Fucosylation inhibitor 6-alkynylfucose enhances the ATRA-induced differentiation effect on acute promyelocytic leukemia cells.

For acute promyelocytic leukemia (APL), differentiation therapy with all-trans retinoic acid (ATRA) is well established. However, the narrow application and tolerance development of ATRA remain to be improved. In this study, we investigated the effects of combinations of glycosylation inhibitors with ATRA to achieve better efficiency than ATRA alone. We found that the combination of fucosylation inhibitor 6-alkynylfucose (6AF) and ATRA had an additional effect on cell differentiation, as revealed by expression changes in two differentiation markers, CD11b and CD11c, and significant morphological changes in NB4 APL and HL-60 acute myeloid leukemia (AML) cells. In AAL lectin blot analyses, ATRA or 6AF alone could decrease fucosylation, while their combination decreased fucosylation more efficiently. To clarify the molecular mechanism for the 6AF effect on ATRA-induced differentiation, we performed microarray analyses using NB4 cells. In a pathway analysis using DAVID software, we found that the C-type lectin receptor (CLR) signaling pathway was enriched with high significance. In real-time PCR analyses using NB4 and HL-60 cells, FcεRIγ, CLEC6A, CLEC7A, CASP1, IL-1ß, and EGR3, as components of the CLR pathway, as well as CD45 and AKT3 were upregulated by 6AF in ATRA-induced differentiation. Taken together, the present findings suggest that the CLR signaling pathway is involved in the 6AF effect on ATRA-induced differentiation.

Progression of hemolysis in a patient with hereditary spherocytosis after the second dose of COVID-19 mRNA vaccine.

Herein, we report the case of a 22-year-old woman with hereditary spherocytosis (HS) whose condition worsened after administration of the coronavirus disease 2019 (COVID-19), mRNA vaccine 'BNT162b2 Pfizer-BioNTech.' The woman had been diagnosed with HS in 2005, and her condition remained stable until February 2021. In March 2021, she received the first dose of the above vaccine and experienced pain at the injection site. After the second dose in April 2021, she developed fever and general malaise. Investigations revealed progression of hemolysis, which improved after a few days. To the best of our knowledge, this is the first report of progression of hemolysis in a patient with HS after administration of the mRNA vaccine COVID-19, BNT162b2 'Pfizer-BioNTech.'

Suspected Immune Thrombocytopenic Purpura Induced by Lenalidomide for the Treatment of Myelodysplastic Syndrome with Deletion of Chromosome 5q: A Case Report.

Lenalidomide (LEN), one of the key drugs in the treatment of myelodysplastic syndromes (MDS) with 5q deletion, as well as multiple myeloma (MM), has various immunomodulatory effects and has been associated with autoimmune diseases, including immune thrombocytopenic purpura (ITP). A 78-year-old man presented with pancytopenia and was diagnosed with MDS with 5q deletion and other chromosomal abnormalities. Two cycles of LEN therapy (one cycle: 10 mg/day for 21 days) resulted in a transient improvement in anemia, followed by MDS progression with severe thrombocytopenia (4 × 109/L) refractory to platelet transfusions. As other non-immune and alloimmune causes of transfusion-refractory thrombocytopenia were excluded, and the level of platelet-associated immunoglobulin G was extremely high compared with the level before treatment with LEN, the diagnosis of ITP was highly suspected. Despite treatment with prednisolone (PSL), eltrombopag, and repeated platelet transfusions, his platelet count did not increase, and he died of a gastrointestinal hemorrhage. Several cases of ITP induced by LEN used to treat MM had been reported, but the platelet count recovered after administration of PSL in these previous cases. However, we should be mindful of using LEN for patients with MDS because its treatment may become extremely difficult if ITP develops.

Spontaneous Regression of Blastic Plasmacytoid Dendritic Cell Neoplasm Following Sepsis by Serratia marcescens: A Case Report and Literature Review.

Spontaneous regression is rare in patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN). An 85-year-old man presented with pancytopenia and skin lesions, and the bone marrow exhibited 79.6% CD4+, CD56+, CD123+, and TCL-1+ abnormal cells, with a normal karyotype; he was thus diagnosed with BPDCN. While being followed without chemotherapy, he was admitted due to sepsis induced by Serratia marcescens, which was successfully treated with antibiotics. Notably, his blood cell counts improved, and the skin lesions disappeared. To our knowledge, this is the first reported case of spontaneous regression of BPDCN with a decrease in tumor cells in the bone marrow following sepsis.

Long-term survival after cord blood transplantation for acute myeloid leukemia complicated with disseminated fusariosis.

Fusariosis is a critical infectious complication that can develop in immunocompromised hosts, mainly under conditions of prolonged neutropenia, and is often disseminated and associated with a high mortality rate. Disseminated fusariosis developing during the course of hematopoietic stem cell transplantation (HSCT) is a critical condition, and there have been few reports of successful treatment of cases complicated with fusariosis before HSCT. Here, we present a case of acute myeloid leukemia (AML) with the development of fungal endophthalmitis during chemotherapy. Vitrectomy was performed and Fusarium solani infection was confirmed by vitreal culture. The infection was also disseminated to the lung, triceps, and spleen. The splenic lesions disappeared with the administration of antifungal agents, and residual lesions in the lung and triceps were surgically resected. After two courses of consolidation chemotherapy, the patient received cord blood transplantation (CBT) twice because of graft failure in the first transplantation. Antifungal agents were administered continuously during chemotherapy and transplantation. Although Fusarium sinusitis developed after neutrophil engraftment, it was well controlled by surgical resection. Thereafter, the patient has been well without recurrence of fusariosis for more than 2 years since transplantation. A combination of continuous administration of antifungal agents and vigorous surgical intervention may be important for management of disseminated fusariosis in the setting of HSCT.

A case of myelodysplastic syndrome with t(10;18)(q26;q21).

An 82-year-old male was admitted. Pancytopenia, a slightly low white blood cell count (3400/µL), and low levels of red blood cells (2.65 × 106/µL), hemoglobin (10.4 g/dL), and platelets (118,000/µL) were observed. Bone marrow aspiration was performed, revealing hypocellular bone marrow and normal blast levels (0.6%) with no dysplasia. G-banding chromosome analysis revealed the karyotype 45,X,-Y[3]/45, idem, t(10;18)(q26;q21)[13]/46,XY[4]. The patient was diagnosed with myelodysplastic syndrome, unclassified (MDS-U). This is the first case report demonstrating a patient with the chromosomal translocation, t(14;18)(q32;q21), which is extremely rare. This chromosomal aberration was critical for the diagnosis of MDS in this patient.

Multicenter phase 1/2 study of forodesine in patients with relapsed peripheral T cell lymphoma.

Peripheral T cell lymphomas are an aggressive group of non-Hodgkin lymphomas with poor outcomes for most subtypes and no accepted standard of care for relapsed patients. This study evaluated the efficacy and safety of forodesine, a novel purine nucleoside phosphorylase inhibitor, in patients with relapsed peripheral T cell lymphomas. Patients with histologically confirmed disease, progression after ≥ 1 prior treatment, and an objective response to last treatment received oral forodesine 300 mg twice-daily. The primary endpoint was objective response rate (ORR). Secondary endpoints included duration of response, progression-free survival (PFS), overall survival (OS), and safety. Forty-eight patients (median age, 69.5 years; median of 2 prior treatments) received forodesine. In phase 1 (n = 3 evaluable), no dose-limiting toxicity was observed during the first 28 days of forodesine treatment. In phase 2 (n = 41 evaluable), the ORR for the primary and final analyses was 22% (90% CI 12-35%) and 25% (90% CI 14-38%), respectively, including four complete responses (10%). Median PFS and OS were 1.9 and 15.6 months, respectively. The most common grade 3/4 adverse events were lymphopenia (96%), leukopenia (42%), and neutropenia (35%). Dose reduction and discontinuation due to adverse events were uncommon. Secondary B cell lymphoma developed in five patients, of whom four were positive for Epstein-Barr virus. In conclusion, forodesine has single-agent activity within the range of approved therapies in relapsed peripheral T cell lymphomas, with a manageable safety profile, and may represent a viable treatment option for this difficult-to-treat population.

Correction to: Multicenter phase 1/2 study of forodesine in patients with relapsed peripheral T cell lymphoma.

The original version of this article contained a mistake in Fig. 4. The horizontal axis should be 36 instead of 60.

Successful Treatment of Aggressive Mature B-cell Lymphoma Mimicking Immune Thrombocytopenic Purpura.

A 55-year-old woman suffered from hemorrhagic tendency. She had severe thrombocytopenia without any hematological or coagulatory abnormalities, and a bone marrow examination revealed an increased number of megakaryocytes without any abnormal cells or blasts. No lymphadenopathy or hepatosplenomegaly was observed on computed tomography. She was initially diagnosed with immune thrombocytopenic purpura (ITP). None of the treatments administered for ITP produced a response. However, abnormal cells were eventually found during the third bone marrow examination. The pathological diagnosis was mature B-cell lymphoma. Rituximab-containing chemotherapy produced a marked increase in the patient's platelet count, and her lymphoma went into complete remission.

Establishment of a Screening System to Identify Novel GATA-2 Transcriptional Regulators.

Hematopoietic stem cells can self-renew and differentiate into all blood cell types. The transcription factor GATA-2 is expressed in hematopoietic stem and progenitor cells and is essential for cell proliferation and differentiation. Heterozygous germline GATA2 mutations induce GATA-2 deficiency syndrome, characterized by monocytopenia, a predisposition to myelodysplasia and acute myeloid leukemia, and a profoundly reduced dendritic cell (DC) population, which is associated with increased susceptibility to viral infections. Because patients with GATA-2 deficiency syndrome could retain a wild-type copy of GATA-2, boosting residual wild-type GATA-2 activity may represent a novel therapeutic strategy for the disease. Here, we sought to establish a screening system to identify GATA-2 activators using human U937 monocytic cells as a potential model of the DC progenitor. Enforced GATA-2 expression in U937 cells induces CD205 expression, a marker of DC differentiation, indicating U937 cells as a surrogate of human primary DC progenitors. Transient luciferase reporter assays in U937 cells reveals a high promoter activity of the -0.5 kb GATA-2 hematopoietic-specific promoter (1S promoter) fused with two tandemly connected GATA-2 +9.9 kb intronic enhancers. We thus established U937-derived cell lines stably expressing tandem +9.9 kb/-0.5 kb 1S-luciferase. Importantly, forced GATA-1 expression, a repressor for GATA-2 expression, in the stable clones caused significant decreases in the luciferase activities. In conclusion, our system represents a potential tool for identifying novel regulators of GATA-2, thereby contributing to the development of novel therapeutic approaches.

Effects of in vivo deletion of GATA2 in bone marrow stromal cells.

The bone marrow (BM) microenvironment comprises multiple stem cell niches derived from BM mesenchymal stem cells (MSCs). Previous in vitro analyses have suggested that transcription factor GATA2 plays an important role in adipocyte differentiation of BM-MSCs and in hematopoietic support, but the role of GATA2 in vivo remains unknown. We evaluated GATA2 effects in BM-MSCs in vivo. Expression profiling analysis of Gata2-knockout Ter119-CD45- mesenchymal stromal cells obtained from compact bone from tamoxifen-treated Gata2 conditional knockout mice (Gata2f/f/ER-Cre mice) revealed upregulation of 110 genes and downregulation of 141 genes by a factor of 2. Moreover, gene ontology analysis revealed significant enrichment of genes involved in cell adhesion and chemotaxis. We did not find any phenotypic changes when Gata2 was deleted with BM-MSC-related gene promoters, such as Nestin, Prx1, and Lepr, except for a significant decrease in the colony number of Gata2f/f/Prx1-Cre mice. There was a significant decrease in the percentage of the common myeloid progenitor fraction when Gata2 was deleted in all BM cells, except hematopoietic cells after normal BM cells were transplanted into irradiated Gata2f/f/ER-Cre mice with Gata2 subsequently knocked out by tamoxifen administration. In conclusion, GATA2 could affect the function of BM-MSCs in vivo, presumably by regulating the expression of extracellular signals.

Dynamics of absorption, metabolism, and excretion of 5-aminolevulinic acid in human intestinal Caco-2 cells.

5-Aminolevulinic acid (ALA) is a precursor for the biosynthesis of porphyrins and heme. Although the oral administration of ALA has been widely applied in clinical settings, the dynamics of its absorption, metabolism, and excretion within enterocytes remain unknown. In this study, after enterocytic differentiation, Caco-2 cells were incubated with 200 µM ALA and/or 100 µM sodium ferrous citrate (SFC) for up to 72 h. Both ALA and the combination of ALA and SFC promoted the synthesis of heme, without affecting the expression of genes involved in intestinal iron transport, such as DMT1 and FPN. The enhanced heme synthesis in Caco-2 cells was more pronounced under the effect of the combination of ALA and SFC than under the effect of ALA alone, as reflected by the induced expression of heme oxygenase 1 (HO-1), as well as a reduced protein level of the transcriptional corepressor Bach1. Chromatin immunoprecipitation analysis confirmed Bach1 chromatin occupancy at the enhancer regions of HO-1, which were significantly decreased by the addition of ALA and SFC. Finally, Transwell culture of Caco-2 cells suggested that the administered ALA to the intestinal lumen was partially transported into vasolateral space. These findings enhance our understanding of the absorption and metabolism of ALA in enterocytes, which could aid in the development of a treatment strategy for various conditions such as anemia.

Impact of TET2 deficiency on iron metabolism in erythroblasts.

Sideroblastic anemia is characterized by the presence of ring sideroblasts (RSs), which are caused by iron accumulation in the mitochondria of erythroblasts and are present in both the acquired and congenital forms of the disease. However, the mechanism leading to RS formation remains elusive. Acquired sideroblastic anemia is usually observed in myelodysplastic syndrome (MDS). Because a subset of MDS harbors a somatic mutation of TET2, it may be involved in iron metabolism and/or heme biosynthesis in erythroblasts. Tet2 knockdown (Tet2trap) induced exhibited mild normocytic anemia and elevated serum ferritin levels in 4-month-old mice. Although typical RSs were not observed, increased mitochondrial ferritin (FTMT) amounts were observed in the erythroblasts of Tet2-knockdown mice. Quantitative real-time polymerase chain reaction demonstrated significant dysregulation of genes involved in iron and heme metabolism, including Hmox1, Fech, Abcb7, and Sf3b1 downregulation. After the identification of a cytosine-guanine island in the promoters of Fech, Abcb7, and Sf3b1, we evaluated DNA methylation status and found significantly higher methylation levels at the CpG sites in the erythroblasts of Tet2-knockdown mice. Furthermore, Tet2 knockdown in erythroblasts resulted in decreased heme concentration and accumulation of FTMT. Therefore, TET2 plays a role in the iron and heme metabolism in erythroblasts.

Forced FOG1 expression in erythroleukemia cells: Induction of erythroid genes and repression of myelo-lymphoid transcription factor PU.1.

The transcription factor GATA-1-interacting protein Friend of GATA-1 (FOG1) is essential for proper transcriptional activation and repression of GATA-1 target genes; yet, the mechanisms by which FOG1 exerts its activating and repressing functions remain unknown. Forced FOG1 expression in human K562 erythroleukemia cells induced the expression of erythroid genes (SLC4A1, globins) but repressed that of GATA-2 and PU.1. A quantitative chromatin immunoprecipitation (ChIP) analysis demonstrated increased GATA-1 chromatin occupancy at both FOG1-activated as well as FOG1-repressed gene loci. However, while TAL1 chromatin occupancy was significantly increased at FOG1-activated gene loci, it was significantly decreased at FOG1-repressed gene loci. When FOG1 was overexpressed in TAL1-knocked down K562 cells, FOG1-mediated activation of HBA, HBG, and SLC4A1 was significantly compromised by TAL1 knockdown, suggesting that FOG1 may require TAL1 to activate GATA-1 target genes. Promoter analysis and quantitative ChIP analysis demonstrated that FOG1-mediated transcriptional repression of PU.1 would be mediated through a GATA-binding element located at its promoter, accompanied by significantly decreased H3 acetylation at lysine 4 and 9 (K4 and K9) as well as H3K4 trimethylation. Our results provide important mechanistic insight into the role of FOG1 in the regulation of GATA-1-regulated genes and suggest that FOG1 has an important role in inducing cells to differentiate toward the erythroid lineage rather than the myelo-lymphoid one by repressing the expression of PU.1.

An Lysophosphatidic Acid Receptors 1 and 3 Axis Governs Cellular Senescence of Mesenchymal Stromal Cells and Promotes Growth and Vascularization of Multiple Myeloma.

Mesenchymal stromal cells (MSCs) are multipotent progenitor cells and there is much interest in how MSCs contribute to the regulation of the tumor microenvironment. Whether MSCs exert a supportive or suppressive effect on tumor progression is still controversial, but is likely dependent on a variety of factors that are tumor-type dependent. Multiple myeloma (MM) is characterized by growth of malignant plasma cells in the bone marrow. It has been shown that the progression of MM is governed by MSCs, which act as a stroma of the myeloma cells. Although stroma is created via mutual communication between myeloma cells and MSCs, the mechanism is poorly understood. Here we explored the role of lysophosphatidic acid (LPA) signaling in cellular events where MSCs were converted into either MM-supportive or MM-suppressive stroma. We found that myeloma cells stimulate MSCs to produce autotaxin, an indispensable enzyme for the biosynthesis of LPA, and LPA receptor 1 (LPA1) and 3 (LPA3) transduce opposite signals to MSCs to determine the fate of MSCs. LPA3-silenced MSCs (siLPA3-MSCs) exhibited cellular senescence-related phenotypes in vitro, and significantly promoted progression of MM and tumor-related angiogenesis in vivo. In contrast, siLPA1-MSCs showed resistance to cellular senescence in vitro, and efficiently delayed progression of MM and tumor-related angiogenesis in vivo. Consistently, anti-MM effects obtained by LPA1-silencing in MSCs were completely reproduced by systemic administration of Ki6425, an LPA1 antagonist. Collectively, our results indicate that LPA signaling determines the fate of MSCs and has potential as a therapeutic target in MM. Stem Cells 2017;35:739-753.