The human NUPR1/P8 gene is transcriptionally activated by transforming growth factor β via the SMAD signalling pathway

Suppression of NUPR1 in fibroblast-like synoviocytes reduces synovial fibrosis via the Smad3 pathway

BACKGROUND

Synovial fibrosis is a common complication of knee osteoarthritis (KOA), a pathological process characterized by myofibroblast activation and excessive extracellular matrix (ECM) deposition. Fibroblast-like synoviocytes (FLSs) are implicated in KOA pathogenesis, contributing to synovial fibrosis through diverse mechanisms. Nuclear protein 1 (NUPR1) is a recently identified transcription factor with crucial roles in various fibrotic diseases. However, its molecular determinants in KOA synovial fibrosis remain unknown. This study aims to investigate the role of NUPR1 in KOA synovial fibrosis through in vivo and in vitro experiments.

METHODS

We examined NUPR1 expression in the murine synovium and determined the impact of NUPR1 on synovial fibrosis by knockdown models in the destabilization of the medial meniscus (DMM)-induced KOA mouse model. TGF-β was employed to induce fibrotic response and myofibroblast activation in mouse FLSs, and the role and molecular mechanisms in synovial fibrosis were evaluated under conditions of NUPR1 downexpression. Additionally, the pharmacological effect of NUPR1 inhibitor in synovial fibrosis was assessed using a surgically induced mouse KOA model.

RESULTS

We found that NUPR1 expression increased in the murine synovium after DMM surgical operation. The adeno-associated virus (AAV)-NUPR1 shRNA promoted NUPR1 deficiency, attenuating synovial fibrosis, inhibiting synovial hyperplasia, and significantly reducing the expression of pro-fibrotic molecules. Moreover, the lentivirus-mediated NUPR1 deficiency alleviated synoviocyte proliferation and inhibited fibroblast to myofibroblast transition. It also decreased the expression of fibrosis markers α-SMA, COL1A1, CTGF, Vimentin and promoted the activation of the SMAD family member 3 (SMAD3) pathway. Importantly, trifluoperazine (TFP), a NUPR1 inhibitor, attenuated synovial fibrosis in DMM mice.

CONCLUSIONS

These findings indicate that NUPR1 is an antifibrotic modulator in KOA, and its effect on anti-synovial fibrosis is partially mediated by SMAD3 signaling. This study reveals a promising target for developing novel antifibrotic treatment.

Nupr1 deficiency downregulates HtrA1, enhances SMAD1 signaling, and suppresses age-related bone loss in male mice

Nuclear protein 1 (NUPR1) is a stress-induced protein activated by various stresses, such as inflammation and oxidative stress. We previously reported that Nupr1 deficiency increased bone volume by enhancing bone formation in 11-week-old mice. Analysis of differentially expressed genes between wild-type (WT) and Nupr1-knockout (Nupr1-KO) osteocytes revealed that high temperature requirement A 1 (HTRA1), a serine protease implicated in osteogenesis and transforming growth factor-β signaling was markedly downregulated in Nupr1-KO osteocytes. Nupr1 deficiency also markedly reduced HtrA1 expression, but enhanced SMAD1 signaling in in vitro-cultured primary osteoblasts. In contrast, Nupr1 overexpression enhanced HtrA1 expression in osteoblasts, suggesting that Nupr1 regulates HtrA1 expression, thereby suppressing osteoblastogenesis. Since HtrA1 is also involved in cellular senescence and age-related diseases, we analyzed aging-related bone loss in Nupr1-KO mice. Significant spine trabecular bone loss was noted in WT male and female mice during 6-19 months of age, whereas aging-related trabecular bone loss was attenuated, especially in Nupr1-KO male mice. Moreover, cellular senescence-related markers were upregulated in the osteocytes of 6-19-month-old WT male mice but markedly downregulated in the osteocytes of 19-month-old Nupr1-KO male mice. Oxidative stress-induced cellular senescence stimulated Nupr1 and HtrA1 expression in in vitro-cultured primary osteoblasts, and Nupr1 overexpression enhanced p16^ink4a expression in osteoblasts. Finally, NUPR1 expression in osteocytes isolated from the bones of patients with osteoarthritis was correlated with age. Collectively, these results indicate that Nupr1 regulates HtrA1-mediated osteoblast differentiation and senescence. Our findings unveil a novel Nupr1/HtrA1 axis, which may play pivotal roles in bone formation and age-related bone loss.

Ferroptosis, a Rising Force against Renal Fibrosis

Ferroptosis is a type of programmed cell death characterized by iron overload, oxidative stress, imbalance in lipid repair, and mitochondria-specific pathological manifestations. Growing number of molecular mechanisms and signaling pathways have been found to be involved in ferroptosis progression, including iron metabolism, amino acid metabolism, lipid metabolism, and energy metabolism. It is worth noting that ferroptosis is involved in the progression of fibrotic diseases such as liver cirrhosis, cardiomyopathy, and idiopathic pulmonary fibrosis, and inhibition of ferroptosis has acquired beneficial outcomes in rodent models, while studies on ferroptosis and renal fibrosis remains limited. Recent studies have revealed that targeting ferroptosis can effectively mitigate chronic kidney injury and renal fibrosis. Moreover, myofibroblasts suffer from ferroptosis during fiber and extracellular matrix deposition in the fibrotic cascade reaction and pharmacological modulation of ferroptosis shows great therapeutic effect on renal fibrosis. Here, we summarize the latest molecular mechanisms of ferroptosis from high-quality studies and review its therapeutic potential in renal fibrosis.

Upregulation of COPB2 Promotes Prostate Cancer Proliferation and Invasion Through the MAPK/TGF-β Signaling Pathway

There is increasing evidence that coatomer protein complex subunit beta 2 (COPB2) plays an important role in various cancer types. This study explored the role and the downstream mediators of COPB2 in prostate cancer (PCa). The expression of COPB2 was determined by the Cancer Genome Atlas database and enzyme-linked immunosorbent assay. COPB2 expression was upregulated in PCa tissues and correlated with Gleason score, biochemical recurrence, and poor prognosis. The functional roles of COPB2 in PCa were verified through a series of experiments. Knocking down COPB2 expression inhibited the growth and clonogenesis of PCa cells, promoted cell apoptosis, and inhibited the ability of scratch repair, invasion of PCa cells, and tumor growth in Nude mice. To analyze downstream signaling pathways, ingenuity pathway analysis, GSEA, and whole-genome expression spectrum GeneChip analysis were used. Western blot revealed that COPB2 expression promoted the proliferation and invasion of PCa cells by regulating the MAPK/TGF-β signaling pathway. The interacting protein (nuclear protein 1, NUPR1) was identified via Co-IP, real-time PCR, Western blot, and TCGA database in sampled tissues. The expressions of the interaction proteins NUPR1 and COPB2 were negatively regulated by each other. COPB2 could be a new biomarker for PCa diagnosis and monitoring and to provide a theoretical basis for identifying effective drug intervention targets through in-depth mechanistic studies.

Transcriptomic Profiling of Gene Expression Associated with Granulosa Cell Tumor Development in a Mouse Model

Ovarian granulosa cell tumors (GCTs) are rare sex cord-stromal tumors, accounting for ~5% ovarian tumors. The etiology of GCTs remains poorly defined. Genetically engineered mouse models are potentially valuable for understanding the pathogenesis of GCTs. Mice harboring constitutively active TGFβ signaling (TGFBR1-CA) develop ovarian GCTs that phenocopy several hormonal and molecular characteristics of human GCTs. To determine molecular alterations in the ovary upon TGFβ signaling activation, we performed transcriptomic profiling of gene expression associated with GCT development using ovaries from 1-month-old TGFBR1-CA mice and age-matched controls. RNA-sequencing and bioinformatics analysis coupled with the validation of select target genes revealed dysregulations of multiple cellular events and signaling molecules/pathways. The differentially expressed genes are enriched not only for known GCT-related pathways and tumorigenic events but also for signaling events potentially mediated by neuroactive ligand-receptor interaction, relaxin signaling, insulin signaling, and complements in TGFBR1-CA ovaries. Additionally, a comparative analysis of our data in mice with genes dysregulated in human GCTs or granulosa cells overexpressing a mutant FOXL2, the genetic hallmark of adult GCTs, identified some common genes altered in both conditions. In summary, this study has revealed the molecular signature of ovarian GCTs in a mouse model that harbors the constitutive activation of TGFBR1. The findings may be further exploited to understand the pathogenesis of a class of poorly defined ovarian tumors.

Bioinformatics analysis of key genes and potential mechanism in cadmium-induced breast cancer progression

Cadmium (Cd) may be associated with breast cancer progression, but the detailed molecular mechanism has not been fully elucidated. In this study, one public dataset (GSE136595) was used to identify differentially expressed genes (DEGs) in Cd-treated MCF-7 breast cancer cells. We determined a total of 2077 DEGs, and Ingenuity Pathway Analysis (IPA) software showed that 246 of them were related to tumor progression. Pathway analysis of these DEGs indicated that the HIF1α signaling and the epithelial-mesenchymal transition (EMT) pathway regulated by growth factors might be activated. Moreover, twist family bHLH transcription factor 1 (TWIST1), lysine demethylase 3A (KDM3A), Kruppel-like factor 4 (KLF4), nuclear protein 1 (NUPR1), neurogenin 3 (NEUROG3), and HNF1 homeobox B (HNF1B) might be the key transcription factors. And the result of protein-protein interaction (PPI) analysis showed that the hub genes in these 246 DEGs were tumor protein p53 (TP53), polo-like kinase 1 (PLK1), sirtuin 1 (SIRT1), protein tyrosine phosphatase non-receptor type 11 (PTPN11), caspase 8 (CASP8), cyclin-dependent kinase 6 (CDK6), calmodulin 3 (CALM3), KRAS proto-oncogene (KRAS), extra spindle pole bodies like 1 (ESPL1), and marker of proliferation Ki-67 (MKI67). Further analysis indicated that TWIST1, NUPR1, KRAS, and PTPN11 were related to the prognostic of breast cancer based on the Cancer Genome Atlas (TCGA) and they were validated to be upregulated in the Cd-treated MCF-7 cells. Our results suggested that the HIF1α signaling and the EMT pathway regulated by growth factors might be participant in the Cd-induced breast cancer progression and TWIST1, NUPR1, KRAS, and PTPN11 might be potential key genes.

Conditioned Media of Adipose-Derived Stem Cells Suppresses Sidestream Cigarette Smoke Extract Induced Cell Death and Epithelial-Mesenchymal Transition in Lung Epithelial Cells

The role of the epithelial-mesenchymal transition (EMT) in lung epithelial cells is increasingly being recognized as a key stage in the development of COPD, fibrosis, and lung cancers, which are all highly associated with cigarette smoking and with exposure to second-hand smoke. Using the exposure of human lung cancer epithelial A549 cells and non-cancerous Beas-2B cells to sidestream cigarette smoke extract (CSE) as a model, we studied the protective effects of adipose-derived stem cell-conditioned medium (ADSC-CM) against CSE-induced cell death and EMT. CSE dose-dependently induced cell death, decreased epithelial markers, and increased the expression of mesenchymal markers. Upstream regulator analysis of differentially expressed genes after CSE exposure revealed similar pathways as those observed in typical EMT induced by TGF-β1. CSE-induced cell death was clearly attenuated by ADSC-CM but not by other control media, such as a pass-through fraction of ADSC-CM or A549-CM. ADSC-CM effectively inhibited CSE-induced EMT and was able to reverse the gradual loss of epithelial marker expression associated with TGF-β1 treatment. CSE or TGF-β1 enhanced the speed of A549 migration by 2- to 3-fold, and ADSC-CM was effective in blocking the cell migration induced by either agent. Future work will build on the results of this in vitro study by defining the molecular mechanisms through which ADSC-CM protects lung epithelial cells from EMT induced by toxicants in second-hand smoke.

Nupr1 mediates renal fibrosis via activating fibroblast and promoting epithelial-mesenchymal transition

Renal interstitial fibrosis (RIF) is a pathological process that fibrotic components are excessively deposited in the renal interstitial space due to kidney injury, resulting in impaired renal function and chronic kidney disease. The molecular mechanisms controlling renal fibrosis are not fully understood. In this present study, we identified Nuclear protein 1 (Nupr1), a transcription factor also called p8, as a novel regulator promoting renal fibrosis. Unilateral ureteral obstruction (UUO) time-dependently induced Nupr1 mRNA and protein expression in mouse kidneys while causing renal damage and fibrosis. Nupr1 deficiency (Nupr1^-/- ) attenuated the renal tubule dilatation, tubular epithelial cell atrophy, and interstitial collagen accumulation caused by UUO. Consistently, Nupr1^-/- significantly decreased the expression of type I collagen, myofibroblast markers smooth muscle α-actin (α-SMA), fibroblast-specific protein 1 (FSP-1), and vimentin in mouse kidney that were upregulated by UUO. These results suggest that Nupr1 protein was essential for fibroblast activation and/or epithelial-mesenchymal transition (EMT) during renal fibrogenesis. Indeed, Nupr1 was indispensable for TGF-β-induced myofibroblast activation of kidney interstitial NRK-49F fibroblasts, multipotent mesenchymal C3H10T1/2 cells, and the EMT of kidney epithelial NRK-52E cells. It appears that Nupr1 mediated TGF-β-induced α-SMA expression and collagen synthesis by initiating Smad3 signaling pathway. Importantly, trifluoperazine (TFP), a Nupr1 inhibitor, alleviated UUO-induced renal fibrosis. Taken together, our results demonstrate that Nupr1 promotes renal fibrosis by activating myofibroblast transformation from both fibroblasts and tubular epithelial cells.

NUPR1: A Critical Regulator of the Antioxidant System

Simple Summary

Nuclear protein 1 (NUPR1) is activated in cellular stress and is expressed at high levels in cancer cells. Much evidence has been gathered supporting its critical role in regulating the antioxidant system. Our review aims to summarize the literature data on the impact of NUPR1 on the oxidative stress response via such a regulatory role and how its inhibition induces reactive oxygen species-mediated cell death, such as ferroptosis.

Abstract

Nuclear protein 1 (NUPR1) is a small intrinsically disordered protein (IDP) activated in response to various types of cellular stress, including endoplasmic reticulum (ER) stress and oxidative stress. Reactive oxygen species (ROS) are mainly produced during mitochondrial oxidative metabolism, and directly impact redox homeostasis and oxidative stress. Ferroptosis is a ROS-dependent programmed cell death driven by an iron-mediated redox reaction. Substantial evidence supports a maintenance role of the stress-inducible protein NUPR1 on cancer cell metabolism that confers chemotherapeutic resistance by upregulating mitochondrial function-associated genes and various antioxidant genes in cancer cells. NUPR1, identified as an antagonist of ferroptosis, plays an important role in redox reactions. This review summarizes the current knowledge on the mechanism behind the observed impact of NUPR1 on mitochondrial function, energy metabolism, iron metabolism, and the antioxidant system. The therapeutic potential of genetic or pharmacological inhibition of NUPR1 in cancer is also discussed. Understanding the role of NUPR1 in the antioxidant system and the mechanisms behind its regulation of ferroptosis may promote the development of more efficacious strategies for cancer therapy.

Cellular senescence as a response to multiwalled carbon nanotube (MWCNT) exposure in human mesothelial cells

Cellular senescence is a stable cell cycle arrest induced by diverse triggers, including replicative exhaustion, DNA damaging agents, oncogene activation, oxidative stress, and chromatin disruption. With important roles in aging and tumor suppression, cellular senescence has been implicated also in tumor promotion. Here we show that certain multiwalled carbon nanotubes (MWCNTs), as fiber-like nanomaterials, can trigger cellular senescence in primary human mesothelial cells. Using in vitro approaches, we found manifestation of several markers of cellular senescence, especially after exposure to a long and straight MWCNT. These included inhibition of cell division, senescence-associated heterochromatin foci, senescence-associated distension of satellites, LMNB1 depletion, γH2A.X nuclear panstaining, and enlarged cells exhibiting senescence-associated β-galactosidase activity. Furthermore, genome-wide transcriptome analysis revealed many differentially expressed genes, among which were genes encoding for a senescence-associated secretory phenotype. Our results clearly demonstrate the potential of long and straight MWCNTs to induce premature cellular senescence. This finding may find relevance in risk assessment of workplace safety, and in evaluating MWCNT's use in medicine such as drug carrier, due to exposure effects that might prompt onset of age-related diseases, or even carcinogenesis.

Targeting NUPR1 for Cancer Treatment: A Risky Endeavor

NUPR1 is a transcription factor that has attracted great attention because of its various roles in cancer. Several studies were carried out to determine its molecular targets and mechanism of action to develop novel therapies against cancer. Here, we shed light on the role of NUPR1 in different types of cancer. NUPR1 regulates a complex network of pathways that may be affected by its silencing, which can cause varying effects. Its role in some types of cancer has been reported but remains incompletely understood, whereas its roles in other types of cancers have not been reported yet. Therefore, targeting NUPR1 for cancer treatment remains challenging and risky.

Generation of an Fsp1 (fibroblast-specific protein 1)-Flpo transgenic mouse strain

Recombination systems represent a major breakthrough in the field of genetic model engineering. The Flp recombinases (Flp, Flpe, and Flpo) bind and cleave DNA Frt sites. We created a transgenic mouse strain ([Fsp1‐Flpo]) expressing the Flpo recombinase in fibroblasts. This strain was obtained by random insertion inside mouse zygotes after pronuclear injection. Flpo expression was placed under the control of the promoter of Fsp1 (fibroblast‐specific protein 1) gene, whose expression starts after gastrulation at Day 8.5 in cells of mesenchymal origin. We verified the correct expression and function of the Flpo enzyme by several ex vivo and in vivo approaches. The [Fsp1‐Flpo] strain represents a genuine tool to further target the recombination of transgenes with Frt sites specifically in cells of mesenchymal origin or with a fibroblastic phenotype.

Generation of a conditional Flpo/FRT mouse model expressing constitutively active TGFβ in fibroblasts

Transforming growth factor (TGFβ) is a secreted factor, which accumulates in tissues during many physio- and pathological processes such as embryonic development, wound healing, fibrosis and cancer. In order to analyze the effects of increased microenvironmental TGFβ concentration in vivo, we developed a conditional transgenic mouse model (Flpo/Frt system) expressing bioactive TGFβ in fibroblasts, a cell population present in the microenvironment of almost all tissues. To achieve this, we created the genetically-engineered [Fsp1-Flpo; ^FSFTGFβ^CA] mouse model. The Fsp1-Flpo allele consists in the Flpo recombinase under the control of the Fsp1 (fibroblast-specific promoter 1) promoter. The ^FSFTGFβ^CA allele consists in a transgene encoding a constitutively active mutant form of TGFβ (TGFβ^CA) under the control of a Frt-STOP-Frt (FSF) cassette. The ^FSFTGFβ^CA allele was created to generate this model, and functionally validated by in vitro, ex vivo and in vivo techniques. [Fsp1-Flpo; ^FSFTGFβ^CA] animals do not present any obvious phenotype despite the correct expression of TGFβ^CA transgene in fibroblasts. This [Fsp1-Flpo; ^FSFTGFβ^CA] model is highly pertinent for future studies on the effect of increased microenvironmental bioactive TGFβ concentrations in mice bearing Cre-dependent genetic alterations in other compartments (epithelial or immune compartments for instance). These dual recombinase system (DRS) approaches will enable scientists to study uncoupled spatiotemporal regulation of different genetic alterations within the same mouse, thus better replicating the complexity of human diseases.

Cardio-omentopexy Reduces Cardiac Fibrosis and Heart Failure After Experimental Pressure Overload

BACKGROUND

The pedicled greater omentum has been shown to offer benefit in ischemic heart disease for both animal models and human patients. The impact of cardio-omentopexy in a pressure overload model of left ventricular hypertrophy (LVH) is unknown.

METHODS

LVH was created in rats by banding the ascending aorta after right thoracotomy (n = 23). Sham surgery was performed in 12 additional rats. Six weeks after banding, surviving LVH rats were assigned to cardio-omentopexy by left thoracotomy (LVH+Om, n = 8) or sham left thoracotomy (LVH, n = 8). Sham rats also underwent left thoracotomy for cardio-omentopexy (Sham+Om, n = 6); the remaining rats underwent sham left thoracotomy (Sham, n = 6).

RESULTS

Echocardiography 10 weeks after cardio-omentopexy revealed LV end-systolic diameter, cardiomyocyte diamter, and myocardial fibrosis in the LVH group were significantly increased compared with the LVH+Om, Sham+Om, and Sham groups (p < 0.01). LV ejection fraction of the LVH group was lower than the LVH+Om group (p < 0.01). Gene expression analysis revealed significantly lower levels of sarcoendoplasmic reticulum calcium adenosine triphosphatase 2b in LVH rats than in the LVH+Om, Sham+Om, and Sham groups (p < 0.01). In contrast, collagen type 1 α 1 chain, lysyl oxidase-like protein 1, nuclear protein-1, and transforming growth factor- β1 in the LVH group were significantly higher than in the LVH+Om cohort (p < 0.01), consistent with a reduced fibrotic phenotype after omentopexy. Lectin staining showed myocardial capillary density of the LVH group was significantly lower than all other groups (p < 0.01).

CONCLUSIONS

Cardio-omentopexy reduced cardiac dilation, contractile dysfunction, cardiomyocyte hypertrophy, and myocardial fibrosis, while maintaining other molecular indicators of contractile function in this LVH model.

p8 deficiency leads to elevated pancreatic beta cell mass but does not contribute to insulin resistance in mice fed with high-fat diet

BACKGROUND

p8 was initially described as being overexpressed in acute pancreatitis and encoding a ubiquitous stress protein. Analysis of insulin sensitivity and glucose tolerance in p8-knockout and haplodeficient mice revealed counterintuitive results. Thus, we determined glycemic control of p8 in mice fed with standard (SD) and high-fat diet (HFD).

METHODS

p8-/- and wild type (p8+/+) mice were used for analysis of glucagon (immunohistochemistry), insulin levels (ELISA) and beta cell mass. Hyperinsulinemic- euglycemic glucose clamp technique, i.p. glucose tolerance test (ipGTT), i.p. insulin tolerance test (ipITT) and metabolic chamber analysis were performed in SD (4% fat) and HFD (55% fat) groups.

RESULTS

p8-/- mice showed no differences in glucagon or insulin content but higher insulin secretion from pancreatic islets upon glucose stimulation. p8 deficiency resulted in elevated beta cell mass but was not associated with increased insulin resistance in ipGTT or ipITT. Glucose clamp tests also revealed no evidence of association of p8 deficiency with insulin resistance. Metabolic chamber analysis showed equal energy expenditure in p8-/- mice and wild type animals.

CONCLUSION

p8 depletion may contribute to glucose metabolism via stress-induced insulin production and elevated beta cell mass. Nevertheless, p8 knockout showed no impact on insulin resistance in SD and HFD-fed mice.

Fluorofenidone Inhibits the Proliferation of Lung Adenocarcinoma Cells

Background: Lung carcinoma is the leading cause of malignant tumor related mortality in China in recent decades, and the development of new and effective therapies for patients with advanced lung carcinoma is needed. We recently found that fluorofenidone (FD), a newly developed pyridine compound, reduced the activation of Stat3 (Signal transducer and activator of transcription 3) in fibroblasts. Stat3 plays a crucial role in the development of lung cancer and may represent a new therapeutic target. In this study, we examined the effect of FD on human lung adenocarcinoma cells in vivo and in vitro.

Methods: The effect of FD on the growth of lung cancer cells was measured with a CCK-8 assay, colony formation assay and xenograft tumor model. A flow cytometry analysis was performed to study cell cycle arrest and apoptosis. Western blotting and immunohistochemistry were used to observe the expression of Stat3. Changes in the expression of RNA induced by FD were assessed using gene chip and real-time RT-PCR assays.

Results: In vitro, FD inhibited the growth of lung adenocarcinoma A549 and SPC-A1 cells in a dose-dependent manner. After treatment with FD, the A549 and SPC-A1 cells were arrested in the G1 phase, and apoptosis was induced. In vivo, this compound significantly inhibited the growth of tumors that were subcutaneously implanted in mice. Moreover, FD decreased Stat3 activity in lung cancer cells and xenograft tumor tissue, and microarray chip results showed that FD altered the gene expression profile of lung cancer cells. Specifically, NUPR1, which plays a significant role in cancer development, was down-regulated by FD in lung cancer cells.

Conclusion: Our study supports the clinical evaluation of FD as a potential lung adenocarcinoma therapy.

Estrogen receptor β, a regulator of androgen receptor signaling in the mouse ventral prostate

As estrogen receptor β^-/- (ERβ^-/-) mice age, the ventral prostate (VP) develops increased numbers of hyperplastic, fibroplastic lesions and inflammatory cells. To identify genes involved in these changes, we used RNA sequencing and immunohistochemistry to compare gene expression profiles in the VP of young (2-mo-old) and aging (18-mo-old) ERβ^-/- mice and their WT littermates. We also treated young and old WT mice with an ERβ-selective agonist and evaluated protein expression. The most significant findings were that ERβ down-regulates androgen receptor (AR) signaling and up-regulates the tumor suppressor phosphatase and tensin homolog (PTEN). ERβ agonist increased expression of the AR corepressor dachshund family (DACH1/2), T-cadherin, stromal caveolin-1, and nuclear PTEN and decreased expression of RAR-related orphan receptor c, Bcl2, inducible nitric oxide synthase, and IL-6. In the ERβ^-/- mouse VP, RNA sequencing revealed that the following genes were up-regulated more than fivefold: Bcl2, clusterin, the cytokines CXCL16 and -17, and a marker of basal/intermediate cells (prostate stem cell antigen) and cytokeratins 4, 5, and 17. The most down-regulated genes were the following: the antioxidant gene glutathione peroxidase 3; protease inhibitors WAP four-disulfide core domain 3 (WFDC3); the tumor-suppressive genes T-cadherin and caveolin-1; the regulator of transforming growth factor β signaling SMAD7; and the PTEN ubiquitin ligase NEDD4. The role of ERβ in opposing AR signaling, proliferation, and inflammation suggests that ERβ-selective agonists may be used to prevent progression of prostate cancer, prevent fibrosis and development of benign prostatic hyperplasia, and treat prostatitis.

Functional Characterization of Nupr1L, A Novel p53-Regulated Isoform of the High-Mobility Group (HMG)-Related Protumoral Protein Nupr1

We have previously demonstrated a crucial role of nuclear protein 1 (NUPR1) in tumor development and progression. In this work, we report the functional characterization of a novel Nupr1-like isoform (NUPR1L) and its functional interaction with the protumoral factor NUPR1. Through the use of primary sequence analysis, threading, and homology-based molecular modeling, as well as expression and immunolocalization, studies reveal that NUPR1L displays properties, which are similar to member of the HMG-like family of chromatin regulators, including its ability to translocate to the cell nucleus and bind to DNA. Analysis of the NUPR1L promoter showed the presence of two p53-response elements at positions -37 and -7, respectively. Experiments using reporter assays combined with site-directed mutagenesis and using cells with controllable p53 expression demonstrate that both of these sequences are responsible for the regulation of NUPR1L expression by p53. Congruently, NUPR1L gene expression is activated in response to DNA damage induced by oxaliplatin treatment or cell cycle arrest induced by serum starvation, two well-validated methods to achieve p53 activation. Interestingly, expression of NUPR1L downregulates the expression of NUPR1, its closely related protumoral isoform, by a mechanism that involves the inhibition of its promoter activity. At the cellular level, overexpression of NUPR1L induces G1 cell cycle arrest and a decrease in their cell viability, an effect that is mediated, at least in part, by downregulating NUPR1 expression. Combined, these experiments constitute the first functional characterization of NUPR1L as a new p53-induced gene, which negatively regulates the protumoral factor NUPR1.

Hepatitis B virus X promotes hepatocellular carcinoma development via nuclear protein 1 pathway

Hepatocellular carcinoma (HCC) is one of the most common malignancies and chronic hepatitis B virus (HBV) infection is a major risk factor for HCC. Hepatitis B virus X (HBx) protein relates to trigger oncogenesis. HBx has oncogenic properties with a hyperproliferative response to HCC. Nuclear protein 1 (NUPR1) is a stress-response protein, frequently upregulated in several cancers. Recent data revealed that NUPR1 is involved in tumor progression, but its function in HCC is not revealed yet. Here we report HBx can induce NUPR1 in patients, mice, and HCC cell lines. In an HBx transgenic mouse model, we found that HBx overexpression upregulates NUPR1 expression consistently with tumor progression. Further, in cultured HBV positive cells, HBx knockdown induces downregulation of NUPR1. Smad4 is a representative transcription factor, regulated by HBx, and we showed that HBx upregulates NUPR1 by Smad4 dependent way. We found that NUPR1 can inhibit cell death and induce vasculogenic mimicry in HCC cell lines. Moreover, NUPR1 silencing in HepG2-HBx showed reduced cell motility. These results suggest that HBx can modulate NUPR1 expression through the Smad4 pathway and NUPR1 has a role in hepatocellular carcinoma progression.

Disturbance of gene expression in primary human hepatocytes by hepatotoxic pyrrolizidine alkaloids: A whole genome transcriptome analysis

1,2-unsaturated pyrrolizidine alkaloids (PA) are plant metabolites predominantly occurring in the plant families Asteraceae and Boraginaceae. Acute and chronic PA poisoning causes severe hepatotoxicity. So far, the molecular mechanisms of PA toxicity are not well understood. To analyze its mode of action, primary human hepatocytes were exposed to a non-cytotoxic dose of 100 μM of four structurally different PA: echimidine, heliotrine, senecionine, senkirkine. Changes in mRNA expression were analyzed by a whole genome microarray. Employing cut-off values with a |fold change| of 2 and a q-value of 0.01, data analysis revealed numerous changes in gene expression. In total, 4556, 1806, 3406 and 8623 genes were regulated by echimidine, heliotrine, senecione and senkirkine, respectively. 1304 genes were identified as commonly regulated. PA affected pathways related to cell cycle regulation, cell death and cancer development. The transcription factors TP53, MYC, NFκB and NUPR1 were predicted to be activated upon PA treatment. Furthermore, gene expression data showed a considerable interference with lipid metabolism and bile acid flow. The associated transcription factors FXR, LXR, SREBF1/2, and PPARα/γ/δ were predicted to be inhibited. In conclusion, though structurally different, all four PA significantly regulated a great number of genes in common. This proposes similar molecular mechanisms, although the extent seems to differ between the analyzed PA as reflected by the potential hepatotoxicity and individual PA structure.

Proteolytic control of TGF-β co-receptor activity by BMP-1/tolloid-like proteases revealed by quantitative iTRAQ proteomics

The metalloproteinase BMP-1 (bone morphogenetic protein-1) plays a major role in the control of extracellular matrix (ECM) assembly and growth factor activation. Most of the growth factors activated by BMP-1 are members of the TGF-β superfamily known to regulate multiple biological processes including embryonic development, wound healing, inflammation and tumor progression. In this study, we used an iTRAQ (isobaric tags for relative and absolute quantification)-based quantitative proteomic approach to reveal the release of proteolytic fragments from the cell surface or the ECM by BMP-1. Thirty-eight extracellular proteins were found in significantly higher or lower amounts in the conditioned medium of HT1080 cells overexpressing BMP-1 and thus, could be considered as candidate substrates. Strikingly, three of these new candidates (betaglycan, CD109 and neuropilin-1) were TGF-β co-receptors, also acting as antagonists when released from the cell surface, and were chosen for further substrate validation. Betaglycan and CD109 proved to be directly cleaved by BMP-1 and the corresponding cleavage sites were extensively characterized using a new mass spectrometry approach. Furthermore, we could show that the ability of betaglycan and CD109 to interact with TGF-β was altered after cleavage by BMP-1, leading to increased and prolonged SMAD2 phosphorylation in BMP-1-overexpressing cells. Betaglycan processing was also observed in primary corneal keratocytes, indicating a general and novel mechanism by which BMP-1 directly affects signaling by controlling TGF-β co-receptor activity. The proteomic data have been submitted to ProteomeXchange with the identifier PXD000786 and doi: 10.6019/PXD000786 .

p8 Deficiency causes siderosis in spleens and lymphocyte apoptosis in acute pancreatitis

OBJECTIVES

The gene p8 was initially described in pancreatic tissue during acute experimental pancreatitis, a disease that is characterized by a systemic immune response. Although early reports suggested that p8 affects leukocyte migration during acute pancreatitis (AP), no studies revealing its immune-modulatory effects have been performed.

METHODS

We investigated the composition of the cellular immune system in naive p8 knockout (p8(−/−)) mice and compared with matched wild-type mice during pancreatitis.

RESULTS

In young mice, there were no relevant differences in the composition of peripheral and splenic CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD11b(+)Gr-1(-), and Gr-1 cells. In mature p8(−/−) mice, increased splenic CD4CD25FoxP3 cells, spleen siderosis, and increased marginal zones in the splenic white pulp were found. During AP, peripheral and splenic CD3(+) and CD3CD4 declined stronger in the p8(−/−) mice. The spleen of the p8(−/−) mice showed severe hypoplasia of the white pulp and mild hyperplasia of the red pulp. This was associated with a significantly increased rate of apoptosis.

CONCLUSIONS

We conclude that p8 has no impact on the cellular composition of the adaptive and innate immune systems in noninflammatory conditions. However, it may limit apoptosis and maintain homeostasis of the immune reaction during AP.

Expression of p8 in Human Oral Squamous Cell Carcinoma

The present study investigated the expression of p8, a transcription factor upregulated in some human cancers, in oral squamous cell carcinomas (OSCCs). Immunohistochemical analysis of p8 expression was carried out on 20 archived surgical specimens of human OSCCs, and expression correlated with clinical outcome parameters in a retrospective study. Expression of p8 in a number of OSCC cell lines also was investigated by western blot and RT-PCR analyses. p8 was expressed in 80 % (16/20) of the samples with levels of expression exhibiting a significant difference (χ(2) = 8.352, df = 3, p = 0.039) by patient age. Furthermore, greater levels of p8 immunoreactivity was significantly associated with advanced tumor grade (p = 0.008). p8 also was upregulated in OSCC cell lines. p8 is expressed in a significant proportion of OSCCs, and in human OSCC cell lines, suggesting a potential value of p8 as a diagnostic and/prognostic tool for oral cancers.

Tenascin-X promotes epithelial-to-mesenchymal transition by activating latent TGF-β

Transforming growth factor β (TGF-β) isoforms are secreted as inactive complexes formed through noncovalent interactions between the bioactive TGF-β entity and its N-terminal latency-associated peptide prodomain. Extracellular activation of the latent TGF-β complex is a crucial step in the regulation of TGF-β function for tissue homeostasis. We show that the fibrinogen-like (FBG) domain of the matrix glycoprotein tenascin-X (TNX) interacts physically with the small latent TGF-β complex in vitro and in vivo, thus regulating the bioavailability of mature TGF-β to cells by activating the latent cytokine into an active molecule. Activation by the FBG domain most likely occurs through a conformational change in the latent complex and involves a novel cell adhesion-dependent mechanism. We identify α11β1 integrin as a cell surface receptor for TNX and show that this integrin is crucial to elicit FBG-mediated activation of latent TGF-β and subsequent epithelial-to-mesenchymal transition in mammary epithelial cells.

Genetic inactivation of Nupr1 acts as a dominant suppressor event in a two-hit model of pancreatic carcinogenesis

BACKGROUND

Nuclear protein 1 (Nupr1) is a major factor in the cell stress response required for Kras(G12D)-driven formation of pancreatic intraepithelial neoplastic lesions (PanINs). We evaluated the relevance of Nupr1 in the development of pancreatic cancer.

METHODS

We investigated the role of Nupr1 in pancreatic ductal adenocarcinoma (PDAC) progression beyond PanINs in Pdx1-cre;LSL-Kras(G12D);Ink4a/Arf(fl/fl)(KIC) mice.

RESULTS

Even in the context of the second tumorigenic hit of Ink4a/Arf deletion, Nupr1 deficiency led to suppression of malignant transformation involving caspase 3 activation in premalignant cells of KIC pancreas. Only half of Nupr1-deficient;KIC mice achieved PDAC development, and incident cases survived longer than Nupr1(wt);KIC mice. This was associated with the development of well-differentiated PDACs in Nupr1-deficient;KIC mice, which displayed enrichment of genes characteristic of the recently identified human classical PDAC subtype. Nupr1-deficient;KIC PDACs also shared with human classical PDACs the overexpression of the Kras-activation gene signature. In contrast, Nupr1(wt);KIC mice developed invasive PDACs with enriched gene signature of human quasi-mesenchymal (QM) PDACs. Cells derived from Nupr1-deficient;KIC PDACs growth in an anchorage-independent manner in vitro had higher aldehyde dehydrogenase activity and overexpressed nanog, Oct-4 and Sox2 transcripts compared with Nupr1(wt);KIC cells. Moreover, Nupr1-deficient and Nurpr1(wt);KIC cells differed in their sensitivity to the nucleoside analogues Ly101-4b and WJQ63. Together, these findings show the pivotal role of Nupr1 in both the initiation and late stages of PDAC in vivo, with a potential impact on PDAC cell stemness.

CONCLUSIONS

According to Nupr1 status, KIC mice develop tumours that phenocopy human classical or QM-PDAC, respectively, and present differential drug sensitivity, thus becoming attractive models for preclinical drug trials.

Nupr1 deletion protects against glucose intolerance by increasing beta cell mass

AIMS/HYPOTHESIS

The stress-activated nuclear protein transcription regulator 1 (NUPR1) is induced in response to glucose and TNF-α, both of which are elevated in type 2 diabetes, and Nupr1 has been implicated in cell proliferation and apoptosis cascades. We used Nupr1(-/-) mice to study the role of Nupr1 in glucose homeostasis under normal conditions and following maintenance on a high-fat diet (HFD).

METHODS

Glucose homeostasis in vivo was determined by measuring glucose tolerance, insulin sensitivity and insulin secretion. Islet number, morphology and beta cell area were assessed by immunofluorescence and morphometric analysis, and islet cell proliferation was quantified by analysis of BrdU incorporation. Islet gene expression was measured by gene arrays and quantitative RT-PCR, and gene promoter activities were monitored by measuring luciferase activity.

RESULTS

Nupr1(-/-) mice had increased beta cell mass as a consequence of enhanced islet cell proliferation. Nupr1-dependent suppression of beta cell Ccna2 and Tcf19 promoter activities was identified as a mechanism through which Nupr1 may regulate beta cell cycle progression. Nupr1(-/-) mice maintained on a normal diet were mildly insulin resistant, but were normoglycaemic with normal glucose tolerance because of compensatory increases in basal and glucose-induced insulin secretion. Nupr1 deletion was protective against HFD-induced obesity, insulin resistance and glucose intolerance.

CONCLUSIONS/INTERPRETATION

Inhibition of NUPR1 expression or activity has the potential to protect against the metabolic defects associated with obesity and type 2 diabetes.