The transcription factor Egr1 is a direct regulator of multiple tumor suppressors including TGFbeta1, PTEN, p53, and fibronectin

Leptin is a direct transcriptional target of EGR1 in human breast cancer cells

Leptin is a cytokine that regulates energy metabolism. Leptin can promote breast cancer progression in obese women. However, the mechanism of regulation of leptin expression in breast cancer cells is unclear. Tumor necrosis factor-alpha (TNF-α) stimulated the transcription of the leptin gene. Using mutant promoter constructs, we demonstrated that the EGR1-binding motif in the proximal region of the leptin gene is required for leptin transcription by TNF-α. Forced expression of EGR1 stimulated leptin promoter activity, whereas silencing of EGR1 by RNA interference reduced TNF-α-induced leptin protein accumulation. The ERK1/2 pathway contributed to the expression of EGR1 and leptin by TNF-α. Our results suggest that EGR1 targets the leptin gene in response to TNF-α stimulation in breast cancer cells.

Tumor suppression by the EGR1, DMP1, ARF, p53, and PTEN Network

Recent studies have indicated that EGR1 is a direct regulator of tumor suppressors including TGFβ1, PTEN, and p53. The Myb-like transcription factor Dmp1 is a physiological regulator of the Arf-p53 pathway through transactivation of the Arf promoter and physical interaction of p53. The Dmp1 promoter has binding sites for Egr proteins, and Egr1 is a target for Dmp1. Crosstalks between p53 and PTEN have been reported. The Egr1-Dmp1-Arf-p53-Pten pathway displays multiple modes of interaction with each other, suggesting the existence of a functional network of tumor suppressors that maintain normal cell growth and prevent the emergence of incipient cancer cells.

Chromatin accessibility prediction via a hybrid deep convolutional neural network

Motivation

A majority of known genetic variants associated with human-inherited diseases lie in non-coding regions that lack adequate interpretation, making it indispensable to systematically discover functional sites at the whole genome level and precisely decipher their implications in a comprehensive manner. Although computational approaches have been complementing high-throughput biological experiments towards the annotation of the human genome, it still remains a big challenge to accurately annotate regulatory elements in the context of a specific cell type via automatic learning of the DNA sequence code from large-scale sequencing data. Indeed, the development of an accurate and interpretable model to learn the DNA sequence signature and further enable the identification of causative genetic variants has become essential in both genomic and genetic studies.

Results

We proposed Deopen, a hybrid framework mainly based on a deep convolutional neural network, to automatically learn the regulatory code of DNA sequences and predict chromatin accessibility. In a series of comparison with existing methods, we show the superior performance of our model in not only the classification of accessible regions against background sequences sampled at random, but also the regression of DNase-seq signals. Besides, we further visualize the convolutional kernels and show the match of identified sequence signatures and known motifs. We finally demonstrate the sensitivity of our model in finding causative noncoding variants in the analysis of a breast cancer dataset. We expect to see wide applications of Deopen with either public or in-house chromatin accessibility data in the annotation of the human genome and the identification of non-coding variants associated with diseases.

Availability and implementation

Deopen is freely available at https://github.com/kimmo1019/Deopen.

Supplementary information

Supplementary data are available at Bioinformatics online.

Early Growth Response Gene-1 Suppresses Foot-and-Mouth Disease Virus Replication by Enhancing Type I Interferon Pathway Signal Transduction

Early growth response gene-1 (EGR1) is a multifunctional transcription factor that is implicated in viral infection. In this study, we observed that foot-and-mouth disease virus (FMDV) infection significantly triggered EGR1 expression. Overexpression of EGR1 suppressed FMDV replication in porcine cells, and knockdown of EGR1 considerably promoted FMDV replication. A previously reported FMDV mutant virus (with two amino acids mutations in SAP domain) that displays a strong type I interferon (IFN) induction activity was used in this study. We found that SAP mutant FMDV infection induced a higher expression of EGR1 than wildtype FMDV infection, and also triggered higher IFN-β and IFN-stimulated genes (ISGs) expression than wildtype FMDV infection. This implied a link between EGR1 and type I IFN signaling. Further study showed that overexpression of EGR1 resulted in Sendai virus (SeV)-induced IFN-stimulated response element (ISRE) and NF-κB promoter activation. In addition, the SeV-induced ISGs expression was impaired in EGR1 knockdown cells. EGR1 upregulation promoted type I IFN signaling activation and suppressed FMDV and Seneca Valley virus replication. Suppression of the transcriptional activity of EGR1 did not affect its antiviral effect against FMDV. This study reveals a new mechanism evolved by EGR1 to enhance type I IFN signaling and suppress FMDV replication.

Daphnane diterpenes inhibit the metastatic potential of B16F10 murine melanoma cells in vitro and in vivo

BACKGROUND

Melanoma is one of the most invasive and aggressive types of cancer with a very poor prognosis. Surgery remains the most efficient treatment prior melanoma invasion and metastasis formation. However, therapy becomes a challenge once the cancer cells colonized other tissues. At present, there are two main classes of therapies acting with a certain efficiency on metastatic melanoma: immune check point inhibitors (anti-PD1/PDL1) and targeted therapy such as Vemurafenib. Unfortunately, these therapies are not fully responsive, induce resistance and/or generate unwanted side effects. In this respect, it is important to continue to discover new cancer therapeutics. Here, we show that daphnane diterpenes type of compounds can prevent melanoma metastasis by inhibiting metastasis-associated matrix metalloproteinases expression without cytotoxicity.

METHODS

Evaluation of the anti-metastasis effect of daphnane diterpenes-rich Thymelaea hirsuta extract (TH) and its bioactive component gnidilatidin was carried out in vitro using B16 murine melanoma cells and in vivo using male C57BL/6 J mice. Global gene expression in B16 cells was done using DNA microarray, validated using real-time PCR, to further understand the effect of daphnane diterpenes, specifically daphnane diterpenoid gnidilatidin.

RESULTS

Oral administration of daphnane diterpenes-rich Thymelaea hirsuta extract (TH) suppressed MMP2 and MMP9 expression, decreasing lung tumor in mice injected with B16 murine melanoma cells. Validation of these observations in vitro showed reduced B16 cells migration, adhesion, and invasion. Results of microarray analysis of B16 cells treated with daphnane diterpenoid gnidilatidin from TH revealed an upregulation of tumor suppressor Egr1 while inhibiting metastasis-associated genes Id2 and Sytl2 expression. A downregulation of the melanoma oncogene microphthalmia-associated transcription factor (Mitf) was observed, and most likely caused by the inhibition of Id2, a gene that regulated HLH transcription factors such as MITF and also reported to promote tumor cell migration and invasion.

CONCLUSIONS

Daphnane diterpenes have inhibitory effect on the metastatic potential of B16 melanoma cells, and the results of this study provided evidence for their potential for use in the prevention and inhibition of melanoma metastasis.

Analysis of Transcription Factor-Related Regulatory Networks Based on Bioinformatics Analysis and Validation in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for a significant proportion of liver cancer, which has become the second most common cause of cancer-related mortality worldwide. To investigate the potential mechanisms of invasion and progression of HCC, bioinformatics analysis and validation by qRT-PCR were performed. We found 237 differentially expressed genes (DEGs) including EGR1, FOS, and FOSB, which were three cancer-related transcription factors. Subsequently, we constructed TF-gene network and miRNA-TF-mRNA network based on data obtained from mRNA and miRNA expression profiles for analysis of HCC. We found that 42 key genes from the TF-gene network including EGR1, FOS, and FOSB were most enriched in the p53 signaling pathway. The qRT-PCR data confirmed that mRNA levels of EGR1, FOS, and FOSB all were decreased in HCC tissues. In addition, we confirmed that the mRNA levels of CCNB1, CCNB2, and CHEK1, three key markers of the p53 signaling pathway, were all increased in HCC tissues by bioinformatics analysis and qRT-PCR validation. Therefore, we speculated that miR-181a-5p, which was upregulated in HCC tissues, could regulate FOS and EGR1 to promote the invasion and progression of HCC by p53 signaling pathway. Overall, the study provides support for the possible mechanisms of progression in HCC.

Establishing normal metabolism and differentiation in hepatocellular carcinoma cells by culturing in adult human serum

Tissue culture medium routinely contains fetal bovine serum (FBS). Here we show that culturing human hepatoma cells in their native, adult serum (human serum, HS) results in the restoration of key morphological and metabolic features of normal liver cells. When moved to HS, these cells show differential transcription of 22–32% of the genes, stop proliferating, and assume a hepatocyte-like morphology. Metabolic analysis shows that the Warburg-like metabolic profile, typical for FBS-cultured cells, is replaced by a diverse metabolic profile consistent with in vivo hepatocytes, including the formation of large lipid and glycogen stores, increased glycogenesis, increased beta-oxidation and ketogenesis, and decreased glycolysis. Finally, organ-specific functions are restored, including xenobiotics degradation and secretion of bile, VLDL and albumin. Thus, organ-specific functions are not necessarily lost in cell cultures, but might be merely suppressed in FBS. The effect of serum is often overseen in cell culture and we provide a detailed study in the changes that occur and provide insight in some of the serum components that may play a role in the establishment of the differentiated phenotype.

Estrogen-induced transcription factor EGR1 regulates c-Kit transcription in the mouse uterus to maintain uterine receptivity for embryo implantation

Early growth response 1 (Egr1) is a key transcription factor that mediates the action of estrogen (E₂) to establish uterine receptivity for embryo implantation. However, few direct target genes of EGR1 have been identified in the uterus. Here, we demonstrated that E₂ induced EGR1-regulated transcription of c-Kit, which plays a crucial role in cell fate decisions. Spatiotemporal expression of c-Kit followed that of EGR1 in uteri of ovariectomized mice at various time points after E₂ treatment. E₂ activated ERK1/2 and p38 to induce EGR1, which then activated c-Kit expression in the uterus. EGR1 transfection produced rapid and transient induction of c-KIT in a time- and dose-dependent manner. Furthermore, luciferase assays to measure c-Kit promoter activity confirmed that a functional EGR1 binding site(s) (EBS) was located within -1 kb of the c-Kit promoter. Site-directed mutagenesis and chromatin immunoprecipitation-PCR for three putative EBS within -1 kb demonstrated that the EBS at -818/-805 was critical for EGR1-dependent c-Kit transcription. c-Kit expression was significantly increased in the uterus on day 4 and administration of Masitinib, a c-Kit inhibitor, effectively interfered with embryo implantation. Collectively, our results showed that estrogen induces transcription factor EGR1 to regulate c-Kit transcription for uterine receptivity for embryo implantation in the mouse uterus.

Effects of the combination of As2O3 and AZT on proliferation inhibition and apoptosis induction of hepatoma HepG2 cells following silencing of Egr-1

Context

Previous studies have demonstrated that 3′-azido-3′-deoxythymidine (AZT) and arsenic trioxide (As₂O₃), traditional chemotherapy agents, can synergically inhibit the growth of hepatocellular carcinoma cells. However, the molecular mechanisms underlying As₂O₃ and AZT anti-hepatoma activity are unknown.

Objective

This study aimed to investigate the role of early growth response protein 1 (Egr-1) in the process of As₂O₃ combined with AZT inhibiting proliferation and inducing apoptosis of human hepatocellular carcinoma HepG2 cells, and explore the possible mechanism.

Materials and methods

The expression of Egr-1 was silenced using siRNA, and then HepG2 cells were treated with As₂O₃ (2 μM) and AZT (20 μM). The rates of cell inhibition and apoptosis were determined by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) method and flow cytometry, respectively. The mRNA and protein expression of p53, caspase-3, and Egr-1 were detected by real-time quantitative polymerase chain reaction and Western blotting, respectively.

Results

The inhibitory rate of As₂O₃ (2 μM) combined with AZT (20 μM) on proliferation of HepG2 cells was significantly higher than that of As₂O₃ alone. The combination index (CI) values were 0.2<CI<0.4, showing strong synergic effect. After silencing Egr-1, the proliferation inhibition and proapoptotic ability of As₂O₃ combined with AZT on HepG2 cells were decreased, and the CI value was greater than 1, showing antagonistic effect. In addition, the expression of p53 and caspase-3 mRNA/protein was also significantly decreased.

Conclusion

The present results show that AZT could increase the sensitization of As₂O₃ for inhibiting proliferation and promoting apoptosis of HepG2 cells through regulating the expression of Egr-1, which may control the expression of p53 and caspase-3.

Lead Neurotoxicity on Human Neuroblastoma Cell Line SH-SY5Y is Mediated via Transcription Factor EGR1/Zif268 Induced Disrupted in Scherophernia-1 Activation

Lead (Pb²⁺) is a well-known type of neurotoxin and chronic exposure to Pb²⁺ induces cognition dysfunction. In this work, the potential role of early growth response gene 1 (EGR1) in the linkage of Pb²⁺ exposure and disrupted in scherophernia-1 (DISC1) activity was investigated. Human neuroblastoma cell line SH-SY5Y was subjected to different concentrations of lead acetate (PbAc) to determine the effect of Pb²⁺ exposure on the cell viability, apoptosis, and activity of EGR1 and DISC1. Then the expression of EGR1 in SH-SY5Y cells was knocked down with specific siRNA to assess the function of EGR1 in Pb²⁺ induced activation of DISC1. The interaction between EGR1 and DISC1 was further validated with dual luciferase assay, Supershift electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP)-PCR. Administration of PbAc decreased cell viability and induced apoptosis in SH-SY5Y cells in a dose-dependent manner. Additionally, exposure to PbAc also up-regulated expression of EGR1 and DISC1 at all concentrations. Knockdown of EGR1 blocked the effect of PbAc on SH-SY5Y cells, indicating the central role of EGR1 in the function of Pb²⁺ on activity of DISC1. Based on the results of dual luciferase assay, Supershift EMSA, and ChIP-PCR, EGR1 mediated the effect of Pb²⁺ on DISC1 by directly bound to the promoter region of DISC1 gene. The current study elaborated the mechanism involved in the effect of Pb²⁺ exposure on expression of DISC1 for the first time: EGR1 activated by Pb²⁺ substitution of zinc triggered the transcription of DISC1 gene by directly binding to its promoter.

Lipoxins Regulate the Early Growth Response-1 Network and Reverse Diabetic Kidney Disease

Background The failure of spontaneous resolution underlies chronic inflammatory conditions, including microvascular complications of diabetes such as diabetic kidney disease. The identification of endogenously generated molecules that promote the physiologic resolution of inflammation suggests that these bioactions may have therapeutic potential in the context of chronic inflammation. Lipoxins (LXs) are lipid mediators that promote the resolution of inflammation.Methods We investigated the potential of LXA₄ and a synthetic LX analog (Benzo-LXA₄) as therapeutics in a murine model of diabetic kidney disease, ApoE^-/- mice treated with streptozotocin.Results Intraperitoneal injection of LXs attenuated the development of diabetes-induced albuminuria, mesangial expansion, and collagen deposition. Notably, LXs administered 10 weeks after disease onset also attenuated established kidney disease, with evidence of preserved kidney function. Kidney transcriptome profiling defined a diabetic signature (725 genes; false discovery rate P≤0.05). Comparison of this murine gene signature with that of human diabetic kidney disease identified shared renal proinflammatory/profibrotic signals (TNF-α, IL-1β, NF-κB). In diabetic mice, we identified 20 and 51 transcripts regulated by LXA₄ and Benzo-LXA₄, respectively, and pathway analysis identified established (TGF-β1, PDGF, TNF-α, NF-κB) and novel (early growth response-1 [EGR-1]) networks activated in diabetes and regulated by LXs. In cultured human renal epithelial cells, treatment with LXs attenuated TNF-α-driven Egr-1 activation, and Egr-1 depletion prevented cellular responses to TGF-β1 and TNF-αConclusions These data demonstrate that LXs can reverse established diabetic complications and support a therapeutic paradigm to promote the resolution of inflammation.

EGR1 mediates miR-203a suppress the hepatocellular carcinoma cells progression by targeting HOXD3 through EGFR signaling pathway

EGR1 plays a critical role in cancer progression. However, its precise role in hepatocellular carcinoma has not been elucidated. In this study, we found that the overexpression of EGR1 suppresses hepatocellular carcinoma cell proliferation and increases cell apoptosis by binding to the miR-203a promoter sequence. In addition, we investigated the function of miR-203a on progression of HCC cells. We verified that the effect of overexpression of miR-203a is consistent with that of EGR1 in regulation of cell progression. Through bioinformatic analysis and luciferase assays, we confirmed that miR-203a targets HOXD3. Silencing HOXD3 could block transition of the G2/M phase, increase cell apoptosis, decrease the expression of cell cycle and apoptosis-related proteins, EGFR, p-AKT, p-ERK, CCNB1, CDK1 and Bcl2 by targeting EGFR through EGFR/AKT and ERK cell signaling pathways. Likewise, restoration of HOXD3 counteracted the effects of miR-203a expression.In conclusion, our findings are the first to demonstrate that EGR1 is a key player in the transcriptional control of miR-203a, and that miR-203a acts as an anti-oncogene to suppress HCC tumorigenesis by targeting HOXD3 through EGFR-related cell signaling pathways.

Molecular targets and signaling pathways regulated by nuclear translocation of syndecan-1

Background

The cell-surface heparan sulfate proteoglycan syndecan-1 is important for tumor cell proliferation, migration, and cell cycle regulation in a broad spectrum of malignancies. Syndecan-1, however, also translocates to the cell nucleus, where it might regulate various molecular functions.

Results

We used a fibrosarcoma model to dissect the functions of syndecan-1 related to the nucleus and separate them from functions related to the cell-surface. Nuclear translocation of syndecan-1 hampered the proliferation of fibrosarcoma cells compared to the mutant lacking nuclear localization signal. The growth inhibitory effect of nuclear syndecan-1 was accompanied by significant accumulation of cells in the G0/G1 phase, which indicated a possible G1/S phase arrest.

We implemented multiple, unsupervised global transcriptome and proteome profiling approaches and combined them with functional assays to disclose the molecular mechanisms that governed nuclear translocation and its related functions. We identified genes and pathways related to the nuclear compartment with network enrichment analysis of the transcriptome and proteome. The TGF-β pathway was activated by nuclear syndecan-1, and three genes were significantly altered with the deletion of nuclear localization signal: EGR-1 (early growth response 1), NEK11 (never-in-mitosis gene a-related kinase 11), and DOCK8 (dedicator of cytokinesis 8). These candidate genes were coupled to growth and cell-cycle regulation. Nuclear translocation of syndecan-1 influenced the activity of several other transcription factors, including E2F, NFκβ, and OCT-1. The transcripts and proteins affected by syndecan-1 showed a striking overlap in their corresponding biological processes. These processes were dominated by protein phosphorylation and post-translation modifications, indicative of alterations in intracellular signaling. In addition, we identified molecules involved in the known functions of syndecan-1, including extracellular matrix organization and transmembrane transport.

Conclusion

Collectively, abrogation of nuclear translocation of syndecan-1 resulted in a set of changes clustering in distinct patterns, which highlighted the functional importance of nuclear syndecan-1 in hampering cell proliferation and the cell cycle. This study emphasizes the importance of the localization of syndecan-1 when considering its effects on tumor cell fate.

Electronic supplementary material

The online version of this article (10.1186/s12860-017-0150-z) contains supplementary material, which is available to authorized users.

Transcriptional regulation of CacyBP/SIP gene and the influence of increased CacyBP/SIP level on gene expression pattern in colorectal cancer HCT116 cells

The CacyBP/SIP protein is expressed at a particularly high level in brain, spleen, and various tumors. In this work, we have studied transcriptional regulation of the CacyBP/SIP gene and the influence of increased CacyBP/SIP level on gene expression in colorectal cancer HCT116 cells. We have shown that E2F1, EGR1, and CREB transcription factors bind to the CacyBP/SIP gene promoter and stimulate transcription of CacyBP/SIP gene. The role of CREB was further confirmed by the observation that forskolin, a strong activator of CREB phosphorylation/activity, increased CacyBP/SIP gene promoter activity. Moreover, we have shown that CREB dominant negative mutants, CREB133 and KCREB, inhibits CacyBP/SIP promoter activity. To check the biological significance of increased CacyBP/SIP expression/level we have applied RNA microarray analysis and have found that upregulation of CacyBP/SIP entails changes in mRNA level of many genes involved, among others, in immune processes. © 2017 IUBMB Life, 70(1):50-59, 2018.

Transcription factors: Time to deliver

Transcription factors (TFs) are at the center of the broad regulatory network orchestrating gene expression programs that elicit different biological responses. For a long time, TFs have been considered as potent drug targets due to their implications in the pathogenesis of a variety of diseases. At the same time, TFs, located at convergence points of cellular regulatory pathways, are powerful tools providing opportunities both for cell type change and for managing the state of cells. This task formulation requires the TF modulation problem to come to the fore. We review several ways to manage TF activity (small molecules, transfection, nanocarriers, protein-based approaches), analyzing their limitations and the possibilities to overcome them. Delivery of TFs could revolutionize the biomedical field. Whether this forecast comes true will depend on the ability to develop convenient technologies for targeted delivery of TFs.

The extracellular matrix protein mindin attenuates colon cancer progression by blocking angiogenesis via Egr-1-mediated regulation

Mindin, a secreted, highly conserved extracellular matrix (ECM) protein, exerts a broad spectrum of effects on the innate immune system. However, its function in colorectal cancer (CRC) progression is not well established, and its upstream regulation mechanisms remain unclear. Contrary to previous reports, this study used two different enzyme-linked immunosorbent assay (ELISA) kits to show that the serum level of mindin was significantly decreased in CRC patients and that this decreased level is more significantly associated with the early stages of the disease. To explore the regulation of mindin, we used a bioinformatics approach to predict potential transcription factors and determined that early growth response factor (Egr)-1 directly regulates mindin expression at the transcriptional level using dual luciferase, chromatin immunoprecipitation (ChIP) DNA and electrophoretic mobility shift assay (EMSA) methods. Egr-1 regulates mindin mRNA and protein expression in CRC cells, and the protein expression of both Egr-1 and mindin was significantly decreased in tumor lesions of patients compared with adjacent control tissues. Mindin is essential for Egr-1-mediated inhibition of endothelial cell tube formation, and mindin inhibits endotheliocyte proliferation, migration and angiogenic sprouts in vitro. Overexpression of mindin suppressed xenograft tumor growth by blocking angiogenesis instead of directly suppressing CRC cell proliferation. Mechanically, mindin inhibits the hypoxia-induced HIF-1a and VEGFA protein expression in CRC cells and the phosphorylation of VEGFR-2 in endothelial cells. The results suggest that the serum level of mindin can be used as a novel biomarker for early detection of CRC and that the Egr-1/mindin axis is a potential therapeutic target for the inhibition of angiogenesis in CRC development.

Upregulation of CISD2 augments ROS homeostasis and contributes to tumorigenesis and poor prognosis of lung adenocarcinoma

CISD2 is a redox-sensitive gene critical for normal development and mitochondrial integrity. CISD2 was known to have aberrant expression in several types of human cancers. However, its relation with lung cancer is still not clear. In this study we found CISD2 mRNA was significantly upregulated in lung adenocarcinoma (ADC) samples, compared with their adjacent normal counterparts, and was correlated with tumor stage, grade, and prognosis based on analysis of clinical specimens-derived expression data in public domain and our validation assay. Cell based assay indicated that CISD2 expression regulated accumulation of reactive oxygen species (ROS), polarization of mitochondrial membrane potential, as well as cell viability, apoptosis, invasiveness, and tumorigenicity. In addition, CISD2 expression was found significantly correlated with stress response/redox signaling genes such as EGR1 and GPX3, while such correlations were also found valid in many public domain data. Taken together, upregulation of CISD2 is involved in an increased antioxidant capacity in response to elevated ROS levels during the formation and progression of lung ADC. The molecular mechanism underlying how CISD2 regulates ROS homeostasis and augments malignancy of lung cancer warrants further investigations.

CDKN2B deletion is essential for pancreatic cancer development instead of unmeaningful co-deletion due to juxtaposition to CDKN2A

Pancreatic cancer is among the deadliest malignancies; however, the genetic events that lead to pancreatic carcinogenesis in adults remain unclear. In vivo models in which these genetic alterations occur in adult animals may more accurately reflect the features of human cancer. In this study, we demonstrate that inactivation of Cdkn2b (p15ink4b) is necessary for induction of pancreatic cancer by oncogenic KRAS^G12D expression and inactivation of Tp53 and Cdkn2a in adult mouse pancreatic ductal cells (P60 or older). KRAS^G12D overexpression in these cells activated transforming growth factor-β signaling and expression of CDKN2B, which, along with CDKN2A, led to cellular senescence and protected cells from KRAS-mediated transformation via inhibition of retinoblastoma phosphorylation. These results show a critical role of CDKN2B inactivation in pancreatic carcinogenesis, and provide a useful adult animal model by genetic engineering via lentiviral delivery.

Loss of Egr1, a human del5q gene, accelerates BCR-ABL driven chronic myelogenous leukemia

There is substantial evidence that early growth response-1 (Egr1) gene, a zinc-finger transcription factor, behaves as a tumor suppressor in leukemia. This includes reports from this laboratory that constitutive Egr1 overrides leukemia conferred by deregulated c-Myc or E2F-1 in the M1 myeloid leukemic cell line by promoting differentiation. To investigate the effect of Egr1 on the initiation and progression of Chronic Myelogenous Leukemia (CML), lethally irradiated syngeneic wild type mice were reconstituted with bone marrow (BM) from either wild type or Egr1 null mice transduced with a 210-kD BCR-ABL-expressing MSCV-retrovirus (bone marrow transplantation {BMT}). Loss of Egr1 was observed to accelerate the development of BCR-ABL driven leukemia in recipient mice, resulting in the development of a more aggressive disease, a significantly shortened median survival time, and increased BCR-ABL expressing leukemic stem/progenitor cells (GFP+Lin-cKit+Sca+). Egr1 deficient progenitors expressing BCR-ABL exhibited decreased apoptosis, and increased cell viability and proliferation relative to WT counterparts. Secondary BMT of BCR-ABL BM revealed that loss of Egr1 resulted in enrichment of LSCs, consistent with shorter survival time and more aggressive disease of these mice compared to WT counterparts. Furthermore, serial re-plating colony assays indicated that loss of Egr1 increased self-renewal ability of BCR-ABL expressing BM. These novel findings on the tumor suppressor role of Egr1 in CML provide the impetus to study the effect of altering Egr1 expression in AML, where the overall five year survival rate remains low. The effect of loss of Egr1 in CML could reflect its established functions in normal hematopoiesis, maintaining quiescence of HSCs and driving terminal differentiation to the monocyte/macrophage lineage. Gain of function studies should validate these conclusions and provide further rationale for increased Egr1 as a therapeutic target in AML.

Genetic background-dependent role of Egr1 for eyelid development

EGR1 is an early growth response zinc finger transcription factor with broad actions, including in differentiation, mitogenesis, tumor suppression, and neuronal plasticity. Here we demonstrate that Egr1^-/- mice on the C57BL/6 background have normal eyelid development, but back-crossing to BALB/c background for four or five generations resulted in defective eyelid development by day E15.5, at which time EGR1 was expressed in eyelids of WT mice. Defective eyelid formation correlated with profound ocular anomalies evident by postnatal days 1-4, including severe cryptophthalmos, microphthalmia or anophthalmia, retinal dysplasia, keratitis, corneal neovascularization, cataracts, and calcification. The BALB/c albino phenotype-associated Tyr^c tyrosinase mutation appeared to contribute to the phenotype, because crossing the independent Tyr^c-2J allele to Egr1^-/- C57BL/6 mice also produced ocular abnormalities, albeit less severe than those in Egr1^-/- BALB/c mice. Thus EGR1, in a genetic background-dependent manner, plays a critical role in mammalian eyelid development and closure, with subsequent impact on ocular integrity.

EMT/MET at the Crossroad of Stemness, Regeneration and Oncogenesis: The Ying-Yang Equilibrium Recapitulated in Cell Spheroids

The epithelial-to-mesenchymal transition (EMT) is an essential trans-differentiation process, which plays a critical role in embryonic development, wound healing, tissue regeneration, organ fibrosis, and cancer progression. It is the fundamental mechanism by which epithelial cells lose many of their characteristics while acquiring features typical of mesenchymal cells, such as migratory capacity and invasiveness. Depending on the contest, EMT is complemented and balanced by the reverse process, the mesenchymal-to-epithelial transition (MET). In the saving economy of the living organisms, the same (Ying-Yang) tool is integrated as a physiological strategy in embryonic development, as well as in the course of reparative or disease processes, prominently fibrosis, tumor invasion and metastasis. These mechanisms and their related signaling (e.g., TGF-β and BMPs) have been effectively studied in vitro by tissue-derived cell spheroids models. These three-dimensional (3D) cell culture systems, whose phenotype has been shown to be strongly dependent on TGF-β-regulated EMT/MET processes, present the advantage of recapitulating in vitro the hypoxic in vivo micro-environment of tissue stem cell niches and their formation. These spheroids, therefore, nicely reproduce the finely regulated Ying-Yang equilibrium, which, together with other mechanisms, can be determinant in cell fate decisions in many pathophysiological scenarios, such as differentiation, fibrosis, regeneration, and oncogenesis. In this review, current progress in the knowledge of signaling pathways affecting EMT/MET and stemness regulation will be outlined by comparing data obtained from cellular spheroids systems, as ex vivo niches of stem cells derived from normal and tumoral tissues. The mechanistic correspondence in vivo and the possible pharmacological perspective will be also explored, focusing especially on the TGF-β-related networks, as well as others, such as SNAI1, PTEN, and EGR1. This latter, in particular, for its ability to convey multiple types of stimuli into relevant changes of the cell transcriptional program, can be regarded as a heterogeneous "stress-sensor" for EMT-related inducers (growth factor, hypoxia, mechano-stress), and thus as a therapeutic target.

Zika Virus Persistently Infects and Is Basolaterally Released from Primary Human Brain Microvascular Endothelial Cells

Zika virus (ZIKV) is a mosquito-borne Flavivirus that has emerged as the cause of encephalitis and fetal microencephaly in the Americas. ZIKV uniquely persists in human bodily fluids for up to 6 months, is sexually transmitted, and traverses the placenta and the blood-brain barrier (BBB) to damage neurons. Cells that support persistent ZIKV replication and mechanisms by which ZIKV establishes persistence remain enigmatic but central to ZIKV entry into protected neuronal compartments. The endothelial cell (EC) lining of capillaries normally constrains transplacental transmission and forms the BBB, which selectively restricts access of blood constituents to neurons. We found that ZIKV (strain PRVABC59) persistently infects and continuously replicates in primary human brain microvascular ECs (hBMECs), without cytopathology, for >9 days and following hBMEC passage. ZIKV did not permeabilize hBMECs but was released basolaterally from polarized hBMECs, suggesting a direct mechanism for ZIKV to cross the BBB. ZIKV-infected hBMECs were rapidly resistant to alpha interferon (IFN-α) and transiently induced, but failed to secrete, IFN-β and IFN-λ. Global transcriptome analysis determined that ZIKV constitutively induced IFN regulatory factor 7 (IRF7), IRF9, and IFN-stimulated genes (ISGs) 1 to 9 days postinfection, despite persistently replicating in hBMECs. ZIKV constitutively induced ISG15, HERC5, and USP18, which are linked to hepatitis C virus (HCV) persistence and IFN regulation, chemokine CCL5, which is associated with immunopathogenesis, as well as cell survival factors. Our results reveal that hBMECs act as a reservoir of persistent ZIKV replication, suggest routes for ZIKV to cross hBMECs into neuronal compartments, and define novel mechanisms of ZIKV persistence that can be targeted to restrict ZIKV spread.IMPORTANCE ZIKV persists in patients, crossing placental and neuronal barriers, damaging neurons, and causing fetal microencephaly. We found that ZIKV persistently infects brain endothelial cells that normally protect neurons from viral exposure. hBMECs are not damaged by ZIKV infection and, analogous to persistent HCV infection, ZIKV constitutively induces and evades antiviral ISG and IFN responses to continuously replicate in hBMECs. As a result, hBMECs provide a protective niche for systemic ZIKV spread and a viral reservoir localized in the normally protective blood-brain barrier. Consistent with the spread of ZIKV into neuronal compartments, ZIKV was released basolaterally from hBMECs. Our findings define hBMEC responses that contribute to persistent ZIKV infection and potential targets for clearing ZIKV infections from hBMECs. These results further suggest roles for additional ZIKV-infected ECs to facilitate viral spread and persistence in the protected placental, retinal, and testicular compartments.

Universal attenuators and their interactions with feedback loops in gene regulatory networks

Using a combination of mathematical modelling, statistical simulation and large-scale data analysis we study the properties of linear regulatory chains (LRCs) within gene regulatory networks (GRNs). Our modelling indicates that downstream genes embedded within LRCs are highly insulated from the variation in expression of upstream genes, and thus LRCs act as attenuators. This observation implies a progressively weaker functionality of LRCs as their length increases. When analyzing the preponderance of LRCs in the GRNs of Escherichia coli K12 and several other organisms, we find that very long LRCs are essentially absent. In both E. coli and M. tuberculosis we find that four-gene LRCs are intimately linked to identical feedback loops that are involved in potentially chaotic stress response, indicating that the dynamics of these potentially destabilising motifs are strongly restrained under homeostatic conditions. The same relationship is observed in a human cancer cell line (K562), and we postulate that four-gene LRCs act as ‘universal attenuators’. These findings suggest a role for long LRCs in dampening variation in gene expression, thereby protecting cell identity, and in controlling dramatic shifts in cell-wide gene expression through inhibiting chaos-generating motifs.

Curcumin mediates anticancer effects by modulating multiple cell signaling pathways

Curcumin, a component of a spice native to India, was first isolated in 1815 by Vogel and Pelletier from the rhizomes of Curcuma longa (turmeric) and, subsequently, the chemical structure of curcumin as diferuloylmethane was reported by Milobedzka et al. [(1910) 43., 2163-2170]. Since then, this polyphenol has been shown to exhibit antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, and antifungal activities. The current review primarily focuses on the anticancer potential of curcumin through the modulation of multiple cell signaling pathways. Curcumin modulates diverse transcription factors, inflammatory cytokines, enzymes, kinases, growth factors, receptors, and various other proteins with an affinity ranging from the pM to the mM range. Furthermore, curcumin effectively regulates tumor cell growth via modulation of numerous cell signaling pathways and potentiates the effect of chemotherapeutic agents and radiation against cancer. Curcumin can interact with most of the targets that are modulated by FDA-approved drugs for cancer therapy. The focus of this review is to discuss the molecular basis for the anticancer activities of curcumin based on preclinical and clinical findings.

Impairment of the activin A autocrine loop by lopinavir reduces self-renewal of distinct human adipose progenitors

Maintenance of the adipose tissue requires a proper balance between self-renewal and differentiation of adipose progenitors (AP). Any deregulation leads either to fat overexpansion and obesity or fat loss and consequent lipodystrophies. Depending on the fat pad location, APs and adipocytes are heterogeneous. However, information on the pharmacological sensitivity of distinct APs to drugs known to alter the function of adipose tissue, especially HIV protease inhibitors (PIs) is scant. Here we show that PIs decreased proliferation and clonal expansion of APs, modifying their self-renewal potential. Lopinavir was the most potent PI tested. Decrease in self-renewal was accompanied by a reduced expression of the immediate early response gene IER3, a gene associated with tissue expansion. It was more pronounced in chin-derived APs than in knee-derived APs. Furthermore, lopinavir lowered the activin A–induced ERK1/2 phosphorylation. Expressions of the transcription factor EGR1 and its targets, including INHBA were subsequently altered. Therefore, activin A secretion was reduced leading to a dramatic impairment of APs self-renewal sustained by the activin A autocrine loop. All together, these observations highlight the activin A autocrine loop as a crucial effector to maintain APs self-renewal. Targeting this pathway by HIV-PIs may participate in the induction of unwanted side effects.

Mechanisms of modulation of the Egr gene family in mammary epithelial cells of different species

In the adult female, within the estrous cycle, the mammary gland undergoes multiple rounds of growth, with increased cellular proliferation, and involution, with increased apoptosis. The increase in proliferation is elicited by endocrine (Estrogen, Progesterone), as well as locally produced (epidermal growth factor, insulin-like growth factor, etc) growth factors. Among the genes that are modulated during cellular proliferation, immediate early genes play a fundamental role, being rapidly upregulated and then downregulated within the G0/G1 phase of the cell cycle, allowing the progression to the subsequent phases. Egrs (1-4) are immediate early genes that encode for transcription factors that promote, within different cell types and depending on the strength and duration of the stimuli, several different responses like mitogenesis, differentiation, apoptosis or even anti-apoptosis. In this work we have studied the mechanisms of modulation of the Egr family, in mammary epithelial cells of different origin (bovine, canine, feline, murine). Following stimulation with growth medium, Egr mRNA expression showed a strong upregulation reaching a peak at 45-60min, that rapidly declined. Among several cytokines, particularly important for mammary morphogenesis, that we have tested (EGF, IGF-I, insulin, estrogen, progesterone), only EGF upregulated Egrs to levels close to those elicited by growth medium. In order to understand how the Egr transcription factors were regulated, we have inhibited Erk 1/2 and PI3K, molecules that drive two major intracellular signaling pathways. Inhibition of the Erk 1/2 pathway totally abolished Egr upregulation mediated by growth medium or EGF. On the other hand, the PI3K-Akt pathway played a minor role on Egr levels, with a strong inhibitory effect on cat GH2 cells only, that could be ascribed to reduced Erk phosphorylation following PI3K inhibition. Finally we showed that addition of growth medium also upregulated that the mammary luminal marker cytokeratin 18, but only in the murine NMuMG cell line. This is the first manuscript describing how the Egr transcription factors are expressed in mammary epithelial cells of domestic animals and which growth factors and signaling pathways modulate their expression.

Up-Regulation of Follistatin-Like 1 By the Androgen Receptor and Melanoma Antigen-A11 in Prostate Cancer

BACKGROUND

High affinity androgen binding to the androgen receptor (AR) activates genes required for male sex differentiation and promotes the development and progression of prostate cancer. Human AR transcriptional activity involves interactions with coregulatory proteins that include primate-specific melanoma antigen-A11 (MAGE-A11), a coactivator that increases AR transcriptional activity during prostate cancer progression to castration-resistant/recurrent prostate cancer (CRPC).

METHODS

Microarray analysis and quantitative RT-PCR were performed to identify androgen-regulated MAGE-A11-dependent genes in LAPC-4 prostate cancer cells after lentivirus shRNA knockdown of MAGE-A11. Chromatin immunoprecipitation was used to assess androgen-dependent AR recruitment, and immunocytochemistry to localize an androgen-dependent protein in prostate cancer cells and tissue and in the CWR22 human prostate cancer xenograft.

RESULTS

Microarray analysis of androgen-treated LAPC-4 prostate cancer cells indicated follistatin-like 1 (FSTL1) is up-regulated by MAGE-A11. Androgen-dependent up-regulation of FSTL1 was inhibited in LAPC-4 cells by lentivirus shRNA knockdown of AR or MAGE-A11. Chromatin immunoprecipitation demonstrated AR recruitment to intron 10 of the FSTL1 gene that contains a classical consensus androgen response element. Increased levels of FSTL1 protein in LAPC-4 cells correlated with higher levels of MAGE-A11 relative to other prostate cancer cells. FSTL1 mRNA levels increased in CRPC and castration-recurrent CWR22 xenografts in association with predominantly nuclear FSTL1. Increased nuclear localization of FSTL1 in prostate cancer was suggested by predominantly cytoplasmic FSTL1 in benign prostate epithelial cells and predominantly nuclear FSTL1 in epithelial cells in CRPC tissue and the castration-recurrent CWR22 xenograft. AR expression studies showed nuclear colocalization of AR and endogenous FSTL1 in response to androgen.

CONCLUSION

AR and MAGE-A11 cooperate in the up-regulation of FSTL1 to promote growth and progression of CRPC. Prostate 77:505-516, 2017. © 2016 Wiley Periodicals, Inc.

Fasting regulates EGR1 and protects from glucose- and dexamethasone-dependent sensitization to chemotherapy

Fasting reduces glucose levels and protects mice against chemotoxicity, yet drugs that promote hyperglycemia are widely used in cancer treatment. Here, we show that dexamethasone (Dexa) and rapamycin (Rapa), commonly administered to cancer patients, elevate glucose and sensitize cardiomyocytes and mice to the cancer drug doxorubicin (DXR). Such toxicity can be reversed by reducing circulating glucose levels by fasting or insulin. Furthermore, glucose injections alone reversed the fasting-dependent protection against DXR in mice, indicating that elevated glucose mediates, at least in part, the sensitizing effects of rapamycin and dexamethasone. In yeast, glucose activates protein kinase A (PKA) to accelerate aging by inhibiting transcription factors Msn2/4. Here, we show that fasting or glucose restriction (GR) regulate PKA and AMP-activated protein kinase (AMPK) to protect against DXR in part by activating the mammalian Msn2/4 ortholog early growth response protein 1 (EGR1). Increased expression of the EGR1-regulated cardioprotective peptides atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in heart tissue may also contribute to DXR resistance. Our findings suggest the existence of a glucose-PKA pathway that inactivates conserved zinc finger stress-resistance transcription factors to sensitize cells to toxins conserved from yeast to mammals. Our findings also describe a toxic role for drugs widely used in cancer treatment that promote hyperglycemia and identify dietary interventions that reverse these effects.

Evolving Transcription Factor Binding Site Models From Protein Binding Microarray Data

Protein binding microarray (PBM) is a high-throughput platform that can measure the DNA binding preference of a protein in a comprehensive and unbiased manner. In this paper, we describe the PBM motif model building problem. We apply several evolutionary computation methods and compare their performance with the interior point method, demonstrating their performance advantages. In addition, given the PBM domain knowledge, we propose and describe a novel method called kmerGA which makes domain-specific assumptions to exploit PBM data properties to build more accurate models than the other models built. The effectiveness and robustness of kmerGA is supported by comprehensive performance benchmarking on more than 200 datasets, time complexity analysis, convergence analysis, parameter analysis, and case studies. To demonstrate its utility further, kmerGA is applied to two real world applications: 1) PBM rotation testing and 2) ChIP-Seq peak sequence prediction. The results support the biological relevance of the models learned by kmerGA, and thus its real world applicability.

Egr-1 regulates irradiation-induced autophagy through Atg4B to promote radioresistance in hepatocellular carcinoma cells

Although hepatocellular carcinoma (HCC) is usually response to radiation therapy, radioresistance is still the major obstacle that limits the efficacy of radiotherapy for HCC patients. Therefore, further investigation of underlying mechanisms in radioresistant HCC cells is warranted. In this study, we determined the effect of early growth response factor (Egr-1) on irradiation-induced autophagy and radioresistance in HCC cell lines SMMC-7721 and HepG2. We showed that autophagy-related gene 4B (Atg4B) is induced by Egr-1 upon ionizing radiation (IR) in HCC cells. Luciferase reporter assays and chromatin immunoprecipitation (ChIP) revealed that Egr-1 binds to the Atg4B promoter to upregulate its expression in HCC cells. Suppression of Egr-1 function by dominant-negative Egr-1 dampens IR-induced autophagy, cell migration, and increases cell sensitivity to radiotherapy. Together, these results suggest that Egr-1 contributes to HCC radioresistance through directly upregulating target gene Atg4B, which may serve as a protective mechanism by preferential activation of the autophagy.

The Host Cell Transcription Factor EGR1 Is Induced by Bacteria through the EGFR-ERK1/2 Pathway

The essential first step in bacterial colonization is adhesion to the host epithelial cells. The early host-responses post-bacterial adhesions are still poorly understood. Early growth response 1 (EGR1) is an early response transcriptional regulator that can be rapidly induced by various environmental stimuli. Several bacteria can induce EGR1 expression in host cells, but the involved bacterial characteristics and the underlying molecular mechanisms of this response are largely unknown. Here, we show that EGR1 can be induced in host epithelial cells by different species of bacteria independent of the adherence level, Gram-staining type and pathogenicity. However, bacterial viability and contact with host cells is necessary, indicating that an active interaction between bacteria and the host is important. Furthermore, the strongest response is observed in cells originating from the natural site of the infection, suggesting that the EGR1 induction is cell type specific. Finally, we show that EGFR–ERK1/2 and β1-integrin signaling are the main pathways used for bacteria-mediated EGR1 upregulation. In conclusion, the increase of EGR1 expression in epithelial cells is a common stress induced, cell type specific response upon host-bacteria interaction that is mediated by EGFR–ERK1/2 and β1-integrin signaling.

Clair DK, Rangnekar VM, Bondada S. Radiation Induced Apoptosis of Murine Bone Marrow Cells Is Independent of Early Growth Response 1 (EGR1)

An understanding of how each individual 5q chromosome critical deleted region (CDR) gene contributes to malignant transformation would foster the development of much needed targeted therapies for the treatment of therapy related myeloid neoplasms (t-MNs). Early Growth Response 1 (EGR1) is a key transcriptional regulator of myeloid differentiation located within the 5q chromosome CDR that has been shown to regulate HSC (hematopoietic stem cell) quiescence as well as the master regulator of apoptosis—p53. Since resistance to apoptosis is a hallmark of malignant transformation, we investigated the role of EGR1 in apoptosis of bone marrow cells; a cell population from which myeloid malignancies arise. We evaluated radiation induced apoptosis of Egr1^+/+ and Egr1^-/- bone marrow cells in vitro and in vivo. EGR1 is not required for radiation induced apoptosis of murine bone marrow cells. Neither p53 mRNA (messenger RNA) nor protein expression is regulated by EGR1 in these cells. Radiation induced apoptosis of bone marrow cells by double strand DNA breaks induced p53 activation. These results suggest EGR1 dependent signaling mechanisms do not contribute to aberrant apoptosis of malignant cells in myeloid malignancies.

DNA methylation profile of triple negative breast cancer-specific genes comparing lymph node positive patients to lymph node negative patients

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with no targeted treatment available. Our previous study identified 38 TNBC-specific genes with altered expression comparing tumour to normal samples. This study aimed to establish whether DNA methylation contributed to these expression changes in the same cohort as well as disease progression from primary breast tumour to lymph node metastasis associated with changes in the epigenome. We obtained DNA from 23 primary TNBC samples, 12 matched lymph node metastases, and 11 matched normal adjacent tissues and assayed for differential methylation profiles using Illumina HumanMethylation450 BeadChips. The results were validated in an independent cohort of 70 primary TNBC samples. The expression of 16/38 TNBC-specific genes was associated with alteration in DNA methylation. Novel methylation changes between primary tumours and lymph node metastases, as well as those associated with survival were identified. Altered methylation of 18 genes associated with lymph node metastasis were identified and validated. This study reveals the important role DNA methylation plays in altered gene expression of TNBC-specific genes and lymph node metastases. The novel insights into progression of TNBC to secondary disease may provide potential prognostic indicators for this hard-to-treat breast cancer subtype.

Age-associated up-regulation of EGR1 promotes granulosa cell apoptosis during follicle atresia in mice through the NF-κB pathway

Follicular atresia is the main process responsible for the loss of follicles and oocytes from the ovary, and it is the root cause of ovarian aging. Apoptosis of granulosa cells (GCs) is the cellular mechanism responsible for follicular atresia in mammals. Recent advances have highlighted fundamental roles for EGR1 in age-related diseases via the induction of apoptosis. In the present study, we found that the expression of EGR1 was significantly increased in aged mouse ovaries compared with young ovaries. Immunohistochemical analysis revealed strongly positive EGR1 staining in atretic follicles, especially in apoptotic granulosa cells. We further showed that EGR1 up-regulation in mouse primary granulosa cells inhibited cell proliferation and promoted apoptosis. In addition, the promotion of apoptosis in GCs by EGR1 increases over time and with reactive oxygen species (ROS) stimulation. Our mechanistic study suggested that EGR1 regulates GC apoptosis in a mitochondria-dependent manner and that this mainly occurs through the NF-κB signaling pathway. In conclusion, our results suggested that age-related up-regulation of EGR1 promotes GC apoptosis in follicle atresia during ovarian aging.

Hallmarks of cancer and AU-rich elements

Post‐transcriptional control of gene expression is aberrant in cancer cells. Sustained stabilization and enhanced translation of specific mRNAs are features of tumor cells. AU‐rich elements (AREs), cis‐acting mRNA decay determinants, play a major role in the posttranscriptional regulation of many genes involved in cancer processes. This review discusses the role of aberrant ARE‐mediated posttranscriptional processes in each of the hallmarks of cancer, including sustained cellular growth, resistance to apoptosis, angiogenesis, invasion, and metastasis. WIREs RNA 2017, 8:e1368. doi: 10.1002/wrna.1368

For further resources related to this article, please visit the WIREs website.

The progress of early growth response factor 1 and leukemia

Early growth response gene-1 (EGR1) widely exists in the cell nucleus of such as, zebrafish, mice, chimpanzees and humans, an it also can be observed in the cytoplasm of some tumors. EGR1 was named just after its brief and rapid expression of different stimuli. Accumulating studies have extensively demonstrated that the widespread dysregulation of EGR1 is involved in hematological malignancies such as human acute myeloid leukemia (AML), chronic myelogenous leukemia, chronic lymphocytic leukemia, multiple myeloma, and B cell lymphoma. With the deep research on EGR1, its expression, function and regulatory mechanism has been gradually elucidated, and provides more possibilities for treatment strategies of patients with leukemia. Herein, we summarize the roles of EGR1 in its biological function and relationship with leukemia.

The role of microRNA in metastatic processes of non-small cell lung carcinoma

BACKGROUND

MicroRNAs are small non-coding one-stranded RNA molecules that play an important role in the post-transcriptional regulation of genes. Bioinformatic predictions indicate that each miRNA can regulate hundreds of target genes. MicroRNA expression can be associated with various cellular processes leading to the metastasis of malignant tumours including non-small cell lung carcinoma. This review summarizes current knowledge on the role of microRNAs in NSCLC metastasis to the brain and lymph nodes.

METHODS

A search of the NCBI/PubMed database for publications on expression levels and the mechanisms of microRNA action in NSCLC metastasis.

RESULTS AND CONCLUSION

Dysregulation of microRNAs in NSCLC can be associated with brain and lymph node metastasis. There are differences in microRNA expression profiling between NSCLC with and without metastases but it is currently not possible to reliably predict the site of metastasis in NSCLC. Based on data from RNAmicroarrays, bioinformatics analysis is able to predict the target genes of highlighted microRNAs, providing us with complex information about cancer cell features such as enhanced proliferation, migration and invasion. Such microRNAs may then be knocked-down using siRNAs or substituted with miRNA mimics. RNA microarray profiling may thus be a useful tool to select up- or down-regulated microRNAs. A number of authors suggest that microRNAs could serve as biomarkers and therapeutic targets in the treatment of NSCLC metastasis.

Phosphatase and tensin homolog is a differential diagnostic marker between nonalcoholic and alcoholic fatty liver disease

AIM: To investigate the protein expression of phosphatase and tensin homolog (PTEN) in human liver biopsies of patients with alcoholic and non-alcoholic liver disease.

METHODS: PTEN protein expression was assessed by immunohistochemistry in formalin-fixed, paraffin-embedded liver sections of patients with non-alcoholic fatty liver disease (NAFLD) (n = 44) or alcoholic liver disease (ALD) (n = 25). Liver resections obtained from 3 healthy subjects candidate for partial liver donation served as controls. Histological evaluations were performed by two experienced pathologists, and diagnoses established based on international criteria. The intensity of the PTEN staining in nuclei was compared between steatotic and non-steatotic areas of each liver fragment analyzed. For each liver specimen, the antibody-stained sections were examined and scored blindly by three independent observers, who were unaware of the patients’ clinical history.

RESULTS: In healthy individuals, PTEN immunostaining was intense in both the cytoplasm and nuclei of all hepatocytes. However, PTEN was strongly downregulated in both the nucleus and the cytoplasm of hepatocytes from steatotic areas in patients with NAFLD, independently of the disease stage. In contrast, no changes in PTEN protein expression were observed in patients with ALD, regardless of the presence of steatosis or the stage of the disease. The degree of PTEN downregulation in hepatocytes of patients with NAFLD correlated with the percentage of steatosis (r = 0.3061, P = 0.0459) and the BMI (r = 0.4268, P = 0.0043). Hovewer, in patients with ALD, PTEN expression was not correlated with the percentage of steatosis with or without obesity as a confounding factor (P = 0.5574). Finally, PTEN expression level in steatotic areas of ALD patients was significantly different from that seen in steatotic areas of NAFLD patients (P < 0.0001).

CONCLUSION: PTEN protein expression is downregulated early in NAFLD, but not in ALD. PTEN immunohistochemical detection could help in the differential diagnosis of NAFLD and ALD.

IMP1 suppresses breast tumor growth and metastasis through the regulation of its target mRNAs

We have previously reported the ability of IMP1 in inhibiting proliferation and invasiveness of breast carcinoma cells in vitro. In the current study, we utilized a mouse xenograft model to further investigate the function of IMP1 in breast tumor progression and its underlying mechanism. We demonstrated that IMP1 expression significantly suppressed the growth of MDA231 cell-derived xenograft tumors and subsequent lung metastasis. Microarray analyses and differential gene expression identified handful mRNAs, many of which were involved in breast tumor-growth and metastasis. Further studies revealed that these mRNAs were directly interacted with the KH34 domain of IMP1 and this interaction post-transcriptionally regulated their corresponding protein expression. Either deletion of the KH34 domain of IMP1 or alteration of the expression of IMP1-bound mRNAs affected cell proliferation and tumor growth, producing the same phenotypes as IMP1 knockdown. Correlation of increased IMP1 expression with the reduced levels of its bound mRNAs, such as PTGS2, GDF15 and IGF-2 transcripts, was also observed in human breast tumors. Our studies provide insights into a molecular mechanism that the positive function of IMP1 to inhibit breast tumor growth and metastasis could be through the regulation of its target mRNAs.

A Comparison Study for DNA Motif Modeling on Protein Binding Microarray

Transcription factor binding sites (TFBSs) are relatively short (5-15 bp) and degenerate. Identifying them is a computationally challenging task. In particular, protein binding microarray (PBM) is a high-throughput platform that can measure the DNA binding preference of a protein in a comprehensive and unbiased manner; for instance, a typical PBM experiment can measure binding signal intensities of a protein to all possible DNA k-mers (k = 8∼10). Since proteins can often bind to DNA with different binding intensities, one of the major challenges is to build TFBS (also known as DNA motif) models which can fully capture the quantitative binding affinity data. To learn DNA motif models from the non-convex objective function landscape, several optimization methods are compared and applied to the PBM motif model building problem. In particular, representative methods from different optimization paradigms have been chosen for modeling performance comparison on hundreds of PBM datasets. The results suggest that the multimodal optimization methods are very effective for capturing the binding preference information from PBM data. In particular, we observe a general performance improvement if choosing di-nucleotide modeling over mono-nucleotide modeling. In addition, the models learned by the best-performing method are applied to two independent applications: PBM probe rotation testing and ChIP-Seq peak sequence prediction, demonstrating its biological applicability.

Epigenetic silencing of BCL6B inactivates p53 signaling and causes human hepatocellular carcinoma cell resist to 5-FU

BCL6B is a potential tumor suppressor in human gastric cancer, but the regulation and mechanism of BCL6B in human hepatocellular carcinogenesis remain unclear. This study is to explore the epigenetic change and mechanism of BCL6B in human hepatocellular carcinoma (HCC). Nineteen hepatic cancer cell lines, 50 cases of adjacent tissue and 149 cases of HCC samples were employed. BCL6B is methylated in 100% (19/19) of human HCC cell lines, 40.0% (20/50) of adjacent tissue samples and 86.6% (129/149) of primary cancer samples. Methylation of BCL6B is associated with HBV positive (p < 0.05). But no association was found with age, sex, tumor size, differentiation, TNM stage, recurrence and survival. Loss of BCL6B expression was found in 19 of completely methylated HCC cell lines. BCL6B was re-expressed after 5-aza-2′-deoxycytidine treatment. Restoration of BCL6B expression suppressed cell proliferation, induced apoptosis and G1/S arrest in HCC cells. The expression of EGR1, a key component of p53 signaling, was increased after re-expression BCL6B in HCC cells. Re-expression of BCL6B activated p53 signaling and sensitized HCC cells to 5-fluorouracil. BCL6B is frequently methylated in human HCC and the expression of BCL6B is regulated by promoter region hypermethylation. BCL6B activates p53 signaling by increasing EGR1 expression in HCC.

4EBP1/c-MYC/PUMA and NF-κB/EGR1/BIM pathways underlie cytotoxicity of mTOR dual inhibitors in malignant lymphoid cells

The mammalian target of rapamycin (mTOR), a kinase that regulates proliferation and apoptosis, has been extensively evaluated as a therapeutic target in multiple malignancies. Rapamycin analogs, which partially inhibit mTOR complex 1 (mTORC1), exhibit immunosuppressive and limited antitumor activity, but sometimes activate survival pathways through feedback mechanisms involving mTORC2. Thus, attention has turned to agents targeting both mTOR complexes by binding the mTOR active site. Here we show that disruption of either mTOR-containing complex is toxic to acute lymphocytic leukemia (ALL) cells and identify 2 previously unrecognized pathways leading to this cell death. Inhibition of mTORC1-mediated 4EBP1 phosphorylation leads to decreased expression of c-MYC and subsequent upregulation of the proapoptotic BCL2 family member PUMA, whereas inhibition of mTORC2 results in nuclear factor-κB-mediated expression of the Early Growth Response 1 (EGR1) gene, which encodes a transcription factor that binds and transactivates the proapoptotic BCL2L11 locus encoding BIM. Importantly, 1 or both pathways contribute to death of malignant lymphoid cells after treatment with dual mTORC1/mTORC2 inhibitors. Collectively, these observations not only provide new insight into the survival roles of mTOR in lymphoid malignancies, but also identify alterations that potentially modulate the action of mTOR dual inhibitors in ALL.

Egr-1 identifies neointimal remodeling and relates to progression in human pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is hallmarked by the development of neointimal lesions. The transcription factor Egr-1 seems to play a critical role in neointimal formation in experimental PAH and was identified as a putative target for intervention. In this study we investigated whether Egr-1 is also associated with neointimal-type vascular remodeling in different forms of human PAH or pulmonary hypertension.

METHODS

Using immunohistochemistry, we studied Egr-1 expression specifically in a wide morphologic spectrum of pulmonary arteries in the lung tissue of 72 patients with different forms and stages of PAH, specifically idiopathic PAH (n = 18), advanced-stage congenital heart disease‒associated PAH (PAH-CHD) (n = 21), early-stage PAH-CHD (n = 19) and non-neointimal hypoxic pulmonary hypertension (PH) (n = 4), and controls (n = 10).

RESULTS

In PAH patients, pulmonary vascular expression of Egr-1 protein was abundant, whereas it was sporadic in non-neointimal (hypoxic) PH patients and controls. In PAH-CHD, protein expression was more pronounced in patients with advanced vascular lesions compared to those with less advanced lesions, such as medial hypertrophy.

CONCLUSIONS

Pulmonary vascular Egr-1 expression is significantly increased in patients with PAH, appears specifically associated with neointimal-type vascular remodeling, and correlates with disease progression. These data translate the critical role of Egr-1 in the development of experimental PAH to human pulmonary vascular disease forms.

Plasma miR-183 predicts recurrence and prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies worldwide. The prognosis for this cancer is poor, and the development of novel biomarkers, particularly non-invasive surrogate biomarkers, is urgently needed. Recent studies have demonstrated that microRNAs (miRNAs) are stably detectable in the blood and can serve as useful biomarkers for various types of cancer. In this study, the miR-183 expression levels were found to be significantly overexpressed in plasma samples from CRC patients compared with controls, and the postoperative plasma miR-183 levels were significantly reduced compared with the preoperative levels. The value of the area under the receiver operating characteristic (ROC) curve obtained for miR-183 was 0.829, which was higher than those for carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). High plasma miR-183 expression was significantly associated with lymph node metastasis, distant metastasis, higher pTNM stage (III-IV), and tumor recurrence. CRC patients with elevated miR-183 expression in plasma displayed shorter disease-free survival (DFS) and lower overall survival (OS). More importantly, plasma miR-183 was independently correlated with tumor recurrence and a lower OS. Collectively, our results suggested that the elevated miR-183 in the plasma could be a promising biomarker for predicting the risk of tumor recurrence and poor survival in CRC patients.

The expression of B23 and EGR1 proteins is functionally linked in tumor cells under stress conditions

BACKGROUND

The nucleolus is a multi-domain enriched with proteins involved in ribosome biogenesis, cell cycle and apoptosis control, viral replication and differentiation of stem cells. Several authors have suggested a role for the nucleolus also in malignant transformation. We have recently demonstrated that under specific circumstances the transcriptional factor EGR1 is shuttled to the nucleolus where it functions as a negative regulator of RNA polymerase I. Since this activity is hampered in ARF -/- cells, and ARF transcription is regulated by EGR1 while the turnover of ARF protein is under the control of B23, we speculated that some sort of cooperation between EGR1 and B23 might also exist.

RESULTS

In this work we identified a canonical EGR1 binding site on the B23 promoter through experiments of transactivation and in vitro DNA binding assay. We then found that the levels of B23 expression are directly correlated with those of EGR1, and that this correlation applies to several cellular types and to different stress conditions. Furthermore, we showed that EGR1 stability and accumulation within the nucleolus is in turn regulated by B23 through proteasome involvement, similarly to ARF turnover.

CONCLUSION

Our results highlight EGR1 as a regulator of B23 expression actively playing within the newly discovered nucleolar B23-ARF-EGR1 network.

Induction of apoptosis by genipin inhibits cell proliferation in AGS human gastric cancer cells via Egr1/p21 signaling pathway

Natural compounds are becoming important candidates in cancer therapy due to their cytotoxic effects on cancer cells by inducing various types of programmed cell deaths. In this study, we investigated whether genipin induces programmed cell deaths and mediates in Egr1/p21 signaling pathways in gastric cancer cells. Effects of genipin in AGS cancer cell lines were observed via evaluation of cell viability, ROS generation, cell cycle arrest, and protein and RNA levels of p21, Egr1, as well as apoptotic marker genes. The cell viability of AGS cells reduced by genipin treatment via induction of the caspase 3-dependent apoptosis. Cell cycle arrest was observed at the G2/M phase along with induction of p21 and p21-dependent cyclins. As an upstream mediator of p21, the transcription factor early growth response-1 (Egr1) upregulated p21 through nuclear translocation and binding to the p21 promoter site. Silencing Egr1 expression inhibited the expression of p21 and downstream molecules involved in apoptosis. We demonstrated that genipin treatment in AGS human gastric cancer cell line induces apoptosis via p53-independent Egr1/p21 signaling pathway in a dose-dependent manner.

On the effects of CP 55-940 and other cannabinoid receptor agonists in C6 and U373 cell lines

Cannabinoid receptor (CBs) agonists affect the growth of tumor cells via activation of deadly cascades. The spectrum of action of these agents and the precise role of the endocannabinoid system (ECS) on oncogenic processes remain elusive. Herein we compared the effects of synthetic (CP 55-940 and WIN 55,212-2) and endogenous (anandamide or AEA) CBs agonists (10-20 μM) on morphological changes, cell viability, and induction of apoptosis in primary astrocytes and in two glioblastoma cell lines (C6 and U373 cells) in order to characterize their possible differential actions on brain tumor cells. None of the CBs agonist tested induced changes in cell viability or morphology in primary astrocytes. In contrast, CP 55-940 significantly decreased cell viability in C6 and U373 cells at 5 days of treatment, whereas AEA and WIN 55,212-2 moderately decreased cell viability in both cell lines. Treatment of U373 and C6 for 3 and 5 days with AEA or WIN 55,212-2 produced discrete morphological changes in cell bodies, whereas the exposure to CP 55-940 induced soma degradation. CP 55-940 also induced apoptosis in both C6 and U373 cell lines. Our results support a more effective action of CP 55-940 to produce cell death of both cell lines through apoptotic mechanisms. Comparative aspects between cannabinoids with different profiles are necessary for the design of potential treatments against glial tumors.

CDKN2B Loss Promotes Progression from Benign Melanocytic Nevus to Melanoma

Deletion of the entire CDKN2B-CDKN2A gene cluster is among the most common genetic events in cancer. The tumor-promoting effects are generally attributed to loss of CDKN2A-encoded p16 and p14ARF tumor suppressors. The degree to which the associated CDKN2B-encoded p15 loss contributes to human tumorigenesis is unclear. Here, we show that CDKN2B is highly upregulated in benign melanocytic nevi, contributes to maintaining nevus melanocytes in a growth-arrested premalignant state, and is commonly lost in melanoma. Using primary melanocytes isolated directly from freshly excised human nevi naturally expressing the common BRAF(V600E)-activating mutation, nevi progressing to melanoma, and normal melanocytes engineered to inducibly express BRAF(V600E), we show that BRAF activation results in reversible, TGFβ-dependent, p15 induction that halts proliferation. Furthermore, we engineer human skin grafts containing nevus-derived melanocytes to establish a new, architecturally faithful, in vivo melanoma model, and demonstrate that p15 loss promotes the transition from benign nevus to melanoma.

SIGNIFICANCE

Although BRAF(V600E) mutations cause melanocytes to initially proliferate into benign moles, mechanisms responsible for their eventual growth arrest are unknown. Using melanocytes from human moles, we show that BRAF activation leads to a CDKN2B induction that is critical for restraining BRAF oncogenic effects, and when lost, contributes to melanoma.