Expression and localization of Reg IV in human neoplastic and non-neoplastic tissues: Reg IV expression is associated with intestinal and neuroendocrine differentiation in gastric adenocarcinoma

Significance of regenerating islet-derived type IV gene expression in gastroenterological cancers

The regenerating islet-derived members (Reg), a group of small secretory proteins, which are involved in cell proliferation or differentiation in digestive organs, are upregulated in several gastrointestinal cancers, functioning as trophic or antiapoptotic factors. Regenerating islet-derived type IV (RegIV), a member of the Reg gene family, has been reported to be overexpressed in gastroenterological cancers. RegIV overexpression in tumor cells has been associated with carcinogenesis, cell growth, survival and resistance to apoptosis. Cancer tissue expressing RegIV is generally associated with more malignant characteristics than that without such expression, and RegIV is considered a novel prognostic factor as well as diagnostic marker in some gastroenterological cancers. We previously investigated the expression levels of RegIV mRNA of 202 surgical colorectal cancer specimens with quantitative real-time reverse-transcriptase polymerase chain reaction and reported that a higher level of RegIV gene expression was a significant independent predictor of colorectal cancer. The biologic functions of RegIV protein in cancer tissue, associated with carcinogenesis, anti-apoptosis and invasiveness, are being elucidated by molecular investigations using transfection techniques or neutralizing antibodies of RegIV, and the feasibility of antibody therapy targeting RegIV is being assessed. These studies may lead to novel therapeutic strategies for gastroenterological cancers expressing RegIV. This review article summarizes the current information related to biological functions as well as clinical importance of RegIV gene to clarify the significance of RegIV expression in gastroenterological cancers.

Oncogenic reg IV is a novel prognostic marker for glioma patient survival

Aim

The aberrant expression of regenerating islet-derived family member, 4 (Reg IV) has been found in various human cancers. However, the roles of Reg IV gene and its encoding product in human glioma have not been clearly understood. Therefore, the aim of this study was to investigate the clinicopathological significance of Reg IV expression in glioma.

Methods

Reg IV mRNA and protein expression in human gliomas and non-neoplastic brain tissues were respectively detected by real-time quantitative RT-PCR assay, Western blot, and immunohistochemistry. The association of Reg IV immunostaining with clinicopathological factors and prognosis of glioma patients was also statistically analyzed.

Results

Reg IV mRNA and protein expression levels in glioma tissues were both significantly higher than those in the corresponding non-neoplastic brain tissues (both P < 0.001). Additionally, the increased Reg IV immunostaining in glioma tissues was significantly associated with advanced pathological grade (P = 0.008). Reg IV protein up-regulation was also significantly correlated with low Karnofsky performance score (KPS) (P = 0.02). Moreover, the overall survival of patients with high Reg IV protein expression was dramatically shorter than those with low Reg IV protein expression (P < 0.001). Multivariate Cox regression analysis further confirmed that Reg IV expression was an independent prognostic factor for patients with gliomas (P = 0.008).

Conclusions

These convinced evidences suggest for the first time that Reg IV might accelerate disease progression and act as a candidate prognostic marker for gliomas.

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Coordinated expression of REG4 and aldehyde dehydrogenase 1 regulating tumourigenic capacity of diffuse-type gastric carcinoma-initiating cells is inhibited by TGF-β

Aldehyde dehydrogenase 1 (ALDH1) has been shown to serve as a marker for cancer-initiating cells (CICs), but little is known about the regulation of the CIC functions of ALDH1+ cancer cells. We isolated ALDH1+ cells from human diffuse-type gastric carcinoma cells and characterized these cells using an Aldefluor assay. ALDH1+ cells constituted 5-8% of the human diffuse-type gastric carcinoma cells, OCUM-2MLN and HSC-39; were more tumourigenic than ALDH1- cells; and were able to self-renew and generate heterogeneous cell populations. Using gene expression microarray analyses, we identified REG4 (regenerating islet-derived family, member 4) as one of the genes up-regulated in ALDH1+ cells, and thus as a novel marker for ALDH1+ tumour cells. Induced expression of REG4 enhanced the colony-forming ability of OCUM-2MLN cells, while knockdown of REG4 inhibited the tumourigenic potential of ALDH1+ cells. We further found that TGF-β signalling reduces the expression of ALDH1 and REG4, and the size of the ALDH1+ cell population. In human diffuse-type gastric carcinoma tissues, the expression of ALDH1 and REG4 correlated with each other, as assessed by immunohistochemistry, and ALDH1 expression correlated inversely with Smad3 phosphorylation as a measure of TGF-β signalling. These findings illustrate that, in diffuse-type gastric carcinoma, REG4 is up-regulated in ALDH1+ CICs, and that the increased tumourigenic ability of ALDH1+ cells depends on REG4. Moreover, TGF-β down-regulates ALDH1 and REG4 expression, which correlates with a reduction in CIC population size and tumourigenicity. Targeting REG4 in ALDH1+ CICs may provide a novel strategy in the treatment of diffuse-type gastric carcinoma.

Upregulation of HOXA10 in gastric cancer with the intestinal mucin phenotype: reduction during tumor progression and favorable prognosis

Gastric cancer (GC) is one of the most common malignancies worldwide. Better knowledge of the changes in gene expression that occur during gastric carcinogenesis may lead to improvements in diagnosis, treatment and prevention. In this study, we screened for genes upregulated in GC by comparing gene expression profiles from microarray and serial analysis of gene expression and identified the HOXA10 gene. The aim of the present study was to investigate the significance of HOXA10 in GC. Immunohistochemical analysis demonstrated that 221 (30%) of 749 GC cases were positive for HOXA10, whereas HOXA10 was scarcely expressed in non-neoplastic gastric mucosa except in the case of intestinal metaplasia. Next, we analyzed the relationship between HOXA10 expression and clinicopathological characteristics. HOXA10 expression showed a significant inverse correlation with the depth of invasion and was observed more frequently in the differentiated type of GC than in the undifferentiated type of GC. HOXA10 expression was associated with GC with the intestinal mucin phenotype and correlated with CDX2 expression. Furthermore, the prognosis of patients with positive HOXA10 expression was significantly better than in the negative expression cases. 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide and wound healing assay revealed that knockdown of HOXA10 in GC cells by short interfering RNA transfection significantly increased viability and motility relative to the negative control, indicating that HOXA10 expression inhibits cell growth and motility. These results suggest that expression of HOXA10 may be a key regulator for GC with the intestinal mucin phenotype.

Reg IV protein and mRNA expression in different rat organs

The Reg IV gene has been documented in the human colon, small intestine, stomach and pancreas. Expression of the Reg IV in different cell types has been associated with regeneration, cell growth and cell survival, cell adhesion and resistance to apoptosis. Since the distribution of the Reg IV protein in normal rat tissues is unknown, the aim of this study was to reveal the expression of the Reg IV protein in structurally and functionally different rat organs. The expression of Reg IV gene was analyzed by Western blot and reverse transcription-polymerase chain reaction. Immunohistochemistry was used to localize Reg IV protein. Reg IV protein was expressed in pancreas, stomach, small intestine, colon, brain, spleen, kidney and urinary bladder in two-month-old male Wistar rats. In addition, the expression of Reg IV mRNA by reverse transcription-polymerase chain reaction was confirmed. Our study provides detailed information about the expression and localization of Reg IV protein in different rat organs. These findings provide an evidence of Reg IV expression in different rat organs, which may help elucidate a potential role in growth and proliferation of different cells like other members of the Reg family genes which act as growth factors in the different organs.

Regenerating proteins and their expression, regulation and signaling

The regenerating (Reg) protein family comprises C-type lectin-like proteins discovered independently during pancreatitis and pancreatic islet regeneration. However, an increasing number of studies provide evidence of participation of Reg proteins in the proliferation and differentiation of diverse cell types. Moreover, Reg family members are associated with various pathologies, including diabetes and forms of gastrointestinal cancer. These findings have led to the emergence of key roles for Reg proteins as anti-inflammatory, antiapoptotic and mitogenic agents in multiple physiologic and disease contexts. Yet, there are significant gaps in our knowledge regarding the regulation of expression of different Reg genes. In addition, the pathways relaying Reg-triggered signals, their targets and potential cross-talk with other cascades are still largely unknown. In this review, the expression patterns of different Reg members in the pancreas and extrapancreatic tissues are described. Moreover, factors known to modulate Reg levels in different cell types are discussed. Several signaling pathways, which have been implicated in conferring the effects of Reg ligands to date, are also delineated. Further efforts are necessary for elucidating the biological processes underlying the action of Reg proteins and their involvement in various maladies. Better understanding of the function of Reg genes and proteins will be beneficial in the design and development of therapies utilizing or targeting this protein group.

The combined expression of metaplasia biomarkers predicts the prognosis of gastric cancer

BACKGROUND

Our previous study indicated that gene expression profiling of intestinal metaplasia (IM) or spasmolytic polypeptide-expressing metaplasia (SPEM) can identify useful prognostic markers of early-stage gastric cancer, and seven metaplasia biomarkers (MUC13, CDH17, OLFM4, KRT20, LGALS4, MUC5AC, and REG4) were selectively expressed in 17-50% of gastric cancer tissues. We investigated whether the combined expression of these metaplasia biomarkers could predict the prognosis of advanced stage gastric cancer.

METHODS

The expression of seven metaplasia biomarkers was evaluated immunohistochemically using tissue microarrays comprised of 450 gastric cancer patients. The clinicopathologic correlations and the prognostic impact were analyzed according to the expression of multiple biomarkers.

RESULTS

MUC13, CDH17, LGALS4, and REG4 were significant prognostic biomarkers in univariate analysis. No expression of four markers was found in 56 cases (14.2%); 1 marker was seen in 67 cases (17%), 2 in 106 cases (27%), 3 in 101 cases (25.7%), and 4 in 63 cases (16%). Patients in which two or fewer proteins were expressed (group B) showed younger age, undifferentiated or diffuse type cancer, larger tumor size, larger number of metastatic lymph nodes, and more advanced stage than those in which three or more proteins were expressed (group A). In undifferentiated or stage II/III gastric cancer, the prognosis of group B was significantly poorer than that of group A by multivariate analysis.

CONCLUSIONS

The combined loss of expression of multiple metaplasia biomarkers is considered an independent prognostic indicator in undifferentiated or stage II/III gastric cancer.

REGIV as a potential biomarker for peritoneal dissemination in gastric adenocarcinoma

BACKGROUND

This study examined the clinical significance of regenerating islet-derived family member 4 (REGIV) in surgically resected gastric tumors. The potential of REGIV as a biomarker in gastric cancer was also assessed including its predictive value for prognosis and recurrence after surgery.

METHODS

Immunohistochemistry was performed to assess the clinical significance of REGIV expression status in surgically resected specimens. The quantitative genetic diagnostic method, transcription-reverse transcription concerted reaction (TRC) that targeted REGIV mRNA was applied for prediction of peritoneal recurrence in gastric cancer.

RESULTS

Positive immunostaining for REGIV was observed in 85 cases (52.5%), and correlated significantly with diffuse type histopathology (P = 0.001), advanced T stage (P = 0.022), and frequent peritoneal recurrence (P = 0.009). Multivariate analysis identified advanced T stage (P < 0.001) and REGIV expression (P = 0.034) as independent prognostic factors for peritoneal recurrence-free survival. Overexpression of REGIV protein was evident in the majority of peritoneal tumors (93.8%). REGIV mRNA assessed by TRC could be a predictive marker for peritoneal recurrence after curative operation.

CONCLUSIONS

REGIV overexpression is common in primary gastric tumors and a potentially suitable marker of diffuse type histopathology and peritoneal dissemination. Overexpression of REGIV mRNA, assessed by the TRC method, is a potentially suitable marker of peritoneal recurrence after curative resection.

Serum pepsinogen II: a neglected but useful biomarker to differentiate between diseased and normal stomachs

BACKGROUND AND AIM

Serum pepsinogen II (sPGII) is underutilized and considered an inconspicuous biomarker in clinical practice. We refocused on this neglected but novel biomarker and conducted the present study, aiming to elucidate the normal level of sPGII in healthy Chinese patients and to investigate the clinical utility of sPGII for gastric disease screening.

METHODS

In 2008-2009, a total of 2022 participants from northern China were selected and enrolled in the study. sPGII and Helicobacter pylori (H. pylori)-immunoglobulin G were measured with ELISA.

RESULTS

sPGII showed a normal value of 6.6 microg/L in a total of 466 patients with endoscopically- and histologically-normal stomachs. A small sex difference was observed: the average value of sPGII was 7 microg/L and 6 microg/L in males and females, respectively (P < 0.001). In the differentiation between healthy and diseased (endoscopically-diseased stomach or gastritis/atrophic gastritis in endoscopic biopsies) stomach mucosae, the best sPGII cut-off value was 8.25 microg/L (sensitivity 70.6%, specificity 70.8%). In screening the H. pylori seropositivity, the optimum cut-off sPGII value was 10.25 microg/L (sensitivity 71.6%, specificity 70.1%).

CONCLUSIONS

We demonstrated that the mean values of sPGII in a healthy Chinese population are 7 microg/L and 6 microg/L for males and females, respectively. sPGII significantly increases in diseased and H. pylori-infected stomach, and the best sPGII cut-off value is 8.25 microg/L in the differentiation between patients with healthy and diseased stomach mucosae. Furthermore, Chinese patients with sPGII greater than 10.25 microg/L are at greater risk of various H. pylori-related gastropathies, and are therefore prior candidates for gastro-protection therapy.

Identification of RegIV as a novel GLI1 target gene in human pancreatic cancer

BACKGROUND AND AIMS

GLI1 is the key transcriptional factor in the Hedgehog signaling pathway in pancreatic cancer. RegIV is associated with regeneration, and cell growth, survival, adhesion and resistance to apoptosis. We aimed to study RegIV expression in pancreatic cancer and its relationship to GLI1.

METHODS

GLI1 and RegIV expression were evaluated in tumor tissue and adjacent normal tissues of pancreatic cancer patients and 5 pancreatic cancer cell lines by qRT-PCR, Western blot, and immunohistochemistry (IHC), and the correlation between them. The GLI1-shRNA lentiviral vector was constructed and transfected into PANC-1, and lentiviral vector containing the GLI1 expression sequence was constructed and transfected into BxPC-3. GLI1 and RegIV expression were evaluated by qRT-PCR and Western blot. Finally we demonstrated RegIV to be the target of GLI1 by chromatin immunoprecipitation (CHIP) and electrophoretic mobility shift assays (EMSA).

RESULTS

The results of IHC and qRT-PCR showed that RegIV and GLI1 expression was higher in pancreatic cancer tissues versus adjacent normal tissues (p<0.001). RegIV expression correlated with GLI1 expression in these tissues (R = 0.795, p<0.0001). These results were verified for protein (R = 0.939, p = 0.018) and mRNA expression (R = 0.959, p = 0.011) in 5 pancreatic cancer cell lines. RegIV mRNA and protein expression was decreased (94.7±0.3%, 84.1±0.5%; respectively) when GLI1 was knocked down (82.1±3.2%, 76.7±2.2%; respectively) by the RNAi technique. GLI1 overexpression in mRNA and protein level (924.5±5.3%, 362.1±3.5%; respectively) induced RegIV overexpression (729.1±4.3%, 339.0±3.7%; respectively). Moreover, CHIP and EMSA assays showed GLI1 protein bound to RegIV promotor regions (GATCATCCA) in pancreatic cancer cells.

CONCLUSION

GLI1 promotes RegIV transcription by binding to the RegIV gene promoter in pancreatic cancer.

Expression profile of the REG gene family in colorectal carcinoma

Regenerating (REG) gene family belongs to the calcium-dependent lectin gene superfamily and encodes small multifunctional secretory proteins, which might be involved in cell proliferation, differentiation, and carcinogenesis. To clarify REG expression profile in colorectal carcinoma (CRC), the authors examined the expression of REG Iα, Iβ, III, HIP/PAP, and REG IV by immunohistochemistry on tissue microarray. The expression of REG Iα, III, and HIP/PAP was more frequently observed in the CRCs than adjacent non-neoplastic mucosa (p < 0.001), whereas it was the converse for REG Iβ and IV (p < 0.001). The expression of REG Iα, Iβ, III, and HIP/PAP was negatively correlated with the depth of invasion of CRCs (p < 0.05). The REG Iβ and HIP/PAP were less expressed in CRCs with than without venous invasion (p < 0.05). The positive rates of REG Iα and HIP/PAP were significantly higher in CRCs without than with lymph node metastasis (p < 0.05). Mucinous carcinoma more frequently expressed REG IV protein than well- and moderately differentiated ones (p < 0.05). There was a positive relationship between REG Iα, Iβ, III, and HIP/PAP expression (p < 0.05). Survival analysis indicated the REG Iβ or HIP/PAP expression was positively linked to favorable prognosis of carcinoma patients (p < 0.05). This study indicated that aberrant REG expression might be closely linked to the pathogenesis, invasion, or lymph node metastasis of CRCs. REG Iβ and HIP/PAP could be considered reliable markers of favorable prognosis of CRC patients.

Evaluation of REG4 for early diagnosis and prognosis of gastric cancer

We explored the correlation between the development of gastric cancer and the concentration of REG4 and hence the suitability of REG4 as an indicator of the prognosis of patients with GC. Real-time polymerase chain reaction was conducted to detect REG4 messenger RNA expression. The amount of the REG4 protein was measured by immunohistochemistry staining of tissue and enzyme-linked immunosorbent assay of serum. Serum carcinoembryonic antigen and carbohydrate antigen 19-9 concentrations were measured using a commercial automated immunoassay. Real-time polymerase chain reaction results confirmed that REG4 was significantly up-regulated in gastric cancer compared with paired normal mucosa (P < .001). Immunohistochemistry staining revealed that high expression of REG4 correlated with diffuse type, poor differentiation, lymph node metastasis, distant metastasis, and TNM stage III or IV. The mean survival time for patients in the REG4-positive group was significantly less than that in the REG4-negative group (P = .013). The percentage of serum samples that were REG4 positive was 44.0%, which was higher than that for serum carcinoembryonic antigen (P = .039) or carbohydrate antigen 19-9 (P = .012) in TNM stage I and was significantly higher (P = .031) than that in TNM stage II. Thus, REG4 may be not only a prognostic indicator but also a better serum marker than carcinoembryonic antigen and carbohydrate antigen 19-9 for early diagnosis of gastric cancer.

Relationship between RegIV gene expression to outcomes in colorectal cancer

BACKGROUND

Regenerating islet-derived family members (Reg) are superfamily of calcium-dependant lectins that are expressed in the proximal gastrointestinal tract and ectopically at other sites in the setting of tissue injury. The regenerating islet-derived family member 4 (RegIV) gene has been reported in various cancers, associating with diverse functions. This study examined the relation of the relative expression of RegIV gene to clinicopathological factors and outcomes in patients with colorectal cancer (CRC).

METHODS

We studied surgical specimens of cancer tissue and adjacent normal mucosa obtained from 202 patients with untreated CRC. The relative expression levels of RegIV mRNA in cancer and in normal adjacent mucosa were measured by quantitative real-time reverse-transcriptase polymerase chain reaction.

RESULTS

RegIV gene expression was higher in cancer tissue than in adjacent normal mucosa. The multivariate analysis of clinicopathological factors for 5-year overall survival showed a higher level of RegIV gene expression was a significant independent predictor. Overall survival at 5 years differed significantly between patients with high RegIV gene expression and those with low expression.

CONCLUSIONS

Overexpression of the RegIV gene is considered a useful independent predictor of outcomes in patients with CRC.

Serum concentration and expression of Reg IV in patients with esophageal cancer: Age-related elevation of serum Reg IV concentration

Regenerating islet-derived family, member 4 (REG4, which encodes Reg IV) is a marker for cancer and inflammatory bowel disease. This study aimed to investigate the diagnostic utility of Reg IV measurement in sera from esophageal cancer patients. Reg IV expression was examined in 269 esophageal cancer samples by immunostaining and the Reg IV levels in sera were measured from 65 patients with esophageal squamous cell carcinoma (SCC) by enzyme-linked immunosorbent assay. No Reg IV staining was detected in 255 SCC and 4 small cell carcinoma samples, whereas Reg IV was stained in 4 of 10 (40%) adenocarcinoma samples. Serum Reg IV concentration in esophageal SCC patients was significantly higher compared to that of the control subjects (P=0.0003). A significant correlation between serum Reg IV concentration and age was found in control subjects (P<0.0001). When serum Reg IV concentration was analyzed according to age, the distribution of serum Reg IV concentration in patients with esophageal SCC was similar to that of the control subjects. These results suggest that Reg IV expression is highly specific for adenocarcinoma of the esophagus. Further investigation is required to clarify whether Reg IV serves as a serum tumor marker for esophageal cancer.

Selective gene expression by rat gastric corpus epithelium

The gastrointestinal (GI) tract is divided into several segments that have distinct functional properties, largely absorptive. The gastric corpus is the only segment thought of as largely secretory. Microarray hybridization of the gastric corpus mucosal epithelial cells was used to compare gene expression with other segments of the columnar GI tract followed by statistical data subtraction to identify genes selectively expressed by the rat gastric corpus mucosa. This provides a means of identifying less obvious specific functions of the corpus in addition to its secretion-related genes. For example, important properties found by this GI tract comparative transcriptome reflect the energy demand of acid secretion, a role in lipid metabolism, the large variety of resident neuroendocrine cells, responses to damaging agents and transcription factors defining differentiation of its epithelium. In terms of overlap of gastric corpus genes with the rest of the GI tract, the distal small bowel appears to express many of the gastric corpus genes in contrast to proximal small and large bowel. This differential map of gene expression by the gastric corpus epithelium will allow a more detailed description of major properties of the gastric corpus and may lead to the discovery of gastric corpus cell differentiation genes and those mis-regulated in gastric carcinomas.

Immunohistochemical analysis of colorectal cancer with gastric phenotype: claudin-18 is associated with poor prognosis

Claudin-18 plays a key role in constructing tight junctions, and altered claudin-18 expression has been documented in various human malignancies; however, little is known about the biological significance of claudin-18 in colorectal cancer (CRC). The aim of this study is to investigate the significance of claudin-18 expression in CRC and its association with clinicopathological factors. We performed clinicopathological analysis of claudin-18 expression in a total of 569 CRCs by immunohistochemistry. Moreover, we investigated the association between claudin-18 and various markers including gastric/intestinal phenotype (MUC5AC, MUC6, MUC2 and CD10), CDX2, claudin-3, claudin-4, p53 and Ki-67. Claudin-18 expression was detected in 21 of the 569 CRCs (4%) and was seen exclusively on the cell membrane. Positive expression of claudin-18 showed a significant correlation with positive expression of MUC5AC (P < 0.0001) and negative expression of CDX2 (P= 0.0013). The prognosis of patients with positive claudin-18 expression was significantly poorer than in negative cases (P= 0.0106). Multivariate analysis revealed that T grade, M grade and claudin-18 expression were independent predictors of survival in patients with CRC. We revealed that claudin-18 expression correlates with poor survival in patients with CRC and is associated with the gastric phenotype.

Immunostaining of gastric cancer with neuroendocrine differentiation: Reg IV-positive neuroendocrine cells are associated with gastrin, serotonin, pancreatic polypeptide and somatostatin

We previously reported that Reg IV is associated with neuroendocrine (NE) differentiation in gastric cancers. The aim was to examine which NE hormone products are related to Reg IV-positive NE cells and their roles in gastric cancers. In the present study, we performed immunohistochemical analysis in a tissue microarray (TMA) of a consecutive series of 630 cases with ten different antibodies, including chromogranin A, synaptophysin and neural cell adhesion molecule (NCAM) as NE differentiation markers, and gastrin, serotonin, calcitonin, gastrin-releasing peptide (GRP), pancreatic polypeptide (PP), somatostatin and glucagon as NE hormones. In 630 cases, we identified 205 (33%) with NE differentiation and 147 (23%) positive for Reg IV. Reg IV-positive cases showed NE differentiation more frequently than Reg IV-negative cases (P < 0.0001). In 205 cases with NE differentiation, Reg IV-positive cases expressed serotonin (P= 0.0032) and somatostatin (P= 0.036) more frequently than Reg IV-negative cases. Double immunofluorescence staining revealed co-expression of Reg IV with gastrin, serotonin and PP. These results indicate that Reg IV might be a mediating factor of several NE hormones.

RegIV expression showing specificity to gastrointestinal tract and its potential role in diagnosing digestive tract neuroendocrine tumor

Regenerating gene IV (RegIV), a member of the regenerating gene family discovered in 2001, has been found to be involved in malignancy in several different organs including the stomach, colorectum, pancreas and prostate, but the overall expression profile of RegIV has not been reported. To learn more about RegIV, we evaluated its distribution by immunohistochemistry (IHC) in a total of 360 samples including 24 types of normal tissue, 40 benign and malignant lesions, and 18 neuroendocrine tumors. We found that in normal tissues, in addition to its relative specificity for the gastrointestinal tract, RegIV was detected in the adrenal gland and mammary gland. Among all the malignancies of various histological types under evaluation, RegIV was found mostly in adenocarcinomas. Studies on additional sets of colorectal tumor samples showed that RegIV expression was predominant in colorectal adenoma (87.5%) and peritumoral tissue (100%) but not in cancer tissue (30.8%). Among neuroendocrine tumors, RegIV had a relatively restricted expression to those of digestive system.

Gene expression profiling of metaplastic lineages identifies CDH17 as a prognostic marker in early stage gastric cancer

BACKGROUND & AIMS

Intestinal metaplasia (IM) and spasmolytic polypeptide-expressing metaplasia (SPEM) are precursors to gastric carcinogenesis. We sought to identify molecular biomarkers of gastric metaplasias and gastric cancer by gene expression profiling of metaplastic lesions from patients.

METHODS

Complementary DNA microarray analysis was performed on IM and SPEM cells isolated from patient samples using laser capture microdissection. Up-regulated transcripts in metaplastic lesions were confirmed by immunostaining analysis in IM, SPEM, and gastric cancer tissues. Proteins that were highly expressed specifically in gastric cancer tissues were analyzed for their association with survival in a test set (n = 450) and a validation set (n = 502) of samples from gastric cancer patients.

RESULTS

Compared with normal chief cells, 858 genes were differentially expressed in IM or SPEM samples. Immunostaining was detected for 12 proteins, including 3 new markers of IM (ACE2, LGALS4, AKR1B10) and 3 of SPEM (OLFM4, LYZ, DPCR1). Of 13 proteins expressed in IM or SPEM, 8 were expressed by 17%-50% of human gastric cancer tissues (MUC13, OLFM4, CDH17, KRT20, MUC5AC, LGALS4, AKR1B10, REG4). Expression of CDH17 or MUC13 correlated with patient survival in the test and validation sets. Multivariate analysis showed that CDH17 was an independent prognostic factor in patients with stage I or node-negative disease.

CONCLUSIONS

We identified several novel biomarkers for IM, SPEM, and gastric cancer using gene expression profiling of human metaplastic lesions. Expression of CDH17 and MUC13 was up-regulated in gastric cancer tissues. CDH17 is a promising prognostic marker for early stage gastric cancer.

RegIV potentiates colorectal carcinoma cell migration and invasion via its CRD domain

The RegIV gene is differentially expressed in cancer and noncancerous cells. In this study, we investigated the role of RegIV and its CRD domain in the invasion and migration of human colorectal carcinoma LoVo cells. Recombinant plasmids, pcDNA3.1-RegIV and pcDNA3.1-RegIV CRD, were constructed and transfected into LoVo cells. The in vivo RegIV and RegIV CRD mRNA and protein levels were then analyzed by reverse transcriptase-polymerase chain reaction and immunocytochemistry, respectively. Cell proliferation was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and flat plate colony-forming assays, and apoptosis was measured by flow cytometry. Cell migration and invasion were assessed with a Transwell chamber. A high level of RegIV and RegIV carbohydrate-recognition domain (CRD) expression was demonstrated in RegIV and RegIV CRD-transfected cells. There were no differences in cell proliferation, colony formation, and apoptosis between the LoVo/RegIV and untreated LoVo cells (P > 0.05). However, the LoVo/RegIV cells, but not LoVo/RegIV CRD cells, displayed greater migration and invasion abilities compared to the empty vector and untreated LoVo cells. The migrated cell numbers of the LoVo/RegIV, LoVo/RegIV CRD, LoVo/empty vector, and control LoVo groups were 247.00 +/- 10.61, 146.27 +/- 6.81, 151.16 +/- 7.18, and 149.65 +/- 6.53 cells per field, respectively (P < 0.05). The invasion cell numbers of the four groups were 57.00 +/- 3.00, 31.53 +/- 2.72, 30.3 +/- 2.07, and 32.16 +/- 2.30 cells per field, respectively. RegIV enhances LoVo cell migration and invasion, and its CRD domain is critical for these effects.

Loss of RegI in conjunction with gastrin deficiency in mice facilitates efficient gastric ulcer healing but is dispensable for hyperplasia and tumourigenesis

RegI (Regenerating islet derived-1) was originally characterized as a growth factor involved in pancreatic islet cell regeneration. It is also considered a gastrointestinal mitogen as its expression is increased during pathologies involving aberrant cell proliferation that can lead to neoplasia. However, the absolute requirement for RegI to directly stimulate gastric mucosal cell proliferation in vivo requires further investigation. We used RegI-deficient mice to determine the requirement for RegI in normal gastric mucosal development, wound healing, hyperplasia and tumourigenesis. We found that epithelial repair of acetic acid ulcers in compound mutant RegI/gastrin-deficient mice was significantly reduced compared to wild type, RegI-deficient or gastrin-deficient mice. In contrast, RegI was dispensable for normal gastric mucosal development, hyperplasia in HKbeta-deficient mice and tumourigenesis in gp130(F/F) mice. Although RegI was not required for proliferation in these pathological models, expression of multiple Reg family members were increased during gp130(F/F) tumourigenesis. Interestingly, loss of RegI in gp130(F/F) mice resulted in decreased expression of other Reg family members. Our results indicate that RegI and gastrin may synergistically regulate gastric mucosal proliferation during certain pathological settings like wound healing while gastric epithelial proliferation in other pathologies may require coordinated expression of multiple Reg genes.

Serum olfactomedin 4 (GW112, hGC-1) in combination with Reg IV is a highly sensitive biomarker for gastric cancer patients

Gastric cancer (GC) is 1 of the most common human cancers. Early detection remains the most promising approach to improving long-term survival of patients with GC. We previously performed Serial Analysis of Gene Expression (SAGE) on 4 primary GCs and identified several GC-specific genes including Reg IV. Of these genes, olfactomedin 4 (OLFM4, also known as GW112 or hGC-1) is a candidate gene for cancer-specific expression. In this study, we examined the expression of olfactomedin 4 in human GC by immunohistochemistry. We also assessed serum olfactomedin 4 levels in GC patients by enzyme-linked immunosorbent assay. 94 (56%) of 167 GC cases were positive for olfactomedin 4 by immunostaining. Olfactomedin 4 staining was observed more frequently in stage I/II cases than in stage III/IV cases. The serum olfactomedin 4 concentration in presurgical GC patients (n = 123, mean +/- SE, 36.3 +/- 3.5 ng/mL) was significantly higher than that in healthy individuals (n = 76, 16.6 +/- 1.6 ng/mL). In patients with stage I GC, the sensitivity of serum olfactomedin 4 (25%) and Reg IV (35%) was superior to that of CA19-9 (5%) or CEA (3%). Furthermore, in patients with stage I GC, the combination of olfactomedin 4 and Reg IV elevated the diagnostic sensitivity to 52%. These results suggest that serum olfactomedin 4 is a useful marker for GC and its measurement alone or in combination with Reg IV has utility in the early detection of GC.

Serum REG4 level is a predictive biomarker for the response to preoperative chemoradiotherapy in patients with pancreatic cancer

OBJECTIVES

Preoperative chemoradiotherapy is one of the key strategies for the improvement of survival in pancreatic cancer; however, no method to predict the response has yet been established. The aim of this study was to prospectively evaluate the predictive value of REG4, a new member of the regenerating (REG) islet-derived family of proteins.

METHODS

Stably REG4-expressing cells were established from a pancreatic cancer cell line and exposed in vitro to gamma-ray or gemcitabine to investigate the relevance of REG4 to the resistance to chemotherapy or radiotherapy. In 23 patients with resectable pancreatic cancer, the serum concentration of REG4 was measured before preoperative chemoradiotherapy, and the histologic response was evaluated after the surgery.

RESULTS

A 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and fluorescence activated cell scanning (FACS) revealed that REG4-overexpressing cells were resistant to gamma-radiation but showed a modest resistance to gemcitabine. The patients with a higher REG4 level, but not carcinoembryonic antigen or CA-19-9, showed an unfavorable histologic response to chemoradiotherapy (Spearman, rho = 0.439, P = 0.039). The patients showing a higher REG4 level experienced local recurrence postoperatively.

CONCLUSIONS

These data demonstrated in vitro and in vivo that REG4 protein overexpression was associated with an unfavorable response to preoperative chemoradiotherapy. REG4 can clinically be used as a predictive biomarker.

The role of Reg IV gene and its encoding product in gastric carcinogenesis

Although the biologic function of Reg IV is poorly understood, it has been reported that Reg IV is a potent activator of the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon cancer cells and closely linked with the inhibition of apoptosis. To clarify the role of Reg IV in gastric carcinogenesis and subsequent progression, we examined its expression by immunohistochemistry and in situ hybridization on tissue microarray containing gastric carcinoma, adjacent nonneoplastic mucosa, adenoma, intestinal metaplasia, or gastritis. Gastric carcinoma cell lines (MKN28, AGS, MKN45, KATO-III, and HGC-27) were studied for Reg IV expression by Western blot and reverse transcriptase-polymerase chain reaction followed by sequencing. Frozen samples of gastric carcinoma and adjacent nonneoplastic mucosa were subjected to Western blot, and patient serum, to enzyme-linked immunosorbent assay for Reg IV. Gastric carcinoma cell lines showed different levels of Reg IV mRNA and its encoding protein. The Reg IV protein expression was gradually decreased from intestinal metaplasia, adenoma, and carcinoma to gastritis (P < .05). The positive rate of its mRNA was higher in intestinal metaplasia than carcinoma or nonneoplastic mucosa (P < .05). Elevated serum Reg IV level in gastric carcinoma patients was detected in comparison with that in health individuals (P < .05). Reg IV expression was significantly correlated with the MUC-2 and MUC-5AC expression (P < .05). Among histologic subtypes of the World Health Organization, signet ring cell carcinoma more frequently expressed Reg IV than the others (P < .05), whereas it is the converse for the poorly differentiated group (P < .05). Our study indicated that Reg IV expression experienced up-regulation in gastric intestinal metaplasia and adenoma and then down-regulation with malignant transformation of gastric epithelial cells. It was suggested that Reg IV expression should be considered as a good biomarker for gastric precancerous lesions and was especially related to the histogenic pathway of signet ring cell carcinoma.

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.

Advances in RegIV and alimentary system neoplasms

RegIV, a novel member of regenerating gene family, is located at 1p12-13.1, encoding a 17-kDa secreted protein, which is constitutively expressed in the epithelium of normal pancreas and gastrointestinal tract, whereas the expression is up-regulated in inflammatory or neoplastic tissues. RegIV is involved in the carcinogenesis, progression, metastasis and drug resistance of alimentary system neoplasms, and is thought to be useful to make a forecast of the prognosis. It may serve as a new important target for the prevention, diagnosis and treatment of gastrointestinal neoplasms.

Transcriptome dissection of gastric cancer: identification of novel diagnostic and therapeutic targets from pathology specimens

Gastric cancer is the fourth most common malignancy in the world, and mortality due to gastric cancer is second only to that from lung cancer. 'Transcriptome dissection' is a detailed analysis of the entire expressed transcripts from a cancer, for the purpose of understanding the precise molecular mechanism of pathogenesis. Serial analysis of gene expression (SAGE) is a suitable technique for performing transcriptome dissection. Gastric cancers of different stages and histology were analyzed on SAGE, and one of the largest gastric cancer SAGE libraries in the world was created (GEO accession number GSE 545). Through SAGE, many candidate genes have been identified as potential diagnostic and therapeutic targets for the treatment of gastric cancer. Regenerating islet-derived family, member 4 (Reg IV) participated in 5-fluorouracil (5-FU) resistance and peritoneal metastasis, and its expression was associated with an intestinal phenotype of gastric cancer and with endocrine differentiation. GW112 expression correlated with advanced tumor stage. Measurement of Reg IV and GW112 levels in sera indicated a sensitivity of 57% for detection of cancer. SPC18 participated in tumor growth and invasion through transforming tumor growth factor-alpha upregulation. Palate, lung, and nasal epithelium carcinoma-associated protein (PLUNC) was a useful marker for gastric hepatoid adenocarcinoma. Expression of SOX9, HOXA10, CDH17, and loss of claudin-18 expression were associated with an intestinal phenotype of gastric cancer. Information obtained from transcriptome dissection greatly contributes to diagnosis and treatment of gastric cancer.

REG4 is associated with carcinogenesis in the 'intestinal' pathway of intraductal papillary mucinous neoplasms

Subclassification of intraductal papillary mucinous neoplasms of the pancreas (IPMNs), based on morphological features and immunohistochemical profiles, has been proposed. Intestinal-type IPMNs frequently show moderate to severe dysplasia. Regenerating islet-derived family, member 4 (REG4) is associated with the adenoma-carcinoma sequence in colon cancer and it is also associated with intestinal phenotype. Therefore, to identify REG4 expression in IPMNs may be helpful to detect high-grade IPMNs. We also investigated REG4 expression and CDX2 expression in IPMNs. To investigate the expressions of REG4 and CDX2 in IPMNs and in invasive ductal adenocarcinoma derived from IPMN, we used immunohistochemical staining and microdissection-based quantitative real-time reverse transcription-polymerase chain reaction. Among 125 IPMNs, 43 (34%) were positive for REG4 and most of the intestinal-type IPMNs showed its expression (35/38). The positive ratio of REG4 expression in colloid carcinoma (5/7) was significantly higher than that in tubular carcinoma (1/17; P=0.003). Most of CDX2-positive cases (31/33) expressed REG4 protein, whereas only 12 of 92 CDX2-negative cases did (P<0.001). The levels of REG4 mRNA in intestinal-type IPMN were significantly higher compared to those in gastric-type IPMN or to normal pancreatic ductal epithelium (P=0.005, P=0.004, respectively). REG4 expression was observed more frequently in borderline lesions (14/28) and carcinoma (21/45) compared to adenoma (8/52). Using the Ki-67 labeling index, REG4 expression was significantly correlated with proliferative activity in borderline lesions. We conclude that REG4 is involved in the 'intestinal' pathway of carcinogenesis in IPMN.

Influence of down-regulation of RegⅣ expression by small interfering RNA on proliferation and apoptosis of gastric cancer cells

AIM: To investigate RegⅣ expression level in human gastric cancer cell lines and the effect of RNA interfering of RegⅣ on proliferation and apoptosis of gastric cancer cells.

METHODS: The expression levels of RegⅣ in nine gastric cancer cell lines were examined by real time PCR, and 3 small interfering RNA (siRNA1, siRNA2, siRNA3) targeting RegⅣ were designed and transfected into gastric cancer cell lines. The changes of RegⅣ mRNA expression level after siRNA interfering were detected by real time PCR. The proliferation was assayed by CCK-8 method. Flow cytometry was used to detect apoptosis of gastric cancer cells.

RESULTS: Compared with gastric mucosa cell line GES-1, the expression level of RegⅣ in gastric cancer cells was 5-fold or higher except MKN-45 and SNU-1. The expression level of RegⅣ in SNU-16 was the highest and was several thousand-fold higher than that in GES-1. SNU-16 was used for siRNA experiment. Three siRNAs showed notably down-regulated expression of RegⅣ mRNA levels with inhibitory rate of 79.3%, 77.4% and 60.4%, respectively in comparison with that in control group. So siRNA1 was used to do cell proliferation assay. After 96 hours' and 120 hours' transfection of siRNA1, the proliferation of SNU-16 cell significantly decreased compared with the control group (P = 0.0057, 0.0173, respectively). The results of flow cytometry revealed that 72 h after transfection with siRNA1, the apoptosis rate of SNU-16 significantly increased.

CONCLUSION: Interfering and down-regulating RegⅣ gene can inhibit proliferation and promote apoptosis of gastric cancer cells, indicating that RegⅣ gene is probably a target for gastric cancer gene therapy.

Reg IV enhances peritoneal metastasis in gastric carcinomas

OBJECTIVES

The role of Regenerating (Reg) IV on peritoneal metastasis was examined in gastric cancer using.

MATERIAL AND METHODS

Reg IV-transfected human gastric cancer cells (MKN28-R1, MKN28-R2, TMK1-R1), control transfectants (MKN28-R0, TMK1-R0), and REG4-knocked down MKN45 cells were examined in in vitro and in nude mice peritoneal metastasis models.

RESULTS AND DISCUSSION

Increase of expression and secretion of Reg IV, and levels of BCL-2, BCL-XL,survivin, phosphorylated AKT, and phosphorylated EGFR, and decrease of nitric oxide-induced apoptosis were found in Reg IV-transfectants, whereas those were abrogated in the knockdown cells. In mice models, increased number and size of peritoneal tumors and decreased apoptosis were found in Reg IV-transfectants, whereas those were abrogated by the knockdown cells. Mice survivals were worsened in Reg IV-transfectants-inoculated mice, but were improved in Reg IV-knockdown cell-inoculated mice. Levels of Reg IV protein in peritoneal lavage fluids increased in Reg IV-transfectants inoculated mice, but decreased in Reg IV-knockdown cell inoculated mice. In metastasized human gastric cancers, Reg IV positivity in peritoneum-metastasis cases was higher than those in negative cases. Reg IV was detected in peritoneal lavage fluids from human gastric cancer patients, in whose lavages keratin mRNA was detected by reverse transcriptase-polymerase chain reaction. Collectively, Reg IV might accelerate peritoneal metastasis in gastric cancer. Reg IV in lavage fluids might be a good marker for peritoneal metastasis.

Reg IV expression is associated with cell growth and prognosis of adenoid cystic carcinoma in the salivary gland

AIMS

Regenerating islet-derived family, member 4 (Reg IV) is associated with the progression of various cancers. The aim was to examine Reg IV expression in adenoid cystic carcinomas (ACCs) in salivary glands.

METHODS AND RESULTS

Reg IV expression was detected by immunohistochemistry and compared with clinicopathological parameters. Expression of phosphorylated epidermal growth factor receptor (pEGFR), phosphorylated AKT (pAKT) and MUC2 was examined by immunohistochemistry. Reg IV function was assessed with Reg IV antisense S-oligodeoxynucleotides (AS) in ACC3 human ACC cells. Reg IV was expressed by salivary duct epithelia and acinus myoepithelia, but not in squamous epithelia. Reg IV expression was found in 41% (17/41) of ACCs, but in none of 40 oral squamous cell carcinomas (OSCCs) and was associated with nodal metastasis (P = 0.047) and poor prognosis (P = 0.012) in ACCs. Reg IV expression was associated with pEGFR (14/17, 82%) in Reg IV+ ACCs, but had no relationship with pAKT or MUC2 expression in ACCs. Cell growth was inhibited by AS treatment in Reg IV+ ACC3 cells, but not in HSC-4 OSCC cells, whereas in vitro invasion of neither cell types was affected by AS treatment.

CONCLUSIONS

These results suggest that Reg IV might accelerate cell growth and disease progression of ACCs.

Abnormal growth factor/cytokine network in gastric cancer

Gastric cancer cells express a broad spectrum of the growth factor/cytokine receptor systems that organize the complex interaction between cancer cells and stromal cells in tumor microenvironment, which confers cell growth, apoptosis, morphogenesis, angiogenesis, progression and metastasis. However, these abnormal growth factor/cytokine networks differ in the two histological types of gastric cancer. Importantly, activation of nuclear factor-kB pathway by Helicobacter pylori infection may act as a key player for induction of growth factor/cytokine networks in gastritis and pathogenesis of gastric cancer. Better understanding of these events will no doubt provide new approaches for biomarkers of diagnosis and effective therapeutic targeting of gastric cancer.

Advances in regenerating gene family and digestive system neoplasms

Since the first member of regenerating gene (Reg) family was discovered in 1988, it has been verified that regenerating genes play important roles in diabetes, inflammation and injury, and digestive system tumors. Now, more members of Reg family have been cloned. With further investigations, the great role of Reg family, especially Reg IV, in digestive system neoplasms has attracted more and more attention.

Immunohistochemical staining of Reg IV and claudin-18 is useful in the diagnosis of gastrointestinal signet ring cell carcinoma

Signet-ring cell carcinoma (SRCC) is a unique subtype of adenocarcinoma that is characterized by abundant intracellular mucin accumulation and a crescent-shaped nucleus displaced toward one end of the cell. Identification of an SRCC's primary site is important for better planning of patient management because the treatment and prognosis differs markedly depending on the origin of the SRCC. In the present study, we analyzed the immunohistochemical characteristics of 94 cases of SRCC, including 21 cases of gastric SRCC, 16 of colorectal SRCC, 10 of breast SRCC, and 47 of pulmonary SRCC, with antibodies against Reg IV and claudin-18, which we previously identified as gastric cancer-related genes. We also tested known markers cytokeratin 7, cytokeratin 20, MUC2, MUC5AC, caudal-related homeobox gene 2 (CDX2), thyroid transcription factor-1, mammaglobin, gross cystic disease fluid protein 15, and estrogen receptor. All 21 cases of gastric SRCC and 16 cases of colorectal SRCC were positive for Reg IV, and the remaining SRCCs were negative. Eighteen of 21 (86%) gastric SRCCs and 6 of 16 (38%) colorectal SRCCs were positive for claudin-18, whereas another SRCCs were negative. In conclusion, Reg IV staining and claudin-18 staining can aid in diagnosis of gastrointestinal SRCC.

Reg IV is an independent prognostic factor for relapse in patients with clinically localized prostate cancer

Regenerating islet-derived family, member 4 (REG4, which encodes Reg IV) is a candidate marker for cancer and inflammatory bowel disease. We investigated the potential prognostic role of Reg IV immunostaining in clinically localized prostate cancer (PCa) after radical prostatectomy. Immunohistochemical staining of Reg IV was performed in 98 clinically localized PCa tumors obtained during curative radical prostatectomy. Intestinal and neuroendocrine differentiation was investigated by MUC2 and chromogranin A immunostaining, respectively. The prognostic significance of immunohistochemical staining for these factors on prostate-specific antigen (PSA)-associated recurrence was assessed by Kaplan-Meier analysis and a Cox regression model. Phosphorylation of the epidermal growth factor receptor (EGFR) by Reg IV was analyzed by Western blot. In total, 14 (14%) of the 98 PCa cases were positive for Reg IV staining. Reg IV positivity was observed frequently in association with MUC2 (P = 0.0182) and chromogranin A positivity (P = 0.0012). Univariate analysis revealed that Reg IV staining (P = 0.0004), chromogranin A staining (P = 0.0494), Gleason score (P < 0.0001) and preoperative PSA concentration (P = 0.0167) were significant prognostic factors for relapse-free survival. Multivariate analysis indicated that Reg IV staining (P = 0.0312), Gleason score (P = 0.0014) and preoperative PSA concentration (P = 0.0357) were independent predictors of relapse-free survival. In the LNCaP cell line, EGFR phosphorylation was induced by the addition of Reg IV-conditioned medium. These results suggest that Reg IV expression is an independent prognostic indicator of relapse after radical prostatectomy.

Reg genes are CCK2 receptor targets in ElasCCK2 mice pancreas

We previously demonstrated that expression of the gastrin receptor, CCK2R, in pancreatic acini of transgenic ElasCCK2 mice induced alteration of acinar morphology and differentiation, increased sensitivity to a carcinogen and development of preneoplastic lesions and tumours. Reg proteins are suggested to be involved in pancreatic cancer and in regeneration of endocrine pancreas. Reg I gene is a known target of gastrin. We examined whether an expression of CCK2R in the pancreatic acini of ElasCCK2 mice is linked to induction of Reg proteins expression. We analyzed Reg expression by Western-blot and immunohistochemistry in pancreas from ElasCCK2 and control mice. Islet neogenesis, glucose homeostasis, insulin secretion and content were also evaluated. Reg I is exclusively produced in acini in ElasCCK2 and control mice. In tumoral pancreas, Reg I and Reg III proteins are expressed in duct-like cells in preneoplastic lesions or in the periphery of tumours and in adjacent acini. The expression of Reg III proteins is increased in ElasCCK2 pancreas before the development of preneoplastic lesions in a subpopulation of islet cells and in small islet-like cell clusters dispersed within the acinar tissue. Several criteria of an enhanced neogenesis are fulfilled in ElasCCK2 pancreas. Moreover, ElasCCK2 mice have an improved response to glucose load, an increased insulin secretion and a doubling of insulin content compared to control mice. We show that Reg proteins are targets of CCK2R activation and are induced during early steps of carcinogenesis in ElasCCK2 mice pancreas. Alterations of exocrine tissue homeostasis in ElasCCK2 pancreas concomitantly activate regenerative responses of the endocrine pancreas possibly linked to paracrine actions of Reg III proteins.

Serum concentration of Reg IV in patients with colorectal cancer: overexpression and high serum levels of Reg IV are associated with liver metastasis

OBJECTIVE

Regenerating islet-derived family, member 4 (regenerating gene type IV, Reg IV) is overexpressed in colorectal cancer (CRC). The aim of this study was to investigate the diagnostic utility of Reg IV determination in sera from patients with CRC.

METHODS

We examined the expression and distribution of Reg IV in CRC by immunohistochemistry and determined Reg IV levels in sera from patients with CRC by enzyme-linked immunosorbent assay.

RESULTS

Immunostaining revealed that 23 of 80 (29%) CRC cases were positive for Reg IV. CRC cases with metastatic recurrence in the liver showed more frequently Reg IV staining than those without (p = 0.0102). Patients with CRC showing Reg IV staining had a significantly worse survival than those without Reg IV staining (p = 0.0117). Preoperatively, serum Reg IV concentrations were not elevated in CRC patients at stage 0-III, being in contrast to the significantly increased preoperative levels in stage IV CRC patients with liver metastasis.

CONCLUSION

These results suggest that Reg IV is a prognosticator for poor survival. Serum Reg IV concentration may predict CRC recurrence in the liver.

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 REG IV gene in ulcerative colitis

The regenerating gene (REG) IV gene was isolated from a cDNA library of ulcerative colitis (UC) tissues. However, its role in the pathophysiology of UC and subsequent development of colitic cancer is still unclear. We investigated the expression of the REG IV gene in UC and colitic cancer tissues and examined whether cytokines or growth factors are responsible for REG IV gene expression and whether REG IV gene induction affects cell growth and apoptosis in colon cancer cells. The expressions of REG IV and growth factor genes in UC tissues were analyzed by real time reverse transcription-polymerase chain reaction. The effects of cytokines and growth factors on REG IV gene expression were examined in SW403 cells by Northern blot analysis. The effects of REG IV gene induction on cell growth and H(2)O(2)-induced apoptosis were examined in DLD-1 cells by MTT and TUNEL assays, respectively. REG IV mRNA was strongly expressed in inflamed epithelium and in dysplasias and cancerous lesions in UC tissues. The level of REG IV mRNA expression was correlated with that of basic fibroblast growth factor (bFGF) as well as hepatocyte growth factor (HGF) mRNA expression in UC tissues. The REG IV gene expression in SW403 colon cancer cells was enhanced by stimulation with transforming growth factor-alpha, epidermal growth factor, bFGF, and HGF. REG IV gene induction promoted cell growth and conferred resistance to H(2)O(2)-induced apoptosis in DLD-1 cells. The REG IV gene is inducible by growth factors and may function as a growth promoting and/or an antiapoptotic factor in the pathophysiology of UC.

Reg IV is a serum biomarker for gastric cancer patients and predicts response to 5-fluorouracil-based chemotherapy

Regenerating gene family, member 4 (Reg IV), a secreted protein, is overexpressed in several cancers, including gastric cancer (GC). In the present study, we measured Reg IV levels in sera from patients with GC by enzyme-linked immunosorbent assay. We also examined the effect of forced Reg IV expression on the apoptotic susceptibility to 5-fluorouracil (5-FU). Forced expression of Reg IV inhibited 5-FU-induced apoptosis. Induction of Bcl-2 and dihydropyrimidine dehydrogenase was involved in inhibition of apoptosis. Among 36 GC patients treated with a combination chemotherapy of low-dose 5-FU and cisplatin, all 14 Reg IV-positive patients showed no change or disease progression. The serum Reg IV concentration was similar between healthy individuals (mean+/-s.e., 0.52+/-0.05 ng/ml) and patients with chronic-active gastritis (0.36+/-0.09 ng/ml). However, the serum Reg IV concentration in presurgical GC patients was significantly elevated (1.96+/-0.17 ng/ml), even at stage I. The diagnostic sensitivity of serum Reg IV (36.1%) was superior to that of serum carcinoembryonic antigen (11.5%) or carbohydrate antigen 19-9 (13.1%). These results indicate that expression of Reg IV is a marker for prediction of resistance to 5-FU-based chemotherapy in patients with GC. Serum Reg IV represents a novel biomarker for GC.

Down-regulation of the claudin-18 gene, identified through serial analysis of gene expression data analysis, in gastric cancer with an intestinal phenotype

Gastric cancer (GC) is one of the most common malignancies worldwide. Genes whose expression is down-regulated in GC may be tumour suppressor genes. In the present study, genes with decreased expression in GC were screened for by serial analysis of gene expression (SAGE) data analysis and reverse transcription (RT)-polymerase chain reaction (PCR), and CLDN18 (encoding claudin-18) was identified. Quantitative RT-PCR revealed that expression of CLDN18 was down-regulated in 13 (56.5%) of 23 GCs. Immunostaining showed that normal gastric mucosa and Paneth cells of the duodenum expressed claudin-18 on cell membranes. Expression of claudin-18 was reduced in several intestinal metaplasias of the stomach. Of 20 samples of gastric adenoma, 18 (90.0%) showed decreased claudin-18 expression. Down-regulation of claudin-18 was observed in 84 of 146 GCs (57.5%) and correlated with poor survival in 65 advanced GCs (p = 0.0346). In addition, expression of the gastric and intestinal phenotypes of GC was examined by immunostaining for MUC5AC, MUC6, MUC2, and CD10. Of 38 GCs showing only the intestinal phenotype, down-regulation of claudin-18 was observed in 28 (73.7%), whereas in the remaining 108 GC cases, down-regulation of claudin-18 was observed in 56 (51.9%) (p = 0.0224). These results indicate that claudin-18 is a good marker of poor survival in GC. Down-regulation of claudin-18 may be involved in GCs with an intestinal phenotype, and may be an early event in gastric carcinogenesis.

Systematic search for gastric cancer-specific genes based on SAGE data: melanoma inhibitory activity and matrix metalloproteinase-10 are novel prognostic factors in patients with gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide. Genes expressed only in cancer tissue will be useful molecular markers for diagnosis and may also be good therapeutic targets. However, little is known about cancer-specific genes, at least in GC. In this study, we searched for GC-specific genes by serial analysis of gene expression (SAGE) data analysis and quantitative reverse transcription (RT)-PCR. Comparing GC SAGE libraries with those of various normal tissues in the SAGEmap database, we identified 54 candidate GC-specific genes. Quantitative RT-PCR analysis of these candidates revealed that APin protein (APIN), taxol resistance-associated gene 3 (TRAG3), cytochrome P450, family 2, subfamily W, polypeptide 1 (CYP2W1), melanoma inhibitory activity (MIA), matrix metalloproteinase-10 (MMP-10), dickkopf homolog 4 (DKK4), GW112, regenerating islet-derived family, member 4 (REGIV), and HORMA domain-containing 1 (HORMAD1) were expressed much more highly in GC than in 14 kinds of normal tissues. Immunohistochemical staining for MIA, MMP-10, and DKK4 was found in 47 (31.1%), 68 (45.0%), and two (1.3%) of 151 GCs, respectively, and staining for both MIA and MMP-10 was correlated with poor prognosis in advanced GC (P=0.0001 and 0.0141, respectively). Moreover, enzyme-linked immunosorbent assay showed high levels of MMP-10 (65/69, 94.2%) in serum samples from patients with GC. Levels of MIA were raised in a small proportion of serum samples from patients with GC (4/69, 5.8%). In Boyden chamber invasion assays, MIA-transfected GC cells were up to three times more invasive than cells transfected with empty vector. Taken together, these results suggest that MMP-10 is a good marker for the detection of GC and that MIA and MMP-10 are prognostic factors for GC. As expression of MIA and MMP-10 is narrowly restricted in cancer, these two molecules may be good therapeutic targets for GC.