The ERK/MAPK pathway regulates the activity of the human tissue factor pathway inhibitor-2 promoter

Tissue factor pathway inhibitor-2 (TFPI-2)-an underappreciated partaker in cancer and metastasis

The coagulation system is known to play an important role in cancer development and metastasis, but the precise mechanisms by which it does so remain incompletely understood. With this in mind, we provide an updated overview of the effects of TFPI-2, a protease inhibitor, on cancer development and metastasis. TFPI-2 interacts with the thrombin cascade and also employs other mechanisms to suppress cancer growth and dissemination, which include extracellular matrix stabilization, promotion of caspase-mediated cell apoptosis, inhibition of angiogenesis and transduction of intracellular signals. Down-regulation of TFPI-2 expression is well documented in numerous types of neoplasms, mainly via promoter methylation. However, the exact role of TFPI-2 in cancer progression and possible approaches to up-regulate TFPI-2 expression warrant further studies. Strategies to reactivate TFPI-2 may represent a promising direction for future anticancer studies and therapy development.

LncRNA XR_001779380 Primes Epithelial Cells for IFN-γ-Mediated Gene Transcription and Facilitates Age-Dependent Intestinal Antimicrobial Defense

Interferon (IFN) signaling is key to mucosal immunity in the gastrointestinal tract, but cellular regulatory elements that determine interferon gamma (IFN-γ)-mediated antimicrobial defense in intestinal epithelial cells are not fully understood. We report here that a long noncoding RNA (lncRNA), GenBank accession no. XR_001779380, was increased in abundance in murine intestinal epithelial cells following infection by Cryptosporidium, an important opportunistic pathogen in AIDS patients and a common cause of diarrhea in young children. Expression of XR_001779380 in infected intestinal epithelial cells was triggered by TLR4/NF-κB/Cdc42 signaling and epithelial-specific transcription factor Elf3. XR_001779380 primed epithelial cells for IFN-γ-mediated gene transcription through facilitating Stat1/Swi/Snf-associated chromatin remodeling. Interactions between XR_001779380 and Prdm1, which is expressed in neonatal but not adult intestinal epithelium, attenuated Stat1/Swi/Snf-associated chromatin remodeling induced by IFN-γ, contributing to suppression of IFN-γ-mediated epithelial defense in neonatal intestine. Our data demonstrate that XR_001779380 is an important regulator in IFN-γ-mediated gene transcription and age-associated intestinal epithelial antimicrobial defense. IMPORTANCE Epithelial cells along the mucosal surface provide the front line of defense against luminal pathogen infection in the gastrointestinal tract. These epithelial cells represent an integral component of a highly regulated communication network that can transmit essential signals to cells in the underlying intestinal mucosa that, in turn, serve as targets of mucosal immune mediators. LncRNAs are recently identified long noncoding transcripts that can regulate gene transcription through their interactions with other effect molecules. In this study, we demonstrated that lncRNA XR_001779380 was upregulated in murine intestinal epithelial cells following infection by a mucosal protozoan parasite Cryptosporidium. Expression of XR_001779380 in infected cells primed host epithelial cells for IFN-γ-mediated gene transcription, relevant to age-dependent intestinal antimicrobial defense. Our data provide new mechanistic insights into how intestinal epithelial cells orchestrate intestinal mucosal defense against microbial infection.

m6A mRNA Methylation Regulates Epithelial Innate Antimicrobial Defense Against Cryptosporidial Infection

Increasing evidence supports that N6-methyladenosine (m⁶A) mRNA modification may play an important role in regulating immune responses. Intestinal epithelial cells orchestrate gastrointestinal mucosal innate defense to microbial infection, but underlying mechanisms are still not fully understood. In this study, we present data demonstrating significant alterations in the topology of host m⁶A mRNA methylome in intestinal epithelial cells following infection by Cryptosporidium parvum, a coccidian parasite that infects the gastrointestinal epithelium and causes a self-limited disease in immunocompetent individuals but a life-threatening diarrheal disease in AIDS patients. Altered m⁶A methylation in mRNAs in intestinal epithelial cells following C. parvum infection is associated with downregulation of alpha-ketoglutarate-dependent dioxygenase alkB homolog 5 and the fat mass and obesity-associated protein with the involvement of NF-кB signaling. Functionally, m⁶A methylation statuses influence intestinal epithelial innate defense against C. parvum infection. Specifically, expression levels of immune-related genes, such as the immunity-related GTPase family M member 2 and interferon gamma induced GTPase, are increased in infected cells with a decreased m⁶A mRNA methylation. Our data support that intestinal epithelial cells display significant alterations in the topology of their m⁶A mRNA methylome in response to C. parvum infection with the involvement of activation of the NF-кB signaling pathway, a process that modulates expression of specific immune-related genes and contributes to fine regulation of epithelial antimicrobial defense.

Polygenic analysis suggests the involvement of calcium signaling in executive function in schizophrenia patients

Cognitive deficits are increasingly recognized as a core dimension rather than a consequence of schizophrenia (SCZ). The previous evidence supports the hypothesis of shared genetic factors between SCZ and cognitive ability. The objective of this study was to test whether and to what extent the variation of disease-relevant neurocognitive function in a sample of SCZ patients from the previous clinical interventional studies can be explained by SCZ polygenic risk scores (PRSs) or by hypothesis-driven and biomedical PRSs. The previous studies have described associations of the SNAP25 gene with cognition in SCZ. Likewise, the enrichment of several calcium signaling-related gene sets has been reported by genome-wide association studies (GWAS) in SCZ. Hypothesis-driven PRSs were calculated on the basis of the SNAP-25 interactome and also for genes regulated by phorbol myristate acetate (PMA), an activator of the signal transduction of protein kinase C (PKC) enzymes. In a cohort of 127 SCZ patients who had completed a comprehensive neurocognitive test battery as part of the previous antipsychotic intervention studies, we investigated the association between neurocognitive dimensions and PRSs. The PRS for SCZ and SNAP-25-associated genes could not explain the variance of neurocognition in this cohort. At a p value threshold of 0.05, the PRS for PMA was able to explain 2% of the variance in executive function (p = 0.05, uncorrected). The correlation between the PRS for PMA-regulated genes and cognition can give hints for further patient-derived cellular assays. In conclusion, incorporating biological information into PRSs and other en masse genetic analyses may help to close the gap between genetic vulnerability and the biological processes underlying neuropsychiatric diseases such as SCZ.

Induction of a Long Noncoding RNA Transcript, NR_045064, Promotes Defense Gene Transcription and Facilitates Intestinal Epithelial Cell Responses against Cryptosporidium Infection

Cryptosporidium is an important opportunistic intestinal pathogen for immunocompromised individuals and a common cause of diarrhea in young children in developing countries. Gastrointestinal epithelial cells play a central role in activating and orchestrating host immune responses against Cryptosporidium infection, but underlying molecular mechanisms are not fully understood. We report in this paper that C. parvum infection causes significant alterations in long noncoding RNA (lncRNA) expression profiles in murine intestinal epithelial cells. Transcription of a panel of lncRNA genes, including NR_045064, in infected cells is controlled by the NF-κB signaling. Functionally, inhibition of NR_045064 induction increases parasite burden in intestinal epithelial cells. Induction of NR_045064 enhances the transcription of selected defense genes in host cells following C. parvum infection. Epigenetic histone modifications are involved in NR_045064-mediated transcription of associated defense genes in infected host cells. Moreover, the p300/MLL-associated chromatin remodeling is involved in NR_045064-mediated transcription of associated defense genes in intestinal epithelial cells following C. parvum infection. Expression of NR_045064 and associated genes is also identified in intestinal epithelium in C57BL/6J mice following phosphorothioate oligodeoxynucleotide or LPS stimulation. Our data demonstrate that lncRNAs, such as NR_045064, play a role in regulating epithelial defense against microbial infection.

Proangiogenic Effect of Metformin in Endothelial Cells Is via Upregulation of VEGFR1/2 and Their Signaling under Hyperglycemia-Hypoxia

Cardiovascular disease is the leading cause of morbidity/mortality worldwide. Metformin is the first therapy offering cardioprotection in type 2 diabetes and non-diabetic animals with unknown mechanism. We have shown that metformin improves angiogenesis via affecting expression of growth factors/angiogenic inhibitors in CD34⁺ cells under hyperglycemia-hypoxia. Now we studied the direct effect of physiological dose of metformin on human umbilical vein endothelial cells (HUVEC) under conditions mimicking hypoxia-hyperglycemia. HUVEC migration and apoptosis were studied after induction with euglycemia or hyperglycemia and/or CoCl₂ induced hypoxia in the presence or absence of metformin. HUVEC mRNA was assayed by whole transcript microarrays. Genes were confirmed by qRT-PCR, proteins by western blot, ELISA or flow cytometry. Metformin promoted HUVEC migration and inhibited apoptosis via upregulation of vascular endothelial growth factor (VEGF) receptors (VEGFR1/R2), fatty acid binding protein 4 (FABP4), ERK/mitogen-activated protein kinase signaling, chemokine ligand 8, lymphocyte antigen 96, Rho kinase 1 (ROCK1), matrix metalloproteinase 16 (MMP16) and tissue factor inhibitor-2 under hyperglycemia-chemical hypoxia. Therefore, metformin’s dual effect in hyperglycemia-chemical hypoxia is mediated by direct effect on VEGFR1/R2 leading to activation of cell migration through MMP16 and ROCK1 upregulation, and inhibition of apoptosis by increase in phospho-ERK1/2 and FABP4, components of VEGF signaling cascades.

Xenoestrogen regulation of ERα/ERβ balance in hormone-associated cancers

The hormone 17β-estradiol (E2) contributes to body homeostasis maintenance by regulating many different physiological functions in both male and female organs. E2 actions in reproductive and non-reproductive tissues rely on a complex net of nuclear and extra-nuclear signal transduction pathways triggered by at least two estrogen receptor subtypes (ERα and ERβ). Consequently, the de-regulation of E2:ER signaling contributes to the pathogenesis of many diseases including cancer. Among other factors, the ERα/ERβ ratio is considered one of the pivotal mechanisms at the root of E2 action in cancer progression. Remarkably, several natural or synthetic exogenous chemicals, collectively called xenoestrogens, bind to ERs and interfere with their signals and intracellular functions. In this review, the molecular mechanism(s) through which xenoestrogens influence ERα and ERβ intracellular concentrations and the consequences of this influence on E2-related cancer will be discussed.

LincRNA-Cox2 modulates TNF-α-induced transcription of Il12b gene in intestinal epithelial cells through regulation of Mi-2/NuRD-mediated epigenetic histone modifications

Long intergenic noncoding RNAs (lincRNAs) can regulate the transcription of inflammatory genes and thus may represent a new group of inflammatory mediators with a potential pathogenic role in inflammatory diseases. Here, our genome-wide transcriptomic data show that TNF-α stimulation caused up-regulation of 171 lincRNAs and down-regulation of 196 lincRNAs in murine intestinal epithelial cells in culture. One of the up-regulated lincRNAs, lincRNA-Cox2, is an early-responsive lincRNA induced by TNF-α through activation of the NF-ĸB signaling pathway. Knockdown of lincRNA-Cox2 resulted in reprogramming of the gene expression profile in intestinal epithelial cells in response to TNF-α stimulation. Specifically, lincRNA-Cox2 silencing significantly (P < 0.05) enhanced the transcription of Il12b, a secondary late-responsive gene induced by TNF-α. Mechanistically, lincRNA-Cox2 promoted the recruitment of the Mi-2/nucleosome remodeling and deacetylase (Mi-2/NuRD) repressor complex to the Il12b promoter region. Recruitment of the Mi-2/NuRD complex was associated with decreased H3K27 acetylation and increased H3K27 dimethylation at the Il12b promoter region, which might contribute to Il12b trans-suppression by lincRNA-Cox2. Thus, our data demonstrate a novel mechanism of epigenetic modulation by lincRNA-Cox2 on Il12b transcription, supporting an important role for lincRNAs in the regulation of intestinal epithelial inflammatory responses.

Ikaros mediates the DNA methylation-independent silencing of MCJ/DNAJC15 gene expression in macrophages

MCJ (DNAJC15) is a mitochondrial protein that regulates the mitochondrial metabolic status of macrophages and their response to inflammatory stimuli. CpG island methylation in cancer cells constitutes the only mechanism identified for the regulation of MCJ gene expression. However, whether DNA methylation or transcriptional regulation mechanisms are involved in the physiological control of this gene expression in non-tumor cells remains unknown. We now demonstrate a mechanism of regulation of MCJ expression that is independent of DNA methylation. IFNγ, a protective cytokine against cardiac inflammation during Lyme borreliosis, represses MCJ transcription in macrophages. The transcriptional regulator, Ikaros, binds to the MCJ promoter in a Casein kinase II-dependent manner, and mediates the repression of MCJ expression. These results identify the MCJ gene as a transcriptional target of IFNγ and provide evidence of the dynamic adaptation of normal tissues to changes in the environment as a way to adapt metabolically to new conditions.

P14ARF suppresses tumor-induced thrombosis by regulating the tissue factor pathway

How necrotic areas develop in tumors is incompletely understood but can impact progression. Recent findings suggest that the formation of vascular microthrombi contributes to tumor necrosis, prompting investigation of coagulation cascades. Here, we report that loss of tumor suppressor P14ARF can contribute to activating the clotting cascade in glioblastoma. P14ARF transcriptionally upregulated TFPI2, a Kunitz-type serine protease in the tissue factor pathway that inhibits the initiation of thrombosis reactions. P14ARF activation in tumor cells delayed their ability to activate plasma clotting. Mechanistically, P14ARF activated the TFPI2 promoter in a p53-independent manner that relied upon c-JUN, SP1, and JNK activity. Taken together, our results identify the critical signaling pathways activated by P14ARF to prevent vascular microthrombosis triggered by glioma cells. Stimulation of this pathway might be used as a therapeutic strategy to reduce aggressive phenotypes associated with necrotic tumors, including glioblastoma.

Osmotic stress changes the expression and subcellular localization of the Batten disease protein CLN3

Juvenile CLN3 disease (formerly known as juvenile neuronal ceroid lipofuscinosis) is a fatal childhood neurodegenerative disorder caused by mutations in the CLN3 gene. CLN3 encodes a putative lysosomal transmembrane protein with unknown function. Previous cell culture studies using CLN3-overexpressing vectors and/or anti-CLN3 antibodies with questionable specificity have also localized CLN3 in cellular structures other than lysosomes. Osmoregulation of the mouse Cln3 mRNA level in kidney cells was recently reported. To clarify the subcellular localization of the CLN3 protein and to investigate if human CLN3 expression and localization is affected by osmotic changes we generated a stably transfected BHK (baby hamster kidney) cell line that expresses a moderate level of myc-tagged human CLN3 under the control of the human ubiquitin C promoter. Hyperosmolarity (800 mOsm), achieved by either NaCl/urea or sucrose, dramatically increased the mRNA and protein levels of CLN3 as determined by quantitative real-time PCR and Western blotting. Under isotonic conditions (300 mOsm), human CLN3 was found in a punctate vesicular pattern surrounding the nucleus with prominent Golgi and lysosomal localizations. CLN3-positive early endosomes, late endosomes and cholesterol/sphingolipid-enriched plasma membrane microdomain caveolae were also observed. Increasing the osmolarity of the culture medium to 800 mOsm extended CLN3 distribution away from the perinuclear region and enhanced the lysosomal localization of CLN3. Our results reveal that CLN3 has multiple subcellular localizations within the cell, which, together with its expression, prominently change following osmotic stress. These data suggest that CLN3 is involved in the response and adaptation to cellular stress.

Promoter of TFPI-2 is hypermethylated in Chinese pediatric acute myeloid leukemia

Human tissue factor pathway inhibitor-2 (TFPI-2) has been implicated as a metastasis-associated gene in many types of tumors. In this study, we investigated whether TFPI-2 was inactivated epigenetically in pediatric acute myeloid leukemia (AML). Methylation status was investigated by methylation-specific polymerase chain reaction and bisulfate genomic sequencing. TFPI-2 was aberrantly methylated in 50% (3/6) of AML cell lines. Aberrant methylation of TFPI-2 promoter was detected in 71.6% (48/67) of the Chinese pediatric AML patients. TFPI-2 transcript was significantly lower in AML group compared with controls (3.44 vs. 32.8, P<0.001). Patients with methylated TFPI-2 gene had significantly lower TFPI-2 transcript than those patients without methylated TFPI-2 (P=0.04). Promoter hypermethylation of TFPI-2 is frequent and specific event in pediatric AML.

Invasive markers identified by gene expression profiling in pancreatic cancer

BACKGROUND

Molecular profiling has proven utility as a diagnostic and predictive tool in clinical oncology. However, a clinically relevant gene expression profile in pancreatic cancer remains elusive.

METHODS

Primary and metastatic pancreatic cancer cell lines (BxPC-3 and AsPC-1), were stimulated with phorbol-12-myristate 13-acetate (PMA), a known inducer of cell invasion. Affymetrix gene expression microarray analysis was performed, comparing gene expression to unstimulated controls. Differential expression was identified using ArrayAssist, and confirmed using quantitative real-time PCR. Bioinformatic analysis was performed using Pathway Studio and GOstat. The derived gene expression was further validated in fresh frozen pancreatic tumour samples. The ability of the derived 3 gene expression markersto differentiate between pancreatic adenocarcinoma (PDAC) and other neoplasms, and its association with clinicopathological variables was examined.

RESULTS

PMA-induced significant changes in cell line gene expression, from which distinctive 3 potential invasive markers were derived. Expression of these genes, uPA, MMP-1 and IL1-R1 was confirmed in human pancreatic tumours, and was found to differentiate PDAC from other pancreatic neoplasms. The expression of IL1-R1 in PDAC is a novel finding. We found that the expression of MMP-1 was associated with high-grade PDAC (p = 0.035, Wilcoxon rank sum).

CONCLUSION

We have identified three potential invasive markers, uPA, MMP-1 and IL1-R1, whose gene expression may differentiate PDAC from other pancreatic neoplasms, and potentially reflect a more invasive phenotype.

Glucagon counteracts interleukin-6-dependent gene expression by redundant action of Epac and PKA

Inflammation is the biological response to injurious stimuli. In the initial phase of the inflammatory process, interleukin-6 (IL-6) is the main inducer of acute phase protein expression in the liver. A prolonged acute phase response is characterised by a disturbed glucose homeostasis and elevated levels of IL-6, insulin, and counterregulatory hormones such as glucagon. Several studies deal with the impact of IL-6 on glucagon-dependent gene expression. In contrast, only very little is known about the influence of G-protein-coupled receptors on IL-6 signalling. Therefore, the aim of this study is to elucidate the regulation of IL-6-induced gene expression by glucagon. We could reveal a novel mechanism of negative regulation of IL-6-induced MAP kinase activation by glucagon in primary murine hepatocytes. IL-6-dependent induction of the ERK-dependent target geneTfpi2, coding for a Kunitz-type serine protease inhibitor, was strongly down-regulated by glucagon treatment. Studying the underlying mechanism revealed a redundant action of the signalling molecules exchange protein activated by cyclic AMP (Epac) and protein kinase A. The metabolic hormone glucagon interferes in IL-6-induced gene expression. This observation is indicative for a regulatory role of G-protein-coupled receptors in the IL-6-dependent inflammatory response.

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

AIM

To investigate the role of transcription factor c-Ets1 in cyclin D3 expression and its effects on the proliferation of umbilical cord hematopoietic cells.

METHODS

Cyclin D3 promoter deletion constructs were generated and transfected into CD34(+) cells. Dual luciferase reporter assays and TFSEARCH software were used to identify negative regulatory domains and to predict putative transcription factors involved in cyclin D3 downregulation. Expression of c-Ets1 in CD34(+) cells was detected using electrophoretic mobility shift and super shift assays. Point mutants of c-Ets1 binding sites were constructed. The wild-type c-Ets1 and the mutant promoter constructs were co-transfected into CD34(+) cells to determine the promoter activity. The impact of c-Ets1 expression on the proliferation of CD34(+) cells was assessed using MTT assay.

RESULTS

Nine cyclin D3 promoter deletion constructs were generated. A negative regulatory domain containing c-Ets1 binding sites was identified between -439 bp and -362 bp. Transfection of the promoter deletion constructs containing mutant c-Ets1 binding sites enhanced cyclin D3 promoter activity. However, the opposite results were observed when CD34(+) cells were co-transfected with wildtype c-Ets1 and its promoter deletion constructs. The overexpression of c-Ets1 could suppress cyclin D3 mRNA and protein levels. In addition, it inhibits the proliferation of CD34(+) cells.

CONCLUSION

c-Ets1 functions as a negative transcription factor, down-regulating the expression of cyclin D3, which leads to inhibition of CD34(+) cell proliferation.

PMA up-regulates the transcription of Axl by AP-1 transcription factor binding to TRE sequences via the MAPK cascade in leukaemia cells

BACKGROUND

Axl is a receptor tyrosine kinase promoting anti-apoptosis, invasion and mitogenesis, and is highly expressed in different solid cancers. Axl basal transcriptional activity is driven by Sp1/Sp3, and overexpression of MZF-1 (myeloid zinc-finger 1) induces Axl transcription and gene expression. Furthermore, Axl expression is epigenetically controlled by CpG hypermethylation; however, little is known about inducible Axl gene expression and Axl regulation in haematopoetic malignancies.

RESULTS

In the present study, we studied Axl transcriptional regulation under PMA-stimulated conditions in leukaemia cells. Luciferase analysis with sequential 5'-deletion constructs revealed that the -660/-580 region of the Axl promoter is indispensable for induced promoter activity under PMA stimulation. This region includes AP-1 (activator protein 1)/CREB [CRE (cAMP-response-element)-binding protein] motifs, five times partially overlapping TGCGTG repeats and multiple GT repeats. Mutational, supershift and ChIP (chromatin immunoprecipitation) analysis determined that AP-1 family members bind to AP-1 motifs and to the 5 × TGCGTG overlapping repeats, thus transactivating Axl promoter activity. Furthermore, specific inhibitors of PKC (protein kinase C), ERK1/2 (extracellular-signal-regulated kinase 1/2) and p38 reduced Axl expression. Additionally, mithramycin treatment abolished constitutive and PMA-induced Axl expression.

CONCLUSIONS

Taken together the results of the present study suggest that PMA-induced Axl gene expression in leukaemia cells is mediated by AP-1 motifs and 5 × TGCGTG repeats within the promoter region -660/-580, and through the PKC/ERK1/2/AP-1 or PKC/p-38/AP-1 signalling axis.

Binding of NF-kappaB p65 subunit to the promoter elements is involved in LPS-induced transactivation of miRNA genes in human biliary epithelial cells

The majority of human miRNA genes is transcribed by polymerase II and can be classified as class II genes similar to protein-coding genes. Whereas current research on miRNAs has focused on the physiological and pathological functions, the molecular mechanisms underlying their transcriptional regulation are largely unknown. We recently reported that lipopolysaccharide (LPS) alters mature miRNA expression profile in human biliary epithelial cells. In this study, we tested the role of transcription factor NF-κB in LPS-induced transcription of select miRNA genes. Of the majority of LPS-up-regulated mature miRNAs in cultured human biliary epithelial cells, potential NF-κB binding sites were identified in the putative promoter elements of their corresponding genes. Inhibition of NF-κB activation by SC-514, an IKK2 inhibitor, blocked LPS-induced up-regulation of a subset of pri-miRNAs, including pri-miR-17-92, pri-miR-125b-1, pri-miR-21, pri-miR-23b-27b-24-1, pri-miR-30b, pri-miR-130a and pri-miR-29a. Moreover, direct binding of NF-κB p65 subunit to the promoter elements of mir-17-92, mir-125b-1, mir-21, mir-23b-27b-24-1, mir-30b and mir-130a genes was identified by chromatin immunoprecipitation analysis and confirmed by the luciferase reporter assay. Thus, a subset of miRNA genes is regulated in human biliary epithelial cells through NF-κB activation induced by LPS, suggesting a role of the NF-κB pathway in the transcriptional regulation of miRNA genes.

Induction of ANGPTL4 expression in human airway smooth muscle cells by PMA through activation of PKC and MAPK pathways

In this study, we demonstrate that protein kinase C (PKC) activators, including phorbol-12-myristate-13-acetate (PMA), 1,2-dioctanoyl-sn-glycerol (DOG), and platelet-derived growth factor alpha are potent inducers of angiopoietin-like protein 4 (ANGPTL4) expression in several normal lung cell types and carcinoma cell lines. In human airway smooth muscle (HASM) cells induction of ANGPTL4 expression is observed as early as 2 h after the addition of PMA. PMA also increases the level of ANGPTL4 protein released in the medium. PKC inhibitors Ro31-8820 and Gö6983 greatly inhibit the induction of ANGPTL4 mRNA by PMA suggesting that this up-regulation involves activation of PKC. Knockdown of several PKCs by corresponding siRNAs suggest a role for PKCalpha. PMA does not activate MAPK p38 and p38 inhibitors have little effect on the induction of ANGPTL4 indicating that p38 is not involved in the regulation of ANGPTL4 by PMA. In contrast, treatment of HASM by PMA induces phosphorylation and activation of Ra, MEK1/2, ERK1/2, JNK, Elk-1, and c-Jun. The Ras inhibitor manumycin A, the MEK1/2 inhibitor U0126, and the JNK inhibitor SP600125, greatly reduce the increase in ANGPTL4 expression by PMA. Knockdown of MEK1/2 and JNK1/2 expression by corresponding siRNAs inhibits the induction of ANGPTL4. Our observations suggest that the induction of ANGPTL4 by PMA in HASM involves the activation of PKC, ERK, and JNK pathways. This induction may play a role in tissue remodeling during lung injury and be implicated in several lung pathologies.

NF-kappaB p65-dependent transactivation of miRNA genes following Cryptosporidium parvum infection stimulates epithelial cell immune responses

Cryptosporidium parvum is a protozoan parasite that infects the gastrointestinal epithelium and causes diarrheal disease worldwide. Innate epithelial immune responses are key mediators of the host's defense to C. parvum. MicroRNAs (miRNAs) regulate gene expression at the posttranscriptional level and are involved in regulation of both innate and adaptive immune responses. Using an in vitro model of human cryptosporidiosis, we analyzed C. parvum-induced miRNA expression in biliary epithelial cells (i.e., cholangiocytes). Our results demonstrated differential alterations in the mature miRNA expression profile in cholangiocytes following C. parvum infection or lipopolysaccharide stimulation. Database analysis of C. parvum-upregulated miRNAs revealed potential NF-κB binding sites in the promoter elements of a subset of miRNA genes. We demonstrated that mir-125b-1, mir-21, mir-30b, and mir-23b-27b-24-1 cluster genes were transactivated through promoter binding of the NF-κB p65 subunit following C. parvum infection. In contrast, C. parvum transactivated mir-30c and mir-16 genes in cholangiocytes in a p65-independent manner. Importantly, functional inhibition of selected p65-dependent miRNAs in cholangiocytes increased C. parvum burden. Thus, we have identified a panel of miRNAs regulated through promoter binding of the NF-κB p65 subunit in human cholangiocytes in response to C. parvum infection, a process that may be relevant to the regulation of epithelial anti-microbial defense in general.

MicroRNAs (miRNAs) are newly identified small non-coding RNAs that regulate gene expression at the posttranscriptional level. While much of our understanding of the cellular processes modulated by miRNAs has come from studies on development and tumorigenesis, the role of miRNAs in immune responses is now being gradually uncovered. Nevertheless, whether miRNA-mediated posttranscriptional gene regulation is involved in the fine-tuning of epithelial cell immune responses against pathogen infection remains undefined. Cryptosporidium parvum is a protozoan parasite that infects gastrointestinal epithelium. TLR/NF-κB-mediated innate immune responses by epithelial cells are critical to the host's defense to infection. Using an in vitro model of human cryptosporidiosis, we show here differential alterations in the miRNA expression profile in biliary epithelial cells following C. parvum infection. Promoter binding of NF-κB p65 subunit accounts for the upregulation of a panel of miRNA genes in cells infected by C. parvum. Importantly, functional inhibition of several NF-κB p65-dependent miRNAs in epithelial cells increases C. parvum infection burden. Our findings suggest that host epithelial cells activate NF-κB signaling to regulate miRNA expression in response to C. parvum infection. Moreover, NF-κB-mediated miRNA expression is involved in epithelial anti-microbial defense. Our study provides new insights into epithelial cell immunoregulation.

Molecular mechanisms underlying the pro-inflammatory synergistic effect of tumor necrosis factor alpha and interferon gamma in human microvascular endothelium

Tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) are among the most potent cytokines involved in orchestrating the inflammation response. The molecular mechanisms implicated in the synergism between cytokines are still poorly characterized. We demonstrate that both cytokines dose-dependently stimulate IFNgamma-inducible-protein-of-10-kDa (IP-10) secretion in human microvascular endothelial cells (HMEC-1), showing a potent synergism which is not restricted to IP-10, but is also evident for monokine-induced-by-IFNgamma (MIG) and IL-6 secretion. Immunofluorescence analysis reveals that TNFalpha and IFNgamma converge on a rapid phosphorylation of ERK, which however results in a different subcellular compartmentalization of the activated enzyme in response to the two cytokines. Differences in the subcellular recruitment of ERK in response to IFNgamma and TNFalpha are responsible for generating different ERK downstream signaling, which can thus synergize on the secretion of IP-10 as well as of other cytokines/chemokines. The importance of ERK activation in mediating the synergism of the two cytokines is further confirmed by the inhibitory effect of the anti-diabetic drug rosiglitazone and ERK blockers on IP-10, MIG and IL-6 secretion. A further mechanism of synergism involving the reciprocal upregulation of TNFalpha-RII and of IFNgamma-R, in response to IFNgamma and TNFalpha, respectively, was revealed by flow cytometry and quantitative real time RT-PCR analysis.

Frequent decreased expression of candidate tumor suppressor gene, DEC1, and its anchorage-independent growth properties and impact on global gene expression in esophageal carcinoma

Previous studies showed that expression of the novel candidate tumor suppressor gene, DEC1 (Deleted in Esophageal Cancer 1), is reduced in esophageal carcinoma and suppresses cancer cell growth in vitro and tumor growth in vivo in nude mice. This study shows that DEC1 gene expression was downregulated in 100% of 16 esophageal squamous cell carcinoma (ESCC) cell lines and 52 and 45%, respectively, of esophageal tumor specimens from Hong Kong and a high-risk ESCC region of Henan, China. Using epitope tagging, the DEC1 protein was localized to both the cytoplasm and nucleus of the cell. In 3D Matrigel culture, no significant difference in colony numbers formed was observed for DEC1 stable transfectants, as compared to vector-alone transfectant controls. However, significantly smaller colony sizes were observed for the DEC1 transfectants. In in vitro cell migration, invasion and soft agar assays of DEC1 transfectants, only the soft agar assay showed statistically significant differences in colony numbers with the vector-alone controls, indicating that DEC1 may be involved in anchorage-independent cell growth. In addition, the global gene expression affected by DEC1 in tumor-suppressive stable transfectants was investigated using cDNA oligonucleotide microarray hybridization. Three candidate genes, TFPI-2, GDF15 and DUSP6, were identified through this approach; they are downregulated in tumor segregants of DEC1 stable transfectants, ESCC cell lines and esophageal tumors and have a potential role in tumor growth and progression. These studies show that DEC1 is involved in esophageal cancer development and help elucidate its functional role in tumor development.

Tissue factor pathway inhibitor-2 was repressed by CpG hypermethylation through inhibition of KLF6 binding in highly invasive breast cancer cells

Background

Tissue factor pathway inhibitor-2 (TFPI-2) is a matrix-associated Kunitz inhibitor that inhibits plasmin and trypsin-mediated activation of zymogen matrix metalloproteinases involved in tumor progression, invasion and metastasis. Here, we have investigated the mechanism of DNA methylation on the repression of TFPI-2 in breast cancer cell lines.

Results

We found that both protein and mRNA of TFPI-2 could not be detected in highly invasive breast cancer cell line MDA-MB-435. To further investigate the mechanism of TFPI-2 repression in breast cancer cells, 1.5 Kb TFPI-2 promoter was cloned, and several genetic variations were detected, but the promoter luciferase activities were not affected by the point mutation in the promoter region and the phenomena was further supported by deleted mutation. Scan mutation and informatics analysis identified a potential KLF6 binding site in TFPI-2 promoter. It was revealed, by bisulfite modified sequence, that the CpG island in TFPI-2 promoter region was hypermethylated in MDA-MB-435. Finally, using EMSA and ChIP assay, we demonstrated that the CpG methylation in the binding site of KLF-6 diminished the binding of KLF6 to TFPI-2 promoter.

Conclusion

In this study, we found that the CpG islands in TFPI-2 promoter was hypermethylated in highly invasive breast cancer cell line, and DNA methylation in the entire promoter region caused TFPI-2 repression by inducing inactive chromatin structure and decreasing KLF6 binding to its DNA binding sequence.

Silencing of tissue factor pathway inhibitor-2 gene in malignant melanomas

To identify tumor-suppressor genes inactivated by aberrant methylation of promoter CpG islands (CGIs) in human malignant melanomas, genes upregulated by treatment of cells with a demethylating agent, 5-aza-2'-deoxycytidine (5-aza-dC), were searched for using oligonucleotide microarrays in melanoma cell lines, HMV-I, MeWo and WM-115. Seventy-nine known genes with CGIs were identified as being upregulated (>or=16-fold), and 18 of them had methylation of their putative promoter CGIs in 1 or more of 8 melanoma cell lines. Among the 18 genes, TFPI-2, which is involved in repression of the invasive potential of malignant melanomas, was further analyzed. Its expression was repressed in a melanoma cell line with its complete methylation, and was restored by 5-aza-dC treatment. It was unmethylated in cultured neonatal normal epidermal melanocyte, and was induced by ultraviolet B. In surgical melanoma specimens, TFPI-2 methylation was detected in 5 of 17 metastatic site specimens (29%), while it was not detected in 20 primary site specimens (0%) (p=0.009). By immunohistochemistry, the 5 specimens with promoter methylation lacked immunoreactivity for TFPI-2. The results showed that TFPI-2 is silenced in human malignant melanomas by methylation of its promoter CGI and suggested that its silencing is involved in melanoma metastasis.

Transcriptional Control of the HumanHigh Mobility Group A1Gene: Basal and Oncogenic Ras-Regulated Expression

Several studies have already shown that the high mobility group A1 (HMGA1) gene is up-regulated in most common types of cancer and immortalized tissue culture cell lines. HMGA1 expression is also much higher during embryonic development than in adult life. The elevated expression of HMGA1 in cancer thus likely occurs through oncofetal transcriptional mechanisms, which to date have not been well characterized. In the present study, we have cloned and functionally analyzed the TATA-less 5'-flanking regulatory region of human HMGA1. We identified two proximal regulatory regions that are important for basal transcription and in which specificity protein 1 (SP1) and activator protein 1 (AP1) transcription factors seem to be the regulating elements. In addition, we showed that the HMGA1 promoter is strongly inducible by oncogenic Ras, via a distal regulatory region. An AP1 site and three SP1-like sites are responsible for this inducible activity. An even more convincing finding for a role of oncogenic Ras in the regulation of HMGA1 in cancers is the discovery that HMGA1 up-regulation in the HCT116 colon cancer cell line is abolished when the mutated Ras allele is removed from these cells. Our data constitute the first extensive study of the regulation of basal and Ras-induced human HMGA1 gene expression and suggest that the elevated expression of HMGA1 in cancer cells requires, among others, a complex cooperation between SP1 family members and AP1 factors by the activation of Ras GTPase signaling.

Tissue Factor Pathway Inhibitor-2 Is Upregulated by Vascular Endothelial Growth Factor and Suppresses Growth Factor-Induced Proliferation of Endothelial Cells

Objective— The purpose of this study is to investigate the expression and regulation of type-2 tissue factor pathway inhibitor (TFPI-2) in endothelial cells, as well as the regulation of human endothelial cell (EC) function by TFPI-2.

Methods and Results— Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that vascular endothelial growth factor (VEGF) induced both time- and dose-dependent increase in TFPI-2 mRNA and protein expression in endothelial cells. TFPI-2 mRNA expression was also significantly upregulated by IL-1β, and modestly increased by both tumor necrosis factor (TNF)-α and fibroblast growth factor (FGF)-2, but not placental growth factor (PlGF). VEGF upregulation of TFPI-2 was dramatically reduced by inhibition of the MEK pathway. Administration of TFPI-2 protein suppressed both VEGF and FGF-2 stimulation of EC proliferation in a dose-dependent manner. A recombinant preparation of the first Kunitz-type domain of TFPI-2 (KD1) did not suppress growth factor stimulation of EC proliferation, suggesting a mechanism distinct from the proteinase inhibitory activity of TFPI-2. Exogenously added TFPI-2 protein suppressed VEGF-induced EC migration in 2 different assays. Recombinant wt-KD1 or the R24K mutant of KD1, but not the R24Q mutant, dramatically suppressed VEGF-induced EC migration. TFPI-2 protein, but not recombinant KD1, blocked VEGF-induced activation of both Akt and ERK1/2 in ECs. At higher doses, TFPI-2 protein blocked VEGFR2 activation.

Conclusion— Our data suggest that VEGF-upregulation of TFPI-2 expression in endothelial cells may represent a mechanism for negative feedback regulation and modulation of its pro-angiogenic action on endothelial cells. TFPI-2, or derivatives of TFPI-2, may be novel therapeutics for treatment of angiogenic disease processes.

DJ-1, a cancer- and Parkinson's disease-associated protein, stabilizes the antioxidant transcriptional master regulator Nrf2

DJ-1/PARK7, a cancer- and Parkinson's disease (PD)-associated protein, protects cells from toxic stresses. However, the functional basis of this protection has remained elusive. We found that loss of DJ-1 leads to deficits in NQO1 [NAD(P)H quinone oxidoreductase 1], a detoxification enzyme. This deficit is attributed to a loss of Nrf2 (nuclear factor erythroid 2-related factor), a master regulator of antioxidant transcriptional responses. DJ-1 stabilizes Nrf2 by preventing association with its inhibitor protein, Keap1, and Nrf2's subsequent ubiquitination. Without intact DJ-1, Nrf2 protein is unstable, and transcriptional responses are thereby decreased both basally and after induction. This effect of DJ-1 on Nrf2 is present in both transformed lines and primary cells across human and mouse species. DJ-1's effect on Nrf2 and subsequent effects on antioxidant responses may explain how DJ-1 affects the etiology of both cancer and PD, which are seemingly disparate disorders. Furthermore, this DJ-1/Nrf2 functional axis presents a therapeutic target in cancer treatment and justifies DJ-1 as a tumor biomarker.

Poxviral regulation of the host NF-kappaB response: the vaccinia virus M2L protein inhibits induction of NF-kappaB activation via an ERK2 pathway in virus-infected human embryonic kidney cells

Exposure of eukaryotic cells to viruses will activate the host NF-kappaB transcription factor, resulting in proinflammatory and immune protein production. Vaccinia virus (VV), the prototypic orthopoxvirus, expresses products that inhibit this antiviral event. To identify novel mechanisms responsible for this effect, we made use of a VV deletion mutant (MVA) that stimulates NF-kappaBeta activation in infected 293T cells. In this virus-host system, the extents of NF-kappaBeta-regulated gene expression and nuclear translocation were reduced in the presence of either PD 98059 or U0126, two compounds capable of blocking ERK1 and ERK2 phosphorylation. A similar repression was also observed in cells that contained a dominant, nonactive form of ERK2 but not in cells where ERK1 phosphorylation was inhibited via overexpression of a dominant-negative mutant MEK1 protein. Presumably, proteins expressed from a wild-type VV that block ERK2 activity would also inhibit MVA-induced NF-kappaB activation. Indeed, the expression of one such open reading frame, M2L, supported this prediction. First, ectopic M2L expression hampered ERK2 phosphorylation induced by exposure to phorbol myristate acetate. Second, viral M2L expression via infection of cells with a recombinant MVA construct that stably expressed M2L decreased the phosphorylation of ERK2 compared to that in cells infected with the parental MVA strain. Finally, the recombinant M2L-expressing virus restored the "wild-type" NF-kappaB-inhibitory phenotype, as indicated by decreased NF-kappaB migration to infected cell nuclei and interference in transcription. Thus, in 293T cells, VV apparently utilizes its M2L protein to interfere with a step(s) that would otherwise enable ERK2 phosphorylation and the consequential activation of an NF-kappaBeta response.

Gene expression profiling in vLINCL CLN6-deficient fibroblasts: Insights into pathobiology

The CLN6 vLINCL is caused by molecular defects in CLN6 gene coding for an ER resident transmembrane protein whose function is unknown. In the present study gene expression profiling of CLN6-deficient fibroblasts using cDNA microarray was undertaken in order to provide novel insights into the molecular mechanisms underlying this neurodegenerative fatal disease. Data were validated by qRT-PCR. Statistically significant alterations of expression were observed for 12 transcripts. The two most overexpressed genes, versican and tissue factor pathway inhibitor 2, are related to extracellular matrix (ECM), predicting changes in ECM-related proteins in CLN6-deficient cells. Transcript profiling also suggested alterations in signal transduction pathways, apoptosis and the immune/inflammatory response. Up-regulated genes related to steroidogenesis or signalling, and the relationship between cholesterol dynamics and glycosphingolipid sorting, led to investigation of free cholesterol and gangliosides in CLN6-deficient fibroblasts. Cholesterol accumulation in lysosomes suggests a homeostasis block as a result of CLN6p deficiency. The cholesterol imbalance may affect structure/function of caveolae and lipid rafts, disrupting signalling transduction pathways and sorting cell mechanisms. Alterations in protein/lipid intracellular trafficking would affect the composition and function of endocytic compartments, including lysosomes. Dysfunctional endosomal/lysosomal vesicles may act as one of the triggers for apoptosis and cell death, and for a secondary protective inflammatory response. In conclusion, the data reported provide novel clues into molecular pathophysiological mechanisms of CLN6-deficiency, and may also help in developing disease biomarkers and therapies for this and other neurodegenerative diseases.

Sequential 5-Aza 2'-deoxycytidine/depsipeptide FK228 treatment induces tissue factor pathway inhibitor 2 (TFPI-2) expression in cancer cells

cDNA arrays were used to examine gene induction in CALU-6 and H460 lung cancer cells mediated by sequential 5-aza 2'-deoxycytidine (DAC)/depsipeptide FK228 (DP) exposure in order to identify translational end points for clinical trials evaluating these agents. In both cell lines, sequential DAC/DP treatment induced expression of tissue factor pathway inhibitor-2 (TFPI-2), an inhibitor of Factor VII: tissue factor signal transduction known to diminish the malignant phenotype of cancer cells. TFPI-2 expression was diminished or absent in 16 of 32 cell lines established from thoracic malignancies. Sequential DAC/DP treatment induced TFPI-2 in cancer cells deficient for TFPI-2 expression in the basal state. Promoter methylation coincided with loss of TFPI-2 expression in a number of cancer lines. TFPI-2 promoter methylation was observed in one of five pulmonary adenocarcinomas, and seven of seven esophageal adenocarcinomas, but not corresponding normal tissues. DP enhanced acetylation of TFPI-2-associated histones in CALU-6 cells. DP or PDBU, alone, induced TFPI-2 expression in cancer cells deficient for TFPI-2 expression in the absence of promoter methylation. In these cells, DP-mediated TFPI-2 induction was abrogated by calphostin. Induction of TFPI-2 by distinct, yet cooperative mechanisms involving chromatin remodeling and PKC signaling strengthens the preclinical rationale for sequential administration of DNA demethylating agents and HDAC inhibitors in cancer patients. Furthermore, induction of TFPI-2 may be a useful surrogate marker of treatment response in individuals receiving sequential DAC/DP infusions.

Epigenetic inactivation of TFPI-2 as a common mechanism associated with growth and invasion of pancreatic ductal adenocarcinoma

Using microarrays, we have screened for genes reactivated by drugs that modify epigenetic mechanisms in pancreatic cancer cells. One of the genes identified was tissue factor pathway inhibitor 2 (TFPI-2), which encodes for a broad-spectrum serine proteinase inhibitor that negatively regulates the extracellular matrix degradation, an essential step in tumor invasion and metastasis. We therefore investigated the expression and methylation patterns of the TFPI-2 gene in pancreatic adenocarcinoma, and determined its role in tumor growth and invasion. In contrast to its abundant expression in normal pancreas, TFPI-2 mRNA was undetectable in a high fraction of pancreatic cancer cell lines and in primary pancreatic ductal neoplasms (IPMNs). Loss of TFPI-2 expression was associated with aberrant hypermethylation of its promoter CpG island. Treatment with the phorbol ester (PMA), known to stimulate the TFPI-2 promoter activity, augmented the TFPI-2 expression in cell lines with unmethylated or partially methylated TFPI-2, but failed to induce the expression in cell lines that harbored fully methylated TFPI-2. Aberrant methylation of TFPI-2 was also detected in 73% (102/140) of pancreatic cancer xenografts and primary pancreatic adenocarcinomas, was more likely in older patients with pancreatic cancer, and significantly correlated with progression of IPMNs (P=0.0002). Restored expression of the TFPI-2 gene in nonexpressing pancreatic cancer cells resulted in marked suppression in their proliferation, migration, and invasive potential in vitro. We thus conclude that epigenetic inactivation of TFPI-2 is a common mechanism that contributes to the aggressive phenotype of pancreatic ductal adenocarcinoma.

Expression and methylation status of tissue factor pathway inhibitor-2 gene in non-small-cell lung cancer

Tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type serine proteinase inhibitor that inhibits plasmin-dependent activation of several metalloproteinases. Downregulation of TFPI-2 could thus enhance the invasive potential of neoplastic cells in several cancers, including lung cancer. In this study, TFPI-2 mRNA was measured using a real-time PCR method in tumours of 59 patients with non-small-cell lung cancer (NSCLC). Tumour TFPI-2 mRNA levels appeared well correlated with protein expression evaluated by immunohistochemistry and were 4-120 times lower compared to those of nonaffected lung tissue in 22 cases (37%). Hypermethylation of the TFPI-2 gene promoter was demonstrated by restriction enzyme-polymerase chain reaction in 12 of 40 cases of NSCLC (30%), including nine of 17 for whom tumour TFPI-2 gene expression was lower than in noncancerous tissue. In contrast, this epigenetic modification was shown in only three of 23 tumours in which no decrease in TFPI-2 synthesis was found (P=0.016). Decreased TFPI-2 gene expression and hypermethylation were more frequently associated with stages III or IV NSCLC (eight out of 10, P=0.02) and the TFPI-2 gene promoter was more frequently hypermethylated in patients with lymph node metastases (eight out of 16, P=0.02). These results suggest that silencing of the TFPI-2 gene by hypermethylation might contribute to tumour progression in NSCLC.

Transient transfection of epidermal growth factor receptor gene into MCF7 breast ductal carcinoma cell line

Epidermal growth factor receptor (EGFR) is activated by autocrine growth factors in many types of tumours, including breast tumours. This receptor has been linked to a poor prognosis in breast cancer and may promote proliferation, migration, invasion, and cell survival as well as inhibition of apoptosis. Human breast ductal carcinoma MCF7 cells were transfected using FuGENE 6 with 1 microg of pcDNA3-EGFR containing the full-length human EGFR promoter or 1 microg of the vectors alone (pcDNA3). The transfected cells were transferred into a 25-cm2 flask containing growth medium and G418. Confluent cultures were lysed, total protein levels measured and electrophoresed. The electrophoresed samples were transferred to nitrocellulose and incubated overnight at 4 degrees C with either anti-EGFR or anti-phospho-ERK and immunoreactive bands were visualized using HRP-linked secondary antibody. We created a model system of EGFR overexpression in MCF7 clones with stably transfected pcDNA3/EGFR plasmid. These cells have been shown to promote substantial phosphorylation of both ERK1 and ERK2. The high level of EGFR and ERK1/2 phosphorylation was not seen in the pcDNA3 vector control cells or in non-transfected cells. In this article we describe successful transient transfection experiments on MCF7 cells using the FuGENE 6 Transfection Reagent. The overexpression of EGFR could be a mediated stress response and a survival signal that involves ERK1 and ERK2 phosphorylation.