The N-myc downstream regulated gene (NDRG) family: diverse functions, multiple applications

Mitochondrial ferritin upregulation by deferiprone reduced neuronal ferroptosis and improved neurological deficits via NDRG1/Yap pathway in a neonatal rat model of germinal matrix hemorrhage

Ferroptosis contributes to brain injury after germinal matrix hemorrhage (GMH). Mitochondrial ferritin (FTMT), a novel mitochondrial outer membrane protein, reduces oxidative stress in neurodegenerative diseases. In vitro, Deferiprone has been shown to upregulate FTMT. However, the effects of FTMT upregulation by Deferiprone on neuronal ferroptosis after GMH and its underlying mechanism has not been investigated. In our study, 389 Sprague-Dawley rat pups of postnatal day 7 were used to establish a collagenase-induced GMH model and an iron-overload model of intracerebral FeCl2 injection. The brain expressions of FTMT, N-myc downstream-regulated gene-1 (NDGR1), Yes-associated protein (YAP), ferroptosis-related molecules including transferrin receptor (TFR) and acyl-CoA synthase long-chain family member 4 (ACSL4) were increased after GMH. FTMT agonist Deferiprone improved neurological deficits and hydrocephalus after GMH. Deferiprone or Adenovirus-FTMT enhanced YAP phosphorylation at the Ser127 site and attenuated ferroptosis, which was reversed by NDRG1 CRISPR Knockout. Iron overload induced neuronal ferroptosis and neurological deficits, which were improved by YAP CRISPR Knockout. Collectively, FTMT upregulation by Deferiprone reduced neuronal ferroptosis and neurological deficits via the NDRG1/YAP signaling pathway after GMH. Deferiprone may serve as a potential non-invasive treatment for GMH patients.

Lactate and lactylation in cardiovascular diseases: current progress and future perspectives

Cardiovascular diseases (CVDs) are often linked to structural and functional impairments, such as heart defects and circulatory dysfunction, leading to compromised peripheral perfusion and heightened morbidity risks. Metabolic remodeling, particularly in the context of cardiac fibrosis and inflammation, is increasingly recognized as a pivotal factor in the pathogenesis of CVDs. Metabolic syndromes further predispose individuals to these conditions, underscoring the need to elucidate the metabolic underpinnings of CVDs. Lactate, a byproduct of glycolysis, is now recognized as a key molecule that connects cellular metabolism with the regulation of cellular activity. The transport of lactate between different cells is essential for metabolic homeostasis and signal transduction. Disruptions to lactate dynamics are implicated in various CVDs. Furthermore, lactylation, a novel post-translational modification, has been identified in cardiac cells, where it influences protein function and gene expression, thereby playing a significant role in CVD pathogenesis. In this review, we summarized recent advancements in understanding the role of lactate and lactylation in CVDs, offering fresh insights that could guide future research directions and therapeutic interventions. The potential of lactate metabolism and lactylation as innovative therapeutic targets for CVD is a promising avenue for exploration.

Elevated expression of N-myc downstream regulated gene 1 protein in glioblastomas reflects tumor angiogenesis and poor patient prognosis

N-myc downstream regulated gene 1 (NDRG1) is a member of the NDRG family, of which four members (NDRG1, NDRG2, NDRG3, and NDRG4) have been identified. NDRG1 is repressed by c-MYC and N-MYC proto-oncogenes. NDRG1 is translated into a 43 kDa protein that is associated with the regulation of cellular stress responses, proliferation, and differentiation. In this study, we aimed to clarify the relationship between progression of glioblastoma (GB) IDH-wildtype and NDRG1 expression in tumor cells. We assessed the expression of NDRG1 in 41 GBs using immunostaining and evaluated its prognostic significance. NDRG1 expression by GBs was evaluated using Histoscore, which showed high and low scores in 23 and 18 cases, respectively. NDRG1-positive cells were strongly expressed in Ki-67 labeled proliferating tumor cells and CD105 positive proliferating microvessels around the area of palisading necrosis. Statistical analyses showed lower survival rates in the high-score group than the low-score group (P < 0.01). This study indicated that overexpression of NDRG1 by GB reflects tumor angiogenesis and poor patient prognosis.

Novel Diagnostic Biomarkers Related to Necroptosis and Immune Infiltration in Coronary Heart Disease

Purpose

Necroptosis, a monitored form of inflammatory cell death, contributes to coronary heart disease (CHD) progression. This study examined the potential of using necroptosis genes as diagnostic markers for CHD and sought to elucidate the underlying roles.

Methods

Through bioinformatic analysis of GSE20680 and GSE20681, we first identified the differentially expressed genes (DEGs) related to necroptosis in CHD. Hub genes were identified using least absolute shrinkage and selection operator (LASSO) regression and random forest analysis after studying immune infiltration and transcription factor-miRNA interaction networks according to the DEGs. Quantitative polymerase chain reaction and immunohistochemistry were used to further investigate hub gene expression in vivo, for which a diagnostic model was constructed and the predictive efficacy was validated. Finally, the CHD group was categorized into high- and low-score groups in accordance with the single-sample gene set enrichment analysis (ssGSEA) score of the necroptosis genes. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, GSEA, and further immune infiltration analyses were performed on the two groups to explore the possible roles of hub genes.

Results

Based on the results of the LASSO regression and random forest analyses, four genes were used to construct a diagnostic model to establish a nomogram. Additionally, an extensive analysis of all seventeen necroptosis genes revealed notable distinctions in expression between high-risk and low-risk groups. Evaluation of immune infiltration revealed that neutrophils, monocytes, B cells, and activated dendritic cells were highly distributed in the peripheral blood of patients with CHD. Specifically, the high CHD score group exhibited greater neutrophil and monocyte infiltration. Conversely, the high-score group showed lower infiltration of M0 and M2 macrophages, CD8+ T, plasma, and resting mast cells.

Conclusion

TLR3, MLKL, HMGB1, and NDRG2 may be prospective biomarkers for CHD diagnosis. These findings offer plausible explanations for the role of necroptosis in CHD progression through immune infiltration and inflammatory response.

Identification of proteins related to SIS3 by iTRAQ and PRM-based comparative proteomic analysis in cisplatin-induced acute kidney injury

Background

Cisplatin is a commonly used nephrotoxic drug and can cause acute kidney injury (AKI). In the present study, isobaric tags for relative and absolute quantification (iTRAQ) and parallel reaction monitoring (PRM)-based comparative proteomics were used to analyze differentially expressed proteins (DEPs) to determine the key molecular mechanism in mice with cisplatin-induced AKI in the presence or absence of SIS3, a specific p-smad3 inhibitor, intervention.

Methods

The cisplatin-induced AKI mouse model was established and treated with SIS3. We used iTRAQ to search for DEPs, PRM to verify key DEPs and combined Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for bioinformatics analysis. We then assessed lipid deposition, malondialdehyde (MDA) and reactive oxygen species (ROS) and detected the expression of SREBF1, SCD1, CPT1A, PPARα and NDRG1 in vitro.

Results

Proteomic analysis showed that the identified DEPs were mainly enriched in energy metabolism pathways, especially in lipid metabolism. When SIS3 was applied to inhibit the phosphorylation of Smad3, the expression of NDRG1 and fatty acid oxidation key proteins CPT1A and PPARα increased, the expression of lipid synthesis related proteins SREBF1 and SCD1 decreased and the production of lipid droplets, MDA and ROS decreased.

Conclusion

SIS3 alleviates oxidative stress, reduces lipid accumulation and promotes fatty acid oxidation through NDRG1 in cisplatin-induced AKI. Our study provides a new candidate protein for elucidating the molecular mechanisms of fatty acid metabolism disorders in cisplatin-induced acute kidney injury.

Research progress and applications of epigenetic biomarkers in cancer

Epigenetic changes are heritable changes in gene expression without changes in the nucleotide sequence of genes. Epigenetic changes play an important role in the development of cancer and in the process of malignancy metastasis. Previous studies have shown that abnormal epigenetic changes can be used as biomarkers for disease status and disease prediction. The reversibility and controllability of epigenetic modification changes also provide new strategies for early disease prevention and treatment. In addition, corresponding drug development has also reached the clinical stage. In this paper, we will discuss the recent progress and application status of tumor epigenetic biomarkers from three perspectives: DNA methylation, non-coding RNA, and histone modification, in order to provide new opportunities for additional tumor research and applications.

Regulatory role of N-myc downregulated genes in amelogenesis in rats

Cytodifferentiation of odontogenic cells, a late stage event in odontogenesis is based on gene regulation. However, studies on the identification of the involved genes are scarce. The present study aimed to search for molecules for the cytodifferentiation of ameloblastic cells in rats. Differential display-PCR revealed a differentially expressed gene between cap/early bell stage and hard tissue formation stage in molars. This gene was identified as N-myc Downregulated Gene 1 (Ndrg1), which is the first report in tooth development. Real time PCR and western blotting confirmed that the mRNA level of Ndrg1 was higher during enamel formation than the cap stage. Ndrg1 expression was upregulated in the early bell, crown, and root stages in a time-dependent manner. These patterns of expression were similar in Ndrg2, but Ndrg3 and Ndrg4 levels did not change during the developmental stages. Immunofluorescence revealed that strong immunoreactivity against Ndrg1 were detected in differentiated ameloblasts only, not inner enamel epithelium, odontoblasts and ameloblastic cells in defected enamel regions. Alkaline phosphatase and alizarin red s stains along with real time PCR, revealed that Ndrg1 and Ndrg2 were involved in cytodifferentiation and enamel matrix mineralization by selectively regulating amelogenin and ameloblastin genes in SF2 ameloblastic cells. These results suggest that Ndrg may play a crucial functional role in the cytodifferentiation of ameloblasts for amelogenesis.

NDRG2 acts as a negative regulator of the progression of small-cell lung cancer through the modulation of the PTEN-AKT-mTOR signalling cascade

N-myc downstream-regulated gene 2 (NDRG2) has been recognised as a negative regulator of the progression of numerous tumours, yet its specific role in small-cell lung carcinoma (SCLC) is not fully understood. The purpose of the current study was to investigate the biological role and mechanism of NDRG2 in SCLC. Initial investigation using the Gene Expression Omnibus (GEO) dataset revealed marked downregulation of NDRG2 transcripts in SCLC. The decreased abundance of NDRG2 in SCLC was verified by examining clinical specimens. Increasing NDRG2 expression in SCLC cell lines caused significant changes in cell proliferation, cell cycle progression, colony formation, and chemosensitivity. NDRG2 overexpression decreased the levels of phosphorylated PTEN, AKT and mTOR. In PTEN-depleted SCLC cells, the upregulation of NDRG2 did not result in any noticeable impact on AKT or mTOR activation. Additionally, the reactivation of AKT reversed the antitumour effects of NDRG2 in SCLC cells. Notably, increasing NDRG2 expression retarded the growth of SCLC cell-derived xenografts in vivo. In conclusion, NDRG2 serves as an inhibitor of SCLC, and its cancer-inhibiting effects are achieved through the suppression of AKT/mTOR via the activation of PTEN. This work suggests that NDRG2 is a potential druggable target for SCLC treatment.

NDRGs in Breast Cancer: A Review and In Silico Analysis

The N-myc downstream regulated gene family (NDRGs) includes four members: NDRG1, NDRG2, NDRG3, and NDRG4. These members exhibit 53-65% amino acid identity. The role of NDRGs in tumor growth and metastasis appears to be tumor- and context-dependent. While many studies have reported that these family members have tumor suppressive roles, recent studies have demonstrated that NDRGs, particularly NDRG1 and NDRG2, function as oncogenes, promoting tumor growth and metastasis. Additionally, NDRGs are involved in regulating different signaling pathways and exhibit diverse cellular functions in breast cancers. In this review, we comprehensively outline the oncogenic and tumor suppressor roles of the NDRG family members in breast cancer, examining evidence from in vitro and in vivo breast cancer models as well as tumor tissues from breast cancer patients. We also present analyses of publicly available genomic and transcriptomic data from multiple independent cohorts of breast cancer patients.

Clinical role of NDRG2-based methylation status on survival pattern of glioblastoma

OBJECTIVES

Gliobalstoma is the most common primary brain tumor in adults with an extensive genetic and transcriptional heterogeneity, still identification of the role of DNA methylation, as one of epigenetic alterations, is emerged. Authors aimed to study the clinical role of N-myc downstream-regulated gene 2 (NDRG2) -based methylation among GBM patients versus benign neurological diseases (BND), investigate its prognostic role and its relation with survival outcomes.

METHODS

A total of 78 FFPE specimens were recruited as follows: GBM (n = 58) and BND (n = 20) then analyzed for NDRG2 methylation using Methyl II quantitative PCR system. The sensitivity and specificity of methylation was detected using receiver operating characteristic (ROC) curve and the relation with clinicopathological criteria for GBM and response to treatment were studied. Survival patterns; progression free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier analyses.

RESULTS

Mean methylation NDRG2 level was significantly increased in GBM patients as compared to BND and its sensitivity and specificity were 96.55% and 95%, respectively with area under curve (AUC) equals 0.973. Among the clinical characteristic factors, mean methylation level reported significant difference with ECOG and tumor site. Survival out comes revealed that NDRG2 methylation increased with worse PFS and OS at significant level (long rank test X2 = 13.3, p < .0001; and X2 = 7.1, p = .008, respectively).

CONCLUSION

Current findings highlight the importance of studying DNA methylation of NDRG2 as a key factor to understand the role of epigenetic alterations in GBM.

Anticancer Effect of E26 Transformation-Specific Homologous Factor through the Induction of Senescence and the Inhibition of Epithelial-Mesenchymal Transition in Triple-Negative Breast Cancer Cells

The aim of the present study was to evaluate the effect of ETS homologous factor (EHF) in malignant breast cancer cells. The overexpression and knockdown of the EHF gene in human and mouse breast cancer cells were performed, and the TCGA dataset and Q-omics were analyzed. We found that the tumor suppressor NDRG2 is correlated with EHF gene expression in triple-negative breast cancer cells, that EHF overexpression results in reduced cell proliferation and that apoptosis is promoted by the chemotherapeutic reagent treatment of EHF-overexpressing cells. By EHF overexpression, senescence-associated β-galactosidase activity and p21WAF1/CIP1 expression were increased, suggesting that EHF may induce cellular senescence. In addition, the overexpression of EHF reduced the migratory ability and inhibited epithelial-mesenchymal transition (EMT). Furthermore, EHF inhibited the phosphorylation of STAT3. The overexpression of EHF also reduced the tumor size, and lung metastasis in vivo. At the tumor site, β-galactosidase activity was increased by EHF. Finally, the Kaplan-Meier-plotter analysis showed that TNBC patients with a high expression of EHF had a longer relapse-free survival rate. Our findings demonstrated that EHF inhibits breast tumor progression by inducing senescence and regulating EMT in TNBC cells.

The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics

Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.

The potential role of miRNAs in the pathogenesis of adrenocortical carcinoma - A focus on signaling pathways interplay

Adrenocortical carcinoma (ACC) is a highly malignant infrequent tumor with a dismal prognosis. microRNAs (miRNAs, miRs) are crucial in post-transcriptional gene expression regulation. Due to their ability to regulate multiple gene networks, miRNAs are central to the hallmarks of cancer, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, replicative immortality, induction/access to the vasculature, activation of invasion and metastasis, reprogramming of cellular metabolism, and avoidance of immune destruction. ACC represents a singular form of neoplasia associated with aberrations in the expression of evolutionarily conserved short, non-coding RNAs. Recently, the role of miRNAs in ACC has been examined extensively despite the disease's rarity. Hence, the current review is a fast-intensive track elucidating the potential role of miRNAs in the pathogenesis of ACC besides their association with the survival of ACC.

Oxygen-Generating Biomaterials for Translational Bone Regenerative Engineering

Successful regeneration of critical-size defects remains one of the significant challenges in regenerative engineering. These large-scale bone defects are difficult to regenerate and are often reconstructed with matrices that do not provide adequate oxygen levels to stem cells involved in the regeneration process. Hypoxia-induced necrosis predominantly occurs in the center of large matrices since the host tissue's local vasculature fails to provide sufficient nutrients and oxygen. Indeed, utilizing oxygen-generating materials can overcome the central hypoxic region, induce tissue in-growth, and increase the quality of life for patients with extensive tissue damage. This article reviews recent advances in oxygen-generating biomaterials for translational bone regenerative engineering. We discussed different oxygen-releasing and delivery methods, fabrication methods for oxygen-releasing matrices, biology, oxygen's role in bone regeneration, and emerging new oxygen delivery methods that could potentially be used for bone regenerative engineering.

NDRG1 Signaling Is Essential for Endothelial Inflammation and Vascular Remodeling

BACKGROUND

NDRG-1 (N-myc downstream-regulated gene 1) is a member of NDRG family that plays essential roles in cell differentiation, proliferation, and stress responses. Although the expression of NDRG1 is regulated by fluid shear stress, its roles in vascular biology remain poorly understood. The purpose of the study is to determine the functional significance of NDRG1 in vascular inflammation and remodeling.

METHODS AND RESULTS

By using quantitative polymerase chain reaction, western blot, and immunohistochemistry, we demonstrate that the expression of NDRG1 is markedly increased in cytokine-stimulated endothelial cells and in human and mouse atherosclerotic lesions. To determine the role of NDRG1 in endothelial activation, we performed loss-of-function studies using NDRG1 short hairpin RNA. Our results demonstrate that NDRG1 knockdown by lentivirus bearing NDRG1 short hairpin RNA substantially attenuates both IL-1β (interleukin-1β) and TNF-α (tumor necrosis factor-α)-induced expression of cytokines/chemokines and adhesion molecules. Intriguingly, inhibition of NDRG1 also significantly attenuates the expression of procoagulant molecules, such as PAI-1 (plasminogen activator inhibitor type 1) and TF (tissue factor), and increases the expression of TM (thrombomodulin) and t-PA (tissue-type plasminogen activator), thus exerting potent antithrombotic effects in endothelial cells. Mechanistically, we showed that NDRG1 interacts with orphan Nur77 (nuclear receptor) and functionally inhibits the transcriptional activity of Nur77 and NF-κB (nuclear factor Kappa B) in endothelial cells. Moreover, in NDRG1 knockdown cells, both cytokine-induced mitogen-activated protein kinase activation, c-Jun phosphorylation, and AP-1 (activator protein 1) transcriptional activity are substantially inhibited. Neointima and atherosclerosis formation induced by carotid artery ligation and arterial thrombosis were markedly attenuated in endothelial cell-specific NDRG1 knockout mice compared with their wild-type littermates.

CONCLUSIONS

Our results for the first time identify NDRG1 as a critical mediator implicated in regulating endothelial inflammation, thrombotic responses, and vascular remodeling, and suggest that inhibition of NDRG1 may represent a novel therapeutic strategy for inflammatory vascular diseases, such as atherothrombosis and restenosis.

Echocardiography phenotyping in murine genetic reference population of BXD strains reveals significant QTLs associated with cardiac function and morphology

The genetic reference population of recombinant inbred BXD mice has been derived from crosses between C57BL/6J and DBA/2J strains. The DBA/2J parent exhibits cardiomyopathy phenotypes, whereas C57BL/6J has normal heart. BXD mice are sequenced for studying genetic interactions in cardiomyopathies. The study aimed to assess cardiomyopathy traits in BXDs and investigate the quantitative genetic architecture of those traits. Echocardiography, blood pressure, and cardiomyocyte size parameters obtained from 44 strains of BXD family (n > 5/sex) at 4-5 mo of age were associated with heart transcriptomes and expression quantitative trait loci (eQTL) mapping was performed. More than twofold variance in ejection fraction (EF%), fractional shortening (FS%), left ventricular volumes (LVVols), internal dimensions (LVIDs), mass (LVM), and posterior wall (LVPW) thickness was found among BXDs. In male BXDs, eQTL mapping identified Ndrg4 on chromosome 8 QTL to be positively correlated with LVVol and LVID and negatively associated with cardiomyocyte diameter. In female BXDs, significant QTLs were found on chromosomes 7 and 3 to be associated with LVPW and EF% and FS%, respectively, and Josd2, Dap3, and Tpm3 were predicted as strong candidate genes. Our study found variable cardiovascular traits among BXD strains and identified multiple associated QTLs, suggesting an influence of genetic background on expression of echocardiographic and cardiomyocyte diameter traits. Increased LVVol and reduced EF% and FS% represented dilated cardiomyopathy, whereas increased LV mass and wall thickness indicated hypertrophic cardiomyopathy traits. The BXD family is ideal for identifying candidate genes, causal and modifier, that influence cardiovascular phenotypes.NEW & NOTEWORTHY This study aimed to establish a cardiac phenotype-genotype correlation in murine genetic reference population of BXD RI strains by phenotyping the echocardiography, blood pressure, and cardiomyocyte diameter traits and associating each collected phenotype with genetic background. Our study identified several QTLs and candidate genes that have significant association with cardiac hypertrophy, ventricular dilation, and function including systolic hyperfunction and dysfunction.

Lactate attenuates astrocytic inflammation by inhibiting ubiquitination and degradation of NDRG2 under oxygen-glucose deprivation conditions

BACKGROUND

Brain lactate concentrations are enhanced in response to cerebral ischemia and promote the formation of reactive astrocytes, which are major components of the neuroinflammatory response and functional recovery, following cerebral ischemia. NDRG2 is upregulated during reactive astrocyte formation. However, its regulation and function are unclear. We studied the relationship between lactate and NDRG2 in astrocytes under conditions of ischemia or oxygen-glucose deprivation (OGD).

METHODS

We examined astrocytic NDRG2 expression after middle cerebral artery occlusion (MCAO) using western blot and immunofluorescence staining. Under hypoxia conditions, we added exogenous L-lactate sodium (lactate) to cultured primary astrocytes to explore the effects of lactate on the ubiquitination modification of NDRG2. We profiled the transcriptomic features of NDRG2 silencing in astrocytes after 8 h of OGD conditions as well as exogenous lactate treatment by performing RNA-seq. Finally, we evaluated the molecular mechanisms of NDRG2 in regulating TNFα under OGD conditions using western blot and immunohistochemistry.

RESULTS

Reactive astrocytes strongly expressed NDRG2 in a rat model of MCAO. We also showed that lactate stabilizes astrocytic NDRG2 by inhibiting its ubiquitination. NDRG2 inhibition in astrocytes increased inflammation and upregulated immune-associated genes and signaling pathways. NDRG2 knockdown induced TNFα expression and secretion via c-Jun phosphorylation.

CONCLUSIONS

We revealed that under OGD conditions, lactate plays an important anti-inflammatory role and inhibits TNFα expression by stabilizing NDRG2, which is beneficial for neurological functional recovery. NDRG2 may be a new therapeutic target for cerebral ischemia.

Ali R, B. Ismail M. NDRG1 is being investigated as a possible bladder cancer biomarker in the Iraqi population

With 549,393 new cases recorded in 2018, bladder cancer is one of the most common malignancies worldwide. Urinary bladder cancer is the cause of about 3 percent of all new cancer diagnoses and 2.1 percent of all cancer deaths. This study aims to evaluate the efficiency of the N-myc downstream-regulated gene 1(NDRG1) as a biomarker for bladder cancer patients in the Iraqi population. One hundred individuals in the case-control study were enrolled and divided into two groups. The first group included 50 patients diagnosed with a bladder mass and investigated by undergoing cystoscopy examination for transurethral resection of bladder tumor (TURB). The second group included 50 healthy individuals who had normal bladder tissue. The results of the present study showed the highest level of (NDRG1) among cases with statically significant association (p=0.001). The ROC curve demonstrated that the protein level of (NDRG1) could distinguish disease patients from healthy individuals with a sensitivity of 96% and a specificity of 92%. Serum (NDRG1) protein is an efficient and noninvasive tumor marker for diagnosing bladder cancer. Keywords: N-myc downstream-regulated gene 1 (NDRG1), non-muscle-invasive bladder cancer (NMIBC), transurethral resection of bladder tumor (TURB).

Environmental oxygen affects ex vivo growth and proliferation of mesenchymal progenitors by modulating mitogen-activated protein kinase and mammalian target of rapamycin signaling

BACKGROUND AIMS

Stem and progenitor cells of hematopoietic and mesenchymal lineages reside in the bone marrow under low oxygen (O₂) saturation. O₂ levels used in ex vivo expansion of multipotent mesenchymal stromal cells (MSCs) affect proliferation, metabolism and differentiation.

METHODS

Using cell-based assays and transcriptome and proteome data, the authors compared MSC cultures simultaneously grown under a conventional 19.95% O₂ atmosphere or at 5% O₂.

RESULTS

In 5% O₂, MSCs showed better proliferation and higher self-renewal ability, most probably sustained by enhanced signaling activity of mitogen-activated protein kinase and mammalian target of rapamycin pathways. Non-oxidative glycolysis-based energy metabolism supported growth and proliferation in 5% O₂ cultures, whereas MSCs grown under 19.95% O₂ also utilized oxidative phosphorylation. Cytoprotection mechanisms used by cells under 5% O₂ differed from 19.95% O₂  suggesting differences in the triggers of cell stress between these two O₂  conditions.

CONCLUSIONS

Based on the potential benefits for the growth and metabolism of MSCs, the authors propose the use of 5% O₂ for MSC culture.

Irrespective of Plaque Activity, Multiple Sclerosis Brain Periplaques Exhibit Alterations of Myelin Genes and a TGF-Beta Signature

In a substantial share of patients suffering from multiple sclerosis (MS), neurological functions slowly deteriorate despite a lack of radiological activity. Such a silent progression, observed in either relapsing-remitting or progressive forms of MS, is driven by mechanisms that appear to be independent from plaque activity. In this context, we previously reported that, in the spinal cord of MS patients, periplaques cover large surfaces of partial demyelination characterized notably by a transforming growth factor beta (TGF-beta) molecular signature and a decreased expression of the oligodendrocyte gene NDRG1 (N-Myc downstream regulated 1). In the present work, we re-assessed a previously published RNA expression dataset in which brain periplaques were originally used as internal controls. When comparing the mRNA profiles obtained from brain periplaques with those derived from control normal white matter samples, we found that, irrespective of plaque activity, brain periplaques exhibited a TGF-beta molecular signature, an increased expression of TGFB2 (transforming growth factor beta 2) and a decreased expression of the oligodendrocyte genes NDRG1 (N-Myc downstream regulated 1) and MAG (myelin-associated glycoprotein). From these data obtained at the mRNA level, a survey of the human proteome allowed predicting a protein-protein interaction network linking TGFB2 to the down-regulation of both NDRG1 and MAG in brain periplaques. To further elucidate the role of NDRG1 in periplaque-associated partial demyelination, we then extracted the interaction network linking NDRG1 to proteins detected in human central myelin sheaths. We observed that such a network was highly significantly enriched in RNA-binding proteins that notably included several HNRNPs (heterogeneous nuclear ribonucleoproteins) involved in the post-transcriptional regulation of MAG. We conclude that both brain and spinal cord periplaques host a chronic process of tissue remodeling, during which oligodendrocyte myelinating functions are altered. Our findings further suggest that TGFB2 may fuel such a process. Overall, the present work provides additional evidence that periplaque-associated partial demyelination may drive the silent progression observed in a subset of MS patients.

Supplementation with Tex261 provides a possible preventive treatment for hypoxic pulmonary artery hypertension

Objectives: Pulmonary artery hypertension (PAH) is a serious disease for which there is no effective treatment. Its pathogenesis is complex and has not yet been clarified. Tex261 is a protein-coding gene whose functional enrichment nodes include the transporter activity of COP II. However, the role of Tex261 in PAH remains unknown. Methods: Sugen5416/Hypoxic PAH models were established, and pulmonary arteries (PAs) were isolated for proteomic sequencing. The binding sites between Hif-1α and Tex261 were verified by dual-luciferase reporter gene assay. Cell proliferation was detected by MTS and EdU assays. For determination of the preventive and therapeutic effects of Tex261, intratracheal instillation of adeno-associated virus (AVV6) with Tex261 vectors was performed. Results: Tex261 was screened according to the proteomic sequencing data. Hif-1α inhibited Tex261 promoter activity under hypoxia. Decreased Tex261 expression promoted PASMC proliferation. Tex261 regulated Sec23 via the Ndrg1-mediated Akt pathway. Tex261 overexpression improved the pressure and vessel remodeling of PAs induced by Sugen5416/hypoxia. Conclusion: Hypoxia suppressed Tex261 expression through Hif-1α activation. The decreased Tex261 could promote Ndrg1 and depress Akt activity and then inhibit Sec23 activity, which leads to cell proliferation and vessel remodeling. Elevated Tex261 has some preventive and therapeutic effects on rats with PAH.

The molecular activity of cannabidiol in the regulation of Nrf2 system interacting with NF-κB pathway under oxidative stress

Cannabidiol (CBD), the major non-psychoactive phytocannabinoid of Cannabis sativa L., is one of the most studied compounds in pharmacotherapeutic approaches to treat oxidative stress-related diseases such as cardiovascular, metabolic, neurodegenerative, and neoplastic diseases. The literature data to date indicate the possibility of both antioxidant and pro-oxidative effects of CBD. Thus, the mechanism of action of this natural compound in the regulation of nuclear factor 2 associated with erythroid 2 (Nrf2), which plays the role of the main cytoprotective regulator of redox balance and inflammation under oxidative stress conditions, seems to be particularly important. Moreover, Nrf2 is strongly correlated with the cellular neoplastic profile and malignancy, which in turn is critical in determining the cellular response induced by CBD under pathophysiological conditions. This paper summarizes the CBD-mediated pathways of regulation of the Nrf2 system by altering the expression and modification of both proteins directly involved in Nrf2 transcriptional activity and proteins involved in the relationship between Nrf2 and the nuclear factor kappa B (NF-κB) which is another redox-sensitive transcription factor.

N-myc downstream regulated gene 1 (ndrg1) functions as a molecular switch for cellular adaptation to hypoxia

Lack of oxygen (hypoxia and anoxia) is detrimental to cell function and survival and underlies many disease conditions. Hence, metazoans have evolved mechanisms to adapt to low oxygen. One such mechanism, metabolic suppression, decreases the cellular demand for oxygen by downregulating ATP-demanding processes. However, the molecular mechanisms underlying this adaptation are poorly understood. Here, we report on the role of ndrg1a in hypoxia adaptation of the anoxia-tolerant zebrafish embryo. ndrg1a is expressed in the kidney and ionocytes, cell types that use large amounts of ATP to maintain ion homeostasis. ndrg1a mutants are viable and develop normally when raised under normal oxygen. However, their survival and kidney function is reduced relative to WT embryos following exposure to prolonged anoxia. We further demonstrate that Ndrg1a binds to the energy-demanding sodium-potassium ATPase (NKA) pump under anoxia and is required for its degradation, which may preserve ATP in the kidney and ionocytes and contribute to energy homeostasis. Lastly, we show that sodium azide treatment, which increases lactate levels under normoxia, is sufficient to trigger NKA degradation in an Ndrg1a-dependent manner. These findings support a model whereby Ndrg1a is essential for hypoxia adaptation and functions downstream of lactate signaling to induce NKA degradation, a process known to conserve cellular energy.

The Function of N-Myc Downstream-Regulated Gene 2 (NDRG2) as a Negative Regulator in Tumor Cell Metastasis

N-myc downstream-regulated gene 2 (NDRG2) is a tumor-suppressor gene that suppresses tumorigenesis and metastasis of tumors and increases sensitivity to anti-cancer drugs. In this review, we summarize information on the clinicopathological characteristics of tumor patients according to NDRG2 expression in various tumor tissues and provide information on the metastasis inhibition-related cell signaling modulation by NDRG2. Loss of NDRG2 expression is a prognostic factor that correlates with TNM grade and tumor metastasis and has an inverse relationship with patient survival in various tumor patients. NDRG2 inhibits cell signaling, such as AKT-, NF-κB-, STAT3-, and TGF-β-mediated signaling, to induce tumor metastasis, and induces activation of GSK-3β which has anti-tumor effects. Although NDRG2 operates as an adaptor protein to mediate the interaction between kinases and phosphatases, which is essential in regulating cell signaling related to tumor metastasis, the molecular mechanism of NDRG2 as an adapter protein does not seem to be fully elucidated. This review aims to assist the research design regarding NDRG2 function as an adaptor protein and suggests NDRG2 as a molecular target to inhibit tumor metastasis and improve the prognosis in tumor patients.

Expression and clinicopathological significance of glucocorticoid receptor, SGK1, and NDRG1 in hormone-naïve prostate carcinoma

Glucocorticoid receptor (GR) has been implicated in prostate carcinoma growth and progression. Glucocorticoid receptor beta (GRβ) acts as an inhibitor of GR; however, its function is not well understood. Serum- and glucocorticoid-regulated kinase 1 (SGK1) is a GR-responsive gene that phosphorylates N-myc downstream-regulated gene 1 (NDRG1) and is involved in cancer growth and invasion. However, the expression of GR, GRβ, SGK1, and NDRG1 in prostate cancer and their relationship with clinicopathological and functional significance remain unknown. The association between the status of GR, GRβ, SGK1, and NDRG1 immunoreactivity and clinicopathological variables was analyzed in patients with prostate carcinoma to explore their clinical significance. In prostate carcinoma cases, the relative abundance of GR and NDRG1 immunoreactivity was inversely and significantly associated with the primary tumor stage (pT), while GR immunoreactivity was inversely and significantly associated with the Ki-67 score. The relative expression status of NDRG1 was significantly associated with that of GR. However, no significant correlation was observed between any of the clinicopathological parameters and GRβ and SGK1 expression. Our findings indicate that GR and NDRG1 expression status is correlated with clinicopathological features in patients with prostate cancer.

A splice altering variant in NDRG1 gene causes Charcot-Marie-Tooth disease, type 4D

Charcot-Marie-Tooth disease, type 4D (CMT4D) is a progressive, autosomal recessive form of CMT, characterized by distal muscle weakness and atrophy, foot deformities, severe motor sensory neuropathy, and sensorineural hearing impairment. Mutations in NDRG1 gene cause neuropathy in humans, dogs, and rodents. Here, we describe clinical and genetic features of a 17-year-old male with wasting of hand muscle and foot and severe motor neuropathy. Whole exome sequencing was carried out on the patient and his unaffected parents. We identified a novel deletion of nine nucleotides (c.537 + 2_537 + 10del) on the splice donor site of intron 8 in NDRG1 gene. The Sanger sequencing confirmed the segregation of this mutation in autosomal recessive inheritance. Furthermore, transcript analysis confirmed a splice defect and reveals using of an alternate cryptic splice donor site on the downstream intronic region. It resulted in an insertion of 42 nucleotides to exon 8 of NDRG1. Translation of the resulting transcript sequence revealed an insertion of 14 amino acids in-frame to the existing NDRG1 protein. This insertion is predicted to disrupt an alpha helix which is involved in protein-protein interactions in homologous proteins. Our study expands the clinical and genetic spectrum of CMT4D. The splice defect we found in this patient reveals a novel splice isoform of NDRG1 as the potential cause for the neuropathy observed in this patient.

Clinical Diagnostic and Prognostic Potential of NDRG1 and NDRG2 in Hepatocellular Carcinoma Patients

Background

Primary liver cancer is still the most common lethal malignancy. The N-myc downstream-regulated gene family (NDRG1–4) is a group of multifunctional proteins associated with carcinogenesis. However, systematic evaluation of the diagnostic and prognostic values of NDRG1 or NDRG2 expression in liver cancer is poorly investigated.

Method

The gene expression matrix of liver hepatocellular carcinoma (LIHC) was comprehensively analyzed by the “limma” and “Dseq2” R packages. The Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA) were used to identify the biological functional differences. A single-sample GSEA (ssGSEA) was conducted to quantify the extent of immune cell infiltration. Finally, the clinical and prognostic information of LIHC patients was systematically investigated using Kaplan–Meier analysis and logistic and Cox regression analysis.

Results

Compared with normal tissues, NDRG1 expression was higher, whereas NDRG2 expression was lower in tumor tissues (P <0.001). The area under the receiver operator characteristic curve (AUROC) of NDRG1 and NDRG2 for LIHC was 0.715 and 0.799, respectively. Kaplan–Meier analysis revealed that NDRG1 and NDRG2 were independent clinical prognostic biomarkers for the overall survival (OS, P = 0.001 and 2.9e−06), progression-free interval (PFI, P = 0.028 and 0.005) and disease-specific survival (DSS, P = 0.027 and P <0.001). The C-indexes and calibration plots of the nomogram suggest that NDRG1 and NDRG2 have an effective predictive performance for OS (C-index: 0.676), DSS (C-index: 0.741) and PFI (C-index: 0.630) of liver cancer patients. The mutation rate of NDRG1 in liver cancer reached up to 14%, and DNA methylation levels of NDRG1 and NDRG2 promoters correlated significantly with clinical prognosis.

Conclusions

The mRNA expression and DNA methylation of NDRG superfamily members have the potential for LIHC diagnosis and prognosis via integrative analysis from multiple cohorts.

EZH2 regulates the balance between osteoclast and osteoblast differentiation to inhibit arthritis-induced bone destruction

Enhancer of zeste homolog 2 (EZH2) has been noted to contribute to the pathogenesis of autoimmune diseases. This study sought to investigate the mechanism of EZH2 in osteoclast (OCL) and osteoblast (OBL) differentiation (OCLD/OBLD) and bone destruction in RA. The animal model of collagen-induced arthritis (CIA) was established, followed by arthritis index (AI) scoring and histological staining, and measurements of inflammatory cytokines levels. The number of OCLs was detected via Tartrate-resistant acid phosphatase (TRAP) staining, and levels of OBL markers were determined by Western blot analysis. Trimethylated histone H3 at lysine 27 (H3K27me3) expression and its enrichment in the Ndrg2 promoter were detected. Collaborative experiments were performed with GSK-J1 or sh-Ndrg2 in CIA mice with EZH2 knockdown. EZH2 was upregulated while Ndrg2 was downregulated in knee joint tissues of CIA mice. Silencing EZH2 reduced AI scores, pathological injury of the knee joint, levels of inflammatory cytokines, and TRAP-positive cells, and increased protein levels of RUNX2 and BMP2. EZH2 promoted H3K27me3 level in the Ndrg2 promoter to inhibit Ndrg2 transcription. H3K27me3 upregulation or Ndrg2 downregulation reversed the role of silencing EZH2 in bone destruction. Overall, EZH2 repressed OBLD and promoted OCLD to aggravate bone destruction in CIA mice through H3K27me3/Ndrg2.

Glycogen Storage Disease Phenotypes Accompanying the Perturbation of the Methionine Cycle in NDRG3-Deficient Mouse Livers

N-Myc downstream regulated gene 3 (NDRG3) is a unique pro-tumorigenic member among NDRG family genes, mediating growth signals. Here, we investigated the pathophysiological roles of NDRG3 in relation to cell metabolism by disrupting its functions in liver. Mice with liver-specific KO of NDRG3 (Ndrg3 LKO) exhibited glycogen storage disease (GSD) phenotypes including excessive hepatic glycogen accumulation, hypoglycemia, elevated liver triglyceride content, and several signs of liver injury. They suffered from impaired hepatic glucose homeostasis, due to the suppression of fasting-associated glycogenolysis and gluconeogenesis. Consistently, the expression of glycogen phosphorylase (PYGL) and glucose-6-phosphate transporter (G6PT) was significantly down-regulated in an Ndrg3 LKO-dependent manner. Transcriptomic and metabolomic analyses revealed that NDRG3 depletion significantly perturbed the methionine cycle, redirecting its flux towards branch pathways to upregulate several metabolites known to have hepatoprotective functions. Mechanistically, Ndrg3 LKO-dependent downregulation of glycine N-methyltransferase in the methionine cycle and the resultant elevation of the S-adenosylmethionine level appears to play a critical role in the restructuring of the methionine metabolism, eventually leading to the manifestation of GSD phenotypes in Ndrg3 LKO mice. Our results indicate that NDRG3 is required for the homeostasis of liver cell metabolism upstream of the glucose–glycogen flux and methionine cycle and suggest therapeutic values for regulating NDRG3 in disorders with malfunctions in these pathways.

A Tumor Suppressor Gene, N-myc Downstream-Regulated Gene 1 (NDRG1), in Gliomas and Glioblastomas

The development of potent and selective therapeutic approaches to glioblastoma (GBM) requires the identification of molecular pathways that critically regulate the survival and proliferation of GBM. Glioblastoma stem-like cells (GSCs) possess stem-cell-like properties, self-renewal, and differentiation into multiple neural cell lineages. From a clinical point of view, GSCs have been reported to resist radiation and chemotherapy. GSCs are influenced by the microenvironment, especially the hypoxic condition. N-myc downstream-regulated gene 1 (NDRG1) is a tumor suppressor with the potential to suppress the proliferation, invasion, and migration of cancer cells. Previous studies have reported that deregulated expression of NDRG1 affects tumor growth and clinical outcomes of patients with GBM. This literature review aimed to clarify the critical role of NDRG1 in tumorigenesis and acquirement of resistance for anti-GBM therapies, further to discussing the possibility and efficacy of NDRG1 as a novel target of treatment for GBM. The present review was conducted by searching the PubMed and Scopus databases. The search was conducted in February 2022. We review current knowledge on the regulation and signaling of NDRG1 in neuro-oncology. Finally, the role of NDRG1 in GBM and potential clinical applications are discussed.

Prognostic and biological role of the N-Myc downstream-regulated gene family in hepatocellular carcinoma

BACKGROUND

The N-Myc downstream-regulated gene (NDRG) family is comprised of four members (NDRG1-4) involved in various important biological processes. However, there is no systematic evaluation of the prognostic of the NDRG family in hepatocellular carcinoma (HCC).

AIM

To analyze comprehensively the biological role of the NDRG family in HCC.

METHODS

The NDRG family expression was explored using The Cancer Genome Atlas. DNA methylation interactive visualization database was used for methylation analysis of the NDRG family. The NDRG family genomic alteration was assessed using the cBioPortal. Single-sample Gene Set Enrichment Analysis was used to determine the degree of immune cell infiltration in tumors.

RESULTS

NDRG1 and NDRG3 were up-regulated in HCC, while NDRG2 was down-regulated. Consistent with expression patterns, high expression of NDRG1 and NDRG3 was associated with poor survival outcomes (P < 0.05). High expression of NDRG2 was associated with favorable survival (P < 0.005). An NDRG-based signature that statistically stratified the prognosis of the patients was constructed. The percentage of genetic alterations in the NDRG family varied from 0.3% to 11.0%, and the NDRG1 mutation rate was the highest. NDRG 1-3 expression was associated with various types of infiltrated immune cells. Gene ontology analysis revealed that organic acid catabolism was the most important biological process related to the NDRG family. Gene Set Enrichment Analysis showed that metabolic, proliferation, and immune-related gene sets were enriched during NDRG1 and NDRG3 high expression and NDRG2 low expression.

CONCLUSION

Overexpression of NDRG1 and NDRG3 and down-expression of NDRG2 are correlated with poor overall HCC prognosis. Our results may provide new insights into the indispensable role of NDRG1, 2, and 3 in the development of HCC and guide a promising new strategy for treating HCC.

Regulation of tumor-associated macrophage (TAM) differentiation by NDRG2 expression in breast cancer cells

Macrophages are a major cellular component of innate immunity and are mainly known to have phagocytic activity. In the tumor microenvironment (TME), they can be differentiated into tumor-associated macrophages (TAMs). As the most abundant immune cells in the TME, TAMs promote tumor progression by enhancing angiogenesis, suppressing T cells and increasing immunosuppressive cytokine production. N-myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor gene, whose expression is down-regulated in various cancers. However, the effect of NDRG2 on the differentiation of macrophages into TAMs in breast cancer remains elusive. In this study, we investigated the effect of NDRG2 expression in breast cancer cells on the differentiation of macrophages into TAMs. Compared to tumor cell-conditioned medium (TCCM) from 4T1-mock cells, TCCM from NDRG2-overexpressing 4T1 mouse breast cancer cells did not significantly change the morphology of RAW 264.7 cells. However, TCCM from 4T1-NDRG2 cells reduced the mRNA levels of TAM-related genes, including MR1, IL-10, ARG1 and iNOS, in RAW 264.7 cells. In addition, TCCM from 4T1-NDRG2 cells reduced the expression of TAM-related surface markers, such as CD206, in peritoneal macrophages (PEM). The mRNA expression of TAM-related genes, including IL-10, YM1, FIZZ1, MR1, ARG1 and iNOS, was also downregulated by TCCM from 4T1-NDRG2 cells. Remarkably, TCCM from 4T1-NDRG2 cells reduced the expression of PD-L1 and Fra-1 as well as the production of GM-CSF, IL-10 and ROS, leading to the attenuation of T cell-inhibitory activity of PEM. These data showed that compared with TCCM from 4T1-mock cells, TCCM from 4T1-NDRG2 cells suppressed the TAM differentiation and activation. Collectively, these results suggest that NDRG2 expression in breast cancer may reduce the differentiation of macrophages into TAMs in the TME.

N-myc downstream regulated family member 1 (NDRG1) is enriched in myelinating oligodendrocytes and impacts myelin degradation in response to demyelination

The N-myc downstream regulated gene family member 1 (NDRG1) is a gene whose mutation results in peripheral neuropathy with central manifestations. While most of previous studies characterized NDRG1 role in Schwann cells, the detection of central nervous system symptoms and the identification of NDRG1 as a gene silenced in the white matter of multiple sclerosis brains raise the question regarding its role in oligodendrocytes. Here, we show that NDRG1 is enriched in oligodendrocytes and myelin preparations, and we characterize its expression using a novel reporter mouse (TgNdrg1-EGFP). We report NDRG1 expression during developmental myelination and during remyelination after cuprizone-induced demyelination of the adult corpus callosum. The transcriptome of Ndrg1-EGFP+ cells further supports the identification of late myelinating oligodendrocytes, characterized by expression of genes regulating lipid metabolism and bioenergetics. We also generate a lineage specific conditional knockout (Olig1^cre/+ ;Ndrg1^fl/fl ) line to study its function. Null mice develop normally, and despite similar numbers of progenitor cells as wild type, they have fewer mature oligodendrocytes and lower levels of myelin proteins than controls, thereby suggesting NDRG1 as important for the maintenance of late myelinating oligodendrocytes. In addition, when control and Ndrg1 null mice are subject to cuprizone-induced demyelination, we observe a higher degree of demyelination in the mutants. Together these data identify NDRG1 as an important molecule for adult myelinating oligodendrocytes, whose decreased levels in the normal appearing white matter of human MS brains may result in greater susceptibility of myelin to damage.

LDHA mediated degradation of extracellular matrix is a potential target for the treatment of aortic dissection

Aortic dissection (AD) is a disease with high mortality and lacks effective drug treatment. Recent studies have shown that the development of AD is closely related to glucose metabolism. Lactate dehydrogenase A (LDHA) is a key glycolytic enzyme and plays an important role in cardiovascular disease. However, the role of LDHA in the progression of AD remains to be elucidated. Here, we found that the level of LDHA was significantly elevated in AD patients and the mouse model established by BAPN combined with Ang II. In vitro, the knockdown of LDHA reduced the growth of human aortic vascular smooth muscle cells (HAVSMCs), glucose consumption, and lactate production induced by PDGF-BB. The overexpression of LDHA in HAVSMCs promoted the transformation of HAVSMCs from contractile phenotype to synthetic phenotype, and increased the expression of MMP2/9. Mechanistically, LDHA promoted MMP2/9 expression through the LDHA-NDRG3-ERK1/2-MMP2/9 pathway. In vivo, Oxamate, LDH and lactate inhibitor, reduced the degradation of elastic fibers and collagen deposition, inhibited the phenotypic transformation of HAVSMCs from contractile phenotype to synthetic phenotype, reduced the expression of NDRG3, p-ERK1/2, and MMP2/9, and delayed the progression of AD. To sum up, the increase of LDHA promotes the production of MMP2/9, stimulates the degradation of extracellular matrix (ECM), and promoted the transformation of HAVSMCs from contractile phenotype to synthetic phenotype. Oxamate reduced the progression of AD in mice. LDHA may be a therapeutic target for AD.

NDRG4 Alleviates Myocardial Infarction-Induced Apoptosis through the JAK2/STAT3 Pathway

OBJECTIVE

At present, studies have confirmed that NDRG4 is specifically expressed in the heart, while its effect on the heart is still unclear. This study is to explore the effect of NDRG4 on cardiomyocyte apoptosis caused by acute myocardial infarction (AMI).

METHODS

Twenty SD rats were randomly divided into Sham (left anterior descent of heart without ligation) and AMI groups. In this study, coronary artery ligation was used to establish an AMI model, and the AMI model was verified by auxiliary examination and pathological examination. Besides, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB) was used to detect the expression level of Bax and Bcl-2 in heart tissues, and NDRG mRNA levels in tissues were also detected. qRT-PCR technology was used to verify the transfection efficiency of NDRG4 in H9C2 cells, and the change of apoptosis level of H9C2 cells was detected by Cell Counting Kit-8 (CCK-8) assay and TUNEL staining; besides, the expression level of apoptosis-related factors was detected by WB and qRT-PCR technology. Simultaneously with the modeling of rats, we injected adenovirus (Ad) into the heart tissue and examined the structural and functional changes of the rat heart. Then, WB technology was used to detect the expression level of the JAK2/STAT3 signaling pathway.

RESULTS

The heart function and heart structure of rats in the MI group were dramatically worse, and the expression level of NDRG4 was also dramatically reduced. The overexpression of NDRG4 in H9C2 cells can effectively inhibit the ischemia/hypoxia- (I/H-) induced decrease in cell viability and increase in apoptosis rate and inhibit the increase in Bax/Bcl-2 ratio. Moreover, overexpression of NDRG4 in heart tissue can effectively improve the cardiac function and structural destruction caused by MI. In addition, NDRG4 can inhibit JAK2/STAT3 pathway activation.

CONCLUSION

The expression of NDRG4 in the MI tissue of rats was suppressed, while overexpression of NDRG4 by injection of Ad can obviously protect the rat heart. Furthermore, overexpression of NDRG4 in H9C2 cells can effectively inhibit the I/H-induced decrease in cell viability and increase in apoptosis rate, and this may be related to the inhibition of the JAK2/STAT3 signaling pathway.

MiR-483 Promotes Colorectal Cancer Cell Biological Progression by Directly Targeting NDRG2 through Regulation of the PI3K/AKT Signaling Pathway and Epithelial-to-Mesenchymal Transition

BACKGROUND

Colorectal cancer is the third frequent tumor in the whole world. MiR-483, located at the 11p15.5 locus, acts as an oncogene in multiple tumors. The purpose of this study is to explore the important roles of miR-483 in colorectal cancer.

MATERIALS AND METHODS

RT-qPCR and western blot were applied to calculate the mRNA levels of miR-483 and genes. The Kaplan-Meier method was conducted to calculate the survival of patients with colorectal cancer. The proliferation and invasive abilities were measured by Methyl Thiazolyl Tetrazolium (MTT) and transwell assays.

RESULTS

MiR-483 was upregulated in colorectal cancer tissues, and the upregulation of miR-483 predicted poor prognosis of colorectal cancer patients. NDRG2 was a target gene of miR-483 in colorectal cancer. Furthermore, miR-483 has been reported to promote colorectal cancer cell proliferation and invasion through targeting NDRG2 by the PI3K/AKT pathway and epithelial-to-mesenchymal transition (EMT). In addition, the overexpression of miR-483 promoted xenograft growth of LOVO cells.

CONCLUSION

MiR-483 promoted cell proliferation through the NDRG2/PI3K/AKT pathway and invasion-mediated EMT in colorectal cancer. In view of the multiple mechanisms of molecular immunotherapy, it is necessary to further study the relationship between miR-483 and colorectal cancer, so as to find a more direct and effective treatment method to prevent colorectal cancer.

Chromothripsis is a frequent event and underlies typical genetic changes in early T-cell precursor lymphoblastic leukemia in adults

Chromothripsis is a mitotic catastrophe that arises from multiple double strand breaks and incorrect re-joining of one or a few chromosomes. We report on incidence, distribution, and features of chromothriptic events in T-cell acute lymphoblastic leukemias (T-ALL). SNP array was performed in 103 T-ALL (39 ETP/near ETP, 59 non-ETP, and 5 with unknown stage of differentiation), including 38 children and 65 adults. Chromothripsis was detected in 11.6% of all T-ALL and occurred only in adult cases with an immature phenotype (12/39 cases; 30%). It affected 1 to 4 chromosomes, and recurrently involved chromosomes 1, 6, 7, and 17. Abnormalities of genes typically associated with T-ALL were found at breakpoints of chromothripsis. In addition, it gave rise to new/rare alterations, such as, the SFPQ::ZFP36L2 fusion, reported in pediatric T-ALL, deletions of putative suppressors, such as IKZF2 and CSMD1, and amplification of the BCL2 gene. Compared to negative cases, chromothripsis positive T-ALL had a significantly higher level of MYCN expression, and a significant downregulation of RGCC, which is typically induced by TP53 in response to DNA damage. Furthermore we identified mutations and/or deletions of DNA repair/genome stability genes in all cases, and an association with NUP214 rearrangements in 33% of cases.

NDRG2 Expression in Breast Cancer Cells Downregulates PD-L1 Expression and Restores T Cell Proliferation in Tumor-Coculture

Simple Summary

N-myc downstream-regulated gene 2 (NDRG2) is a candidate tumor suppressor in various cancers, including breast cancer. Increased expression of programmed death ligand 1 (PD-L1) is frequently observed in human cancers. Despite its role in cancer cells, the effects of NDRG2 on PD-L1 expression and PD-L1-PD-1 pathway disruption have not been investigated. We demonstrated that NDRG2 overexpression inhibits PD-L1 expression in human breast cancer cells. Blocking T cell proliferation by coculture with 4T1 mouse tumor cells that express high levels of PD-L1 could be significantly reversed by NDRG2 overexpression in the same tumor cells. NDRG2 knockdown in NDRG2-transfected cells elicited the upregulation of PD-L1 expression and accelerated the inhibition of T cell proliferation. These findings were confirmed from The Cancer Genome Atlas (TCGA) data that PD-L1 expression in basal and triple-negative breast cancer (TNBC) patients, but not in luminal A or B cancer patients, was negatively correlated with the NDRG2 expression.

Abstract

(1) Background: The aim of the present study was to evaluate the effect of NDRG2 expression in regulating PD-L1 or PD-L2 on malignant breast cancer cells. (2) Methods: Overexpression and knockdown of the NDRG2 gene in human and mouse cancer cells were applied and quantitative real-time PCR and Western blot analysis were performed. T cell proliferation and TCGA analysis were conducted to validate negative correlation of the PD-L1 expression with the NDRG2 expression. (3) Results: We found that NDRG2 overexpression inhibits PD-L1 expression in human breast cancer cells through NF-κB signaling. NDRG2 overexpression in 4T1 mouse breast cancer cells followed by PD-L1 downregulation could block the suppressive activity of cancer cells on T cell proliferation and knockdown of NDRG2 expression enhanced the expression of PD-L1, leading to the inhibition of T cell proliferation by tumor cell coculture. Finally, we confirmed from TCGA data that PD-L1 expression in basal and triple-negative breast cancer patients was negatively correlated with the expression of NDRG2. Intriguingly, linear regression analysis using TNBC cell lines showed that the PD-L1 level was negatively associated with the NDRG2 expression level. (4) Conclusions: Our findings demonstrate that NDRG2 expression is instrumental in suppressing PD-L1 expression and restoring PD-L1-inhibited T cell proliferation activity in TNBC cells.

Experimental study of the effects of hypoxia simulator on osteointegration of titanium prosthesis in osteoporotic rats

Background

Poor osseointegration is the key reason for implant failure after arthroplasty,whether under osteoporotic or normal bone conditions. To date, osseointegration remains a major challenge. Recent studies have shown that deferoxamine (DFO) can accelerate osteogenesis by activating the hypoxia signaling pathway. The purpose of this study was to test the following hypothesis: after knee replacement, intra-articular injection of DFO will promote osteogenesis and osseointegration with a 3D printed titanium prosthesis in the bones of osteoporotic rats.

Materials and methods

Ninety female Sprague–Dawley rats were used for the experiment. Ten rats were used to confirm the successful establishment of the osteoporosis model: five rats in the sham operation group and five rats in the ovariectomy group. After ovariectomy and knee arthroplasty were performed, the remaining 80 rats were randomly divided into DFO and control groups (n = 40 per group). The two groups were treated by intraarticular injection of DFO and saline respectively. After 2 weeks, polymerase chain reaction (PCR) and immunohistochemistry were used to evaluate the levels of HIF-1a, VEGF, and CD31. HIF-1a and VEGF have been shown to promote angiogenesis and bone regeneration, and CD31 is an important marker of angiogenesis. After 12 weeks, the specimens were examined by micro-computed tomography (micro-CT), biomechanics, and histopathology to evaluate osteogenesis and osseointegration.

Results

The results of PCR showed that the mRNA levels of VEGF and CD31 in the DFO group were significantly higher than those in the control group. The immunohistochemistry results indicated that positive cell expression of HIF-1a, VEGF, and CD31 in the DFO group was also higher. Compared with the control group, the micro-CT parameters of BMD, BV/TV, TB. N, and TB. Th were significantly higher. The maximal pull-out force and the bone-to-implant contact value were also higher.

Conclusions

The local administration of DFO, which is used to activate the HIF-1a signaling pathway, can promote osteogenesis and osseointegration with a prosthesis in osteoporotic bone.

Lipid droplets are beneficial for rabies virus replication by facilitating viral budding

Rabies is an old zoonotic disease caused by rabies virus (RABV), but the pathogenic mechanism of RABV is still not completely understood. Lipid droplets have been reported to play a role in pathogenesis of several viruses. However, its role on RABV infection remains unclear. Here, we initially found that RABV infection upregulated lipid droplet (LD) production in multiple cells and mouse brains. After the treatment of atorvastatin, a specific inhibitor of LD, RABV replication in N2a cells decreased. Then we found that RABV infection could upregulate N-myc downstream regulated gene-1 (NDRG1), which in turn enhance the expression of diacylglycerol acyltransferase 1/2 (DGAT1/2). DGAT1/2 could elevate cellular triglycerides synthesis and ultimately promote intracellular LD formation. Furthermore, we found that RABV-M and RABV-G, which were mainly involved in the viral budding process, could colocalize with LDs, indicating that RABV might utilize LDs as a carrier to facilitate viral budding and eventually increase virus production. Taken together, our study reveals that lipid droplets are beneficial for RABV replication and their biogenesis is regulated via NDRG1-DGAT1/2 pathway, which provides novel potential targets for developing anti-RABV drugs. IMPORTANCE Lipid droplets have been proven to play an important role in viral infections, but its role in RABV infection has not yet been elaborated. Here, we find that RABV infection upregulates the generation of LDs by enhancing the expression of N-myc downstream regulated gene-1 (NDRG1). Then NDRG1 elevated cellular triglycerides synthesis by increasing the activity of diacylglycerol acyltransferase 1/2 (DGAT1/2), which promotes the biogenesis of LDs. RABV-M and RABV-G, which are the major proteins involved in viral budding, could utilize LDs as a carrier and transport to cell membrane, resulting in enhanced virus budding. Our findings will extend the knowledge of lipid metabolism in RABV infection and help to explore potential therapeutic targets for RABV.

Differential expression and hypoxia-mediated regulation of the N-myc downstream regulated gene family

Many organisms rely on oxygen to generate cellular energy (adenosine triphosphate or ATP). During severe hypoxia, the production of ATP decreases, leading to cell damage or death. Conversely, excessive oxygen causes oxidative stress that is equally damaging to cells. To mitigate pathological outcomes, organisms have evolved mechanisms to adapt to fluctuations in oxygen levels. Zebrafish embryos are remarkably hypoxia-tolerant, surviving anoxia (zero oxygen) for hours in a hypometabolic, energy-conserving state. To begin to unravel underlying mechanisms, we analyze here the distribution of the N-myc Downstream Regulated Gene (ndrg) family, ndrg1-4, and their transcriptional response to hypoxia. These genes have been primarily studied in cancer cells and hence little is understood about their normal function and regulation. We show here using in situ hybridization that ndrgs are expressed in metabolically demanding organs of the zebrafish embryo, such as the brain, kidney, and heart. To investigate whether ndrgs are hypoxia-responsive, we exposed embryos to different durations and severity of hypoxia and analyzed transcript levels. We observed that ndrgs are differentially regulated by hypoxia and that ndrg1a has the most robust response, with a ninefold increase following prolonged anoxia. We further show that this treatment resulted in de novo expression of ndrg1a in tissues where the transcript is not observed under normoxic conditions and changes in Ndrg1a protein expression post-reoxygenation. These findings provide an entry point into understanding the role of this conserved gene family in the adaptation of normal cells to hypoxia and reoxygenation.

N-myc Downstream-Regulated Gene 2 (NDRG2) Function as a Positive Regulator of Apoptosis: A New Insight into NDRG2 as a Tumor Suppressor

N-myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor gene that increases tumor sensitivity to anticancer drugs, slows tumor progression, and inhibits metastasis. NDRG2 is suppressed in various aggressive tumor positions, whereas NDRG2 expression is associated with patient prognosis, such as an improved survival rate. In this review, we summarize the tumor suppressor mechanism of NDRG2 and provide information on the function of NDRG2 concerning the susceptibility of cells to apoptosis. NDRG2 increases the susceptibility to apoptosis in various physiological environments of cells, such as development, hypoxia, nutrient deprivation, and cancer drug treatment. Although the molecular and cell biological mechanisms of NDRG2 have not been fully elucidated, we provide information on the mechanisms of NDRG2 in relation to apoptosis in various environments. This review can assist the design of research regarding NDRG2 function and suggests the potential of NDRG2 as a molecular target for cancer patients.

miRNA Clusters with Up-Regulated Expression in Colorectal Cancer

Simple Summary

As miRNAs show the capacity to be used as CRC biomarkers, we analysed experimentally validated data about frequently up-regulated miRNA clusters in CRC tissue. We identified 15 clusters that showed increased expression in CRC: miR-106a/363, miR-106b/93/25, miR-17/92a-1, miR-181a-1/181b-1, miR-181a-2/181b-2, miR-181c/181d, miR-183/96/182, miR-191/425, miR-200c/141, miR-203a/203b, miR-222/221, mir-23a/27a/24-2, mir-29b-1/29a, mir-301b/130b and mir-452/224. Cluster positions in the genome are intronic or intergenic. Most clusters are regulated by several transcription factors, and by long non-coding RNAs. In some cases, co-expression of miRNA with other cluster members or host gene has been proven. miRNA expression patterns in cancer tissue, blood and faeces were compared. The members of the selected clusters target 181 genes. Their functions and corresponding pathways were revealed with the use of Panther analysis. Clusters miR-17/92a-1, miR-106a/363, miR-106b/93/25 and miR-183/96/182 showed the strongest association with metastasis occurrence and poor patient survival, implicating them as the most promising targets of translational research.

Abstract

Colorectal cancer (CRC) is one of the most common malignancies in Europe and North America. Early diagnosis is a key feature of efficient CRC treatment. As miRNAs can be used as CRC biomarkers, the aim of the present study was to analyse experimentally validated data on frequently up-regulated miRNA clusters in CRC tissue and investigate their members with respect to clinicopathological characteristics of patients. Based on available data, 15 up-regulated clusters, miR-106a/363, miR-106b/93/25, miR-17/92a-1, miR-181a-1/181b-1, miR-181a-2/181b-2, miR-181c/181d, miR-183/96/182, miR-191/425, miR-200c/141, miR-203a/203b, miR-222/221, mir-23a/27a/24-2, mir-29b-1/29a, mir-301b/130b and mir-452/224, were selected. The positions of such clusters in the genome can be intronic or intergenic. Most clusters are regulated by several transcription factors, and miRNAs are also sponged by specific long non-coding RNAs. In some cases, co-expression of miRNA with other cluster members or host gene has been proven. miRNA expression patterns in cancer tissue, blood and faeces were compared. Based on experimental evidence, 181 target genes of selected clusters were identified. Panther analysis was used to reveal the functions of the target genes and their corresponding pathways. Clusters miR-17/92a-1, miR-106a/363, miR-106b/93/25 and miR-183/96/182 showed the strongest association with metastasis occurrence and poor patient survival, implicating them as the most promising targets of translational research.

The Role of N-myc Downstream-Regulated Gene Family in Glioma Based on Bioinformatics Analysis

Glioma is the most common type of primary tumor in the central nervous system, and the molecular mechanisms remain elusive. N-myc downstream-regulated gene (NDRG) family is reported to take part in the pathogenesis of various diseases, including some preliminary exploration in glioma. However, there has been no bioinformatics analysis of NDRG family in glioma yet. Herein, we focused on the expression changes of NDRGs with their value in predicting patients' prognoses, upstream regulatory mechanisms (DNA mutation, DNA methylation, transcription factors, and microRNA regulation) and gene enrichment analysis based on co-expressed genes with data from public databases. Furthermore, the expression pattern of NDRGs was verified by the paired glioma and peritumoral samples in our institute. It was suggested that NDRGs were differentially expressed genes in glioma. In particular, the lower expression of NDRG2 or NDRG4 could serve as a predictor of higher grade tumor and poorer prognosis. Also, NDRGs might play a crucial role in signal transduction, energy metabolism, and cross-talk among cells in glioma, under the control of a complex regulatory network. This study enables us to better understand the role of NDRGs in glioma and with further research, it may contribute to the development of glioma treatment.

NDRG1 regulates osteosarcoma cells via mediating the mitochondrial function and CSCs differentiation

BACKGROUND

Cancer stem cells (CSCs) are mainly contributed to malignancy metastatic potential and resistant therapy of osteosarcoma (OS). The mitochondria-related apoptosis was generally accepted as the target of tumor therapy. However, the effect of N-myc downstream-regulated gene 1 (NDRG1) on CSCs and mitochondrial health in OS is still unknown.

METHODS

In OS cells, MG63 and U2OS, the siRNA of NDRG1 were conducted. Transwell, western blot, RT-qPCR, and mitochondria isolation were used to identify the effect of NDRG on OS cells and mitochondria. Moreover, the differentiation-related factors of CSCs were determined.

RESULTS

After downregulation of NDRG1, the cell viability, invasion ability decreased whereas cell apoptosis increased. The expressions profiles of fibronectin, vimentin, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP) 2, MMP9, and MMP13 were downregulated, but E-cadherin expression level was upregulated by NDRG1 siRNA. At the same time, cytochrome (Cyt) C levels were increased in cytosol with the decreasing in mitochondria after siRNA treatment. The mitochondrial membrane potential (MMPs) was declined, and the function of mitochondria was impeded. The expressions of uncoupling proteins (UCP) 2, voltage dependent anion channel (VDAC), peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α, and cyclooxygenase (COX) 2 were downregulated by NDRG1 silencing. Moreover, NDRG performed its function primarily through the Wnt pathway and could regulate the differentiation of osteosarcoma stem cells.

CONCLUSION

Silencing of NDRG1 could damage the function of mitochondria, promote the CSCs differentiation, alleviating OS progression.

Loss of enteric neuronal Ndrg4 promotes colorectal cancer via increased release of Nid1 and Fbln2

The N-Myc Downstream-Regulated Gene 4 (NDRG4), a prominent biomarker for colorectal cancer (CRC), is specifically expressed by enteric neurons. Considering that nerves are important members of the tumor microenvironment, we here establish different Ndrg4 knockout (Ndrg4-/- ) CRC models and an indirect co-culture of primary enteric nervous system (ENS) cells and intestinal organoids to identify whether the ENS, via NDRG4, affects intestinal tumorigenesis. Linking immunostainings and gastrointestinal motility (GI) assays, we show that the absence of Ndrg4 does not trigger any functional or morphological GI abnormalities. However, combining in vivo, in vitro, and quantitative proteomics data, we uncover that Ndrg4 knockdown is associated with enlarged intestinal adenoma development and that organoid growth is boosted by the Ndrg4-/- ENS cell secretome, which is enriched for Nidogen-1 (Nid1) and Fibulin-2 (Fbln2). Moreover, NID1 and FBLN2 are expressed in enteric neurons, enhance migration capacities of CRC cells, and are enriched in human CRC secretomes. Hence, we provide evidence that the ENS, via loss of Ndrg4, is involved in colorectal pathogenesis and that ENS-derived Nidogen-1 and Fibulin-2 enhance colorectal carcinogenesis.

Lactate Dehydrogenase A Governs Cardiac Hypertrophic Growth in Response to Hemodynamic Stress

The heart manifests hypertrophic growth in response to high blood pressure, which may decompensate and progress to heart failure under persistent stress. Metabolic remodeling is an early event in this process. However, its role remains to be fully characterized. Here, we show that lactate dehydrogenase A (LDHA), a critical glycolytic enzyme, is elevated in the heart in response to hemodynamic stress. Cardiomyocyte-restricted deletion of LDHA leads to defective cardiac hypertrophic growth and heart failure by pressure overload. Silencing of LDHA in cultured cardiomyocytes suppresses cell growth from pro-hypertrophic stimulation in vitro, while overexpression of LDHA is sufficient to drive cardiomyocyte growth. Furthermore, we find that lactate is capable of rescuing the growth defect from LDHA knockdown. Mechanistically, lactate stabilizes NDRG3 (N-myc downregulated gene family 3) and stimulates ERK (extracellular signal-regulated kinase). Our results together suggest that the LDHA/NDRG3 axis may play a critical role in adaptive cardiomyocyte growth in response to hemodynamic stress.

Dai et al. find that LDHA is significantly increased in the heart under hemodynamic stress, and cardiomyocyte-specific deletion of LDHA leads to severe cardiac dysfunction in response to pressure overload. LDHA may govern adaptive growth through elevation of NDRG3 and activation of ERK.

Key genes and drug delivery systems to improve the efficiency of chemotherapy

Cancer cells can develop resistance to anticancer drugs, thereby becoming tolerant to treatment through different mechanisms. The biological mechanisms leading to the generation of anticancer treatment resistance include alterations in transmembrane proteins, DNA damage and repair mechanisms, alterations in target molecules, and genetic responses, among others. The most common anti-cancer drugs reported to develop resistance to cancer cells include cisplatin, doxorubicin, paclitaxel, and fluorouracil. These anticancer drugs have different mechanisms of action, and specific cancer types can be affected by different genes. The development of drug resistance is a cellular response which uses differential gene expression, to enable adaptation and survival of the cell to diverse threatening environmental agents. In this review, we briefly look at the key regulatory genes, their expression, as well as the responses and regulation of cancer cells when exposed to anticancer drugs, along with the incorporation of alternative nanocarriers as treatments to overcome anticancer drug resistance.

Radiation-induced gastrointestinal syndrome is alleviated in NDRG2-deficient mice

Background

Radiation-induced gastrointestinal syndrome (GIS) often occurs after therapeutic or accidental exposure to high doses of radiation. Unfortunately, there are still no effective medical treatments for GIS. N-Myc downstream regulated gene 2 (NDRG2), is a tumor suppressor gene and promotes cell apoptosis and differentiation. The aim of our study was to identify the role of NDRG2 in the progression of GIS and explore the potential mechanism.

Methods

We generated Ndrg2^ΔG mice, lacking NDRG2 specifically in the intestinal epithelium. Survival analysis was performed to validate the effect of NDRG2 on GIS, and other common indicators (body weight loss and diarrhea) were used for the assessment of GIS. Enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) were conducted to obtain the expression of pro-inflammatory interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha (TNF-α). TUNNEL and western blotting were further adopted to determine the relationship between NDRG2 and apoptosis. Finally, we performed histology and immunohistochemistry assays to explore the morphological alternations and changes of proliferation-related molecules, including Ki-67 and proliferating cell nuclear antigen (PCNA).

Results

We found that after 8 gray of total body ɤ-irradiation (TBI), the deletion of NDRG2 in the intestine revealed longer survival time, considerably milder symptoms of GIS, and milder damage to jejunal tissue, compared with the WT mice. Moreover, the Ndrg2^ΔG mice significantly inhibited the expression of pro-inflammatory IL-1β, IL-6, and TNF-α, which were typically increased by irradiation. Apoptosis of the epithelial cells in the Ndrg2^ΔG mice was significantly milder while the ratio of proliferation cells was larger in the epithelium of mice 8 days after TBI when compared with the WT mice.

Conclusions

These findings all indicated that NDRG2 deficiency in the intestine protects mice against radiation-induced GIS mainly through promoting proliferation and suppressing apoptosis of epithelial cells.