Pancreatic regenerating gene I and acinar cell differentiation: influence on cellular lineage

Serum REG Iα as a potential novel biomarker in cancer: An observational study

The regulation of the gene-regenerating family member 1 alpha (REG Iα) played important roles in cancer cell biology. However, the correlation between its gene product serum REG Iα and cancer has not been evaluated. In this observational study, 130 hospitalized patients from the department of internal medicine in Zhongda Hospital Southeast University were included and assigned to cancer or noncancer groups. History, clinical, and laboratory data were obtained. Serum REG Iα levels and alanine aminotransferase were found significantly higher in patients with cancer (P < .001 and P < .05 respectively). Logistic regression analysis indicated that REG Iα was an independent risk factor for cancer (P < .001). The area under the curve of REG Iα was 0.764 and the optimal cut-off point of REG Iα was 46.97 ng/mL. Besides, the cancer patients with metastasis had significantly higher serum REG Iα levels than those in nonmetastasis cancer group (P < .05). In conclusion, serum REG Iα was significantly elevated in patients with cancer, and it might be a potential biomarker in predicting cancer occurrence and development.

The role of a novel C-type lectin-like protein from planarian in innate immunity and regeneration

Planarian, a representative of platyhelminthes, has strong regeneration ability and less complicated innate immune system. However, planarian immune system remains poorly understood. In this paper, a novel C-type lectin-like protein, namely, DjCTL was identified and characterized in Dugesia japonica. DjCTL was mainly expressed in the pharyngeal and epidermis and up-regulated upon the induction of lipopolysaccharide (LPS), peptidoglycan (PGN), Gram-positive and Gram-negative bacteria indicating that DjCTL may be involved in the immune responses. Recombination DjCTL protein agglomerated rabbit red blood cells and interacted with LPS, PGN, mannose and galactose as well as both Gram-positive and Gram-negative bacteria, but it can only cause the agglutination of Gram-negative bacteria. Importantly, in the early periods of regeneration, DjCTL had a significantly high expression and was mainly expressed in early blastemas. RNA interference of DjCTL by dsRNA-DjCTL led to a slow wound healing during regeneration. These findings suggest that DjCTL participates in the innate immune response and plays an important role in early stages of regeneration.

Identification of a Three-Biomarker Panel in Urine for Early Detection of Pancreatic Adenocarcinoma

PURPOSE

Noninvasive biomarkers for early detection of pancreatic ductal adenocarcinoma (PDAC) are currently not available. Here, we aimed to identify a set of urine proteins able to distinguish patients with early-stage PDAC from healthy individuals.

EXPERIMENTAL DESIGN

Proteomes of 18 urine samples from healthy controls, chronic pancreatitis, and patients with PDAC (six/group) were assayed using GeLC/MS/MS analysis. The selected biomarkers were subsequently validated with ELISA assays using multiple logistic regression applied to a training dataset in a multicenter cohort comprising 488 urine samples.

RESULTS

LYVE-1, REG1A, and TFF1 were selected as candidate biomarkers. When comparing PDAC (n = 192) with healthy (n = 87) urine specimens, the resulting areas under the receiver-operating characteristic curves (AUC) of the panel were 0.89 [95% confidence interval (CI), 0.84-0.94] in the training (70% of the data) and 0.92 (95% CI, 0.86-0.98) in the validation (30% of the data) datasets. When comparing PDAC stage I-II (n = 71) with healthy urine specimens, the panel achieved AUCs of 0.90 (95% CI, 0.84-0.96) and 0.93 (95% CI, 0.84-1.00) in the training and validation datasets, respectively. In PDAC stage I-II and healthy samples with matching plasma CA19.9, the panel achieved a higher AUC of 0.97 (95% CI, 0.94-0.99) than CA19.9 (AUC = 0.88; 95% CI, 0.81-0.95, P = 0.005). Adding plasma CA19.9 to the panel increased the AUC from 0.97 (95% CI, 0.94-0.99) to 0.99 (95% CI, 0.97-1.00, P = 0.04), but did not improve the comparison of stage I-IIA PDAC (n = 17) with healthy urine.

CONCLUSIONS

We have established a novel, three-protein biomarker panel that is able to detect patients with early-stage pancreatic cancer in urine specimens.

Up-regulated Reg proteins induced by Interleukin-22 treatment ameliorate acute liver injury in rat model

BACKGROUND

The regenerating gene (Reg), encoding lectin-related protein, was originally isolated from a rat regenerating pancreatic islets. Interleukin-22 (IL-22), a recently identified cytokine, is produced by Th 17 cells and natural killer cells. Both of them have been shown to play an important role in controlling tissue repair. But, it is unclear whether the IL-22/Reg axis is involved in liver regeneration and the improvement of liver function in a rat model of acute liver injury.

AIMS

We investigated the expression levels of Reg proteins after IL-22 stimulation in a rat model of acute liver injury, and estimated the effects of Reg proteins ameliorating acute liver injury.

METHODS

Western blot was used to measure the expressions of Reg I, Reg III, Reg IV proteins after treatment with recombinant lentivirus IL-22. At the same time, the expression levels of TB, ALT, AST, endotoxin (ETM), superoxide dismutase (SOD), malondialdehyde (MDA) were detected by related reagents.

RESULTS

In a rat model of acute liver injury, the expression levels of Reg I, Reg III, Reg IV proteins were increased after treatment with IL-22 recombinant lentivirus compared with treatment with lentivirus-empty vector, especially, Reg IV protein expression. Meanwhile, treatment with IL-22 recombinant lentivirus reduced serum levels of TB, ALT, AST, ETM, and decreased MAD levels in rat liver tissues, but increased SOD levels in rat liver tissues.

CONCLUSION

IL-22 stimulation enhanced the expressions of Reg proteins in liver cell, especially, Reg IV protein, and ameliorated liver injury in a rat model of acute liver injury. Reg protein, especially Reg IV protein, might act as a biological mediator of immune cell-derived IL-22 in the recovering mechanism of liver injury.

Investigating the role of introns in the regulation of regenerating gene 1 expression

Gastrin is a hormone that physiologically regulates gastric acid secretion and contributes to the maintenance of gastric epithelial architecture by regulating the expression of genes such as regenerating gene 1 (Reg1). Reg1 is involved in gastric carcinogenesis as an antiapoptotic factor. The current study explores the molecular mechanism of gastrin-regulated Reg1 expression in human gastric cancer cells. In total, five intron fragments of the Reg1 gene were cloned by polymerase chain reaction and inserted into luciferase reporter vector pGL3 to construct intron-luciferase reporter vectors. After confirmation by Xho I/Hind III digestion and DNA sequencing, the five constructs were transfected into the SGC7901 gastric cancer cell line. The luciferase activity of the cells transfected with each of the five constructs was detected following incubation without or with gastrin. The five intron fragments of Reg1 were also randomly labeled with digoxin as a probe, and nuclear proteins of gastric cancer cells were extracted following treatment with or without gastrin. Southwestern blotting was subsequently performed to detect transcription factors that bind to the introns. The results indicated that the luciferase activity was significantly higher in cells transfected with recombinant vectors containing introns 2, 3, 4 or 5 than that in the cells transfected with an empty vector (P<0.05). However, no statistically significant difference in luciferase activity was identified between cells transfected with pGL3-intron 1 and those transfected with pGL3-Basic (P>0.05). Following incubation with gastrin, no significant difference was identified (P>0.05). The five introns of Reg1 can bind a number of transcription factors and gastrin may affect this interaction. Introns 2–5 of Reg1 potentially have transcriptional control over gene expression in gastric cancer cells. In conclusion, gastrin may regulate the expression of the Reg1 gene via the interaction of the introns by binding to the transcription factors.

Regenerating islet-derived 1α (Reg-1α) protein is new neuronal secreted factor that stimulates neurite outgrowth via exostosin Tumor-like 3 (EXTL3) receptor

Regenerating islet-derived 1α (Reg-1α)/lithostathine, a member of a family of secreted proteins containing a C-type lectin domain, is expressed in various organs and plays a role in proliferation, differentiation, inflammation, and carcinogenesis of cells of the digestive system. We previously reported that Reg-1α is overexpressed during the very early stages of Alzheimer disease, and Reg-1α deposits were detected in the brain of patients with Alzheimer disease. However, the physiological function of Reg-1α in neural cells remains unknown. Here, we show that Reg-1α is expressed in neuronal cell lines (PC12 and Neuro-2a) and in rat primary hippocampal neurons (E17.5). Reg-1α is mainly localized around the nucleus and at the membrane of cell bodies and neurites. Transient overexpression of Reg-1α or addition of recombinant Reg-1α significantly increases the number of cells with longer neurites by stimulating neurite outgrowth. These effects are abolished upon down-regulation of Reg-1α by siRNA and following inhibition of secreted Reg-1α by antibodies. Moreover, Reg-1α colocalizes with exostosin tumor-like 3 (EXTL3), its putative receptor, at the membrane of these cells. Overexpression of EXTL3 increases the effect of recombinant Reg-1α on neurite outgrowth, and Reg-1α is not effective when EXTL3 overexpression is down-regulated by shRNA. Our findings indicate that Reg-1α regulates neurite outgrowth and suggest that this effect is mediated by its receptor EXTL3.

Proteomic analysis of pancreatic juice for the identification of biomarkers of pancreatic cancer

INTRODUCTION

Protein profiles of endoscopically collected pancreatic juice from normal, chronic pancreatitis patients and pancreatic cancer patients were compared to identify diagnostic biomarkers of pancreatic cancer.

METHODS

Secretin was injected intravenously and pancreatic juice was collected via selective cannulation of the pancreatic duct during endoscopic retrograde cholangiopancreatography. Pancreatic juices consisting of three pooled samples for normal control, chronic pancreatitis, and pancreatic cancer patients were compared using two-dimensional gel electrophoresis, and the proteins were subsequently identified using MALDI-TOF-MS.

RESULTS

Thirty-five protein spots were up-regulated twofold in pancreatic cancer compared with the levels in the normal controls, and 85 protein spots were present in pancreatic cancer samples but not in normal controls. After excluding spots that were also expressed in chronic pancreatitis, 26 protein spots that were up-regulated or only expressed in pancreatic cancer samples were identified. Among the identified proteins, we confirmed the expressions of BIG2, PRDX6, and REG1α in pancreatic cancer tissue using immunohistochemistry. ELISA showed that the serum level of REG1α was significantly higher in patients with pancreatic cancer than it was in the normal controls (P = 0.023). With the best cut-off value, the sensitivity and specificity of REG1α to differentiate normal and pancreatic cancer were 82.6 and 81.8%, compared with 69.6 and 100% for CA19-9.

CONCLUSIONS

We have shown that pancreatic juice is a good source of pancreatic cancer tumor markers. Further studies are needed to determine the clinical implications of REG1α and other markers.

Expression of Reg family proteins in embryonic stem cells and its modulation by Wnt/beta-catenin signaling

Regenerating islet (Reg) proteins are involved in the proliferation and differentiation of diverse cell types. However, whether embryonic stem cells (ESCs) express Reg genes and their corresponding proteins remains unknown. In this study, we probed the expression of Reg family members by mouse ESCs (mESCs). Mouse Reg1 and Reg3gamma were detected in undifferentiated stem cells. Furthermore, we tested if gastrin--an inducer of Reg1 expression in committed cells--up-regulates the Reg1 gene in mESCs. Gastrin did not affect the expression of Reg1 either in self-renewing mESCs or under conditions permitting their differentiation. Moreover, overexpression of Reg genes found in various forms of cancer has been linked to dysregulated activation of the canonical Wnt/beta-catenin cascade. Given the important roles of Wnt signaling in stem cells, we investigated if activation of Wnt alters the expression of Reg genes in mESCs. Wnt activation led to an increase in Reg1 gene expression with a concomitant increase in the amount of secreted Reg1 protein. Finally, the expression pattern of genes indicative of differentiation was examined in mESCs that were either exposed to soluble Reg1 or overexpressed the Reg1 gene. This is the first account of expression of Reg family members by ESCs. Our results show that the canonical Wnt cascade affects Reg expression and warrants further studies into the potential roles of Reg proteins in stem cell physiology.

Pancreatic reg I binds MKP-1 and regulates cyclin D in pancreatic-derived cells

BACKGROUND

The pancreatic regenerating (reg I) gene and its protein product are derived from acinar cells and are mitogenic to beta- and ductal cells. We studied the mechanism of this mitogenic response.

MATERIALS AND METHODS

ARIP (rat ductal) and RIN 1046-38 (rat beta-) cell lines were exposed to exogenous reg I in culture or transfected with a reg I expression vector. Mitogenesis was assessed by MTS assay (CellTiter 96; Promega, Inc., Madison, WI), and cellular mRNA was subjected to gene microarray analysis to determine signal transduction pathways. Yeast two-hybrid technology was then used to determine intracellular binding of reg I protein.

RESULTS

Cells exposed to exogenous reg I showed a mitogenic response; cells transfected with reg I expression vector showed inhibited growth. Microarray analysis of the former showed induction of cyclin pathways and mitogen-activated protein kinase phosphatase (MKP-1); cyclins were inhibited in the latter. Northern analysis confirmed gene induction of cyclin D1 and MKP-1; JNK was phosphorylated prior to expression of both. Yeast two-hybrid analysis confirmed a protein-protein interaction with MKP-1; this was confirmed by immunoprecipitation.

CONCLUSIONS

Pancreatic-derived cells exposed to reg I grow by activation of signal transduction pathways involving the mitogen-activated protein kinase phosphatases and cyclins, with concomitant induction of MKP-1. However, high intracellular levels of reg I lead to decreased growth, likely via a binding to and inactivation of MKP-1. Inhibition of cell growth, and possible induction of apoptosis, may lead to differentiation of these cells to other cell types.