bims-almceb Biomed News
on Acute Leukemia Metabolism and Cell Biology
Issue of 2021‒02‒28
fifteen papers selected by
Camila Kehl Dias
Federal University of Rio Grande do Sul

  1. Leukemia. 2021 Feb 25.
      The only current curative treatment for chronic lymphocytic leukemia (CLL) is allogenic hematopoietic stem cell transplantation. Chimeric antigen receptor treatment targeting CD19 for CLL achieved some complete responses, suggesting the need for alternative or combinational therapies to achieve a more robust response. In this work, we evaluated CAR-T cells specific for Siglec-6, an antigen expressed in CLL, as a novel CAR-T cell treatment for CLL. We found that detection of SIGLEC6 mRNA and Siglec-6 protein is highly restricted to placenta and immune cells in other tissues and it is not expressed in hematopoietic stem cells. We generated CAR-T cells specific for Siglec-6 based on the sequence of the fully human anti-Siglec-6 antibody (JML1), which was identified in a CLL patient that was cured after allo-hematopoietic stem cell transplantation (alloHSCT), and observed that it specifically targeted CLL cells in vitro and in a xenograft mouse model. Interestingly, a short hinge region increased the activity of CAR-T cells to target cells expressing higher Siglec-6 levels but similarly targeted CLL cells expressing lower Siglec-6 levels in vitro and in vivo. Our results identify a novel CAR-T cell therapy for CLL and establish Siglec-6 as a possible target for immunotherapy.
  2. Mol Cancer Ther. 2021 Feb 25. pii: molcanther.MCT-20-0476-A.2020. [Epub ahead of print]
      Recent studies have described the remarkable clinical outcome of anti-CD19 chimeric antigen receptor (CAR) T cells in treating B-cell malignancies. However, over 50% of patients develop life-threatening toxicities associated with cytokine release syndrome (CRS) which may limit its utilization in low-resource settings. To mitigate the toxicity, we designed a novel humanized anti-CD19 CAR-T cells by humanizing the framework region of scFv derived from a murine FMC63 mAb and combining it with CD8a transmembrane domain, 4-1BB costimulatory domain and CD3ζ signalling domain (h1CAR19-8BBζ). Docking studies followed by molecular dynamics (MD) simulation revealed that the humanized anti-CD19 scFv (h1CAR19) establishes higher binding affinity and has a flexible molecular structure with CD19 antigen compared to murine scFv (mCAR19). Ex vivo studies with CAR-T cells generated from healthy donors and patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL) expressing either h1CAR19 or mCAR19 showed comparable anti-tumor activity and proliferation. More importantly, h1CAR19-8BBζ-T cells produced lower levels of cytokines (IFN-g, TNF-a upon antigen encounter and reduced the induction of IL-6 cytokine from monocytes than mCAR19-8BBζ-T cells. There was a comparable proliferation of h1CAR19-8BBζ-T cells and mCAR19-8BBζ-T cells upon repeated antigen encounter. Finally, h1CAR19-8BBζ-T cells efficiently eliminated NALM6 tumor cells in a preclinical model. In conclusion, the distinct structural modification in CAR design confers the novel humanized anti-CD19 CAR with a favorable balance of efficacy to toxicity providing a rationale to test this construct in a phase I trial.
  3. Sci Rep. 2021 Feb 23. 11(1): 4390
      The prognosis of metastatic melanoma remains poor due to de novo or acquired resistance to immune and targeted therapies. Previous studies have shown that melanoma cells have perturbed metabolism and that cellular metabolic pathways represent potential therapeutic targets. To support the discovery of new drug candidates for melanoma, we examined 180 metabolic modulators, including phytochemicals and anti-diabetic compounds, for their growth-inhibitory activities against melanoma cells, alone and in combination with the BRAF inhibitor vemurafenib. Two positive hits from this screen, 4-methylumbelliferone (4-MU) and ursolic acid (UA), were subjected to validation and further characterization. Metabolic analysis showed that 4-MU affected cellular metabolism through inhibition of glycolysis and enhanced the effect of vemurafenib to reduce the growth of melanoma cells. In contrast, UA reduced mitochondrial respiration, accompanied by an increase in the glycolytic rate. This metabolic switch potentiated the growth-inhibitory effect of the pyruvate dehydrogenase kinase inhibitor dichloroacetate. Both drug combinations led to increased production of reactive oxygen species, suggesting the involvement of oxidative stress in the cellular response. These results support the potential use of metabolic modulators for combination therapies in cancer and may encourage preclinical validation and clinical testing of such treatment strategies in patients with metastatic melanoma.
  4. Pediatr Blood Cancer. 2021 Feb 26. e28922
      We report on the Australian experience of blinatumomab for treatment of 24 children with relapsed/refractory precursor B-cell acute lymphoblastic leukaemia (B-ALL) and high-risk genetics, resulting in a minimal residual disease (MRD) response rate of 58%, 2-year progression-free survival (PFS) of 39% and 2-year overall survival of 63%. In total, 83% (n = 20/24) proceeded to haematopoietic stem cell transplant, directly after blinatumomab (n = 12) or following additional salvage therapy (n = 8). Four patients successfully received CD19-directed chimeric antigen receptor T-cell therapy despite prior blinatumomab exposure. Inferior 2-year PFS was associated with MRD positivity (20%, n = 15) and in KMT2A-rearranged infants (15%, n = 9). Our findings highlight that not all children with relapsed/refractory B-ALL respond to blinatumomab and factors such as blast genotype may affect prognosis.
    Keywords:  acute lymphoblastic leukaemia; blinatumomab; paediatric; refractory; relapse
  5. J Pediatr Hematol Oncol. 2021 Feb 22.
      While advancements in cellular therapy have improved outcomes for patients with refractory leukemia, severe infections may hinder access. Granulocyte transfusions, in combination with anti-microbial therapy, may be a safe option to facilitate candidacy for chimeric antigen receptor T-cell therapy in patients with leukemia and prolonged immune-compromised status.
  6. Blood. 2021 Feb 22. pii: blood.2020007489. [Epub ahead of print]
      Mitochondria of hematopoietic stem cells (HSCs) play crucial roles in regulating cell fate and preserving HSC functionality and survival. However, the mechanism underlying its regulation remains poorly understood. Here, we identify transcription factor TWIST1 as a novel regulator of HSC maintenance through modulating mitochondrial function. We demonstrate that Twist1 deletion results in a significantly decreased lymphoid-biased (Ly-biased) HSC frequency, markedly reduced HSC dormancy and self-renewal capacities, and skewed myeloid differentiation in steady-state hematopoiesis. Twist1-deficient HSCs are more compromised in tolerance of irradiation and 5-fluorouracil-induced stresses, and exhibit typical phenotypes of senescence. Mechanistically, Twist1 deletion induces transactivation of voltage-gated calcium channel (VGCC) Cacna1b which exhausts Ly-biased HSCs, impairs genotoxic hematopoietic recovery, and enhances mitochondrial calcium levels, metabolic activity, and reactive oxygen species production. Suppression of VGCC by a calcium channel blocker largely rescues the phenotypic and functional defects in Twist1-deleted HSCs under both steady-state and stress conditions. Collectively, our data, for the first time, characterize TWIST1 as a critical regulator of HSC function acting through the CACNA1B/Ca2+/mitochondria axis, and highlight the importance of Ca2+ in HSC maintenance. These observations provide new insights into the mechanisms for the control of HSC fate.
  7. Aging Cell. 2021 Feb 24. e13321
      One of the hallmarks of aging is an accumulation of cells with defects in oxidative phosphorylation (OXPHOS) due to mutations of mitochondrial DNA (mtDNA). Rapidly dividing tissues maintained by stem cells, such as the colonic epithelium, are particularly susceptible to accumulation of OXPHOS defects over time; however, the effects on the stem cells are unknown. We have crossed a mouse model in which intestinal stem cells are labelled with EGFP (Lgr5-EGFP-IRES-creERT2) with a model of accelerated mtDNA mutagenesis (PolgAmut/mut ) to investigate the effect of OXPHOS dysfunction on colonic stem cell proliferation. We show that a reduction in complex I protein levels is associated with an increased rate of stem cell cycle re-entry. These changes in stem cell homeostasis could have significant implications for age-associated intestinal pathogenesis.
    Keywords:  aging; colon; complex I; mitochondria; stem cells
  8. Int J Nanomedicine. 2021 ;16 1231-1244
      Background and Aim: Acute myeloid leukemia (AML), initiated and maintained by leukemia stem cells (LSCs), is often relapsed or refractory to therapy. The present study aimed at assessing the effects of nanozyme-like Fe3O4 nanoparticles (IONPs) combined with cytosine arabinoside (Ara-C) on LSCs in vitro and in vivo.Methods: The CD34+CD38-LSCs, isolated from human AML cell line KG1a by a magnetic activated cell sorting method, were treated with Ara-C, IONPs, and Ara-C+ IONPs respectively in vitro. The cellular proliferation, apoptosis, reactive oxygen species (ROS), and the related molecular expression levels in LSCs were analyzed using flow cytometry, RT-qPCR, and Western blot. The nonobese diabetic/severe combined immune deficiency mice were transplanted with LSCs or non-LSCs via tail vein, and then the mice were treated with Ara-C, IONPs and IONPs plus Ara-C, respectively. The therapeutic effects on the AML bearing mice were further evaluated.
    Results: LSCs indicated stronger cellular proliferation, more clone formation, and more robust resistance to Ara-C than non-LSCs. Compared with LSCs treated with Ara-C alone, LSCs treated with IONPs plus Ara-C showed a significant increase in apoptosis and ROS levels that might be regulated by nanozyme-like IONPs via improving the expression of pro-oxidation molecule gp91-phox but decreasing the expression of antioxidation molecule superoxide dismutase 1. The in vivo results suggested that, compared with the AML bearing mice treated with Ara-C alone, the mice treated with IONPs plus Ara-C markedly reduced the abnormal leukocyte numbers in peripheral blood and bone marrow and significantly extended the survival of AML bearing mice.
    Conclusion: IONPs combined with Ara-C showed the effectiveness on reducing AML burden in the mice engrafted with LSCs and extending mouse survival by increasing LSC's ROS level to induce LSC apoptosis. Our findings suggest that targeting LSCs could control the AML relapse by using IONPs plus Ara-C.
    Keywords:  Fe3O4 nanoparticles; acute myeloid leukemia; cytosine arabinoside; leukemia stem cells; reactive oxygen species
  9. Curr Hematol Malig Rep. 2021 Feb 25.
      PURPOSE OF REVIEW: Chimeric antigen receptor T-cell (CAR-T) therapy is a form of adoptive cellular therapy that has revolutionized the treatment landscape in hematologic malignancies, especially B-cell lymphomas. In this review, we will discuss some of the landmark data behind these therapies and then lay out our approach to utilizing this new therapy.RECENT FINDINGS: CD19-directed CAR-Ts are the most common type currently used in treatment of relapsed B-cell lymphoid neoplasms. There are currently three FDA-approved products: axicabtagene ciluecel and tisagenlecleucel for the treatment of relapsed/refractory large B-cell lymphoma and pediatric B-cell acute lymphocytic leukemia (tisagenlecleucel only) and brexucabtagene autoleucel for the treatment of relapsed/refractory mantle cell lymphoma. These therapies are associated with distinctive acute toxicities such as cytokine release syndrome and neurotoxicity and chronic toxicities such as cytopenias and hypogammaglobulinemia. CAR-T therapy provides significant potential in the treatment of relapsed B-cell lymphomas despite current limitations. Several novel CAR cell designs are currently being studied in clinical trials which include tandem CAR-Ts, allogeneic CAR-Ts, and CAR-NK cells.
    Keywords:  B-cell lymphoma; CAR-NK; Chimeric antigen receptor T-cell (CAR-T); Cytokine release syndrome; Novel CAR-T constructs
  10. Front Immunol. 2020 ;11 585214
      Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that accumulate in tumor-bearing hosts to reduce T cells activity and promote tumor immune escape in the tumor microenvironment (TME). The immune system in the TME can be stimulated to elicit an anti-tumor immune response through immunotherapy. The main theory of immunotherapy resides on the plasticity of the immune system and its capacity to be re-educated into a potent anti-tumor response. Thus, MDSCs within the TME became one of the major targets to improve the efficacy of tumor immunotherapy, and therapeutic strategies for tumor MDSCs were developed in the last few years. In the article, we analyzed the function of tumor MDSCs and the regulatory mechanisms of agents targeting MDSCs in tumor immunotherapy, and reviewed their therapeutic effects in MDSCs within the TME. Those data focused on discussing how to promote the differentiation and maturation of MDSCs, reduce the accumulation and expansion of MDSCs, and inhibit the function, migration and recruitment of MDSCs, further preventing the growth, invasion and metastasis of tumor. Those investigations may provide new directions for cancer therapy.
    Keywords:  cancer; inhibitory factors; myeloid-derived suppressor cells; tumor immunotherapy; tumor microenvironment
  11. Sci Transl Med. 2021 Feb 24. pii: eabc4822. [Epub ahead of print]13(582):
      Chemoresistance remains the major challenge for successful treatment of acute myeloid leukemia (AML). Although recent mouse studies suggest that treatment response of genetically and immunophenotypically indistinguishable AML can be influenced by their different cells of origin, corresponding evidence in human disease is still largely lacking. By combining prospective disease modeling using highly purified human hematopoietic stem or progenitor cells with retrospective deconvolution study of leukemia stem cells (LSCs) from primary patient samples, we identified human hematopoietic stem cells (HSCs) and common myeloid progenitors (CMPs) as two distinctive origins of human AML driven by Mixed Lineage Leukemia (MLL) gene fusions (MLL-AML). Despite LSCs from either MLL-rearranged HSCs or MLL-rearranged CMPs having a mature CD34-/lo/CD38+ immunophenotype in both a humanized mouse model and primary patient samples, the resulting AML cells exhibited contrasting responses to chemotherapy. HSC-derived MLL-AML was highly resistant to chemotherapy and expressed elevated amounts of the multispecific anion transporter ABCC3. Inhibition of ABCC3 by shRNA-mediated knockdown or with small-molecule inhibitor fidaxomicin, currently used for diarrhea associated with Clostridium difficile infection, effectively resensitized HSC-derived MLL-AML toward standard chemotherapeutic drugs. This study not only functionally established two distinctive origins of human LSCs for MLL-AML and their role in mediating chemoresistance but also identified a potential therapeutic avenue for stem cell-associated treatment resistance by repurposing a well-tolerated antidiarrhea drug already used in the clinic.
  12. Nat Metab. 2021 Feb;3(2): 182-195
      Head and neck squamous cell carcinoma (SCC) remains among the most aggressive human cancers. Tumour progression and aggressiveness in SCC are largely driven by tumour-propagating cells (TPCs). Aerobic glycolysis, also known as the Warburg effect, is a characteristic of many cancers; however, whether this adaptation is functionally important in SCC, and at which stage, remains poorly understood. Here, we show that the NAD+-dependent histone deacetylase sirtuin 6 is a robust tumour suppressor in SCC, acting as a modulator of glycolysis in these tumours. Remarkably, rather than a late adaptation, we find enhanced glycolysis specifically in TPCs. More importantly, using single-cell RNA sequencing of TPCs, we identify a subset of TPCs with higher glycolysis and enhanced pentose phosphate pathway and glutathione metabolism, characteristics that are strongly associated with a better antioxidant response. Together, our studies uncover enhanced glycolysis as a main driver in SCC, and, more importantly, identify a subset of TPCs as the cell of origin for the Warburg effect, defining metabolism as a key feature of intra-tumour heterogeneity.
  13. Nat Commun. 2021 02 22. 12(1): 1209
      Fructose intake has increased substantially throughout the developed world and is associated with obesity, type 2 diabetes and non-alcoholic fatty liver disease. Currently, our understanding of the metabolic and mechanistic implications for immune cells, such as monocytes and macrophages, exposed to elevated levels of dietary fructose is limited. Here, we show that fructose reprograms cellular metabolic pathways to favour glutaminolysis and oxidative metabolism, which are required to support increased inflammatory cytokine production in both LPS-treated human monocytes and mouse macrophages. A fructose-dependent increase in mTORC1 activity drives translation of pro-inflammatory cytokines in response to LPS. LPS-stimulated monocytes treated with fructose rely heavily on oxidative metabolism and have reduced flexibility in response to both glycolytic and mitochondrial inhibition, suggesting glycolysis and oxidative metabolism are inextricably coupled in these cells. The physiological implications of fructose exposure are demonstrated in a model of LPS-induced systemic inflammation, with mice exposed to fructose having increased levels of circulating IL-1β after LPS challenge. Taken together, our work underpins a pro-inflammatory role for dietary fructose in LPS-stimulated mononuclear phagocytes which occurs at the expense of metabolic flexibility.
  14. Genes Chromosomes Cancer. 2021 Feb 20.
      We investigated MYB rearrangements (MYB-R) and the levels of MYB expression, in 331 pediatric and adult patients with T-cell acute lymphoblastic leukemia (T-ALL). MYB-R were detected in 17 cases and consisted of MYB tandem duplication (tdup) (=14) or TRB@-MYB (=3). As previously reported, TRB@-MYB was found only in children (1.6%) while MYB tdup occurred in both age groups, although it was slightly more frequent in children (5.2% vs 2.8%). Shared features of MYB-R T-ALL were a non-early T-cell precursor (ETP) phenotype, a high incidence of NOTCH1/FBXW7 mutations (81%) and CDKN2AB deletions (70.5%). Moreover, they mainly belonged to HOXA (=8), NKX2-1/2-2/TLX1 (=4), and TLX3 (=3) homeobox-related subgroups. Overall, MYB-R cases had significantly higher levels of MYB expression than MYB wild type (MYB-wt) cases, although high levels of MYB were detected in ~30% of MYB-wt T-ALL. Consistent with the transcriptional regulatory networks, cases with high MYB expression were significantly enriched within the TAL/LMO subgroup (P = 0.017). Interestingly, analysis of paired diagnosis/remission samples demonstrated that a high MYB expression was restricted to the leukemic clone. Our study has indicated that different mechanisms underlie MYB deregulation in 30-40% of T-ALL and highlighted that, MYB has potential as predictive/prognostic marker and/or target for tailored therapy. This article is protected by copyright. All rights reserved.
    Keywords:  MYB expression; MYB tandem duplication; T-ALL; T-cell acute lymphoblastic leukemia; TRB@-MYB