E-cadherin variants associated with oral facial clefts trigger aberrant cell motility in a REG1A-dependent manner

BACKGROUND

Germline mutations of E-cadherin contribute to hereditary diffuse gastric cancer (HDGC) and congenital malformations, such as oral facial clefts (OFC). However, the molecular mechanisms through which E-cadherin loss-of-function triggers distinct clinical outcomes remain unknown. We postulate that E-cadherin-mediated disorders result from abnormal interactions with the extracellular matrix and consequent aberrant intracellular signalling, affecting the coordination of cell migration.

METHODS

Herein, we developed in vivo and in vitro models of E-cadherin mutants associated with either OFC or HDGC. Using a Drosophila approach, we addressed the impact of the different variants in cell morphology and migration ability. By combining gap closure migration assays and time-lapse microscopy, we further investigated the migration pattern of cells expressing OFC or HDGC variants. The adhesion profile of the variants was evaluated using high-throughput ECM arrays, whereas RNA sequencing technology was explored for identification of genes involved in aberrant cell motility.

RESULTS

We have demonstrated that cells expressing OFC variants exhibit an excessive motility performance and irregular leading edges, which prevent the coordinated movement of the epithelial monolayer. Importantly, we found that OFC variants promote cell adhesion to a wider variety of extracellular matrices than HDGC variants, suggesting higher plasticity in response to different microenvironments. We unveiled a distinct transcriptomic profile in the OFC setting and pinpointed REG1A as a putative regulator of this outcome. Consistent with this, specific RNAi-mediated inhibition of REG1A shifted the migration pattern of OFC expressing cells, leading to slower wound closure with coordinated leading edges.

CONCLUSIONS

We provide evidence that E-cadherin variants associated with OFC activate aberrant signalling pathways that support dynamic rearrangements of cells towards improved adaptability to the microenvironment. This proficiency results in abnormal tissue shaping and movement, possibly underlying the development of orofacial malformations.

Linking gene expression to clinical outcomes in pediatric Crohn's disease using machine learning

Pediatric Crohn's disease (CD) is characterized by a severe disease course with frequent complications. We sought to apply machine learning-based models to predict risk of developing future complications in pediatric CD using ileal and colonic gene expression. Gene expression data was generated from 101 formalin-fixed, paraffin-embedded (FFPE) ileal and colonic biopsies obtained from treatment-naïve CD patients and controls. Clinical outcomes including development of strictures or fistulas and progression to surgery were analyzed using differential expression and modeled using machine learning. Differential expression analysis revealed downregulation of pathways related to inflammation and extra-cellular matrix production in patients with strictures. Machine learning-based models were able to incorporate colonic gene expression and clinical characteristics to predict outcomes with high accuracy. Models showed an area under the receiver operating characteristic curve (AUROC) of 0.84 for strictures, 0.83 for remission, and 0.75 for surgery. Genes with potential prognostic importance for strictures (REG1A, MMP3, and DUOX2) were not identified in single gene differential analysis but were found to have strong contributions to predictive models. Our findings in FFPE tissue support the importance of colonic gene expression and the potential for machine learning-based models in predicting outcomes for pediatric CD.

Cell-Free DNA Methylation: The New Frontiers of Pancreatic Cancer Biomarkers' Discovery

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal cancer types world-wide. Its high mortality is related to the difficulty in the diagnosis, which often occurs when the disease is already advanced. As of today, no early diagnostic tests are available, while only a limited number of prognostic tests have reached clinical practice. The main reason is the lack of reliable biomarkers that are able to capture the early development or the progression of the disease. Hence, the discovery of biomarkers for early diagnosis or prognosis of PDAC remains, de facto, an unmet need. An increasing number of studies has shown that cell-free DNA (cfDNA) methylation analysis represents a promising non-invasive approach for the discovery of biomarkers with diagnostic or prognostic potential. In particular, cfDNA methylation could be utilized for the identification of disease-specific signatures in pre-neoplastic lesions or chronic pancreatitis (CP), representing a sensitive and non-invasive method of early diagnosis of PDAC. In this review, we will discuss the advantages and pitfalls of cfDNA methylation studies. Further, we will present the current advances in the discovery of pancreatic cancer biomarkers with early diagnostic or prognostic potential, focusing on pancreas-specific (e.g., CUX2 or REG1A) or abnormal (e.g., ADAMTS1 or BNC1) cfDNA methylation signatures in high risk pre-neoplastic conditions and PDAC.

Regenerating islet-derived 1α (REG-1α) protein increases tau phosphorylation in cell and animal models of tauopathies

REG-1α, a secreted protein containing a C-type lectin domain, is expressed in various organs and plays different roles in digestive system cells in physiological and pathological conditions. Like other members of the Reg family, REG-1α is expressed also in the brain where it has different functions. For instance, we previously reported that REG-1α regulates neurite outgrowth and is overexpressed during the very early stages of Alzheimer's disease (AD). However, REG-1α function in neural cells during neural degeneration remains unknown. First, REG-1α and phosphorylated tau expression were assessed in tissue sections from the hippocampus, representing neurofibrillary tangles (NFTs), from patients with AD, and from basal ganglia, representing subcortical NFTs, from patients with progressive supranuclear palsy (PSP). We found an association between REG-1α expression, tau hyperphosphorylation and NFTs in human brain samples from patients with these neurodegenerative diseases. Then, the effects of REG-1α overexpression on tau phosphorylation and axonal morphology were investigated i) in primary cultures of rat neurons that express human tau P301L and ii) in a transgenic zebrafish model of tauopathy that expresses human tau P301L. In the tau P301L cell model, REG-1α overexpression increased tau phosphorylation at the S202/T205 and S396 residues (early and late stages of abnormal phosphorylation, respectively) through the AKT/GSK3-β pathway. This effect was associated with axonal defects both in tau P301L-expressing rat neurons and zebrafish embryos. Our findings suggest a functional role for REG-1α during tauopathy development and progression and, specifically, its involvement in the modification of tau phosphorylation temporal sequence.

Reg proteins promote acinar-to-ductal metaplasia and act as novel diagnostic and prognostic markers in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignant tumor. Acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia (PanIN) are both precursor lesions that lead to the development of PDAC. Reg family proteins (Reg1A, 1B, 3A/G, 4) are a group of calcium-dependent lectins that promote islet growth in response to inflammation and/or injuries. The aim of this study was to establish a role for Reg proteins in the development of PDAC and their clinical value as biomarkers. We found that Reg1A and Reg3A/G were highly expressed in the ADM tissues by immunohistochemistry. In the 3-dimensional culture of mouse acinar cells, Reg3A promoted ADM formation with concurrent activation of mitogen-acitvated protein kinase. Upregulation of Reg1A and Reg1B levels was observed as benign ductal epithelium progresses from PanIN to invasive PDAC. Patients with PDAC showed significantly higher serum levels of Reg1A and Reg1B than matching healthy subjects. These results were further validated by the quantification of Reg 1A and 1B mRNA levels in the microdissected tissues (22- and 6-fold increases vs. non-tumor tissues). Interestingly, patients with higher levels of Reg1A and 1B exhibited improved survival rate than those with lower levels. Furthermore, tissue expressions of Reg1A, Reg1B, and Reg4 could differentiate metastatic PDAC in the liver from intrahepatic cholangiocarcinoma with 92% sensitivity and 95% specificity. Overall, our results demonstrate the upregulation of Reg proteins during PDAC development. If validated in larger scale, Reg1A and Reg1B could become clinical markers for detecting early stages of PDAC, monitoring therapeutic response, and/or predicting patient's prognosis.

Bacterially-Associated Transcriptional Remodelling in a Distinct Genomic Subtype of Colorectal Cancer Provides a Plausible Molecular Basis for Disease Development

The relevance of specific microbial colonisation to colorectal cancer (CRC) disease pathogenesis is increasingly recognised, but our understanding of possible underlying molecular mechanisms that may link colonisation to disease in vivo remains limited. Here, we investigate the relationships between the most commonly studied CRC-associated bacteria (Enterotoxigenic Bacteroides fragilis, pks+ Escherichia coli, Fusobacterium spp., afaC+ E. coli, Enterococcus faecalis & Enteropathogenic E. coli) and altered transcriptomic and methylation profiles of CRC patients, in order to gain insight into the potential contribution of these bacteria in the aetiopathogenesis of CRC. We show that colonisation by E. faecalis and high levels of Fusobacterium is associated with a specific transcriptomic subtype of CRC that is characterised by CpG island methylation, microsatellite instability and a significant increase in inflammatory and DNA damage pathways. Analysis of the significant, bacterially-associated changes in host gene expression, both at the level of individual genes as well as pathways, revealed a transcriptional remodeling that provides a plausible mechanistic link between specific bacterial colonisation and colorectal cancer disease development and progression in this subtype; these included upregulation of REG3A, REG1A and REG1P in the case of high-level colonization by Fusobacterium, and CXCL10 and BMI1 in the case of colonisation by E. faecalis. The enrichment of both E. faecalis and Fusobacterium in this CRC subtype suggests that polymicrobial colonisation of the colonic epithelium may well be an important aspect of colonic tumourigenesis.

Proposed mechanisms for oligonucleotide IMT504 induced diabetes reversion in a mouse model of immunodependent diabetes

Type 1 diabetes (T1D) originates from autoimmune β-cell destruction. IMT504 is an immunomodulatory oligonucleotide that increases mesenchymal stem cell cloning capacity and reverts toxic diabetes in rats. Here, we evaluated long-term (20 doses) and short-term (2-6 doses) effects of IMT504 (20 mg·kg(-1)·day(-1) sc) in an immunodependent diabetes model: multiple low-dose streptozotocin-injected BALB/c mice (40 mg·kg(-1)·day(-1) ip for 5 consecutive days). We determined blood glucose, glucose tolerance, serum insulin, islet morphology, islet infiltration, serum cytokines, progenitor cell markers, immunomodulatory proteins, proliferation, apoptosis, and islet gene expression. IMT504 reduced glycemia, induced β-cell recovery, and impaired islet infiltration. IMT504 induced early blood glucose decrease and infiltration inhibition, increased β-cell proliferation and decreased apoptosis, increased islet indoleamine 2,3-dioxygenase (IDO) expression, and increased serum tumor necrosis factor and interleukin-6 (IL-6). IMT504 affected islet gene expression; preproinsulin-2, proglucagon, somatostatin, nestin, regenerating gene-1, and C-X-C motif ligand-1 cytokine (Cxcl1) increased in islets from diabetic mice and were decreased by IMT504. IMT504 downregulated platelet endothelial cell adhesion molecule-1 (Pecam1) in islets from control and diabetic mice, whereas it increased regenerating gene-2 (Reg2) in islets of diabetic mice. The IMT504-induced increase in IL-6 and islet IDO expression and decreased islet Pecam1 and Cxcl1 mRNA expression could participate in keeping leukocyte infiltration at bay, whereas upregulation of Reg2 may mediate β-cell regeneration. We conclude that IMT504 effectively reversed immunodependent diabetes in mice. Corroboration of these effects in a model of autoimmune diabetes more similar to human T1D could provide promising results for the treatment of this disease.

The Gut Epithelial Receptor LRRC19 Promotes the Recruitment of Immune Cells and Gut Inflammation

Commensal microbes are necessary for a healthy gut immune system. However, the mechanism involving these microbes that establish and maintain gut immune responses is largely unknown. Here, we have found that the gut immune receptor leucine-rich repeat (LRR) C19 is involved in host-microbiota interactions. LRRC19 deficiency not only impairs the gut immune system but also reduces inflammatory responses in gut tissues. We demonstrate that the LRRC19-associated chemokines CCL6, CCL9, CXCL9, and CXCL10 play a critical role in immune cell recruitment and intestinal inflammation. The expression of these chemokines is associated with regenerating islet-derived (REG) protein-mediated microbiotas. We also found that the expression of REGs may be regulated by gut Lactobacillus through LRRC19-mediated activation of NF-κB. Therefore, our study establishes a regulatory axis of LRRC19, REGs, altered microbiotas, and chemokines for the recruitment of immune cells and the regulation of intestinal inflammation.

•

The gut immune receptor LRRC19 is involved in host-microbiota interactions

•

LRRC19-associated chemokines control immune cell recruitment and gut inflammation

•

Chemokines are regulated by REG protein-mediated gut microbiotas

•

Lactobacillus may modulate the expression of REG proteins through LRRC19

EXPRESSION OF REG1Α, GAST AND TGFB1 GENES IN CONDITIONS OF STRESSINDUCED GASTRIC MUCOUS LESIONS DEVELOPMENT AND HEALING IN RATS

Analysis of Reg1a gene expression in rat gastric mucosa under development and healing of stress-induced lesions was carried out. Increased expression of Reg1a was observed after 1 hour of stressor impact - 2,1 times, and achieved the maximum level expression after 3 hours of stress exposure - 3,5 times, that occurred on the background of lipid peroxidation intensification and antioxidant system dysfunction. The sharp decrease in 1,6 and 2 times of Reg1a gene expression was shown in 12 and 24 hours respectively after termination of the stressor action. Analysis of Gast gene expression did not confirm that gastrin stimulated Reg1a expression in gastric mucosa under water immersion restraint stress. The positive correlation between Reg1a and Tgfb1 genes expression was determined in the dynamics of stress-induced gastric lesions’ development and healing, which may indicate the involvement of Tgfb1 to acceleration of lesion’s healing.

Regenerating islet-derived protein 1 inhibits the activation of islet stellate cells isolated from diabetic mice

Emerging evidence indicates that the islet fibrosis is attributable to activation of islet stellate cells (ISCs). In the present study, we compared the differences in biological activity of ISCs isolated from diabetic db/db and non-diabetic db/m mice, and the effects of the regenerating islet-derived protein 1 (Reg1) on ISC function. We showed that ISCs isolated from db/db mice were activated more rapidly than those from db/m mice during culture. Both Reg1 and its putative receptor exostosin-like glycosyltransferase 3 (EXTL3) were highly expressed by diabetic ISCs. Treatment with Reg1 inhibited migration, viability, and synthesis and secretion of Type I Collagen(Col-I), Type III Collagen(Col-III) and Fibronectin(FN) by diabetic ISCs, and this was associated with deactivation of the PI3K/Akt, MAPK/Erk1/2 signaling pathway in an EXTL3-dependent manner. In conclusion, our observations (i) confirmed the presence of fibrogenic stellate cells within pancreatic islets, which are prone to be activated in Type 2 diabetes, and (ii) revealed a potential role for Reg1 in preventing ISC activation.

Synergistic activations of REG I α and REG I β promoters by IL-6 and Glucocorticoids through JAK/STAT pathway in human pancreatic β cells

Reg (Regenerating gene) gene was originally isolated from rat regenerating islets and its encoding protein was revealed as an autocrine/paracrine growth factor for β cells. Rat Reg gene is activated in inflammatory conditions for β cell regeneration. In human, although five functional REG family genes (REG Iα, REG Iβ, REG III, HIP/PAP, and REG IV) were isolated, their expressions in β cells under inflammatory conditions remained unclear. In this study, we found that combined addition of IL-6 and dexamethasone (Dx) induced REG Iα and REG Iβ expression in human 1.1B4 β cells. Promoter assay revealed that a signal transducer and activator of transcription- (STAT-) binding site in each promoter of REG Iα (TGCCGGGAA) and REG Iβ (TGCCAGGAA) was essential for the IL-6+Dx-induced promoter activation. A Janus kinase 2 (JAK2) inhibitor significantly inhibited the IL-6+Dx-induced REG Iα and REG Iβ transcription. Electrophoretic mobility shift assay and chromatin immunoprecipitation revealed that IL-6+Dx stimulation increased STAT3 binding to the REG Iα promoter. Furthermore, small interfering RNA-mediated targeting of STAT3 blocked the IL-6+Dx-induced expression of REG Iα and REG Iβ. These results indicate that the expression of REG Iα and REG Iβ should be upregulated in human β cells under inflammatory conditions through the JAK/STAT pathway.

Regenerating 1 and 3b gene expression in the pancreas of type 2 diabetic Goto-Kakizaki (GK) rats

Regenerating (REG) proteins are associated with islet development, β-cell damage, diabetes and pancreatitis. Particularly, REG-1 and REG-3-beta are involved in cell growth/survival and/or inflammation and the Reg1 promoter contains interleukin-6 (IL-6)-responsive elements. We showed by transcriptome analysis that islets of Goto-Kakizaki (GK) rats, a model of spontaneous type 2 diabetes, overexpress Reg1, 3α, 3β and 3γ, vs Wistar islets. Goto-Kakizaki rat islets also exhibit increased cytokine/chemokine expression/release, particularly IL-6. Here we analyzed Reg1 and Reg3β expression and REG-1 immuno-localization in the GK rat pancreas in relationship with inflammation. Isolated pancreatic islets and acinar tissue from male adult Wistar and diabetic GK rats were used for quantitative RT-PCR analysis. REG-1 immunohistochemistry was performed on paraffin sections with a monoclonal anti-rat REG-1 antibody. Islet cytokine/chemokine release was measured after 48 h-culture. Islet macrophage-positive area was quantified on cryostat sections using anti-CD68 and major histocompatibility complex (MHC) class II antibodies. Pancreatic exocrine-to-endocrine Reg1 and Reg3β mRNA ratios were markedly increased in Wistar vs GK rats. Conversely, both genes were upregulated in isolated GK rat islets. These findings were unexpected, because Reg genes are expressed in the pancreatic acinar tissue. However, we observed REG-1 protein labeling in acinar peri-ductal tissue close to islets and around large, often disorganized, GK rat islets, which may retain acinar cells due to their irregular shape. These large islets also showed peri-islet macrophage infiltration and increased release of various cytokines/chemokines, particularly IL-6. Thus, IL-6 might potentially trigger acinar REG-1 expression and secretion in the vicinity of large diabetic GK rat islets. This increased acinar REG-1 expression might reflect an adaptive though unsuccessful response to deleterious microenvironment.

Transcriptional activation of Reg2 and Reg3β genes by glucocorticoids and interleukin-6 in pancreatic acinar and islet cells

Reg family proteins are expressed in the pancreas and involved in pancreatitis and islet β-cell growth. In order to explore transcriptional control, we transfected luciferase reporter genes driven by Reg promoters into acinar AR42J and islet MIN6 cells. Dexamethasone (DEX) significantly increased the promoter expression of Reg2 and Reg3β genes and the levels of endogenous Reg3β mRNA and protein in AR42J cells. DEX-induced promoter activation was inhibited by the inhibitor of poly(ADP-ribose) polymerase, nicotinamide. In MIN6 cells, DEX moderately stimulated the transcription of Reg3β but not Reg2 promoter. While IL-6 alone had no effect, coculture with DEX produced a remarkable synergism on Reg3β gene transcription, which was abolished by nicotinamide. Our results demonstrated a significant and direct stimulation of Reg2 and Reg3β genes by glucocorticoids, all three were activated in response to inflammation such as in pancreatitis. Prominent stimulation of specific Reg genes by glucocorticoids may constitute a functional synergism.

Regenerating gene (REG) 1 alpha promotes pannus progression in patients with rheumatoid arthritis

INTRODUCTION

A protein analysis using mass spectrometry revealed the existence of serum proteins with significant quantitative changes after the administration of infliximab. Among these proteins, regenerating gene (REG) 1α appears to be related to the pathogenesis of rheumatoid arthritis (RA). Therefore, the present study was conducted to examine the mechanism of REG1α in RA disease progression.

METHODS

Serum samples were collected from RA patients and normal healthy controls. REG1α expression was evaluated by ELISA, RT-PCR, and indirect immunofluorescence microscopy. The functions of REG1α on synovial fibroblasts with regard to apoptosis, receptor activator of NF-κB ligand (RANKL) expression, and cellar proliferation were evaluated using siRNA to inhibit the intrinsic REG1α mRNA expression.

RESULTS

The serum concentrations of REG1α in RA patients were higher than in normal healthy controls. The high expression of REG1α was also observed in the synovial tissue of RA patients compared to those of osteoarthropathy patients. In addition, tumor necrosis factor-α (TNF-α) upregulated REG1α expression in the synovial fibroblasts cell line (MH7A). Inhibition of REG1α expression suppressed the induction of RANKL expression by TNF-α. Furthermore, exogenous recombinant REG1α protein inhibited apoptosis and promoted cell proliferation in MH7A cells. These effects were abolished in the REG1α-siRNA MH7A cells.

CONCLUSION

The present data suggest that TNF-α induces aberrant REG1α expression and that REG1α plays an important role in aberrant cell proliferation and RANKL expression of synovial fibroblasts, ultimately resulting in pannus formation. Restoration of normal physiological REG1α expression may contribute to disease amelioration.

[Small interfering RNA inhibits cell proliferation in gastric cancer cell lines highly expressing RegIα]

OBJECTIVE

To investigate the effect of small interfering RNA on cell proliferation and apoptosis in gastric cancer cell lines with high expression of RegIα.

METHODS

Total RNA was isolated from six gastric cancer cell lines,and the expression of RegI α mRNA was detected by RT-PCR. RegI α RNAi expression vector was constructed and stably transfected into MKN45 and AGS cells with high RegI α expression, empty-vector was used as control. RegI α mRNA and protein expression was measured by RT-PCR and Western blot respectively in stable transfected cell lines. Cell proliferation and apoptosis were detected with MTT assay and flow cytometry.

RESULT

RT-PCR results indicated that RegI α mRNA expression was significantly inhibited by RNAi in both cell lines compared with empty-vector. Western blot results showed that RegIα protein was down-regulated to (44 ± 4)% and (25 ± 4)% respectively in MKN45 and AGS cells compared to empty-vector. MTT results showed that cell growth was significantly inhibited in MKN45 and AGS cells. The apoptosis rate in MKN45 and AGS cells was remarkable increased compared to that of empty-vector (12.96 ± 0.50)% compared with (3.99 ± 0.30)% and (11.59 ± 1.10)% compared with (4.22 ± 0.40)% (P < 0.05).

CONCLUSION

Small interfering RNA of RegI α gene can efficiently down-regulate RegI α expression in MKN45 and AGS cell lines, and further inhibit cell growth and induce cell apoptosis.

Involvement of the IL-22/REG Ialpha axis in ulcerative colitis

The Regenerating gene (REG) Ialpha protein, a trophic and/or anti-apoptotic factor, is important in the pathophysiology of gastrointestinal inflammation. Interleukin (IL)-22 is a recently identified cytokine that is suggested to have pivotal roles in inflammatory bowel diseases. We therefore investigated the involvement of the IL-22/REG Ialpha axis and examined the mechanism of regulation of REG Ialpha expression by IL-22 stimulation in ulcerative colitis (UC) mucosa. Expression of IL-22, IL-22 receptor 1 (IL-22R1), and REG Ialpha in UC mucosa was analyzed by real-time RT-PCR and immunohistochemistry. The effects of IL-22 on REG Ialpha protein expression were examined using a small-interfering RNA for STAT3, an MAPK inhibitor or a PI3K inhibitor. The element responsible for IL-22-induced REG Ialpha promoter activation was determined by a promoter deletion and electrophoretic mobility shift assay. The expression of IL-22 was enhanced in infiltrating inflammatory cells, and that of IL-22R1 and REG Ialpha was concurrently enhanced in the inflamed epithelium in UC mucosa. The levels of REG Ialpha and IL-22 mRNA expression were strongly correlated, and the distributions of REG Ialpha- and IL-22R1-positive epithelial cells were very similar. IL-22 simulation enhanced the expression of REG Ialpha protein through STAT3 tyrosine phosphorylation in colon cancer cells. The IL-22-responsive element was located between -142 and -134 in the REG Ialpha promoter region. REG Ialpha protein may have a pathophysiological role as a biological mediator for immune cell-derived IL-22 in the UC mucosa.

Regenerating gene I regulates interleukin-6 production in squamous esophageal cancer cells

Regenerating gene (REG) I plays important roles in cancer cell biology. The purpose of this study was to determine whether REG I affects cytokine production in cancer cells. We transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Ialpha and Ibeta and examined its effects on cytokine expression. We found that transfecting TE-5 and TE-9 cells with REG I Ialpha and Ibeta led to significantly increased expression of interleukin (IL)-6 mRNA and protein, but it had little or no effect on expression of IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17A, interferon-gamma, tumor necrosis factor-alpha, granulocyte-colony stimulating factor or transforming growth factor-beta1. The elevated IL-6 expression seen in REG Ialpha transfectants was silenced by small interfering RNA-mediated knockdown. These finding suggest that REG I may act through IL-6 to exert effects on squamous esophageal cancer cell biology.

[The relation between reg 1A mRNA expression and the clinicopathologic parameters in the patients with primary gastric carcinoma]

Using reverse transcriptase-polymerase chain reaction (RT-PCR), REG 1A mRNA expression was investigated in 235 primary gastric carcinoma samples. And the relation between these results with the clinicopathologic parameters of primary gastric carcinoma was discussed in experiment. The positive REG 1A mRNA is 78% (183/235) of primary gastric carcinoma which revealed by RT-PCR analysis. Moreover, patients with REG 1A-positive differentiated adenocarcinoma were found to have a significantly poorer prognosis compared with REG 1A-negative tumor patients. REG IA mRNA is closely linked to the infiltrative growth pattern and with signet ring cell carcinoma and poorly differentitated adencarcinoma. And the incidence of venous invasion of REG 1A-positive tumors was significantly higher than that of REG 1A-negative tumors. So the results of the experiment demonstrate that the expression of the REG 1A gene is closely related to the infiltrating property of primary gastric carcinoma, and may be as a prognostic indicator of differentiated adenocarcinoma of the stomach in clinic diagnosis.

[Effect of Astragalus polysaccharide on pancreatic cell mass in type 1 diabetic mice]

OBJECTIVE

To study the effect of Astragalus polysaccharide (APS) on pancreatic beta cell mass in type 1 diabetic mice.

METHOD

Diabetic mice induced by multiple low dose streptozotocin (MLD-STZ) were administered either APS (100, 200, 400 mg x kg(-1) body weight) or saline intraperitoneally daily, and sacrificed after 15 or 30 days of treatment. Streptavidin-peroxidase immunohistochemical method with counterstain was performed to determine the effect of APS on insulitis. Indirect double immunofluorescence for Insulin/Ki67 (counterstained by Hoechst33258) and Insulin/Cleaved caspase-3 was used to evaluate pancreatic cell (besides beta cell) proliferation, beta cell neogenesis, beta cell apoptosis and beta cell mass. Semi-quantitative RT-PCR was utilized to characterize pancreatic regenerating protein 1 mRNA levels, and ELISA method was performed to measure the levels of cytokine IFN-gamma and IL-4 secreted by splenocytes.

RESULT

Attenuated insulitis, upregulated beta cell mass, increased number of neogenetic pancreas islets, decreased number of apoptosis beta cells and downregulation of Th1/Th2 cytokine ratio were significantly time-and dose-dependent on APS treatment, when compared to saline controls. However, no significant differences of the number of pancreatic proliferative cells or replicative cells and pancreatic regenerating protein 1 mRNA levels were demonstrated between APS (APS100, APS200 and APS400) and saline vehicle group on day 15 and 30 with APS treatment.

CONCLUSION

APS can upregulate pancreatic beta cell mass in type 1 diabetic mice, strongly associated with improved autoimmunity.

Helicobacter and gastrin stimulate Reg1 expression in gastric epithelial cells through distinct promoter elements

The gastric pathogen Helicobacter pylori accelerates the progression to gastric cancer but the precise mechanisms that mediate carcinogenesis remain unidentified. We now describe how Helicobacter and gastrin stimulate the expression of a putative growth factor, Reg1, in primary gastric epithelial cells. RT-PCR and Western immunoblotting of human gastric corpus and antrum showed significantly increased Reg1alpha in H. pylori-infected patients. Similarly, Reg1 was increased in the stomachs of H. felis-infected INS-GAS mice. To study transcriptional regulation of the Reg1 gene, we transfected primary mouse gastric glands with -2111 bp and -104 bp Reg1 promoter-luciferase reporter constructs. Expression of both constructs was detected in pepsinogen- and VMAT-2-expressing cells, which corresponds to the normal pattern of expression of human and mouse endogenous Reg1. The expression of both constructs was increased in response to gastrin and H. pylori, and there were potentiating interactions between them; in contrast, only the -2111 bp construct responded to H. felis. Mutation of a C-rich putative regulatory element within the -104 bp sequence abolished the response to gastrin but not to H. pylori whereas mutation of the proximal -98 to -93 region of the promoter reduced the response to H. pylori but not to gastrin. Stimulation of Reg1 by H. pylori required the virulence factor CagA. These data indicate that expression of the putative growth factor Reg1 is controlled through separate promoter elements by gastrin and Helicobacter.

Expression of the genes dual oxidase 2, lipocalin 2 and regenerating islet-derived 1 alpha in Crohn's disease

OBJECTIVE

A global gene expression profile of non-inflamed colonic mucosal cells from patients with Crohn's disease (CD) and of colonic mucosal cells from controls was performed.

MATERIAL AND METHODS

Tissue specimens from macroscopically non-inflamed descending colon were obtained colonoscopically from 33 CD patients and from 17 control subjects. All controls and 10 CD patients were medication-free at the time of colonoscopy. The Human Genome U133 Plus 2.0 GeneChip Array was used for gene profiling. Hybridization data were analysed with dChip software. Results were confirmed by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Protein product expression of selected genes was assessed by immunohistochemistry using the Envision+ visualization technique.

RESULTS

The expression profile was not homogeneous with the statistical cut-point settings applied. In comparison with controls, it was found that 19 CD patients had three differentially expressed genes, two of them related to the innate immune system: dual oxidase 2 on chromosome 15 (DUOX2, fold change 4.1) and lipocalin 2 on chromosome 9 (LCN2, fold change 3.1). The third gene, regenerating islet-derived 1 alpha (REG1A, fold change 3.9), codes for a mitogenic protein; this could not be confirmed by RT-PCR. Medication-free patients had no differentially expressed genes as compared with controls. Immunohistochemistry indicated that these proteins were produced by epithelial cells (REG1A, LCN2) and leucocytes (DUOX2 and LCN2).

CONCLUSIONS

As compared with controls, non-inflamed colonic mucosal cells contain two up-regulated genes related to the innate immune system. Up-regulation of these genes, known to be induced by microorganisms, suggests either increased microflora antigenicity or an altered function in mucosal barrier defence.

Dysregulation of Reg gene expression occurs early in gastrointestinal tumorigenesis and regulates anti-apoptotic genes

Expression of anti-apoptotic genes is frequently elevated in tumors, where they increase resistance to chemotherapeutic agents and predict poor patient outcomes. However, key cellular factors regulating anti-apoptotic genes in tumors remain unknown. Increased expression of the regenerating (Reg) genes is commonly observed in gastrointestinal (GI) malignancies including colorectal cancer (CRC). We therefore examined Reg gene expression and associated changes in anti-apoptotic genes in an animal model of GI tumorigenesis. Using real time RT-PCR, we measured expression of Reg genes in human colorectal adenocarcinoma specimens, colon adenocarcinoma cell lines and adenomas from multiple intestinal neoplasia (min) mice heterozygous for a germ-line mutation of the adenomatous polyposis coli (APC) gene. Expression of Reg genes is increased in human colorectal adenocarcinomas and in the intestine of APCmin/+ mice at four weeks of age, a time preceding the spontaneous second mutation in the APC gene. Individual Reg genes exhibited regional expression profiles across the GI tract in mice. Adenomas from 14-week old mice had significant increases in at least one member of the Reg gene family, most commonly Reg IV and an associated increase in expression of the anti-apoptotic gene, Bcl-2. Addition of exogenous recombinant human Reg IV to human colon adenocarcinoma cells significantly increased Bcl-2 and Bcl-xL expression and induced resistance to ionizing radiation. These results show that dysregulation of Reg genes occur early in tumorigenesis. Furthermore, increased expression of Reg genes, specifically Reg IV contribute to adenoma formation and lead to increased resistance to apoptotic cell death in CRC.

Reg (regenerating) gene overexpression in islets from non-obese diabetic mice with accelerated diabetes: role of IFNbeta

AIMS/HYPOTHESIS

The expression of IFNbeta in beta cells results in accelerated type 1 diabetes. The REG family of beta cell proliferation factors have been described as autoantigens in autoimmune diabetes. The aim of this study was to determine the effect of IFNbeta on Reg expression, and the implications of this in terms of autoimmunity.

METHODS

Reg gene expression was determined in islets from non-obese diabetic (NOD) RIP-HuIFNbeta mice by cDNA microarray, quantitative real-time PCR and immunohistochemistry. The effect of IFNbeta on Reg1 and Reg2 expression was assessed in the NOD insulinoma cell line NIT-1. IL-6, known to induce Reg expression, was measured in the insulitis microenvironment. Morphological studies were carried out to determine islet enlargement in this model.

RESULTS

Reg2 was upregulated in islets from the NOD RIP-HuIFNbeta mice at the onset of the autoimmune attack. IFNbeta upregulates Reg1 and Reg2 genes in NIT-1 cells. The expression of Il6 was increased in islets from transgenic mice and in NIT-1 cells exposed to HuIFNbeta. Moreover, islets from transgenic mice were enlarged compared with those from wild-type mice.

CONCLUSIONS/INTERPRETATION

Reg overexpression correlates well with the acceleration of diabetes in this model. The upregulation of Reg suggests that islets try to improve hyperglycaemia by regenerating the cells lost in the autoimmune attack. Reg expression is regulated by several factors such as inflammation. Therefore, the overexpression of an IFNbeta-induced autoantigen (REG) in the islets during inflammation might contribute to the premature onset of diabetes.

Reg I-knockout mice reveal its role in regulation of cell growth that is required in generation and maintenance of the villous structure of small intestine

Reg I (regenerating gene product I) is a growth factor that plays a central role in the generation and regeneration of the gastric mucosal architecture. On the other hand, mouse Reg I mRNA is expressed at the highest levels in the small intestine among the gastrointestinal tissues. In the current study, with the aim to clarify the role of Reg I protein in the small intestine, the temporal and spatial pattern of Reg I expression and the phenotype of Reg I-knockout mice in the tissue were examined. In the wild-type mice, immunohistochemistry localized Reg I protein expression in absorptive cells located in the lower half of the intestinal villi. Reg I expression was undetectable until embryonic day 13 (E13), when the fetal intestine still lacks villous structure; however, it dramatically increased at E17 along with the formation and maturation of the fetal intestinal villi. In the small intestine of the adult Reg I-knockout mice, less densely packed, round-shaped aberrant morphology of the absorptive cells was observed light microscopically, and electron microscopical examination revealed a strikingly loose connection of these cells to the basement membrane. Antiproliferating cell nuclear antigen staining and anti-Ki67 staining demonstrated the marked decrease in the number of proliferating cells in the small intestinal mucosa of the knockout mice. The cell migration speed visualized by one shot labeling of 5-bromodeoxyuridine was significantly slower in the knockout mice. These phenotypes of Reg I-knockout mice emerged, in accordance with the temporal pattern of Reg I expression described above, from E17. Reg I was considered to be a regulator of cell growth that is required to generate and maintain the villous structure of the small intestine.

Pancreatic regenerating protein (reg I) and reg I receptor mRNA are upregulated in rat pancreas after induction of acute pancreatitis

AIM: Pancreatic regenerating protein (regI) stimulates pancreatic regeneration after pancreatectomy and is mitogenic to ductal and β-cells. This suggests that regIand its receptor may play a role in recovery after pancreatic injury. We hypothesized that regIand its receptor are induced in acute pancreatitis.

METHODS: Acute pancreatitis was induced in male Wistar rats by retrograde injection of 3% sodium taurocholate into the pancreatic duct. Pancreata and serum were collected 12, 24, and 36 hours after injection and from normal controls (4 rats/group). RegIreceptor mRNA, serum regIprotein, and tissue regIprotein levels were determined by Northern analysis, enzyme-linked immunosorbent assay (ELISA), and Western analysis, respectively. Immunohistochemistry was used to localize changes in regIand its receptor.

RESULTS: Serum amylase levels and histology confirmed necrotizing pancreatitis in taurocholate treated rats. There was no statistically significant change in serum regIconcentrations from controls. However, Western blot demonstrated increased tissue levels of regIat 24 and 36 h. This increase was localized primarily to the acinar cells and the ductal cells by immunohistochemistry. Northern blot demonstrated a significant increase in regIreceptor mRNA expression with pancreatitis. Immunohistochemistry localized this increase to the ductal cells, islets, and acinar cells.

CONCLUSION: Acute pancreatitis results in increased tissue regIprotein levels localized to the acinar and ductal cells, and a parallel threefold induction of regIreceptor in the ductal cells, islets, and acinar cells. These changes suggest that induction of regIand its receptor may be important for recovery from acute pancreatitis.

Activation of the Reg family genes by pancreatic-specific IGF-I gene deficiency and after streptozotocin-induced diabetes in mouse pancreas

We have recently reported that Pdx1-Cre-mediated whole pancreas inactivation of IGF-I gene [in pancreatic-specific IGF-I gene-deficient (PID) mice] results in increased beta-cell mass and significant protection against both type 1 and type 2 diabetes. Because the phenotype is unlikely a direct consequence of IGF-I deficiency, the present study was designed to explore possible activation of proislet factors in PID mice by using a whole genome DNA microarray. As a result, multiple members of the Reg family genes (Reg2, -3alpha, and -3beta, previously not known to promote islet cell growth) were significantly upregulated in the pancreas. This finding was subsequently confirmed by Northern blot and/or real-time PCR, which exhibited 2- to 8-fold increases in the levels of these mRNAs. Interestingly, these Reg family genes were also activated after streptozotocin-induced beta-cell damage and diabetes (wild-type T1D mice) when islet cells were undergoing regeneration. Immunohistochemistry revealed increased Reg proteins in exocrine as well as endocrine pancreas and suggested their potential role in beta-cell neogenesis in PID or T1D mice. Previously, other Reg proteins (Reg1 and islet neogenesis-associated protein) have been shown to promote islet cell replication and neogenesis. These uncharacterized Reg proteins may play a similar but more potent role, not only in normal islet cell growth in PID mice, but also in islet cell regeneration after T1D.

Cyclin D1 activation through ATF-2 in Reg-induced pancreatic beta-cell regeneration

Regenerating gene product (Reg) is induced in pancreatic beta-cells and acts as an autocrine/paracrine growth factor for regeneration via a cell surface Reg receptor. However, the manner by which Reg induces beta-cell regeneration was unknown. In the present study, we found that Reg increased phospho-ATF-2, which binds to -57 to -52 of the cyclin D1 gene to activate the promoter. The Reg/ATF-2-induced cyclin D1 promoter activation was attenuated by PI(3)K inhibitors such as LY294002 and wortmannin. In Reg knockout mouse islets, the levels of phospho-ATF-2, cyclin D1, and phospho-Rb were greatly decreased. These results indicate that the Reg-Reg receptor system stimulates the PI(3)K/ATF-2/cyclin D1 signaling pathway to induce beta-cell regeneration.

Overexpression of regenerating islet-derived 1 alpha and 3 alpha genes in human primary liver tumors with β-catenin mutations

The Wnt/beta-catenin signaling pathway is activated in many human hepatocellular carcinomas (HCC). We tried to identify the genes involved in carcinogenesis and progression of HCC with beta-catenin mutations. We used PCR-based subtractive hybridization to compare gene expression between malignant and benign components of a human HCC occurring in pre-existing adenoma activated for beta-catenin. Two of the genes identified belong to the Regenerating gene (REG) family. They encode the Regenerating islet-derived 3 alpha (REG3A/HIP/PAP/REG-III) and 1 alpha (REG1A) proteins, both involved in liver and pancreatic regeneration and proliferation. Using siRNA directed against beta-catenin, we demonstrated that REG3A is a target of beta-catenin signaling in Huh7 hepatoma cells. The upregulation of REG3A and REG1A expression is significantly correlated to the beta-catenin status in 42 HCC and 28 hepatoblastomas characterized for their beta-catenin status. Thus, we report strong evidence that both genes are downstream targets of the Wnt pathway during liver tumorigenesis.

Possible role of REG Ialpha protein in ulcerative colitis and colitic cancer

BACKGROUND AND AIMS

Although regenerating gene (REG) Ialpha protein may be involved in the inflammation and carcinogenesis in the gastrointestinal tract, its pathophysiological role in ulcerative colitis (UC) and the resulting colitic cancer remains unclear. We investigated expression of the REG Ialpha gene and its protein in UC and colitic cancer tissues. We examined whether cytokines are responsible for REG Ialpha gene expression and whether REG Ialpha protein has a trophic and/or an antiapoptotic effect on colon cancer cells.

METHODS

Expression of REG Ialpha mRNA and its gene product in UC tissues was analysed by real time reverse transcription-polymerase chain reaction and immunohistochemistry, respectively. The effects of cytokines on REG Ialpha promoter activity were examined in LoVo cells by luciferase reporter assay. The effects of REG Ialpha protein on growth and H(2)O(2) induced apoptosis were examined in LoVo cells by MTT and TUNEL assays, respectively.

RESULTS

REG Ialpha protein was strongly expressed in inflamed epithelium and in dysplasias and cancerous lesions in UC tissues. The level of REG Ialpha mRNA expression in UC tissues correlated significantly with severity of inflammation and disease duration. REG Ialpha promoter activity was enhanced by stimulation with interferon gamma or interleukin 6. REG Ialpha protein promoted cell growth and conferred resistance to H(2)O(2) induced apoptosis in LoVo cells. REG Ialpha protein promoted Akt phosphorylation and enhanced Bcl-xL and Bcl-2 expression in LoVo cells.

CONCLUSIONS

The REG Ialpha gene is inducible by cytokines and its gene product may function as a mitogenic and/or an antiapoptotic factor in the UC-colitic cancer sequence.