TR3 is involved in hypoxia-induced apoptosis resistance in lung cancer cells downstream of HIF-1α

NR4A1 suppresses breast cancer growth by repressing c-Fos-mediated lipid and redox dyshomeostasis

The specific function of NR4A1 as a transcriptional regulator in cancer remains unclear. Here we report the biological effect of NR4A1 in suppressing breast cancer (BC) growth. We found that NR4A1 deficiency was correlated with BC progression in the clinic. Genetic deletion of NR4A1 in BC cells significantly promoted cellular proliferation and tumor growth. Moreover, global metabolome screening indicated that the deletion of NR4A1 resulted in tumor lipid remodeling and phospholipid accumulation, which was accompanied by increases in fatty acid and lipid uptake. In addition, NR4A1 knockout induced oxidative stress that aggravated redox balance disruption. Mechanistically, transcriptomic and epigenomic analyses revealed that NR4A1 restrained BC cell proliferation by directly interacting with c-Fos and competitively inhibiting c-Fos binding to the promoter of the target gene PRDX6, which is involved in lipid and redox homeostasis. Notably, we confirmed that the treatment of BC cells with the selective NR4A1 agonist cytosporone B significantly activated the expression of NR4A1, followed by increased interaction between NR4A1 and c-Fos, thereby interfering with c-Fos-mediated transcriptional regulation of BC cell growth. Thus, NR4A1 plays a vital role in reducing the c-Fos-induced activation of downstream signaling cascades in BC, suggesting that agents that activate NR4A1 may be potential therapeutic strategies.

AIBP protects drug-induced liver injury by inhibiting MAPK-mediated NR4A1 expression

Drug-induced liver injury (DILI) is an important adverse drug reaction that can lead to acute liver failure or even death in severe cases. AIBP is a binding protein of apolipoprotein AI involved in lipid metabolism and maintenance of oxidative respiration in mitochondria, but its role in DILI is unclear. By constructing AIBP knockout mice, overexpressing and knocking down AIBP in cell lines, we established animal and cell models of DILI. Using western blotting and real-time qPCR assay, we explored the influence of AIBP in activation of mitogen-activated protein kinases (MAPK) signal pathways and possible targets. AIBP was downregulated during hepatocyte injury. AIBP deficient mice develop severe liver injury and more sensitive to drug-induced cell death. Overexpression of AIBP protects cells under APAP treatment. Furthermore, AIBP inhibits the activation of MAPK pathways, through which AIBP regulates NR4A1. These results suggest that AIBP is expected to become a valuable biomarker and therapeutic target in liver injury.

NR4A1-mediated regulation of lipid droplets in progesterone synthesis in goat luteal cells†

Nuclear receptor NR4A1 is a key factor in glycolipid metabolism and steroidogenesis, while lipid droplets serve as crucial dynamic organelles for lipid metabolism in luteal cells. To investigate the effects of NR4A1 on lipid droplet metabolism and progesterone (P4) synthesis in goat corpus luteum in vitro, luteal cells from the middle-cyclic corpus luteum were isolated and treated with Cytosporone B (CSNB, an agonist) or siRNA of NR4A1. Results showed that both low (1 μM) and high (50 μM) concentrations of CSNB promoted lipid droplet accumulation, while NR4A1 knockdown reduced lipid droplet content. CSNB increased while siNR4A1 decreased total cholesterol content; however, CSNB and siNR4A1 did not change triglyceride content. CSNB increased the expression of perilipins at mRNA and protein levels, also increased LDLR, SCARB1, SREBFs, and HMGCR mRNA abundance. Treatment with siNR4A1 revealed opposite results of CSNB, except for HMCGR and SREBF2. For steroidogenesis, 1 μM CSNB increased, but 50 μM CSNB inhibited P4 synthesis, NR4A1 knockdown also reduced the P4 level. Further analysis demonstrated that 1 μM CSNB increased the protein levels of StAR, HSD3B, and P-HSL, while 50 μM CSNB decreased StAR, HSD3B, and CYP11A1 protein levels. Moreover, 50 μM CSNB impaired active mitochondria, reduced the BCL2, and increased DRP1, Caspase 3, and cleaved-Caspase 3 protein levels. siNR4A1 consistently downregulated the P-HSL/HSL ratio and the steroidogenic protein levels. In conclusion, NR4A1-mediated lipid droplets are involved in the regulation of progesterone synthesis in goat luteal cells.

Radiosensitization effect of quinoline-indole-schiff base derivative 10E on non-small cell lung cancer cells in vitro and in tumor xenografts

Radioresistance is an inevitable obstacle in the clinical treatment of inoperable patients with non-small cell lung cancer (NSCLC). Combining treatment with radiosensitizers may improve the efficacy of radiotherapy. Previously, the quinoline derivative 10E as new exporter of Nur77 has shown superior antitumor activity in hepatocellular carcinoma. Here, we aimed to investigate the radiosensitizing activity and acting mechanisms of 10E. In vitro, A549 and H460 cells were treated with control, ionizing radiation (IR), 10E, and 10E + IR. Cell viability, apoptosis, and cycle were examined using CCK-8 and flow cytometry assays. Protein expression and localization were examined using western blotting and immunofluorescence. Tumor xenograft models were established to evaluate the radiosensitizing effect of 10E in vivo. 10E significantly inhibited cell proliferation and increased their radiosensitivity while reducing level of p-BCRA1, p-DNA-PKs, and 53BP1 involved in the DNA damage repair pathway, indicating that its radiosensitizing activity is closely associated with repressing DNA damage repair. A549 cells showed low level of Nur77 and a low response to IR but 10E-treated A549 cells showed high level of Nur77 indicating that Nur77 is a core radiosensitivity factor and 10E restores the expression of Nur77. Nur77 and Ku80 extranuclear co-localization in the 10E-treated A549 cells suggested that 10E-modulated Nur77 nuclear exportation inhibits DNA damage repair pathways and increases IR-triggered apoptosis. The combination of 10E and IR significantly inhibits tumor growth in a tumor xenograft model. Our findings suggest that 10E acts as a radiosensitizer and that combining 10E with radiotherapy may be a potential strategy for NSCLC treatment.

The Effect of GLUT1 and HIF-1α Expressions on Glucose Uptake and Patient Survival in Non-Small-Cell Lung Carcinoma

Lung cancer is the second-most-common cancer while being the leading cause of cancer deaths worldwide. It has been found that glucose transporter 1 (GLUT1) and hypoxia-inducible factor 1α (HIF-1α) are overexpressed in various malignancies and that they correlate with the maximum standard uptake values (SUVmax) on 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) and poor prognosis. In this study, we aim to evaluate the relationship between the SUVmax, GLUT1, and HIF-1α expression with primary tumor size, histological type, lymph node metastases, and patient survival. Of the 48 patients with non-small-cell lung cancer, those with squamous cell carcinomas (SCCs) had significantly higher GLUT1 and HIF-1α immunohistochemical expressions in comparison to adenocarcinomas (ACs), while there was no statistically significant difference in FDG accumulation between them. No significant correlation was noted between either GLUT1 or HIF-1α protein expression and FDG uptake and overall survival. However, an analysis of tumor transcriptomics showed a significant difference in overall survival depending on mRNA expression; patients with SCC and high HIF-1α levels survived longer compared to those with low HIF-1α levels, while patients with AC and low GLUT1 levels had a higher average survival time than those with high GLUT1 levels. Further studies are needed to determine the prognostic value of the expression of these factors depending on the histologic type.

Dereplication of Cytochalasans and Octaketides in Cytotoxic Extracts of Endophytic Fungi from Casearia arborea (Salicaceae)

Endophytes have been shown to be a source of novel drug prototypes. The Casearia genus is known for presenting cytotoxic clerodane diterpenes; however, there are few reports on secondary metabolites produced by its fungal microbiota. Thus, in the present study endophytic fungi obtained from the fresh leaves of C. arborea were grown in potato dextrose broth and rice to perform a secondary metabolite prospection study. The cytotoxic profile of the crude extracts at 10 µg/mL was determined by a colorimetric assay on tumor cell lines. The endophytes producing cytotoxic extracts were identified through phylogenetic analysis and belong to Diaporthe and Colletotrichum species. Metabolites present in these extracts were organized in molecular networking format based on HRMS-MS, and a dereplication process was performed to target compounds for chromatographic purification. Metabolic classes, such as lipids, peptides, alkaloids, and polyketides were annotated, and octaketide and cytochalasin derivatives were investigated. Cytochalasin H was purified from the cytotoxic Diaporthe sp. CarGL8 extract and its cytotoxic activity was determined on human cancer cell lines A549, MCF-7, and HepG2. The data collected in the present study showed that molecular networking is useful to understand the chemical profile of complex matrices to target compounds, minimizing the cost and time spent in purification processes.

Therapeutic potential of NR4A1 in cancer: Focus on metabolism

Metabolic reprogramming is a vital hallmark of cancer, and it provides the necessary energy and biological materials to support the continuous proliferation and survival of tumor cells. NR4A1 is belonging to nuclear subfamily 4 (NR4A) receptors. NR4A1 plays diverse roles in many tumors, including melanoma, colorectal cancer, breast cancer, and hepatocellular cancer, to regulate cell growth, apoptosis, metastasis. Recent reports shown that NR4A1 exhibits unique metabolic regulating effects in cancers. This receptor was first found to mediate glycolysis via key enzymes glucose transporters (GLUTs), hexokinase 2 (HK2), fructose phosphate kinase (PFK), and pyruvate kinase (PK). Then its functions extended to fatty acid synthesis by modulating CD36, fatty acid-binding proteins (FABPs), sterol regulatory element-binding protein 1 (SREBP1), glutamine by Myc, mammalian target of rapamycin (mTOR), and hypoxia-inducible factors alpha (HIF-1α), respectively. In addition, NR4A1 is involving in amino acid metabolism and tumor immunity by metabolic processes. More and more NR4A1 ligands are found to participate in tumor metabolic reprogramming, suggesting that regulating NR4A1 by novel ligands is a promising approach to alter metabolism signaling pathways in cancer therapy. Basic on this, this review highlighted the diverse metabolic roles of NR4A1 in cancers, which provides vital references for the clinical application.

Cytosporone B (Csn-B), an NR4A1 agonist, attenuates acute cardiac allograft rejection by inducing differential apoptosis of CD4+T cells

CD4+T cell-mediated acute rejection remains a major factor that affects the early survival of transplanted organs post-transplantation. Here, we reveal that nuclear receptor subfamily 4 Group A member 1 (Nr4A1) was upregulated during cardiac allograft rejection and that the increased Nr4A1 was primarily localized in intragraft-infiltrating CD4+T cells. Nr4A1 acts as a transcription factor with an important role in CD4+T cell apoptosis, differentiation and T cell dysfunction, which indicates that Nr4A1 may play a critical role in transplant rejection. Cytosporone B (Csn-B) is a naturally occurring agonist of Nr4A1, and the role of Csn-B in the physiological process of cardiac rejection is poorly defined. This study constructed an acute rejection model of abdominal heterotopic cardiac transplantation in mice and investigated whether Csn-B could attenuate acute transplant rejection by modulating the CD4+T lymphocyte response. The results showed that Csn-B prolonged murine cardiac allograft survival and reduced inflammation in allografts. Subsequently, it was confirmed that Csn-B functions by inducing non-Treg apoptosis and promoting Treg cell differentiation. Finally, we also confirmed that Csn-B attenuates acute rejection by directly targeting Nr4A1 in CD4+T cells. Our data suggest that Csn-B is a promising novel therapeutic approach for acute cardiac allograft rejection.

Discovery of new chiral sulfonamides bearing benzoxadiazole as HIF inhibitors for non-small cell lung cancer therapy: design, microwave-assisted synthesis, binding affinity, in vitro antitumoral activities and in silico studies

Thirty-four chiral compounds having benzoxadiazole and sulfonamide moieties on the skeleton have been synthesized. The in vitro cytotoxic activity and apoptotic effects of these compounds have been evaluated using the A549 lung cancer cell line.

Knockdown of lncRNA HIF1A-AS2 increases drug sensitivity of SCLC cells in association with autophagy

The aim of this study was to determine the effect of lncRNA HIF1A-AS2 on autophagy-associated drug resistance in small cell lung cancer (SCLC) cells. The expression of HIF1A-AS2 was silenced by siRNA in doxorubicin-sensitive H69 and doxorubicin-resistant H69AR cells. Then, cytotoxicity, apoptosis and autophagy analyses were carried out in the normoxic and CoCl₂-induced hypoxic environment. The effect of HIF1A-AS2 on the expression levels of genes, which are associated with drug resistance and autophagy, was determinated by qRT-PCR analysis. The levels of MRP1, HIF-1α and Beclin-1 were analyzed by western blot method. Knockdown of HIF1A-AS2 increased doxorubicin sensitivity of SCLC cells and decreased autophagy. Knockdown of HIF1A-AS2 has also affected the expression of several genes that will increase drug sensitivity and inhibit autophagy in both cell lines. The levels of HIF-1α and Beclin-1 were decreased in both cell lines by knockdown of HIF1A-AS2. MRP1 expression was decrease in H69AR cells. In addition, CoCl₂-induced hypoxic environment decreased in doxorubicin sensitivity of H69 cells, and knockdown of HIF1A-AS2 reversed this effect of hypoxia. Knockdown of HIF1A-AS2 increased drug sensitivity of SCLC cells in relation to autophagy. Therefore, hypoxia-HIF1A-AS2-autophagy interaction is thought to be determinative in drug sensitivity of these cells.

Malayoside, a cardenolide glycoside extracted from Antiaris toxicaria Lesch, induces apoptosis in human non-small lung cancer cells via MAPK-Nur77 signaling pathway

Lung cancer is the leading cause of cancer deaths in the world. Non-small cell lung cancer (NSCLC), with poor prognosis and resistance to chemoradiotherapy, is the most common histological type of lung cancer. Therefore, it is necessary to develop new and more effective treatment strategy for NSCLC. Nur77, an orphan member of the nuclear receptor superfamily, induces apoptosis in cancer cells including NSCLC cells, by high expression and translocation to mitochondria. Small molecules trigger expression and mitochondrial localization of Nur77 may be an ideal anti-cancer drug candidate. Here, we report malayoside, a cardiac glycoside in the extract of Antiaris toxicaria Lesch., had different sensitivities to NSCLC cells. Malayoside induced apoptosis in NCI-H460 cells. Meanwhile, malayoside induced Nur77 expression and mitochondrial localization, and its induction of apoptosis was Nur77-dependent. To investigate the molecular mechanism of malayoside inducing Nur77 and apoptosis, we found that malayoside activated MAPK signaling pathway, including both ERK and p38 phosphorylation. The suppression of MAPK signaling activation inhibited the expression of Nur77 and apoptosis induced by malayoside. Our studies in nude mice showed that malayside potently inhibited the growth of tumor cells in vivo. Furthermore, the anti-cancer effect of malayosidwas in vivo was also related to the elevated expression of Nur77, p-ERK, and p-p38 proteins. Our results suggest that malayoside possesses an anti-NSCLC activity in vitro and in vivo mainly via activation of MAPK-Nur77 signaling pathway, indicating that malayoside is a promising chemotherapeutic candidate for NSCLC.

The Paradoxical Roles of Orphan Nuclear Receptor 4A (NR4A) in Cancer

The three-orphan nuclear receptor 4A genes are induced by diverse stressors and stimuli, and there is increasing evidence that NR4A1 (Nur77), NR4A2 (Nurr1), and NR4A3 (Nor1) play an important role in maintaining cellular homeostasis and in pathophysiology. In blood-derived tumors (leukemias and lymphomas), NR4A expression is low and NR4A1-/-/NR4A3-/- double knockout mice rapidly develop acute myelocytic leukemia, suggesting that these receptors exhibit tumor suppressor activity. Treatment of leukemia and most lymphoma cells with drugs that induce expression of NR4A1and NR4A3 enhances apoptosis, and this represents a potential clinical application for treating this disease. In contrast, most solid tumor-derived cell lines express high levels of NR4A1 and NR4A2, and both receptors exhibit pro-oncogenic activities in solid tumors, whereas NR4A3 exhibits tumor-specific activities. Initial studies with retinoids and apoptosis-inducing agents demonstrated that their cytotoxic activity is NR4A1 dependent and involved drug-induced nuclear export of NR4A1 and formation of a mitochondrial proapoptotic NR4A1-bcl-2 complex. Drug-induced nuclear export of NR4A1 has been reported for many agents/biologics and involves interactions with multiple mitochondrial and extramitochondrial factors to induce apoptosis. Synthetic ligands for NR4A1, NR4A2, and NR4A3 have been identified, and among these compounds, bis-indole derived (CDIM) NR4A1 ligands primarily act on nuclear NR4A1 to inhibit NR4A1-regulated pro-oncogenic pathways/genes and similar results have been observed for CDIMs that bind NR4A2. Based on results of laboratory animal studies development of NR4A inducers (blood-derived cancers) and NR4A1/NR4A2 antagonists (solid tumors) may be promising for cancer therapy and also for enhancing immune surveillance.

Jiedu Sangen decoction inhibits chemoresistance to 5-fluorouracil of colorectal cancer cells by suppressing glycolysis via PI3K/AKT/HIF-1α signaling pathway

Drug resistance is a major obstacle in the development of effective colorectal cancer (CRC) therapy. Our study aimed to explore the reversal abilities of Jiedu Sangen decoction (JSD) on the 5-fluorouracil (5-FU) resistance and its underlying molecular mechanisms. Expression changes in HIF-1 of CRC tissues were firstly revealed by bioinformatics analysis. Afterwards, cell viabilities of JSD and 5-FU treatments on 5-FU resistant human colon cancer cells (HCT-8/5-FU) were determined. Expressions of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT)/p-AKT, hypoxia-inducible factor 1 (HIF-1α), as well as glycolysis related proteins such as L-lactate dehydrogenase A (LDHA), Glucose transporter type 1 (Glut1), Hexokinase 2 (HKII), and cysteinyl aspartate specific proteinase (Caspase) family members in HCT-8/5-FU cells, HIF-1α silenced HCT-8/5-FU cells and tumor tissues were detected by western blotting. HIF-1α was found over expressed in CRC tissues according to public available datasets in Oncomine. Growth inhibition rates of HCT-8/5-FU cells were increased along with the increase of JSD concentrations. JSD caused down-regulated HIF-1α, PI3K, AKT/p-AKT, HKII and Glut1, as well as up-regulated Caspase3 and Caspase9 in HCT-8/5-FU cells and tumor tissues. In HIF-1α silenced HCT-8/5-FU cells, synergistic group showed significantly reduced expression levels of PI3K, AKT, p-AKT. Additionally, up-regulated expressions of Caspase6 and Caspase7 were observed. JSD combined with 5-FU also exhibited obvious inhibitory efficiency on tumor growth in vivo. JSD may reverse 5-FU resistance by suppressing glycolysis via PI3K/AKT/HIF-1α signaling pathway, thereby inhibiting glycolysis and induce apoptosis to enhance anti-tumor activity.

Pretreatment to Posttreatment Hypoxia Inducible Factor-1α Ratios as a Potentially Predictive Marker for First-Line Treatment in Nonsmall Cell Lung Cancer Patients without Known Driver Mutations

Background: Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) are key angiogenic regulatory factors. The aim of this study was to identify the most useful prognostic angiogenic factors in advanced nonsmall cell lung cancer (NSCLC) without known driver gene mutations. Methods: Eligible patients were pathologically confirmed to have advanced NSCLC without known driver mutations. All patients were treated with standard first-line chemotherapy ± bevacizumab. Serum concentrations of HIF-1α, VEGF, sVEGFR1, sVEGFR2, and endostatin were measured via enzyme-linked immunosorbent assays (ELISAs) prior to and after two cycles of treatment. Area under the curve (AUC) and optimal cutoff values were calculated by receiver operator characteristic curve (ROC) analyses. The parameters that predicted survival were evaluated by univariate and multivariate Cox proportional hazard analyses. Results: A total of 47 patients were included in this study. HIF-1α levels decreased significantly after treatment in the nonprogressing (partial response/stable disease) patient group (707.94 vs. 355.53 pg/mL, p = 0.002), but increased levels were seen in patients with progressive disease, however, the extent of change did not reach significance (173.70 vs. 416.34 pg/mL, p = 0.078). An HIF-1α ratio of 1.18 was chosen as the best point to predict treatment response through ROC analyses. Via univariate and multivariate analyses, we found that patients with a HIF-1α ratio ≥1.18 after treatment were significantly more likely to have a prolonged progression-free survival (PFS, HR 0.303, 95% CI: 0.153-0.603, p = 0.001) and overall survival (OS, HR 0.436, 95% CI: 0.153-0.603, p = 0.025). Conclusions: We identified the pretreatment to posttreatment HIF-1α ratio as a promising predictor for PFS and OS in NSCLC patients without known driver mutations.

Hyperoside suppresses hypoxia-induced A549 survival and proliferation through ferrous accumulation via AMPK/HO-1 axis

BACKGROUND

Hypoxia is commonly existed in tumors and lead to cancer cell chemo/radio-resistance. It is well-recognized that tumor hypoxia is a major challenge for the treatment of various solid tumors. Hyperoside (quercetin-3-O-galactoside, Hy) possesses antioxidant effects and has been reported to protect against hypoxia/reoxygenation induced injury in cardiomyocytes. Therefore, Hy may be attractive compound applicable to hypoxia-related diseases.

PURPOSE

This study was designed to determine the role of Hy in hypoxia-induced proliferation of non-small cell lung cancer cells and the underlying mechanism.

STUDY DESIGN AND METHODS

A549, a human non-small cell lung cancer (NSCLC) cell line, was used in the present study. 1% O₂ was used to mimic the in vivo hypoxic condition of NSCLC. The potential mechanisms of Hy on hypoxia-induced A549 survival and proliferation, as well as the involvement of AMPK/HO-1 pathway were studied via CCK-8 assay, EdU staining, flow cytometry, qRT-PCR and western blot.

RESULTS

We showed that pretreatment with Hy suppressed hypoxia-induced A549 survival and proliferation in dose-dependent manner. In terms of mechanism, hypoxia-treated A549 showed the lower AMPK phosphorylation and the reduced HO-1 expression, which were reversed by Hy pretreatment. Both AMPK inhibitor (Compound C) and HO-1 activity inhibitor (Zinc protoporphyrin IX) abolished Hy-evoked A549 cell death under hypoxia stimuli. Of note, Ferrous iron contributed to Hy-induced A549 cell death under hypoxia, while Hy had no effect on lipid peroxidation under hypoxia.

CONCLUSION

Taken together, our results highlighted the beneficial role of Hy against hypoxia-induced A549 survival and proliferation through ferrous accumulation via AMPK/HO-1 axis.

HIF-1α Levels in patients receiving chemoradiotherapy for locally advanced non-small cell lung carcinoma

AIM

To examine the relationship between treatment response and hypoxia-inducible factor-1 alpha (HIF-1α) levels in patients with locally advanced non-small cell lung cancer (NSCLC) who received chemoradiotherapy (CRT).

METHODS

Eighty patients with NSCLC were included in the study and treated at Acibadem Mehmet Ali Aydınlar University Medical Faculty. HIF-1 α levels were measured before and after CRT by the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

Patients' stages were as follows; stage IIIA (65%) and stage IIIB (35%). Squamous histology was 45%, adenocarcinoma was 44%, and others were 11%. Chemotherapy and radiotherapy were given concurrently to 80 patients. Forty-five (56%) patients received cisplatin-based chemotherapy, and 35 (44%) received carboplatin-based chemotherapy. Serum HIF-1α levels (42.90 ± 10.55 pg/mL) after CRT were significantly lower than the pretreatment levels (63.10 ± 10.22 pg/mL, p<0.001) in patients with locally advanced NSCLC.

CONCLUSION

The results of this study revealed that serum HIF-1α levels decreased after CRT. Decrease of HIF-1α levels after the initiation of CRT may be useful for predicting the efficacy of CRT.

DNA Methylation Changes in Regional Lung Macrophages Are Associated with Metabolic Differences

A number of pulmonary diseases occur with upper lobe predominance, including cystic fibrosis and smoking-related chronic obstructive pulmonary disease. In the healthy lung, several physiologic and metabolic factors exhibit disparity when comparing the upper lobe of the lung to lower lobe, including differences in oxygenation, ventilation, lymphatic flow, pH, and blood flow. In this study, we asked whether these regional differences in the lung are associated with DNA methylation changes in lung macrophages that could potentially lead to altered cell responsiveness upon subsequent environmental challenge. All analyses were performed using primary lung macrophages collected via bronchoalveolar lavage from healthy human subjects with normal pulmonary function. Epigenome-wide DNA methylation was examined via Infinium MethylationEPIC (850K) array and validated by targeted next-generation bisulfite sequencing. We observed 95 CpG loci with significant differential methylation in lung macrophages, comparing upper lobe to lower lobe (all false discovery rate < 0.05). Several of these genes, including CLIP4, HSH2D, NR4A1, SNX10, and TYK2, have been implicated as participants in inflammatory/immune-related biological processes. Functionally, we identified phenotypic differences in oxygen use, comparing upper versus lower lung macrophages. Our results support a hypothesis that epigenetic changes, specifically DNA methylation, at a multitude of gene loci in lung macrophages are associated with metabolic differences regionally in lung.

Characteristics of Nur77 and its ligands as potential anticancer compounds (Review)

Nuclear receptor subfamily 4 group A member 1 (NR4A1; also termed Nur77/TR3/NGFIB), a member of the nuclear receptor superfamily, is expressed as an early response gene to regulate the expression of multiple target genes. Nur77 has the typical structure of a nuclear receptor, including an N‑terminal domain, a DNA binding domain, and a ligand‑binding domain. The expression and localization of Nur77 are closely associated with its roles in cell proliferation and apoptosis. Nur77 was first identified as an orphan receptor, the endogenous ligand of which has not yet been identified; however, an increasing number of compounds targeting Nur77 have been reported to have beneficial effects in the treatment of cancer and other diseases. This review provides a brief overview of the identification, structure, expression and localization, transcriptional role and non‑genomic function of Nur77, and summarizes the ligands that have been shown to interact with Nur77, including cytosporone B, cisplatin, TMPA, PDNPA, CCE9, THPN, Z‑ligustilide, celastrol and bisindole methane compounds, which may potentially be used to treat cancer in humans.

MiR-429 improved the hypoxia tolerance of human amniotic cells by targeting HIF-1α

MicroRNA-429(miR-429) plays an important role in mesenchymal stem cells. Hypoxia-inducible factor 1α (HIF-1α) is a nuclear transcription factor that regulates the proliferation, apoptosis and tolerance to hypoxia of mesenchymal stem cells. HIF-1α is also a target gene of miR-429. We investigated whether miR-429 plays a role in hypoxia tolerance with HIF-1α in human amniotic mesenchymal stem cells (hAMSCs). The expression of miR-429 was increased by hypoxia in hAMSCs. miR-429 expression resulted in decreased HIF-1α protein level, but little effect on HIF-1α mRNA. While overexpression of HIF-1α increased the survival rate and exhibited anti-apoptosis effects in hAMSCs under hypoxia, co-expression of miR-429 reduced survival and increased apoptosis. However, miR-429 silencing with HIF-1α overexpression stimulated cell survival and reduced apoptosis. Co-expression of HIF-1α and miR-429 reduced VEGF and Bcl-2 proteins and increased Bax and C-Caspase-3 levels in hAMSCs under hypoxia compared with cells expressing only HIF-1α; cells with HIF-1α overexpression and miR-429 silencing showed the opposite effects. These results indicate that HIF-1α and angomiR-429 reciprocally antagonized each other, while HIF-1α and antagomiR-429 interacted with each other to regulate survival and apoptosis in hAMSCs under hypoxia. miR-429 increased VEGF and Bcl-2 protein levels and decreased Bax and cleaved Caspase-3 protein levels by promoting the synthesis of HIF-1α. These results indicate that miR-429 negatively regulates the survival and anti-apoptosis ability of hAMSCs by mediating HIF-1α expression and improves the ability of hAMSCs to tolerate hypoxia.