Negative regulation of cyclin D3 expression by transcription factor c-Ets1 in umbilical cord hematopoietic cells

Vimentin affects colorectal cancer proliferation, invasion, and migration via regulated by activator protein 1

Uncontrolled recurrence and metastasis are important reasons for the high mortality rate of malignant tumors. Vimentin is positively correlated with the degree of malignancy of cancer cells. Vimentin is also highly expressed in colorectal cancer (CRC) cells and plays a critical role in the metastasis and prognosis of CRC. However, the molecular mechanism of vimentin in the progression of CRC is incompletely understood. Therefore, the most active regions (nucleotides: 785-1085 nt) of the vimentin promoter in CRC were identified using luciferase experiments. By transcription factor sequence search and mutation analysis, the activator protein 1 (AP-1) binding site in the region of 785-1085 nt was confirmed. The vimentin promoter activity was enhanced by overexpression of AP-1. The electrophoretic mobility shift assay and chromatin immunoprecipitation assay showed that the binding site was recognized by AP-1. By cell proliferation assay, colony-forming assay, scratch-wound assay, cell migration assay, and cell invasion assay, we demonstrated that the AP-1 overexpression increased CRC cell proliferation, migration, and invasion. However, when vimentin was knocked down by vimentin small hairpin RNA in the CRC cell of AP-1 overexpression, this trend disappeared. Animal experiments and immunohistochemistry showed that AP-1 promoted tumor growth by regulating the vimentin gene. In summary, AP-1 affected metastasis, invasion of CRC cells in vitro, and tumor growth in vivo by activating the vimentin promoter. This study might provide new insights into the molecular mechanisms of the development of CRC and provide potential therapeutic targets for CRC.

Inhibitory effect of PXR on ammonia-induced hepatocyte autophagy via P53

Pregnane X Receptor (PXR), a nuclear receptor transcription factor, participates in a wide range of physiological activities, but the regulation of ammonia-induced hepatocyte autophagy by PXR is not yet clear. In this study, the levels of down-regulated LC3B-II and up-regulated SQSTM1 were found in ammonia-induced PXR-overexpressing (PXR+) liver cells, but the opposite appeared in PXR-knockdown (PXR-) liver cells. Rifampicin, a PXR-activating agent, elicits a similar effect as PXR+ cells. The mechanism analysis reveals that the levels of the energy-sensitive molecule AMPKβ1 and phosphorylated AMPKβ1 (p-AMPKβ1) in PXR- cells are higher than those in control cells, whereas the levels of this molecule in PXR+ cells are lower than those in control cells. Two active sites that bind to P53 exist in -253 to -19 at the promoter region of AMPKβ1, and their mutation can reduce the transactivating effect of AMPKβ1 that P53 relies on. A protein interaction also exists between PXR and P53. These findings indicate that PXR is a factor interfering the formation of ammonia-induced hepatocyte autophagy, and its inhibitory effect is achieved when P53 downregulates the expression and activity of AMPKβ1. This conclusion provides an appropriate clinical explanation for hepatotoxicity caused by the inhibitory effect of PXR-activating agent on hepatocyte autophagy.

The impact of Mir-9 regulation in normal and malignant hematopoiesis

MicroRNA-9 (MiR-9) dysregulation has been observed in various cancers. Recently, MiR-9 is considered to have a part in hematopoiesis and hematologic malignancies. However, its importance in blood neoplasms is not yet well defined. Thus, this study was conducted in order to assess the significance of MiR-9 role in the development of hematologic neoplasia, prognosis, and treatment approaches. We have shown that a large number of MiR-9 targets (such as FOXOs, SIRT1, CCND1, ID2, CCNG1, Ets, and NFkB) play essential roles in leukemogenesis and that it is overexpressed in different leukemias. Our findings indicated MiR-9 downregulation in a majority of leukemias. However, its overexpression was reported in patients with dysregulated MiR-9 controlling factors (such as MLLr). Additionally, prognostic value of MiR-9 has been reported in some types of leukemia. This study generally emphasizes on the critical role of MiR-9 in hematologic malignancies as a prognostic factor and a therapeutic target.

Optimizing combination of liver-enriched transcription factors and nuclear receptors simultaneously favors ammonia and drug metabolism in liver cells

The HepG2 cell line is widely used in studying liver diseases because of its immortalization, but its clinical application is limited by its low expression of the urea synthesis key enzymes and cytochromes P450 (CYPs). On the basis of our previous work, we investigated the transcriptional regulation of arginase 1 (Arg1) and ornithine transcarbamylase (OTC) in HepG2 cells. We also screened for the optimal combination of liver enrichment transcription factors (LETFs) and xenobiotic nuclear receptors that can promote the expression of key urea synthases and five major CYPs in HepG2 cells. Thus, recombinant HepG2 cells were established. Results showed that C/EBPβ, not C/EBPα, could upregulate expression of Arg1 and PGC1α and HNF4α cooperatively regulate the expression of OTC. The two optimal combinations C/EBPβ+HNF4α+HNF6+PXR and C/EBPβ+HNF4α+HNF6+CAR were selected. Compared with the control cells, the recombinant HepG2 cells modified by the two optimal combinations exhibited enhanced ammonia metabolism and CYP enzyme activity. Moreover, the HepG2/(C/EBPβ+HNF4α+HNF6+PXR) cells more strongly reduced ammonia than any other combination tested in this study. The present work indicated that optimizing the combination of transcription factors will simultaneously promote hepatocyte ammonia metabolism and drug metabolism. The recombinant HepG2 liver cell line constructed by the optimal combination provided an improved alternative means for bioartificial liver applications and drug toxicity testing.

The activity of the carbamoyl phosphate synthase 1 promoter in human liver-derived cells is dependent on hepatocyte nuclear factor 3-beta

Carbamoyl phosphate synthase 1 (CPS1) is the rate‐limiting enzyme in the first step of the urea cycle and an indispensable enzyme in the metabolism of human liver. However, CPS1 epigenetic regulation involves promoter analysis and the role of liver‐enriched transcription factors (LETFs), which is not fully elucidated. In this work, the promoter region of hCPS1 gene was cloned, and its activity was investigated. An LETF, hepatocyte nuclear factor 3‐beta (HNF3β), was found to promote the transcriptional expression of CPS1 in liver‐derived cell lines. In addition, dual‐luciferase reporter assay shows that the essential binding sites of the HNF3β may exist in the oligonucleotide −70 nt to +73 nt. Two putative binding sites are available for HNF3β. Mutation analysis results show that the binding site 2 of HNF3β was effective, and the transcriptional activity of CPS1 promoter significantly decreased after mutation. Electrophoretic mobile shift assay (EMSA) and ChIP assay confirmed that HNF3β can interact with the binding site in the CPS1 promoter region of −70 nt to +73 nt promoter region in vivo and in vitro to regulate the transcription of CPS1. Moreover, HNF3β overexpression enhanced the transcription of CPS1 and consequently improved the mRNA and protein levels of CPS1, whereas the knockdown of HNF3β showed the opposite effects. Finally, urea production in cells was measured, and ammonia detoxification improved significantly in cells after transfection with HNF3β. HNF3β plays a vital role in regulation of CPS1 gene and could promote the metabolism of ammonia by regulating CPS1 expression.

Cellular Repressor of E1A-Stimulated Genes Is a Critical Determinant of Vascular Remodeling in Response to Angiotensin II

Objective—

Cellular repressor of E1A-stimulated genes (CREG) is a lysosomal glycoprotein implicated in maintaining vascular homeostasis. Here, we have hypothesized that CREG is a critical target of intervention for the prevention of hypertensive vascular remodeling.

Approach and Results—

CREG gene expression was significantly decreased accompanied by an upregulated expression of angiotensin II (Ang II) in remodeled vascular tissues of high salt–induced Dahl salt-sensitive rats and Ang II–induced mice. In particular, the downregulation of CREG gene was Ang II specific and independent from blood pressure. Prominent medial hypertrophy and vascular fibrosis in both thoracic aortas and mesenteric arteries were observed in CREG +/− mice infused with Ang II than in CREG +/+ mice, but blunted response in CREG +/+ mice received recombinant human CREG protein, suggesting that changes in CREG expression account for the different phenotype between genotypes. Within a tiled promoter array, E26 transformation-specific-1 binds to CREG promoter at high stringency with the stimulation of Ang II. Moreover, the Ang II–induced E26 transformation-specific-1 directly interacted with the CREG promoter (-1179 and -271 bp) and inhibited its transcription in vascular smooth muscle cells. Selective, pharmacological inhibition of E26 transformation-specific-1 led to restoration of CREG expression in aortas and rescue of experimental vascular remodeling by systemic administration of dominant negative E26 transformation-specific-1 membrane-permeable peptides.

Conclusions—

CREG is a novel mediator of vascular remodeling in response to Ang II and may be an attractive therapeutic target for prevention of vascular diseases.

Transcriptional regulation of the apolipoprotein F (ApoF) gene by ETS and C/EBPα in hepatoma cells

Apolipoprotein F (ApoF) inhibits cholesteryl ester transfer protein (CETP) activity and plays an important role in lipid metabolism. In the present study, the full-length human ApoF promoter was cloned, and the molecular mechanism of the regulation of ApoF was investigated. The ApoF promoter displayed higher activities in hepatoma cell lines, and the -198 nt to +79 nt promoter region contained the maximum promoter activity. In the promoter region of -198 nt to -2 nt there were four putative binding sites for transcription factors ETS-1/ETS-2 (named EBS-1 to EBS-4) and one for C/EBP. Mutation of EBS-2, EBS4 and the C/EBP binding site abolished the promoter activity, and ETS-1/ETS-2 and C/EBPα could interact with corresponding binding sites. In addition, overexpression of ETS-1/2 or C/EBPα enhanced, while dominant-negative mutants of ETS-1/2 and knockdown of C/EBPα decreased, ApoF promoter activities. ETS-1 and C/EBPα associated physically, and acted synergistically to activate ApoF transcription. These results demonstrated combined activation of the ApoF promoter by liver-enriched and ubiquitous transcription factors. Direct interactions between C/EBPα and ETS-1 were important for high liver-specific expression of ApoF.

Novel genes and pathways modulated by syndecan-1: implications for the proliferation and cell-cycle regulation of malignant mesothelioma cells

Malignant pleural mesothelioma is a highly malignant tumor, originating from mesothelial cells of the serous cavities. In mesothelioma the expression of syndecan-1 correlates to epithelioid morphology and inhibition of growth and migration. Our previous data suggest a complex role of syndecan-1 in mesothelioma cell proliferation although the exact underlying molecular mechanisms are not completely elucidated. The aim of this study is therefore to disclose critical genes and pathways affected by syndecan-1 in mesothelioma; in order to better understand its importance for tumor cell growth and proliferation. We modulated the expression of syndecan-1 in a human mesothelioma cell line via both overexpression and silencing, and followed the transcriptomic responses with microarray analysis. To project the transcriptome analysis on the full-dimensional picture of cellular regulation, we applied pathway analysis using Ingenuity Pathway Analysis (IPA) and a novel method of network enrichment analysis (NEA) which elucidated signaling relations between differentially expressed genes and pathways acting via various molecular mechanisms. Syndecan-1 overexpression had profound effects on genes involved in regulation of cell growth, cell cycle progression, adhesion, migration and extracellular matrix organization. In particular, expression of several growth factors, interleukins, and enzymes of importance for heparan sulfate sulfation pattern, extracellular matrix proteins and proteoglycans were significantly altered. Syndecan-1 silencing had less powerful effect on the transcriptome compared to overexpression, which can be explained by the already low initial syndecan-1 level of these cells. Nevertheless, 14 genes showed response to both up- and downregulation of syndecan-1. The "cytokine - cytokine-receptor interaction", the TGF-β, EGF, VEGF and ERK/MAPK pathways were enriched in both experimental settings. Most strikingly, nearly all analyzed pathways related to cell cycle were enriched after syndecan-1 silencing and depleted after syndecan-1 overexpression. Syndecan-1 regulates proliferation in a highly complex way, although the exact contribution of the altered pathways necessitates further functional studies.

Novel genes and pathways modulated by syndecan-1: implications for the proliferation and cell-cycle regulation of malignant mesothelioma cells

Malignant pleural mesothelioma is a highly malignant tumor, originating from mesothelial cells of the serous cavities. In mesothelioma the expression of syndecan-1 correlates to epithelioid morphology and inhibition of growth and migration. Our previous data suggest a complex role of syndecan-1 in mesothelioma cell proliferation although the exact underlying molecular mechanisms are not completely elucidated. The aim of this study is therefore to disclose critical genes and pathways affected by syndecan-1 in mesothelioma; in order to better understand its importance for tumor cell growth and proliferation. We modulated the expression of syndecan-1 in a human mesothelioma cell line via both overexpression and silencing, and followed the transcriptomic responses with microarray analysis. To project the transcriptome analysis on the full-dimensional picture of cellular regulation, we applied pathway analysis using Ingenuity Pathway Analysis (IPA) and a novel method of network enrichment analysis (NEA) which elucidated signaling relations between differentially expressed genes and pathways acting via various molecular mechanisms. Syndecan-1 overexpression had profound effects on genes involved in regulation of cell growth, cell cycle progression, adhesion, migration and extracellular matrix organization. In particular, expression of several growth factors, interleukins, and enzymes of importance for heparan sulfate sulfation pattern, extracellular matrix proteins and proteoglycans were significantly altered. Syndecan-1 silencing had less powerful effect on the transcriptome compared to overexpression, which can be explained by the already low initial syndecan-1 level of these cells. Nevertheless, 14 genes showed response to both up- and downregulation of syndecan-1. The "cytokine - cytokine-receptor interaction", the TGF-β, EGF, VEGF and ERK/MAPK pathways were enriched in both experimental settings. Most strikingly, nearly all analyzed pathways related to cell cycle were enriched after syndecan-1 silencing and depleted after syndecan-1 overexpression. Syndecan-1 regulates proliferation in a highly complex way, although the exact contribution of the altered pathways necessitates further functional studies.