Leukemic stem cells are multipotent, self-renewing, highly proliferative cells that can withstand drug treatments. Although currently available treatments potentially destroy blast cells, they fail ...to eradicate leukemic progenitor cells completely. Aldehyde dehydrogenase and STAT3 are frequently up-regulated in pre-leukemic stem cells as well as in acute myeloid leukemia (AML) expressing the CD34
CD38
phenotype. The Isatin analog, KS99 has shown anticancer activity against multiple myeloma which may, in part, be mediated by inhibition of Bruton's tyrosine kinase activation. Here we demonstrate that KS99 selectively targets leukemic stem cells with high aldehyde dehydrogenase activity and inhibits phosphorylation of STAT3. KS99 targeted cells co-expressing CD34, CD38, CD123, TIM-3, or CD96 immunophenotypes in AML, alone or in combination with the standard therapeutic agent cytarabine. AML with myelodysplastic-related changes was more sensitive than
AML with or without
mutation. KS99 treatment reduced the clonogenicity of primary human AML cells as compared to normal cord blood mononuclear cells. Downregulation of phosphorylated Bruton's tyrosine kinase, STAT3, and aldehyde dehydrogenase was observed, suggesting interaction with KS99 as predicted through docking. KS99 with or without cytarabine showed
preclinical efficacy in human and mouse AML animal models and prolonged survival. KS99 was well tolerated with overall negligible adverse effects. In conclusion, KS99 inhibits aldehyde dehydrogenase and STAT3 activities and causes cell death of leukemic stem cells, but not normal hematopoietic stem and progenitor cells.
Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Novel effective treatment is an urgent unmet need. Immunotherapy targeting T cell exhaustion by blocking inhibitory ...pathways, such as PD-1, is promising in cancer treatment. However, results from clinical studies applying PD-1 blockade to AML patients are largely disappointing. AML is highly heterogeneous. Identification of additional immune regulatory pathways and defining predictive biomarkers for treatment response are crucial to optimize the strategy. CD26 is a marker of T cell activation and involved in multiple immune processes. Here, we performed comprehensive phenotypic and functional analyses on the blood samples collected from AML patients and discovered that CD26
low
PD-1
+
CD8 T cells were associated with AML progression. Specifically, the percentage of this cell fraction was significantly higher in patients with newly diagnosed AML compared to that in patients achieved completed remission or healthy controls. Our subsequent studies on CD26
low
PD-1
+
CD8 T cells from AML patients at initial diagnosis demonstrated that this cell population highly expressed inhibitory receptors and displayed impaired cytokine production, indicating an exhaustion status. Importantly, CD26
low
PD-1
+
CD8 T cells carried features of terminal exhaustion, manifested by higher frequency of T
EMRA
differentiation, increased expression of transcription factors that are observed in terminally exhausted T cells, and high level of intracellular expression of granzyme B and perforin. Our findings suggest a prognostic and predictive value of CD26 in AML, providing pivotal information to optimize the immunotherapy for this devastating cancer.
Successful treatment for acute myeloid leukemia (AML) remains challenging. Inhibiting immune checkpoint to enhance anti-tumor response is an attractive strategy for effective leukemia therapeutics. ...CD73 is a recently recognized immune checkpoint mediator that is highly expressed on tumor cells and stromal cells in tumor microenvironment. The ectonucleotidase activity of CD73 catalyzes AMP to adenosine, which subsequently inhibits anti-tumor immune responses. In this study, we aim to explore the effect of CD73 in AML.
Peripheral blood samples collected from patients with newly diagnosed AML (n = 27) were used in this study. CD73 expression on each immune cell component was examined by flow cytometry. Phenotypic study of CD73-expressing T cells and analysis of the correlation between CD73 and other immune checkpoints were performed using flow cytometry-based assays. Functional status of CD73
vs. CD73
T cells was assessed in an in vitro cytokine release assay upon CD3/CD28 antibody stimulation.
In contrast to the long recognized immune suppressive effect of CD73-adenosine signaling in tumor tissue, we made a striking observation that in AML, CD73 expression on CD8 T cells associates with an increased immune response. CD73
CD8 T cells are more functional, whereas CD73
CD8 T cells exhibit features of exhaustion manifested by high expression of inhibitory receptors such as PD-1 and TIGIT, increased intracellular expression of Eomes, reduced capacity of cytokine production, and high susceptibility to apoptosis.
Our data highlight the potential of CD73 as a double-edged sword in anti-leukemia immunity and argue strongly for the combinational treatment by adding immune checkpoint inhibitors to the CD73-targeting approaches.
Relapse of acute myeloid leukemia (AML) remains a significant concern due to persistent leukemia-initiating stem cells (LICs) that are typically not targeted by most existing therapies. Using a ...murine AML model, human AML cell lines, and patient samples, we show that AML LICs are sensitive to endogenous and exogenous cyclopentenone prostaglandin-J (CyPG), Δ12-PGJ2, and 15d-PGJ2, which are increased upon dietary selenium supplementation via the cyclooxygenase-hematopoietic PGD synthase pathway. CyPGs are endogenous ligands for peroxisome proliferator-activated receptor gamma and GPR44 (CRTH2; PTGDR2). Deletion of GPR44 in a mouse model of AML exacerbated the disease suggesting that GPR44 activation mediates selenium-mediated apoptosis of LICs. Transcriptomic analysis of GPR44−/− LICs indicated that GPR44 activation by CyPGs suppressed KRAS-mediated MAPK and PI3K/AKT/mTOR signaling pathways, to enhance apoptosis. Our studies show the role of GPR44, providing mechanistic underpinnings of the chemopreventive and chemotherapeutic properties of selenium and CyPGs in AML.
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•Exogenous and dietary selenium supplementation-induced endogenous CyPGs target LICs•CyPG-dependent activation of GPR44 leads to apoptosis of LICs, sparing normal HSCs•GPR44 deletion in LICs enhances RTK-activated KRAS-MAPK and -PI3K/AKT/mTORC axes•Loss of GPR44 increases aggressiveness of AML
Qian et al. describe an important mechanism by which dietary selenium enhances H-PGDS expression that favors production of cyclopentenone prostaglandin (CyPG) production. In addition to activating PPARγ, CyPGs activate GPR44 to suppress RTK-activated KRAS-mediated MAPK and PI3K/AKT/mTORC1 pathways, leading to the P53-mediated apoptosis in AML.
Acute myeloid leukemia is a heterogeneous disease with a 5-year survival rate of 28.3%, and current treatment options constrained by dose-limiting toxicities. One of the key signaling pathways known ...to be frequently activated and dysregulated in AML is PI3K/AKT. Its dysregulation is associated with aggressive cell growth and drug resistance. We investigated the activity of Phenybutyl isoselenocyanate (ISC-4) in primary cells obtained from newly diagnosed AML patients, diverse AML cell lines, and normal cord blood cells. ISC-4 significantly inhibited survival and clonogenicity of primary human AML cells without affecting normal cells. We demonstrated that ISC-4-mediated p-Akt inhibition caused apoptosis in primary AML (CD34
) stem cells and enhanced efficacy of cytarabine. ISC-4 impeded leukemia progression with improved overall survival in a syngeneic C1498 mouse model with no obvious toxic effects on normal myelopoiesis. In U937 xenograft model, bone marrow cells exhibited significant reduction in human CD45
cells in ISC-4 (~87%) or AraC (~89%) monotherapy groups compared to control. Notably, combination treatment suppressed the leukemic infiltration significantly higher than the single-drug treatments (~94%). Together, the present findings suggest that ISC-4 might be a promising agent for AML treatment.
The poor prognosis of acute myeloid leukemia (AML) and the highly heterogenous nature of the disease motivates targeted gene therapeutic investigations. Rho-associated protein kinases (ROCKs) are ...crucial for various actin cytoskeletal changes, which have established malignant consequences in various cancers, yet are still not being successfully utilized clinically towards cancer treatment. This work establishes the therapeutic activity of ROCK inhibitor (5
)-2-5-(1H-pyrrolo2,3-
pyridine-3-ylmethylene)-1,3-thiazol-4(5H)-one (DJ4) in both in vitro and in vivo preclinical models of AML to highlight the potential of this class of inhibitors. Herein, DJ4 induced cytotoxic and proapoptotic effects in a dose-dependent manner in human AML cell lines (IC
: 0.05-1.68 μM) and primary patient cells (IC
: 0.264-13.43 μM); however, normal hematopoietic cells were largely spared. ROCK inhibition by DJ4 disrupts the phosphorylation of downstream targets, myosin light chain (MLC2) and myosin-binding subunit of MLC phosphatase (MYPT), yielding a potent yet selective treatment response at micromolar concentrations, from 0.02 to 1 μM. Murine models injected with luciferase-expressing leukemia cell lines subcutaneously or intravenously and treated with DJ4 exhibited an increase in overall survival and reduction in disease progression relative to the vehicle-treated control mice. Overall, DJ4 is a promising candidate to utilize in future investigations to advance the current AML therapy.
•Distinct sphingolipid metabolism of AML with MDS-related changes defines unique sensitivity to nanoliposomal C6-ceramide.•Vinblastine alters sphingolipid metabolism to enhance the sensitivity of AML ...to nanoliposomal C6-ceramide.
Abstract
Defective DNA repair machinery which is a consequence of chromosomal or molecular alterations is associated with variety of diseases including solid tumors. Cytogenetic analysis is an ...important tool in diagnosis and treatment of hematologic malignancies. Our aim is to understand the role of microsatellite instability in initiation and progression of blood cancers. Here we hypothesize that leukemogenic cells may carry defective repair mechanisms that contribute to other genomic instabilities. In order to explore the possible role of microsatellite instability (MSI) in leukemia and lymphoma, eight different DNA repair genes involved in mismatch repair (MMR) and direct reversal of damage (DRD) were analyzed in K562 (CML), Molt-4 (T-ALL) and Daudi (Burkitt’s lymphoma) cell lines. Fragment analysis was carried out using novel primers considering repeat motifs enriched with (A)n, (CA)n and (AT)n for instability. Almost all the cell lines showed moderate to high level of microsatellite instability and exhibited a shift in selected repeat regions indicating possible loss (66.7%) (MSH2, MSH4, MSH6, MLH1, MLH3, PMS1) or gain (25%) (MSH3, MGMT) of nucleotide repeats as compared to normal DNA. The K562, Philadelphia negative CML cell line appeared to be microsatellite stable (MSS) for genes MSH2 and MLH1. Treatment induced microsatellite instability is known in leukemic patient cells as also seen in Molt-4 cells. Our present and previous observations suggest that MSI is a non-random event in leukemia/lymphoma which needs confirmatory future studies in newly diagnosed untreated patient samples. Considering the fact that both MSI and MSS represents two distinct molecular pathways of carcinogenesis, assessment of MSI, if added as distinct diagnostic criteria, can possibly refine early detection and help in identifying novel targets in management of hematologic malignancies.
Citation Format: Priyanjali Bhattacharya, Naveed Anjum Chikan, Arati Sharma, Dhimant Desai, Charyguly Annageldiyev, Pinaki Patel, Trupti N. Patel. Identification of microsatellite instability in hematologic malignant cell lines abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1741.
Interleukin‐4 (IL‐4) is a signature cytokine pivotal in Type 2 helper T cell (Th2) immune response, particularly in allergy and hypersensitivity. Interestingly, IL‐4 increases endogenous levels of ...prostaglandin D2 (PGD2) and its metabolites, Δ12‐prostaglandin J2 (Δ12‐PGJ2) and 15‐deoxy‐Δ12,14‐prostaglandin J2 (15d‐PGJ2), collectively called cyclopentenone PGs (CyPGs). However, the therapeutic role of IL‐4 in hematologic malignancies remains unclear. Here, we employed a murine model of acute myeloid leukemia (AML), where human MLL‐AF9 fusion oncoprotein was expressed in hematopoietic progenitor cells, to test the effect of IL‐4 treatment in vivo. Daily intraperitoneal treatment with IL‐4 at 60 µg/kg/d significantly alleviated the severity of AML, as seen by decreased leukemia‐initiating cells (LICs). The effect of IL‐4 was mediated, in part, by the enhanced expression of hematopoietic‐ PGD2 synthase (H‐PGDS) to effect endogenous production of CyPGs, through autocrine and paracrine signaling mechanisms. Similar results were seen with patient‐derived AML cells cultured ex vivo with IL‐4. Use of GW9662, a peroxisome proliferator‐activated receptor gamma (PPARγ) antagonist, suggested endogenous CyPGs‐PPARγ axis mediated p53‐dependent apoptosis of LICs by IL‐4. Taken together, our results reveal a beneficial role of IL‐4 treatment in AML suggesting a potential therapeutic regimen worthy of clinical trials in patients with AML.
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