Suppression of Tumorigenicity-14, encoding matriptase, is a critical suppressor of colitis and colitis-associated colon carcinogenesis

ST14 interacts with TMEFF1 and is a predictor of poor prognosis in ovarian cancer

TMEFF1 is a new protein involved in the physiological functions of the central nervous system, and we previously reported TMEFF1 can promote ovarian cancer. ST14 was determined to be involved in the processes of epidermal differentiation, epithelial cell integrity, and vascular endothelial cell migration, etc. The relationship between ST14 and TMEFF1 in the ovary remains unknown. In this study, we detected the expression of ST14 and TMEFF1 in 130 different ovarian cancer tissues through immunohistochemistry. We determined ST14 and TMEFF1 were highly expressed in ovarian cancer, indicating a higher degree of tumor malignancy and a worse prognosis. Tissues significantly expressing ST14 also highly expressed TMEFF1, and the expression of the two proteins was positively correlated. Consistently, immunofluorescence double staining demonstrated the co-localization of ST14 and TMEFF1 in the same region, and immunoprecipitation confirmed the interaction between ST14 and TMEFF1. TMEFF1 expression was also reduced after knocking down ST14 through Western blot. MTT, wound healing and Transwell assays results determined that knockdown of ST14 inhibited proliferation, migration and invasion of ovarian cancer cells in vitro, but the inhibitory effect was restored after adding TMEFF1 exogenous protein. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways analysis showed that ST14 and its related genes were enriched in the processes of epithelial formation, intercellular adhesion, protein localization, and mitosis regulation. We also clarified the kinase, microRNA, and transcription factor target networks and the impact of genetic mutations on prognosis. Overall, high expression of ST14 and TMEFF1 in ovarian cancer predicts higher tumor malignancy and a worse prognosis. ST14 and TMEFF1 co-localize and interact with each other in ovarian cancer. ST14 can regulate TMEFF1 expression to promote proliferation, migration and invasion of ovarian cancer cells. We speculate that the relationship between ST14 and TMEFF1 in ovarian cancer could become a potential target for anti-cancer therapy.

Early-onset tufting enteropathy in HAI-2-deficient mice is independent of matriptase-mediated cleavage of EpCAM

Congenital tufting enteropathy (CTE) is a life-threatening intestinal disorder resulting from loss-of-function mutations in EPCAM and SPINT2. Mice deficient in Spint2, encoding the protease inhibitor HAI-2, develop CTE-like intestinal failure associated with a progressive loss of the EpCAM protein, which is caused by unchecked activity of the serine protease matriptase (ST14). Here, we show that loss of HAI-2 leads to increased proteolytic processing of EpCAM. Elimination of the reported matriptase cleavage site strongly suppressed proteolytic processing of EpCAM in vitro and in vivo. Unexpectedly, expression of cleavage-resistant EpCAM failed to prevent intestinal failure and postnatal lethality in Spint2-deficient mice. In addition, genetic inactivation of intestinal matriptase (St14) counteracted the effect of Spint2 deficiency in mice expressing cleavage-resistant EpCAM, indicating that matriptase does not drive intestinal dysfunction by excessive proteolysis of EpCAM. Interestingly, mice expressing cleavage-resistant EpCAM developed late-onset intestinal defects and exhibited a shortened lifespan even in the presence of HAI-2, suggesting that EpCAM cleavage is indispensable for EpCAM function. Our findings provide new insights into the role of EpCAM and the etiology of the enteropathies driven by Spint2 deficiency.

Intestinal barrier functions in hematologic and oncologic diseases

The intestinal barrier is a complex structure that not only regulates the influx of luminal contents into the systemic circulation but is also involved in immune, microbial, and metabolic homeostasis. Evidence implicating disruption in intestinal barrier functions in the development of many systemic diseases, ranging from non-alcoholic steatohepatitis to autism, or systemic complications of intestinal disorders has increased rapidly in recent years, raising the possibility of the intestinal barrier as a potential target for therapeutic intervention to alter the course and mitigate the complications associated with these diseases. In addition to the disease process being associated with a breach in the intestinal barrier functions, patients with hematologic and oncologic diseases are particularly at high risks for the development of increased intestinal permeability, due to the frequent use of broad-spectrum antibiotics and chemoradiation. They also face a distinct challenge of being intermittently severely neutropenic due to treatment of the underlying conditions. In this review, we will discuss how hematologic and oncologic diseases are associated with disruption in the intestinal barrier and highlight the complications associated with an increase in the intestinal permeability. We will explore methods to modulate the complication. To provide a background for our discussion, we will first examine the structure and appraise the methods of evaluation of the intestinal barrier.

The serine protease matriptase inhibits migration and proliferation in multiple myeloma cells

BACKGROUND

Multiple myeloma (MM) is an incurable malignancy of plasma cells. The serine protease matriptase is frequently dysregulated in human carcinomas, which facilitates tumor progression and metastatic dissemination. The importance of matriptase in hematological malignancies is yet to be clarified. In this study, we aimed to characterize the role of matriptase in MM.

MATERIALS AND METHODS

mRNA expression of matriptase and its inhibitors hepatocyte growth factor activator inhibitor (HAI)-1 and HAI-2 was studied in primary MM cells from patient samples and human myeloma cell lines (HMCLs). We further investigated the effect of matriptase on migration and proliferation of myeloma cells in vitro. By use of the CoMMpass database, we assessed the clinical relevance of matriptase in MM patients.

RESULTS

Matriptase was expressed in 96% of patient samples and all HMCLs tested. Overexpression of matriptase in vitro reduced proliferation, and significantly decreased cytokine-induced migration. Conversely, matriptase knockdown significantly enhanced migration. Mechanistically, overexpression of matriptase inhibited activation of Src kinase.

CONCLUSIONS

Our findings may suggest a novel role of matriptase as a tumor suppressor in MM pathogenesis.

ENaC activation by proteases

Proteases are fundamental for a plethora of biological processes, including signalling and tissue remodelling, and dysregulated proteolytic activity can result in pathogenesis. In this review, we focus on a subclass of membrane‐bound and soluble proteases that are defined as channel‐activating proteases (CAPs), since they induce Na⁺ ion transport through an autocrine mechanism when co‐expressed with the highly amiloride‐sensitive epithelial sodium channel (ENaC) in Xenopus oocytes. These experiments first identified CAP1 (channel‐activating protease 1, prostasin) followed by CAP2 (channel‐activating protease 2, TMPRSS4) and CAP3 (channel‐activating protease 3, matriptase) as in vitro mediators of ENaC current. Since then, more serine‐, cysteine‐ and metalloproteases were confirmed as in vitro CAPs that potentially cleave and regulate ENaC, and thus this nomenclature was not further followed, but is accepted as functional term or alias. The precise mechanism of ENaC modulation by proteases has not been fully elucidated. Studies in organ‐specific protease knockout models revealed evidence for their role in increasing ENaC activity, although the proteases responsible for ENaC activation are yet to be identified. We summarize recent findings in animal models of these CAPs with respect to their implication in ENaC activation. We discuss the consequences of dysregulated CAPs underlying epithelial phenotypes in pathophysiological conditions, and the role of selected protease inhibitors. We believe that these proteases may present interesting therapeutic targets for diseases with aberrant sodium homoeostasis.

Posttranslational modifications of serine protease TMPRSS13 regulate zymogen activation, proteolytic activity, and cell surface localization

TMPRSS13, a member of the type II transmembrane serine protease (TTSP) family, harbors four N-linked glycosylation sites in its extracellular domain. Two of the glycosylated residues are located in the scavenger receptor cysteine-rich (SRCR) protein domain, while the remaining two sites are in the catalytic serine protease (SP) domain. In this study, we examined the role of N-linked glycosylation in the proteolytic activity, autoactivation, and cellular localization of TMPRSS13. Individual and combinatory site-directed mutagenesis of the glycosylated asparagine residues indicated that glycosylation of the SP domain is critical for TMPRSS13 autoactivation and catalytic activity toward one of its protein substrates, the prostasin zymogen. Additionally, SP domain glycosylation-deficient TMPRSS13 displayed impaired trafficking of TMPRSS13 to the cell surface, which correlated with increased retention in the endoplasmic reticulum. Importantly, we showed that N-linked glycosylation was a critical determinant for subsequent phosphorylation of endogenous TMPRSS13. Taken together, we conclude that glycosylation plays an important role in regulating TMPRSS13 activation and activity, phosphorylation, and cell surface localization.

Protein Composition and Biomedical Potential of the Skin Secretion of Hylarana erythraea (Schlegel, 1837) (Anura: Ranidae) from Langkawi Archipelago, Kedah, Peninsular Malaysia

The skin secretion of amphibians is known for its high content of bioactive compounds. These bioactive compounds are essential for the advancement of biomedical industries. Four wild green paddy frogs, Hylarana erythraea, were collected from various habitat types within the Langkawi Archipelago. These frogs' skin secretions were collected, extracted, and analysed for their protein compounds together with biomedical potentials using liquid chromatography-mass spectrometry (LC-MS). The total protein concentration of H. erythraea skin secretions was determined as 0.269 mg/mL. Based on the UniProt (Anura) database, we identified 29 proteins. These proteins were categorised as antimicrobial (AMP) (38%), followed by hormone (17%), enzyme (17%), unreviewed proteins (17%), structural proteins (7%), and regulatory proteins (4%). The AMPs identified were from the family of esculentin-1, esculentin-2, brevinin-1, and frenatin-4, while the hormones belonged to the cholecystokinin group. The enzymes detected were adenylate cyclase 9, the suppressor of tumorigenicity 14 protein homolog, and the HGF activator. The structural proteins belonged to toe pad keratin 2 and Krt5.7 proteins, while the single regulatory protein is CCR4-NOT transcription complex subunit 6-like. These proteins have a wide range of biomedical importance, such as wound healings, facilitate digestions, anti-tumours, and anti-cancer effect.

The Intestinal Microbiota and Colorectal Cancer

The intestinal microbiota, composed of a large population of microorganisms, is often considered a “forgotten organ” in human health and diseases. Increasing evidence indicates that dysbiosis of the intestinal microbiota is closely related to colorectal cancer (CRC). The roles for intestinal microorganisms that initiated and facilitated the CRC process are becoming increasingly clear. Hypothesis models have been proposed to illustrate the complex relationship between the intestinal microbiota and CRC. Recent studies have identified Streptococcus bovis, enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, Enterococcus faecalis, Escherichia coli, and Peptostreptococcus anaerobius as CRC candidate pathogens. In this review, we summarized the mechanisms involved in microbiota-related colorectal carcinogenesis, including inflammation, pathogenic bacteria, and their virulence factors, genotoxins, oxidative stress, bacterial metabolites, and biofilm. We also described the clinical values of intestinal microbiota and novel strategies for preventing and treating CRC.

Membrane-anchored serine proteases as regulators of epithelial function

Cleavage of proteins in the extracellular milieu, including hormones, growth factors and their receptors, ion channels, and various cell adhesion and extracellular matrix molecules, plays a key role in the regulation of cell behavior. Among more than 500 proteolytic enzymes encoded by mammalian genomes, membrane-anchored serine proteases (MASPs), which are expressed on the surface of epithelial cells of all major organs, are excellently suited to mediate signal transduction across the epithelia and are increasingly being recognized as important regulators of epithelial development, function, and disease [ 1-3]. In this minireview, we summarize current knowledge of the in vivo roles of MASPs in acquisition and maintenance of some of the defining functions of epithelial tissues, such as barrier formation, ion transport, and sensory perception.

Expression profiling revealed keratins and interleukins as potential biomarkers in squamous cell carcinoma of horn in Indian bullocks (Bos indicus)

Horn cancer is most prevalent in Bos indicus and poorly defined genetic landscape makes disease diagnosis and treatment difficult. In this study, RNA-Seq and data analysis using CLC Genomics Workbench was employed to identify biomarkers associated with horn cancer. As a result, a total of 149 genes were found significant differentially expressed in horn cancer samples compared to horn normal samples. The study revealed 'keratins' and 'interleukins' as apex groups of significant differentially expressed genes (DEGs). Functional analysis showed that the upregulated keratins support metastasis of tumor via cell proliferation, migration, and affecting cell stability, while downregulated interleukins along with other associated chemokine receptors deprive the immune response to tumor posing clear path for metastasis of horn cancer. Combi-action of both the group facilitates the tumor microenvironment to reproduce tumorigenesis. Analysis of pathways enriched in DEGs and exemplified protein-protein interaction network indicated actual role of DEGs in horn cancer at a fine level. Important effect of deregulated expression of keratin and interleukin genes in horn cancer enrolling their candidacy as potential biomarkers for horn cancer prognosis. This study appraises the possibility to mitigate horn cancer at fine resolution to extract attainable identification of prognostic molecular portraits.

Protease-activated receptor-2 accelerates intestinal tumor formation through activation of nuclear factor-κB signaling and tumor angiogenesis in ApcMin/+ mice

Hepatocyte growth factor activator inhibitor‐1 (HAI‐1), encoded by the SPINT1 gene, is a membrane‐bound protease inhibitor expressed on the surface of epithelial cells. Hepatocyte growth factor activator inhibitor‐1 regulates type II transmembrane serine proteases that activate protease‐activated receptor‐2 (PAR‐2). We previously reported that deletion of Spint1 in Apc^Min/+ mice resulted in accelerated formation of intestinal tumors, possibly through enhanced nuclear factor‐κB signaling. In this study, we examined the role of PAR‐2 in accelerating tumor formation in the Apc^Min/+ model in the presence or absence of Spint1. We observed that knockout of the F2rl1 gene, encoding PAR‐2, not only eliminated the enhanced formation of intestinal tumors caused by Spint1 deletion, but also reduced tumor formation in the presence of Spint1. Exacerbation of anemia and weight loss associated with HAI‐1 deficiency was also normalized by compound deficiency of PAR‐2. Mechanistically, signaling triggered by deregulated protease activities increased nuclear translocation of RelA/p65, vascular endothelial growth factor expression, and vascular density in Apc^Min/+‐induced intestinal tumors. These results suggest that serine proteases promote intestinal carcinogenesis through activation of PAR‐2, and that HAI‐1 plays a critical tumor suppressor role as an inhibitor of matriptase, kallikreins, and other PAR‐2 activating proteases.

Cell surface-anchored serine proteases in cancer progression and metastasis

Over the last two decades, a novel subgroup of serine proteases, the cell surface-anchored serine proteases, has emerged as an important component of the human degradome, and several members have garnered significant attention for their roles in cancer progression and metastasis. A large body of literature describes that cell surface-anchored serine proteases are deregulated in cancer and that they contribute to both tumor formation and metastasis through diverse molecular mechanisms. The loss of precise regulation of cell surface-anchored serine protease expression and/or catalytic activity may be contributing to the etiology of several cancer types. There is therefore a strong impetus to understand the events that lead to deregulation at the gene and protein levels, how these precipitate in various stages of tumorigenesis, and whether targeting of selected proteases can lead to novel cancer intervention strategies. This review summarizes current knowledge about cell surface-anchored serine proteases and their role in cancer based on biochemical characterization, cell culture-based studies, expression studies, and in vivo experiments. Efforts to develop inhibitors to target cell surface-anchored serine proteases in cancer therapy will also be summarized.

Matriptase drives early-onset intestinal failure in a mouse model of congenital tufting enteropathy

Syndromic congenital tufting enteropathy (CTE) is a life-threatening recessive human genetic disorder that is caused by mutations in SPINT2, encoding the protease inhibitor HAI-2, and is characterized by severe intestinal dysfunction. We recently reported the generation of a Spint2-deficient mouse model of CTE. Here, we show that the CTE-associated early-onset intestinal failure and lethality of Spint2-deficient mice is caused by unchecked activity of the serine protease matriptase. Macroscopic and histological defects observed in the absence of HAI-2, including villous atrophy, luminal bleeding, loss of mucin-producing goblet cells, loss of defined crypt architecture and the resulting acute inflammatory response in the large intestine, were all prevented by intestinal-specific inactivation of the St14 gene encoding matriptase. The CTE-associated loss of the cell junctional proteins EpCAM and claudin 7 was also prevented. As a result, inactivation of intestinal matriptase allowed Spint2-deficient mice to gain weight after birth and dramatically increased their lifespan. These data implicate matriptase as a causative agent in the development of CTE and may provide a new target for the treatment of CTE in individuals carrying SPINT2 mutations.This article has an associated 'The people behind the papers' interview.

Distinct Localization of Mature HGF from its Precursor Form in Developing and Repairing the Stomach

Hepatocyte growth factor (HGF) is secreted as an inactive single-chain HGF (scHGF); however, only proteolytically processed two-chain HGF (tcHGF) can activate the MET receptor. We investigated the localization of tcHGF and activated/phosphorylated MET (pMET) using a tcHGF-specific antibody. In day 16.5 mouse embryos, total HGF (scHGF + tcHGF) was mainly localized in smooth muscle cells close to, but separate from, MET-positive epithelial cells in endodermal organs, including the stomach. In the adult stomach, total HGF was localized in smooth muscle cells, and tcHGF was mainly localized in the glandular base region. Immunostaining for pMET and Lgr5-driven green fluorescent protein (GFP) indicated that pMET localization overlapped with Lgr5⁺ gastric stem cells. HGF promoted organoid formation similar to EGF, indicating the potential for HGF to promote the survival and growth of gastric stem cells. pMET and tcHGF localizations changed during regeneration following gastric injury. These results indicate that MET is constantly activated in gastric stem cells and that the localization of pMET differs from the primary localization of precursor HGF but has a close relationship to tcHGF. Our results suggest the importance of the microenvironmental generation of tcHGF in the regulation of development, regeneration, and stem cell behavior.

Inflammation-dependent overexpression of c-Myc enhances CRL4DCAF4 E3 ligase activity and promotes ubiquitination of ST7 in colitis-associated cancer

Inflammation is well known as an important driver of the initiation of colitis-associated cancer (CAC). Some cytokines, such as IL-6 and TNF-α can activate expression of the oncogene c-Myc (MYC) and regulate its downstream effects. Cullin-RING E3 Ligases (CRLs) are emerging as master regulators controlling tumorigenesis. Here, we demonstrate that two cullin genes, CUL4A and CUL4B, but not other members, are specifically overexpressed in CAC tumour samples and positively correlate with levels of the proinflammatory cytokines IL-1β and IL-6. In vitro experiments revealed that the transcription factor c-Myc can specifically activate the expression of CUL4A and CUL4B by binding to a conserved site (CACGTG) located in their promoters. Additionally, we found that both CUL4A and CUL4B can form an E3 complex with DNA damage-binding protein 1 (DDB1) and DDB1-CUL4-associated factor 4 (DCAF4). In vitro and in vivo ubiquitination analyses indicate that CRL4^DCAF4 E3 ligase specifically directs degradation of ST7 (suppression of tumorigenicity 7). Overexpression of c-Myc in human colon epithelial cells resulted in the accumulation of CUL4A, CUL4B and DCAF4, but degradation of ST7. In contrast, knockdown of c-Myc, CUL4A or CUL4B in the colon adenocarcinoma cell line HT29 caused accumulation of ST7 and inhibition of cell proliferation, colony formation ability and in vivo tumour growth. Collectively, our results provide in vitro and in vivo evidence that c-Myc regulates CRL4^DCAF4 E3 ligase activity to mediate ubiquitination of ST7, whose presence is physiologically essential for CAC tumorigenesis. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Membrane-Anchored Serine Proteases and Protease-Activated Receptor-2-Mediated Signaling: Co-Conspirators in Cancer Progression

Pericellular proteolysis provides a significant advantage to developing tumors through the ability to remodel the extracellular matrix, promote cell invasion and migration, and facilitate angiogenesis. Recent advances demonstrate that pericellular proteases can also communicate directly to cells by activation of a unique group of transmembrane G-protein-coupled receptors (GPCR) known as protease-activated receptors (PAR). In this review, we discuss the specific roles of one of four mammalian PARs, namely PAR-2, which is overexpressed in advanced stage tumors and is activated by trypsin-like serine proteases that are highly expressed or otherwise dysregulated in many cancers. We highlight recent insights into the ability of different protease agonists to bias PAR-2 signaling and the newly emerging evidence for an interplay between PAR-2 and membrane-anchored serine proteases, which may co-conspire to promote tumor progression and metastasis. Interfering with these pathways might provide unique opportunities for the development of new mechanism-based strategies for the treatment of advanced and metastatic cancers.

Intestinal epithelial Notch-1 protects from colorectal mucinous adenocarcinoma

Increasing evidence links Notch-1 signaling with the maintenance of intestinal architecture and homeostasis. Dysfunction in the common Notch-1 pathway transcription factor recombinant binding protein suppressor of hairless (RBP-J) is associated with loss of epithelial barrier integrity and aberrant conversion of proliferative crypt cells into goblet cells. Furthermore, we have recently discovered that epithelial Notch-1 is indispensable in bridging innate and adaptive immunity in the gut and is required for supporting protective epithelial pro-inflammatory responses. Yet, the epithelial specific function of Notch-1 in intestinal tumorigenesis remains unknown. We generated Villin-Cre/Notch-1^fl/fl (VN^-/-) mice that are selectively deficient in Notch-1 in intestinal epithelial cells. Intestinal epithelial Notch-1 preserved barrier function and integrity, whereas lack of epithelial Notch-1 induced goblet cell hyperplasia, spontaneous serrated lesions, multifocal low- and high-grade dysplasia and colonic mucinous neoplasms in mice. Over time, VN^-/- mice displayed high occurrence of colorectal mucinous adenocarcinomas, which correlated with increased levels of mitogenic, angiogenic and pro-tumorigenic gene expression. Finally, we found that the expression of Notch-1 is significantly reduced in human colorectal mucinous adenocarcinoma when compared to colorectal adenocarcinoma. Taken together, our findings reveal a novel and critical protective role for Notch-1 in controlling intestinal tumorigenesis.

Intestinal regulation of suppression of tumorigenicity 14 (ST14) and serine peptidase inhibitor, Kunitz type -1 (SPINT1) by transcription factor CDX2

The type II membrane-anchored serine protease, matriptase, encoded by suppression of tumorgenicity-14 (ST14) regulates the integrity of the intestinal epithelial barrier in concert with its inhibitor, HAI-1 encoded by serine peptidase inhibitor, Kunitz type -1 (SPINT1). The balance of the protease/inhibitor gene expression ratio is vital in preventing the oncogenic potential of matriptase. The intestinal cell lineage is regulated by a transcriptional regulatory network where the tumor suppressor, Caudal homeobox 2 (CDX2) is considered to be an intestinal master transcription factor. In this study, we show that CDX2 has a dual function in regulating both ST14 and SPINT1, gene expression in intestinal cells. We find that CDX2 is not required for the basal ST14 and SPINT1 gene expression; however changes in CDX2 expression affects the ST14/SPINT1 mRNA ratio. Exploring CDX2 ChIP-seq data from intestinal cell lines, we identified genomic CDX2-enriched enhancer elements for both ST14 and SPINT1, which regulate their corresponding gene promoter activity. We show that CDX2 displays both repressive and enhancing regulatory abilities in a cell specific manner. Together, these data reveal new insight into transcriptional mechanisms controlling the intestinal matriptase/inhibitor balance.

Mutant cytoskeletal and ECM peptides sensitive to the ST14 protease are associated with a worse outcome for glioblastoma multiforme

We previously identified a set of the most frequently mutated cytoskeleton- and extracellular matrix-related proteins (CECMPs) in numerous cancer datasets. In this report, we used a bioinformatics approach to assess the impact of amino acid (AA) substitutions on the sensitivity of CECMPs to the ST14 protease (matriptase I), a transmembrane serine protease previously implicated in cancer development. Results indicated that AA substitutions in glioblastoma multiforme (GBM) CECMPs are skewed toward increased resistance to the ST14 protease, in comparison to the wild-type peptide sequence. Furthermore, the protease resistant AA substitutions represent relatively high binding affinities to HLA class I proteins, when assessing the binding specificities using HLA class I alleles matched to the source of the mutant AA. Moreover, samples representing AA substitutions that increased protease sensitivity also represented reduced overall and disease-free survival periods for patients with glioblastoma. To assess tumor specimen immunogenicity, we identified T-cell receptor (TCR) V(D)J recombinations in GBM exome files. The overlap between ST14 protease sensitive mutant barcodes and the TCR V(D)J recombination read positive barcodes represented significantly reduced survival.

Microbiome, inflammation and colorectal cancer

Chronic inflammation is linked to the development of multiple cancers, including those of the colon. Inflammation in the gut induces carcinogenic mutagenesis and promotes colorectal cancer initiation. Additionally, myeloid and lymphoid cells infiltrate established tumors and propagate so called "tumor-elicited inflammation", which in turn favors cancer development by supporting the survival and proliferation of cancer cells. In addition to the interaction between cancer cells and tumor infiltrating immune cells, the gut also hosts trillions of bacteria and other microbes, whose roles in colorectal inflammation and cancer have only been appreciated in the past decade or so. Commensal and pathobiotic bacteria promote colorectal cancer development by exploiting tumor surface barrier defects following cancer initiation, by invading normal colonic tissue and inducing local inflammation, and by generating genotoxicity against colonic epithelial cells to accelerate their oncogenic transformation. On the other hand, a balanced population of microbiota is important for the prevention of colorectal cancer due to their roles in providing certain bacterial metabolites and inhibiting intestinal inflammation. In this review we summarize our current knowledge regarding the link between microbiota, inflammation, and colorectal cancer, and aim to delineate the mechanisms by which gut microbiome and inflammatory cytokines regulate colorectal tumorigenesis.

Gene signature based on degradome-related genes can predict distal metastasis in cervical cancer patients

Cervical cancer is one of the leading causes of death in women worldwide, which mainly affects developing countries. The patients who suffer a recurrence and/or progression disease have a higher risk of developing distal metastases. Proteases comprising the degradome given its ability to promote cell growth, migration, and invasion of tissues play an important role during tumor development and progression. In this study, we used high-density microarrays and quantitative reverse transcriptase polymerase chain reaction to evaluate the degradome profile and their inhibitors in 112 samples of patients diagnosed with locally advanced cervical cancer. Clinical follow-up was done during a period of 3 years. Using a correlation analysis between the response to treatment and the development of metastasis, we established a molecular signature comprising eight degradome-related genes (FAM111B, FAM111A, CFB, PSMB8, PSMB9, CASP7, PRSS16, and CD74) with the ability to discriminate patients at risk of distal metastases. In conclusion, present results show that molecular signature obtained from degradome genes can predict the possibility of metastasis in patients with locally advanced cervical cancer.

Type II transmembrane serine proteases as potential targets for cancer therapy

Carcinogenesis is accompanied by increased protein and activity levels of extracellular cell-surface proteases that are capable of modifying the tumor microenvironment by directly cleaving the extracellular matrix, as well as activating growth factors and proinflammatory mediators involved in proliferation and invasion of cancer cells, and recruitment of inflammatory cells. These complex processes ultimately potentiate neoplastic progression leading to local tumor cell invasion, entry into the vasculature, and metastasis to distal sites. Several members of the type II transmembrane serine protease (TTSP) family have been shown to play critical roles in cancer progression. In this review the knowledge collected over the past two decades about the molecular mechanisms underlying the pro-cancerous properties of selected TTSPs will be summarized. Furthermore, we will discuss how these insights may facilitate the translation into clinical settings in the future by specifically targeting TTSPs as part of novel cancer treatment regimens.

Matriptase zymogen supports epithelial development, homeostasis and regeneration

Background

Matriptase is a membrane serine protease essential for epithelial development, homeostasis, and regeneration, as well as a central orchestrator of pathogenic pericellular signaling in the context of inflammatory and proliferative diseases. Matriptase is an unusual protease in that its zymogen displays measurable enzymatic activity.

Results

Here, we used gain and loss of function genetics to investigate the possible biological functions of zymogen matriptase. Unexpectedly, transgenic mice mis-expressing a zymogen-locked version of matriptase in the epidermis displayed pathologies previously reported for transgenic mice mis-expressing wildtype epidermal matriptase. Equally surprising, mice engineered to express only zymogen-locked endogenous matriptase, unlike matriptase null mice, were viable, developed epithelial barrier function, and regenerated the injured epithelium. Compatible with these observations, wildtype and zymogen-locked matriptase were equipotent activators of PAR-2 inflammatory signaling.

Conclusion

The study demonstrates that the matriptase zymogen is biologically active and is capable of executing developmental and homeostatic functions of the protease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12915-017-0384-4) contains supplementary material, which is available to authorized users.

Inflammatory cytokines down-regulate the barrier-protective prostasin-matriptase proteolytic cascade early in experimental colitis

Compromised gastrointestinal barrier function is strongly associated with the progressive and destructive pathologies of the two main forms of irritable bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD). Matriptase is a membrane-anchored serine protease encoded by suppression of tumorigenicity-14 (ST14) gene, which is critical for epithelial barrier development and homeostasis. Matriptase barrier-protective activity is linked with the glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin, which is a co-factor for matriptase zymogen activation. Here we show that mRNA and protein expression of both matriptase and prostasin are rapidly down-regulated in the initiating inflammatory phases of dextran sulfate sodium (DSS)-induced experimental colitis in mice, and, significantly, the loss of these proteases precedes the appearance of clinical symptoms, suggesting their loss may contribute to disease susceptibility. We used heterozygous St14 hypomorphic mice expressing a promoter-linked β-gal reporter to show that inflammatory colitis suppresses the activity of the St14 gene promoter. Studies in colonic T84 cell monolayers revealed that barrier disruption by the colitis-associated Th2-type cytokines, IL-4 and IL-13, down-regulates matriptase as well as prostasin through phosphorylation of the transcriptional regulator STAT6 and that inhibition of STAT6 with suberoylanilide hydroxamic acid (SAHA) restores protease expression and reverses cytokine-induced barrier dysfunction. Both matriptase and prostasin are significantly down-regulated in colonic tissues from human subjects with active ulcerative colitis or Crohn's disease, implicating the loss of this barrier-protective protease pathway in the pathogenesis of irritable bowel disease.

Human airway trypsin-like protease, a serine protease involved in respiratory diseases

More than 2% of all human genes are coding for a complex system of more than 700 proteases and protease inhibitors. Among them, serine proteases play extraordinary, diverse functions in different physiological and pathological processes. The human airway trypsin-like protease (HAT), also referred to as TMPRSS11D and serine 11D, belongs to the emerging family of cell surface proteolytic enzymes, the type II transmembrane serine proteases (TTSPs). Through the cleavage of its four major identified substrates, HAT triggers specific responses, notably in epithelial cells, within the pericellular and extracellular environment, including notably inflammatory cytokine production, inflammatory cell recruitment, or anticoagulant processes. This review summarizes the potential role of this recently described protease in mediating cell surface proteolytic events, to highlight the structural features, proteolytic activity, and regulation, including the expression profile of HAT, and discuss its possible roles in respiratory physiology and disease.

Matriptase-mediated cleavage of EpCAM destabilizes claudins and dysregulates intestinal epithelial homeostasis

Congenital tufting enteropathy (CTE) is a severe autosomal recessive human diarrheal disorder with characteristic intestinal epithelial dysplasia. CTE can be caused by mutations in genes encoding EpCAM, a putative adhesion molecule, and HAI-2, a cell surface protease inhibitor. A similar phenotype occurs in mice whose intestinal epithelial cells (IECs) fail to express the tight junction-associated protein claudin-7. EpCAM stabilizes claudin-7 in IECs, and HAI-2 regulates the cell surface serine protease matriptase, a known modifier of intestinal epithelial physiology. Therefore, we hypothesized that HAI-2, matriptase, EpCAM, and claudin-7 were functionally linked. Herein we have demonstrated that active matriptase cleaves EpCAM after Arg80 and that loss of HAI-2 in IECs led to unrestrained matriptase activity and efficient cleavage of EpCAM. Cleavage of EpCAM decreased its ability to associate with claudin-7 and targeted it for internalization and lysosomal degradation in conjunction with claudin-7. CTE-associated HAI-2 mutant proteins exhibited reduced ability to inhibit matriptase and also failed to efficiently stabilize claudin-7 in IECs. These results identify EpCAM as a substrate of matriptase and link HAI-2, matriptase, EpCAM, and claudin-7 in a functionally important pathway that causes disease when it is dysregulated.

The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction

Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.

Decreasing the ratio of matriptase/HAI‑1 by downregulation of matriptase as a potential adjuvant therapy in ovarian cancer

Tumor invasion and metastasis are complex biological processes. Matriptase and its endogenous inhibitor, hepatocyte growth factor activator inhibitor‑1 (HAI‑1) are involved in invasion and metastasis. To evaluate the ratio of matriptase/HAI‑1 and their potential therapeutic value in ovarian cancer, HO‑8910 human ovarian cancer cells and the homologous high‑metastatic HO‑8910PM cells were used as in vitro cellular models ovarian cancer. The invasive and metastatic abilities, and the expression of matriptase and HAI‑1 in these cells were detected using scratch assays, Transwell chamber assays, reverse transcription‑quantitative polymerase chain reaction, western blotting and fluorescent immunocytochemistry. Following infection with lentivirus‑mediated matriptase‑targeting small interfering RNA (siRNA), cell cycle progression and apoptosis were also analyzed. The migration distance and number of invading HO‑8910PM cells were significantly increased compared with HO‑8910 cells. HO‑8910PM cells exhibited a significantly higher ratio of matriptase/HAI‑1 mRNA levels compared with HO‑8910 cells (0.51 vs. 0.24, ~2.2 fold increase). Compared with HO‑8910 cells, the matriptase mRNA level was increased by ~3.6 fold in HO‑8910PM cells, whereas the HAI‑1 mRNA level was increased by ~1.7 fold. Similar increases in protein expression levels were also observed in HO‑8910PM cells compared with HO‑8910 cells. Migration and invasiveness were positively correlated with matriptase expression level (r=0.994, P<0.01) and the ratio of matriptase/HAI‑1 (r=0.929, P<0.01). Downregulation of matriptase using siRNA resulted in inhibition of the invasive and metastatic abilities of HO‑8910PM cells, cell cycle arrest in the G0/G1 phase and increased apoptosis. The present study demonstrated that ovarian cancer cell metastasis and invasion were more dependent on upregulation of matriptase levels than downregulation of HAI‑1. Matriptase may be a potential adjuvant therapeutic target for inhibiting ovarian cancer invasion and metastasis.

Pathophysiological roles of proteases in gastrointestinal disease

Gastrointestinal diseases, such as irritable bowel syndrome, inflammatory bowel disease, and colorectal cancer, affect a large proportion of the population and are associated with many unpleasant symptoms. Although the causes of these diseases remain largely unknown, there is increasing evidence to suggest that dysregulated protease activity may be a contributing factor. Proteases are enzymes that cleave other proteins, and their activity is normally very tightly regulated. During disease, however, the balance between proteases and their inhibitors is often shifted, leading to altered spatial and temporal control of substrate cleavage. Evaluating protease levels in normal physiology and disease has relied heavily on the use of chemical tools. Although these tools have greatly advanced the field, they are not without caveats. This review provides an introduction to these tools, their application in the gut, and a summary of the current knowledge on the contribution of protease activity to gastrointestinal disease.

Nonproliferative and Proliferative Lesions of the Gastrointestinal Tract, Pancreas and Salivary Glands of the Rat and Mouse

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) project is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature and diagnostic criteria for nonproliferative and proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and diagnostic criteria for classifying lesions in the digestive system including the salivary glands and the exocrine pancreas of laboratory rats and mice. Most lesions are illustrated by color photomicrographs. The standardized nomenclature, the diagnostic criteria, and the photomicrographs are also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and age related lesions as well as lesions induced by exposure to test items. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature and diagnostic criteria for the digestive system will decrease misunderstandings among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Extracellular: Plasma Membrane Proteases – Serine Proteases

Membrane-anchored serine proteases are a group of extracellular serine proteases tethered directly to plasma membranes, via a C-terminal glycosylphosphatidylinositol linkage (GPI-anchored), a C-terminal transmembrane domain (Type I), or an N-terminal transmembrane domain (Type II). A variety of biochemical, cellular, and in vivo studies have established that these proteases are important pericellular contributors to processes vital for the maintenance of homeostasis, including food digestion, blood pressure regulation, hearing, epithelial permeability, sperm maturation, and iron homeostasis. These enzymes are hijacked by viruses to facilitate infection and propagation, and their misregulation is associated with a wide range of diseases, including cancer malignancy.

Inhibition of Matriptase Activity Results in Decreased Intestinal Epithelial Monolayer Integrity In Vitro

Barrier dysfunction in inflammatory bowel diseases implies enhanced paracellular flux and lowered transepithelial electrical resistance (TER) causing effective invasion of enteropathogens or altered intestinal absorption of toxins and drug compounds. To elucidate the role of matriptase-driven cell surface proteolysis in the maintenance of intestinal barrier function, the 3-amidinophenylalanine-derived matriptase inhibitor, MI-432 was used on porcine IPEC-J2 cell monolayer. Studies with two fluorescent probes revealed that short (2 h) treatment with MI-432 caused an altered distribution of oxidative species between intracellular and extracellular spaces in IPEC-J2 cells. This perturbation was partially compensated when administration of inhibitor continued for up to 48 h. Significant decrease in TER between apical and basolateral compartments of MI-432-treated IPEC-J2 cell monolayers proved that matriptase is one of the key effectors in the maintenance of barrier integrity. Changes in staining pattern of matriptase and in localization of the junctional protein occludin were observed suggesting that inhibition of matriptase by MI-432 can also exert an effect on paracellular gate opening via modulation of tight junctional protein assembly. This study confirms that non-tumorigenic IPEC-J2 cells can be used as an appropriate small intestinal model for the in vitro characterization of matriptase-related effects on intestinal epithelium. These findings demonstrate indirectly that matriptase plays a pivotal role in the development of barrier integrity; thus matriptase dysfunction can facilitate the occurence of leaky gut syndrome observed in intestinal inflammatory diseases.

Microbiome, inflammation, and cancer

Inflammation has long been suspected to play a major role in the pathogenesis of cancer. Only recently, however, have some mechanisms of its tumor promoting effects become known. Microbes, both commensal and pathogenic, are critical regulators of the host immune system and, ultimately, of inflammation. Consequently, microbes have the potential power to influence tumor progression as well, through a wide variety of routes, including chronic activation of inflammation, alteration of tumor microenvironment, induction of genotoxic responses, and metabolism. In this review, we will provide a general overview of commensal microbiota, inflammation, and cancer, as well as how microbes fit into this emerging field.

The gastrointestinal microbiota and colorectal cancer

The human gut is home to a complex and diverse microbiota that contributes to the overall homeostasis of the host. Increasingly, the intestinal microbiota is recognized as an important player in human illness such as colorectal cancer (CRC), inflammatory bowel diseases, and obesity. CRC in itself is one of the major causes of cancer mortality in the Western world. The mechanisms by which bacteria contribute to CRC are complex and not fully understood, but increasing evidence suggests a link between the intestinal microbiota and CRC as well as diet and inflammation, which are believed to play a role in carcinogenesis. It is thought that the gut microbiota interact with dietary factors to promote chronic inflammation and CRC through direct influence on host cell physiology, cellular homeostasis, energy regulation, and/or metabolism of xenobiotics. This review provides an overview on the role of commensal gut microbiota in the development of human CRC and explores its association with diet and inflammation.

Mechanisms of hepatocyte growth factor activation in cancer tissues

Hepatocyte growth factor/scatter factor (HGF/SF) plays critical roles in cancer progression through its specific receptor, MET. HGF/SF is usually synthesized and secreted as an inactive proform (pro-HGF/SF) by stromal cells, such as fibroblasts. Several serine proteases are reported to convert pro-HGF/SF to mature HGF/SF and among these, HGF activator (HGFA) and matriptase are the most potent activators. Increased activities of both proteases have been observed in various cancers. HGFA is synthesized mainly by the liver and secreted as an inactive pro-form. In cancer tissues, pro-HGFA is likely activated by thrombin and/or human kallikrein 1-related peptidase (KLK)-4 and KLK-5. Matriptase is a type II transmembrane serine protease that is expressed by most epithelial cells and is also synthesized as an inactive zymogen. Matriptase activation is likely to be mediated by autoactivation or by other trypsin-like proteases. Recent studies revealed that matriptase autoactivation is promoted by an acidic environment. Given the mildly acidic extracellular environment of solid tumors, matriptase activation may, thus, be accelerated in the tumor microenvironment. HGFA and matriptase activities are regulated by HGFA inhibitor (HAI)-1 (HAI-1) and/or HAI-2 in the pericellular microenvironment. HAIs may have an important role in cancer cell biology by regulating HGF/SF-activating proteases.

The protease inhibitor HAI-2, but not HAI-1, regulates matriptase activation and shedding through prostasin

The membrane-anchored serine proteases, matriptase and prostasin, and the membrane-anchored serine protease inhibitors, hepatocyte growth factor activator inhibitor (HAI)-1 and HAI-2, are critical effectors of epithelial development and postnatal epithelial homeostasis. Matriptase and prostasin form a reciprocal zymogen activation complex that results in the formation of active matriptase and prostasin that are targets for inhibition by HAI-1 and HAI-2. Conflicting data, however, have accumulated as to the existence of auxiliary functions for both HAI-1 and HAI-2 in regulating the intracellular trafficking and activation of matriptase. In this study, we, therefore, used genetically engineered mice to determine the effect of ablation of endogenous HAI-1 and endogenous HAI-2 on endogenous matriptase expression, subcellular localization, and activation in polarized intestinal epithelial cells. Whereas ablation of HAI-1 did not affect matriptase in epithelial cells of the small or large intestine, ablation of HAI-2 resulted in the loss of matriptase from both tissues. Gene silencing studies in intestinal Caco-2 cell monolayers revealed that this loss of cell-associated matriptase was mechanistically linked to accelerated activation and shedding of the protease caused by loss of prostasin regulation by HAI-2. Taken together, these data indicate that HAI-1 regulates the activity of activated matriptase, whereas HAI-2 has an essential role in regulating prostasin-dependent matriptase zymogen activation.

Polyserase-1/TMPRSS9 induces pro-tumor effects in pancreatic cancer cells by activation of pro-uPA

Polyserase-1/TMPRSS9 is a type II transmembrane serine protease showing a complex molecular architecture characterized by the presence of three tandem serine protease domains in its amino acid sequence. This protease is widely expressed in mouse and human tissues, however, its functional significance is unknown in both normal and pathological conditions. In the present study, we evaluated the possible role of polyserase-1 in cancer progression. First, we showed that polyserase-1 increased the invasive capacities of PANC-1 and SK-PC-3 pancreatic cancer cells. Moreover, the presence of polyserase-1 enhanced anchorage-independent growth and diminished the adhesion capability of PANC-1 cells to different extracellular matrix components. These effects were mediated by the efficient conversion of pro-uPA to active uPA and high phosphorylation levels of ERK detected in the PANC-1 cells expressing exogenous polyserase-1. Collectively, our data suggest that polyserase-1 may be involved in cancer progression and, similarly to what has been proposed for the closely related serine proteases matriptase and TMPRSS4, inhibition of TMPRSS9 activity may contribute to the inhibition of tumor growth.

Potent and specific inhibition of the biological activity of the type-II transmembrane serine protease matriptase by the cyclic microprotein MCoTI-II

Matriptase is a type-II transmembrane serine protease involved in epithelial homeostasis in both health and disease, and is implicated in the development and progression of a variety of cancers. Matriptase mediates its biological effects both via as yet undefined substrates and pathways, and also by proteolytic cleavage of a variety of well-defined protein substrates, several of which it shares with the closely-related protease hepsin. Development of targeted therapeutic strategies will require discrimination between these proteases. Here we have investigated cyclic microproteins of the squash Momordica cochinchinensis trypsin-inhibitor family (generated by total chemical synthesis) and found MCoTI-II to be a high-affinity (Ki 9 nM) and highly selective (> 1,000-fold) inhibitor of matriptase. MCoTI-II efficiently inhibited the proteolytic activation of pro-hepatocyte growth factor (HGF) by matriptase but not by hepsin, in both purified and cell-based systems, and inhibited HGF-dependent cell scattering. MCoTI-II also selectively inhibited the invasion of matriptase-expressing prostate cancer cells. Using a model of epithelial cell tight junction assembly, we also found that MCoTI-II could effectively inhibit the re-establishment of tight junctions and epithelial barrier function in MDCK-I cells after disruption, consistent with the role of matriptase in regulating epithelial integrity. Surprisingly, MCoTI-II was unable to inhibit matriptase-dependent proteolytic activation of prostasin, a GPI-anchored serine protease also implicated in epithelial homeostasis. These observations suggest that the unusually high selectivity afforded by MCoTI-II and its biological effectiveness might represent a useful starting point for the development of therapeutic inhibitors, and further highlight the role of matriptase in epithelial maintenance.

Expression of matriptase correlates with tumour progression and clinical prognosis in oral squamous cell carcinoma

AIMS

To investigate the relationship of matriptase expression in oral squamous cell carcinoma (OSCC) to clinicopathological characteristics, patient survival and cell-invasive properties.

METHODS AND RESULTS

Matriptase expression in OSCC was evaluated by immunohistochemical staining, and its relationship to clinicopathological features and outcomes was assessed statistically. The shRNA-mediated stable knockdown of matriptase in OSCC cells was used to analyse cell proliferation, migration and invasion in vitro. Matriptase immunostaining score was correlated with histopathological grade, clinical stage, positive lymph node and distant metastasis, and higher matriptase immunostaining score was associated significantly with poor prognosis. Elevated matriptase expression in oral cancer cell lines was a significant promoter of oral cancer cell migration and invasion.

CONCLUSIONS

Matriptase expression correlates with tumour progression and invasive capability in OSCC and may be an adverse prognostic marker for this cancer.

Matriptase deletion initiates a Sjögren's syndrome-like disease in mice

Objective

The objective of this study was to determine the effect of epithelial barrier disruption, caused by deficiency of the membrane-anchored serine protease, matriptase, on salivary gland function and the induction of autoimmunity in an animal model.

Methods

Embryonic and acute ablation of matriptase expression in the salivary glands of mice was induced, leading to decreased epithelial barrier function. Mice were characterized for secretory epithelial function and the induction of autoimmunity including salivary and lacrimal gland dysfunction, lymphocytic infiltration, serum anti-Ro/SSA, anti-La/SSB and antinuclear antibodies. Salivary glands immune activation/regulation, barrier function as well as tight junction proteins expression also were determined. Expression of matriptase in minor salivary gland biopsies was compared among pSS patients and healthy volunteers.

Results

Embryonic ablation of matriptase expression in mice resulted in the loss of secretory epithelial cell function and the induction of autoimmunity similar to that observed in primary Sjögren’s syndrome. Phenotypic changes included exocrine gland dysfunction, lymphocytic infiltrates, production of Sjögren’s syndrome-specific autoantibodies, and overall activation of the immune system. Acute ablation of matriptase expression resulted in significant salivary gland dysfunction in the absence of overt immune activation. Analysis of the salivary glands indicates a loss of electrical potential across the epithelial layer as well as altered distribution of a tight junction protein. Moreover, a significant decrease in matriptase gene expression was detected in the minor salivary glands of pSS patients compared with healthy volunteers.

Conclusions

Our findings demonstrate that local impairment of epithelial barrier function can lead to loss of exocrine gland dysfunction in the absence of inflammation while systemic deletion can induce a primary Sjögren’s syndrome like phenotype with autoimmunity and loss of gland function.

Rodent intestinal epithelial carcinogenesis: pathology and preclinical models

Colon cancer is a major human malignancy that afflicts millions of people throughout the world each year. Genetics and diet play large roles in colon carcinogenesis although chemicals may also contribute. For the past 40 years, scientists have studied experimentally induced intestinal carcinogenesis in rodents in order to elucidate the etiology and mechanisms involved. Comparative histopathology has revealed many similarities of rodent and human intestinal cancers. Comparative molecular pathology has also shown genetic similarities. More recently, genetically engineered mice and inflammatory colon cancer models have been used for investigating mechanisms and potential chemopreventive and treatment modalities. This review will focus on comparative histopathology and nonclinical models.

Role of Janus kinase 3 in mucosal differentiation and predisposition to colitis

Janus kinase 3 (Jak3) is a nonreceptor tyrosine kinase expressed in both hematopoietic and nonhematopoietic cells. Previously, we characterized the functions of Jak3 in cytoskeletal remodeling, epithelial wound healing, and mucosal homeostasis. However, the role of Jak3 in mucosal differentiation and inflammatory bowel disease was not known. In this report, we characterize the role of Jak3 in mucosal differentiation, basal colonic inflammation, and predisposition toward colitis. Using the Jak3 knock-out (KO) mouse model, we show that Jak3 is expressed in colonic mucosa of mice, and the loss of mucosal expression of Jak3 resulted in reduced expression of differentiation markers for the cells of both enterocytic and secretory lineages. Jak3 KO mice showed reduced expression of colonic villin, carbonic anhydrase, secretory mucin muc2, and increased basal colonic inflammation reflected by increased levels of pro-inflammatory cytokines IL-6 and IL-17A in colon along with increased colonic myeloperoxidase activity. The inflammations in KO mice were associated with shortening of colon length, reduced cecum length, decreased crypt heights, and increased severity toward dextran sulfate sodium-induced colitis. In differentiated human colonic epithelial cells, Jak3 redistributed to basolateral surfaces and interacted with adherens junction (AJ) protein β-catenin. Jak3 expression in these cells was essential for AJ localization of β-catenin and maintenance of epithelial barrier functions. Collectively, these results demonstrate the essential role of Jak3 in the colon where it facilitated mucosal differentiation by promoting the expression of differentiation markers and enhanced colonic barrier functions through AJ localization of β-catenin.

A recombinant matriptase causes an increase in caspase-3 activity in a small-intestinal epithelial IEC-6 line cultured on fibronectin-coated plates

Matriptase is an epithelial-derived type-II transmembrane serine protease. This protease is expressed prominently in the villus tip of small-intestinal epithelia at which senescent cells undergo shedding and/or apoptosis. The basement membrane of epithelial cells, including small-intestinal epithelial cells, contains extracellular matrix (ECM) proteins such as fibronectin and laminin. We found previously that high concentrations of a recombinant matriptase catalytic domain (r-MatCD) (e.g. 1 μM) caused an increased detachment of and increases in the activity of apoptotic effector caspase-3 in a rat small-intestinal epithelial IEC-6 line cultured on laminin-coated plates and proposed that at sites with its high level of expression, matriptase contributes to promoting shedding and/or detachment-induced death of epithelial cells through a mechanism mediating loss of cell-ECM adhesion. In this study, we found that even without increasing cell detachment, a high concentration of r-MatCD causes an increase in caspase-3 activity in IEC-6 cells cultured on fibronectin-coated plates, suggesting that the recombinant matriptase can cause apoptosis by a mechanism unrelated to cell detachment. Also, r-MatCD-treated IEC-6 cells on fibronectin were found to display spindle-like morphological changes. We suggest that r-MatCD causes apoptosis of IEC-6 on fibronectin by a mechanism involving the disruption of cell integrity.

Hepatocyte growth factor activator inhibitor type 1 is a suppressor of intestinal tumorigenesis

Hepatocyte growth factor activator inhibitor type 1 (HAI-1/SPINT1) is a membrane-bound serine protease inhibitor expressed on the surface of epithelial cells. Although HAI-1/SPINT1 is abundantly expressed in the intestinal epithelium, its role in intestinal tumorigenesis is not known. In this study, we investigated the role of Hai-1/Spint1 in intestinal tumorigenesis using mouse models. The membranous Hai-1/Spint1 immunoreactivity was decreased in murine Apc(Min/+) tumors and also in carcinogen (azoxymethane treatment followed by dextran sodium sulfate administration)-induced colon tumors compared with the adjacent non-neoplastic epithelium. The decreased immunoreactivity appeared to be due to sheddase activity of membrane-type 1 matrix metalloprotease. Then, we examined the effect of intestine-specific deletion of Spint1 gene on Apc(Min/+) mice. The loss of Hai-1/Spint1 significantly accelerated tumor formation in Apc(Min/+) mice and shortened their survival periods. Activation of HGF was enhanced in Hai-1/Spint1-deficient Apc(Min/+) intestine. Gene expression profiling revealed upregulation of the Wnt/β-catenin signaling circuit, claudin-2 expression, and angiogenesis not only in tumor tissue but also in the background mucosa without macroscopic tumors in Hai-1/Spint1-deficient Apc(Min/+) intestine. Intestinal deletion of Spint1 also enhanced the susceptibility to carcinogen-induced colon tumorigenicity of wild-type Apc mice. Our findings suggest that HAI-1/SPINT1 has a crucial role in suppressing intestinal tumorigenesis, which implies a novel link between epithelial cell surface serine protease inhibitors and protection from carcinogenic stimuli.

Prostasin is required for matriptase activation in intestinal epithelial cells to regulate closure of the paracellular pathway

The type II transmembrane serine protease matriptase is a key regulator of epithelial barriers in skin and intestine. In skin, matriptase acts upstream of the glycosylphosphatidylinositol-anchored serine protease, prostasin, to activate the prostasin zymogen and initiate a proteolytic cascade that is required for stratum corneum barrier functionality. Here, we have investigated the relationship between prostasin and matriptase in intestinal epithelial barrier function. We find that similar to skin, matriptase and prostasin are components of a common intestinal epithelial barrier-forming pathway. Depletion of prostasin by siRNA silencing in Caco-2 intestinal epithelium inhibits barrier development similar to loss of matriptase, and the addition of recombinant prostasin to the basal side of polarized Caco-2 epithelium stimulates barrier forming changes similar to the addition of recombinant matriptase. However, in contrast to the proteolytic cascade in skin, prostasin functions upstream of matriptase to activate the endogenous matriptase zymogen. Prostasin is unable to proteolytically activate the matriptase zymogen directly but induces matriptase activation indirectly. Prostasin requires expression of endogenous matriptase to stimulate barrier formation since matriptase depletion by siRNA silencing abrogates prostasin barrier-forming activity. Active recombinant matriptase, however, does not require the expression of endogenous prostasin for barrier-forming activity. Together, these data show that matriptase and not prostasin is the primary effector protease of tight junction assembly in simple columnar epithelia and further highlight a spatial and tissue-specific aspect of cell surface proteolytic cascades.