Regulation of the human plasminogen activator inhibitor type 2 gene: cooperation of an upstream silencer and transactivator

SERPINB2, an Early Responsive Gene to Epigallocatechin Gallate, Inhibits Migration and Promotes Apoptosis in Esophageal Cancer Cells

Esophageal cancer is a lethal disease that frequently occurs in developing countries, the incidence of which could be declined by drinking EGCG-enriched drinks or food. SERPINB2, whose complex functions and regulations are not yet fully understood, are induced by multiple inflammatory molecules and anti-tumor agents. Here, we identify 2444 EGCG-regulated genes in esophageal cancer cells, including SERPINB2. EGCG treatment recruits NF-κB at the promoter and enhancers of SERPINB2 and activates gene transcription, which is repressed by NF-κB knockdown or inhibition. Loss of SERPINB2 leads to a faster migration rate and less expression of Caspase-3 in cancer cells. Our study demonstrates that SERPINB2 is a new tumor-suppressor gene involved in cell movement and apoptosis and could be a therapeutic target for esophageal cancer.

SERPINB2-its regulation and interplay with aryl hydrocarbon receptor

Despite many years of intensive investigation, real biological role of SERPINB2 is largely unknown. However, recent high throughput studies suggest its function in inflammation, influence on autoimmune disorders, and modulation of processes leading to carcinogenesis. SERPINB2 expression is acutely upregulated by many different stimuli, among others by aryl hydrocarbon receptor ligands. Mechanisms of regulation of SERPINB2 expression, involvement of the gene in processes leading to inflammation or carcinogenesis, and its interplay with aryl hydrocarbon receptor are subject of present review.

PAI-1 but Not PAI-2 Gene Deficiency Attenuates Ischemic Brain Injury After Experimental Stroke

After stroke, secondary brain damage is influenced by the extent of fibrin clot formation. This is counteracted by the endogenous fibrinolysis. Of major interest are the key players of the fibrinolytic plasminogen activator system including the urokinase plasminogen activator (uPA), the tissue-type plasminogen activator (tPA), and their endogenous inhibitors plasminogen activator inhibitor 1 (PAI-1) and PAI-2. The role of PAI-1 in brain injury is well established, whereas the importance of PAI-2 is unknown at present. The objectives of the present were twofold: first, to characterize the time-dependent cerebral mRNA expression of the plasminogen activator system (PAS) after brain ischemia and second, to investigate the impact of PAI-1 and PAI-2 on brain infarct volume using gene-deficient mice. Adult C57Bl/6J mice were subjected to unilateral transient middle cerebral artery occlusion (MCAO) followed by reperfusion for 3, 24, 72, or 120 h. Quantitative PCR revealed that brain mRNA expression levels of the PAS components, and particularly of PAI-1 (237-fold) and PAI-2 (19-fold), peaked at 24 h after stroke. Accordingly, PAI-1 plasma activity was strongly increased. Brain infarct volume in TTC (2,3,5-triphenyltetrazolium chloride)-stained brain sections was significantly smaller 24 h after MCAO in PAI-1-deficient mice (- 31%), but not in PAI-2-deficient mice (- 6%). Thus, endogenous upregulation of PAI-1, but not of PAI-2, might contribute to increased brain damage after acute ischemic stroke. The present study therefore shows that PAI-2 is induced by brain ischemia, but does not play an important or relevant role for secondary brain damage after brain injury.

microRNA-200c/141 upregulates SerpinB2 to promote breast cancer cell metastasis and reduce patient survival

The microRNA-200 (miR-200) family is associated with tumor metastasis and poor patient prognosis. We found that miR-200c/141 cluster overexpression upregulated SerpinB2 in the MDA-MB-231 triple-negative (TN) breast cancer cell line. We observed transcription factor (c-Jun, c-Fos, and FosB) upregulation, nuclear localization of c-Jun, and increased SerpinB2 promoter-directed chloramphenicol acetyltransferase activity in miR-200c/141 cluster-overexpressing cells relative to controls. Additionally, miR-124a and miR-26b, which directly target SepinB2, were downregulated compared to controls. In mouse xenograft models, miR-200c/141 cluster overexpression promoted lymph node and lung metastasis, and siRNA-mediated SerpinB2 knockdown decreased lung metastasis, suggesting that SerpinB2 mediates miR-200c/141-induced lung metastasis. We also explored the clinical significance of SerpinB2 protein status through analysis of primary breast tumor samples and The Cancer Genome Atlas (TCGA) data. High SerpinB2 levels were associated with reduced survival and increased lymph node metastasis in breast cancer patients. SerpinB2 was overexpressed in the TN breast cancer subtype as compared to the luminal subtype. The present study demonstrates that SerpinB2 promotes miR-200c/141 cluster overexpression-induced breast cancer cell metastasis, and SerpinB2 overexpression correlates with increased metastatic potential and unfavorable outcomes in breast cancer patients. SerpinB2 may be a useful biomarker for assessing metastasis risk in breast cancer patients.

Auranofin Suppresses Plasminogen Activator Inhibitor-2 Expression through Annexin A5 Induction in Human Prostate Cancer Cells

Auranofin has been developed as antirheumatic drugs, which is currently under clinical development for the treatment of chronic lymphocytic leukemia. Previous report showed that auranofin induced apoptosis by enhancement of annexin A5 expression in PC-3 cells. To understand the role of annexin A5 in auranofin-mediated apoptosis, we performed microarray data analysis to study annexin A5-controlled gene expression in annexin A5 knockdown PC-3 cells. Of differentially expressed genes, plasminogen activator inhibitor (PAI)-2 was increased by annexin A5 siRNA confirmed by qRT-PCR and western blot. Treatment with auranofin decreased PAI-2 and increased annexin A5 expression as well as promoting apoptosis. Furthermore, auranofin-induced apoptosis was recovered by annexin A5 siRNA but it was promoted by PAI-2 siRNA. Interestingly, knockdown of annexin A5 rescued PAI-2 expression suppressed by auranofin. Taken together, our study suggests that induction of annexin A5 by auranofin may enhance apoptosis through suppression of PAI-2 expression in PC-3 cells.

Regulation of the Extracellular SERPINA5 (Protein C Inhibitor) Penetration Through Cellular Membranes

It is generally accepted that the phospholipid bilayer of the cell membrane is impermeable for proteins and peptides and that these molecules require special mechanisms for their transport from the extra- to the intracellular space. Recently there is increasing evidence that certain proteins/peptides can also directly cross the phospholipid membrane. SERPINA5 (protein C inhibitor) is a secreted protease inhibitor with broad protease reactivity and wide tissue distribution. It binds glycosaminoglycans and certain phospoholipids, which can modulate its inhibitory activity. SERPINA5 has been shown to be internalized by platelets, granulocytes, HL-60 promyelocytic leukemia cells, and by Jurkat lymphoma cells. Once inside the cell it can translocate to the nucleus. There are several indications that SERPINA5 can directly cross the phospholipid bilayer of the cell membrane. In this review we will describe what is known so far about the conditions, as well as the cellular and molecular requirements for SERPINA5 translocation through the cell membrane and for its penetration of pure phospholipid vesicles.

Global identification of the genetic networks and cis-regulatory elements of the cold response in zebrafish

The transcriptional programs of ectothermic teleosts are directly influenced by water temperature. However, the cis- and trans-factors governing cold responses are not well characterized. We profiled transcriptional changes in eight zebrafish tissues exposed to mildly and severely cold temperatures using RNA-Seq. A total of 1943 differentially expressed genes (DEGs) were identified, from which 34 clusters representing distinct tissue and temperature response expression patterns were derived using the k-means fuzzy clustering algorithm. The promoter regions of the clustered DEGs that demonstrated strong co-regulation were analysed for enriched cis-regulatory elements with a motif discovery program, DREME. Seventeen motifs, ten known and seven novel, were identified, which covered 23% of the DEGs. Two motifs predicted to be the binding sites for the transcription factors Bcl6 and Jun, respectively, were chosen for experimental verification, and they demonstrated the expected cold-induced and cold-repressed patterns of gene regulation. Protein interaction modeling of the network components followed by experimental validation suggested that Jun physically interacts with Bcl6 and might be a hub factor that orchestrates the cold response in zebrafish. Thus, the methodology used and the regulatory networks uncovered in this study provide a foundation for exploring the mechanisms of cold adaptation in teleosts.

Genome-wide expression profiles of necrotizing enterocolitis versus spontaneous intestinal perforation in human intestinal tissues: dysregulation of functional pathways

OBJECTIVE

To provide a comprehensive database of gene regulation and compare differentially regulated molecular networks in human tissues of necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP).

BACKGROUND

Both NEC and SIP are devastating surgical emergencies associated with high morbidity and mortality in preterm infants. Their pathophysiology and molecular mechanisms remain unclear.

METHODS

Differential whole genome microarray analysis was performed on intestinal tissues collected from NEC (n = 15) and SIP (n = 12) infants and compared with tissues collected from surgical-control patients with noninflammatory intestinal conditions (n = 14). Validation of 52 target gene expressions was performed by quantitative polymerase chain reaction. Regulatory networks of significantly affected genes were constructed according to functional pathways.

RESULTS

Extensive and significant changes of gene expression were observed in NEC tissues, which comprised multiple pathways of angiogenesis, arginine metabolism, cell adhesion and chemotaxis, extracellular matrix remodeling, hypoxia and oxidative stress, inflammation, and muscle contraction. These dysregulated genes could be networked downstream of key receptors, TLR2, TLR4, and TREM1, and mediated via NF-κB, AP-1, and HIF1A transcription factor pathways, indicating predominant microbial and inflammatory involvement. In contrast, SIP tissues exhibited much milder and less diversified expressional changes, with target genes significantly associated with G-protein-mediated muscle contraction and extracellular matrix remodeling.

CONCLUSIONS

The molecular evidence suggests that NEC and SIP are likely 2 different diseases caused by distinct etiology and pathophysiology. This first comprehensive database on differential gene expression profiles of human NEC and SIP tissues could lead to development of disease-specific diagnostic and prognostic biomarkers and new therapeutic strategies for improving outcomes.

SerpinB2 mediated regulation of macrophage function during enteric infection

Host defense is an orchestrated response involving changes in the expression of receptors and release of mediators from both immune and structural cells. There is a growing recognition of the important role of proteolytic pathways for the protective immune response to enteric pathogens. Enteric nematode infection induces a type 2 immune response with polarization of macrophages toward the alternatively activated phenotype (M2). The Th2 cytokines, IL-4, and IL-13, induce a STAT6-dependent upregulation of the expression of the protease inhibitor, serpinB2, which protects macrophages from apoptosis. M2 are critical to worm clearance and a novel role for serpinB2 is its regulation of the chemokine, CCL2, which is necessary for monocyte and/or macrophage influx into small intestine during infection. There is a growing list of factors including immune (LPS, Th2 cytokines) as well as hormonal (gastrin, 5-HT) that are linked to increased expression of serpinB2. Thus, serpinB2 represents an immune regulated factor that has multiple roles in the intestinal mucosa.

Global Identification of EVI1 Target Genes in Acute Myeloid Leukemia

The ecotropic virus integration site 1 (EVI1) transcription factor is associated with human myeloid malignancy of poor prognosis and is overexpressed in 8-10% of adult AML and strikingly up to 27% of pediatric MLL-rearranged leukemias. For the first time, we report comprehensive genomewide EVI1 binding and whole transcriptome gene deregulation in leukemic cells using a combination of ChIP-Seq and RNA-Seq expression profiling. We found disruption of terminal myeloid differentiation and cell cycle regulation to be prominent in EVI-induced leukemogenesis. Specifically, we identified EVI1 directly binds to and downregulates the master myeloid differentiation gene Cebpe and several of its downstream gene targets critical for terminal myeloid differentiation. We also found EVI1 binds to and downregulates Serpinb2 as well as numerous genes involved in the Jak-Stat signaling pathway. Finally, we identified decreased expression of several ATP-dependent P2X purinoreceptors genes involved in apoptosis mechanisms. These findings provide a foundation for future study of potential therapeutic gene targets for EVI1-induced leukemia.

The transcription factor C/EBP-β mediates constitutive and LPS-inducible transcription of murine SerpinB2

SerpinB2 or plasminogen activator inhibitor type 2 (PAI-2) is highly induced in macrophages in response to inflammatory stimuli and is linked to the modulation of innate immunity, macrophage survival, and inhibition of plasminogen activators. Lipopolysaccharide (LPS), a potent bacterial endotoxin, can induce SerpinB2 expression via the toll-like receptor 4 (TLR4) by ∼1000-fold over a period of 24 hrs in murine macrophages. To map the LPS-regulated SerpinB2 promoter regions, we transfected reporter constructs driven by the ∼5 kb 5'-flanking region of the murine SerpinB2 gene and several deletion mutants into murine macrophages. In addition, we compared the DNA sequence of the murine 5′ flanking sequence with the sequence of the human gene for homologous functional regulatory elements and identified several regulatory cis-acting elements in the human SERPINB2 promoter conserved in the mouse. Mutation analyses revealed that a CCAAT enhancer binding (C/EBP) element, a cyclic AMP response element (CRE) and two activator protein 1 (AP-1) response elements in the murine SerpinB2 proximal promoter are essential for optimal LPS-inducibility. Electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrated that LPS induces the formation of C/EBP-β containing complexes with the SerpinB2 promoter. Importantly, both constitutive and LPS-induced SerpinB2 expression was severely abrogated in C/EBP-β-null mouse embryonic fibroblasts (MEFs) and primary C/EBP-β-deficient peritoneal macrophages. Together, these data provide new insight into C/EBP-β-dependent regulation of inflammation-associated SerpinB2 expression.