Id1 and Id3 are required for neurogenesis, angiogenesis and vascularization of tumour xenografts

Terminal Differentiation of Adult Hippocampal Progenitor Cells Is a Step Functionally Dissociable from Proliferation and Is Controlled by Tis21, Id3 and NeuroD2

Cell proliferation and differentiation are interdependent processes. Here, we have asked to what extent the two processes of neural progenitor cell amplification and differentiation are functionally separated. Thus, we analyzed whether it is possible to rescue a defect of terminal differentiation in progenitor cells of the dentate gyrus, where new neurons are generated throughout life, by inducing their proliferation and/or their differentiation with different stimuli appropriately timed. As a model we used the Tis21 knockout mouse, whose dentate gyrus neurons, as demonstrated by us and others, have an intrinsic defect of terminal differentiation. We first tested the effect of two proliferative as well as differentiative neurogenic stimuli, one pharmacological (fluoxetine), the other cognitive (the Morris water maze (MWM) training). Both effectively enhanced the number of new dentate gyrus neurons produced, and fluoxetine also reduced the S-phase length of Tis21 knockout dentate gyrus progenitor cells and increased the rate of differentiation of control cells, but neither factor enhanced the defective rate of differentiation. In contrast, the defect of terminal differentiation was fully rescued by in vivo infection of proliferating dentate gyrus progenitor cells with retroviruses either silencing Id3, an inhibitor of neural differentiation, or expressing NeuroD2, a proneural gene expressed in terminally differentiated dentate gyrus neurons. This is the first demonstration that NeuroD2 or the silencing of Id3 can activate the differentiation of dentate gyrus neurons, complementing a defect of differentiation. It also highlights how the rate of differentiation of dentate gyrus neurons is regulated genetically at several levels and that a neurogenic stimulus for amplification of neural stem/progenitor cells may not be sufficient in itself to modify this rate.

The doublesex-related Dmrta2 safeguards neural progenitor maintenance involving transcriptional regulation of Hes1

The mechanisms that determine whether a neural progenitor cell (NPC) reenters the cell cycle or exits and differentiates are pivotal for generating cells in the correct numbers and diverse types, and thus dictate proper brain development. Combining gain-of-function and loss-of-function approaches in an embryonic stem cell-derived cortical differentiation model, we report that doublesex- and mab-3-related transcription factor a2 (Dmrta2, also known as Dmrt5) plays an important role in maintaining NPCs in the cell cycle. Temporally controlled expression of transgenic Dmrta2 in NPCs suppresses differentiation without affecting their neurogenic competence. In contrast, Dmrta2 knockout accelerates the cell cycle exit and differentiation into postmitotic neurons of NPCs derived from embryonic stem cells and in Emx1-cre conditional mutant mice. Dmrta2 function is linked to the regulation of Hes1 and other proneural genes, as demonstrated by genome-wide RNA-seq and direct binding of Dmrta2 to the Hes1 genomic locus. Moreover, transient Hes1 expression rescues precocious neurogenesis in Dmrta2 knockout NPCs. Our study thus establishes a link between Dmrta2 modulation of Hes1 expression and the maintenance of NPCs during cortical development.

Role of ID Proteins in BMP4 Inhibition of Profibrotic Effects of TGF-β2 in Human TM Cells

Purpose

Increased expression of TGF-β2 in primary open-angle glaucoma (POAG) aqueous humor (AH) and trabecular meshwork (TM) causes deposition of extracellular matrix (ECM) in the TM and elevated IOP. Bone morphogenetic proteins (BMPs) regulate TGF-β2–induced ECM production. The underlying mechanism for BMP4 inhibition of TGF-β2–induced fibrosis remains undetermined. Bone morphogenic protein 4 induces inhibitor of DNA binding proteins (ID1, ID3), which suppress transcription factor activities to regulate gene expression. Our study will determine whether ID1and ID3 proteins are downstream targets of BMP4, which attenuates TGF-β2 induction of ECM proteins in TM cells.

Methods

Primary human TM cells were treated with BMP4, and ID1 and ID3 mRNA, and protein expression was determined by quantitative PCR (Q-PCR) and Western immunoblotting. Intracellular ID1 and ID3 protein localization was studied by immunocytochemistry. Transformed human TM cells (GTM3 cells) were transfected with ID1 or ID3 expression vectors to determine their potential inhibitory effects on TGF-β2–induced fibronectin and plasminogen activator inhibitor-I (PAI-1) protein expression.

Results

Basal expression of ID1-3 was detected in primary human TM cells. Bone morphogenic protein 4 significantly induced early expression of ID1 and ID3 mRNA (P < 0.05) and protein in primary TM cells, and a BMP receptor inhibitor blocked this induction. Overexpression of ID1 and ID3 significantly inhibited TGF-β2–induced expression of fibronectin and PAI-1 in TM cells (P < 0.01).

Conclusions

Bone morphogenic protein 4 induced ID1 and ID3 expression suppresses TGF-β2 profibrotic activity in human TM cells. In the future, targeting specific regulators may control the TGF-β2 profibrotic effects on the TM, leading to disease modifying IOP lowering therapies.

Notch: an interactive player in neurogenesis and disease

Notch signaling is evolutionarily conserved from Drosophila to human. It plays critical roles in neural stem cell maintenance and neurogenesis in the embryonic brain as well as in the adult brain. Notch functions greatly depend on careful regulation and cross-talk with other regulatory mechanisms. Deregulation of Notch signaling is involved in many neurodegenerative diseases and brain disorders. Here, we summarize the fundamental role of Notch in neuronal development and specification and discuss how epigenetic regulation and pathway cross-talk contribute to Notch function. In addition, we cover aberrant alterations of Notch signaling in the diseased brain. The aim of this review is to provide an insight into how Notch signaling works in different contexts to control neurogenesis and its potential effects in diagnoses and therapies of neurodegeneration, brain tumors and disorders.

Minimal residual disease in melanoma: circulating melanoma cells and predictive role of MCAM/MUC18/MelCAM/CD146

Circulating tumour cells (CTCs), identified in numerous cancers including melanoma, are unquestionably considered valuable and useful as diagnostic and prognostic markers. They can be detected at all melanoma stages and may persist long after treatment. A crucial step in metastatic processes is the intravascular invasion of neoplastic cells as circulating melanoma cells (CMCs). Only a small percentage of these released cells are efficient and capable of colonizing with a strong metastatic potential. CMCs' ability to survive in circulation express a variety of genes with continuous changes of signal pathways and proteins to escape immune surveillance. This makes it difficult to detect them; therefore, specific isolation, enrichment and characterization of CMC population could be useful to monitor disease status and patient clinical outcome. Overall and disease-free survival have been correlated with the presence of CMCs. Specific melanoma antigens, in particular MCAM (MUC18/MelCAM/CD146), could be a potentially useful tool to isolate CMCs as well as be a prognostic, predictive biomarker. These are the areas reviewed in the article.

Prognostic stratification improvement by integrating ID1/ID3/IGJ gene expression signature and immunophenotypic profile in adult patients with B-ALL

Background

Survival of adults with B-Acute Lymphoblastic Leukemia requires accurate risk stratification of patients in order to provide the appropriate therapy. Contemporary techniques, using clinical and cytogenetic variables are incomplete for prognosis prediction.

Methods

To improve the classification of adult patients diagnosed with B-ALL into prognosis groups, two strategies were examined and combined: the expression of the ID1/ID3/IGJ gene signature by RT-PCR and the immunophenotypic profile of 19 markers proposed in the EuroFlow protocol by Flow Cytometry in bone marrow samples.

Results

Both techniques were correlated to stratify patients into prognostic groups. An inverse relationship between survival and expression of the three-genes signature was observed and an immunophenotypic profile associated with clinical outcome was identified. Markers CD10 and CD20 were correlated with simultaneous overexpression of ID1, ID3 and IGJ. Patients with simultaneous expression of the poor prognosis gene signature and overexpression of CD10 or CD20, had worse Event Free Survival and Overall Survival than patients who had either the poor prognosis gene expression signature or only CD20 or CD10 overexpressed.

Conclusion

By utilizing the combined evaluation of these two immunophenotypic markers along with the poor prognosis gene expression signature, the risk stratification can be significantly strengthened. Further studies including a large number of patients are needed to confirm these findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0506-4) contains supplementary material, which is available to authorized users.

Cancer cell-secreted IGF2 instigates fibroblasts and bone marrow-derived vascular progenitor cells to promote cancer progression

Local interactions between cancer cells and stroma can produce systemic effects on distant organs to govern cancer progression. Here we show that IGF2 secreted by inhibitor of differentiation (Id1)-overexpressing oesophageal cancer cells instigates VEGFR1-positive bone marrow cells in the tumour macroenvironment to form pre-metastatic niches at distant sites by increasing VEGF secretion from cancer-associated fibroblasts. Cancer cells are then attracted to the metastatic site via the CXCL5/CXCR2 axis. Bone marrow cells transplanted from nude mice bearing Id1-overexpressing oesophageal tumours enhance tumour growth and metastasis in recipient mice, whereas systemic administration of VEGFR1 antibody abrogates these effects. Mechanistically, IGF2 regulates VEGF in fibroblasts via miR-29c in a p53-dependent manner. Analysis of patient serum samples showed that concurrent elevation of IGF2 and VEGF levels may serve as a prognostic biomarker for oesophageal cancer. These findings suggest that the Id1/IGF2/VEGF/VEGFR1 cascade plays a critical role in tumour-driven pathophysiological processes underlying cancer progression.

Zebrafish atoh8 mutants do not recapitulate morpholino phenotypes

Atoh8 is a bHLH transcription factor expressed in pancreas, skeletal muscle, the nervous system, and cardiovascular tissues during embryological development. Although it has been implicated in the regulation of pancreatic and endothelial cell differentiation, the phenotypic consequences of Atoh8 loss are uncertain. Conclusions from knockout studies in the mouse differ widely depending on the targeting strategy used, while atoh8 knockdown by interfering morpholino oligonucleotides (morpholinos) in zebrafish has led to a range of developmental defects. This study characterised zebrafish embryos homozygous for atoh8^sa1465, a loss-of-function allele of atoh8, in order to provide genetic evidence for the developmental role of Atoh8 in this species. Embryos homozygous for atoh8^sa1465 present normal body morphology, swimbladder inflation, and heart looping, and survive to adulthood. These embryos do not develop pericardial oedema by 72 hpf and are not sensitised to the loss of Fog1 protein, suggesting that this previously described abnormality is not a specific phenotype. Vascular patterning and primitive haematopoiesis are unaffected in atoh8^{sa1465/sa1465} mutant embryos. Together, the data suggest that Atoh8 is dispensible for zebrafish development under standard laboratory conditions.

Low grade inflammation inhibits VEGF induced HUVECs migration in p53 dependent manner

In the course of studying crosstalk between inflammation and angiogenesis, high doses of pro-inflammatory factors have been reported to induce apoptosis in cells. Under normal circumstances also the pro-inflammatory cytokines are being released in low doses and are actively involved in cell signaling pathways. We studied the effects of low grade inflammation in growth factor induced angiogenesis using tumor necrosis factor alfa (TNFα) and vascular endothelial growth factor A (VEGF) respectively. We found that low dose of TNFα can inhibit VEGF induced angiogenesis in human umbilical vein endothelial cells (HUVECs). Low dose of TNFα induces mild upregulation and moreover nuclear localization of tumor suppressor protein 53 (P53) which causes decrease in inhibitor of DNA binding-1 (Id1) expression and shuttling to the cytoplasm. In absence of Id1, HUVECs fail to upregulate β₃-integrin and cell migration is decreased. Connecting low dose of TNFα induced p53 to β₃-integrin through Id1, we present additional link in cross talk between inflammation and angiogenesis.

The Id-protein family in developmental and cancer-associated pathways

Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.

The Id-protein family in developmental and cancer-associated pathways

Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.

ID(ealizing) control of adult subventricular zone neural stem/precursor cell differentiation for CNS regeneration

The adult central nervous system (CNS) was considered a comparatively static tissue with little cell turnover. It is now well established that there is more plasticity than previously thought and that astrocytes act as neural stem/precursor cells (NSPCs) in the subventricular zone (SVZ). The discovery that these NSPCs can give rise to a limited number of new neurons, reactive astrocytes and oligodendrocytes contributing to brain repair in CNS disease, has raised hopes toward harnessing these cells for therapeutic interventions. Here, we will discuss the transcriptional control of adult NSPC differentiation into astrocytes in CNS disease focusing on the helix-loop-helix transcription factor protein family. In our recent study, we reported that elevated BMP-2 levels are translated into an increase in Id3 expression in adult NSPC subpopulations after cortical injury. Id3 then heterodimerizes with the basic helix-loop-helix transcription factor E47 and releases the E47-mediated repression of astrocyte-specific gene expression. Consequently, adult NSPCs preferentially differentiate into astrocytes. We believe that understanding the in vivo differentiation potential and the molecular underpinnings of NSPCs in the adult mammalian brain will help us to evaluate their contributions to brain repair and may lead to new concepts in treating human CNS diseases.

Unraveling the differential dynamics of developmental fate in central and peripheral nervous systems

Bone morphogenetic protein 2 (BMP2), differentially regulates the developmental lineage commitment of neural stem cells (NSC’s) in central and peripheral nervous systems. However, the precise mechanism beneath such observations still remains illusive. To decipher the intricacies of this mechanism, we propose a generic mathematical model of BMP2 driven differentiation regulation of NSC’s. The model efficiently captures the dynamics of the wild-type as well as various mutant and over-expression phenotypes for NSC’s in central nervous system. Our model predicts that the differential developmental dynamics of the NSC’s in peripheral nervous system can be reconciled by altering the relative positions of the two mutually interconnected bi-unstable switches inherently present in the steady state dynamics of the crucial developmental fate regulatory proteins as a function of BMP2 dose. This model thus provides a novel mechanistic insight and has the potential to deliver exciting therapeutic strategies for neuronal regeneration from NSC’s of different origin.

BMP-SMAD-ID promotes reprogramming to pluripotency by inhibiting p16/INK4A-dependent senescence

Fibrodysplasia ossificans progressiva (FOP) patients carry a missense mutation in ACVR1 [617G > A (R206H)] that leads to hyperactivation of BMP-SMAD signaling. Contrary to a previous study, here we show that FOP fibroblasts showed an increased efficiency of induced pluripotent stem cell (iPSC) generation. This positive effect was attenuated by inhibitors of BMP-SMAD signaling (Dorsomorphin or LDN1931890) or transducing inhibitory SMADs (SMAD6 or SMAD7). In normal fibroblasts, the efficiency of iPSC generation was enhanced by transducing mutant ACVR1 (617G > A) or SMAD1 or adding BMP4 protein at early times during the reprogramming. In contrast, adding BMP4 at later times decreased iPSC generation. ID genes, transcriptional targets of BMP-SMAD signaling, were critical for iPSC generation. The BMP-SMAD-ID signaling axis suppressed p16/INK4A-mediated cell senescence, a major barrier to reprogramming. These results using patient cells carrying the ACVR1 R206H mutation reveal how cellular signaling and gene expression change during the reprogramming processes.

Inhibitor of DNA-binding 1 promotes endothelial progenitor cell proliferation and migration by suppressing E2-2 through the helix-loop-helix domain

Vascular endothelial damage is the major contributing factor to cardiovascular diseases. Recently, the therapeutic significance of endothelial progenitor cells (EPCs) has drawn increasing attention due to their roles in re-endothelialization following injury. The inhibitor of DNA-binding 1 (ID1) has been proven to promote EPC proliferation and migration, suggesting a critical function of ID1 in re-endothelialization. However, the underlying mechanisms remain undefined. In this study, ID1 was found to interact with E2-2 using immunoprecipitation analysis. Moreover, ID1 overexpression suppressed E2-2 expression and luciferase reporter activity; however, these effects were not observed in cells transfected with ID1 lacking the helix-loop-helix (HLH) domain (ID1ΔHLH). Further functional analysis corroborated that the upregulation of E2-2 markedly attenuated the ID1-mediated increase in EPC proliferation and migration. Furthermore, the HLH domain plays an important role in ID1-induced EPC proliferation and migration, as its deletion suppressed the positive regulatory effects of ID1 on EPC proliferation and migration. Taken together, the findings of our study confirm that ID1 promotes EPC proliferation and migration by suppressing E2-2 through the HLH domain in ID1. Therefore, ID1 may represent a potential therapeutic target for EPC-mediated re-endothelialization following vascular injury.

Specification of tissue-resident macrophages during organogenesis

Tissue-resident macrophages support embryonic development and tissue homeostasis and repair. The mechanisms that control their differentiation remain unclear. We report here that erythro-myeloid progenitors in mice generate premacrophages (pMacs) that simultaneously colonize the whole embryo from embryonic day 9.5 in a chemokine-receptor-dependent manner. The core macrophage program initiated in pMacs is rapidly diversified as expression of transcriptional regulators becomes tissue-specific in early macrophages. This process appears essential for macrophage specification and maintenance, as inactivation of Id3 impairs the development of liver macrophages and results in selective Kupffer cell deficiency in adults. We propose that macrophage differentiation is an integral part of organogenesis, as colonization of organ anlagen by pMacs is followed by their specification into tissue macrophages, hereby generating the macrophage diversity observed in postnatal tissues.

PAFAH1B1 and the lncRNA NONHSAT073641 maintain an angiogenic phenotype in human endothelial cells

AIM

Platelet-activating factor acetyl hydrolase 1B1 (PAFAH1B1, also known as Lis1) is a protein essentially involved in neurogenesis and mostly studied in the nervous system. As we observed a significant expression of PAFAH1B1 in the vascular system, we hypothesized that PAFAH1B1 is important during angiogenesis of endothelial cells as well as in human vascular diseases.

METHOD

The functional relevance of the protein in endothelial cell angiogenic function, its downstream targets and the influence of NONHSAT073641, a long non-coding RNA (lncRNA) with 92% similarity to PAFAH1B1, were studied by knockdown and overexpression in human umbilical vein endothelial cells (HUVEC).

RESULTS

Knockdown of PAFAH1B1 led to impaired tube formation of HUVEC and decreased sprouting in the spheroid assay. Accordingly, the overexpression of PAFAH1B1 increased tube number, sprout length and sprout number. LncRNA NONHSAT073641 behaved similarly. Microarray analysis after PAFAH1B1 knockdown and its overexpression indicated that the protein maintains Matrix Gla Protein (MGP) expression. Chromatin immunoprecipitation experiments revealed that PAFAH1B1 is required for active histone marks and proper binding of RNA Polymerase II to the transcriptional start site of MGP. MGP itself was required for endothelial angiogenic capacity and knockdown of both, PAFAH1B1 and MGP, reduced migration. In vascular samples of patients with chronic thromboembolic pulmonary hypertension (CTEPH), PAFAH1B1 and MGP were upregulated. The function of PAFAH1B1 required the presence of the intact protein as overexpression of NONHSAT073641, which was highly upregulated during CTEPH, did not affect PAFAH1B1 target genes.

CONCLUSION

PAFAH1B1 and NONHSAT073641 are important for endothelial angiogenic function.

The ID1-CULLIN3 Axis Regulates Intracellular SHH and WNT Signaling in Glioblastoma Stem Cells

Inhibitor of differentiation 1 (ID1) is highly expressed in glioblastoma stem cells (GSCs). However, the regulatory mechanism responsible for its role in GSCs is poorly understood. Here, we report that ID1 activates GSC proliferation, self-renewal, and tumorigenicity by suppressing CULLIN3 ubiquitin ligase. ID1 induces cell proliferation through increase of CYCLIN E, a target molecule of CULLIN3. ID1 overexpression or CULLIN3 knockdown confers GSC features and tumorigenicity to murine Ink4a/Arf-deficient astrocytes. Proteomics analysis revealed that CULLIN3 interacts with GLI2 and DVL2 and induces their degradation via ubiquitination. Consistent with ID1 knockdown or CULLIN3 overexpression in human GSCs, pharmacologically combined control of GLI2 and β-CATENIN effectively diminishes GSC properties. A ID1-high/CULLIN3-low expression signature correlates with a poor patient prognosis, supporting the clinical relevance of this signaling axis. Taken together, a loss of CULLIN3 represents a common signaling node for controlling the activity of intracellular WNT and SHH signaling pathways mediated by ID1.

Id2 Mediates Differentiation of Labyrinthine Placental Progenitor Cell Line, SM10

The placenta is an organ that is formed transiently during pregnancy, and appropriate placental development is necessary for fetal survival and growth. Proper differentiation of the labyrinthine layer of the placenta is especially crucial, as it establishes the fetal-maternal interface that is involved in physiological exchange processes. Although previous studies have indicated the importance of inhibitor of differentiation/inhibitor of DNA binding-2 (Id2) helix-loop-helix transcriptional regulator in mediating cell differentiation, the ability of Id2 to regulate differentiation toward the labyrinthine (transport) lineage of the placenta has yet to be determined. In the current study, we have generated labyrinthine trophoblast progenitor cells with increased (SM10-Id2) or decreased (SM10-Id2-shRNA) Id2 expression and determined the effect on TGF-β-induced differentiation. Our Id2 overexpression and knockdown analyses indicate that Id2 mediates TGF-β-induced morphological differentiation of labyrinthine trophoblast cells, as Id2 overexpression prevents differentiation and Id2 knockdown results in differentiation. Thus, our data indicate that Id2 is an important molecular mediator of labyrinthine trophoblast differentiation. An understanding of the regulators of trophoblast progenitor differentiation toward the labyrinthine lineage may offer insights into events governing pregnancy-associated disorders, such as placental insufficiency, fetal growth restriction, and preeclampsia.

Combined Id1 and Id3 Deletion Leads to Severe Erythropoietic Disturbances

The Inhibitor of DNA Binding (Id) proteins play a crucial role in regulating hematopoiesis and are known to interact with E proteins and the bHLH family of transcription factors. Current efforts seek to elucidate the individual roles of Id members in regulating hematopoietic development and specification. However, the nature of their functional redundancies remains elusive since ablation of multiple Id genes is embryonically lethal. We developed a model to test this compensation in the adult. We report that global Id3 ablation with Tie2Cre-mediated conditional ablation of Id1 in both hematopoietic and endothelial cells (Id cDKO) extends viability to 1 year but leads to multi-lineage hematopoietic defects including the emergence of anemia associated with defective erythroid development, a novel phenotype unreported in prior single Id knockout studies. We observe decreased cell counts in the bone marrow and splenomegaly to dimensions beyond what is seen in single Id knockout models. Transcriptional dysregulation of hematopoietic regulators observed in bone marrow cells is also magnified in the spleen. E47 protein levels were elevated in Id cDKO bone marrow cell isolates, but decreased in the erythroid lineage. Chromatin immunoprecipitation (ChIP) studies reveal increased occupancy of E47 and GATA1 at the promoter regions of β-globin and E2A. Bone marrow transplantation studies highlight the importance of intrinsic Id signals in maintaining hematopoietic homeostasis while revealing a strong extrinsic influence in the development of anemia. Together, these findings demonstrate that loss of Id compensation leads to dysregulation of the hematopoietic transcriptional network and multiple defects in erythropoietic development in adult mice.

Deguelin inhibits vasculogenic function of endothelial progenitor cells in tumor progression and metastasis via suppression of focal adhesion

Deguelin is a nature-derived chemopreventive drug. Endothelial progenitor cells (EPCs) are bone-marrow (BM)-derived key components to induce new blood vessels in early tumorigenesis and metastasis. Here we determined whether deguelin inhibits EPC function in vitro and in vivo at doses not affecting cancer cell apoptosis. Deguelin significantly reduced the number of EPC colony forming units of BM-derived c-kit+/sca-1+ mononuclear cells (MNCs), proliferation, migration, and adhesion to endothelial cell monolayers, and suppressed incorporation of EPC into tube-like vessel networks when co-cultured with endothelial cells. Deguelin caused cell cycle arrest at G1 without induction of apoptosis in EPC. In a mouse tumor xenograft model, tumor growth, lung metastasis and tumor-induced circulating EPCs were supressed by deguelin treatment (2 mg/kg). In mice tranplanted with GFP-expressing BM-MNCs, deguelin reduced the co-localization of CD31 and GFP, suggesting suppression of BM-derived EPC incoporation into tumor vessels. Interestingly, focal adhesion kinase (FAK)-integrin-linked kinase (ILK) activation and actin polymerization were repressed by deguelin. Decreased number of focal adhesions and a depolarized morphology was found in deguelin-treated EPCs. Taken together, our results suggest that the deguelin inhibits tumorigenesis and metastasis via EPC suppression and that suppression of focal adhesion by FAK-integrin-ILK-dependent actin remodeling is a key underlying molecular mechanism.

Inhibitory effect of MyoD on the proliferation of breast cancer cells

Skeletal muscle is rich in lymphatic vessels, with an abundant blood supply, and it is an infrequent site of cancer metastasis. Previous studies have demonstrated that enhanced secretion of MyoD may occur when skeletal muscle is injured or becomes cancerous. It was hypothesized that MyoD may act as an endogenous cytokine to inhibit the proliferation of cancer cells. To verify the possible effect of this protein on tumor cell proliferation, C2C12 mouse skeletal muscle cells and 4T1 mouse breast cancer cells were co-cultured using embedded Transwell plates. Following co-culture, cell cycle analysis revealed that C2C12 muscle cells were able to inhibit the proliferation of the breast cancer cells. Subsequently, MyoD was silenced in C2C12 cells to assess its effect on 4T1 cell proliferation. Following co-culture with MyoD-silenced cells, a 5-ethynyl-20-deoxyuridine assay indicated that MyoD silencing prevented the reduction in proliferation of 4T1 cells induced by untransfected C2C12 cells. In summary, the results indicated that MyoD inhibits the proliferation of breast cancer cells and may be a tumor suppressor factor.

Inflammatory properties of inhibitor of DNA binding 1 secreted by synovial fibroblasts in rheumatoid arthritis

Background

Inhibitor of DNA binding 1 (Id1) is a nuclear protein containing a basic helix-loop-helix (bHLH) domain that regulates cell growth by selective binding and prevention of gene transcription. Sources of Id1 production in rheumatoid arthritis synovial tissue (RA ST) and its range of functional effects in RA remain to be clarified.

Methods

We analyzed Id1 produced from synovial fibroblasts and endothelial cells (ECs) with histology and real-time polymerase chain reaction (RT-PCR). Fibroblast supernatants subjected to differential centrifugation to isolate and purify exosomes were measured for Id1 by enzyme-linked immunosorbent assay (ELISA). Western blotting of Id1-stimulated ECs was performed to determine the kinetics of intracellular protein phosphorylation. EC intracellular signaling pathways induced by Id1 were subsequently targeted with silencing RNA (siRNA) for angiogenesis inhibition.

Results

By PCR and histologic analysis, we found that the primary source of Id1 in STs is from activated fibroblasts that correlate with inflammatory scores in human RA ST and in joints from K/BxN serum-induced mice. Normal (NL) and RA synovial fibroblasts increase Id1 production with stimulation by transforming growth factor beta (TGF-β). Most of the Id1 released by RA synovial fibroblasts is contained within exosomes. Endothelial progenitor cells (EPCs) and human dermal microvascular ECs (HMVECs) activate the Jnk signaling pathway in response to Id1, and Jnk siRNA reverses Id1-induced HMVEC vessel formation in Matrigel plugs in vivo.

Conclusions

Id1 is a pleotropic molecule affecting angiogenesis, vasculogenesis, and fibrosis. Our data shows that Id1 is not only an important nuclear protein, but also can be released from fibroblasts via exosomes. The ability of extracellular Id1 to activate signaling pathways expands the role of Id1 in the orchestration of tissue inflammation.

Inhibition of BMP and of TGFβ receptors downregulates expression of XIAP and TAK1 leading to lung cancer cell death

Background

Bone morphogenetic proteins (BMP) are embryonic proteins that are part of the transforming growth factor (TGFβ) superfamily, which are aberrantly expressed in many carcinomas. Inhibition of BMP receptors with small molecule inhibitors decreases growth and induces death of lung cancer cells, which involves the downregulation of Id1 and Id3 by a Smad dependent mechanism. Developmentally, BMP and TGFβ signaling utilizes Smad-1/5 independent mechanisms to stabilize the expression of X-linked inhibitor of apoptosis protein (XIAP) and activate TGFβ activated kinase 1 (TAK1), which are known to be potent inhibitors of apoptosis. The role of BMP signaling in regulating XIAP and TAK1 in cancer cells is poorly understood. Furthermore, the interaction between the BMP and TGFβ signaling cascades in regulating the activation of TAK1 in cancer cells has not been elucidated.

Methods

Feedback regulation between the BMP and TGFβ signaling pathways and their regulation of XIAP, TAK1, and Id1 were examined in lung cancer cells utilizing siRNA and inhibitors targeting BMP type I receptors, inhibitors of BMP and TGFβ type I receptors, and an inhibitor of BMP and TGFβ type I and type II receptors.

Results

We show that upon inhibition of BMP signaling in lung cancer cells, the TGFβ signaling cascade is activated. Both the BMP and TGFβ pathways activate TAK1, which then increases the expression of Id1. Inhibition of TGFβ signaling increased Id1 expression except when BMP signaling is suppressed, which then causes a dose-related decrease in the expression of Id1. Inhibition of both BMP and TGFβ signaling enhances the downregulation of TAK1. Our data also suggests that the blockade of the BMP type II receptor enhances the downregulation XIAP, which is important in decreasing the activity of TAK1. Knockdown studies demonstrate that both XIAP and TAK1 regulate the survival of lung cancer cells.

Conclusions

This paper highlights that targeting the BMP and TGFβ type I and type II receptors causes a downregulation of XIAP, TAK1, and Id1 leading to cell death of lung cancer cells. Small molecule inhibitors targeting the BMP and TGFβ receptors represents a potential novel means to treat cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0511-9) contains supplementary material, which is available to authorized users.

High expression of ID family and IGJ genes signature as predictor of low induction treatment response and worst survival in adult Hispanic patients with B-acute lymphoblastic leukemia

Background

B-Acute lymphoblastic leukemia (B-ALL) represents a hematologic malignancy with poor clinical outcome and low survival rates in adult patients. Remission rates in Hispanic population are almost 30 % lower and Overall Survival (OS) nearly two years inferior than those reported in other ethnic groups. Only 61 % of Colombian adult patients with ALL achieve complete remission (CR), median overall survival is 11.3 months and event-free survival (EFS) is 7.34 months. Identification of prognostic factors is crucial for the application of proper treatment strategies and subsequently for successful outcome. Our goal was to identify a gene expression signature that might correlate with response to therapy and evaluate the utility of these as prognostic tool in hispanic patients.

Methods

We included 43 adult patients newly diagnosed with B-ALL. We used microarray analysis in order to identify genes that distinguish poor from good response to treatment using differential gene expression analysis. The expression profile was validated by real-time PCR (RT-PCT).

Results

We identified 442 differentially expressed genes between responders and non-responders to induction treatment. Hierarchical analysis according to the expression of a 7-gene signature revealed 2 subsets of patients that differed in their clinical characteristics and outcome.

Conclusions

Our study suggests that response to induction treatment and clinical outcome of Hispanic patients can be predicted from the onset of the disease and that gene expression profiles can be used to stratify patient risk adequately and accurately. The present study represents the first that shows the gene expression profiling of B-ALL Colombian adults and its relevance for stratification in the early course of disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0333-z) contains supplementary material, which is available to authorized users.

Mutant p53 proteins alter cancer cell secretome and tumour microenvironment: Involvement in cancer invasion and metastasis

An ever-increasing number of studies highlight the role of mutant p53 proteins in the alteration of cancer cell secretome and in the modification of tumour microenvironment, sustaining an invasive phenotype of cancer cell. The knowledge of the molecular mechanisms underlying the interplay between mutant p53 proteins and the microenvironment is becoming fundamental for the identification of both efficient anticancer therapeutic strategies and novel serum biomarkers. In this review, we summarize the novel findings concerning the regulation of secreted molecules by cancer cells bearing mutant TP53 gene. In particular, we highlight data from available literature, suggesting that mutant p53 proteins are able to (i) alter the secretion of enzymes involved in the modulation of extracellular matrix components; (ii) alter the secretion of inflammatory cytokines; (iii) increase the extracellular acidification; and (iv) regulate the crosstalk between cancer and stromal cells.

Sustained delivery of siRNA/PEI complex from in situ forming hydrogels potently inhibits the proliferation of gastric cancer

Background

Gastric cancer remains a major cause of mortality and morbidity worldwide. In recent years, gene-based therapeutic strategies were confirmed promising in cancer inhibition and attracted great attention. RNA interference (RNAi) is a powerful tool for gene therapy and has been widely employed to aid in treatment for various diseases, especially cancers. However, effective delivery of small interfering RNA (siRNA) to target cells in vivo remains a challenge for that it is prone to degradation and only lasts a few days in rapidly dividing cells.

Methods

Due to its biocompatibility and well-established safety profile, collagen represents a favourable matrix for in-site drug delivery. In the study, collagen hydrogel was used as carriers to test the feasibility of localized and sustained delivery of Id1-targeted siRNA for in vivo gastric cancer inhibition. To enhance the siRNA delivery, cationic polyethylenimine (PEI) was further emplored for scallold modification. The efficacy of siRNA delivery and cancer inhibition were evaluated with multimodality of mehods in vitro and in vivo.

Results

Our results showed that addition of polyethylenimine (PEI) to collagen can facilitate entry of Id1-siRNA into target cells, prolong the silencing effect, and further inhibit tumor growth both in vitro and in vivo.

Conclusion

This collagen-based delivery system may facilitate the pathogenesis elucidation and design of effective therapies against gastric cancer.

Cox-2-derived PGE2 induces Id1-dependent radiation resistance and self-renewal in experimental glioblastoma

BACKGROUND

In glioblastoma (GBM), Id1 serves as a functional marker for self-renewing cancer stem-like cells. We investigated the mechanism by which cyclooxygenase-2 (Cox-2)-derived prostaglandin E2 (PGE2) induces Id1 and increases GBM self-renewal and radiation resistance.

METHODS

Mouse and human GBM cells were stimulated with dimethyl-PGE2 (dmPGE2), a stabilized form of PGE2, to test for Id1 induction. To elucidate the signal transduction pathway governing the increase in Id1, a combination of short interfering RNA knockdown and small molecule inhibitors and activators of PGE2 signaling were used. Western blotting, quantitative real-time (qRT)-PCR, and chromatin immunoprecipitation assays were employed. Sphere formation and radiation resistance were measured in cultured primary cells. Immunohistochemical analyses were carried out to evaluate the Cox-2-Id1 axis in experimental GBM.

RESULTS

In GBM cells, dmPGE2 stimulates the EP4 receptor leading to activation of ERK1/2 MAPK. This leads, in turn, to upregulation of the early growth response1 (Egr1) transcription factor and enhanced Id1 expression. Activation of this pathway increases self-renewal capacity and resistance to radiation-induced DNA damage, which are dependent on Id1.

CONCLUSIONS

In GBM, Cox-2-derived PGE2 induces Id1 via EP4-dependent activation of MAPK signaling and the Egr1 transcription factor. PGE2-mediated induction of Id1 is required for optimal tumor cell self-renewal and radiation resistance. Collectively, these findings identify Id1 as a key mediator of PGE2-dependent modulation of radiation response and lend insight into the mechanisms underlying radiation resistance in GBM patients.

Heparanase 2 Attenuates Head and Neck Tumor Vascularity and Growth

The endoglycosidase heparanase specifically cleaves the heparan sulfate (HS) side chains on proteoglycans, an activity that has been implicated strongly in tumor metastasis and angiogenesis. Heparanase-2 (Hpa2) is a close homolog of heparanase that lacks intrinsic HS-degrading activity but retains the capacity to bind HS with high affinity. In head and neck cancer patients, Hpa2 expression was markedly elevated, correlating with prolonged time to disease recurrence and inversely correlating with tumor cell dissemination to regional lymph nodes, suggesting that Hpa2 functions as a tumor suppressor. The molecular mechanism associated with favorable prognosis following Hpa2 induction is unclear. Here we provide evidence that Hpa2 overexpression in head and neck cancer cells markedly reduces tumor growth. Restrained tumor growth was associated with a prominent decrease in tumor vascularity (blood and lymph vessels), likely due to reduced Id1 expression, a transcription factor highly implicated in VEGF-A and VEGF-C gene regulation. We also noted that tumors produced by Hpa2-overexpressing cells are abundantly decorated with stromal cells and collagen deposition, correlating with a marked increase in lysyl oxidase expression. Notably, heparanase enzymatic activity was unimpaired in cells overexpressing Hpa2, suggesting that reduced tumor growth is not caused by heparanase regulation. Moreover, growth of tumor xenografts by Hpa2-overexpressing cells was unaffected by administration of a mAb that targets the heparin-binding domain of Hpa2, implying that Hpa2 function does not rely on heparanase or heparan sulfate. Cancer Res; 76(9); 2791-801. ©2016 AACR.

Heterogeneity of white adipose tissue: molecular basis and clinical implications

Adipose tissue is a highly heterogeneous endocrine organ. The heterogeneity among different anatomical depots stems from their intrinsic differences in cellular and physiological properties, including developmental origin, adipogenic and proliferative capacity, glucose and lipid metabolism, insulin sensitivity, hormonal control, thermogenic ability and vascularization. Additional factors that influence adipose tissue heterogeneity are genetic predisposition, environment, gender and age. Under obese condition, these depot-specific differences translate into specific fat distribution patterns, which are closely associated with differential cardiometabolic risks. For instance, individuals with central obesity are more susceptible to developing diabetes and cardiovascular complications, whereas those with peripheral obesity are more metabolically healthy. This review summarizes the clinical and mechanistic evidence for the depot-specific differences that give rise to different metabolic consequences, and provides therapeutic insights for targeted treatment of obesity.

E Proteins and ID Proteins: Helix-Loop-Helix Partners in Development and Disease

The basic Helix-Loop-Helix (bHLH) proteins represent a well-known class of transcriptional regulators. Many bHLH proteins act as heterodimers with members of a class of ubiquitous partners, the E proteins. A widely expressed class of inhibitory heterodimer partners-the Inhibitor of DNA-binding (ID) proteins-also exists. Genetic and molecular analyses in humans and in knockout mice implicate E proteins and ID proteins in a wide variety of diseases, belying the notion that they are non-specific partner proteins. Here, we explore relationships of E proteins and ID proteins to a variety of disease processes and highlight gaps in knowledge of disease mechanisms.

Id-1, Id-2, and Id-3 co-expression correlates with prognosis in stage I and II lung adenocarcinoma patients treated with surgery and adjuvant chemotherapy

Inhibitors of DNA binding/inhibitors of differentiation (Id) protein family have been shown to be involved in carcinogenesis. However, the roles of Id during lung adenocarcinoma (ADC) progression remain unclear. Eighty-eight ADC samples were evaluated for Id-1,2,3 level and angiogenesis (CD 34 and VEGF microvessel density) by immunohistochemistry and morphometry. The impact of these markers was tested on follow-up until death or recurrence. A significant difference between tumor and normal tissue was found for Id-1,2,3 expression (P < 0.01). In addition, high levels of nuclear Id-1 were associated with higher angiogenesis in the tumor stroma (P < 0.01). Equally significant was the association between patients in T1-stage and low cytoplasmic Id-2, as well as patients in stage-IIb and low Id-3. High cytoplasm Id-3 expression was also directly associated to lymph nodes metastasis (P = 0.05). Patients at stages I to III, with low Id-1 and Id-3 cytoplasm histoscores showed significant long metastasis-free survival time than those with high Id-1 or Id-3 expression (P = 0.04). Furthermore, high MVD-CD34 and MVD-VEGF expression were associated with short recurrence-free survival compared to low MVD-CD34 and MVD-VEGF expressions (P = 0.04). Cox model analyses controlled for age, lymph node metastasis, and adjuvant treatments showed that nuclear Id-1, cytoplasmic Id-3, and MVD-CD34 were significantly associated with survival time. Median score for nuclear Id-1 and cytoplasmic Id-3 divided patients in two groups, being that those with increased Id-1 and Id-3 presented higher risk of death. Ids showed an independent prognostic value in patients with lung ADC, regardless of disease stage. Id-1 and Id-3 should be considered new target candidates in the development of personalized therapy in lung ADC.

Phosphorylation Regulates Id2 Degradation and Mediates the Proliferation of Neural Precursor Cells

Inhibitor of DNA binding proteins (Id1-Id4) function to inhibit differentiation and promote proliferation of many different cell types. Among the Id family members, Id2 has been most extensively studied in the central nervous system (CNS). Id2 contributes to cultured neural precursor cell (NPC) proliferation as well as to the proliferation of CNS tumors such as glioblastoma that are likely to arise from NPC-like cells. We identified three phosphorylation sites near the N-terminus of Id2 in NPCs. To interrogate the importance of Id2 phosphorylation, Id2(-/-) NPCs were modified to express wild type (WT) Id2 or an Id2 mutant protein that could not be phosphorylated at the identified sites. We observed that NPCs expressing this mutant lacking phosphorylation near the N-terminus had higher steady-state levels of Id2 when compared to NPCs expressing WT Id2. This elevated level was the result of a longer half-life and reduced proteasome-mediated degradation. Moreover, NPCs expressing constitutively de-phosphorylated Id2 proliferated more rapidly than NPCs expressing WT Id2, a finding consistent with the well-characterized function of Id2 in driving proliferation. Observing that phosphorylation of Id2 modulates the degradation of this important cell-cycle regulator, we sought to identify a phosphatase that would stabilize Id2 enhancing its activity in NPCs and extended our analysis to include human glioblastoma-derived stem cells (GSCs). We found that expression of the phosphatase PP2A altered Id2 levels. Our findings suggest that inhibition of PP2A may be a novel strategy to regulate the proliferation of normal NPCs and malignant GSCs by decreasing Id2 levels. Stem Cells 2016;34:1321-1331.

Scleroderma dermal microvascular endothelial cells exhibit defective response to pro-angiogenic chemokines

OBJECTIVES

Angiogenesis plays a critical role in SSc (scleroderma). The aim of this study was to examine the expression of growth-regulated protein-γ (Gro-γ/CXCL3), granulocyte chemotactic protein 2 (GCP-2/CXCL6) and their receptor CXCR2 in endothelial cells (ECs) isolated from SSc skin and determine whether these cells mount an angiogenic response towards pro-angiogenic chemokines. The downstream signalling pathways as well as the pro-angiogenic transcription factor inhibitor of DNA-binding protein 1 (Id-1) were also examined.

METHODS

Skin biopsies were obtained from patients with dcSSc. ECs were isolated via magnetic positive selection. Angiogenesis was measured by EC chemotaxis assay.

RESULTS

Gro-γ/CXCL3 and GCP-2/CXCL6 were minimally expressed in both skin types but elevated in SSc serum. Pro-angiogenic chemokine mRNA was greater in SSc ECs than in normal ECs. SSc ECs did not migrate to vascular endothelial growth factor (VEGF), Gro-γ/CXCL3, GCP-2/CXCL6 or CXCL16. The signalling pathways stimulated by these chemokines were also dysregulated. Id-1 mRNA in SSc ECs was lower compared with normal ECs, and overexpression of Id-1 in SSc ECs increased their ability to migrate towards VEGF and CXCL16.

CONCLUSION

Our results show that SSc ECs are unable to respond to pro-angiogenic chemokines despite their increased expression in serum and ECs. This might be due to the differences in the signalling pathways activated by these chemokines in normal vs SSc ECs. In addition, the lower expression of Id-1 also decreases the angiogenic response. The inability of pro-angiogenic chemokines to promote EC migration provides an additional mechanism for the impaired angiogenesis that characterizes SSc.

Nicotine Reduces Survival via Augmentation of Paracrine HGF-MET Signaling in the Pancreatic Cancer Microenvironment

PURPOSE

The relationship between smoking and pancreatic cancer biology, particularly in the context of the heterogeneous microenvironment, remains incompletely defined. We hypothesized that nicotine exposure would lead to the augmentation of paracrine growth factor signaling between tumor-associated stroma (TAS) and pancreatic cancer cells, ultimately resulting in accelerated tumor growth and metastasis.

EXPERIMENTAL DESIGN

The effect of tobacco use on overall survival was analyzed using a prospectively maintained database of surgically resected patients with pancreatic cancer. Nicotine exposure was evaluated in vitro using primary patient-derived TAS and pancreatic cancer cells independently and in coculture. Nicotine administration was then assessed in vivo using a patient-derived pancreatic cancer xenograft model.

RESULTS

Continued smoking was associated with reduced overall survival after surgical resection. In culture, nicotine-stimulated hepatocyte growth factor (HGF) secretion in primary patient-derived TAS and nicotine stimulation was required for persistent pancreatic cancer cell c-Met activation in a coculture model. c-Met activation in this manner led to the induction of inhibitor of differentiation-1 (Id1) in pancreatic cancer cells, previously established as a mediator of growth, invasion and chemoresistance. HGF-induced Id1 expression was abrogated by both epigenetic and pharmacologic c-Met inhibition. In patient-derived pancreatic cancer xenografts, nicotine treatment augmented tumor growth and metastasis; tumor lysates from nicotine-treated mice demonstrated elevated HGF expression by qRT-PCR and phospho-Met levels by ELISA. Similarly, elevated levels of phospho-Met in surgically resected pancreatic cancer specimens correlated with reduced overall survival.

CONCLUSIONS

Taken together, these data demonstrate a novel, microenvironment-dependent paracrine signaling mechanism by which nicotine exposure promotes the growth and metastasis of pancreatic cancer.

Arteriovenous malformations in hereditary haemorrhagic telangiectasia: looking beyond ALK1-NOTCH interactions

Hereditary haemorrhagic telangiectasia (HHT) is characterized by the development of arteriovenous malformations--enlarged shunts allowing arterial flow to bypass capillaries and enter directly into veins. HHT is caused by mutations in ALK1 or Endoglin; however, the majority of arteriovenous malformations are idiopathic and arise spontaneously. Idiopathic arteriovenous malformations differ from those due to loss of ALK1 in terms of both location and disease progression. Furthermore, while arteriovenous malformations in HHT and Alk1 knockout models have decreased NOTCH signalling, some idiopathic arteriovenous malformations have increased NOTCH signalling. The pathogenesis of these lesions also differs, with loss of ALK1 causing expansion of the shunt through proliferation, and NOTCH gain of function inducing initial shunt enlargement by cellular hypertrophy. Hence, we propose that idiopathic arteriovenous malformations are distinct from those of HHT. In this review, we explore the role of ALK1-NOTCH interactions in the development of arteriovenous malformations and examine a possible role of two signalling pathways downstream of ALK1, TMEM100 and IDs, in the development of arteriovenous malformations in HHT. A nuanced understanding of the precise molecular mechanisms underlying idiopathic and HHT-associated arteriovenous malformations will allow for development of targeted treatments for these lesions.

Interacting mechanism of ID3 HLH domain towards E2A/E12 transcription factor - An Insight through molecular dynamics and docking approach

Inhibitor of DNA binding protein 3 (ID3) has long been characterized as an oncogene that implicates its functional role through its Helix-Loop-Helix (HLH) domain upon protein-protein interaction. An insight into the dimerization brought by this domain helps in identifying the key residues that favor the mechanism behind it. Molecular dynamics (MD) simulations were performed for the HLH proteins ID3 and Transcription factor E2-alpha (E2A/E12) and their ensemble complex (ID3-E2A/E12) to gather information about the HLH domain region and its role in the interaction process. Further evaluation of the results by Principal Component Analysis (PCA) and Free Energy Landscape (FEL) helped in revealing residues of E2A/E12: Lys570, Ala595, Val598, and Ile599 and ID3: Glu53, Gln63, and Gln66 buried in their HLH motifs imparting key roles in dimerization process. Furthermore the T-pad analysis results helped in identifying the key fluctuations and conformational transitions using the intrinsic properties of the residues present in the domain region of the proteins thus specifying their crucial role towards molecular recognition. The study provides an insight into the interacting mechanism of the ID3-E2A/E12 complex and maps the structural transitions arising in the essential conformational space indicating the key structural changes within the helical regions of the motif. It thereby describes how the internal dynamics of the proteins might regulate their intrinsic structural features and its subsequent functionality.

Peritoneal VEGF-A expression is regulated by TGF-β1 through an ID1 pathway in women with endometriosis

VEGF-A, an angiogenic factor, is increased in the peritoneal fluid of women with endometriosis. The cytokine TGF-β1 is thought to play a role in the establishment of endometriosis lesions. Inhibitor of DNA binding (ID) proteins are transcriptional targets of TGF-β1 and ID1 has been implicated in VEGF-A regulation during tumor angiogenesis. Herein, we determined whether peritoneal expression of VEGF-A is regulated by TGF-β1 through the ID1 pathway in women with endometriosis. VEGF-A was measured in peritoneal fluid by ELISA (n = 16). VEGF-A and ID1 expression was examined in peritoneal biopsies (n = 13), and primary peritoneal and immortalized mesothelial cells (MeT5A) by immunohistochemistry, qRT-PCR and ELISA. VEGF-A was increased in peritoneal fluid from women with endometriosis and levels correlated with TGF-β1 concentrations (P < 0.05). VEGF-A was immunolocalized to peritoneal mesothelium and TGF-β1 increased VEGFA mRNA (P < 0.05) and protein (P < 0.05) in mesothelial cells. ID1 was increased in peritoneum from women with endometriosis and TGF-β1 increased concentrations of ID1 mRNA (P < 0.05) in mesothelial cells. VEGF-A regulation through ID1 was confirmed by siRNA in MeT5A cells (P < 0.05). Our data supports role for ID1 in the pathophysiology of endometriosis, as an effector of TGFβ1 dependent upregulation of VEGF-A, and highlights a novel potential therapeutic target.

Id Proteins Contribute to Tumor Development and Metastatic Colonization in a Model of Bladder Carcinogenesis

Background: Bladder cancer is one of the most common malignant genitourinary diseases worldwide. Despite advances in surgical technique, medical oncology and radiation therapy, cure of invasive tumors remains elusive for patients with late stage disease. Therefore, new therapeutic strategies are needed to improve the response rates with regard to recurrence, invasion and metastasis.

Objective: Inhibitor of DNA binding (Id) proteins have been proposed as therapeutic targets due to the key regulatory role they exert in multiple steps of cancer. We aimed to explore the role of Id proteins in bladder cancer development and the pattern of expression of Id proteins in bladder carcinomas.

Methods: We used a well-established chemically induced model of bladder carcinogenesis. Wild type and Id-deficient mice were given N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in the drinking water and urinary bladder lesions were analyzed histopathologically and stained for Id1. We assessed the effects of Id1 inactivation in cultured bladder cancer cells and in a model of metastatic lung colonization. We also performed Id1 staining of human urothelial carcinoma samples and matched lymph node metastases.

Results: Id1 protein was overexpressed in the BBN-induced model of bladder cancer. Id1 deficiency resulted in the development of urinary bladder tumors with areas of extensive hemorrhage and decreased invasiveness when compared to wild type mice. Id1 inactivation led to decreased cell growth in vitro and lung colonization in vivo of human bladder cancer cells. Immunohistochemistry performed on human urothelial carcinoma samples showed Id1 positive staining in both primary tumors and lymph node metastases.

Conclusions: In summary, our studies reveal the physiological relevance of Id1 in bladder cancer progression and suggest that targeting Id1 may be important in the development of novel therapies for the treatment of bladder cancer.

The balance of Id3 and E47 determines neural stem/precursor cell differentiation into astrocytes

Adult neural stem/precursor cells (NSPCs) of the subventricular zone (SVZ) are an endogenous source for neuronal replacement in CNS disease. However, adult neurogenesis is compromised after brain injury in favor of a glial cell fate, which is mainly attributed to changes in the NSPC environment. Yet, it is unknown how this unfavorable extracellular environment translates into a transcriptional program altering NSPC differentiation. Here, we show that genetic depletion of the transcriptional regulator Id3 decreased the number of astrocytes generated from SVZ-derived adult NSPCs in the cortical lesion area after traumatic brain injury. Cortical brain injury resulted in rapid BMP-2 and Id3 up-regulation in the SVZ stem cell niche. Id3(-/-) adult NSPCs failed to differentiate into BMP-2-induced astrocytes, while NSPCs deficient for the Id3-controlled transcription factor E47 readily differentiated into astrocytes in the absence of BMP-2. Mechanistically, E47 repressed the expression of several astrocyte-specific genes in adult NSPCs. These results identify Id3 as the BMP-2-induced transcriptional regulator, promoting adult NSPC differentiation into astrocytes upon CNS injury and reveal a molecular link between environmental changes and NSPC differentiation in the CNS after injury.

Identification of Id1 as a downstream effector for arsenic-promoted angiogenesis via PI3K/Akt, NF-κB and NOS signaling

Exposure to arsenic is known to be a risk factor for various types of cancer. Apart from its carcinogenic activity, arsenic also shows promoting effects on angiogenesis, a crucial process for tumor growth. Yet, the mechanism underlying arsenic-induced angiogenesis is not fully understood. In this study, we aimed at investigating the involvement of inhibitor of DNA binding 1 (Id1) and the associated signal molecules in the arsenic-mediated angiogenesis. Our initial screening revealed that treatment with low concentrations of arsenic (0.5-1 μM) led to multiple cellular responses, including enhanced endothelial cell viability and angiogenic activity as well as increased protein expression of Id1. The arsenic-induced angiogenesis was suppressed in the Id1-knocked down cells compared to that in control cells. Furthermore, arsenic-induced Id1 expression and angiogenic activity were regulated by PI3K/Akt, NF-κB, and nitric oxide synthase (NOS) signaling. In summary, our current data demonstrate for the first time that Id1 mediates the arsenic-promoted angiogenesis, and Id1 may be regarded as an antiangiogenesis target for treatment of arsenic-associated cancer.

High Id1 expression, a generally negative prognostic factor, paradoxically predicts a favorable prognosis for adjuvant paclitaxel plus cisplatin therapy in surgically treated lung cancer patients

Adjuvant chemotherapy is commonly given to surgically treated non-small-cell lung cancer (NSCLC) patients. However, the prerequisite for chemotherapy needs to be scrutinized in order to maximize the benefits to patients. In this study, we observed that NSCLC cells with high Id1 protein expression were vulnerable to the treatment of paclitaxel and cisplatin. In addition, paclitaxel and cisplatin caused Id1 protein degradation through ubiquitination. In the nude mice xenograft model, the tumor growth was reduced to a large degree in the Id1-overexpressing group upon treatment with paclitaxel and cisplatin. Furthermore, immunohistochemical staining for Id1 followed by Kaplan-Meier survival analysis showed that surgically treated NSCLC patients with high Id1 expression in primary tumor tissues had better disease-free and overall survivals after adjuvant paclitaxel and cisplatin chemotherapy. In summary, our current data suggest that Id1, a generally negative prognostic factor, predicts a favorable prognosis in the case of surgically treated NSCLC patients receiving the definitive adjuvant chemotherapy. The distinct role of Id1 reported in this study may arise from the phenomenon of Id1 dependence of NSCLC cells for survival, which renders the cancer cells additionally susceptive to the adjuvant chemotherapy with paclitaxel and cisplatin.

Id1 expression in endothelial cells of the colon is required for normal response to injury

Inhibitor of DNA binding (ID)-1 is important for angiogenesis during embryogenesis and tumor development. Whether ID1 expression in endothelial cells of the colon is required for normal response to injury is unknown. We demonstrate that Id1 is up-regulated in colonic endothelial cells in an experimental model of colitis and in the inflamed mucosa of patients with inflammatory bowel disease. Because prostaglandin E2 and tumor necrosis factor-α are also elevated in colitis, we determined whether these factors could induce ID1 transcription in cultured endothelial cells. Tumor necrosis factor-α stimulated ID1 transcription via early growth response 1 protein (Egr-1). By contrast, the induction of ID1 by prostaglandin E2 was mediated by cAMP response element-binding protein (CREB). To determine whether the increased ID1 levels in the endothelial cells of inflamed mucosa were an adaptive response that modulated the severity of tissue injury, Id1 was conditionally depleted in the endothelium of mice, which sensitized the mice to more severe chemical colitis, including more severe diarrhea, bleeding, and histological injury, and shorter colon compared with control mice. Moreover, depletion of Id1 in the vasculature was associated with increased CD31(+) aggregates and increased vascular permeability in inflamed mucosa compared with those in Id1 wild-type control mice. These results suggest that endothelial ID1 up-regulation in inflamed colonic mucosa is an adaptive response that modulates the severity of tissue injury.

Different Degrees of Iodine Deficiency Inhibit Differentiation of Cerebellar Granular Cells in Rat Offspring, via BMP-Smad1/5/8 Signaling

Iodine deficiency (ID) during development results in dysfunction of the central nervous system (CNS) and affects psychomotor and motor function. It is worth noting that maternal mild and marginal ID tends to be the most common reason of preventable neurodevelopmental impairment, via a mechanism that has not been elucidated. Therefore, our aim was to study the effects of developmental mild and marginal ID on the differentiation of cerebellar granule cells (GCs) and investigate the activation of BMP-Smad1/5/8 signaling, which is crucial for the development and differentiation of cerebellum. Three developmental rat models were created by feeding dam rats with a diet deficient in iodine and deionized water supplemented with potassium iodide. Our results showed that different degrees of ID inhibited and delayed the differentiation of cerebellar GCs on postnatal day (PN) 7, PN14, and PN21. Moreover, mild and severe ID reduced the expression of BMP2 and p-Smad1/5/8, and increased the levels of Id2 on PN7, PN14, and PN21. However, marginal ID rarely altered expression of these proteins in the offspring. Our study supports the hypothesis that mild and severe ID during development inhibits the differentiation of cerebellar GCs, which may be ascribed to the down-regulation of BMP-Smad1/5/8 signaling and the overexpression of Id2. Furthermore, it was speculated that maternal marginal ID rarely affected the differentiation of cerebellar GCs in the offspring.

Inflammation-induced S100A8 activates Id3 and promotes colorectal tumorigenesis

The aberrant expression of S100A8 and S100A9 is linked to nonresolving inflammation and ultimately to carcinogenesis, whereas the underlying mechanism that allows inflammation to progress to specific cancer types remains unknown. Here, we report that S100A8 was induced by inflammation and then promoted colorectal tumorigenesis downstream by activating Id3 (inhibitor of differentiation 3). Using gene expression profiling and immunohistochemistry, we found that both S100A8 and S100A9 were upregulated in the chemically-induced colitis-associated cancer mouse model and in human colorectal cancer specimens. Furthermore, we showed that S100A8 and S100A9 acted as chemoattractant proteins by recruiting macrophages, promoting the proliferation and invasion of colon cancer cell, as well as spurring the cycle that culminates in the acceleration of cancer metastasis in a nude mouse model. S100A8 regulated colon cancer cell cycle and proliferation by inducing Id3 expression while inhibiting p21. Id3 expression was regulated by Smad5, which was directly phosphorylated by Akt1. Our study revealed a novel mechanism in which inflammation-induced S100A8 promoted colorectal tumorigenesis by acting upstream to activate the Akt1-Smad5-Id3 axis.