Endogenous stromal cell-derived factor-1 (CXCL12) supports autonomous growth of acute myeloid leukemia cells

Serum stromal cell-derived factor 1α as a prognostic indicator in elderly patients with acute myeloid leukemia receiving CAG-based chemotherapy

Background

Stromal-cell-derived factor 1 (SDF-1) plays a crucial role in hematopoiesis and has been implicated in acute myeloid leukemia (AML) pathogenesis. Understanding its relationship with chemotherapy outcomes could lead to improved therapeutic approaches for elderly AML patients.

Methods

This study retrospectively analyzed the medical records of elderly AML patients (n = 187) and compared serum SDF-1α levels with age-matched controls (n = 120). Patients received CAG (cytarabine, aclarubicin, and G-CSF)-based chemotherapy, and serum SDF-1α levels were assessed using ELISA.

Results

Serum SDF-1α levels were significantly elevated in elderly AML patients compared to controls (p < 0.001). Receiver operating characteristic (ROC) analysis confirmed its diagnostic relevance, revealing the area under the ROC curve (AUC) of 0.76. Factors such as age, French-American-British (FAB) classification, Eastern Cooperative Oncology Group (ECOG) performance status, primary AML status, white blood cell count, and bone marrow blast cell ratio, were confirmed to be prognostically relevant. Serum SDF-1α levels were elevated in patients who did not achieve complete remission (NCR) compared to those in complete remission (CR). ROC analysis further highlighted the predictive capability of serum SDF-1α for chemotherapy responsiveness. Independent predictors of treatment failure included age, FAB classification, ECOG status, and serum SDF-1α levels. Following chemotherapy, serum SDF-1α levels decreased in patients in CR but remained unchanged in those in NCR. Higher baseline levels of SDF-1α were associated with shorter overall survival.

Conclusions

Elevated serum SDF-1α levels in elderly AML patients are associated with poor chemotherapy response and shorter survival. Baseline serum SDF-1α levels could serve as a prognostic marker for CAG-based treatment outcomes.

CXCR4 as a therapeutic target in acute myeloid leukemia

Extensive research on the CXCL12-CXCR4 axis in acute myeloid leukemia (AML) has resulted in the incorporation of novel anti-leukemia drugs targeting this axis into therapeutic strategies. However, despite this progress, a comprehensive and up-to-date review addressing the role of the CXCL12-CXCR4 axis in AML's oncogenic processes is lacking. In this review, we examine its molecular aspects influencing cancer progression, such as its impact on autonomous proliferation, apoptotic regulation, chemoresistance mechanisms, and interactions with non-leukemic cells such as MSCs and Treg cells. Additionally, we explore clinical implications, including prognosis, correlation with WBC count, blast count in the bone marrow and peripheral blood, as well as its association with FLT3-ITD, NPM1 mutations, and FAB classification. Finally, this paper extensively discusses drugs that specifically target the CXCL12-CXCR4 axis, including plerixafor/AMD3100, ulocuplumab, peptide E5, and motixafortide, shedding light on their potential therapeutic value in the treatment of AML.

Effects of intravenous pulse methylprednisolone in neuromyelitis optica during the acute phase

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an anti-aquaporin 4 (anti-AQP4) autoantibodies-mediated idiopathic inflammatory demyelinating disease of the central nervous system. While intravenous pulse methylprednisolone (IVMP) is the recommended initial treatment option for acute onset NMOSD, its therapeutic mechanism remains unclear. We hypothesized that IVMP would reduce the expression of pro-inflammatory factors and increase the resolution of inflammation in patients with NMOSD.

METHODS

Mendelian randomization (MR) analysis was used to screen meaningful inflammatory and resolution factors for inclusion. Three MR methods with inverse variance weighting (IVW) were primarily used to identify positive results. Interleukin (IL)-10, IL-1β, IL-6, C-X-C motif chemokine ligand 12 (CXCL12), and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were screened from 41 inflammatory factors, and resolvin D1 (RvD1), maresin 1 (MaR1), and lipoxin A4 (LXA4) were screened from 6 resolution markers for inclusion. Subsequently, 12 patients with NMOSD were enrolled and treated with IVMP. Serum levels of the aforementioned inflammatory and resolution markers were measured by enzyme-linked immunosorbent assay before and after IVMP treatment.

RESULTS

High levels of TRAIL, CXCL12, and IL-1β were associated with an increased risk of NMOSD (TRAIL: odds ratio [OR], 1.582; 95% confidence interval [CI], 1.003-2.495; CXCL12: OR, 3.610; 95% CI, 1.011-12.889; IL-1β: OR, 4.500; 95% CI, 1.129-17.927). High levels of RvD1, MaR1, and LXA4 were associated with a reduced risk of NMOSD (RvD1: OR, 0.725; 95% CI, 0.538-0.976; MaR1: OR, 0.985; 95% CI, 0.970-0.999; LXA4: OR, 0.849; 95% CI, 0.727-0.993). Among patients with NMOSD, serum levels of IL-6, CXCL12, and TRAIL significantly decreased following IVMP treatment, compared with pretreatment levels, while levels of IL-1β, LXA4, and MaR1 significantly increased after IVMP treatment (p < 0.05). A significant positive correlation was observed between CXCL12 levels and Expanded Disability Status Scale (EDSS) scores (r = 0.451, p < 0.05).

CONCLUSION

Several systemic inflammatory regulators associated with the pathogenesis of NMOSD were identified. The protective roles of LXA4 and MaR1 may be indispensable components of glucocorticoid treatment. Therefore, the use of resolution markers may be a potential strategy for improving central nervous system injury in individuals with NMOSD.

Kinetics of leukemic cells in 3D culture with stromal cells and with arginine deprivation stress

Previously, we established a three-dimensional (3D) bone marrow culture system that maintains normal hematopoiesis, including prolongation of hematopoietic stem cell proliferation and differentiation. To analyze the role of bone marrow stromal cells that compose the microenvironment, the growth of a leukemic cell line (K562) in the 3D condition and with arginine deprivation stress was compared with two-dimensional stromal cell monolayers (2D) and suspension cultures without stromal cells (stroma (-)). Arginine is essential for the proliferation and differentiation of erythrocytes. The proliferation and differentiation of K562 cells cultured in the 3D system were stabilized compared with cells in 2D or stroma (-). Furthermore, the number of K562 cells in the G₀/G₁ phase in 3D was increased significantly compared with cells grown in 2D or stroma (-). Interestingly, the mRNA expression of various hematopoietic growth factors of stromal cells in 3D was not different from 2D, even though supportive activity on K562 cell growth was observed in the arginine deprivation condition. Thus, the hematopoietic microenvironment involves multi-dimensional and complex systems including biochemical and physiochemical factors that regulate quiescence, proliferation, activation, and differentiation of normal hematopoietic cells and cloned leukemic cells. Our 3D culture system may be a valuable new tool for investigating leukemic cell-stromal cell interactions in vitro.

Microvesicles of osteoblasts modulate bone marrow mesenchymal stem cell-induced apoptosis to curcumin in myeloid leukemia cells

Microvesicles (MVs) derived from bone marrow niche components have an important role in genetic reprogramming and subsequent drugs induce apoptosis in leukemic cells. Here, we have found that undertreatment of curcumin or daunorubicin, the cross-talk through MVs of KG-1-bone marrow mesenchymal stem cells (BMSCs), significantly downregulates the expression of the survival gene osteopontin (OPN), CXCL-12, IL-6 (interleukin-6), STAT-3, and VCAM-1 (vascular cell adhesion molecule 1) in treated-KG-1 cells as well as exclusively upregulates CXCL-12 in BMSCs. Drug treated-cell populations' MVs of both single cultured osteoblasts (OBs) and cocultured KG-1 + BMSCs + OBs similarly upregulate survival mediators' OPN, CXCL-12, IL-6, STAT-3, and VCAM-1 in treated-KG-1 cells. Likewise, isolated MVs from KG-1 cells or communication between KG-1, BMSCs, and OBs treated by drugs increase the expression of genes OPN, CXCL-12, IL-6, STAT3, and VCAM-1 by OBs. MVs derived from KG-1 + BMSCs + OBs reduce drug-induced apoptosis in KG-1 cells. This suggests MVs-mediated information transfer is a procedure whereby OBs could overcome BMSCs-induced apoptosis in drug-treated-KG-1 cells.

Chemosensitivity is differentially regulated by the SDF-1/CXCR4 and SDF-1/CXCR7 axes in acute lymphoblastic leukemia with MLL gene rearrangements

Although recent advances in chemotherapy have markedly improved outcome of acute lymphoblastic leukemia (ALL), infantile ALL with MLL gene rearrangements (MLL+ALL) is refractory to chemotherapy. We have shown that specific cytokines FLT3 ligand and TGFβ1 both of which are produced from bone marrow stromal cells synergistically induced MLL+ALL cells into chemo-resistant quiescence, and that treatment of MLL+ALL cells with inhibitors against FLT3 and/or TGFβ1 receptor partially but significantly converts them toward chemo-sensitive. In the present study, we showed that MLL+ALL cells expressed CXCR4 and CXCR7, both receptors for the same chemokine stromal cell derived factor-1 (SDF-1), but their biological events were differentially regulated by the SDF-1/CXCR4 and SDF-1/CXCR7 axes and particularly exerted an opposite effect for determining chemo-sensitivity of MLL+ALL cells; enhancement via the SDF-1/CXCR4 axis vs. suppression via the SDF-1/CXCR7 axis. Because cytosine-arabinoside-induced apoptosis of MLL+ALL cells was inhibited by pretreatment with the CXCR4 inhibitor but rather accelerated by pretreatment with the CXCR7 inhibitor, an application of the CXCR7 inhibitor may become a good treatment option in future for MLL+ALL patients. MLL+ALL has a unique gene profile distinguishable from other types of ALL and AML, and should be investigated separately in responses to biological active agents including chemokine inhibitors.

Adipogenic Mesenchymal Stromal Cells from Bone Marrow and Their Hematopoietic Supportive Role: Towards Understanding the Permissive Marrow Microenvironment in Acute Myeloid Leukemia

PURPOSE

The role of bone marrow-derived mesenchymal stem/stromal cells (MSCs) in creating a permissive microenvironment that supports the emergence and progression of acute myeloid leukemia (AML) is not well established. We investigated the extent to which adipogenic differentiation in normal MSCs alters hematopoietic supportive capacity and we undertook an in-depth comparative study of human bone marrow MSCs derived from newly diagnosed AML patients and healthy donors, including an assessment of adipogenic differentiation capacity.

FINDINGS

MSCs from healthy controls with partial induction of adipogenic differentiation, in comparison to MSCs undergoing partial osteogenic differentiation, expressed increased levels of hematopoietic factors and induced greater proliferation, decreased quiescence and reduced in vitro hematopoietic colony forming capacity of CD34(+) hematopoietic stem and progenitor cells (HSPCs). Moreover, we observed that AML-derived MSCs had markedly increased adipogenic potential and delayed osteogenic differentiation, while maintaining normal morphology and viability. AML-derived MSCs, however, possessed reduced proliferative capacity and decreased frequency of subendothelial quiescent MSCs compared to controls.

CONCLUSION

Our results support the notion of a bone marrow microenvironment characterized by increased propensity toward adipogenesis in AML, which may negatively impact normal hematopoiesis. Larger confirmatory studies are needed to understand the impact of various clinical factors. Novel leukemia treatments aimed at normalizing bone marrow niches may enhance the competitive advantage of normal hematopoietic progenitors over leukemia cells.

Functional expression of Tim-3 on blasts and clinical impact of its ligand galectin-9 in myelodysplastic syndromes

T-cell immunoglobulin mucin-3 (Tim-3), an inhibitory immune checkpoint receptor, is highly expressed on acute myeloid leukemia cells and its ligand galectin-9 is reported to drive leukemic progression by binding with Tim-3. However, it remains unclear whether the Tim-3–galectin-9 pathway is associated with the pathophysiology of myelodysplastic syndromes (MDS). Thus, we investigated the expression and function of Tim-3 and the clinical impact of its ligand galectin-9 in MDS. Tim-3 expression levels on MDS blasts by CD45/side-scatter or CD34/CD45 gating were increased as MDS progressed to the advanced stage. Tim-3 expression in the MDS blasts was upregulated in the presence of the cell culture supernatant of human stromal cells or the MDS-related cytokine transforming growth factor-β1. The proliferation of Tim-3⁺ MDS blasts was inhibited by the blockade of anti-Tim-3 antibody. Furthermore, plasma levels of galectin-9 were elevated as MDS progressed to the advanced stage in 70 MDS/acute leukemia transformed from MDS patients and was a prognostic factor in 40 MDS patients. Our data demonstrated that the Tim-3-galectin-9 pathway is associated with the pathogenesis and disease progression of MDS. These findings provide new insight into potential immunotherapy targeting the galectin-9–Tim-3 pathway in MDS.

Mesenchymal Stem and Progenitor Cells in Normal and Dysplastic Hematopoiesis-Masters of Survival and Clonality?

Myelodysplastic syndromes (MDS) are malignant hematopoietic stem cell disorders that have the capacity to progress to acute myeloid leukemia (AML). Accumulating evidence suggests that the altered bone marrow (BM) microenvironment in general, and in particular the components of the stem cell niche, including mesenchymal stem cells (MSCs) and their progeny, play a pivotal role in the evolution and propagation of MDS. We here present an overview of the role of MSCs in the pathogenesis of MDS, with emphasis on cellular interactions in the BM microenvironment and related stem cell niche concepts. MSCs have potent immunomodulatory capacities and communicate with diverse immune cells, but also interact with various other cellular components of the microenvironment as well as with normal and leukemic stem and progenitor cells. Moreover, compared to normal MSCs, MSCs in MDS and AML often exhibit altered gene expression profiles, an aberrant phenotype, and abnormal functional properties. These alterations supposedly contribute to the “reprogramming” of the stem cell niche into a disease-permissive microenvironment where an altered immune system, abnormal stem cell niche interactions, and an impaired growth control lead to disease progression. The current article also reviews molecular targets that play a role in such cellular interactions and possibilities to interfere with abnormal stem cell niche interactions by using specific targeted drugs.

The poor recovery of neuromyelitis optica spectrum disorder is associated with a lower level of CXCL12 in the human brain

Neuromyelitis optica spectrum disorders (NMOSDs) are blindness-causing neuritis. In NMOSD patients, NMO-IgG evokes astrocytopathy that in turn causes demyelination. While measurement of NMO-IgG titer will help neurologists make the diagnosis of NMOSDs, it is not sufficient to evaluate the severity of astrocytopathy. In this study, we compared the different levels of an astrocyte biomarker in cerebrospinal fluid of NMOSD patients with good or poor recovery, and then linked their differences to the changes in remyelinating promoter (CXCL12) levels. Our results indicate that NMO-IgG down-regulated CXCL12 and impaired the remyelinating process, this may be a mechanism contributing to the poor recovery of NMOSDs.

Emerging therapeutic targets for the treatment of human acute myeloid leukemia (part 1) - gene transcription, cell cycle regulation, metabolism and intercellular communication

Human acute myeloid leukemia is a heterogeneous disease and the effect of therapeutic targeting of specific molecular mechanisms will probably vary between patient subsets. Cell cycle regulators are among the emerging targets (e.g., aurora and polo-like kinases, cyclin-dependent kinases). Inhibition of communication between acute myeloid leukemia and stromal cells is also considered; among the most promising of these strategies are inhibition of hedgehog-initiated, CXCR4-CXCL12 and Axl-Gas6 signaling. Finally, targeting of energy and protein metabolism is considered, the most promising strategy being inhibition of isocitrate dehydrogenase in patients with IDH mutations. Thus, several strategies are now considered, and a major common challenge for all of them is to clarify how they should be combined with each other or with conventional chemotherapy, and whether their use should be limited to certain subsets of patients.

RepSox slows decay of CD34+ acute myeloid leukemia cells and decreases T cell immunoglobulin mucin-3 expression

Despite initial response to therapy, most acute myeloid leukemia (AML) patients relapse. To eliminate relapse-causing leukemic stem/progenitor cells (LPCs), patient-specific immune therapies may be required. In vitro cellular engineering may require increasing the "stemness" or immunogenicity of tumor cells and activating or restoring cancer-impaired immune-effector and antigen-presenting cells. Leukapheresis samples provide the cells needed to engineer therapies: LPCs to be targeted, normal hematopoietic stem cells to be spared, and cancer-impaired immune cells to be repaired and activated. This study sought to advance development of LPC-targeted therapies by exploring nongenetic ways to slow the decay and to increase the immunogenicity of primary CD34(+) AML cells. CD34(+) AML cells generally displayed more colony-forming and aldehyde dehydrogenase activity than CD34(-) AML cells. Along with exposure to bone marrow stromal cells and low (1%-5%) oxygen, culture with RepSox (a reprogramming tool and inhibitor of transforming growth factor-β receptor 1) consistently slowed decline of CD34(+) AML and myelodysplastic syndrome (MDS) cells. RepSox-treated AML cells displayed higher CD34, CXCL12, and MYC mRNA levels than dimethyl sulfoxide-treated controls. RepSox also accelerated loss of T cell immunoglobulin mucin-3 (Tim-3), an immune checkpoint receptor that impairs antitumor immunity, from the surface of AML and MDS cells. Our results suggest RepSox may reduce Tim-3 expression by inhibiting transforming growth factor-β signaling and slow decay of CD34(+) AML cells by increasing CXCL12 and MYC, two factors that inhibit AML cell differentiation. By prolonging survival of CD34(+) AML cells and reducing Tim-3, RepSox may promote in vitro immune cell activation and advance development of LPC-targeted therapies.

Heparin-binding epidermal growth factor-like growth factor/diphtheria toxin receptor in normal and neoplastic hematopoiesis

Heparin-binding EGF-like growth factor (HB-EGF) belongs to the EGF family of growth factors. It is biologically active either as a molecule anchored to the membrane or as a soluble form released by proteolytic cleavage of the extracellular domain. HB-EGF is involved in relevant physiological and pathological processes spanning from proliferation and apoptosis to morphogenesis. We outline here the main activities of HB-EGF in connection with normal or neoplastic differentiative or proliferative events taking place primitively in the hematopoietic microenvironment.