Production of trypsins by human gastric cancer cells correlates with their malignant phenotype

Changes in Protease-Activated Receptor and Trypsin-1 Expression Are Involved in the Therapeutic Effect of Mg2+ Supplementation in Type 2 Diabetes-Induced Gastric Injury in Male Adult Rats

Purpose

Gastric inflammation is common and usually severe in patients with type 2 diabetes mellitus (T2DM). Evidence suggests protease-activated receptors (PARs) are a link between inflammation and gastrointestinal dysfunction. Given that magnesium (Mg²⁺) deficiency is a highly prevalent condition in T2DM patients, we assessed the therapeutic role of Mg²⁺ on the factors involved in gastric inflammation in T2DM.

Methods

A rat model of T2DM gastropathy was established using a long-term high-fat diet + a low dose of streptozocin. Twenty-four rats were divided into control, T2DM , T2DM + insulin (positive control), and T2DM + Mg²⁺ groups. At the end of 2-month therapies, changes in the expression of gastric trypsin-1, PAR1, PAR2, PAR3, PI3K/Akt, and COX-2 proteins were measured by western blot. Hematoxylin and eosin and Masson's trichrome staining were used to detect gastric mucosal injury and fibrosis.

Results

The expression of trypsin-1, PAR1, PAR2, PAR3, and COX-2 increased in diabetes, and Mg²⁺/insulin treatment strongly decreased their expression. The PI3K/p-Akt significantly decreased in T2DM, and treatment with Mg²⁺/insulin improved PI3K in T2DM rats. Staining of the gastric antrum tissue of the insulin/Mg²⁺-treated T2DM rats showed a significantly minimal mucosal and fibrotic injury compared with those of rats from the T2DM group.

Conclusion

Mg²⁺ supplement, comparable to insulin, via decreasing PARs expression, mitigating COX-2 activity, and decreasing collagen deposition could exert a potent gastroprotective effect against inflammation, ulcer, and fibrotic development in T2DM patients.

Tumor-associated trypsin inhibitor (TATI) and tumor-associated trypsin-2 (TAT-2) predict outcomes in gastric cancer

Introduction: Tumor-associated trypsin inhibitor (TATI) limits serine proteases, promotes carcinogenesis in several cancers and functions as an acute-phase reactant. Tumor-associated trypsin-2 (TAT-2), a proteolytic target enzyme for TATI, can enhance invasion by promoting extracellular matrix degradation. Here, we aimed to study serum TATI and TAT-2 levels, including the TAT-2/TATI ratio, as prognostic and diagnostic biomarkers in gastric cancer. We compared the results with the plasma level of C-reactive protein (CRP).Material and Methods: We selected 240 individuals operated on for gastric adenocarcinoma at the Helsinki University Hospital, Finland, between 2000 and 2009. We determined the preoperative serum TAT-2, TATI and plasma CRP levels using time-resolved immunofluorometric assays using monoclonal antibodies.Results: The medium serum TAT-2 level was higher among gastric cancer patients [8.68 ng/ml; interquartile range (IQR) 5.93-13.2] than among benign controls (median 5.41 ng/ml; IQR 4.12-11.8; p = .005). Five-year survival among patients with a high serum TAT-2 was 22.9% [95% confidence interval (CI) 11.7-34.1], compared to 52.2% (95% CI 44.6-59.8; p < .001) among those with a low level. The five-year survival among patients with a high serum TATI was 30.6% (95% CI 20.4-40.8), compared to 52.9% (95% CI 44.7-61.1; p < .001) among those with a low level. The serum TATI level remained significant in the multivariable survival analysis (hazard ratio 2.01; 95% CI 1.32-3.07). An elevated plasma CRP level associated with a high serum TATI level (p = .037).Conclusions: This study shows for the first time that a high serum TAT-2 may function as a prognostic biomarker in gastric cancer and that TAT-2 levels may be elevated compared to controls. Additionally, we show that the prognosis is worse among gastric cancer patients with a high serum TATI. These biomarkers serve as prognostic factors particularly among patients with a metastatic or a locally advanced disease.

The significance of scirrhous gastric cancer cell lines: the molecular characterization using cell lines and mouse models

Scirrhous gastric cancer (SGC) exhibits aggressiveness of the rapid infiltrating tumor cells with abundant fibroblasts. Experimental studies using SGC cell lines have obtained useful information about this cancer. Our literature search divulged a total of 18 SGC cell lines; two cell lines were established from primary SGC and the other lines were established from a metastatic lesion of SGC. Fibroblast growth factor receptor 2 (FGFR2) and transforming growth factor-beta receptor (TβR) are linked to the rapid development of SGC. Cross-talk between the cancer cells and cancer-associated fibroblasts (CAFs) has been shown to contribute to the progression of SGC. Chemokine (C-X-C motif) receptor 1 (CXCR1) from SGC cells might be associated with the abundant CAFs in cancer microenvironments. The in vivo models established using SGC cell lines are expected to serve as a useful tool for the development of drugs such as FGFR2 inhibitors, TβR inhibitors, and CXCR1 inhibitors, which might be promising as SGC treatments. However, the number of available SGC cell lines is insufficient for the clarification of the entire biologic behavior of SGC. Since the mechanisms responsible for the characteristic aggressiveness of SGC are not fully elucidated, the establishment of new SGC cell lines could help clarify the biological behavior of SGC and contribute to its treatment.

Antitumor Effects of Systemic DNAse I and Proteases in an In Vivo Model

Background. Cell-free DNA circulates in cancer patients and induces in vivo cell transformation and cancer progression in susceptible cells. Based on this, we hypothesized that depletion of circulating DNA with DNAse I and a protease mix could have antitumor effects. Study design. The study aimed to demonstrate that DNAse I and a protease mix can degrade in vitro DNA and proteins from the serum of healthy individuals and cancer patients, and in vivo in serum of Wistar rats,. Moreover, the antitumor effect of the systemically administered enzyme mix treatmentwas evaluated in nude mice subcutaneously grafted with the human colon cancer cell line SW480. Results. The serum DNA of cancer patients or healthy individuals was almost completely degraded in vitro by the enzymatic treatment, but no degradation was found with the enzymes given separately. The intravenous administration of the enzymes led to significant decreases in DNA and proteins from rat serum. No antitumor effect was observed in immunodeficient mice treated with the enzymes given separately. In contrast, the animals that received both enzymes exhibited a marked growth inhibition of tumors, 40% of them having pathological complete response. Conclusion. This study demonstrated that systemic treatment with DNAse I and a protease mix in rats decreases DNA and proteins from serum and that this treatment has antitumor effects. Our results support the hypothesis that circulating DNA could have a role in tumor progression, which can be offset by depleting it. Further studies are needed to prove this concept.

Investigate the binding of catechins to trypsin using docking and molecular dynamics simulation

To explore the inhibitory mechanism of catechins for digestive enzymes, we investigated the binding mode of catechins to a typical digestive enzyme-trypsin and analyzed the structure-activity relationship of catechins, using an integration of molecular docking, molecular dynamics simulation and binding free energy calculation. We found that catechins with different structures bound to a conservative pocket S1 of trypsin, which is comprised of residues 189–195, 214–220 and 225–228. In the trypsin-catechin complexes, Asp189 by forming strong hydrogen bonding, and Gln192, Trp215 and Gly216 through hydrophobic interactions, all significantly contribute to the binding of catechins. The number and the position of hydroxyl and aromatic groups, the structure of stereoisomers, and the orientation of catechins in the binding pocket S1 of trypsin all affect the binding affinity. The binding affinity is in the order of Epigallocatechin gallate (EGCG) > Epicatechin gallate (ECG) > Epicatechin (EC) > Epigallocatechin (EGC), and 2R-3R EGCG shows the strongest binding affinity out of other stereoisomers. Meanwhile, the synergic conformational changes of residues and catechins were also analyzed. These findings will be helpful in understanding the knowledge of interactions between catechins and trypsin and referable for the design of novel polyphenol based functional food and nutriceutical formulas.

Proteinase activated-receptors-associated signaling in the control of gastric cancer

Gastric cancer (GC) is the fourth most common cancer in the world and the second cause of cancer-related death. Gastric carcinogenesis is a multifactorial process, in which environmental and genetic factors interact to activate multiple intracellular signals thus leading to uncontrolled growth and survival of GC cells. One such a pathway is regulated by proteinase activated-receptors (PARs), seven transmembrane-spanning domain G protein-coupled receptors, which comprise four receptors (i.e., PAR-1, PAR-2, PAR-3, and PAR-4) activated by various proteases. Both PAR-1 and PAR-2 are over-expressed on GC cells and their activation triggers and/or amplifies intracellular pathways, which sustain gastric carcinogenesis. There is also evidence that expression of either PAR-1 or PAR-2 correlates with depth of wall invasion and metastatic dissemination and inversely with the overall survival of patients. Consistently, data emerging from experimental models of GC suggest that both these receptors can be important targets for therapeutic interventions in GC patients. In contrast, PAR-4 levels are down-regulated in GC and correlate inversely with the aggressiveness of GC, thus suggesting a negative role of this receptor in the control of GC. In this article we review the available data on the expression and role of PARs in GC and discuss whether manipulation of PAR-driven signals may be useful for interfering with GC cell behavior.

Specific Immunoassay Reveals Increased Serum Trypsinogen 3 in Acute Pancreatitis

BACKGROUND

Trypsinogen 3 is a minor trypsinogen isoform in the pancreas. In contrast with trypsin 1 and 2, trypsin 3 degrades pancreatic secretory trypsin inhibitor, which may lead to an excess of active trypsin and acute pancreatitis (AP). We developed an immunoassay for trypsinogen 3 and studied whether an assay of serum trypsinogen 3 is of clinical utility in the diagnosis of AP.

METHODS

Monoclonal antibodies were generated using recombinant human trypsinogen 3 as the antigen and used to establish a sandwich-type immunoassay. We analyzed serum trypsinogen 3 concentrations in 82 patients with AP and 63 patients with upper abdominal pain (controls). The reference interval was determined using serum samples from 172 apparently healthy individuals.

RESULTS

The measuring range of the trypsinogen 3 assay was 1.0–250 μg/L. Intra- and interassay CVs were &lt;11%, and cross-reactivity with other trypsinogen isoenzymes was &lt;0.1%. The median trypsinogen 3 concentration in serum from healthy individuals was &lt;1.0 μg/L, and the upper reference limit was 4.4 μg/L. We observed increased trypsinogen 3 concentrations in patients with mild (median 9.5 μg/L) and severe (15.0 μg/L) AP; in both groups, the concentrations were significantly higher than in controls (median &lt;1.0 μg/L) (P &lt; 0.0001). In ROC analysis, the area under the curve of trypsinogen 3 for separation between AP and controls was 0.90 (P &lt; 0.0001).

CONCLUSIONS

We established for the first time a specific immunoassay for trypsinogen 3 using monoclonal antibodies. Patients with AP were found to have increased serum concentrations of trypsinogen 3. The availability of this assay will be useful for studies of the clinical utility of trypsinogen 3.

Expression and biochemical characterization of nsP2 cysteine protease of Chikungunya virus

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes epidemic fever, rash and polyarthralgia in Africa and Asia. Although it is known since the 1950s, new epidemiological and clinical features reported during the recent outbreak in the Indian Ocean can be regarded as the emergence of a new disease. Numerous severe forms of the infection have been described that put emphasis on the lack of efficient antiviral therapy. Among the virus-encoded enzymes, nsP2 constitutes an attractive target for the development of antiviral drugs. It is a multifunctional protein of approximately 90 kDa with a helicase motif in the N-terminal portion of the protein while the papain-like protease activity resides in the C-terminal portion. The nsP2 proteinase is an essential enzyme whose proteolytic activity is critical for virus replication. In this work, a recombinant CHIKV nsP2pro and a C-terminally truncated variant were expressed in Escherichia coli and purified by metal-chelate chromatography. The enzymatic properties of the proteinase were then determined using specific synthetic fluorogenic substrates. This study constitutes the first characterization of a recombinant CHIKV nsP2 cysteine protease, which may be useful for future drug screening.

Serpin peptidase inhibitor clade A member 1 as a potential marker for malignancy in insulinomas

PURPOSE

The biological behavior of insulinomas cannot be predicted based on histopathologic criteria in which the diagnosis of malignancy is confirmed by the presence of metastases. In this study, microarray and quantitative real-time reverse transcription-PCR were applied to identify differentially expressed genes between malignant and nonmalignant insulinomas to search for useful biomarkers to recognize the metastatic potential of insulinomas.

EXPERIMENTAL DESIGN

Code Link human bioarrays were used to analyze differences in approximately 20,000 genes between six well-differentiated endocrine tumors of benign behavior compared with one well-differentiated endocrine carcinoma (WDEC) and three metastases of endocrine carcinomas (MEC). Quantitative real-time reverse transcription-PCR was used to validate differential expressions of five genes in a series of 35 sporadic insulinomas. Serpin peptidase inhibitor clade A member 1 (SERPINA1; alpha-1-antitrypsin) expression, identified as up-regulated in malignant insulinomas, was also evaluated by immunohistochemistry.

RESULTS

Analysis of microarray data resulted in 230 differentially expressed genes. Gene Ontology analysis identified serine-type endopeptidase activity and serine-type endopeptidase inhibitor activity as pathways presenting significant differential expression. Protease serine 2 and complement factor B (from serine-type endopeptidase activity pathway) were respectively confirmed as up-regulated in well-differentiated endocrine tumors of benign behavior (WDET) and in WDEC/MEC. Angiotensinogen and SERPINA1 (from serine-type endopeptidase inhibitor activity pathway) were confirmed as up-regulated in WDEC/MEC. SERPINA1 was shown to be expressed in 85.7% of malignant versus 14.3% of nonmalignant insulinomas by immunohistochemistry.

CONCLUSIONS

Our data are consistent to the possibility that SERPINA1 is a marker of malignancy in insulinomas. Given the widespread availability of antibody anti-alpha-1-antitrypsin in pathology services, SERPINA1 expression evaluation might be of clinical utility in recognizing patients more likely to develop an aggressive presentation.

Acidic extracellular pH increases calcium influx-triggered phospholipase D activity along with acidic sphingomyelinase activation to induce matrix metalloproteinase-9 expression in mouse metastatic melanoma

Acidic extracellular pH is a common feature of tumor tissues. We have reported that culturing cells at acidic pH (5.4-6.5) induced matrix metalloproteinase-9 expression through phospholipase D, extracellular signal regulated kinase 1/2 and p38 mitogen-activated protein kinases and nuclear factor-kappaB. Here, we show that acidic extracellular pH signaling involves both pathways of phospholipase D triggered by Ca2+ influx and acidic sphingomyelinase in mouse B16 melanoma cells. We found that BAPTA-AM [1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetrakis (acetoxymethyl) ester], a chelator of intracellular free calcium, and the voltage dependent Ca2+ channel blockers, mibefradil (for T-type) and nimodipine (for L-type), dose-dependently inhibited acidic extracellular pH-induced matrix metalloproteinase-9 expression. Intracellular free calcium concentration ([Ca2+]i) was transiently elevated by acidic extracellular pH, and this [Ca2+]i elevation was repressed by EGTA and the voltage dependent Ca2+ channel blockers but not by phospholipase C inhibitor, suggesting that acidic extracellular pH increased [Ca2+]i through voltage dependent Ca2+ channel. In contrast, SR33557, an L-type voltage dependent Ca2+ channel blocker and acidic sphingomyelinase inhibitor, attenuated matrix metalloproteinase-9 induction but did not affect calcium influx. We found that acidic sphingomyelinase activity was induced by acidic extracellular pH and that the specific acidic sphingomyelinase inhibitors (perhexiline and desipramine) and siRNA targeting aSMase/smpd1 could inhibit acidic extracellular pH-induced matrix metalloproteinase-9 expression. BAPTA-AM reduced acidic extracellular pH-induced phospholipase D but not acidic sphingomyelinase acitivity. The acidic sphingomyelinase inhibitors did not affect the phosphorylation of extracellular signal regulated kinase 1/2 and p38, but they suppressed nuclear factor-kappaB activity. These data suggest that the calcium influx-triggered phospholipase D and acidic sphingomyelinase pathways of acidic extracellular pH induced matrix metalloproteinase-9 expression, at least in part, through nuclear factor-kappaB activation.

Protease-activated receptor-2 activation in gastric cancer cells promotes epidermal growth factor receptor trans-activation and proliferation

Dysregulated epidermal growth factor receptor (EGFR) signaling is involved in gastric cancer (GC) cell growth. However, the mechanism that sustains EGFR signaling in GC remains unknown. Since protease-activated receptor-2 (PAR-2), a G protein-coupled receptor, has been shown to trans-activate EGFR in several cell types, we examined the role of PAR-2 in GC. We show here that in vitro activation of PAR-2 enhances the growth of two GC cell lines, AGS and MKN28. In both these cell lines, PAR-2 trans-activated EGFR and inhibition of EGFR tyrosine kinase activity by AG1478 or specific EGFR siRNA completely prevented PAR-2-driven proliferation. Antibody blockade of EGF-like ligands to EGFR did not modify EGFR signaling or cell growth induced by PAR-2 activation. In contrast, PAR-2 promoted Src activation and interaction of this kinase with EGFR. In support of this, inhibition of Src kinase activity by PP1 or siRNA blocked PAR-2-induced EGFR signaling cascade and cell growth. Finally, PAR-2 was detectable in both normal and GC specimens, but its expression was more pronounced in GC than controls and correlated with activated EGFR. These data show that PAR-2 is overexpressed in GC and suggest a role of PAR-2 in EGFR trans-activation and cell growth.

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.

Binding of trypsin to fibrillar amyloid beta-protein

We have recently reported that fibrillar amyloid beta-protein (Abeta) inhibits the proteolytic activity of trypsin and high molecular weight bovine brain protease. We report here that trypsin binds to fibrillar Abeta (fAbeta) and the resulting complex of trypsin/fAbeta is sodium dodecyl sulfate (SDS)-stable. Electron microscopic analysis confirmed the binding of trypsin on the fibrils of both Abeta 1-40 and Abeta 1-42. SDS-polyacrylamide gel electrophoresis (PAGE) of fAbeta sample incubated in the presence of trypsin showed that major amount of trypsin was associated with fAbeta that did not enter the gel. The presence of trypsin in this protein complex was confirmed by Western blotting after its elution from the gel. Kinetic studies showed that the binding of trypsin to fibrillar Abeta was dependent on the degree of Abeta fibrillization and on the concentration of fAbeta. However, the trypsin binding to Abeta oligomers did not affect the fibril growth. The maximum binding (B(max)) of trypsin to fAbeta 1-40 and fAbeta 1-42 was 36 pmol and 40 pmol, and dissociation constant (K(d)) was 18.31 microM and 20 microM respectively. Similar to fAbeta, trypsin could also bind to fibrillar amylin. This binding was dependent on the concentration of fibrillar amylin. Under similar conditions, bovine serum albumin did not bind to fibrillar Abeta. These results suggest that fAbeta and fibrillar amylin have strong affinities for trypsin, and chelation of proteases by abnormal aggregated proteins may be a general mechanism for inflicting pathological conditions in various diseases.

Production of soluble matriptase by human cancer cell lines and cell surface activation of its zymogen by trypsin

The membrane-bound serine proteinase matriptase, which is often released from the plasma membrane of epithelial and carcinoma cells, has been implicated to play important roles in both physiological and pathological conditions. However, the regulatory mechanism of its activity is poorly understood. In the present study, we examined expression and activation state of soluble matriptase in 24 human cancer cell lines. Soluble matriptase was detected in the conditioned media from all of 5 colon and 4 breast carcinoma cell lines and 8 of 10 stomach carcinoma cell lines tested. Only two of five lung cancer cell lines released the matriptase protein into the culture media. Out of the five matriptase-negative cell lines, two cell lines expressed the matriptase mRNA. Among 24 cancer cell lines tested, 13 cell lines secreted trypsin in an active or latent form and all of them released matriptase. Most of the 24 cell lines released a latent, single-chain matriptase of 75 kDa as a major form, as well as low levels of complex forms of an activated two-chain enzyme with its specific inhibitor HAI-1. Thus, these soluble matriptases appeared to have little proteolytic activity. Treatment of stomach and colon cancer cell lines with epidermal growth factor stimulated the release of matripatase/HAI-1 complexes. In cancer cell lines secreting active trypsin, however, matriptase was released mostly as an inhibitor-free, two-chain active form. Trypsin seemed to activate the membrane-bound, latent matriptase on the cell surface. These results suggest that matriptase and trypsin cooperatively function for extracellular proteolysis.

Versican protects cells from oxidative stress-induced apoptosis

Oxidant injury plays a critical role in the degenerative changes that are characterized by a decline in parenchymal cell numbers and viability, and occur with aging and in the etiology of many diseases. The extracellular proteoglycan versican is widely distributed in the extracellular matrix surrounding the cells. This study examines whether versican plays a role in protecting cells from free radical-induced apoptosis. Stable expression of versican or its C-terminal domain significantly decreased H(2)O(2)-induced cellular apoptosis. Cells in adherent monolayer were more resistant to H(2)O(2)-induced apoptosis than cells cultured in suspension. While vigorous trypsinization caused integrin cleavage and rendered the cells more susceptible to H(2)O(2)-induced damages, expression of versican or its C-terminal domain enhanced cell attachment and expression of beta1 integrin and fibronectin. Enhanced cell-matrix interaction by addition of manganese (MnCl(2)) to cultures also significantly diminished H(2)O(2)-induced apoptosis. The results suggest that versican plays an important role in reducing oxidant injury through an enhancement of cell-matrix interaction.

Expression of tumor-associated trypsinogens (TAT-1 and TAT-2) in prostate cancer

BACKGROUND

Trypsinogens are pancreatic serine proteinases and expressed in several cancers as tumor-associated trypsinogens (TAT). Trypsin mediates activation of pro-uPA and pro-MMPs, thus promoting angiogenesis and tumor invasion. Recently, we described expression of TAT in the human male genital tract and now we studied TAT in relation to PSA in PCa.

METHODS

TAT expression was studied by immunohistochemistry, in situ hybridization, RT-PCR, DNA-sequencing and IFMA. LNCaP cells were used to study secretion of TAT and PSA after androgen stimulation.

RESULTS

Immunoreactive TAT was localized in all prostatic tumors (n = 109), lymph node (n = 16), and bone metastases (n = 17). Immunostaining intensity increased with higher Gleason's grade, whereas PSA immunostaining decreased significantly. PSA and TAT were not identically distributed in benign and malignant cells. Androgen stimulation of LNCaP cells decreased secretion of TAT and increased that of PSA. TAT mRNA was demonstrated in tissue sections and identified as TAT-1 and -2 by RT-PCR and DNA-sequencing.

CONCLUSIONS

Expression of TAT is better preserved than PSA in high-grade PCa. Expression of TAT and PSA is regulated by different mechanisms as demonstrated in tissue sections and in vitro. Locally produced TAT may act in a paracrine mode to promote angiogenesis and tumor invasion in PCa by both activating and degrading of other proteinases. Further studies on the role of TAT in invasive PCa and on the mechanisms involved in the regulation of TAT expression are warranted.

Acidic extracellular pH induces matrix metalloproteinase-9 expression in mouse metastatic melanoma cells through the phospholipase D-mitogen-activated protein kinase signaling

The extracellular pH (pHe) of tumor tissues is often acidic, which can induce the expression of several proteins. We previously showed that production of matrix metalloproteinase-9 (MMP-9) was induced by culturing cells at acidic pHe (5.4-6.5). Here we have investigated the signal transduction pathway by which acidic pHe induces MMP-9 expression. We found that acidic pHe (5.9) activated phospholipase D (PLD), and inhibition of PLD activity by 1-butanol and Myr-ARF6 suppressed the acidic pHe-induced MMP-9 expression. Exogenous PLD, but not phosphatidylinositol-specific PLC or PLA2, mimicked MMP-9 induction by acidic pHe. Western blot analysis revealed that acidic pHe increased the steady-state levels of phosphorylated extracellular signal-regulated kinases 1/2 and p38 and that the PLD inhibitors suppressed these increases. Using 5'-deletion mutant constructs of the MMP-9 promoter, we found that the acidic pHe-responsive region was located at nucleotide -670 to -531, a region containing the NF kappa B binding site. A mutation into the NF kappa B binding site reduced, but not completely, the acidic pHe-induced MMP-9 promoter activity, and NF kappa B activity was induced by acidic pHe. Pharmacological inhibitors specific for mitogen-activated protein kinase kinase 1/2 (PD098059) and p38 (SB203580) attenuated the acidic pHe-induced NF kappa B activity and MMP-9 expression. These data suggest that PLD, mitogen-activated protein kinases (extracellular signal-regulated kinases 1/2 and p38), and NF kappa B mediate the acidic pHe signaling to induce MMP-9 expression. A transcription factor(s) other than NF kappa B may also be involved in the MMP-9 expression.

Inactivation of protease-activated receptor-1 by proteolytic removal of the ligand region in vascular endothelial cells

Proteolysis plays an important role in inactivating protease-activated receptor-1 (PAR1). We aimed to determine the cleavage site(s) responsive for the proteolytic inactivation of PAR1 in human umbilical vein endothelial cells. Fura-2 fluorometry revealed that the preceding stimulation with trypsin abolished the subsequent [Ca(2+)](i) response to thrombin, while the responses to PAR1-activating peptides remained intact. On the other hand, thrombin had no effect on the subsequent response to trypsin. The immunostaining with antibodies against the residues 35-46 (SPAN12) and 51-64 (WEDE15) revealed the broad boundaries of cleavage. Trypsin removed both epitopes from the cell surface within 3 min, while thrombin removed the epitope of SPAN12. The longer incubation with thrombin removed the epitope of WEDE15. However, PAR1-activating peptides thereafter induced an attenuated but significant elevation of [Ca(2+)](i). Not only the receptor internalization as observed with a confocal microscope, but also an additional cleavage was thus suggested to contribute to the thrombin-induced removal of the epitope of WEDE15. The analyses of the PAR1 mutants identified three cleavage sites for trypsin; residues 41-42, 70-71 and 82-83. The cleavage at the latter two sites was suggested to dominate that at the former, and thus remove the ligand region (residues 42-47). The inactivation of PAR1 due to proteolytic removal of the ligand region may contribute not only to the inactivation of PAR1 by proteases such as trypsin, but also to the termination of the intracellular signaling initiated by thrombin in the vascular endothelial cells.

Expression of enteropeptidase in differentiated enterocytes, goblet cells, and the tumor cells in human duodenum

Enteropeptidase (EP) is a serine proteinase and activates trypsinogen to trypsin, thus playing an important role in food digestion. Nevertheless, the localization of EP is still controversial, likely due to a lack of studies using specific antibodies against EP. The aim of this study was to define cellular localization of EP in human duodenum and expression in tumor cells at the duodenal region. Immunohistochemical staining for resected tissues was performed with two antibodies against recombinant EP light and heavy chains, respectively. In situ hybridization was done with two RNA probes that include either the light or the heavy chain sequences of proEP, respectively. The two antibodies reacted with enterocytes, accentuated on the brush border, and goblet cells, with increasing intensity from the bottom of crypts to the top of villi. Paneth cells, neuroendocrine cells, Brunner's glands, lymphocytes, smooth muscle, or connective tissue did not react with the antibodies. The two RNA probes detected EP mRNA expression only in enterocytes and goblet cells. EP is produced in enterocytes and goblet cells, and the localization on the brush border of the cells is reasonable for the physiological activation of digestive enzymes. Interestingly, the antibodies reacted with tumor cells in duodenal polyps and adenocarcinoma at the duodenum but not in Brunner's gland adenoma. EP seems to be a marker of differentiated enterocytes and goblet cells, which suggests the existence of a common progenitor of these cells. Furthermore, EP may be a useful marker of tumor cells originating from these cells.

Characterisation of the progression of azaserine-induced rat pancreatic adenocarcinoma by proliferative cell nuclear antigen, basement membrane laminin and trypsinogen immunohistochemistry

The progression of azaserine-induced rat pancreatic adenocarcinoma (AC) was characterised using quantitative and semiquantitative immunohistochemistry for proliferating cell nuclear antigen (PCNA), basement membrane laminin (BML) and trypsinogen (TG). Samples were taken 5-20 months after initiation. High PCNA-labelling indices (PCNA LIs) were measured 5 months after the induction of atypical acinar cell nodules (AACNs), which decreased later and stagnated until a further decline in the month 10 adenomas. Then a second premalignant proliferative wave was observed (month 13) within the adenoma stage. Later, in month 20 differentiated ACs PCNA LIs fell to the host tissue level but were found highest in the month 20 anaplastic ACs indicating a switch to malignant proliferation. Month 20 invasive ACs showed a number of separate proliferative foci. In early AACNs, BML decreased and remained low till the local maximum in the month 13 adenoma. Invasive ACs did not express BML. Month 5 AACN and differentiated AC were TG deficient but anaplastic AC regained its TG expression. However invasive AC was again TG negative. These results are discussed in combination with our previous data on progressional changes of autophagic capacity and microvessel densities.

Association of trypsin expression with tumour progression and matrilysin expression in human colorectal cancer

Overexpression of the matrix serine protease (MSP) trypsin has been implicated in tumour growth, invasion, and metastasis. The objective of this study was to clarify the clinicopathological and prognostic significance of trypsin expression in colorectal cancer. This study analysed the association between immunohistochemically detected trypsin expression in colorectal cancer and clinicopathological characteristics, and investigated whether trypsin is a predictor of recurrence and/or survival. Trypsin immunoreactivity was more intense at the invasive front than in the superficial part of the tumour. Sections with immunostaining signals in more than 30% of carcinoma cells at the invasive front, which were observed in 48 cases (48%), were judged to be positive for trypsin. Trypsin positivity was significantly correlated with depth of invasion, lymphatic and venous invasion, lymph node and distant metastasis, advanced pathological tumour-node-metastasis (TNM) stage, and recurrence. Patients with trypsin-positive carcinoma had significantly shorter overall and disease-free survival periods than did those with trypsin-negative carcinoma. Trypsin retained its significant predictive value for overall and disease-free survival in multivariate analysis that included conventional clinicopathological factors. It is well known that trypsin activates matrilysin (matrix metalloproteinase-7), which plays an important role in colorectal cancer progression. Patients with concordant overexpression of trypsin and matrilysin at the invasive front, in which they were often co-localized, had the worst prognosis. Trypsinogen-1-transfected HCT116 colon cancer cells showed not only trypsin activity, but also active matrilysin activity and were more invasive in vitro than mock-transfected HCT116 cells. These results suggest that trypsin plays a key role in the progression of colorectal cancer. Detection of trypsin expression as well as matrilysin is useful for the prediction of recurrence in and poor prognosis of colorectal cancer patients.

MMP-9 activation by tumor trypsin-2 enhances in vivo invasion of human tongue carcinoma cells

Various human cancer cells express tumor-associated trypsinogen-2 (TAT-2), which can efficiently activate matrix metalloproteinases (MMPs) in vitro. MMP-2 and MMP-9 are particularly associated with the invasive malignant potential of several tumors. To investigate the role of TAT-2 in tumor invasion, we overexpressed TAT-2 in two malignant human squamous cell carcinoma cell lines of tongue and in non-malignant human papilloma virus transformed gingival keratinocytes. The TAT-2 overexpression significantly increased the levels of active MMP-9 in the most malignant cell line. TAT-2-transfected cells intravasated (invaded blood vessels) up to 60% more efficiently than did the control cells in an in vivo chick embryo chorioallantoic membrane invasion model. This increased intravasation was almost completely abolished by a specific tumor-associated trypsin inhibitor (TATI). These results indicate that TAT-2 has a role in the invasive growth of tumors, either alone or in cascade with gelatinases, especially by generating active MMP-9.

Reduction of in vivo tumor growth by MMI-166, a selective matrix metalloproteinase inhibitor, through inhibition of tumor angiogenesis in squamous cell carcinoma cell lines of head and neck

Matrix metalloproteinases (MMPs) have been implicated in tumor invasion, metastasis, and angiogenesis. We have recently shown that MMI-166, a new orally active MMP inhibitor specific for MMP-2 and -9, suppressed experimental metastasis of Lewis lung cancer, C-H1 human colon cancer, and pancreatic cancer without affecting tumor growth in vitro. In the present study, we determined whether oral administration of MMI-166 reduces tumor growth not only in such tumors but also in squamous cell carcinoma of head and neck (SCCHN). MMI-166 inhibited both activity of MMP-2 and -9 without affecting steady state levels of their mRNAs in SCCHN. Interestingly, protein levels of MMP-2 and -9 from the cultures were drastically diminished by culturing with MMI-166. This was also observed in xenografts of MMI-166-administered mice. In addition, daily oral administration of MMI-166 (100mg/kg) inhibited local tumor growth accompanied by the reduction of blood vessel density and Ki-67-positivity and increase in terminal deoxynucleotidyl transferase-mediated cUDP nick-end labeling (TUNEL)-positivity. These results suggested that orally administered MMI-166 reduced in vivo tumor growth of SCCHN through inhibition of angiogenesis and induction of apoptosis accompanied by the reduction of MMP productions and activities. Therefore, MMI-166 seems to be useful for tumor dormancy therapy of SCCHN.

Crystal structure reveals basis for the inhibitor resistance of human brain trypsin

Severe neurodegradative brain diseases, like Alzheimer, are tightly linked with proteolytic activity in the human brain. Proteinases expressed in the brain, such as human trypsin IV, are likely to be involved in the pathomechanism of these diseases. The observation of amyloid formed in the brain of transgenic mice expressing human trypsin IV supports this hypothesis. Human trypsin IV is also resistant towards all studied naturally occurring polypeptide inhibitors. It has been postulated that the substitution of Gly193 to arginine is responsible for this inhibitor resistance. Here we report the X-ray structure of human trypsin IV in complex with the inhibitor benzamidine at 1.7 A resolution. The overall fold of human trypsin IV is similar to human trypsin I, with a root-mean square deviation of only 0.5 A for all C(alpha) positions. The crystal structure reveals the orientation of the side-chain of Arg193, which occupies an extended conformation and fills the S2' subsite. An analysis of surface electrostatic potentials shows an unusually strong clustering of positive charges around the primary specificity pocket, to which the side-chain of Arg193 also contributes. These unique features of the crystal structure provide a structural basis for the enhanced inhibitor resistance, and enhanced substrate restriction, of human trypsin IV.

Induction of SPARC by VEGF in human vascular endothelial cells

SPARC/osteonectin/BM-40 is a matricellular protein that is thought to be involved in angiogenesis and endothelial barrier function. Previously, we have detected high levels of SPARC expression in endothelial cells (ECs) adjacent to carcinomas of kidney and tongue. Although SPARC-derived peptide showed an angiogenic effect, intact SPARC itself inhibited the mitogenic activity of vascular endothelial growth factor (VEGF) for ECs by the inhibiting phosphorylation of flt-1 (VEGF receptor 1) and subsequent ERK activation. Thus, the role of SPARC in tumor angiogenesis, stimulation or inhibition, is still unclear. To clarify the role of SPARC in tumor growth and progression, we determined the effect of VEGF on the expression of SPARC in human microvascular EC line, HMEC-1, and human umbilical vein ECs. VEGF increased the levels of SPARC protein and steady-state levels of SPARC mRNA in serum-starved HMEC-1 cells. Inhibitors (SB202190 and SB203580) of p38, a mitogen-activated protein (MAP) kinase, attenuated VEGF-stimulated SPARC production in ECs. Since intact SPARC inhibits phosphorylation ERK MAP kinase in VEGF signaling, it was suggested that SPARC plays a dual role in the VEGF functions, tumor angiogenesis, and extravasation of tumors mediated by the increased permeability of endothelial barrier function.

The levels of trypsinogen isoenzymes in ovarian tumour cyst fluids are associated with promatrix metalloproteinase-9 but not promatrix metalloproteinase-2 activation

Proteolysis mediated by matrix metalloproteinases (MMPs) and serine proteinases is associated with cancer invasion and metastasis. Activation of latent proMMPs, and especially the proforms of the type IV collagen degrading gelatinases A and B (proMMP-2 and proMMP-9), is thought to be a critical step in this process. We have recently found that human tumour-associated trypsin-2 is a potent activator of proMMP-9 and it also activates proMMP-2 in vitro. Trypsinogen, MMP-2, and MMP-9 are expressed in ovarian cancer. To elucidate the function of trypsin in vivo, we studied whether high concentrations of trypsinogen-1, trypsinogen-2, their alpha(1)-proteinase inhibitor (API) complexes, and tumour-associated trypsin inhibitor (TATI) are associated with proMMP-2 and proMMP-9 activation in ovarian tumour cyst fluids. Zymography and immunofluorometric analysis of 61 cyst fluids showed a significant association between high trypsin concentrations and the activation of MMP-9 (P = 0.003-0.05). In contrast, the trypsin concentrations were inversely associated with the activation of MMP-2 (P = 0.01-0.02). Immunohistochemical analysis of ovarian tumour tissue demonstrated expression of trypsinogen-2 and TATI in the secretory epithelium. MMP-2 was detected both in stromal and epithelial cells whereas MMP-9 was detected in neutrophils and macrophage-like cells in stromal and epithelial areas. These results suggest that trypsin may play a role in the regulation of the MMP-dependent proteolysis associated with invasion and metastasis of ovarian cancer.

Inostamycin, an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase, suppresses invasion ability by reducing productions of matrix metalloproteinase-2 and -9 and cell motility in HSC-4 tongue carcinoma cell line

Inostamycin is an inhibitor of cytidine 5'-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG): inositol transferase. It significantly reduced epidermal growth factor (EGF)-induced in vitro invasion of the tongue carcinoma cell line, HSC-4, through reconstituted basement membrane Matrigel. Since phosphatidylinositol (PI) 4,5-biphosphate is important for signal transduction through protein kinase C and actin reorganisation, we further examined the effect of inostamycin on production of two matrix metalloproteinases (MMPs), MMP-2 and -9, and on cell motility. Zymographic analysis showed that inostamycin suppressed pro-MMP-2 and pro-MMP-9 levels at a dose-dependent fashion, while MMP-2 activity was not significantly affected. By reverse transcription-polymerase chain reaction, it was found that inostamycin diminished steady state levels of MMP-2 and -9 but not membrane type 1-MMP mRNA expressions. Inostamycin partially blocked both EGF- and phorbol 12-myristate 13-acetate-stimulated pro-MMP-9 production. A cytoplasmic calcium chelator (BAPTA-AM) dramatically elevated pro- MMP-9 and slightly elevated pro-MMP-2 secretions. EGF-stimulated motility of HSC-4 cells was suppressed by inostamycin treatment along with reduction of actin cytoskeletal reorganisation, filopodia formation and cdc42 expression. These results suggested that inostamycin would be useful for an anti-invasive agent in tongue cancer.

Association of trypsin expression with recurrence and poor prognosis in human esophageal squamous cell carcinoma

BACKGROUND

Overexpression of the matrix serine proteinase (MSP) trypsin has been implicated in tumor growth, invasion, and metastasis. The objective of this study was to clarify the clinicopathologic and prognostic significance of trypsin expression in esophageal squamous cell carcinomas (SCC).

METHODS

Production of trypsin in tissue extracts was analyzed by immunoblotting and gelatin zymography. The authors analyzed the association between immunohistochemically detected trypsin expression in esophageal SCC and clinicopathologic characteristics, and they investigated whether trypsin is a predictor of recurrence and/or survival.

RESULTS

Overproduction and activation of trypsin was observed in 6 of 10 tumor extracts. The trypsin immunoreactivities at the invasive front were more intense than those at the superficial layer. Sections with immunostaining signals in greater than 30% of carcinoma cells at the invasive front, which were observed in 52 (52%) cases, were judged to be positive for trypsin. Trypsin positivity was significantly correlated with the depth of invasion (P < 0.0001), lymph node metastasis (P = 0.0048), advanced pTNM classification (P = 0.0006), recurrence (P = 0.0003), and recurrence within the first postoperative year (P = 0.0005). Patients with trypsin positive carcinoma had significantly shorter disease free and overall survival times than did those with trypsin negative carcinoma (P < 0.0001 and P < 0.0001, respectively). Trypsin retained its significant predictive value for disease free and overall survival in multivariate analysis that included conventional clinicopathologic factors (P = 0.0029 and P = 0.0006, respectively). Patients with concomitant overexpression of trypsin and matrilysin at the invasive front, in which they often were colocalized, had the worst prognosis.

CONCLUSIONS

The authors' results suggest that trypsin plays a key role in the progression of esophageal carcinoma. Detection of trypsin expression as well as matrilysin is useful for the prediction of recurrence and poor prognosis.

Down-regulation of trypsinogen-2 expression by chemically modified tetracyclines: association with reduced cancer cell migration

Many types of human tumor express trypsinogen-2, which may be a significant factor in the activation of pro-MMPs and the invasiveness of tumors. Prevention of trypsinogen-2 expression in cancer cells might be of benefit in cancer therapy. We describe here chemicals capable of down-regulating the expression of trypsinogen-2. Doxycycline (DOXY) and chemically modified tetracyclines (CMTs), previously known as inhibitors of the matrix metalloproteinase (MMP)-dependent proteinase cascade, down-regulated the mRNA and protein expression of trypsinogen-2 by COLO-205 human colon adenocarcinoma cells at therapeutically attainable concentrations (0. 1 to 1.0 microM). DOXY specifically inhibited the activation of pro-MMP-9 and cell migration induced by enteropeptidase, a specific activator of trypsinogen. Pro-MMP-9 activation and cell migration were also inhibited by tumor-associated trypsin inhibitor (TATI), which is a highly specific inhibitor of trypsin. CMT-3 as well as CMT-5 also inhibited cell migration, but an effect on the enteropeptidase-enhanced activation of pro-MMP-9 was not observed. Our results indicate that CMTs, DOXY and TATI inhibit cancer cell migration by down-regulating trypsinogen-2 expression or activity. Inhibition of trypsinogen-2 expression may represent a mechanism contributing to the ability of CMTs to suppress the pericellular proteolytic activity of some tumors.

Trypsin stimulates integrin alpha(5)beta(1)-dependent adhesion to fibronectin and proliferation of human gastric carcinoma cells through activation of proteinase-activated receptor-2

Trypsin is widely expressed in various non-pancreatic tissues at low levels and overexpressed in some types of human cancers. In the present study, we found that trypsin stimulates integrin-dependent adhesion and growth of MKN-1 human gastric carcinoma cells. MKN-1 cells expressed both proteinase-activated receptor-1 (PAR-1) and PAR-2, which are activated by thrombin and trypsin, respectively. Both trypsin and the PAR-2 ligand SLIGKV promoted integrin alpha(5)beta(1)-mediated adhesion of MKN-1 cells to fibronectin, and less effectively integrin alpha(v)beta(3)-mediated cell adhesion to vitronectin, but not that to type IV collagen or laminin-1 at all. Thrombin and the PAR-1 ligand SFLLRN promoted the cell adhesion to vitronectin more strongly than trypsin or the PAR-2 ligand, but not the cell adhesion to fibronectin at all. The cell adhesion-stimulating effect of the PAR-2 ligand was significantly reduced by the pre-treatment of cells with trypsin, indicating that the effect of trypsin is mediated by PAR-2 activation. The trypsin-stimulated cell adhesion to vitronectin, but not to fibronectin, was effectively inhibited by the G(i) protein blocker pertussis toxin, and both cell adhesions were completely inhibited by the Src kinase inhibitor herbimycin A. Furthermore, trypsin and the PAR-2 ligand stimulated growth of MKN-1 cells more strongly than thrombin or the PAR-1 ligand. These results show that trypsin regulates cellular adhesion and proliferation by inducing PAR-2/G protein signalings, and that the integrin alpha(5)beta(1)- and integrin alpha(v)beta(3)-dependent cell adhesions are regulated by different PAR/G protein signalings.

Proteases in the evaluation of pancreatic function and pancreatic disease

This paper reviews the role of pancreatic proteases (focusing upon trypsin, chymotrypsin and elastase) in the diagnosis and management of chronic pancreatic insufficiency (CPI), emphasizing advances over the last 5 years. Some important novel aspects of these enzymes in acute pancreatitis are also described, including their role in diagnosis and their interaction with cholecystokinin in the pathogenesis of the disease. The recent interest in these enzymes as agents promoting the spread of cancer in animals and human subjects is also described. A hierarchical approach has been taken to explore the advantages and limitations of tests in different source materials: serum, feces, duodenal aspirate, and non-invasive pancreatic function tests. The practical usefulness of fecal elastase-1 and of fecal chymotrypsin concentrations in diagnosis and management of CPI, respectively, is one of the major lessons to be learned from analysis of the recent literature, and forms the principal message of this review.

Stimulation of cellular growth and adhesion to fibronectin and vitronectin in culture and tumorigenicity in nude mice by overexpression of trypsinogen in human gastric cancer cells

It has previously been reported that the trypsinogen gene is expressed in various human cancers. To investigate the possible role of trypsin in tumor malignancy, trypsinogen-1 cDNA was introduced into the human gastric carcinoma cell line MKN-1. The overexpression of trypsinogen-1 in MKN-1 cells stimulated cellular growth and adhesion to fibronectin and vitronectin when the trypsinogen activator enterokinase was added into the culture. Enterokinase treatment of the conditioned medium of the MKN-1 transfectants partially converted the proforms of gelatinases B and A to their apparent active forms. When the MKN-1 transfectants expressing trypsinogen-1 were intraperitoneally transplanted into nude mice, the mice frequently produced tumors in the colon, spleen and liver. However, the mice implanted with control MKN-1 cells produced no tumors. These results strongly suggest that tumor-derived trypsin contributes to the disseminated growth of some types of cancer cells including gastric cancer.

Expression of trypsin by epithelial cells of various tissues, leukocytes, and neurons in human and mouse

It has long been believed that trypsin is normally synthesized only in the pancreas. In the present study, expression of trypsin in human and mouse nonpancreatic tissues was examined. Northern blot analysis of normal human tissues indicated that the trypsin gene is expressed at high levels in the pancreas and spleen and considerably in the small intestine. However, in situ hybridization and immunohistochemistry demonstrated that trypsin is widely expressed in epithelial cells of the skin, esophagus, stomach, small intestine, lung, kidney, liver, and extrahepatic bile duct, as well as splenic and neuronal cells. In the spleen, trypsin message was detected in macrophages, monocytes, and lymphocytes in the white pulp. In the brain, it was detected in the nerve cells of the hippocampus and cerebral cortex. Analysis by gelatin zymography confirmed the presence of a latent or an active form of trypsin in various normal mouse tissues. Reverse transcription-polymerase chain reaction analysis also confirmed the expression of trypsin genes in the spleen, liver, kidney, and brain of normal mice. Such a broad distribution of trypsin suggests its general roles in the maintenance of normal epithelial cell functions, the immune defense system, and the central nervous system.