REG gene expression is associated with the infiltrating growth of gastric carcinoma

Upregulation of REG IV gene in human intestinal epithelial cells by lipopolysaccharide via downregulation of microRNA-24

The pathophysiology of inflammatory bowel diseases (IBD) reflects a balance between mucosal injury and reparative mechanisms. Some regenerating gene (Reg) family members (REG Iα, REG Iβ and REG IV) are expressed in Crohn's disease (CD) and ulcerative colitis (UC) and involved as proliferative mucosal factors in IBD. We revealed that REG Iα and REG Iβ were induced in cell culture system by IL‐6/IL‐22. Although REG IV was upregulated in IBD biopsy samples, the upregulation of REG IV was not at all induced in cell culture by autoimmune‐related cytokines such as IL‐6, IL‐22 and TNFα. Here, we analysed REG IV expression in LS‐174 T and HT‐29 human intestinal epithelial cells by real‐time RT–PCR and elisa. REG IV expression was induced by lipopolysaccharide (LPS). However, LPS did not activate REG IV promoter activity. As the LPS‐induced upregulation of REG IV was considered to be regulated post‐transcriptionally, we searched targeted microRNA (miR), which revealed that REG IV mRNA has a potential target sequence for miR‐24. We measured the miR‐24 level of LPS‐treated cells and found that the level was significantly lower. The LPS‐induced increase of REG IV mRNA was abolished by the introduction of miR‐24 mimic but not by non‐specific control RNA.

The Potential Role of REG Family Proteins in Inflammatory and Inflammation-Associated Diseases of the Gastrointestinal Tract

Regenerating gene (REG) family proteins serve as multifunctional secretory molecules with trophic, antiapoptotic, anti-inflammatory, antimicrobial and probably immuno-regulatory effects. Since their discovery, accumulating evidence has clarified the potential roles of the REG family in the occurrence, progression and development of a wide range of inflammatory and inflammation-associated diseases of the gastrointestinal (GI) tract. However, significant gaps still exist due to the undefined nature of certain receptors, regulatory signaling pathways and possible interactions among distinct Reg members. In this narrative review, we first describe the structural features, distribution pattern and purported regulatory mechanisms of REG family proteins. Furthermore, we summarize the established and proposed roles of REG proteins in the pathogenesis of various inflammation-associated pathologies of the GI tract and the body as a whole, focusing particularly on carcinogenesis in the ulcerative colitis—colitic cancer sequence and gastric cancer. Finally, the clinical relevance of REG products in the context of diagnosis, treatment and prognostication are also discussed in detail. The current evidence suggests a need to better understanding the versatile roles of Reg family proteins in the pathogenesis of inflammatory-associated diseases, and their broadened future usage as therapeutic targets and prognostic biomarkers is anticipated.

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.

Expression of human REG family genes in inflammatory bowel disease and their molecular mechanism

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 the REG family genes in IBD is still unclear. Here, we analyzed expression of all the REG family genes (REGIα, REGIβ, 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 LS-174T and HT-29 human colonic epithelial 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~- 211, - 179~- 156, and - 146~- 130) in REG Iα and the region (- 274~- 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 siRNA 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.

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.

Decreased REG1α expression suppresses growth, invasion and angiogenesis of bladder cancer

BACKGROUND

Previous study has indicated association between REG1α and bladder cancer. The aim of this study was to investigate the role of Regenerating gene I alpha (REG1α) in bladder cancer.

METHODS

The role of REG1α in bladder cancer cell proliferation, migration and VEGF-induced angiogenesis was explored in vitro and in vivo. Immunohistochemistry (IHC) analysis was assessed to determine the expression of REG1α in ten paired bladder cancer and adjacent non-cancerous tissues, and in 296 bladder cancer samples.

RESULTS

Down-regulation of REG1α expression significantly reduced the proliferation, migration, invasion and VEGF-induced angiogenesis in vitro and the growth of xenograft tumors in vivo. VEGF expression in bladder cancer is associated with REG1α expression and recurrence. REG1α was overexpressed in bladder cancer tissues compared with adjacent normal samples. Patients with elevated REG1α exhibited shorter recurrence times and poor survival.

CONCLUSION

Downregulation of REG1α expression can reduce tumor growth, migration, invasion and angiogenesis. Our study demonstrates that REG1α can be used as a marker of recurrence and prognosis in bladder cancer. Therefore, REG1α targeting in bladder cancer patients represents a promising therapeutic strategy.

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.

Prognostic role of regenerating gene-I in patients with stage-IV head and neck squamous cell carcinoma

Background

Regenerating gene (REG) family is composed of antiapoptotic factors and growth factors that affect epithelial cells within the digestive system. Regenerating gene-I has been studied in different cancers. However, it has never been studied in head and neck cancer. We investigated the expression of REG-I in head and neck SCC and its relevance to patient survival rates.

Methods

Untreated biopsy specimens of 60 patients with stage IV head and neck SCC were collected, and the expression of REG-I was evaluated using immunohistochemistry. The association between REG-I expression and clinico-pathological features or survival status of the patients was assessed by Chi-square test, Fisher’s exact test and Kaplan-Meier method. Cox proportional hazard model was used to identify the independent prognostic factors.

Results

Incidence of lymphatic permeation, vascular invasion and pathological lymph nodes was significantly higher in REG-I negative group (p = 0.008, 0.030 and 0.015, respectively). Overall and cancer-free survival rates were significantly higher in REG-I positive group (p = 0.000434 and 1.0847E-8, respectively). Univariate analysis showed that REG-I was an independent prognostic factor for predicting long-term overall survival (p = 0.002), and multivariate analysis showed that REG-I and lymphatic permeation were independent prognostic factors for predicting long-term disease-free survival (p = 0.001 and 0.022, respectively).

Conclusion

Our results showed for the first time that, REG-I is expressed in head and neck SCC. REG-I expression is associated with a longer survival status. We conclude that, REG-I might be a prognostic marker in head and neck SSC and should be further investigated.

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.

Effect of REG Iα protein on angiogenesis in gastric cancer tissues

Regenerating gene (REG) Iα is not only overexpressed in a subset of gastric cancers, but also involved in tumor progression. However, the mechanism by which (REG) Iα promotes tumor growth is not fully understood. In the present study, we investigated whether REG Iα plays a role in angiogenesis during the progression of gastric cancers. Expression of REG Iα and its receptor (EXTL3; exostoses like-3) was examined using immunohistochemistry in specimens of human gastric cancer. Microvessel density (MVD) in gastric cancer tissues was evaluated using an image analysis system after CD34 immunostaining. Relationships among clinicopathological features, REG Iα expression and MVD in gastric cancer tissues were analyzed. Effects of REG Iα protein on HUVEC cells in terms of proliferation and anti-apoptosis were assessed by WST-1 assay and FACS, respectively. Furthermore, the intracellular signaling by which REG Iα exerts its biological roles was examined in vitro. REG Iα expression was significantly related to lymph node metastasis and its receptor EXTL3 was ubiquitously expressed in not only the tumor cells, but also the tumor vessel cells in the gastric cancer tissues. MVD was significantly higher in gastric cancers that were REG Iα-positive than in those that were negative. Treatment with REG Iα protein promoted growth and anti-apoptosis through activation of the ERK and Akt signaling pathways in HUVEC cells, whereas these effects were attenuated by treatment with anti-REG Iα -antibody. REG Iα protein may play a role in angiogenesis during progression of gastric cancer.

REG Iα activates c-Jun through MAPK pathways to enhance the radiosensitivity of squamous esophageal cancer cells

Identification of the key molecules that mediate susceptibility to anticancer treatments would be highly desirable. Based on clinical and cell biological studies, we recently proposed that regenerating gene (REG) Iα may be such a molecule. In the present study, we hypothesized that REG Iα increases radiosensitivity through activation of mitogen-activated protein kinase (MAPK) pathways. To test that idea, we transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Iα and examined its involvement in MAPK signaling and its effect on susceptibility to radiotherapy. We found that REG Iα-expressing cells showed increased expression of c-Jun messenger RNA (mRNA) and phospho-c-Jun protein mediated via the c-Jun N-terminal kinase (JNK) pathway and extracellular signal-regulated kinase (ERK) pathway, as well as increased radiosensitivity. Immunohistochemical analysis confirmed the activation of c-Jun in tumors expressing REG Iα. Collectively, these findings suggest that REG Iα activates c-Jun via the JNK and ERK pathway, thereby enhancing radiosensitivity.

Involvement of autoimmunity to REG, a regeneration factor, in patients with primary Sjögren's syndrome

The regenerating gene (Reg) was isolated originally as a gene specifically over-expressed in regenerating pancreatic islets and constitute a growth factor family. Reg gene product (Reg) is important in the pathophysiology of various human inflammatory diseases. Recently, the possible involvement of human REG in the regeneration of salivary ductal epithelial cells of patients with primary Sjögren's syndrome (SS) was reported. However, the expression of the REG family genes in minor salivary glands (MSG) and the occurrence of anti-REG Iα autoantibodies in SS patients were obscured. In this study, we examined the expression of REG family genes in the MSG of SS and screened anti-REG Iα autoantibodies in SS. The mRNA levels of REG family genes in MSG were quantified using real-time reverse transcription-polymerase chain reaction (RT-PCR) and REG Iα expression in the MSG was analysed by immunohistochemistry. The mRNA level of REG Iα in the MSG of SS patients was significantly higher than that of control. REG Iα protein was expressed highly in SS ductal epithelial cells. Anti-REG Iα autoantibodies in the sera were found in 11% of SS. All the MSG in the anti-REG Iα autoantibody-positive group showed REG Iα expression, whereas only 40% showed REG Iα expression in the anti-REG Iα autoantibody-negative group. The anti-REG Iα autoantibody-positive group showed significantly lower saliva secretion and a higher ratio of grade 4 (by Rubin-Holt) in sialography. These data suggest strongly that autoimmunity to REG Iα might play a role in the degeneration of MSG ductal epithelial cells in primary SS.

Reg proteins and their roles in inflammation and cancer of the human digestive system

The regenerating gene (Reg) family is a group of small molecules that includes four members found in various species, although only three are found in human tissues. Their expression is stimulated by certain growth factors or cytokines. The Reg family plays different roles in proliferation, migration, and anti-apoptosis through activating different signaling pathways. Their dysexpression is closely associated with a number of human conditions and diseases such as inflammation and cancer, especially in the human digestive system. Clinically, upregulation of Reg proteins is usually demonstrated in histological sections and sera from cancer patients. Therefore, Reg proteins can predict the progression and prognosis of cancers, especially those of the digestive tract, and can also act as diagnostic markers and therapeutic targets.

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.

REG Iα is a biomarker for predicting response to chemotherapy with S-1 plus cisplatin in patients with unresectable stage IV gastric cancer

Background:

The regenerating gene Iα (REG Iα) is involved in gastric carcinogenesis as an antiapoptotic factor. Therefore, we investigated whether REG Iα confers resistance to chemotherapeutic drugs in gastric cancer (GC) cells and whether REG Iα expression is useful for predicting the response to chemotherapy and outcome in patients with GC.

Methods:

A total of 70 patients with unresectable stage IV GC received first-line chemotherapy with S-1 and cisplatin (S-1/CDDP). The expression of REG Iα was evaluated immunohistochemically using biopsy samples obtained before chemotherapy, and its relationship to clinicopathological parameters was analysed statistically. The effects of REG Iα gene induction on resistance to 5-FU or CDDP treatment were examined by cell survival assay and flow cytometry.

Results:

Of the 70 patients with unresectable stage IV GC, 19 (27%) were positive for REG Iα expression. The expression of REG Iα was independently predictive of poorer progression-free and overall survival in such patients (hazard ratio (HR) 2.46; P=0.002 and HR 1.89; P=0.037, respectively). The gene induction of REG Iα conferred resistance to cell death induced by 5-FU or CDDP in GC cells.

Conclusion:

In patients with stage IV GC, REG Iα, which confers resistance to chemotherapeutic drugs in GC cells, is a potential biomarker for predicting resistance to S-1/CDDP treatment.

Inhibitory effects of eupatilin on tumor invasion of human gastric cancer MKN-1 cells

Extracts of the whole herb of Artemisia asiatica Nakai (Asteraceae) are used in traditional oriental medicine to treat inflammation. Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) is one of the pharmacologically active components found in A. asiatica, and has been shown to possess anti-tumoral effects in some malignancies, including gastric cancer. However, its anti-metastatic effect in gastric cancer is hardly known. In this study, anti-metastatic effect of eupatilin was investigated in the human gastric cancer cell line, MKN-1. Eupatilin inhibited MKN-1 growth in a dose- and a time-dependent manner, and induced apoptosis with a concomitant increase of caspase-3 activity. ELISA demonstrated that release of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, and IL-8) was significantly reduced by eupatilin. And p-AKT and p-ERK (p44/42) was reduced. Expression level of β-catenin and integrin was reduced and p-GSKβ was increased. In transcription reporter system, the activity of the transcriptional factor, NF-κB, was reduced by eupatilin and the expression of p65 was down-regulated when MKN-1 cells were treated with eupatilin. Moreover, a zymography study revealed that this reduction in invasive potential resulted from a reduction in type IV collagenolytic (gelatinolytic) activity. The expressions of metalloproteinases (MMP-2 and MMP-9) were also reduced in MKN-1 cells treated with eupatilin. In vitro invasion assay, eupatilin inhibited MKN-1 penetrating reconstituted basement membrane barriers. These results suggest that eupatilin inhibits the MKN-1 gastric cancer cell proliferation via activation of caspase-3 and the metastatic potential of gastric cancer cells via down-regulation of NF-κB activity followed by reduction of pro-inflammatory cytokine-mediated MMPs expressions.

Urinary levels of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein as a diagnostic biomarker in patients with bladder cancer

Background

To assess the possibility of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP) as a biological marker for detecting Bladder cancer (BCa), we examined the expression of HIP/PAP in both BCa specimens and BCa cell lines and measured HIP/PAP levels in urine from patients with BCa.

Methods

HIP/PAP expression in BCa samples was evaluated by western blot analysis, and urinary levels of HIP/PAP in patients with BCa were measured by enzyme-linked immunosorbent assay. Urine samples were collected from 10 healthy volunteers and 109 with benign urological disorders as controls, and from 101 patients who were diagnosed with BCa.

Results

HIP/PAP was highly expressed in BCa samples as compared with control bladder. Urinary HIP/PAP concentrations were significantly higher in BCa patients than in controls (median value; 3.184 pg/mL vs. 55.200 pg/mL, P <0.0001, by Mann–Whitney U test). Urinary HIP/PAP levels in BCa patients correlated positively with pathological T stages and progression-risk groups among non-muscle invasive BCa (P = 0.0008, by Kruskal-Wallis test). Regarding the recurrence-risk classifications of non-muscle invasive BCa, the urinary levels of HIP/PAP were significantly higher in the intermediate than in the low risk group (P = 0.0002, by Mann–Whitney U test). Based on a cut-off of 8.5 pg/mL, the ability of urinary HIP/PAP levels to detect BCa had a sensitivity of 80.2%, specificity of 78.2%, positive predictive value (PPV) of 75.7%, and negative predictive value (NPV) of 82.3%.

Conclusions

HIP/PAP was abundantly expressed in BCa, and the urinary levels of HIP/PAP could be a novel and potent biomarker for detection of BCa, and also for predicting the risks of recurrence- and progression-risk of non-muscle invasive BCa. A large scale study will be needed to establish the usefulness of this biomarker.

Upregulation of REG Ialpha accelerates tumor progression in pancreatic cancer with diabetes

Diabetes is now generally accepted as a crucial event in the process of pancreatic cancer (PaC). However, molecular mechanisms underlying the relationship between diabetes and PaC are not fully understood. Regenerating gene (REG) Ialpha is a growth factor affecting pancreatic islet beta cells, and it has been shown to be involved in the carcinogenesis in gastrointestinal tract. It is rational to speculate that REG Ialpha plays a potential role in the pathogenesis of PaC with diabetes. The aim of this study was to evaluate the REG Ialpha protein expression profile in PaC with and without diabetes, and define the contribution of REG Ialpha on PaC development. We found that REG Ialpha protein preferentially expressed in cancerous tissues of PaC patients with diabetes by Western blot. REG Ialpha positive cancer cells in PaC with diabetes (n = 38) was significantly higher than that in subjects without diabetes (n = 42, p < 0.05) by immunohistochemical analysis. Furthermore, we found that overexpression of REG Ialpha protein in PaC cell lines resulted in accelerated cell proliferation and consequently tumor growth, both in vitro and in vivo. The findings suggest that REG Ialpha may act as one of the tumor promoter and contribute to the aggressive nature of PaC, especially in the subpopulation with diabetes. This study would shed new insights for understanding the molecular mechanisms underlying the link between diabetes and PaC.

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.

Expression profile of REG family proteins REG Ialpha and REG IV in advanced gastric cancer: comparison with mucin phenotype and prognostic markers

Regenerating gene family members 1 (REG Ialpha) and 4 (REG IV) are overexpressed in a subset of gastric cancers. However, comparative characterization of the expression of these family proteins has remained unclear. Therefore, we aimed to elucidate not only the association between REG protein expression and mucin phenotype but also their significance as a prognostic marker for patients with gastric cancer. The expression of REG Ialpha, REG IV, CDX2, MUC2, and MUC5AC in gastric cancer tissues was examined by immunohistochemistry. The relationship between REG protein expression and clinicopathological parameters or mucin phenotype was then analyzed. REG Ialpha and REG IV expression was positive in 33 (52%) and 31 (49%) of 63 gastric cancers examined, respectively. REG Ialpha expression was significantly related to venous invasion and tumor stage, whereas REG IV expression showed no relationship to clinicopathological features. With regard to mucin phenotype, REG IV expression was significantly correlated with MUC2 and CDX2 expression, suggesting an association with the intestinal mucin phenotype of gastric cancer. On the other hand, REG Ialpha expression had no correlation with MUC2, CDX2, or MUC5AC in gastric cancer tissues. Expression of REG Ialpha but not REG IV was an independent predictor of poor outcome in patients with gastric cancer. In addition, patients with gastric cancer negative for both REG Ialpha and REG IV expression had a significantly better outcome than patients positive for either REG Ialpha or REG IV. Profiling of REG protein expression is useful to for prognostication of patients with gastric cancer.

Pancreatitis-associated protein is related closely to neoplastic proliferative activity in patients with colorectal carcinoma

Pancreatitis-associated protein (PAP) is a secretory protein that is not only expressed during acute pancreatitis but also in pancreatic adenocarcinoma, gastric carcinoma, hepatocellular carcinoma, and colorectal carcinoma. Expression in carcinoma might be another characteristic of PAP. The aim of our study was to assess, in 27 patients undergoing surgery for colorectal carcinoma, the expression of the PAP mRNA and to evaluate its association with DNA ploidy and proliferative activity (S-phase fraction, SPF) by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometric analysis (FCM). PAP mRNA was expressed in 29.6% (8 of 27) of the patients with colorectal carcinoma. DNA aneuploid and high SPF were found in 87.5% (7 of 8) of patients with PAP mRNA positive colorectal carcinoma. The serum PAP level was significantly elevated in patients with colorectal carcinoma when compared with the healthy subjects. Twelve of the 27 patients with colorectal carcinoma had high serum PAP concentrations (>25 ng/mL) and the mean SPF was 17.82% +/- 8.02%, which was significantly higher compared with the normal colorectal tissue group (7.33% +/- 3.18%, P < 0.05). The mean serum PAP concentration of DNA aneuploidy colorectal carcinomas was 46.67 +/- 17.58 ng/mL, which was significantly different when compared with the DNA diploidy group (19.18 +/- 8.89 ng/mL, P < 0.05). PAP mRNA expression and serum PAP levels are closely related to neoplastic proliferative activity in patients with colorectal carcinoma. No significant differences are observed between PAP mRNA expression and clinicopathologic parameters (P > 0.05).

REG1A predicts recurrence in stage Ta/T1 bladder cancer

AIMS

Stage Ta/T1 urothelial carcinoma of the bladder (Ta/T1 BC) has a marked tendency to recur. Regenerating protein 1 A (REG1A) has been reported to be expressed in human cancers, and it may be positively correlated with patient's prognosis. The aim of the present study was to evaluate the prognostic value of REG1A in Ta/T1 BC.

METHODS

Immunohistochemistry was done on 110 paraffin-embedded specimens of human Ta/T1 BC to detect the proteins REG1A, PCNA and MMP2. The relationships between REG1A expression and the clinical-pathological characteristics of Ta/T1 BC patients were evaluated.

RESULTS

Sixty-five out of 110 specimens were REG1A-positive. Grade and expression levels of MMP2 and REG1A were significantly correlated with the recurrence rate. REG1A expression (Hazard ratio: 3.1; 95% CI: 1.1-8.5; P=0.030) was an independent predictor of recurrence rate in multivariate Cox regression analysis. A significant association between REG1A expression and MMP2 expression (P=0.023) was also observed.

CONCLUSION

Expression of REG1A is an independent predictor of recurrence in Ta/T1 BC.

Thiazolidinediones inhibit REG Ialpha gene transcription in gastrointestinal cancer cells

REG (Regenerating gene) Ialpha protein functions as a growth factor for gastrointestinal cancer cells, and its mRNA expression is strongly associated with a poor prognosis in gastrointestinal cancer patients. We here demonstrated that PPARgamma-agonist thiazolidinediones (TZDs) inhibited cell proliferation and REG Ialpha protein/mRNA expression in gastrointestinal cancer cells. TZDs inhibited the REG Ialpha gene promoter activity, via its cis-acting element which lacked PPAR response element and could not bind to PPARgamma, in PPARgamma-expressing gastrointestinal cancer cells. The inhibition was reversed by co-treatment with a specific PPARgamma-antagonist GW9662. Although TZDs did not inhibit the REG Ialpha gene promoter activity in PPARgamma-non-expressing cells, PPARgamma overexpression in the cells recovered their inhibitory effect. Taken together, TZDs inhibit REG Ialpha gene transcription through a PPARgamma-dependent pathway. The TZD-induced REG Ialpha mRNA reduction was abolished by cycloheximide, indicating the necessity of novel protein(s) synthesis. TZDs may therefore be a candidate for novel anti-cancer drugs for patients with gastrointestinal cancer expressing both REG Ialpha and PPARgamma.

REG I enhances chemo- and radiosensitivity in squamous cell esophageal cancer cells

Identification of reliable markers of chemo- and radiosensitivity and the key molecules that enhance the susceptibility of squamous esophageal cancer cells to anticancer treatments would be highly desirable. To test whether regenerating gene (REG) I expression enhances chemo- and radiosensitivity in esophageal squamous cell carcinoma cells, we used MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays to compare the chemo- and radiosensitivities of untransfected TE-5 and TE-9 cells with those of cells stably transfected with REG Ialpha and Ibeta. We then used flow cytometry to determine whether REG I expression alters cell cycle progression. No REG I mRNA or protein were detected in untransfected TE-5 and TE-9 cells. Transfection with REG Ialpha and Ibeta led to strong expression of both REG I mRNA and protein in TE-5 and TE-9 cells, which in turn led to significant increases in both chemo- and radiosensitivity. Cell cycle progression was unaffected by REG I expression. REG I thus appears to enhance the chemo- and radiosensitivity of squamous esophageal cancer cells, which suggests that it may be a useful target for improved and more individualized treatments for patients with esophageal squamous cell carcinoma.

REG1A expression is an independent factor predictive of poor prognosis in patients with breast cancer

BACKGROUND

Regenerating gene I alpha (REG1A) is a growth factor known to affect pancreatic islet beta cells. Although REG1A expression has also been observed in various malignant tumors, the correlation between REG1A expression and the clinicopathological characteristics of breast cancer and patient prognosis has not been evaluated.

METHODS

Resected breast cancer tissues obtained at surgery from 150 breast cancer patients was stained with anti-REG1A antibody, after which the relative area occupied by stained tumor cells was evaluated under a light microscope and correlated with known clinicopathological factors.

RESULTS

Whereas tumor cells were frequently stained with anti-REG1A antibody, cells from normal breast tissue were not stained. REG1A expression in tumors of breast cancer patients with HER2-positive disease was higher than those with HER2-negative disease (P = .0009). The 10-year disease-specific survival rate among patients with lower levels of REG1A was significantly better than among those with higher levels (P = .0002 by log rank test). Multivariate Cox proportional hazard analyses revealed REG1A (hazard ratio, 2.07; 95% confidence interval, 1.93 to 11.29; P = .0005) and axillary lymph node status (hazard ratio, 4.44; 95% confidence interval, 1.52 to 11.29; P = .0003) to be independent factors affecting the 10-year disease-specific survival rate.

CONCLUSION

High levels of REG1A expression within tumors are an independent predictor of poor prognosis in patients with breast cancer.

REG Ialpha is a reliable marker of chemoradiosensitivity in squamous cell esophageal cancer patients

BACKGROUND

A reliable marker of chemoradiosensitivity that would enable appropriate and individualized treatment of thoracic squamous cell esophageal cancer has long been sought. We investigated whether regenerating gene (REG) Ialpha is such a marker.

METHODS

We assessed expression of REG Ialpha in untreated endoscopic biopsy specimens and examined the correlation between REG Ialpha expression and the clinical responses to definitive chemoradiotherapy and prognosis. We also examined the relationship between REG Ialpha expression in the resected tumor and the prognosis of patients who received esophagectomy for thoracic squamous cell esophageal cancer.

RESULTS

Among the 42 patients treated with definitive chemoradiotherapy, 8 of the 23 REG I-positive patients (35%) showed complete responses to chemoradiotherapy, while only one of the 19 REG I-negative patients did so. The survival rate among the REG I-positive patients was significantly better than among the REG I-negative patients. For the 76 patients treated surgically, there was no significant difference in the survival rates among the REG I-positive and REG I-negative patients.

CONCLUSIONS

REG Ialpha expression in squamous cell esophageal carcinoma may be a reliable marker of chemoradiosensitivity. We anticipate that it will enable us to provide more appropriate and individualized treatment to patients of advanced esophageal squamous cell carcinoma.

REG1A expression is an independent factor predictive of poor prognosis in patients with non-small cell lung cancer

Regenerating gene I alpha (REG1A) is a known growth factor affecting pancreatic islet beta cells. Although REG1A expression also has been observed in various tumors, the correlation between REG1A expression and the clinicopathological characteristics of non-small cell lung cancer (NSCLC) and patient prognosis has not been evaluated.

METHODS

We used real-time semi-quantitative reverse transcription polymerase chain reaction to assess REG1A mRNA expression in tumor samples from 86 NSCLC patients. We then correlated REG1A mRNA expression with known clinicopathological factors. We also used immunohistochemical staining to determine the source of REG1A.

RESULTS

Within samples of tumor tissue, the cytosol of tumor cells was stained with anti-REG1A antibody. Cells from normal tissue were not stained. The 5-year over-all survival rate among patients expressing lower levels of REG1A was significantly better than among those expressing higher levels of REG1A (P=0.0031 by log-rank test). Multivariate Cox proportional hazard analyses revealed REG1A (hazard ratio, 2.34; 95% CI, 1.25-5.90; P=0.0055) and pathological stage III (hazard ratio, 3.46; 95% CI, 1.52-14.82; P=0.0012) to be independent factors affecting the 5-year over-all survival rate.

CONCLUSION

High levels of REG1A expression by tumor cells are an independent predictor of a poor prognosis in patients with NSCLC.

Searching urinary tumor markers for bladder cancer using a two-dimensional differential gel electrophoresis (2D-DIGE) approach

Aiming at identifying biomarkers for bladder cancer, the urinary proteome was explored through a two-dimensional gel-based proteomic approach (2D-DIGE) coupled with mass spectrometry and database interrogation. The increased expression of proteins differentially expressed between patients with bladder tumors and controls such as Reg-1 and keratin 10 was confirmed to be associated with bladder cancer progression on bladder cancer cell lines by immunoblotting, and bladder tumors by immunohistochemistry. Moreover, the association of these proteins, especially Reg-1, with tumor staging and clinical outcome was confirmed by immunohistochemistry using an independent series of bladder tumors contained in tissue microarrays (n=292). Furthermore, Reg-1 was quantified using an independent series of urinary specimens (n=80) and provided diagnostic utility to discriminate patients with bladder cancer and controls (area under the curve (AUC=0.88)). Thus, the 2D-DIGE approach has identified Reg-1 as a biomarker for bladder cancer diagnostics, staging, and outcome prognosis.

Molecular markers for gastric adenocarcinoma: an update

Gastric cancer is the second most common cancer worldwide. Treatment of localized gastric cancer relies primarily on surgical intervention, although growing evidence suggests that the addition of chemoradiation may improve disease-free intervals and overall survival. In this regard, the current high rates of recurrence and subsequent poor survival have prompted an ever-increasing use of multimodal strategies, even for early-stage disease. However, these therapies are often limited by debilitating toxicities and varying degrees of response efficacy. As a result, pharmacogenomics, the study of specific genetic and molecular signatures that may be predictive of treatment outcomes, has gained considerable interest. For example, studies have demonstrated that the expression of enzymes involved in the metabolism or conjugation of commonly used chemotherapy agents, such as fluoropyrimidines and cisplatin, can serve as surrogate markers predictive of chemotherapy response. Polymorphisms in the genes encoding these enzymes have also been identified and may further account for altered expression patterns, resulting in varied clinical responses. Future work is necessary to further refine the list of molecular genetic markers and to identify novel markers for prognostic and predictive purposes. Technologies such as microarray analysis may be useful in identifying new molecular genetic markers, and further work may determine whether these markers can be employed to help stratify patients into different multimodal treatment regimens.

STAT3 activation regulates growth, inflammation, and vascularization in a mouse model of gastric tumorigenesis

BACKGROUND & AIMS

The gp130(757F/F) mouse is a well-characterized and robust model of distal gastric tumorigenesis displaying many of the characteristics of human intestinal type gastric cancer. Key to the development of tumors in this model, and in many examples of human tumor development, is hyperactivation of the transcription factor STAT3. This study addressed the requirement for STAT3 activation in tumor initiation and characterized some of the genes downstream of STAT3 required for tumor development. Furthermore, the interaction among STAT3, the microbial environment, and tumorigenesis was evaluated.

METHODS

The role of STAT3 in gastric tumor development was assessed in detail in gp130(757F/Y757F):STAT3(+/-) mice displaying reduced STAT3 activity. Tumor size was quantified morphologically, and the effects on endocrine cell populations, neovascularization, and inflammatory cell infiltration as well as the outcome of STAT3 activation on transcription of a number of genes relevant in growth and inflammation were quantified.

RESULTS

Loss of one STAT3 allele in gp130(757F/F) mice reduced the frequency and rate of tumor development because of inhibition of proliferation-induced glandular hyperplasia. There was also a concomitant reduction in the degree of inflammatory infiltration and cytokine and chemokine expression, angiogenesis, and expression of metalloproteinases and growth factors. Antimicrobial treatment of gp130(757F/F) mice slowed tumor growth coincident with reduced macrophage and neutrophil infiltration.

CONCLUSIONS

Activation of STAT3 and the microbial environment are pivotal for gastric tumor initiation and development in the gp130(757F/F) mouse, thus supporting the notion that STAT3 activation may play a role in human gastric cancer development.

REG I expression predicts long-term survival among locally advanced thoracic squamous cell esophageal cancer patients treated with neoadjuvant chemoradiotherapy followed by esophagectomy

BACKGROUND

The prognosis for patients with locally advanced thoracic esophageal cancer is extremely unfavorable. We have been administering neoadjuvant chemoradiotherapy (CRT) followed by esophagectomy to these patients and studying whether REG I expression in untreated endoscopic biopsy specimens is predictive of patient responsiveness to CRT and/or survival after treatment.

METHODS

Between 1992 and 2003, 47 patients with T4 (direct invasion of adjacent organs) thoracic esophageal cancers were administered neoadjuvant CRT followed by esophagectomy. REG I expression was assessed in untreated endoscopic biopsy specimens and correlated with clinical and histological responses and survival in 37 patients who had also undergone curative surgery.

RESULTS

Among the 37 cases that received CRT followed by surgery, the therapeutic response rate for neoadjuvant CRT was 68%, and a complete histological response in resected specimens from the primary lesion was achieved in 8 (22%) patients. These clinical and histological responses to neoadjuvant CRT did not significantly correlate with survival, however. By contrast, 9 patients were judged REG-positive based on analysis of their untreated endoscopic biopsy specimens, and their cumulative survival rate was significantly higher than that of the 28 REG-negative patients (P = 0.0073). Univariate analysis showed REG I expression to be a prognostic factor (P = 0.0386) that increased the risk of death 8.4-fold.

CONCLUSIONS

Evaluation of REG I expression in untreated endoscopic biopsy specimens may provide a basis for new treatments of locally advanced thoracic squamous cell esophageal cancers.

Reg IV activates the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon adenocarcinomas

BACKGROUND & AIMS

Reg IV, a secreted protein and member of the Reg multigene family, is up-regulated in malignancies of the human gastrointestinal tract, including colorectal carcinoma (CRC). However, in vitro signal transduction pathway(s) utilized by Reg IV are not yet known.

METHODS

To determine the signaling pathway(s) responsive to Reg IV, we examined the effects of purified recombinant human Reg IV (rhR4) on HCT116 and HT29 colon adenocarcinoma cells.

RESULTS

Addition of rhR4 to cultures led to a dose-dependent increase in cell number similar to that observed after treatment with epidermal growth factor (EGF). In addition, rhR4 treatment resulted in rapid phosphorylation of EGF receptor at Tyr992 and Tyr1068 and Akt at Thr308 and Ser473. Using luciferase reporter gene assays, we demonstrated that Reg IV signaling through EGF receptor and Akt results in increased activator protein-1 (AP-1) transcription factor activity. Real-time reverse-transcription polymerase chain reaction and Western blot analyses revealed quantitative increases in c-Jun, JunB, JunD, and FosB expression associated with increased AP-1 activity. Electrophoretic mobility shift assay further revealed significant increases in AP-1 binding activity in rhR4-treated cells, with increased supershift in the presence of antibodies to JunB, JunD, and FosB. Furthermore, rhR4 treatments led to the increased expression of Bcl-2, Bcl-XL, survivin, and matrilysin, genes associated with a poor prognosis in advanced CRC.

CONCLUSIONS

Reg IV is a potent activator of the EGF receptor/Akt/AP-1 signaling pathway in CRC. Disruption of Reg signaling may have utility as a therapeutic intervention for human gastrointestinal adenocarcinomas.

Opposite roles of human pancreatitis-associated protein and REG1A expression in hepatocellular carcinoma: association of pancreatitis-associated protein expression with low-stage hepatocellular carcinoma, beta-catenin mutation, and favorable prognosis

PURPOSE

Pancreatitis-associated protein (PAP) and regenerating protein 1 alpha (Reg1A) are up-regulated during the pancreas regeneration. This study is to investigate the clinicopathologic denotation of their expression in hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

PAP and REG1A mRNA levels were measured in 265 surgically removed unifocal primary HCCs using reverse transcription-PCR.

RESULTS

PAP and REG1A mRNAs were detected in 97 (36.6%) and 55 (20.8%) HCCs, respectively, including 46 with coexpression but in none of the 219 nontumorous livers. HCCs with PAP expression correlated with low-stage tumors without evidence of vascular invasion (P = 0.013) but the REG1A expression did not. By a combination analysis, HCCs with PAP expression alone showed the lowest frequency of p53 mutation (P < 0.036), the highest rates of grade 1 and low-stage tumors (P < 0.007 and P < 0.001, respectively), less frequent early tumor recurrence (P = 0.051), and hence a better 5-year survival (P = 0.044) than groups expressing PAP and REG1A, REG1A alone, and neither PAP or REG1A. Besides, PAP expressing HCCs had significantly frequent beta-catenin mutation, regardless of REG1A expression, P < 0.00001. In the subset of HCCs that has no mutations of p53 and beta-catenin but showed PAP expression, coexpression of REG1A and PAP was associated with more frequent vascular invasion than PAP expression alone (P < 0.005).

CONCLUSIONS

These data suggest that PAP expression designate a subset of low-grade, low-stage HCC with frequent beta-catenin mutation and hence more favorable prognosis, whereas further genetic or epigenetic alterations, such as p53 mutation and REG1A expression, lead to more advanced HCCs.

Activation of regenerating gene Reg in rat and human hearts in response to acute stress

Recently, the regenerating gene (Reg) has been documented to play an important role in various regenerating tissues, but it is unknown whether the Reg gene could be activated in the heart. The aim of this study was to reveal the transcriptional activation of Reg in the heart in response to heart stress. We first found REG-1 protein expression in human hearts obtained from autopsied patients who died of myocardial infarction. REG protein was immunohistochemically stained in a fine granular pattern in the cytoplasm of cardiomyocytes. To demonstrate the activation profiles of Reg gene expression in the heart, we quantified the levels of Reg-1 mRNA in rat hearts after coronary artery ligation using real-time RT-PCR. Transient Reg-1 mRNA activation, peaking at 12 h after coronary ligation, was observed mainly in the atria, which was sevenfold higher compared with hearts with pressure overload due to aortic constriction. In contrast, Reg receptor mRNA was expressed intensely in damaged ventricles. Furthermore, Western blot analysis showed the corresponding pattern of Reg protein secretion into the serum after loading, and circulating levels of the protein after myocardial infarction were higher than those after aortic constriction. In conclusion, our results demonstrate for the first time the presence of the Reg/Reg receptor system in damaged hearts. In view of emerging evidence of Reg for tissue regeneration in a variety of tissues/organs, it is proposed that the damaged heart may be a target for Reg action and that Reg may protect against acute heart stress.

REG Ialpha protein may function as a trophic and/or anti-apoptotic factor in the development of gastric cancer

BACKGROUND & AIMS

Although a significant amount of regenerating gene (REG) Ialpha protein is present not only in normal gastric mucosa but also in gastric cancer tissues, its pathophysiologic role in gastric cancer development remains unclear. We investigated REG Ialpha protein expression in early gastric cancers, and examined whether cytokines are responsible for REG Ialpha gene expression and whether REG Ialpha protein has a trophic and/or an antiapoptotic effect on gastric cancer cells.

METHODS

Early gastric cancer specimens were analyzed histologically using immunohistochemistry for REG Ialpha protein and proliferating cell nuclear antigen (PCNA). The effects of cytokines on REG Ialpha promoter activity and its messenger RNA (mRNA) expression in AGS (a kind of gastric cancer cell line) cells were examined by luciferase reporter assay and Northern blot analysis, respectively. Effects of REG Ialpha protein on cell growth and H2O2-induced apoptosis in AGS cells were examined by 3,-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphatase nick-end labeling (TUNEL) assays, respectively.

RESULTS

REG Ialpha-positive early gastric cancers showed a significantly higher PCNA labeling index and more severe inflammatory cell infiltration in adjacent gastric mucosa than the negative cancers. REG Ialpha gene expression and its promoter activity were enhanced by interferon (IFN)-gamma and interleukin (IL)-6. REG Ialpha protein promoted cell growth and cell resistance to H2O2-induced apoptosis in AGS cells. These effects were abolished by concomitant treatment with anti-REG Ialpha antibody. REG Ialpha protein enhanced Akt phosphorylation and Bcl-xL expression in AGS cells.

CONCLUSIONS

REG Ialpha gene is inducible by cytokine stimulation and its gene product may function as a mitogenic and/or an antiapoptotic factor in the development of early gastric cancer.

The multifunctional family of secreted proteins containing a C-type lectin-like domain linked to a short N-terminal peptide

PSP/Lithostathine/PTP/regI, PAP/p23/HIP, reg1L, regIV and "similar to PAP" are the members of a multifunctional family of secreted proteins containing a C-type lectin-like domain linked to a short N-terminal peptide. The expression of this group of proteins is controlled by complex mechanisms, some members being constitutively expressed in certain tissues while, in others, they require activation by several factors. These members have several apparently unrelated biological effects, depending on the member studied and the target cell. These proteins may act as mitogenic, antiapoptotic or anti-inflammatory factors, can regulate cellular adhesion, promote bacterial aggregation, inhibit CaCO3 crystal growth or increase resistance to antitumoral agents. The presence of specific receptors for these proteins is suggested because biological effects were observed after the addition of purified protein to culture media or after systemic administration to animals, whereas other biological effects could be explained by their biochemical capacity to form homo or heteromers or to form insoluble fibrils at physiological pH.

Expression of reg I alpha protein in human gastric cancers

BACKGROUND/AIMS

Although regenerating gene(Reg) I alpha protein has a trophic effect on gastric epithelial cells, it is unclear whether Reg I alpha protein and its receptor are involved in gastric carcinogenesis. Therefore, we investigated the Reg I alpha protein expression in human gastric cancers and assessed its relationship to clinicopathological factors.

METHODS

Sixty-one gastric cancer specimens were examined, using immunohistochemistry, for Reg I alpha protein, p53, and proliferating cell nuclear antigen. The expression of both Reg I alpha and Reg receptor mRNA was examined in seven human gastric cancer cell lines (MKN1, MKN28, MKN45, MKN74, KATOIII, GCIY, and AGS) by reverse transcription-polymerase chain reaction and Northern blot analysis.

RESULTS

Twenty-three (37.7%) of the 61 gastric cancer tissues samples were positive for Reg I alpha protein. The Reg I alpha expression was significantly related to the presence of lymphatic invasion but not to tumor size, tumor stage, Lauren's classification, presence of venous invasion, lymph node metastases, or p53 overexpression. Gastric cancers positive for Reg I alpha protein showed a significantly higher proliferating cell nuclear antigen labeling index than negative ones. The expression of both Reg I alpha and Reg receptor mRNA was detected in all seven gastric cancer cell lines.

CONCLUSION

Reg I alpha protein may play a role in the development of gastric cancers.

Control of expression of the lectin-like protein Reg-1 by gastrin: role of the Rho family GTPase RhoA and a C-rich promoter element

The expression of members of the Reg family of secreted lectin-like proteins is increased in response to stress, inflammation and damage in many tissues. In the stomach, Reg is located in enterochromaffin-like cells, where its expression is stimulated by the gastric hormone gastrin. We have examined the mechanisms by which gastrin stimulates expression of Reg-1. Deletional mutations of 2.1 to 0.1 kb of the rat Reg-1 promoter in a luciferase reporter vector were transiently transfected into gastric cancer AGS-G(R) cells. All promoter fragments tested showed similar relative increases in luciferase expression in response to gastrin (1 nM). The response to gastrin of the smallest (104 bp) construct was 4.2+/-0.4-fold over basal. These responses were reduced by Ro-32-0432, a protein kinase C inhibitor, by C3-transferase, a Clostridium botulinum toxin and a selective inhibitor of the Rho family GTPase RhoA, and by co-transfection with a dominant negative form of RhoA. Co-transfection with a constitutively active form of RhoA stimulated expression 11.6+/-1.7-fold over basal. Mutations through the 104 bp construct identified a C-rich element (C-79CCCTCCC-72) required for responses to gastrin, PKC (protein kinase C) and L63RhoA (the constitutively active form of human RhoA protein containing a glutamine-to-leucine substitution at position 63). EMSAs (electrophoretic-mobility-shift assays) using nuclear extracts of control and gastrin-stimulated AGS-G(R) cells and a probe spanning -86 to -64 bp revealed multiple binding proteins. There was no effect of gastrin on the pattern of binding. Supershift assays indicated that transcription factors Sp1 and Sp3 bound the C-rich sequence. We conclude that gastrin stimulates Reg expression via activation of PKC and RhoA, that a C-rich region (-79 to -72) is critical for the response and that Sp-family transcription factors bind to this region of the promoter.