rapid progression of the disease. Pancreatic cancer cell lines containing PAR-2 proliferate upon exposure to trypsin, whereas cancer cell lines not containing PAR-2 fail to proliferate upon trypsin expression. Several mechanisms of action include a proinflammatory environment, signals inducing proliferation and migration, and direct and indirect evidence for mechanisms promoting invasion and metastasis. Novel techniques (such as organoid models) and increased understanding of mechanisms (such as the microbiome) may yield improved understanding into the role of trypsin in pancreatic carcinogenesis.

Conclusion: Trypsin is naturally present in the pancreatic gland and may experience pathological activation intracellularly and in the neoplastic environment, which speeds up molecular mechanisms of proliferation, invasion, and metastasis. Further investigation of these processes will provide important insights into how pancreatic cancer evolves, and suggest new ways for treatment.

Nanomedical strategy to prolong survival period, heighten cure rate, and lower systemic toxicity of S180 mice treated with MTX/MIT

In spite of the usual combination form of methotrexate (MTX)/mitoxantrone (MIT) and various complex combination regimens of MTX/MIT with other anticancer drugs, the survival period, cure rate, and systemic toxicity still need to be improved. For this purpose, a nanostructured amino group-modified mesoporous silica nanoparticles (MSNN)-MTX/MIT was designed. In the preparation, the surface of mesoporous silica nanoparticles (MSNs) was modified with amino groups to form MSNN. The covalent modification of the amino groups on the surface of MSNN with MTX resulted in MSNN-MTX. The loading of MIT into the surface pores of MSNN-MTX produced nanostructured MSNN-MTX/MIT. Compared with the usual combination form (MTX/MIT), nanostructured MSNN-MTX/MIT increased the survival period greatly, heightened the cure rate to a great extent, and lowered the systemic toxicity of the treated S180 mice, significantly. These superior in vivo properties of nanostructured MSNN-MTX/MIT over the usual combination form (MTX/MIT) were correlated with the former selectively releasing MTX and MIT in tumor tissue and inside cancer cells in vitro. The chemical structure and the nanostructure of MSNN-MTX/MIT were characterized using infrared and differential scanning calorimeter spectra as well as transmission electron microscope images, respectively.

Effects of the dihydrolipoyl histidinate zinc complex against carbon tetrachloride-induced hepatic fibrosis in rats

PURPOSE

This study investigated the effects of an antioxidant, dihydrolipoyl histidinate zinc complex (DHLHZn), on the hepatic fibrosis in the carbon tetrachloride (CCl4) rat model.

METHODS

The animals were divided into three groups: control, CCl4, and CCl4+DHLHZn. A histological assessment of the liver fibrosis was performed using stained liver samples. The oxidative stress and antioxidant levels were evaluated by measuring the malondialdehyde (MDA) and glutathione (GSH) levels in the liver. In addition, cultured human hepatic stellate cells (LI90) were exposed to antimycin-A (AMA) and divided into four groups: control, DHLHZn, AMA, and AMA+DHLHZn. The effects of DHLHZn on AMA-induced fibrosis were evaluated by measuring the expression of transforming growth factor (TGF)-β1 and collagen α1 (I).

RESULTS

The hepatic fibrosis in the CCl4+DHLHZn group was attenuated compared to that in the CCl4 group. The MDA levels in the CCl4+DHLHZn group were significantly lower than those of the CCl4 group, whereas the GSH levels in the CCl4+DHLHZn group were significantly higher than those of the CCl4 group. Furthermore, the relative mRNA expression of TGF-β1 and collagen α1 (I) in the AMA+DHLHZn group was significantly lower than that in the AMA group.

CONCLUSION

DHLHZn may attenuate the hepatic fibrosis induced by CCl4 by decreasing the degree of oxidative stress.

Proteinase-activated receptor 2 promotes cancer cell migration through RNA methylation-mediated repression of miR-125b

Proteinase activated-receptor 2 (PAR2) participates in cancer metastasis promoted by serine proteinases. The current study aimed to test the molecular mechanism by which PAR2 promotes cancer cell migration. In different cancer cells, activation of PAR2 by activating peptide (PAR2-AP) dramatically increased cell migration, whereas knock down of PAR2 inhibited cellular motility. The PAR2 activation also repressed miR-125b expression while miR-125b mimic successfully blocked PAR2-induced cell migration. Moreover, Grb associated-binding protein 2 (Gab2) was identified as a novel target gene of miR-125b and it mediated PAR2-induced cell migration. The correlation of PAR2 with miR-125b and Gab2 was further supported by the findings obtained from human colorectal carcinoma specimens. Remarkably, knock down of NOP2/Sun domain family, member 2 (NSun2), a RNA methyltransferase, blocked the reduction in miR-125b induced by PAR2. Furthermore, PAR2 activation increased the level of N(6)-methyladenosine (m(6)A)-containing pre-miR-125b in NSun2-dependent manner. Taken together, our results demonstrated that miR-125b mediates PAR2-induced cancer cell migration by targeting Gab2 and that NSun2-dependent RNA methylation contributes to the down-regulation of miR-125b by PAR2 signaling. These findings suggest a novel epigenetic mechanism by which microenvironment regulates cancer cell migration by altering miRNA expression.

Protease-activated receptor (PAR)1, PAR2 and PAR4 expressions in esophageal squamous cell carcinoma

Here, we used reverse transcription-PCR (RT-PCR) and western blot to detect protease-activated receptor (PAR) 1, PAR 2 and PAR 4 expression in cancer tissues and cell lines of esophageal squamous cell carcinoma, and investigated the co-relationship between PAR expression and clinic-pathological data for esophageal cancer. The methylation of PAR4 gene promoter involved in esophageal carcinoma was also analyzed. By comparing the mRNA expressions of normal esophageal tissue and human esophageal epithelial cells (HEEpiC), we found that among the 28 cases of esophageal squamous cell carcinoma, PAR1 (60%) and PAR2 (71%) were elevated in 17 and 20 cases, respectively, and PAR4 (68%) expression was lowered in 19 cases. Whereas, in human esophageal squamous cells (TE-1 and TE-10), PAR1 and PAR2 expression was increased but PAR4 was decreased. Combined with clinical data, the expression of PAR1 in poorly differentiated (P=0.016) and middle and lower parts of the esophagus (P=0.016) was higher; expression of PAR4 in poorly differentiated carcinoma was lower (P=0.049). Regarding TE-1 and TE-10 protein expression, we found that in randomized esophageal carcinoma, PAR1 (P=0.027) and PAR2 (P=0.039) expressions were increased, but lowered for PAR4 (P=0.0001). In HEEpiC, TE-1, TE-10, esophageal and normal esophagus tissue samples (case No. 7), the frequency of methylation at the 19 CpG loci of PAR4 was 35.4%, 95.2%, 83.8%, 62.6% and 48.2%, respectively. Our results indicate that the expression of PAR1 and PAR2 in esophageal squamous cell carcinoma is increased but PAR4 is decreased. Hypermethylation of the promoter of the PAR4 gene may contribute to reduced expression of PAR4 in esophageal squamous cell carcinoma.

Protease-activated receptor 2 agonist increases cell proliferation and invasion of human pancreatic cancer cells

The aim of this study was to determine the expression of protease-activated receptor 2 (PAR-2) in the human pancreatic cancer cell line SW1990, and to evaluate its effect on cell proliferation and invasion. The expression of PAR-2 protein and mRNA in SW1990 cells was determined by immunocytochemistry and reverse transcription polymerase chain reaction (PCR), respectively. MTT and cell invasion and migration assays, as well as semi-quantitative PCR and zymography analysis, were additionally performed. PAR-2 mRNA was significantly upregulated in the cells treated with trypsin or the PAR-2 activating peptide Ser-Leu-Ile-Gly-Lys-Val (SLIGKV) (P<0.01), but not in the Val-Lys-Gly-Ile-Leu-Ser group (P>0.05). Trypsin and SLIGKV significantly promoted SW1990 cell proliferation in a dose- and time-dependent manner (P<0.05). Compared with the control group, trypsin and SLIGKV significantly increased the mRNA expression (P<0.01) and gelatinolytic activity (P<0.01) of matrix metalloproteinase (MMP)-2. In conclusion, PAR-2 is expressed in SW1990 cells. PAR-2 activation may promote the invasion and migration of human pancreatic cancer cells by increasing MMP-2 expression.

Tumour progression and cancer-induced pain: a role for protease-activated receptor-2?

The role of proteases in modifying the microenvironment of tumour cells has long been recognised. With the discovery of the protease-activated receptor family of G protein-coupled receptors a mechanism for cells to sense and respond directly to proteases in their microenvironment was revealed. Many early studies described the roles of protease-activated receptors in the cellular events that occur during blood coagulation and inflammation. More recently, studies have begun to focus on the roles of protease-activated receptors in the establishment, progression and metastasis of a variety of tumours. This review will focus on the expression of protease-activated receptor-2 and its activators by normal and neoplastic tissues, and describe current evidence that activation of protease-activated receptor-2 is an important event at multiple stages of tumour progression and in pain associated with cancer.

High density of tryptase-positive mast cells in human colorectal cancer: a poor prognostic factor related to protease-activated receptor 2 expression

Tryptase(+) mast cells (MCs), abundant in the invasive front of tumours, contribute to tissue remodelling. Indeed, protease-activated receptor-2 (PAR-2) activation by MC-tryptase is considered an oncogenic event in colorectal cancer (CRC). Recently, we have suggested NHERF1 as a potential new marker in CRC. In this study, we aimed to determine the distribution of tryptase(+) MCs and PAR-2 and to examine the relationship between PAR-2 and NHERF1, investigating their reputed usefulness as tumour markers. We studied a cohort of 115 CRC specimens including primary cancer (C) and adjacent normal mucosa (NM) by immunohistochemical double staining, analyzing the protein expression of MC-tryptase, PAR-2 and cytoplasmic NHERF1. MC density was higher in NM than in C. Tumours with high TNM stage and poor grade showed the highest MC density. A higher PAR-2 immunoreactivity characterized tumours most infiltrated by MCs compared with samples with low MC density. Furthermore, PAR-2 overexpression was associated with advanced TNM stage, poor grade and lymphovascular invasion (LVI). A positive correlation existed between tryptase(+) MC density and PAR-2 expression. Cytoplasmic NHERF1 was higher in C than in NM and overexpressing tumours resulted associated with nodal and distant metastases, poor grade and LVI. PAR-2 correlated with cytoplasmic NHERF1 and the PAR-2(+)/cytoplasmic NHERF1(+) expression immunophenotype identified tumours associated with unfavourable prognosis and aggressive clinical parameters. Our data indicate that the high density of tryptase(+) MCs at invasive margins of tumours was associated with advanced stages of CRC and was strongly correlated with PAR-2 expression.

Proteinase-activated receptors differentially modulate in vitro invasion of human pancreatic adenocarcinoma PANC-1 cells in correlation with changes in the expression of CDC42 protein

OBJECTIVES

Proteinase-activated receptor-1 (PAR-1) and PAR-2 have been associated with increased invasiveness and metastasis in human malignancies. The role of PAR-3 has been less investigated. We examined the role of PARs in a human pancreatic adenocarcinoma PANC-1 cell line phenotype in vitro.

METHODS

We knocked down PAR-1, PAR-2, or PAR-3, whereas empty vector-infected cells served as controls. Specific peptide agonists of PARs were used to stimulate the receptors. In vitro assays of colony formation, migration, and invasion were used to characterize the phenotypes, and Western analysis was used to follow cell division control protein 42 homolog (CDC42) expression.

RESULTS

PAR-1 and PAR-2 knockdowns (KDs) were markedly less, whereas PAR-3 KDs were robustly more migratory and invasive than the controls. Stimulation of PAR-1 or PAR-2 by their peptide agonists increased, whereas PAR-3 agonist reduced the invasion of the control cells. Knockdowns of all three PARs exhibited changes in the expression of CDC42, which correlated with the changes in their invasion. Conversely, stimulation of vector-control cells with PAR-1 or PAR-2 agonists enhanced, whereas PAR-3 agonist reduced the expression of CDC42. In the respective KD cells, the effects of the agonists were abrogated.

CONCLUSION

The expression and/or activation of PARs is linked to the invasiveness of PANC-1 cells in vitro, probably via modulation of the expression of CDC42.

Loss of hepatocyte growth factor activator inhibitor type 1 participates in metastatic spreading of human pancreatic cancer cells in a mouse orthotopic transplantation model

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 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-1 was 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 approximately 50% of the 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.

Protease-activated receptor-2 induces migration of pancreatic cancer cells in an extracellular ATP-dependent manner

BACKGROUND

Protease-activated receptor 2 (PAR-2) is a G protein-coupled receptor suggested to play an important role in the proliferation and migration of tumor cells of epithelial origin. However, the role of PAR-2 in the setting of pancreatic cancer remains largely unexplored.

OBJECTIVES

To understand the importance of PAR-2 in pancreatic cancer cell migration.

METHODS AND RESULTS

The present study shows that PAR-2 does not affect pancreatic cancer cell proliferation but significantly induces the migration of pancreatic cancer cells in scratch assays. Interestingly, PAR-2 does not affect migration in a trans-well setting. This apparent discrepancy depends on extracellular ATP release in the scratch assays and the addition of exogenous (ATP)-induced PAR-2-dependent migration in trans-well assays, whereas a specific P2Y11 receptor antagonist prevents PAR-2-driven migration in scratch assays. In the scratch assays, inhibitors of Src, Rac, protein kinase C, mitogen-activated protein kinase kinase, p38, and epidermal growth factor (EGF) receptor blocked PAR-2-driven migration, whereas they did not affect fetal calf serum-driven wound closure.

CONCLUSION

Taken together, PAR-2 activation drives pancreatic cancer cell migration via an EGF-Src-Rac-p38/mitogen-activated protein kinase kinase/EGF1/2 signaling pathway, which is facilitated by extracellular ATP. Targeting the PAR-2/ATP-driven signaling pathway may therefore limit cell migration, which could inhibit pancreatic cancer metastasis.

Activated PAR-2 regulates pancreatic cancer progression through ILK/HIF-α-induced TGF-α expression and MEK/VEGF-A-mediated angiogenesis

Tissue factor initiates the process of thrombosis and activates cell signaling through protease-activated receptor-2 (PAR-2). The aim of this study was to investigate the pathological role of PAR-2 signaling in pancreatic cancer. We first demonstrated that activated PAR-2 up-regulated the protein expression of both hypoxia-inducible factor-1α (HIF-1α) and HIF-2α, resulting in enhanced transcription of transforming growth factor-α (TGF-α). Down-regulation of HIFs-α by siRNA or YC-1, an HIF inhibitor, resulted in depleted levels of TGF-α protein. Furthermore, PAR-2, through integrin-linked kinase (ILK) signaling, including the p-AKT, promoted HIF protein expression. Diminishing ILK by siRNA decreased the levels of PAR-2-induced p-AKT, HIFs-α, and TGF-α; our results suggest that ILK is involved in the PAR-2-mediated TGF-α via an HIF-α-dependent pathway. Furthermore, the culture medium from PAR-2-treated pancreatic cancer cells enhanced human umbilical vein endothelial cell proliferation and tube formation, which was blocked by the MEK inhibitor, PD98059. We also found that activated PAR-2 enhanced tumor angiogenesis through the release of vascular endothelial growth factor-A (VEGF-A) from cancer cells, independent of the ILK/HIFs-α pathways. Consistent with microarray analysis, activated PAR-2 induced TGF-A and VEGF-A gene expression. In conclusion, the activation of PAR-2 signaling induced human pancreatic cancer progression through the induction of TGF-α expression by ILK/HIFs-α, as well as through MEK/VEGF-A-mediated angiogenesis, and it plays a role in the interaction between cancer progression and cancer-related thrombosis.

Chymase-mediated intestinal epithelial permeability is regulated by a protease-activating receptor/matrix metalloproteinase-2-dependent mechanism

Mast cells regulate intestinal barrier function during disease and homeostasis. Secretion of the mast cell-specific serine protease chymase regulates homeostasis. In the present study, we employ in vitro model systems to delineate the molecular pathways involved in chymase-mediated intestinal epithelial barrier dysfunction. Chymase stimulation of intestinal epithelial (Caco-2 BBe) cell monolayers induced a significant reduction in transepithelial resistance, indicating decreased intestinal epithelial barrier function. The chymase-induced intestinal epithelial barrier dysfunction was characterized by chymase-induced protease-activated receptor (PAR)-2 activation and matrix metalloproteinase (MMP)-2 expression and activation. Consistent with this observation, in vitro analysis revealed chymase-induced PAR-2 activation and increased MAPK activity and MMP-2 expression. Pharmacological and small interfering RNA-mediated antagonism of PAR-2 and MMP-2 significantly attenuated chymase-stimulated barrier dysfunction. Additionally, the chymase/MMP-2-mediated intestinal epithelial dysfunction was associated with a significant reduction in the tight junction protein claudin-5, which was partially restored by MMP-2 inhibition. Finally, incubation of Caco-2 BBe cells with chymase-sufficient, but not chymase-deficient, bone marrow-derived mast cells decreased barrier function, which was attenuated by the chymase inhibitor chymostatin. Collectively, these results suggest that mast cell/chymase-mediated intestinal epithelial barrier function is mediated by PAR-2/MMP-2-dependent pathways.

Mast cell regulation of the immune response

Mast cells are well known as principle effector cells of type I hypersensitivity responses. Beyond this role in allergic disease, these cells are now appreciated as playing an important role in many inflammatory conditions. This review summarizes the support for mast cell involvement in resisting bacterial infection, exacerbating autoimmunity and atherosclerosis, and promoting cancer progression. A commonality in these conditions is the ability of mast cells to elicit migration of many cell types, often through the production of inflammatory cytokines such as tumor necrosis factor. However, recent data also demonstrates that mast cells can suppress the immune response through interleukin-10 production. The data encourage those working in this field to expand their view of how mast cells contribute to immune homeostasis.

Serum deprivation induces glucose response and intercellular coupling in human pancreatic adenocarcinoma PANC-1 cells

OBJECTIVE

This study aimed to investigate whether the previously described differentiating islet-like aggregates of human pancreatic adenocarcinoma cells (PANC-1) develop glucose response and exhibit intercellular communication.

METHODS

Fura 2-loaded PANC-1 cells in serum-free medium were assayed for changes in cytosolic free calcium ([Ca]i) induced by depolarization, tolbutamide inhibition of K(ATP) channels, or glucose. Dye transfer, assayed by confocal microscopy or by FACS, was used to detect intercellular communication. Changes in messenger RNA (mRNA) expression of genes of interest were assessed by quantitative real-time polymerase chain reaction. Proliferation was assayed by the MTT method.

RESULTS

Serum-deprived PANC-1 cell aggregates developed [Ca]i response to KCl, tolbutamide, or glucose. These responses were accompanied by 5-fold increase in glucokinase mRNA level and, to a lesser extent, of mRNAs for K(ATP) and L-type calcium channels, as well as increase in mRNA levels of glucagon and somatostatin. Trypsin, a proteinase-activated receptor 2 agonist previously shown to enhance aggregation, modestly improved [Ca]i response to glucose. Glucose-induced coordinated [Ca]i oscillations and dye transfer demonstrated the emergence of intercellular communication.

CONCLUSIONS

These findings suggest that PANC-1 cells, a pancreatic adenocarcinoma cell line, can be induced to express a differentiated phenotype in which cells exhibit response to glucose and form a functional syncytium similar to those observed in pancreatic islets.

Effect of pertussis toxin and herbimycin A on proteinase-activated receptor 2-mediated cyclooxygenase 2 expression in Helicobacter pylori-infected gastric epithelial AGS cells

Helicobacter pylori (H. pylori) is an important risk factor for chronic gastritis, peptic ulcer, and gastric cancer. Proteinase-activated receptor 2 (PAR2), subgroup of G-protein coupled receptor family, is highly expressed in gastric cancer, and chronic expression of cyclooxygenase-2 (COX-2) plays an important role in H. pylori-associated gastric carcinogenesis and inflammation. We previously demonstrated that H. pylori induced the expression of PAR2 and COX-2 in gastric epithelial cells. Present study aims to investigate whether COX-2 expression induced by H. pylori in Korean isolates is mediated by PAR2 via activation of G(i) protein and Src kinase in gastric epithelial AGS cells. Results showed that H. pylori-induced COX-2 expression was inhibited in the cells transfected with antisense oligonucleotide for PAR2 or treated with Gi protein blocker pertussis toxin, Src kinase inhibitor herbimycin A and soybean trypsin inbitor, indicating that COX-2 expression is mediated by PAR2 through activation of Gi protein and Src kinase in gastric epithelial cells infected with H. pylori in Korean isolates. Thus, targeting the activation of PAR2 may be beneficial for prevention or treatment of gastric inflammation and carcinogenesis associated with H. pylori infection.

Cancer stem cell-related factors are associated with the efficacy of pre-operative chemoradiotherapy for locally advanced rectal cancer

Pre-operative chemoradiotherapy (CRT) is an important neoadjuvant therapy for locally advanced rectal cancer. In the present study, we investigated the factors that influence the efficacy of pre-operative CRT in locally advanced rectal cancer. We divided 50 patients with locally advanced rectal carcinoma treated with pre-operative CRT into two groups according to the grade of tumor response to pre-operative CRT: low-sensitivity group and high-sensitivity group. As candidates for the prediction of sensitivity to pre-operative CRT, clinicopathological factors and 12 biomarkers, including factors related to tumor growth, cell cycle, apoptosis, tumor stroma and cancer stem cells, were examined immunohistochemically in 48 resected specimens. Thirty-one tumors showed high sensitivity and 19 showed low sensitivity to pre-operative CRT. The status of stem cell-related factors, CD133 and CD24, was significantly associated respectively with sensitivity to pre-operative CRT (P=0.003, P=0.029). In 10 tumors positive for both CD133 and CD24, low sensitivity to CRT was found in 9 (90%), whereas in 16 tumors negative for both CD133 and CD24, low sensitivity was found in 3 (19%). Other pathological parameters were not associated with tumor response to pre-operative CRT. In conclusion, overexpression of cancer stem cell-related factors, CD133 and CD24, is associated with the sensitivity of locally advanced rectal cancer to pre-operative CRT.

Profiling gene expression induced by protease-activated receptor 2 (PAR2) activation in human kidney cells

Protease-Activated Receptor-2 (PAR2) has been implicated through genetic knockout mice with cytokine regulation and arthritis development. Many studies have associated PAR2 with inflammatory conditions (arthritis, airways inflammation, IBD) and key events in tumor progression (angiogenesis, metastasis), but they have relied heavily on the use of single agonists to identify physiological roles for PAR2. However such probes are now known not to be highly selective for PAR2, and thus precisely what PAR2 does and what mechanisms of downstream regulation are truly affected remain obscure. Effects of PAR2 activation on gene expression in Human Embryonic Kidney cells (HEK293), a commonly studied cell line in PAR2 research, were investigated here by comparing 19,000 human genes for intersecting up- or down-regulation by both trypsin (an endogenous protease that activates PAR2) and a PAR2 activating hexapeptide (2f-LIGRLO-NH(2)). Among 2,500 human genes regulated similarly by both agonists, there were clear associations between PAR2 activation and cellular metabolism (1,000 genes), the cell cycle, the MAPK pathway, HDAC and sirtuin enzymes, inflammatory cytokines, and anti-complement function. PAR-2 activation up-regulated four genes more than 5 fold (DUSP6, WWOX, AREG, SERPINB2) and down-regulated another six genes more than 3 fold (TXNIP, RARG, ITGB4, CTSD, MSC and TM4SF15). Both PAR2 and PAR1 activation resulted in up-regulated expression of several genes (CD44, FOSL1, TNFRSF12A, RAB3A, COPEB, CORO1C, THBS1, SDC4) known to be important in cancer. This is the first widespread profiling of specific activation of PAR2 and provides a valuable platform for better understanding key mechanistic roles of PAR2 in human physiology. Results clearly support the development of both antagonists and agonists of human PAR2 as potential disease modifying therapeutic agents.

Protease-activated receptor-2 regulates cyclooxygenase-2 expression in human bile duct cancer via the pathways of mitogen-activated protein kinases and nuclear factor kappa B

BACKGROUND/PURPOSE

Recent studies have suggested that protease-activated receptor-2 (PAR-2) activity correlates with cell proliferation and tumor growth, and its activation induces expression of cyclooxygenase-2 (COX-2). However, no previous reports have investigated PAR-2 signaling pathways in bile duct cancer. The aim of this study was to determine whether PAR-2 activation can regulate COX-2 expression via mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) in human bile duct cancer cells.

METHODS

We immunohistochemically examined PAR-2 and COX-2 expression in 104 resected human specimens of extrahepatic bile duct cancer. We then determined how inhibitors of MAPKs and NF-κB signaling pathways influence COX-2 expression under PAR-2 activation in HuCCT1 and TKKK, human bile duct cancer cell lines.

RESULTS

PAR-2 and COX-2 proteins were immunohistochemically recognized in 63 and 57% of specimens and were significantly correlated. PAR-2 agonist peptide activated mRNA and protein expression of COX-2 in HuCCT1 and TKKK. Pharmacologic blockade of p44/42 or p38 MAPK significantly inhibited PAR-2-activated mRNA and protein expression of COX-2 in both cells. COX-2 protein expression was also inhibited by the blocker of NF-κB pathway in both cells.

CONCLUSIONS

PAR-2 may regulate COX-2 expression in human bile duct cancer via the MAPKs and NF-κB pathways.

Prognostic Value of Protease-Activated Receptor 2 Expression in Oesophageal Squamous Cell Carcinoma

Protease-activated receptor-2 (PAR-2) is essential for the initiation and development of tumours, suggesting that the detection of PAR-2 expression might serve as a clinical marker in the prediction or diagnosis of clinical outcomes of malignant neoplasia. Using immunohisto chemical methods, this study investigated whether the detection of PAR-2 protein had clinical implications for patients with oesophageal squamous cell carcinoma (OSCC). PAR-2 protein was present at a high level in primary OSCC sites but at a low level in normal oesophageal tissue. The level of PAR-2 protein in tumours was significantly correlated with the clinical stage and histological grade of disease. Patients with tumours highly positive for PAR-2 protein had a significantly worse prognosis than those with lower PAR-2 levels. Thus, the over-expression of PAR-2 is a characteristic feature of OSCC and suggests that the immuno histochemical detection of raised levels of PAR-2 may be a potentially useful prognostic indicator.

Proteinase-activated receptor 2 expression in breast cancer and its role in breast cancer cell migration

Proteinase-activated receptor 2 (PAR2) is a G protein-coupled receptor that is activated by trypsin-like proteinases. PAR2 is detected in breast tumor specimens; however, it is not clear how PAR2 level in breast cancer cell/tissues compares with normal cell/tissues. Here, we show the elevation of PAR2 protein level in 76 of 105 breast tumor specimens but only 5 of 24 normal breast tissues. PAR2 level is also higher in breast cancer cell lines than that in normal breast cells and non-cancerous breast cell lines. To determine the role of PAR2 in breast carcinogenesis, we examined the effect of PAR2 agonists on cell proliferation and migration. Our studies show that PAR2 agonists (PAR2-activating peptide and trypsin) are neither potent growth enhancers nor chemoattractants to breast cancer cells. Instead, PAR2 agonists induce significant chemokinesis. PAR2-mediated chemokinesis is G(alphai)-dependent, and inhibiting Src kinase activity or silencing c-Src expression blocks PAR2-mediated chemokinesis. These results suggest that c-Src works downstream of G(alphai) to mediate this PAR2 agonist-induced event. To characterize c-Src effector, we reveal that PAR2 agonists activate JNKs in a Src-dependent manner and that JNK activity is essential for PAR2-mediated chemokinesis. Moreover, PAR2 agonist stimulation leads to paxillin Ser(178) phosphorylation and paxillin(S178A) mutant inhibits PAR2-mediated chemokinesis. In conclusion, our studies show that PAR2 agonists facilitate breast cancer cell chemokinesis through the G(alphai)-c-Src-JNK-paxillin signaling pathway.

Increased heat-shock protein 90 expression contributes to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rats

BACKGROUND AND AIMS

Portal hypertensive (PHT) gastropathy results in an increased susceptibility to damage. Adaptive cytoprotection against ethanol-induced damage is impaired in the gastric mucosa of rats with portal hypertension. Excessive nitric oxide (NO) production occurs in portal hypertension and is mediated in part via heat-shock protein (Hsp)90 production. The aim of this study was to investigate the relation between adaptive cytoprotection after exposure to ethanol and gastric expression of Hsp90 in PHT rats.

METHODS

Portal hypertension was induced in rats by staged portal vein occlusion. Adaptive cytoprotection to 70% ethanol was evaluated by assessing the injury index of the gastric mucosa with or without pretreatment with 10% ethanol. Expression of Hsp90 mRNA was evaluated by real-time polymerase chain reaction, and expression of Hsp90 protein was evaluated by western blotting. The effect of Hsp90 inhibition in PHT rats was evaluated by administration of geldanamycin.

RESULTS

Gastric Hsp90 mRNA expression in PHT rats was significantly less than that in sham-operated (SO) controls. However, after 10% ethanol pretreatment, Hsp90 mRNA expression was significantly greater in PHT rats than in SO controls. In PHT rats, gastric Hsp90 protein expression after 10% ethanol pretreatment was significantly greater than that without the pretreatment. However, the pretreatment had no effect on the injury index compared to SO rats. Administration of geldanamycin prior to 10% ethanol pretreatment significantly decreased the injury index in response to 70% ethanol in the PHT rats.

CONCLUSIONS

These results show that 10% ethanol pretreatment markedly increases gastric Hsp90 expression in PHT rats. Excessive production of Hsp90 may contribute impaired adaptive cytoprotection.

Potential role of protease-activated receptor-2-stimulated activation of cytosolic phospholipase A(2) in intestinal myofibroblast proliferation: Implications for stricture formation in Crohn's disease

BACKGROUND AND AIMS

Myofibroblast hyperplasia contributes to muscularis mucosae thickening and stricture formation in Crohn's disease (CD). Protease-activated receptor-2 (PAR-2) and cytosolic phospholipase A(2) (cPLA(2)) are known regulators of cell growth, but their significance in intestinal myofibroblast proliferation remain to be elucidated. The principle aims of the present study were to investigate if PAR-2 is expressed in the expanded muscularis mucosa in ileal CD specimens, if inflammatory cytokines may stimulate PAR-2 expression in intestinal myofibroblasts, and if PAR-2 and cPLA(2) may regulate intestinal myofibroblast growth.

METHODS

Immunohistochemistry was used for detection of PAR-2 in ileal CD specimens. Studies on PAR-2 expression, PLA(2) activation and cell growth were performed in a human intestinal myofibroblast cell line, CCD-18Co. PAR-2 expression was investigated by RT-PCR and immunocytochemistry. PLA(2) activity was analyzed by quantification of released (14)C-arachidonic acid ((14)C-AA). Cell growth was examined by (3)H-thymidine incorporation and cell counting.

RESULTS

The thickened muscularis mucosae of the CD specimens showed strong PAR-2 expression. In cultured myofibroblasts, tumor necrosis factor-α (TNF-α) up-regulated PAR-2 mRNA and protein, and potentiated PAR-2-stimulated (14)C-AA release by two known PAR-2 activators, trypsin and SLIGRL-NH(2). The release of (14)C-AA was dependent on cPLA(2). Trypsin stimulated the proliferation of serum-starved cells, and inhibition of cPLA(2) reduced normal cell growth and abolished the growth-promoting effect of trypsin.

CONCLUSIONS

The results suggest that PAR-2-mediated cPLA(2) activation might be of importance in intestinal myofibroblast proliferation. The results also point to the possibility that PAR-2 up-regulation by inflammatory cytokines, like TNF-α, may modulate this effect.

CUX1 transcription factor is a downstream effector of the proteinase-activated receptor 2 (PAR2)

Proteinase-activated receptors (PARs) are G-protein-coupled receptors that have been linked to an array of cellular processes, including inflammation, migration, and proliferation. Although signal transduction downstream of PARs has been actively investigated, little is known about the mechanisms that lead to changes in transcriptional programs. Here we show that the CUX1 homeodomain protein is a downstream effector of PAR2. Treatment of epithelial and fibroblastic cells with trypsin or the PAR2-activating peptide (PAR2-AP) caused a rapid increase in CUX1 DNA binding activity. The stimulation of CUX1 was specific to PAR2 because no effect was observed with thrombin or the PAR1-AP. Using a panel of recombinant CUX1 proteins, the regulation was found to involve the cut repeat 3 (CR3) and the cut homeodomain, two DNA binding domains that are present in all CUX1 isoforms. Expression analysis in cux1(-/-) mouse embryo fibroblasts led to the identification of three genes that are regulated downstream of both PAR2 and CUX1 as follows: interleukin-1alpha, matrix metalloproteinase-10, and cyclo-oxygenase-2. p110 CUX1 was able to activate each of these genes, both in reporter assays and following the infection of cells. Moreover, the treatment of Hs578T breast tumor cells with trypsin led to a rapid recruitment of p110 CUX1 to the promoter of these genes and to a concomitant increase in their mRNA steady-state levels. Altogether, these results suggest a model whereby activation of PAR2 triggers a signaling cascade that culminates with the stimulation of p110 CUX1 DNA binding and the transcriptional activation of target genes.

Effect of bevacizumab, a humanized monoclonal antibody to vascular endothelial growth factor, on peritoneal metastasis of MNK-45P human gastric cancer in mice

BACKGROUND

The aim of this study was to clarify the effect of bevacizumab on gastric cancer with peritoneal metastasis in nude mice.

MATERIALS AND METHODS

The expression of vascular endothelial growth factor mRNA (VEGF mRNA) in four gastric cancer cell lines, NCI-N87, MKN-45, MKN-45P, and Kato-III, was examined by polymerase chain reaction. We created a model of peritoneal metastasis by injecting mice with the human gastric cancer cell line MKN-45P. Mice were injected intraperitoneally with bevacizumab (0.1 mg/100 microL) on days 5-14, after inoculation (n = 10) or with phosphate-buffered saline (PBS) over the same time period (n = 10). The maximum abdominal circumference, ascites volume, and the total number and weight of peritoneal tumors were measured. To assess the effect of bevacizumab on angiogenesis, immunohistochemical analysis was performed.

RESULTS

VEGF mRNA was expressed at a high level in MKN-45P cells as well as MKN-45 and Kato-III. The mean maximum abdominal circumference and ascites volume in the bevacizumab group were significantly less than those in the control group (P < 0.001, respectively). The total weight of disseminated tumors in the bevacizumab group was also significantly less than that in the control group (P < 0.01). In addition, immunohistochemical analysis of CD31-stained peritoneally disseminated nodules showed that the vessel area in the bevacizumab group was significantly less than that in the control group (P < 0.001).

CONCLUSIONS

These results show that intraperitoneal administration of bevacizumab inhibits peritoneal metastasis and reduces malignant ascites in tumor-bearing mice.

Proteinase-activated receptor 2 (PAR-2) in gastrointestinal and pancreatic pathophysiology, inflammation and neoplasia

Of all the body systems, the gastrointestinal (GI) tract is the most exposed to proteinases. Proteolytic activity must thus be tightly regulated in the face of diverse environmental challenges, because unrestrained or excessive proteolysis leads to pathological GI conditions. The protease-activated receptor-2 (PAR-2) is expressed in numerous cell types within the GI tract, suggesting both multiple functions and numerous modes of receptor activation. Although best known as a pancreatic digestive enzyme, trypsin has also been found in other tissues and various cancers. Of interest, trypsin and PAR-2 act together in an autocrine loop that promotes proliferation, invasion and metastasis in neoplasia through various mechanisms. Trypsin and PAR-2 seem to act both directly and indirectly through activation of other proteinase cascades, including metalloproteinases. PAR-2 activation can participate in inflammatory reactions, be protective to mucosal surfaces, send or inhibit nociceptive messages, modify gut motility or secretory functions, and stimulate cell proliferation and motility. Several studies point to a role for the PARs in disease processes of the GI tract and pancreas ranging from inflammatory bowel disease, symptoms associated with irritable bowel syndrome, pain in pancreatitis, development of colon and other GI cancers, and even infectious colitis. Proteinases should not only be considered from the traditional view as digestive or degradative enzymes in the gut, but additionally as signalling molecules that actively participate in the spectrum of physiology and diseased states of the GI tract.

A small interfering RNA targeting proteinase-activated receptor-2 is effective in suppression of tumor growth in a Panc1 xenograft model

Proteinase-activated receptor-2 (PAR-2), which is a G protein-coupled receptor, is activated in inflammatory processes and cell proliferation. We previously demonstrated that an anti-PAR-2 antibody suppresses proliferation of human pancreatic cells in vitro. However, there have been no studies of PAR-2 signaling pathways in vivo. The aim of this study was to determine whether blockade of PAR-2 by RNA interference influences pancreatic tumor growth. We originally constructed small interfering RNAs (siRNAs) targeting human PAR-2, and performed cell proliferation assays of Panc1 human pancreatic cancer cell line with these siRNAs. Intratumoral treatment with these PAR-2 siRNAs and atelocollagen was also performed in a xenograft model with nude mice and Panc1 cells. siRNAs against human PAR-2 inhibited proliferation of Panc1 cells, whereas control scramble siRNAs had no effect on proliferation. The PAR-2 siRNAs dramatically suppressed tumor growth in the xenograft model. PAR-2-specific siRNA inhibited growth of human pancreatic cancer cells both in vitro and in vivo. Blockade of PAR-2 signaling by siRNA may be a novel strategy to treat pancreatic cancer.

Protease-activated receptor-2 (PAR-2) in cervical cancer proliferation

OBJECTIVE

Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor that is cleaved and activated by trypsin and tryptase. There is evidence that PAR-2 contributes to tumor progression in stomach, colon, pancreas, prostate and breast cancer patients. However, the role of PAR-2 in cervical cancer is still unknown. The aim of this work was to study the PAR-2 expression in cervical cancer tissues and the effect of PAR-2 activation on cervical cancer proliferation.

METHODS

Immunohistochemistry was used to analyze PAR-2 expression in fixed paraffin-embedded tumor tissue from 16 patients with invasive cervical cancer. HPV types were identified by PCR. PAR-2 expression in UISO-SQC-1, HeLa, SiHa, CasKi and C-33 A cervical cancer cell lines was evaluated by flow cytometry. Trypsin was detected by Western blot. Tumor proliferation in response to trypsin or agonist peptide was evaluated by the MTT method.

RESULTS

A strong correlation between trypsin and PAR-2 expression in five cervical cancer cell lines, in association with proliferative growth in the presence of trypsin or agonist peptide, was found. All tumors from cervical cancer patients expressed PAR-2 (immunoreactive score was higher in poorly differentiated tumors).

CONCLUSIONS

Results suggest that trypsin and PAR-2 are involved in cervical cancer cell proliferation.

New developments in the relationship between protease activated recerptor-2 and alimentary system diseases

Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor, and its special molecule structure and activation way are similar to other protease-activated receptors. PAR-2 is widely distributed in alimentary system and series of effects are produced when it is activated by certain proteases. For example, PAR-2 exerts gastric mucosal cytoprotective effect, influences the secretion of digestive glands and movement of gastrointestinal tract, participates in the development of pancreatitis, and associates closely with malignant tumors in alimentary system. More and more researches are now focusing on the relationship between PAR-2 and alimentary system diseases.

Potential physiological and pathophysiological roles for protease-activated receptor-2 in the kidney (Review Article)

The protease-activated receptor-2 (PAR-2), the second of four members of a unique subfamily of G-protein coupled receptors, is abundantly expressed in the kidney. In a similar manner to other PAR cleavage of its extracellular N-terminus exposes a tethered ligand, SLIGKV in humans, which acts as an intramolecular ligand to activate itself. In the kidney, PAR-2 expression has been variably reported in collecting duct cells, mesangial cells, interstitial fibroblasts, vascular endothelial cells, vascular smooth muscle cells and proximal tubular cells. Despite this renal expression data, the function of PAR-2 in the kidney remains unknown. More than 15 different mammalian serine proteases have been shown to activate PAR-2 in an in vitro setting, but it is still unclear which of these are physiologically relevant activators of PAR-2 in specific tissues. Their identification could provide novel therapeutic targets. PAR-2 activates a number of down-stream signalling molecules that include protein kinase C, extracellular signal regulated kinase and nuclear factor kappa-B. Proteases that can activate PAR-2 are generated and released from cells during injury, inflammation and malignancy and can thus signal to cells under these conditions. Potential physiological and pathophysiological roles for PAR-2 in the kidney include the regulation of inflammation, blood flow, and ion transport and tissue protection, repair and fibrosis. In this review the potential roles of PAR-2 in the kidney are highlighted and discussed.

Trypsin in colorectal cancer: molecular biological mechanisms of proliferation, invasion, and metastasis

Trypsin is involved in colorectal carcinogenesis and promotes proliferation, invasion, and metastasis. Although a well-known pancreatic digestive enzyme, trypsin has also been found in other tissues and various cancers, most importantly of the colorectum. Moreover, colorectal cancers with trypsin expression have a poor prognosis and shorter disease-free survival. Biological understanding of how trypsin causes cancer progression is emerging. It seems to act both directly and indirectly through a 'proteinase-antiproteinase-system', and by activation of other proteinase cascades. Invasion of the basal membrane by cancer cells may be promoted directly by trypsin digestion of type I collagen. Trypsin activates, and is co-expressed with matrix metalloproteinases (MMPs), which are known to facilitate invasion and metastasis. MMP-2, MMP-7, and MMP-9 are co-expressed together with trypsin and seem to be of particular importance in proliferation, progression, and invasion. MMPs may play a role in both conversion from adenoma to carcinoma, and in the initiation of invasion and metastasis. Co-segregation of trypsin and MMPs within the tumour environment is important for the activation of MMPs, and may explain the deleterious effect of trypsin on prognosis in colorectal cancer. Trypsin and proteinase-activated receptor 2 (PAR-2) act together in an autocrine loop that promotes proliferation, invasion, and metastasis through various mechanisms, of which prostaglandin synthesis is important. Stimulated by trypsin, both MMP and PAR-2 may activate the mitogenic MAPK-ERK pathway through activation of the epidermal growth factor receptor. Experimental trypsin inhibition is feasible but not very effective, and trypsin as a target for clinical therapy is unlikely to be successful owing to its universal distribution. However, as the pathways of trypsin and co-activated protein cascades emerge, biological understanding of colorectal carcinogenesis will be further illuminated and may pave the way for prognosticators, predictors, and novel targets of therapy.

Biochemistry and clinical role of trypsinogens and pancreatic secretory trypsin inhibitor

Trypsinogens and PSTI/TATI/SPINK1 are expressed, usually together, at high levels by the pancreas but also by many other normal and malignant tissues. The present review describes studies on the expression and putative functions of trypsinogens and PSTI/TATI/SPINK1 in the human body. The clinical aspects are discussed, including the correlations between expression of trypsinogens and PSTI/TATI/SPINK1 in tissues, serum, and urine of patients with pancreatitis or cancer and clinicopathological characteristics, i.e., the roles of trypsinogens and PSTI/TATI/SPINK1 in spontaneous and hereditary pancreatitis, tumor progression, and prognosis.

Protease-activated receptor-2 regulates vascular endothelial growth factor expression in MDA-MB-231 cells via MAPK pathways

Protease-activated receptor 2 (PAR2) is a G-protein coupled receptor that is cleaved and activated by serine proteases including the coagulation protease factor VIIa (FVIIa). There is evidence that PAR2 function contributes to angiogenesis, but the mechanisms involved are poorly defined. Here we show that PAR2 activation in human breast cancer cells leads to the upregulation of vascular endothelial growth factor (VEGF). Activation of PAR2 with agonist peptide (AP), trypsin or FVIIa results in a robust increase of VEGF message and protein. Incubation of cells with PAR1-AP, PAR3-AP, PAR4-AP, or thrombin has only a modest effect on VEGF production. Cleavage blocking antibodies show that FVIIa-mediated VEGF production is PAR2 mediated. Mitogen-activated protein kinase (MAPK) pathway inhibitors U0126 and SB203580 inhibit PAR2-mediated VEGF production. Incubation of cells with PAR2-AP leads to significant extracellular regulated kinase1/2 (ERK1/2) and p38 MAPK phosphorylation and activation. Collectively, these data suggest that PAR2 signaling through MAPK pathways leads to the production of proangiogenic VEGF in breast cancer cells.

Role of pancreatic trypsin in chronic esophagitis induced by gastroduodenal reflux in rats

BACKGROUND

Reflux of the duodenal contents with gastric acid has been reported to contribute to the development of esophageal mucosal damage and inflammation. Recent studies show that pancreatic trypsin can stimulate the production of inflammatory mediators, including chemokines and prostaglandins from human esophageal epithelial cells in vitro. The aim of the present study was to investigate the role of pancreatic trypsin in the pathogenesis of chronic esophageal inflammation induced by gastroduodenal reflux in rats.

METHODS

Esophagogastroduodenal anastomosis was carried out in male Wistar rats by anastomosing the jejunum to the gastroesophageal junction under diethyl ether inhalation anesthesia. The animals undergoing surgery were treated with the control diet, rabeprazole sodium, nizatidine, ecabet sodium, camostat mesilate (CMM), ONO-1714, a specific inducible nitric oxide synthase (iNOS) inhibitor, or meloxicam, a selective cyclooxygenase-2 (COX-2) inhibitor. Esophageal injury was evaluated by macroscopic and microscopic findings, and mRNA expression for CINC-1, COX-2, and iNOS was determined by real-time polymerase chain reaction (PCR). Trypsin activity within the esophageal lumen was measured 2 weeks after surgery, and the expression of protease-activated receptor (PAR)-1 and -2 was confirmed by reverse transcription (RT)-PCR.

RESULTS

At 8 weeks after surgery, gastroduodenal reflux induced esophageal erosions and ulcer formation as well as marked thickening of the esophageal wall. Histological study showed an increase of thickness of the esophageal mucosa, hyperplasia of the epidermis and basal cells, ulcer formation, and marked infiltration of inflammatory cells. The macroscopic ulcer score and histological ulcer length were significantly reduced by treatment with rabeprazole or CMM but not by nizatidine or ecabet sodium, compared with each control. Rabeprazole, nizatidine, or ecabet sodium did not affect the severity of mucosal hyperplastic scores or histological parameters in esophagitis. In contrast, the CMM group showed a significant decrease in the mucosal hyperplastic and inflammatory scores. The enhanced expression of CINC-1, COX-2, and iNOS mRNA in the control group was also markedly inhibited in the CMM-treated group. ONO-1714 or meloxicam treatment significantly reduced the macroscopic scores of ulcer and hyperplasia. The trypsin activity in the esophageal lumen was significantly increased in the control diet group, and this increase was significantly inhibited in the CMM-treated group. The expression of PAR-1 and -2 mRNA was confirmed in rat esophageal epithelium.

CONCLUSIONS

With this model, we have demonstrated that CMM significantly reduces inflammation and hyperplasia in the esophageal mucosa. These results indicate that trypsin, which is primarily inhibited by CMM, plays an important role in the mucosal damage induced by gastroduodenal reflux and that it can be a therapeutic target in patients with gastroduodenal reflux esophagitis.

Potent pruritogenic action of tryptase mediated by PAR-2 receptor and its involvement in anti-pruritic effect of nafamostat mesilate in mice

The pruritogenic potency of tryptase and its involvement in anti-pruritic effect of intravenous nafamostat mesilate (NFM) were studied in mice. An intradermal injection of tryptase (0.05-1 ng/site) elicited scratching in ICR mice, while chymase was without effects at doses of 0.05-50 ng/site. The dose-response curve of tryptase action was bell-shaped and the effect peaked at 0.1 ng/site (approximately 0.7 fmol/site). NFM (10 mg/kg) inhibited scratching induced by tryptase but not by histamine and serotonin. NFM (1-10 mg/kg) produced the dose-dependent inhibition of scratching induced by intradermal compound 48/80 (10 microg/site). The inhibition by NFM (10 mg/kg) was abolished in mast cell-deficient (WBB6F1 W/W(V)) mice, but not in wild-type (WBB6F1 +/+) mice. NFM (10 mg/kg) suppressed tryptase activity in the mouse skin. Proteinase-activated receptor-2 (PAR-2) neutralizing antibody (0.1 and 1 microg/site) and the PAR-2 antagonist FSLLRY (10 and 100 microg/site) inhibited scratching induced by tryptase (0.1 ng/site) and compound 48/80 (10 microg/site). These results suggest that mast cell tryptase elicits itch through PAR-2 receptor and that NFM inhibits itch-associated responses mainly through the inhibition of mast cell tryptase.