P8 expression is induced in acinar cells during chronic pancreatitis

The role of NUPR1 in response to stress and cancer development

Stress contributes to the development of many human diseases, including cancer. Based on the source of stress, it can be divided into external stress, such as environmental carcinogens, chemicals, and radiation, and internal stress, like endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Nuclear Protein 1 (NUPR1, p8 or Com-1) is a small, highly basic transcriptional regulator that participates in regulating a variety of cellular processes including DNA repair, ER stress, oxidative stress response, cell cycle, autophagy, apoptosis, ferroptosis and chromatin remodeling. A large number of studies have reported that NUPR1 expression can be stimulated rapidly in response to various stresses. Thus, NUPR1 is also known as a stress-response gene. Since the role of NUPR1 in breast cancer was identified in 1999, an increasing number of studies sought to reveal its function in cancer. High expression of NUPR1 has been identified in oral squamous cell carcinoma, breast cancer, lung cancer, multiple myeloma, liver cancer and renal cancer. In this review, we summarize current studies of NUPR1 in response to multiple external stressors and internal stressors, and its role in mediating stressors to cause different cell signaling responses. In addition, this review discusses the function of NUPR1 in carcinogenesis, tumorigenesis, metastasis, and cancer therapy. Thus, this review gives a comprehensive insight into the role of NUPR1 in mediating signals from stress to different cell responses, and this process plays a role in the development of cancer.

Targeting Fibrosis: The Bridge That Connects Pancreatitis and Pancreatic Cancer

Pancreatic fibrosis is caused by the excessive deposits of extracellular matrix (ECM) and collagen fibers during repeated necrosis to repair damaged pancreatic tissue. Pancreatic fibrosis is frequently present in chronic pancreatitis (CP) and pancreatic cancer (PC). Clinically, pancreatic fibrosis is a pathological feature of pancreatitis and pancreatic cancer. However, many new studies have found that pancreatic fibrosis is involved in the transformation from pancreatitis to pancreatic cancer. Thus, the role of fibrosis in the crosstalk between pancreatitis and pancreatic cancer is critical and still elusive; therefore, it deserves more attention. Here, we review the development of pancreatic fibrosis in inflammation and cancer, and we discuss the therapeutic strategies for alleviating pancreatic fibrosis. We further propose that cellular stress response might be a key driver that links fibrosis to cancer initiation and progression. Therefore, targeting stress proteins, such as nuclear protein 1 (NUPR1), could be an interesting strategy for pancreatic fibrosis and PC treatment.

Nuclear protein 1 promotes pancreatic cancer development and protects cells from stress by inhibiting apoptosis

Pancreatic ductal adenocarcinoma (PDAC) has the lowest survival rate of all cancers and shows remarkable resistance to cell stress. Nuclear protein 1 (Nupr1), which mediates stress response in the pancreas, is frequently upregulated in pancreatic cancer. Here, we report that Nupr1 plays an essential role in pancreatic tumorigenesis. In a mouse model of pancreatic cancer with constitutively expressed oncogenic Kras(G12D), we found that loss of Nupr1 protected from the development of pancreatic intraepithelial neoplasias (PanINs). Further, in cultured pancreatic cells, nutrient deprivation activated Nupr1 expression, which we found to be required for cell survival. We found that Nupr1 protected cells from stress-induced death by inhibiting apoptosis through a pathway dependent on transcription factor RelB and immediate early response 3 (IER3). NUPR1, RELB, and IER3 proteins were coexpressed in mouse PanINs from Kras(G12D)-expressing pancreas. Moreover, pancreas-specific deletion of Relb in a Kras(G12D) background resulted in delayed in PanIN development associated with a lack of IER3 expression. Thus, efficient PanIN formation was dependent on the expression of Nupr1 and Relb, with likely involvement of IER3. Finally, in patients with PDAC, expression of NUPR1, RELB, and IER3 was significantly correlated with a poor prognosis. Cumulatively, these results reveal a NUPR1/RELB/IER3 stress-related pathway that is required for oncogenic Kras(G12D)-dependent transformation of the pancreas.

Molecular mechanism of pancreatic β-cell adaptive proliferation: studies during pregnancy in rats and in vitro

There is a widespread interest in defining factors and mechanisms that stimulate proliferation of pancreatic islet β-cells. Pregnancy is a special period when the pancreatic islet displays a highly reproducible physiological proliferation. However, the molecular mechanism of β-cell proliferation during pregnancy is unclear. Here, we used cDNA expression array to explore gene expression profiles of islet at various stages of pregnancy in rats. Differentially expressed genes related to islet proliferation were screened by bioinformatics methods, and further verified by real-time PCR, RT-PCR, and Western blotting. Compared with control group, expressions of hundreds of genes were changed during pregnancy. The differentially expressed genes related to islet proliferation were mainly distributed in three groups: genes involved in transcription regulator activity, genes involved in apoptosis or tumor, and genes for Wnt signaling pathway. Among these genes, expressions of Nupr1, Atf3, Btg2, β-catenin, and c-Myc mRNA were up-regulated during pregnancy. A prominent expression of Nupr1 and Atf3 protein was observed in islets on day 10.5 of pregnancy, i.e., with earlier time phases than proliferation peak. Moreover, we found that prolactin (PRL) can increase the proliferation of β-cell in vitro, which is accompanied by up-regulation of Atf3 and Nupr1, indicating that they may play a crucial role in PRL-induced pancreatic β-cell growth. In conclusion, our results suggest that the transcription factor Nupr1, Atf3, and Wnt pathway may play an important role in adaptive proliferation of pancreatic islets during pregnancy in rats.

Multiple, temporal-specific roles for HNF6 in pancreatic endocrine and ductal differentiation

Within the developing pancreas Hepatic Nuclear Factor 6 (HNF6) directly activates the pro-endocrine transcription factor, Ngn3. HNF6 and Ngn3 are each essential for endocrine differentiation and HNF6 is also required for embryonic duct development. Most HNF6(-/-) animals die as neonates, making it difficult to study later aspects of HNF6 function. Here, we describe, using conditional gene inactivation, that HNF6 has specific functions at different developmental stages in different pancreatic lineages. Loss of HNF6 from Ngn3-expressing cells (HNF6(Delta endo)) resulted in fewer multipotent progenitor cells entering the endocrine lineage, but had no effect on beta cell terminal differentiation. Early, pancreas-wide HNF6 inactivation (HNF6(Delta panc)) resulted in endocrine and ductal defects similar to those described for HNF6 global inactivation. However, all HNF6(Delta panc) animals survived to adulthood. HNF6(Delta panc) pancreata displayed increased ductal cell proliferation and metaplasia, as well as characteristics of pancreatitis, including up-regulation of CTGF, MMP7, and p8/Nupr1. Pancreatitis was most likely caused by defects in ductal primary cilia. In addition, expression of Prox1, a known regulator of pancreas development, was decreased in HNF6(Delta panc) pancreata. These data confirm that HNF6 has both early and late functions in the developing pancreas and is essential for maintenance of Ngn3 expression and proper pancreatic duct morphology.

Loss of the protein NUPR1 (p8) leads to delayed LHB expression, delayed ovarian maturation, and testicular development of a sertoli-cell-only syndrome-like phenotype in mice

The high mobility group factor NUPR1, also known as p8 and com1, plays a role in temporal expression of the beta subunit of luteinizing hormone, LHB, during gonadotroph development. At Embryonic Day (e) 16.5, LHB is detectable in wild-type (Nupr1(+/+)) but not Nupr1 knockout (Nupr1(-/-)) mice. LHB is initiated by e17.5 in Nupr1(-/-) mice, and expression is fully recovered by Postnatal Day (p) 2. Factors indicative of pituitary maturation, GATA2, CGA, and TSH, are not differentially expressed in Nupr1(-/-) and Nupr1(+/+) embryos at e17.5. Therefore, the delay in LHB expression does not appear to result from delayed pituitary development. In addition, the role of NUPR1 in gonadotropin expression appears specific for LHB, as no difference in FSHB is observed in Nupr1(-/-) and Nupr1(+/+) embryos. The gonads are also impacted by the absence of NUPR1. Ovaries of female Nupr1(-/-) mice lack corpora lutea (CL) at 8 wk, an age at which CL are present in all Nupr1(+/+) littermates. Sexual maturity is recovered by 11 wk in Nupr1(-/-) mice. Conversely, the testes of Nupr1(-/-) males appear normal through 8 mo of age. By 10 mo, however, these mice develop a condition in which a significant number of seminiferous tubules lack germ cells, an abnormality reminiscent of human Sertoli-cell-only syndrome. NUPR1 is undetectable in Nupr1(+/+) gonadotrophs by p2 and remains absent in adulthood, but quantitative PCR analysis indicates Nupr1(+/+) adult ovaries and testes express Nupr1 mRNA. Therefore, the ovarian and testicular phenotypes may be due to the loss of NUPR1 directly at the gonads.

Glucose-dependent expansion of pancreatic beta-cells by the protein p8 in vitro and in vivo

p8 protein expression is known to be upregulated in the exocrine pancreas during acute pancreatitis. Own previous work revealed glucose-dependent p8 expression also in endocrine pancreatic beta-cells. Here we demonstrate that glucose-induced INS-1 beta-cell expansion is preceded by p8 protein expression. Moreover, isopropylthiogalactoside (IPTG)-induced p8 overexpression in INS-1 beta-cells (p8-INS-1) enhances cell proliferation and expansion in the presence of glucose only. Although beta-cell-related gene expression (PDX-1, proinsulin I, GLUT2, glucokinase, amylin) and function (insulin content and secretion) are slightly reduced during p8 overexpression, removal of IPTG reverses beta-cell function within 24 h to normal levels. In addition, insulin secretion of p8-INS-1 beta-cells in response to 0-25 mM glucose is not altered by preceding p8-induced beta-cell expansion. Adenovirally transduced p8 overexpression in primary human pancreatic islets increases proliferation, expansion, and cumulative insulin secretion in vitro. Transplantation of mock-transduced control islets under the kidney capsule of immunosuppressed streptozotocin-diabetic mice reduces blood glucose and increases human C-peptide serum concentrations to stable levels after 3 days. In contrast, transplantation of equal numbers of p8-transduced islets results in a continuous decrease of blood glucose and increase of human C-peptide beyond 3 days, indicating p8-induced expansion of transplanted human beta-cells in vivo. This is underlined by a doubling of insulin content in kidneys containing p8-transduced islet grafts explanted on day 9. These results establish p8 as a novel molecular mediator of glucose-induced pancreatic beta-cell expansion in vitro and in vivo and support the notion of existing beta-cell replication in the adult organism.

The murine p8 gene promoter is activated by activating transcription factor 4 (ATF4) in the gonadotrope-derived LbetaT2 cell line

The factor p8 is a high mobility group (HMG) A family member that is upregulated during the cellular stress response in numerous tissues. Because expression of this protein encourages cellular transformation, our goal is to characterize the mechanism by which the p8 gene is regulated. Using LbetaT2 cells as a model of a transformed cell in which p8 plays a role in tumor formation, we dissected the p8 promoter into its minimal functional units and found that activating transcription factor 4 (ATF4), a factor also upregulated during cellular stress responses, enhances p8 promoter activity in a dose-dependent manner. In addition, ATF4 binds in the highly conserved major activation domain of the p8 proximal promoter between -130 and -100 bp. Furthermore, we show that six of the nine base pairs that encompass the putative element are essential for ATF4 binding. These findings increase our knowledge of the mechanisms regulating the p8 gene in a genetically defined tumor model.

Chronic pancreatitis: evolving paradigms

Chronic pancreatitis (CP) is characterized by progressive fibrosis, pain and/or loss of exocrine and endocrine functions. With the identification and characterization of pancreatic stellate cells (PSCs), the pathogenesis of CP and pancreatic fibrosis is now better understood. Molecular mediators shown to regulate the pathogenesis include transforming growth factor-beta, platelet-derived growth factor, and proinflammatory cytokines such as interleukin (IL)-1, IL-6 and tumor necrosis factor-alpha. Besides these, the roles of cyclooxygenase (COX)-2 and apoptosis-related proteins have also been implicated in the pathogenesis. Furthermore, molecular pathways involving mitogen-activated protein kinases, phosphatidylinositol 3-kinase, Ras superfamily G proteins, serine threonine protein kinase Raf-1 and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) have been elucidated. Newer pathobiologic concepts concerning pain generation have also been put forward. Understanding the pathogenesis has led to the identification of novel molecular targets and the development of newer potential therapeutic agents. Those found to retard the progression of experimental CP and fibrosis in animal models include antioxidants, a Japanese herbal medicine called Saiko-keisi-to (TJ 10), the PPAR-gamma ligand troglitazone, the protease inhibitor Camostat mesilate, and Lovastatin.

p8 Upregulation sensitizes astrocytes to oxidative stress

Here we studied the mechanism of cell sensitization to oxidative stress by analyzing the gene expression profile of serum-deprived astrocytes. Exposure to serum-free medium (i) sensitized astrocytes to oxidative stress, (ii) reduced the expression of several genes involved in protection against oxidative stress, including heme oxygenase 1, and (iii) changed the expression of several genes involved in the control of cell survival, including the stress-regulated protein p8. Our results support that serum deprivation sensitizes astrocytes to oxidative stress via a p38 mitogen-activated protein kinase-dependent p8 upregulation that leads in turn to decreased heme oxygenase 1 expression.

Expression of vacuole membrane protein 1 (VMP1) in spontaneous chronic pancreatitis in the WBN/Kob rat

OBJECTIVES

VMP1 is a stress-induced gene that is overexpressed in acute pancreatitis. Its overexpression promotes the formation of intracellular vacuoles and cell death. We investigated the expression of VMP1 mRNA and its relation to apoptosis in spontaneous chronic pancreatitis in the WBN/Kob rat.

METHODS

Four-week-old male WBN/Kob rats were fed a special breeding diet, MB-3, for 20 weeks. Rats were killed every 4 weeks, and the pancreas was examined. VMP1 mRNA expression was determined by reverse transcriptase polymerase chain reaction with a semiquantitative analysis, direct sequencing, and in situ hybridization. Immunohistochemistry for proliferating cell nuclear antigen (PCNA) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) were used to detect cell proliferation and apoptosis, respectively.

RESULTS

Vacuolar formation was most prominent at 12 weeks, when chronic pancreatitis occurred. VMP1 mRNA was also strongly expressed at 12 weeks. In situ hybridization revealed VMP1 mRNA was expressed in acinar cells. Apoptosis was increased at 12 and 20 weeks, and PCNA expression was strongest at 16 weeks in the course of chronic pancreatitis.

CONCLUSIONS

VMP1 mRNA expression paralleled the formation of vacuoles and apoptosis in acinar cells in the course of chronic pancreatitis in WBN/Kob rats.