NDRG1 deficiency attenuates fetal growth and the intrauterine response to hypoxic injury

Vasculogenic mimicry regulates immune infiltration and mutational status of the tumor microenvironment in breast cancer to influence tumor prognosis

BACKGROUND

Vasculogenic mimicry (VM) refers to the direct formation of microcirculatory ducts by invasive malignant tumors via cellular phenotypic transformation. However, there is a lack of VM-based biomarkers for breast cancer.

METHODS

We obtained transcriptomic expression data, single cell sequencing data, and clinical data of patients from The Cancer Genome Atlas Program (TCGA) database and GEO database, performed single cell analysis to obtain specific type annotations of breast cancer cells and analyzed their spatial expression analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) analyses as well as Gene Set Enrichment Analysis (GSEA) analyses were performed to clarify the biological pathways and tumor functional enrichment relationships of the major expressed genes of VM in the breast cancer bulk data specimens. VM biomarkers were constructed. Meanwhile, the relationship between VM scores and tumor immune infiltration in breast cancer was analyzed using MCPcounter and ssGSEA methods. In addition, we assessed the specific relationship between NDRG1, a key VM gene in breast cancer, and tumor colonization, adhesion and invasion by biological experiments in breast cancer cell lines.

RESULTS

The main cell types of breast cancer (BRCA) samples were annotated by single cell transcriptome analysis. Most of the VM-high group was present in epithelial cells, whereas the VM-low group was present in immune and stromal cells. Multiple tumor pathways such as TGFβ p53 and MAPK were closely associated with VM-mediated breast cancer infiltration and invasion. A prognostic model of breast cancer based on VM key genes was constituted. Prognostic stratification of breast cancer was successfully achieved for the TCGA-BRCA and GSE58812 datasets. Through immune infiltration analysis, we found that differential expression of VM markers was associated with multiple immune cell regulation. In MDA-MB-231 and MDA-MB-453 cell lines, we found that the NDRG1 gene significantly promoted colony formation of breast cancer cells.

CONCLUSION

Our constructed VM-related gene-based model of breast cancer biology holds promise for prognostic prediction and patient stratification of breast cancer. This may provide a potentially clinically valuable aid in promoting a deeper understanding of the biological regulation of VM in breast cancer and exploring the specific mechanisms of tumor angiogenesis and breast cancer development.

Maternal pre-pregnancy body mass index and offspring with overweight/obesity at preschool age: The possible role of epigenome-wide DNA methylation changes in cord blood

BACKGROUND

Epigenome-wide association studies have identified some DNA methylation sites associated with body mass index (BMI) or obesity. Studies in the Asian population are lacking.

OBJECTIVE

To examine the association of cord blood genome-wide DNA methylation (GWDm) changes with maternal pre-pregnancy BMI and children's BMI-z score at preschool age. Additionally, we also explored the genome-wide differentially methylated regions and differentially methylated probes between preschoolers with overweight/obesity and normal-weight counterparts.

METHODS

This two-stage study design included (1) a GWDm analysis of 30 mother-child pairs from 633 participants of the Zhuhai birth cohort with data on newborn cord blood, maternal pre-pregnancy BMI, and children's BMI at 3 years of age; and (2) a targeted validation analysis of the cord blood of ten children with overweight/obesity and ten matched controls to validate the CpG sites.

RESULTS

In the first stage, no significant CpG sites were found to be associated with children's BMI-z score at preschool age after FDR correction with the p-values of the CpG sites in FOXN3 (cg23501836) and ZNF264 (cg27437574) being close to 1 × 10^-6 . In the second stage, a significant difference of CpG sites in AHRR (chr5:355067-355068) and FOXN3 (chr14: 89630264-89630272 and chr14: 89630387-89630388) was found between the ten children with overweight/obesity and ten controls (p < 0.05). The CpG sites in FOXN3 (chr14:89630264-89630272 and chr14:89630295-89630296) and ZNF264 (chr19: 57703104-57703107 and chr19: 57703301-57703307) were associated with children's BMI-z score; and the CpG sites in FOXN3 (chr14: 89630264-89630272 and chr14: 89630387-89630388) were associated with maternal pre-pregnancy BMI.

CONCLUSIONS

DNA methylation in FOXN3 and AHRR is associated with overweight/obesity in preschool-aged children, and the methylation in FOXN3 and ZNF264 might be associated with children's BMI-z score. FOXN3 methylation may be associated with maternal pre-pregnancy BMI, suggesting its potential role in the children's BMI-z score or overweight/obesity. Our results provide novel insights into the mechanisms of children's obesity.

N-myc downstream regulated gene 1 inhibition of tumor progression in Caco2 cells

BACKGROUND

Invasion and migration are the irreversible stages of colorectal cancer (CRC). The key is to find a sensitive, reliable molecular marker that can predict the migration of CRC at an early stage. N-myc downstream regulated gene 1 (NDRG1) is a multifunctional gene that has been tentatively reported to have a strong relationship with tumor invasion and migration, however the current molecular role of NDRG1 in CRC remains unknown.

AIM

To explore the role of NDRG1 in the development of CRC.

METHODS

NDRG1 stably over-expressed Caco2 cell line was established by lentiviral infection and NDRG1 knock-out Caco2 cell line was established by CRISPR/Cas9. Furthermore, the mRNA and protein levels of NDRG1 in Caco2 cells after NDRG1 over-expression and knockout were detected by real-time polymerase chain reaction and western blot. The cell proliferation rate was measured by the cell counting kit-8 method; cell cycle and apoptosis were detected by flow cytometry; invasion and migration ability were detected by the 24-transwell method.

RESULTS

NDRG1 over-expression inhibited Caco2 proliferation and the cell cycle could be arrested at the G1/S phase when NDRG1 was over-expressed, while the number of cells in the G2 phase was significantly increased when NDRG1 was knocked out. This suggests that NDRG1 inhibited the proliferation of Caco2 cells by arresting the cell cycle in the G1/S phase. Our data also demonstrated that NDRG1 promotes early cell apoptosis. Invasion and migration of cells were extensively inhibited when NDRG1 was over-expressed.

CONCLUSION

NDRG1 inhibits tumor progression in Caco2 cells which may represent a potential novel therapeutic strategy for the treatment of CRC.

Placental hypoxia: What have we learnt from small animal models?

Intrauterine hypoxia is a feature of pregnancy complications, both at high altitude and sea level. To understand the placental response to reduced oxygen availability, small animal models of maternal inhalation hypoxia (MIH) or reduced uterine perfusion pressure (RUPP) may be utilised. The aim of this review was to compare the findings of those studies to identify the role of oxygen availability in adapting placental structural and functional phenotypes in relation to fetal outcome. It also sought to explore the evidence for the involvement of particular genes and protein signalling pathways in the placenta in mediating hypoxia driven alterations. The data available demonstrate that both MIH and RUPP can induce placental hypoxia, which affects placental structure and vascularity, as well as glucose, amino acid, calcium and possibly lipid transport capacity. In addition, changes have been observed in HIF, VEGF, insulin/IGF2, AMPK, mTOR, PI3K and PPARγ signalling, which may be key in linking together observed phenotypes under conditions of placental hypoxia. Many different manipulations have been examined, with varied outcomes depending on the intensity, timing and duration of the insult. Some manipulations have detrimental effects on placental phenotype, viability and fetal growth, whereas in others, the placenta appears to adapt to uphold fetal growth despite the challenge of low oxygen. Together these data suggest a complex response of the placenta to reduced oxygen availability, which links to changes in fetal outcomes. However, further work is required to explore the role of fetal sex, altered maternal physiology and placental molecular mechanisms to fully understand placental responses to hypoxia and their relevance for pregnancy outcome.

Pharmacological targeting and the diverse functions of the metastasis suppressor, NDRG1, in cancer

N-myc downstream regulated gene-1 (NDRG1) is a potent metastasis suppressor that is regulated by hypoxia, metal ions including iron, the free radical nitric oxide (NO^.), and various stress stimuli. This intriguing molecule exhibits diverse functions in cancer, inhibiting epithelial-mesenchymal transition (EMT), cell migration and angiogenesis by modulation of a plethora of oncogenes via cellular signaling. Thus, pharmacological targeting of NDRG1 signaling in cancer is a promising therapeutic strategy. Of note, novel anti-tumor agents of the di-2-pyridylketone thiosemicarbazone series, which exert the "double punch" mechanism by binding metal ions to form redox-active complexes, have been demonstrated to markedly up-regulate NDRG1 expression in cancer cells. This review describes the mechanisms underlying NDRG1 modulation by the thiosemicarbazones and the diverse effects NDRG1 exerts in cancer. As a major induction mechanism, iron depletion appears critical, with NO^. also inducing NDRG1 through its ability to bind iron and generate dinitrosyl-dithiol iron complexes, which are then effluxed from cells. Apart from its potent anti-metastatic role, several studies have reported a pro-oncogenic role of NDRG1 in a number of cancer-types. Hence, it has been suggested that NDRG1 plays pleiotropic roles depending on the cancer-type. The molecular mechanism(s) underlying NDRG1 pleiotropy remain elusive, but are linked to differential regulation of WNT signaling and potentially differential interaction with the tumor suppressor, PTEN. This review discusses NDRG1 induction mechanisms by metal ions and NO^. and both the anti- and possible pro-oncogenic functions of NDRG1 in multiple cancer-types and compares the opposite effects this protein exerts on cancer progression.

Genome-wide association studies for the number of animals born alive and dead in duroc pigs

Litter size is one of the most important economic traits for pig production as it is directly related to the production efficiency. As an important litter size trait in pigs, the number of piglets born alive at birth (NBA) receives widespread interests in the pig industry. However, traits of piglets born dead, including the number of stillborn piglets (NS) and the piglets mummified at birth (NM) should be noted to explain the loss of reproduction. Herein, in the present study, a total of 803 producing sows were sampled and 2807 farrowing records for NBA, NM, and NS traits were collected in a Duroc swine population. Subsequently, a genome-wide association study (GWAS) was performed for NBA, NS and NM in parity groups 1 to 5. In total, 10 putative regions were found associated with these traits. After stepwise conditional analyses around the putative regions, eight independent signals were ultimately identified for NBA, NS, and NM, and there were seven promising candidate genes related to these traits, including ARID1A, RXRG, NFATC4, ABTB2, GRAMD1B, NDRG1, and APC. Our findings contribute to the understanding of the significant genetic causes of piglets born alive and dead, and could have a positive effect on pig production efficiency and economic profits.

Lipoxin A4 Ameliorates Lipopolysaccharide-Induced A549 Cell Injury through Upregulation of N-myc Downstream-Regulated Gene-1

Background:

Lipoxin A4 (LXA4) can alleviate lipopolysaccharide (LPS)-induced acute lung injury (ALI) and acute respiratory distress syndrome through promoting epithelial sodium channel (ENaC) expression in lung epithelial cells. However, how LXA4 promote ENaC expression is still largely elusive. The present study aimed to explore genes and signaling pathway involved in regulating ENaC expression induced by LXA4.

Methods:

A549 cells were incubated with LPS and LXA4, or in combination, and analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) of ENaC-α/γ. Candidate genes affected by LXA4 were explored by transcriptome sequencing of A549 cells. The critical candidate gene was validated by qRT-PCR and Western blot analysis of A549 cells treated with LPS and LXA4 at different concentrations and time intervals. LXA4 receptor (ALX) inhibitor BOC-2 was used to test induction of candidate gene by LXA4. Candidate gene siRNA was adopted to analyze its influence on A549 viability and ENaC-α expression. Phosphoinositide 3-kinase (PI3K) inhibitor LY294002 was utilized to probe whether the PI3K signaling pathway was involved in LXA4 induction of candidate gene expression.

Results:

The A549 cell models of ALI were constructed and subjected to transcriptome sequencing. Among candidate genes, N-myc downstream-regulated gene-1 (NDRG1) was validated by real-time-PCR and Western blot. NDRG1 mRNA was elevated in a dose-dependent manner of LXA4, whereas BOC-2 antagonized NDRG1 expression induced by LXA4. NDRG1 siRNA suppressed viability of LPS-treated A549 cells (treatment vs. control, 0.605 ± 0.063 vs. 0.878 ± 0.083, P = 0.040) and ENaC-α expression (treatment vs. control, 0.458 ± 0.038 vs. 0.711 ± 0.035, P = 0.008). LY294002 inhibited NDRG1 (treatment vs. control, 0.459 ± 0.023 vs. 0.726 ± 0.020, P = 0.001) and ENaC-α (treatment vs. control, 0.236 ± 0.021 vs. 0.814 ± 0.025, P < 0.001) expressions and serum- and glucocorticoid-inducible kinase 1 phosphorylation (treatment vs. control, 0.442 ± 0.024 vs. 1.046 ± 0.082, P = 0.002), indicating the PI3K signaling pathway was involved in regulating NDRG1 expression induced by LXA4.

Conclusion:

Our research uncovered a critical role of NDRG1 in LXA4 alleviation of LPS-induced A549 cell injury through mediating PI3K signaling to restore ENaC expression.

Hypoxia and Placental Development

Hemochorial placentation is orchestrated through highly regulated temporal and spatial decisions governing the fate of trophoblast stem/progenitor cells. Trophoblast cell acquisition of specializations facilitating invasion and uterine spiral artery remodeling is a labile process, sensitive to the environment, and represents a process that is vulnerable to dysmorphogenesis in pathologic states. Hypoxia is a signal guiding placental development, and molecular mechanisms directing cellular adaptations to low oxygen tension are integral to trophoblast cell differentiation and placentation. Hypoxia can also be used as an experimental tool to investigate regulatory processes controlling hemochorial placentation. These developmental processes are conserved in mouse, rat, and human placentation. Consequently, elements of these developmental events can be modeled and hypotheses tested in trophoblast stem cells and in genetically manipulated rodents. Hypoxia is also a consequence of a failed placenta, yielding pathologies that can adversely affect maternal adjustments to pregnancy, fetal health, and susceptibility to adult disease. The capacity of the placenta for adaptation to environmental challenges highlights the importance of its plasticity in safeguarding a healthy pregnancy. Birth Defects Research 109:1309-1329, 2017.© 2017 Wiley Periodicals, Inc.

Review: Sexual dimorphism in the formation, function and adaptation of the placenta

Exposure of the embryo or fetus to perturbations in utero can result in intrauterine growth restriction, a primary risk factor for the development of adult disease. However, despite similar exposures, males and females often have altered disease susceptibility or progression from different stages of life. Fetal growth is largely mediated by the placenta, which, like the fetus is genetically XX or XY. The placenta and its associated trophoblast lineages originate from the trophectoderm (TE) of the early embryo. Rodent models (rat, mouse, spiny mouse), have been used extensively to examine placenta development and these have demonstrated the growth trajectory of the placenta in females is generally slower compared to males, and also shows altered adaptive responses to stressful environments. These placental adaptations are likely to depend on the type of stressor, duration, severity and the window of exposure during development. Here we describe the divergent developmental pathways between the male and female placenta contributing to altered differentiation of the TE derived trophoblast subtypes, placental growth, and formation of the placental architecture. Our focus is primarily genetic or environmental perturbations in rodent models which show altered placental responsiveness between sexes. We suggest that perturbations during early placental development may have greater impact on viability and growth of the female fetus whilst those occurring later in gestation may preferentially affect the male fetus. This may be of great relevance to human pregnancies which result from assisted reproductive technologies or complications such as pre-eclampsia and diabetes.

Role of hypoxia during nephrogenesis

Mammals develop in a physiologically hypoxic state, and the oxygen tension of different tissues in the embryo is precisely controlled. Deviation from normal oxygenation, such as what occurs in placental insufficiency, can disrupt fetal development. Several studies demonstrate that intrauterine hypoxia has a negative effect on kidney development. As nascent nephrons are forming from nephron progenitors in the nephrogenic zone, they are exposed to varying oxygen tension by virtue of the development of the renal vasculature. Thus, nephrogenesis may be linked to oxygen tension. However, the mechanism(s) by which this occurs remains unclear. This review focuses on what is known about molecular mechanisms active in physiological and pathological hypoxia and their effects on kidney development.

N-myc downstream-regulated gene 1 (NDRG1) mediates pomegranate juice protection from apoptosis in hypoxic BeWo cells but not in primary human trophoblasts

INTRODUCTION

N-Myc downstream-regulated gene 1 (NDRG1) expression is increased in placentas of human pregnancies with intrauterine growth restriction and in hypoxic cultured primary trophoblasts. We previously showed that elevated NDRG1 decreases trophoblast apoptosis induced by hypoxia. Separately, we found that pomegranate juice (PJ) decreases cell death induced by hypoxia in trophoblasts. Here, we test the hypothesis that PJ protects trophoblasts from hypoxia-induced apoptosis by modulating NDRG1 expression.

METHODS

Quantitative rtPCR was used to investigate the effects of PJ treatment on mRNA levels of 22 candidate genes involved in apoptosis, oxidative stress, and differentiation in trophoblasts. Western blotting and immunofluorescence were used to analyze NDRG1 protein levels. siRNA-mediated NDRG1 knockdown was used to investigate the role of NDRG1 in response to PJ in hypoxic BeWo choriocarcinoma cells and hypoxic cultured primary human trophoblasts.

RESULTS

The mRNA levels of eight genes were altered, with NDRG1 showing the largest response to PJ and thus, we pursued the role of NDRG1 here. PJ significantly increased NDRG1 protein expression in primary trophoblasts and in BeWo cells. Knockdown of NDRG1 in hypoxic BeWo cells in the presence of PJ yielded increased apoptosis. In contrast, knockdown of NDRG1 in hypoxic primary trophoblasts in the presence of PJ did not increase apoptosis.

DISCUSSION

We conclude that the PJ-mediated decrease in cell death in hypoxia is partially mediated by NDRG1 in BeWo cells but not in primary trophoblasts. The disparate effects of NDRG1 between BeWo cells and primary trophoblasts indicate caution is required when extrapolating from results obtained with cell lines to primary trophoblasts.

Fatty acid binding protein-4 is expressed in the mouse placental labyrinth, yet is dispensable for placental triglyceride accumulation and fetal growth

INTRODUCTION

Fatty Acid Binding Protein-4 (FABP4) is a member of a family of FABP proteins that regulate intracellular lipid trafficking in diverse tissues. We recently showed that FABP4 regulates triglyceride accumulation in primary human trophoblasts. To assess the function of placental FABP4 in vivo, we tested the hypothesis that FABP4 is expressed in the murine placenta, and regulates placenta triglyceride accumulation.

METHODS

C57Bl/6 wild type or Fabp4-null mice were time-bred, and fetuses and placentas harvested at different time points during pregnancy. Placental FABP4 expression was assessed at different gestational ages, using quantitative PCR, immunohistochemistry, immunofluorescence and western immunoblotting. FABPs expression was examined by RT-qPCR. Placental lipids were extracted using the Folch method and triglyceride levels determined using a colorimetric quantification kit.

RESULTS

Using immunohistochemistry, we found that FABP4 was expressed in the placental labyrinthine layer, predominantly in endothelial cells in association with CD31 positive fetal capillaries. The level of placental FABP4 mRNA and protein increased from E12.5 to E16.5 and slightly decreased at E18.5. Breeding of Fabp4 heterozygous mice resulted in embryonic genotypes that followed a Mendelian distribution and exhibited normal weight and morphology, triglyceride content, and expression of other FABP family members. Exposure to hypoxia (O2 = 12%) between E12.5-E18.5 did not uncover a difference between wild type and Fabp4-null mice.

CONCLUSIONS

FABP4 is expressed in the mouse placental labyrinth, with highest expression at E16.5. FABP4 is dispensable for feto-placental growth and placental lipid accumulation.