Binsheng Wang

Galectin-3 mediates bone marrow microenvironment-induced drug resistance in acute leukemia cells via Wnt/β-catenin signaling pathway

BackgroundAcute leukemia is currently the major cause of death in hematological malignancies. Despite the rapid development of new therapies, minimal residual disease (MRD) continues to occur and leads to poor outcomes. The leukemia niche in the bone marrow microenvironment (BMM) is thought to be responsible for such MRD development, which can lead to leukemia drug resistance and disease relapse. Consequently further investigation into the way in which the leukemia niche interacts with acute leukemia cells (ALCs) and development of strategies to block the underlying process are expected to improve disease prognosis. Recent studies indicated that galectin-3 (gal-3) might play a pivotal role in this process. Thus we aimed to elucidate the exact role played by gal-3 in this process and clarify its mechanism of action.MethodsWe used human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) to mimic the leukemia BMM in vitro, and investigated their effects on drug resistance of ALCs and the possible mechanisms involved, with particular emphasis on the role of gal-3.ResultsIn our study, we demonstrated that hBM-MSCs induced gal-3 up-regulation, promoting β-catenin stabilization and thus activating the Wnt/β-catenin signaling pathway in ALCs, which is critical in cytotoxic drug resistance of leukemia. This effect could be reversed by addition of gal-3 short hairpin RNA (shRNA). We also found that up-regulation of gal-3 promoted Akt and glycogen synthase kinase (GSK)-3β phosphorylation, thought to constitute a cross-bridge between gal-3 and Wnt signaling.ConclusionsOur results suggest that gal-3, a key factor mediating BMM-induced drug resistance, could be a novel therapeutic target in acute leukemia.

Association between DNMT3A Mutations and Prognosis of Adults with De Novo Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis

Background DNA methyltransferase 3A (DNMT3A) mutations were considered to be independently associated with unfavorable prognosis in adults with de novo acute myeloid leukemia (AML), however, there are still debates on this topic. Here, we aim to further investigate the association between DNMT3A mutations and prognosis of patients with AML. Methods Eligible studies were identified from several data bases including PubMed, Embase, Web of Science, ClinicalTrials and the Cochrane Library (up to June 2013). The primary endpoint was overall survival (OS), while relapse-free survival (RFS) and event-free survival (EFS) were chosen as secondary endpoints. If possible, we would pool estimate effects (hazard ratio [HR] with 95% confidence interval[CI]) of outcomes in random and fixed effects models respectively. Results That twelve cohort studies with 6377 patients exploring the potential significance of DNMT3A mutations on prognosis were included. Patients with DNMT3A mutations had slightly shorter OS (HR = 1.60; 95% CI, 1.31–1.95; P<0.001), as compared to wild-type carriers. Among the patients younger than 60 years of age, DNMT3A mutations predicted a worse OS (HR = 1.84; 95% CI, 1.36–2.50; P<0.001). In addition, mutant DNMT3A predicted inferior OS (HR = 2.30; 95% CI, 1.78–2.97; P = 0.862) in patients with unfavorable genotype abnormalities. Similar results were also found in some other subgroups. However, no significant prognostic value was found on OS (HR = 1.40; 95% CI, 0.98–1.99; P = 0.798) in the favorable genotype subgroup. Similar results were found on RFS and EFS under different conditions. Conclusions DNMT3A mutations have slightly but significantly poor prognostic impact on OS, RFS and EFS of adults with de novo AML in total population and some specific subgroups.

Rapamycin interacts synergistically with idarubicin to induce T-leukemia cell apoptosis in vitro and in a mesenchymal stem cell simulated drug-resistant microenvironment via Akt/mammalian target of rapamycin and extracellular signal-related kinase signaling pathways.

Abstract T-cell acute lymphoblastic leukemias (T-ALLs) are clonal lymphoid malignancies with a poor prognosis, and still a lack of effective treatment. Here we examined the interactions between the mammalian target of rapamycin (mTOR) inhibitor rapamycin and idarubicin (IDA) in a series of human T-ALL cell lines Molt-4, Jurkat, CCRF-CEM and CEM/C1. Co-exposure of cells to rapamycin and IDA synergistically induced T-ALL cell growth inhibition and apoptosis mediated by caspase activation via the intrinsic mitochondrial pathway and extrinsic pathway. Combined treatment with rapamycin and IDA down-regulated Bcl-2 and Mcl-1, and inhibited the activation of phosphoinositide 3-kinase (PI3K)/mTOR and extracellular signal-related kinase (ERK). They also played synergistic pro-apoptotic roles in the drug-resistant microenvironment simulated by mesenchymal stem cells (MSCs) as a feeder layer. In addition, MSCs protected T-ALL cells from IDA cytotoxicity by up-regulating ERK phosphorylation, while rapamycin efficiently reversed this protective effect. Taken together, we confirm the synergistic antitumor effects of rapamycin and IDA, and provide an insight into the potential future clinical applications of combined rapamycin–IDA regimens for treating T-cell malignancies.

Bone marrow mesenchymal stromal cells affect the cell cycle arrest effect of genotoxic agents on acute lymphocytic leukemia cells via p21 down-regulation

The effect of bone marrow microenvironment on the cell cycle of acute lymphocytic leukemia (ALL) and the underlying mechanism has not been elucidated. In this study, we found that in normal condition, bone marrow mesenchymal stromal cells (BM-MSCs) had no significant effect on the cell cycle and apoptosis of ALL; in the condition when the cell cycle of ALL was blocked by genotoxic agents, BM-MSCs could increase the S-phase cell ratio and decrease the G2/M phase ratio of ALL. Besides, BM-MSCs could protect ALL cells from drug-induced apoptosis. Then, we proved that BM-MSCs affect the cell cycle arrest effect of genotoxic agents on ALL cells via p21 down-regulation. Moreover, our results indicated that activation of Wnt/β-catenin and Erk pathways might be involved in the BM-MSC-induced down-regulation of p21 in ALL cells. Targeting microenvironment-related signaling pathway may therefore be a potential novel approach for ALL therapy.

Phenotypical and Functional Characterization of Bone Marrow Mesenchymal Stem Cells in Patients with Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) is a critical complication after allogeneic hematopoietic stem cell transplantation. The conditioning therapy has been involved in the impairment of bone marrow (BM) mesenchymal stem/stromal cells (MSCs). However, the potential implication of MSCs in the pathophysiology of cGVHD has not been investigated. We analyzed expanded MSCs from patients with cGVHD and compared them with those from transplantation patients without cGVHD. The MSCs from both groups were of host origin and their reserves were comparable. They showed similar morphology, immunophenotype, population doubling times, self-renewal capacity, differentiation, and migration potential. The immunomodulatory potential of the 2 groups was also identical, they were both capable of inhibiting phytohemagglutinin-activated peripheral blood mononuclear cells (PBMCs) proliferation and inducing regulatory T cells after coculturing with CD4(+) T cells, and the immunosuppressive factors were secreted similarly in both MSCs whether in normal culture or coculture with PBMCs. No significant differences were observed in the cellular senescence and apoptosis between 2 groups. In addition, MSCs from patients with cGVHD displayed normal phenotype and function compared with their counterparts from healthy donors, although reduced frequency in BM mononuclear cell fraction was observed in these patients. Taken together, our results suggest that MSCs do not seem to contribute to the pathogenesis of cGVHD and indicate the feasibility of autologous cell therapy in patients who are not completely responding to standard immunosuppressive therapy for cGVHD.

Dasatinib promotes the potential of proliferation and antitumor responses of human γδT cells in a long-term induction ex vivo environment.

Dasatinib promotes the potential of proliferation and antitumor responses of human γδT cells in a long-term induction ex vivo environment

γδ T cell and other immune cells crosstalk in cellular immunity.

γδ T cells have been recognized as effectors with immunomodulatory functions in cellular immunity. These abilities enable them to interact with other immune cells, thus having the potential for treatment of various immune-mediated diseases with adoptive cell therapy. So far, the interactions between γδ T cell and other immune cells have not been well defined. Here we will discuss the interactivities among them and the perspective on γδ T cells for their use in immunotherapy could be imagined. The understanding of the crosstalk among the immune cells in immunopathology might be beneficial for the clinical application of γδ T cell.

A Member of the Nuclear Receptor Superfamily, Designated as NR2F2, Supports the Self-Renewal Capacity and Pluripotency of Human Bone Marrow-Derived Mesenchymal Stem Cells

Mesenchymal stem cells are characterized with self-renewal capacity and pluripotency. NR2F2 is a nuclear receptor that has been detected in the mesenchymal compartment of developing organs. However, whether NR2F2 plays a role in the stemness maintenance of mesenchymal stem cells has not been explored yet. In this study, we investigated the function of NR2F2 in bone marrow-derived mesenchymal stem cells via shRNA-mediated knock-down of NR2F2. The suppression of NR2F2 impaired the colony-forming efficacy of mesenchymal stem cells. The inhibition of colony-forming capacity may be attributed to the acceleration of senescence through upregulation of P21 and P16. The downregulation of NR2F2 also suppressed both osteogenic and adipogenic differentiation processes. In conclusion, NR2F2 plays an important role in the stemness maintenance of bone marrow-derived mesenchymal stem cells.

mTOR inhibition improves the immunomodulatory properties of human bone marrow mesenchymal stem cells by inducing COX-2 and PGE 2

BackgroundBone marrow mesenchymal stem cells (MSCs) are promising candidates for the treatment of various inflammatory disorders due to their profound immunomodulatory properties. However, the immunosuppressive capacity of MSCs needs activation by an inflammatory microenvironment, which may negatively impact the therapeutic effect because of increased immunogenicity. Here we explore the role of mammalian target of rapamycin (mTOR) signaling on the immunosuppressive capacity of MSCs, and its impact on immunogenicity in the inflammatory microenvironment.MethodsHuman bone marrow MSCs were cocultured with activated human peripheral blood mononuclear cells, CD4+ T cells, and mouse splenocytes to evaluate the immunosuppressive function. Immunosuppressive factors were assessed by quantitative real-time polymerase chain reaction (PCR), Western blot, and enzyme-linked immunosorbent assay (ELISA). The expression of major histocompatibility complex (MHC) was detected by flow cytometry. Short hairpin (sh)RNA was used to downregulate tuberous sclerosis complex (TSC)2, TSC1, and cyclooxygenase (COX)-2 in MSCs.ResultsInhibition of mTOR signaling using rapamycin enhanced the immunosuppressive functions of MSCs, while prolonged exposure to rapamycin did not. The enhancement of the immunosuppressive function was independent of the inflammatory microenvironment, and occurred mainly through the upregulation of COX-2 and prostaglandin-E2 (PGE2) expression. Furthermore, mTOR inhibition did not impact the immunogenicity of MSCs. However, the upregulated expression of MHC class II molecules by interferon (IFN)-γ was attenuated by mTOR inhibition, whereas TSC2 knockdown had the opposite effect.ConclusionsThese results reveal that the mTOR signaling pathway regulates MSC immunobiology, and short-term exposure to rapamycin could be a novel approach to improve the MSC-based therapeutic effect.

Hydroxychloroquine sensitizes chronic myeloid leukemia cells to Vγ9Vδ2 T cell-mediated lysis independent of autophagy

Hydroxychloroquine (HCQ) is the only autophagy inhibitor in clinical use and it has shown great potential in treating chronic myeloid leukemia (CML). By inhibiting autophagy, HCQ enhances the anti-CML efficiency of chemotherapy. In the present study, we demonstrated that HCQ sensitized CML cells to Vγ9Vδ2 T cell-mediated lysis. HCQ inhibited autophagy in CML cells, but the sensitizing effects of HCQ were autophagy-independent. Since the sensitization was not mimicked by ATG7 knockdown and even occurred in the absence of ATG7. We revealed that in a time-dependent manner HCQ induced the expression of NKG2D ligand ULBP4 on the surface of CML cells. This marks the leukemia cell for recognition by Vγ9Vδ2 T cells. Blocking the interaction of NKG2D with its ligands deleted the sensitizing effects of HCQ. In addition, we showed that HCQ did not affect the synthesis or degradation of ULBP4, but induced the translocation of ULBP4 from the cytoplasm to the cell membrane. Our results uncovered a previously unknown mechanism for HCQ in CML treatment that underlines the ability of HCQ to modulate the immune visibility of CML cells, and pave the way to the development of new combination treatments with HCQ and Vγ9Vδ2 T cells.