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

The GSK3β-β-catenin-TCF1 pathway improves naive T cell activation in old adults by upregulating miR-181a

MicroRNAs play an important role in the regulation of T cell development, activation, and differentiation. One of the most abundant microRNAs in lymphocytes is miR-181a, which controls T cell receptor (TCR) activation thresholds in thymic selection as well as in peripheral T cell responses. We previously found that miR-181a levels decline in T cells in the elderly. In this study, we identified TCF1 as a transcriptional regulator of pri-miR-181a. A decline in TCF1 levels in old individuals accounted for the reduced miR-181a expression impairing TCR signaling. Inhibition of GSK3ß restored expression of miR-181a by inducing TCF1 in T cells from old adults. GSK3ß inhibition enhanced TCR signaling to increase downstream expression of activation markers and production of IL-2. The effect involved the upregulation of miR-181a and the inhibition of DUSP6 expression. Thus, inhibition of GSK3ß can restore responses of old T cells by inducing miR-181a expression through TCF1.

Glycogen Synthase Kinase 3β in Cancer Biology and Treatment

Glycogen synthase kinase (GSK)3β is a multifunctional serine/threonine protein kinase with more than 100 substrates and interacting molecules. GSK3β is normally active in cells and negative regulation of GSK3β activity via phosphorylation of its serine 9 residue is required for most normal cells to maintain homeostasis. Aberrant expression and activity of GSK3β contributes to the pathogenesis and progression of common recalcitrant diseases such as glucose intolerance, neurodegenerative disorders and cancer. Despite recognized roles against several proto-oncoproteins and mediators of the epithelial–mesenchymal transition, deregulated GSK3β also participates in tumor cell survival, evasion of apoptosis, proliferation and invasion, as well as sustaining cancer stemness and inducing therapy resistance. A therapeutic effect from GSK3β inhibition has been demonstrated in 25 different cancer types. Moreover, there is increasing evidence that GSK3β inhibition protects normal cells and tissues from the harmful effects associated with conventional cancer therapies. Here, we review the evidence supporting aberrant GSK3β as a hallmark property of cancer and highlight the beneficial effects of GSK3β inhibition on normal cells and tissues during cancer therapy. The biological rationale for targeting GSK3β in the treatment of cancer is also discussed at length.

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.

Impaired LRP6-TCF7L2 Activity Enhances Smooth Muscle Cell Plasticity and Causes Coronary Artery Disease

Mutations in Wnt-signaling coreceptor LRP6 have been linked to coronary artery disease (CAD) by unknown mechanisms. Here, we show that reduced LRP6 activity in LRP6(R611C) mice promotes loss of vascular smooth muscle cell (VSMC) differentiation, leading to aortic medial hyperplasia. Carotid injury augmented these effects and led to partial to total vascular obstruction. LRP6(R611C) mice on high-fat diet displayed dramatic obstructive CAD and exhibited an accelerated atherosclerotic burden on LDLR knockout background. Mechanistically, impaired LRP6 activity leads to enhanced non-canonical Wnt signaling, culminating in diminished TCF7L2 and increased Sp1-dependent activation of PDGF signaling. Wnt3a administration to LRP6(R611C) mice improved LRP6 activity, led to TCF7L2-dependent VSMC differentiation, and rescued post-carotid-injury neointima formation. These findings demonstrate the critical role of intact Wnt signaling in the vessel wall, establish a causal link between impaired LRP6/TCF7L2 activities and arterial disease, and identify Wnt signaling as a therapeutic target against CAD.

Antileukemic potency of CD19-specific T cells against chemoresistant pediatric acute lymphoblastic leukemia

Adoptive therapy with chimeric antigen receptor (CAR) T cells (CART cells) has exhibited great promise in clinical trials, with efficient response correlated with CART-cell expansion and persistence. Despite extensive clinical use, the mechanisms regulating CART-cell expansion and persistence have not been completely elucidated. We have examined the antileukemia potency of CART cells targeting CD19 antigen using second-generation CAR containing a CD28 co-stimulatory domain cloned into piggyBac-transposon vector and patient-derived chemoresistant pediatric acute lymphoblastic leukemia samples. In the presence of large numbers of target cells characteristic of patients with high leukemia burden, excessive proliferation of CART cells leads to differentiation into short-lived effector cells. Transient leukemia growth delay was induced by CART-cell infusion in mice xenografted with rapidly growing CD19+ acute lymphoblastic leukemia cells and was followed by rapid CART-cell extinction. Conditioning with the hypomethylating agent 5-aza-2'-deoxycytidine-activating caspase 3 and promotion of apoptosis in leukemia cells maximized the effect of CART cells and improved CART-cell persistence. These data suggest that the clinical use of 5-aza-2'-deoxycytidine before CART cells could be considered. Coculture of leukemia cells with bone marrow stroma cells reduced target cell loss, suggesting that leukemia cell mobilization into circulation may help to remove the protective effect of bone marrow stroma and increase the efficacy of CART-cell therapy.

Wnt Signaling: Role in Regulation of Haematopoiesis

Hematopoietic stem cells (HSCs) are a unique population of bone marrow cells which are responsible for the generation of various blood cell lineages. One of the significant characteristics of these HSCs is to self-renew, while producing differentiating cells for normal hematopoiesis. Deregulation of self-renewal and differentiation leads to the hematological malignancies. Several pathways are known to be involved in the maintenance of HSC fate among which Wnt signaling is a crucial pathway which controls development and cell fate determination. Wnt signaling also plays a major role in differentiation, self-renewal and maintenance of HSCs. Wnt ligands activate three major pathways including planar cell polarity, Wnt/β-catenin and Wnt/Ca(2+). It has been shown that Wnt/β-catenin or canonical pathway regulates cell proliferation, survival and differentiation in HSCs, deregulation of this pathway leads to hematological malignancies. Wnt non-canonical pathway regulates calcium signaling and planar cell polarity. In this review, we discuss various signaling pathways induced by Wnt ligands and their potential role in hematopoiesis.

Small-molecule inhibitor of glycogen synthase kinase 3β 6-Bromoindirubin-3-oxime inhibits hematopoietic regeneration in stem cell recipient mice

Small-molecule inhibitors of glycogen synthase kinase 3β (GSK3β) have demonstrated strong anti-leukemia effects in preclinical studies. Here, we investigated the effect of GSK3β inhibitor 6-Bromoindirubin-3-oxime (BIO) previously shown to inhibit leukemia cell growth in vitro and of animal models on hematopoietic regeneration in recipients of stem cell transplant. BIO administered to immunocompromised mice transplanted with human hematopoietic stem cells inhibited human stem cell engraftment in the bone marrow (BM) and peripheral blood. BIO reduced CD34(+) progenitor cells in the BM, and primitive lymphoid progenitors re-populated host thymus at later stages post-transplant. The development of all T-cell subsets in the thymus was suppressed in BIO-treated mice. Human cell engraftment was gradually restored after discontinuation of BIO treatment; however, T-cell depletion remained until the end of experiment, which correlated with the attenuated thymic function in the host. BIO delayed CD34(+) cell expansion in stroma-supported or cytokine-only cultures. BIO treatment delayed progenitor cell divisions and induced apoptosis in cultures with sub-optimal cytokine support. In addition, BIO inhibited B- and T-cell development in co-cultures with MS5 and OP9-DL1 BM stroma cells, respectively. These data suggest that administration of GKS3β inhibitors may act to delay hematopoietic regeneration in patients who received stem cell transplant.

GSK-3β inhibition promotes early engraftment of ex vivo-expanded haematopoietic stem cells

OBJECTIVES

Umbilical cord blood (UCB) is a source of stem cells used for allogeneic transplantation, in addition to bone marrow and peripheral blood. Limited numbers of stem cells in a single UCB unit is associated with slow haematopoietic recovery and high risk of graft failure, particularly in adult patients. UCB stem cells can be expanded ex vivo; however, rapid differentiation reduces their regenerative potential. We have recently shown that Wnt/β-catenin signalling is down-regulated in ex vivo-expanded stem cells; therefore, we propose that re-activation of Wnt signalling using GSK-3β inhibition may act to improve regenerative potential of these ex vivo-expanded stem cells.

MATERIALS AND METHODS

Immunocompromised mice were employed in transplantation studies to determine stem-cell engraftment. Flow cytometry was used to phenotype the engrafted human cells. Retroviral gene transfer was used to examine the role of Myc gene up-regulated by GSK-3β inhibition, in ex vivo-expanded stem cells.

RESULTS

Treatment with GSK-3β inhibitor, 6-bromoindirubin 3'-oxime (BIO) improved early human cell engraftment in the mice and elevated the numbers of myeloid progenitor cells in cytokine-stimulated culture. BIO up-regulated β-catenin and c-myc in ex vivo-expanded stem cells. Ectopic expression of Myc acted to increase clonogenic potential and to delay differentiation of haematopoietic progenitor cells, suggesting the potential mechanism to improve regenerative potential of ex vivo-expanded grafts.

CONCLUSIONS

Pharmacological inhibition of GSK-3β provided a novel approach to improve early engraftment of ex vivo-expanded haematopoietic progenitor cells.