Leuka

The t(6;9)(p22.3;q34.1) translocation/DEK::NUP214 fusion protein defines a distinct subgroup of younger AML patients classified as a separate disease entity by the World Health Organization. DEK is a nuclear factor with multifunctional roles, including gene regulation, while its fusion partner, NUP214, plays a pivotal role in nuclear export by interacting with transport receptors such as XPO1. However, the precise mechanism by which DEK::NUP214 drives leukemia remains unclear. A comprehensive multi-omics comparison of 57 AML primary samples (including whole genome sequencing, targeted sequencing, transcriptomics, and drug screening with >500 compounds) revealed that t(6;9) cases display a selective response to XPO1 inhibitors (Selinexor & Eltanexor) and a distinct transcriptomic signature characterized by the overexpression of FOXC1 and HOX genes that are key leukemia mediators. CUT&RUN experiments demonstrated the direct binding of DEK::NUP214 to the promoters of FOXC1 and HOXA/B clusters. Strikingly, the expression of these genes and the binding of DEK::NUP214 to their regulatory regions were selectively reduced upon XPO1 inhibition in t(6;9) cells. Altogether, these results identified a novel function of DEK::NUP214 as an XPO1-dependent transcriptional activator of key leukemia drivers and provide a rationale to explore the use of XPO1 inhibitors in this patient population.

Introduction:Mature plasmacytoid dendritic cells (pDCs) proliferation associated with myeloid neoplasms (MPDMN) are recognized as a neoplasm related to fully differentiated pDCs. Although it has been reported for many years, the genomic landscape of MPDMN is poorly understood.Methods:We reported two patients who developed acute myeloid leukemia (French-American-British M5 subtype) coexisted with immunophenotypically mature pDCs proliferation, which fit the diagnosis of MPDMN. We sorted pDCs from myeloid blasts by flow cytometry and performed whole-exome sequencing and RNA sequencing of the two cell populations, respectively.Results:The immunophenotypes of pDCs in both patients were positive for CD123bri, HLA-DR, CD4, CD303, CD304, and negative for CD56, CD34, CD117, and TdT. The variant allele frequency of gene mutations in myeloid blasts and pDCs were similar. The expression data showed myeloid blasts clustered tightly with hematopoietic stem cells, and pDCs from patients clustered tightly with granulocyte-monocyte progenitors/common myeloid progenitor, rather than with pDCs from the GEO platform.Conclusion:Our study suggested that pDCs derived from the leukemic clone, evidenced by a shared mutation profile and similar transcriptional signatures between pDCs and concurrent myeloid blasts.

Most of the targeting moieties, such as antibody fragments or growth factor domains, used to construct targeted toxins for anticancer therapy derive from secretory proteins. These normally fold in the oxidative environment of the endoplasmic reticulum, and hence their folding in bacterial cells can be quite inefficient. For instance, only low amounts of properly folded antimetastatic chimera constituted by the amino-terminal fragment of human urokinase (ATF) fused to the plant ribosome-inactivating protein saporin could be recovered. ATF-saporin was instead secreted efficiently when expressed in eukaryotic cells protected from autointoxication with neutralizing anti-saporin antibodies. Pichia pastoris is a microbial eukaryotic host where these domains can fold into a transport-competent conformation and reach the extracellular medium. We show here that despite some host toxicity codon-usage optimization greatly increased the expression levels of active saporin but not those of an active-site mutant SAP-KQ in GS115 (his4) strain. The lack of any toxicity associated with expression of the latter confirmed that toxicity is due to saporin catalytic activity. Nevertheless, GS115 (his4) cells in flask culture secreted 3.5 mg/L of a histidine-tagged ATF-saporin chimera showing an IC(50) of 6 x 10(-11) M against U937 cells, thus demonstrating the suitability of this expression platform for secretion of toxic saporin-based chimeras.

Down syndrome (DS) is associated with an increased risk of developing hematological malignancies, but the basis for this predisposition is so far unknown. Using fluorescence in situ hybridization with a panel of locus-specific probes on normal and leukemic metaphases, we have found long-arm interstitial deletions of one of the chromosome 21s in the leukemic cells from five patients with DS and leukemia. This finding provides strong evidence for a gene or genes present on chromosome 21 having an important function in the development of leukemia in individuals with Down syndrome.

We have tested the effect of stromal cells on the proliferation in long- and short-term cultures of primitive (Thy-1+, CD34+, CD33-, CD38- , HLA-DR , adherent in vitro and quiescent in vivo) progenitors in normal human bone marrow. These primitive cells produce granulocyte-macrophage colony-forming cells (CFU-GM) that are measured in secondary clonogenic assays. Addition of stromal cells to normal adherent haemopoietic progenitor cells reduced CFU-GM production by 80% (P =0.0002) after 1 week of incubation. In long-term culture (LTC), in the presence of stroma. the normal adherent cells did not produce significant numbers of CFU-GM until 3-4 weeks later which suggests that stromal cells reduce the probability of quiescent cell activation. This effect could not be attributed to soluble inhibitory factors and was specific to stroma grown with, rather than without, methylprednisolone. It was blocked by heparanase (H'ase) II treatment of stromal cells, by phosphatidylinositol-specific phospholipase C (PI-PLC) treatment of progenitor cells, by antibody blocking of beta1 integrin molecules or by exposure to glucose/N-acetyl-D-glucosamine/alpha-methyl-D-mannoside, but not by exposure to galactose or fructose. Moreover, these interventions enabled the progenitor cells to respond to stimulatory factors in the culture supernatant. We interpret these results as support for a model involving primitive progenitor cell binding to stroma by PI-CAM/HS, beta1 integrin activation via lectin-like interactions and the transduction of signals which reduce the ability of primitive cells to respond to ambient stimulators. This model provides a mechanism for the maintenance of the quiescent state of stem cells by adhesion to stromal cells.

Cystoid macular oedema in chronic myeloid leukaemia: Treatment with acetazolamide and response to bone marrow transplantation