Beta-catenin expression enhances IL-7 receptor signaling in thymocytes during positive selection

Inhibition of WNT signaling by conjugated microRNA nano-carriers: A new therapeutic approach for treating triple-negative breast cancer a perspective review

Triple-Negative Breast Cancer is the most aggressive form and accounts the 15%-25% of all breast cancer. Receptors are absent in triple-negative breast cancer, which makes them unresponsive to the current hormonal therapies. The patients with TNBC are left with the option of cytotoxic chemotherapy. The Wnt pathways are connected to cancer, and when activated, they result in mammary hyperplasia and tumors. The tumor suppressor microRNAs can block tumor cell proliferation, invasion, and migration, lead to cancer cell death, and are also known to down-regulate the WNT signaling. Nanoparticles with microRNA have been seen to be more effective when compared with their single release. In this review, we have tried to understand how Wnt signaling plays a crucial role in TNBC, EMT, metastasis, anti-drug resistance, and regulation of Wnt by microRNA. The role of nano-carriers in delivering micro-RNA. The clinical biomarkers, including the present state-of-the-art, involve novel pathways of Wnt.

Axin2/Conductin Is Required for Normal Haematopoiesis and T Lymphopoiesis

The development of T lymphocytes in the thymus and their stem cell precursors in the bone marrow is controlled by Wnt signaling in strictly regulated, cell-type specific dosages. In this study, we investigated levels of canonical Wnt signaling during hematopoiesis and T cell development within the Axin2-mTurquoise2 reporter. We demonstrate active Wnt signaling in hematopoietic stem cells (HSCs) and early thymocytes, but also in more mature thymic subsets and peripheral T lymphocytes. Thymic epithelial cells displayed particularly high Wnt signaling, suggesting an interesting crosstalk between thymocytes and thymic epithelial cells (TECs). Additionally, reporter mice allowed us to investigate the loss of Axin2 function, demonstrating decreased HSC repopulation upon transplantation and the partial arrest of early thymocyte development in Axin2^Tg/Tg full mutant mice. Mechanistically, loss of Axin2 leads to supraphysiological Wnt levels that disrupt HSC differentiation and thymocyte development.

Human Wnt/β-Catenin Regulates Alloimmune Signaling during Allogeneic Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is one of the most widely applied forms of adoptive immunotherapy for the treatment of hematological malignancies. Detrimental graft-versus-host disease (GVHD), but also beneficial graft-versus-leukemia (GVL) effects occurring after allo-HSCT are largely mediated by alloantigen-reactive donor T cells in the graft. Separating GVHD from GVL effects is a formidable challenge, and a greater understanding of donor T cell biology is required to accomplish the uncoupling of GVHD from GVL. Here, we evaluated the role of β-catenin in this process. Using a unique mouse model of transgenic overexpression of human β-catenin (Cat-Tg) in an allo-HSCT model, we show here that T cells from Cat-Tg mice did not cause GVHD, and surprisingly, Cat-Tg T cells maintained the GVL effect. Donor T cells from Cat-Tg mice exhibited significantly lower inflammatory cytokine production and reduced donor T cell proliferation, while upregulating cytotoxic mediators that resulted in enhanced cytotoxicity. RNA sequencing revealed changes in the expression of 1169 genes for CD4, and 1006 genes for CD8⁺ T cells involved in essential aspects of immune response and GVHD pathophysiology. Altogether, our data suggest that β-catenin is a druggable target for developing therapeutic strategies to reduce GVHD while preserving the beneficial GVL effects following allo-HSCT treatment.

Wnt Signaling in the Regulation of Immune Cell and Cancer Therapeutics

Wnt signaling is one of the important pathways to play a major role in various biological processes, such as embryonic stem-cell development, tissue regeneration, cell differentiation, and immune cell regulation. Recent studies suggest that Wnt signaling performs an essential function in immune cell modulation and counteracts various disorders. Nonetheless, the emerging role and mechanism of action of this signaling cascade in immune cell regulation, as well as its involvement in various cancers, remain debatable. The Wnt signaling in immune cells is very diverse, e.g., the tolerogenic role of dendritic cells, the development of natural killer cells, thymopoiesis of T cells, B-cell-driven initiation of T-cells, and macrophage actions in tissue repair, regeneration, and fibrosis. The purpose of this review is to highlight the current therapeutic targets in (and the prospects of) Wnt signaling, as well as the potential suitability of available modulators for the development of cancer immunotherapies. Although there are several Wnt inhibitors relevant to cancer, it would be worthwhile to extend this approach to immune cells.

The Construction and Analysis of ceRNA Network and Patterns of Immune Infiltration in Mesothelioma With Bone Metastasis

Background: Mesothelioma is a rare and aggressive tumor. Bone metastasis often occurs in the later stages of this disease along with poor quality of life. Thus, it is important to explore the tumorigenesis and bone metastasis mechanism of invasive mesothelioma. For this purpose, we established two nomograms based on tumor-infiltrating immune cells and ceRNA networks to describe the molecular immunity and the clinical prediction of mesothelioma patients with bone metastasis.

Method: The expression profiles of mRNAs, lncRNAs, and miRNAs of 87 primary mesotheliomas were obtained from the TCGA database; there were four patients with bone metastasis and 83 patients without. We constructed a ceRNAs network based on the differentially expressed RNAs between mesothelioma and bone metastasis. CIBERSORT was used to distinguish 22 immune cell types from the tumor transcriptomes. Kaplan–Meier survival analysis and the Cox proportional hazards model were used to evaluate the prognostic value of each factor. Prognosis-associated immune cells and ceRNAs were applied to establish prediction nomograms. The receiver operating characteristic curves (ROC) and calibration curves were utilized to assess the discrimination and accuracy of the nomogram.

Results: Differential analysis revealed that 20 lncRNAs, 15 miRNAs, and 230 mRNAs were significantly different in mesothelioma samples vs. bone metastasis samples. We constructed the ceRNA network to include 10 protein-coding mRNAs, 8 lncRNAs, and 10 miRNAs. Nine of 28 ceRNAs were found to be significant in the Kaplan–Meier analysis. Out of the 22 cell types, the fraction of dendritic cells resting (P = 0.018) was significantly different between the bone metastasis group and the non-bone metastasis group. The ROC and the calibration curves, based on ceRNA networks and tumor-infiltrating immune cells, respectively, suggested acceptable accuracy (AUC of 3-year survival: 0.827, AUC of 5-year survival: 0.840; AUC of 3-year survival: 0.730; AUC of 5-year survival: 0.753). Notably, based on the co-expression patterns between ceRNAs and Immune cells, we found that the hsa-miR-582-5p, CASP9, dendritic cells resting, ANIX2, T cells CD8, and T cells CD4 memory resting might be associated with the mesothelioma bone metastasis.

Conclusion: Based on ceRNA networks and patterns of immune infiltration, our study provided a valid bioinformatics basis in order to explore the molecular mechanism and predict the possibility of mesothelioma bone metastasis.

Canonical and Non-Canonical Wnt Signaling in Immune Cells

Cell differentiation, proliferation, and death are vital for immune homeostasis. Wnt signaling plays essential roles in processes across species. The roles of Wnt signaling proteins and Wnt ligands have been studied in the past, but the context-dependent mechanisms and functions of these pathways in immune responses remain unclear. Recent findings regarding the role of Wnt ligands and Wnt signaling in immune cells and their immunomodulatory mechanisms suggest that Wnt ligands and signaling are significant in regulating immune responses. We introduce recent key findings and future perspectives on Wnt ligands and their signaling pathways in immune cells as well as the immunological roles and functions of Wnt antagonists.

Wnt signaling in triple-negative breast cancer

Wnt signaling regulates a variety of cellular processes, including cell fate, differentiation, proliferation and stem cell pluripotency. Aberrant Wnt signaling is a hallmark of many cancers. An aggressive subtype of breast cancer, known as triple-negative breast cancer (TNBC), demonstrates dysregulation in canonical and non-canonical Wnt signaling. In this review, we summarize regulators of canonical and non-canonical Wnt signaling, as well as Wnt signaling dysfunction that mediates the progression of TNBC. We review the complex molecular nature of TNBC and the emerging therapies that are currently under investigation for the treatment of this disease.

Caught in a Wnt storm: Complexities of Wnt signaling in hematopoiesis

The Wnt signaling pathway is an evolutionary conserved pathway that is involved in the development of almost every organ system in the body and provides self-renewal signals for most, if not all, adult stem cell systems. In recent years, this pathway has been studied by various research groups working on hematopoietic stem cells, resulting in contradicting conclusions. Here, we discuss and interpret the results of these studies and propose that Wnt dosage, the source of hematopoietic stem cells, and interactions with other pathways explain these disparate results.

A critical role for the regulated wnt-myc pathway in naive T cell survival

Wnt signaling is involved in T cell development, activation, and differentiation. However, the role for Wnt signaling in mature naive T cells has not been investigated. In this article, we report that activation of Wnt signaling in T cell lineages by deletion of the Apc (adenomatous polyposis coli) gene causes spontaneous T cell activation and severe T cell lymphopenia. The lymphopenia is the result of rapid apoptosis of newly exported, mature T cells in the periphery and is not due to defects in thymocyte development or emigration. Using chimera mice consisting of both wild-type and Apc-deficient T cells, we found that loss of naive T cells is due to T cell intrinsic dysregulation of Wnt signaling. Because Apc deletion causes overexpression of the Wnt target gene cMyc, we generated mice with combined deletion of the cMyc gene. Because combined deletion of cMyc and Apc attenuated T cell loss, cMyc overexpression is partially responsible for spontaneous T cell apoptosis and lymphopenia. Cumulatively, our data reveal a missing link between Wnt signaling and survival of naive T cells.

Systematic analysis of blood cell transcriptome in end-stage chronic respiratory diseases

Background

End-stage chronic respiratory diseases (CRD) have systemic consequences, such as weight loss and susceptibility to infection. However the mechanisms of such dysfunctions are as yet poorly explained. We hypothesized that the genes putatively involved in these mechanisms would emerge from a systematic analysis of blood mRNA profiles from pre-transplant patients with cystic fibrosis (CF), pulmonary hypertension (PAH), and chronic obstructive pulmonary disease (COPD).

Methods

Whole blood was first collected from 13 patients with PAH, 23 patients with CF, and 28 Healthy Controls (HC). Microarray results were validated by quantitative PCR on a second and independent group (7PAH, 9CF, and 11HC). Twelve pre-transplant COPD patients were added to validate the common signature shared by patients with CRD for all causes. To further clarify a role for hypoxia in the candidate gene dysregulation, peripheral blood mononuclear cells from HC were analysed for their mRNA profile under hypoxia.

Results

Unsupervised hierarchical clustering allowed the identification of 3 gene signatures related to CRD. One was common to CF and PAH, another specific to CF, and the final one was specific to PAH. With the common signature, we validated T-Cell Factor 7 (TCF-7) and Interleukin 7 Receptor (IL-7R), two genes related to T lymphocyte activation, as being under-expressed. We showed a strong impact of the hypoxia on modulation of TCF-7 and IL-7R expression in PBMCs from HC under hypoxia or PBMCs from CRD. In addition, we identified and validated genes upregulated in PAH or CF, including Lectin Galactoside-binding Soluble 3 and Toll Like Receptor 4, respectively.

Conclusions

Systematic analysis of blood cell transcriptome in CRD patients identified common and specific signatures relevant to the systemic pathologies. TCF-7 and IL-7R were downregulated whatever the cause of CRD and this could play a role in the higher susceptibility to infection of these patients.

An overview of the intrathymic intricacies of T cell development

The generation of a functional and diverse repertoire of T cells occurs in the thymus from precursors arriving from the bone marrow. In this article, we introduce the various stages of mouse thymocyte development and highlight recent work using various in vivo, and, where appropriate, in vitro models of T cell development that led to discoveries in the regulation afforded by transcription factors and receptor-ligand signaling pathways in specifying, maintaining, and promoting the T cell lineage and the production of T cells. This review also discusses the role of the thymic microenvironment in providing a niche for the successful development of T cells. In particular, we focus on advances in Notch signaling and developments in Notch ligand interactions in this process.

GSK-3β inhibition preserves naive T cell phenotype in bone marrow reconstituted mice

Hematopoietic stem cell transplantation (HSCT) is used in the treatment of hematologic and nonhematologic disorders. PostHSCT immunologic reconstitution is a critical component for successful outcome. Pretransplant conditioning impairs thymic function, leading to delayed T cell regeneration. Thymus-independent T cell expansion is associated with defective generation of naive T cells and memory T cell skewing, resulting in decreased diversity in the T cell repertoire, thus attenuating the immune responses and increasing the risk of opportunistic infections and leukemia relapse. Wingless (Wnt) signaling has been identified as an important regulator of T cell development and function. Activated Wnt signaling inhibited differentiation of mature T cells in transgenic mouse models. The effect of Wnt activation on T cell regeneration following HSCT was not investigated. In this study, we demonstrate that the GSK-3β inhibitor 6-bromoindirubin 3'-oxime (BIO) activates Wnt/β-catenin signaling, elevates the proportion of naive T cells, and delays T cell differentiation during homeostatic T cell expansion in lymphodepleted mice transplanted with human hematopoietic stem cells. In vitro BIO-treatment promoted naive T cell expansion following mitogenic stimulation and improved proliferative responses of T cells to allogeneic stimuli. Treatment with BIO acts to expand the IL7Rα(+) subset of naive T cells, suggesting the potential mechanism driving T cell expansion during IL-7-dependent T cell proliferation. BIO downregulated expression of genes activated during effector cell differentiation and preserved naive T cell gene expression. We propose that administration of GSK-3β inhibitor increases the potency of T cells in recipients of HSCT by expansion of naive T cell subsets with a diverse T cell receptor repertoire.

Regulatory mechanisms of thymus and T cell development

The thymus is a central hematopoietic organ which produces mature T lymphocytes with diverse antigen specificity. During development, the thymus primordium is derived from the third pharyngeal endodermal pouch, and then differentiates into cortical and medullary thymic epithelial cells (TECs). TECs represent the primary functional cell type that forms the unique thymic epithelial microenvironment which is essential for intrathymic T-cell development, including positive selection, negative selection and emigration out of the thymus. Our understanding of thymopoiesis has been greatly advanced by using several important animal models. This review will describe progress on the molecular mechanisms involved in thymus and T cell development with particular focus on the signaling and transcription factors involved in this process in mouse and zebrafish.

β-catenin/TCF-1 pathway in T cell development and differentiation

T cells must undergo two critical differentiation processes before they become competent effectors that can mediate actual immune responses. Progenitor T cells undergo defined stages of differentiation in the thymus, which include positive and negative selection, to generate a repertoire of T cells that will respond to foreign but not self antigens. When these immunocompetent T cells first migrate out of thymus into peripheral lymphoid tissues, they are naïve and are unable to mediate immune responses. However, upon antigen encounter, peripheral CD4+ naïve T cells undergo another differentiation process to become armed effector T cells including Th1, Th2, Th17 or regulatory T cells, all of which are capable of regulating immune responses. A canonical Wnt/β-catenin/T cell factor (TCF) pathway has been shown to regulate T cell differentiation in both the thymus and in peripheral lymphoid tissues. Dysfunction of this pathway at any stage of T cell differentiation could lead to severe autoimmunity including experimental autoimmune encephalomyelitis or immune deficiency. Understanding the role played by β-catenin/TCF-1 in T cell differentiation will facilitate our understanding of the mechanisms that regulate T cell function and assist in identifying novel therapy targets for treating both autoimmune and immune diseases. Therefore, in this review, we will focus on the function of β-catenin/TCF-1 pathway in the regulation of thymic and peripheral T cell differentiation processes.

IL-7: the global builder of the innate lymphoid network and beyond, one niche at a time

The development and homeostasis of adaptive and innate lymphocytes is dependent on the stromal cytokine IL-7. The initial priming of immune responses to pathogenic challenges is executed by innate lymphoid cells (ILCs) with programmed capacity to rapidly secrete effector cytokines. How ILCs are controlled by IL-7 in distinct anatomical locale has evolved into a more complex problem as IL-7 receptor is not only expressed on ILCs, but also on surrounding neighbors, including vascular endothelium and mesenchymal cells that compete for limiting IL-7. For the generation of γδ T and B cells IL-7 is required for the production of antigen receptors, and it is likely that IL-7 performs critical function in facilitating ILC effector programming in addition to its regulatory actions on cell survival and proliferation. Most of our current understanding of the highly calibrated regulatory circuits of IL-7 function and IL-7 receptor signaling has derived from studies of adaptive, conventional lymphocytes. Here we highlight recent advances in mapping the gene circuits and cellular interactions that regulate temporospatial activities of IL-7 in diverse macro and micro niches that have direct relevance to deciphering the sphere of impact of IL-7 on ILC differentiation.

T-cell factor 1 is a gatekeeper for T-cell specification in response to Notch signaling

Although transcriptional programs associated with T-cell specification and commitment have been described, the functional hierarchy and the roles of key regulators in structuring/orchestrating these programs remain unclear. Activation of Notch signaling in uncommitted precursors by the thymic stroma initiates the T-cell differentiation program. One regulator first induced in these precursors is the DNA-binding protein T-cell factor 1 (Tcf-1), a T-cell-specific mediator of Wnt signaling. However, the specific contribution of Tcf-1 to early T-cell development and the signals inducing it in these cells remain unclear. Here we assign functional significance to Tcf-1 as a gatekeeper of T-cell fate and show that Tcf-1 is directly activated by Notch signals. Tcf-1 is required at the earliest phase of T-cell determination for progression beyond the early thymic progenitor stage. The global expression profile of Tcf-1-deficient progenitors indicates that basic processes of DNA metabolism are down-regulated in its absence, and the blocked T-cell progenitors become abortive and die by apoptosis. Our data thus add an important functional relationship to the roadmap of T-cell development.

TCF1 and beta-catenin regulate T cell development and function

T cell factor-1 (TCF1) critically regulates T cell development. However, signals that control TCF1 function in developing and mature T cells remain unknown. TCF1 along with beta-catenin activates gene transcription and in cooperation with Groucho family of proteins mediates gene repression. It has been established that the beta-catenin-dependent gene expression is often downstream of the canonical Wnt signaling pathway. We have genetically manipulated the beta-catenin gene and generated mutant mice that have shown an essential role for beta-catenin and TCF1 during pre-T cell receptor (TCR) and TCR-dependent stages of T cell development. We have also demonstrated a function for TCF1 and beta-catenin downstream of TCR signaling in the differentiation of mature CD4 T cells into T helper lineages.

Gads-deficient thymocytes are blocked at the transitional single positive CD4+ stage

Positive selection of T-cell precursors is the process by which a diverse T-cell repertoire is established. Positive selection begins at the CD4(+)CD8(+) double positive (DP) stage of development and involves at least two steps. First, DP thymocytes down-regulate CD8 to become transitional single positive (TSP) CD4(+) thymocytes. Then, cells are selected to become either mature single positive CD4(+) or mature single positive CD8(+) thymocytes. We sought to define the function of Gads during the two steps of positive selection by analyzing a Gads-deficient mouse line. In Gads(+/+) mice, most TSP CD4(+) thymocytes are TCR(hi)Bcl-2(hi)CD69(+), suggesting that essential steps in positive selection occurred in the DP stage. Despite that Gads(-/-) mice could readily generate TSP CD4(+) thymocytes, many Gads(-/-) TSP CD4(+) cells were TCR(lo)Bcl-2(lo)CD69(-), suggesting that Gads(-/-) cells proceeded to the TSP CD4(+) stage prior to being positively selected. These data suggest that positive selection is not a prerequisite for the differentiation of DP thymocytes into TSP CD4(+) thymocytes. We propose a model in which positive selection and differentiation into the TSP CD4(+) stage are separable events and Gads is only required for positive selection.

The canonical Wnt signaling pathway plays an important role in lymphopoiesis and hematopoiesis

The evolutionarily conserved canonical Wnt-beta-catenin-T cell factor (TCF)/lymphocyte enhancer binding factor (LEF) signaling pathway regulates key checkpoints in the development of various tissues. Therefore, it is not surprising that a large body of gain-of-function and loss-of-function studies implicate Wnt-beta-catenin signaling in lymphopoiesis and hematopoiesis. In contrast, recent papers have reported that Mx-Cre-mediated conditional deletion of beta-catenin and/or its homolog gamma-catenin (plakoglobin) did not impair hematopoiesis or lymphopoiesis. However, these studies also report that TCF reporter activity remains active in beta-catenin- and gamma-catenin-deficient hematopoietic stem cells and all cells derived from these precursors, indicating that the canonical Wnt signaling pathway was not abrogated. Therefore, these studies in fact show that the canonical Wnt signaling pathway is important in hematopoiesis and lymphopoiesis, even though the molecular basis for the induction of the reporter activity is currently unknown. In this perspective, we provide a broad background to the field with a discussion of the available data and create a framework within which the available and future studies may be evaluated.

WNT signalling in the immune system: WNT is spreading its wings

WNT proteins are secreted morphogens that are required for basic developmental processes, such as cell-fate specification, progenitor-cell proliferation and the control of asymmetric cell division, in many different species and organs. In blood and immune cells, WNT signalling controls the proliferation of progenitor cells and might also affect the cell-fate decisions of stem cells. Recent studies indicate that WNT proteins also regulate effector T-cell development, regulatory T-cell activation and dendritic-cell maturation. WNT signalling seems to function as a universal mechanism in leukocytes to establish a pool of undifferentiated cells for further selection, effector-cell maturation and terminal differentiation. WNT signalling is therefore subject to strict molecular control, and dysregulated WNT signalling is implicated in the development of haematological malignancies.

ICAT expression disrupts beta-catenin-TCF interactions and impairs survival of thymocytes and activated mature T cells

T cell factor (TCF) family of transcription factors and beta-catenin critically regulate T cell development as demonstrated by the deletion of the tcf gene, which results in a block early in development that becomes complete in mice bearing tcf/lef double deletion. However, the role of beta-catenin, a major TCF cofactor, remains controversial. To directly address this, we have generated transgenic mice expressing Inhibitor of beta-catenin and TCF (ICAT), a naturally occurring inhibitor that specifically disrupts TCF and beta-catenin interactions. In this report, we demonstrate that disrupting the interaction of beta-catenin with TCF renders adult thymocytes and activated T cells highly susceptible to apoptosis. In contrast to previously reported observations during fetal thymocyte development, these data show that in adult mice, survival and not differentiation of thymocytes, depends on transcription by TCF and beta-catenin. Indeed, we demonstrate that expression of ICAT impedes thymocyte survival by reducing the expression of Bcl(xL) in thymocytes below a critical threshold. Survival of activated mature T cells was also impaired due to diminished expression of activation-induced Bcl(xL). Accordingly, expression of transgenic Bcl-2 rescued activated ICAT-Tg CD4 T cells from apoptosis. Thus, disruption of TCF-beta-catenin interactions specifically impairs the survival of thymocytes and activated T cells.

Administration of two macrophage-derived interferon-gamma-inducing factors (IL-12 and IL-15) induces a lethal systemic inflammatory response in mice that is dependent on natural killer cells but does not require interferon-gamma

Activation of macrophages by microbes results in the rapid production of monokines (e.g., interleukin-12 (IL-12), IL-15, and IL-18), which induce production of interferon-gamma (IFN-gamma) by natural killer (NK) cells. We examined the effects of administering IL-15 in combination with IL-12 in a murine toxicity model to determine how these two cytokines might contribute to the inflammatory state that accompanies infectious processes. The daily, simultaneous administration of IL-15 (3 x 10(5)U) and IL-12 (1 microg) to normal mice resulted in shock and 100% mortality within 3-7 days, whereas minimal toxicity was observed following the administration of IL-15 or IL-12 alone. Mice treated with IL-15 plus IL-12 exhibited lesions of the gastrointestinal tract, elevated serum levels of acute phase reactants and pro-inflammatory cytokines, and NK cell apoptosis. Neutralization of IFN-gamma, TNF-alpha, and IL-1beta was not protective in cytokine-treated mice, however, toxicity and death could be completely abrogated by depletion of NK cells. Mice deficient in the STAT4 transcription factor also exhibited complete protection while mice deficient in IFN-gamma or its downstream mediator, STAT1, did not. These findings suggest that cytokine- stimulated NK cells are able to promote systemic inflammation via the induction of STAT4-responsive genes other than IFN-gamma or TNF-alpha.