Expression of REG III and prognosis in head and neck cancer

Alteration in Melanin Content in Retinal Pigment Epithelial Cells upon Hydroquinone Exposure

Abnormal pigmentation or depigmentation of the retinal pigment epithelium (RPE) is a precursor to neovascular age-related macular degeneration (nAMD). In this study, we evaluated the effects of hydroquinone (HQ), the most potent reductant in cigarette smoke, on the melanin production in RPE cells. Induced pluripotent stem cell (iPS)-derived RPE and adult retinal pigment epithelial (ARPE-19) cells were cultured with HQ. Real-time reverse transcription polymerase chain reaction revealed that the expression of melanin-related genes decreased due to the addition of HQ for 1 day. Enzyme-linked immunosorbent immunoassay showed that the concentration of melanin significantly decreased due to the addition of HQ for 24 h. A suspension of RPE cells with HQ for 24 h was prepared, and the absorbance was measured. The absorbance decreased particularly under blue light, suggesting that blue light may reach the choroid and cause choroidal inflammation. Additionally, melanin levels significantly decreased due to the addition of HQ for 1 week. After blue light irradiation on the RPE with HQ for 1 week, the vascular endothelial growth factor in the medium was significantly higher in the HQ group than in the control group. HQ-induced changes in melanin production may be responsible for the uneven pigmentation of the RPE, and these changes may cause nAMD.

The regenerating protein 3A: a crucial molecular with dual roles in cancer

Introduction

REG3A, a member of the third subclass of the Reg family, has been found in a variety of tissues but is not detected in immune cells. In the past decade, it has been determined that REG3A expression is regulated by injury, infection, inflammatory stimuli, and pro-cytokines via different signaling pathways, and it acts as a tissue-repair, bactericidal, and anti-inflammatory molecule in human diseases. Recently, the role of REG3A in cancer has received increasing attention. The present article aims to investigate the structure, expression, regulation, function of REG3A, and to highlight the potential role of REG3A in tumors.

Methods

A detailed literature search and data organization were conducted to find information about the role of REG3A in variety of physiological functions and tumors.

Results

Contradictory roles of REG3A have been reported in different tumor models. Some studies have demonstrated that high expression of REG3A in cancers can be oncogenic. Other studies have shown decreased REG3A expression in cancer cells as well as suppressed tumor growth.

Conclusions

Taken together, better understanding of REG3A may lead to new insights that make it a potentially useful target for cancer therapy.

Okamoto model for necrosis and its expansions, CD38-cyclic ADP-ribose signal system for intracellular Ca2+ mobilization and Reg (Regenerating gene protein)-Reg receptor system for cell regeneration

In pancreatic islet cell culture models and animal models, we studied the molecular mechanisms involved in the development of insulin-dependent diabetes. The diabetogenic agents, alloxan and streptozotocin, caused DNA strand breaks, which in turn activated poly(ADP-ribose) polymerase/synthetase (PARP) to deplete NAD+, thereby inhibiting islet β-cell functions such as proinsulin synthesis and ultimately leading to β-cell necrosis. Radical scavengers protected against the formation of DNA strand breaks and inhibition of proinsulin synthesis. Inhibitors of PARP prevented the NAD+ depletion, inhibition of proinsulin synthesis and β-cell death. These findings led to the proposed unifying concept for β-cell damage and its prevention (the Okamoto model). The model met one proof with PARP knockout animals and was further extended by the discovery of cyclic ADP-ribose as the second messenger for Ca2+ mobilization in glucose-induced insulin secretion and by the identification of Reg (Regenerating gene) for β-cell regeneration. Physiological and pathological events found in pancreatic β-cells have been observed in other cells and tissues.

Fifteen mRNA-lncRNA expression-based signature predicted the survival of late-staged head and neck squamous cell carcinoma

Background: Gene expression is necessary for regulation in almost all biological processes, at the same time, it is related to the prognosis for head and neck squamous cell carcinoma (HNSCC). The prognosis of late-staged HNSCC is important because of its guiding significance on the therapy strategies.

Methods: In this work, we analyzed the relationship between gene expression and HNSCC in The Cancer Genome Atlas (TCGA) cohort, and optimized the panel with random forest survival analysis. Subsequently, a Cox multivariate regression-based model was developed to predict the clinical outcome of HNSCC. The performance of the model was assayed in the training cohort and validated in another three independent cohorts (GSE41614, E-TABM-302, E-MTAB-1328). The underlying pathways significantly associated with the model were identified. According to the results, patients of low-score group (median survival months: 27.4, 95% CI: 18.2–43) had a significant poor survival than those of high-score group (median survival months: 69.4, 95% CI: 58.7–72.1, P=2.7e-5), and the observation was repeatable in the other validation cohorts. Further analysis revealed that the model performed better than the other clinical indicators and is independent of these indicators.

Results: Comparison revealed that the model performed better than existing models for late HNSCC prognosis. Gene set enrichment analysis (GSEA) elucidated that the model was significantly associated with various cell processes and pathways.

Screening and identification of potential target genes in head and neck cancer using bioinformatics analysis

Head and neck cancer (HNC) is the sixth most common cancer worldwide. Recent studies on the pathogenesis of HNC have identified some biochemical associations of this disease, but the molecular mechanisms are not clear. To explore the genetic alterations in head and neck tumors, to identify new high-specificity and high-sensitivity tumor markers, and to investigate potentially effective therapeutic targets, in silico methods were used to study HNC. The GSE58911 microarray dataset was downloaded from the Gene Expression Omnibus online database to identify potential target genes in the carcinogenesis and progression of HNC. Differentially expressed genes (DEGs) were identified and functional enrichment analysis was performed. In addition, a protein-protein interaction network was also constructed, and gene analysis was undertaken using Search Tool for the Retrieval of Interacting Genes and Cytoscape. A total of 648 differentially expressed genes were identified. Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology functional enrichment analysis of DEGs included muscle system process, extracellular matrix organization, actin binding, structural molecule activity, structural constituent of muscle, extracellular region part, ECM-receptor interaction, amoebiasis, focal adhesion, drug metabolism-cytochrome P450, and chemical carcinogenesis. There were 26 hub genes identified and biological process analysis revealed that these genes were mainly enriched in extracellular matrix organization, serine-type endopeptidase activity, extracellular matrix, and complement and coagulation cascades. Survival analysis revealed that interleukin (IL)-8 (C-X-C motif chemokine ligand 8), IL1B, and serpin family A member 1 may be involved in the carcinogenesis of HNC. In summary, the DEGs and hub genes identified in the present study may increase understanding of the molecular mechanisms of development of HNC and provide potential target genes for clinical diagnosis and targeted therapy.

Effects of concentration of amyloid β (Aβ) on viability of cultured retinal pigment epithelial cells

Background

Amyloid beta (Aβ) is a constituent of drusen that is a common sign of age-related macular degeneration (AMD). The purpose of this study was to investigate the effect of Aβ on human retinal pigment epithelial (RPE) cells in culture.

Methods

Cells from a human RPE cell line (ARPE-19) were exposed to 0 to 25 μM of Aβ 1–40 for 48 h, and the number of living cells was determined by WST-8 cleavage. Replicative DNA synthesis was measured by the incorporation of 5′-bromo-2′-deoxyuridine. The cell death pathway was investigated by the WST-8 cleavage assay after the addition of caspase-9 inhibitor, an anti-apoptotic factor. Real-time qRT-PCR was performed using Aβ-exposed cellular RNA to determine the level of vascular endothelial growth factor (VEGF)-A and pigment epithelium derived factor (PEDF). To determine the effect of receptor-for-advanced glycation end products (RAGE), the siRNA for RAGE was inserted into ARPE-19 treated with Aβ, and the levels of expression of VEGF-A and PEDF were determined.

Results

The number of living ARPE-19 cells was increased by exposure to 5 μM Aβ but was decreased by exposure to 25 μM of Aβ. Replicative DNA synthesis by ARPE-19 cells exposed to 25 μM of Aβ was significantly decreased indicating that 25 μM of Aβ inhibited cell proliferation. Real-time RT-PCR showed that the level of the mRNA of PEDF was increased by exposure to 5 μM Aβ, and the levels of the mRNAs of PEDF and VEGF-A were also increased by exposure to 25 μM Aβ. The addition of an inhibitor of caspase-9 blocked the decrease the number of ARPE-19 cells exposed to 25 μM Aβ. Exposure to si-RAGE attenuated the increase of VEGF-A and PEDF mRNA expression in ARPE-19 exposed to Aβ.

Conclusions

Exposure of ARPE-19 cells to low concentrations of Aβ increases the level of PEDF which then inhibits the apoptosis of ARPE-19 cells leading to RPE cell proliferation. Exposure to high concentrations of Aβ induces RPE cell death and enhances the expression of the mRNA of VEGF-A in RPE cells. The Aβ-RAGE pathway may lead to the expression VEGF-A and PEDF in RPE cells. These results suggest that Aβ is strongly related to the pathogenesis of choroidal neovascularization.

Significance of Interleukin-6/STAT Pathway for the Gene Expression of REG Iα, a New Autoantigen in Sjögren's Syndrome Patients, in Salivary Duct Epithelial Cells

The regenerating gene, Reg, was originally isolated from a rat regenerating islet complementary DNA (cDNA) library, and its human homologue was named REG Iα. Recently, we reported that REG Iα messenger RNA (mRNA), as well as its product, was overexpressed in ductal epithelial cells in the salivary glands of Sjögren's syndrome patients. Furthermore, autoantibodies against REG Iα were found in the sera of Sjögren's syndrome patients, and the patients who were positive for the anti-REG Iα antibody showed significantly lower saliva secretion than antibody-negative patients. We found the mechanism of REG Iα induction in salivary ductal epithelial cells. Reporter plasmid containing REG Iα promoter (-1190/+26) upstream of a luciferase gene was introduced into human NS-SV-DC and rat A5 salivary ductal cells. The cells were treated with several cytokines (interleukin (IL)-6, IL-8, etc.), upregulated in Sjögren's syndrome salivary ducts, and the transcriptional activity was measured. IL-6 stimulation significantly enhanced the REG Iα promoter activity in both cells. Deletion analysis revealed that the -141∼-117 region of the REG Iα gene was responsible for the promoter activation by IL-6, which contains a consensus sequence for signal transducer and activator of transcription (STAT) binding. The introduction of small interfering RNA for human STAT3 abolished IL-6-induced REG Iα transcription. These results indicated that IL-6 stimulation induced REG Iα transcription through STAT3 activation and binding to the REG Iα promoter in salivary ductal cells. This dependence of REG Iα induction upon IL-6/STAT in salivary duct epithelial cells may play an important role in the pathogenesis/progression of Sjögren's syndrome.

Expression of REG family genes in human inflammatory bowel diseases and its regulation

The pathophysiology of inflammatory bowel disease (IBD) reflects a balance between mucosal injury and reparative mechanisms. Some regenerating gene (Reg) family members have been reported to be expressed in Crohn's disease (CD) and ulcerative colitis (UC) and to be involved as proliferative mucosal factors in IBD. However, expression of all REG family genes in IBD is still unclear. Here, we analyzed expression of all REG family genes (REG Iα, REG Iβ, REG III, HIP/PAP, and REG IV) in biopsy specimens of UC and CD by real-time RT-PCR. REG Iα, REG Iβ, and REG IV genes were overexpressed in CD samples. REG IV gene was also overexpressed in UC samples. We further analyzed the expression mechanisms of REG Iα, REG Iβ, and REG IV genes in human colon cells. The expression of REG Iα was significantly induced by IL-6 or IL-22, and REG Iβ was induced by IL-22. Deletion analyses revealed that three regions (- 220 to - 211, - 179 to - 156, and - 146 to - 130) in REG Iα and the region (- 274 to- 260) in REG Iβ promoter were responsible for the activation by IL-22/IL-6. The promoters contain consensus transcription factor binding sequences for MZF1, RTEF1/TEAD4, and STAT3 in REG Iα, and HLTF/FOXN2F in REG Iβ, respectively. The introduction of siRNAs for MZF1, RTEF1/TEAD4, STAT3, and HLTF/FOXN2F abolished the transcription of REG Iα and REG Iβ. The gene activation mechanisms of REG Iα/REG Iβ may play a role in colon mucosal regeneration in IBD.

Effect of resveratrol on cancer progression through the REG Ⅲ expression pathway in head and neck cancer cells

Identification of reliable markers of chemo- and radiosensitivity and the key molecules that enhance the susceptibility of head and neck squamous cell carcinoma (HNSCC) to anticancer treatments is highly desirable. Previously, we have reported that regenerating gene (REG) Ⅲ expression was such a marker associated with an improved survival rate for HNSCC patients. In the present study, we investigated the stimulators for induction of REG Ⅲ expression using REG Ⅲ promoter assay in HNSCC cells transfected with REG Ⅲ promoter vector. We tested inflammatory cytokines, growth factors, polyphenols, PPARγ activator of thiazolidinediones, and histone deacetylase inhibitors, and found that 3,4',5-trihydroxy-trans-stilbene (resveratrol) significantly increased the REG Ⅲ promoter activity and the mRNA levels of REG Ⅲ in HNSCC cells. Moreover, we demonstrated the effect of resveratrol on cancer cell progression, such as cell proliferation, chemo‑ and radiosensitivity and cancer invasion of HNSCC cells. Resveratrol significantly inhibited cell growth, enhanced chemo‑ and radiosensitivity, and blocked cancer invasion of HNSCC cells. These data suggested that resveratrol could inhibit cancer progression through the REG Ⅲ expression pathway in HNSCC cells.

Global gene expression profiling using heterologous DNA microarrays to analyze alterations in the transcriptome of Mus spretus mice living in a heavily polluted environment

Microarray platforms are a good approach for assessing biological responses to pollution as they enable the simultaneous analyses of changes in the expression of thousands of genes. As an omic and non-targeted methodology, this technique is open to unforeseen responses under particular environmental conditions. In this study, we successfully apply a commercial oligonucleotide microarray containing Mus musculus whole-genome probes to compare and assess the biological effects of living in a heavily polluted settlement, the Domingo Rubio stream (DRS), at the Huelva Estuary (SW Spain), on inhabitant free-living Mus spretus mice. Our microarray results show that mice living in DRS suffer dramatic changes in gene and protein expression compared with reference specimens. DRS mice showed alteration in the oxidative status of hepatocytes, with activation of both the innate and the acquired immune responses and the induction of chronic inflammation, accompanied by metabolic alterations that imply the accumulation of lipids in the liver (hepatic steatosis). The identified deregulated genes may be useful as biomarkers of environmental pollution.

Recombinant Reg3α protein protects against experimental acute pancreatitis in mice

Regenerating gene 3α (Reg3α) protein is a trophic factor that stimulates cell and tissue proliferation, neogenesis and also acts against apoptosis and necrosis. In order to explore the potential roles of recombinant Reg3α (rReg3α), we produced a mature rReg3α polypeptide for direct administration in l-arginine (L-Arg) induced acute pancreatitis (AP) in mice. Our results showed that rReg3α stimulated cell proliferation through Erk1/2 and p38 phosphorylation and also cyclin D1 upregulation mediated by Akt/ATF-2 signaling. Moreover, rReg3α administration significantly reduced the pancreatic damage caused by L-Arg injection, as shown in histological examination and serum amylase, lipase and C-reactive protein (CRP) assays. Not only acinar cell necrosis but also apoptosis found in the pancreas of AP mice were alleviated by rReg3α. Finally, upregulated Bcl-2 and Bcl-xL and suppressed poly (ADP-ribose) synthetase/polymerase (PARP) levels were detected as being relevant to the mechanism of rReg3α protection. We therefore conclude that rReg3α acts as a protective polypeptide against AP in mice by enhancing Bcl-2 and Bcl-xL expressions and suppressing PARP level.

Regenerating gene (REG) product and its potential clinical usage

INTRODUCTION

The regenerating gene (Reg) was identified in regenerating islets and its related genes were revealed to constitute the Reg gene family. Reg family proteins act as growth factors for several cells. Recently, autoimmunity against the Reg family proteins has been reported in several diseases. In addition, the Reg family genes were found to be expressed in a large number of cancers and to influence prognosis.

AREAS COVERED

The historical background and current view of the structure, function, and expression of Reg family genes/proteins and their physiological/pathological significance in several diseases are described. Based on the findings, the diagnostic/therapeutic potential of Reg family genes/proteins is also discussed.

EXPERT OPINION

Autoimmunity against Reg family proteins may be a new diagnostic marker and/or therapeutic target for immune-mediated diseases. Treatment aimed at the expansion of the β-cell mass by the Reg genes/proteins, combined with the abrogation of autoimmunity, constitutes a potential approach for the treatment of diabetes. Conversely, some cancer cells have gained the ability to overexpress the Reg genes/proteins, thereby enhancing their proliferative capacities, resulting in these cells having a considerable growth advantage. Thus, the Reg genes/proteins are expected to be a new prognostic marker in cancer and/or a future therapeutic target.

Human retinal pigment epithelial cell proliferation by the combined stimulation of hydroquinone and advanced glycation end-products via up-regulation of VEGF gene

Although recent research showed that advanced glycation endproduct (AGE) and hydroquinone (HQ) are related to the pathogenesis of age-related macular degeneration (AMD), the mechanism how AGE and HQ induce or accelerate AMD remains elusive. In the present study, we examined the effects of AGE and HQ on changes of human retinal pigment epithelial (RPE) cell numbers and found that the viable cell numbers were markedly reduced by HQ by apoptosis and that AGE prevented the decreases of HQ-treated cell numbers by increased replicative DNA synthesis of RPE cells without changing apoptosis. Real-time RT-PCR revealed that vascular endothelial growth factor (VEGF)-A mRNA was increased by HQ treatment and the addition of HQ+AGE resulted in a further increment. The increase of VEGF secretion was confirmed by ELISA, and inhibition of VEGF signaling by chemical inhibitors and small interfering RNA decreased the HQ+AGE-induced increases in RPE cell numbers. The deletion analysis demonstrated that -102 to -43 region was essential for the VEGF-A promoter activation. Site-directed mutaions of specificity protein 1 (SP1) binding sequences in the VEGF-A promoter and RNA interference of SP1 revealed that SP1 is an essential transcription factor for VEGF-A expression. These results indicate that HQ induces RPE cell apoptosis, leading to dry AMD, and suggest that AGE stimulation in addition to HQ enhances VEGF-A transcription via the AGE-receptor for AGE pathway in HQ-damaged cells. As a result, the secreted VEGF acts as an autocrine/paracrine growth factor for RPE and/or adjacent vascular cells, causing wet AMD.

REG Iα gene expression is linked with the poor prognosis of lung adenocarcinoma and squamous cell carcinoma patients via discrete mechanisms

The aim of the present study was to evaluate the effects of the REG Iα and REG Iβ genes on lung cancer cell lines, and thereafter, the expression of REG family genes (REG Iα, REG Iβ, REG III, HIP/PAP and REG IV) in lung cancer in relation to patient prognosis was evaluated. Lung adenocarcinoma (AD) and squamous cell carcinoma (SCC) cell lines expressing REG Iα or REG Iβ (HLC-1 REG Iα/Iβ and EBC-1 REG Iα/Iβ) were established, and cell number, cell invasive activity, and anchorage-independent cell growth were compared with these variables in the control cells. The expression levels of REG family genes were evaluated by real-time RT-PCR in surgically resected lung cancers, and disease-specific survival (DSS) curves were generated. The HLC-1 REG Iα/Iβ cell line showed significant increases in cell number and anchorage-independent cell growth compared with the control cells. EBC-1 REG Iα/Iβ cells showed significant increases in cell invasive activity and anchorage-independent cell growth as compared with the control cells. Except for the REG Iβ gene, expression of other REG family genes was observed in the surgically resected samples; however, DSS was significantly worse only in stage I patients who were positive for REG Iα expression than in patients who were negative for REG Iα expression. The effects of REG Iα on AD and SCC cells were different in the in vitro study, and a correlation between REG Iα expression and patient prognosis was noted in the in vivo study. Therefore, overexpression of REG Iα is a risk factor for poor prognosis caused by discrete mechanisms in AD and SCC patients.