Publications by authors named "Misa Imai"

CREB3L1, a gene encoding the endoplasmic reticulum stress transducer, is specifically overexpressed in platelet RNA from patients with myeloproliferative neoplasms (MPNs). However, the pathophysiological roles of CREB3L1 overexpression remain unclear. In the present study, we aimed to study CREB3L1 messenger RNA (mRNA) expression in the red blood cells (RBCs) of patients with MPN and its role in erythrocytosis.

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Identification and functional characterization of disease-associated genetic traits are crucial for understanding the pathogenesis of hematologic malignancies. Various in vitro and in vivo models, including cell lines, primary cells, and animal models, have been established to examine these genetic alterations. However, their nonphysiologic conditions, diverse genetic backgrounds, and species-specific differences often limit data interpretation.

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Article Synopsis
  • - The study focuses on how N-glycan activation of the thrombopoietin receptor (MPL) is involved in diseases caused by mutant calreticulin, which leads to persistent receptor activation in cells.
  • - Researchers identified thrombocorticin (ThC), a marine sponge-derived lectin that activates MPL by forming receptor dimers and has calcium-dependent properties, much like the oncogenic activation.
  • - The findings indicate that sugar chain-mediated activation of MPL is different from its usual activation method, showcasing the potential diversity of receptor activation in biological systems.
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Background: Acquired erythrocytosis can be classified into polycythemia vera (PV) and non-neoplastic erythrocytosis (NNE). The vast majority of PV patients harbor JAK2 mutations, but differentiating JAK2 mutation-negative PV from NNE is challenging due to a lack of definitive molecular markers.

Methods: We studied the clinical features of 121 patients with erythrocytosis of which 47 (38.

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Cyclic AMP-response element-binding protein 3-like 1 (CREB3L1) is a gene involved in the unfolded protein response (UPR). Recently, we demonstrated that CREB3L1 is specifically overexpressed in the platelets of patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). In this study, we aimed to show the clinical and biological relevance of CREB3L1 in these hematological diseases.

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Objectives: Zinc (Zn) is a cofactor for more than 200 enzymes within the human body. Zn deficiency can result in cell-mediated immune dysfunction. Furthermore, serum Zn levels have been reported to be associated with nutritional status, but this association has not been clarified in malignant lymphoma.

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Leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) are quiescent, insensitive to BCR-ABL1 tyrosine kinase inhibitors (TKIs) and responsible for CML relapse. Therefore, eradicating quiescent CML LSCs is a major goal in CML therapy. Here, using a G marker (GM), we narrow down CML LSCs as GM- and CD27- double positive cells among the conventional CML LSCs.

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Characterization and isolation of a large population of cells are indispensable procedures in biological sciences. Flow cytometry is one of the standards that offers a method to characterize and isolate cells at high throughput. When performing flow cytometry, cells are molecularly stained with fluorescent labels to adopt biomolecular specificity which is essential for characterizing cells.

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A subset of essential thrombocythemia (ET) cases are negative for disease-defining mutations on JAK2, MPL, and CALR and defined as triple negative (TN). The lack of recurrent mutations in TN-ET patients makes its pathogenesis ambiguous. Here, we screened 483 patients with suspected ET in a single institution, centrally reviewed bone marrow specimens, and identified 23 TN-ET patients.

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Ruxolitinib (RUX), a JAK1/2-inhibitor, is effective for myeloproliferative neoplasm (MPN) with both JAK2V617 F and calreticulin (CALR) mutations. However, many MPN patients develop resistance to RUX. Although mechanisms of RUX-resistance in cells with JAK2V617 F have already been characterized, those in cells with CALR mutations remain to be elucidated.

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Discrimination of Philadelphia-negative myeloproliferative neoplasms (Ph-MPNs) from reactive hypercytosis and myelofibrosis requires a constellation of testing including driver mutation analysis and bone marrow biopsies. We searched for a biomarker that can more easily distinguish Ph-MPNs from reactive hypercytosis and myelofibrosis by using RNA-seq analysis utilizing platelet-rich plasma (PRP)-derived RNAs from patients with essential thrombocythemia (ET) and reactive thrombocytosis, and CREB3L1 was found to have an extremely high impact in discriminating the two disorders. To validate and further explore the result, expression levels of CREB3L1 in PRP were quantified by reverse-transcription quantitative PCR and compared among patients with ET, other Ph-MPNs, chronic myeloid leukemia (CML), and reactive hypercytosis and myelofibrosis.

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Studies have shown that mutant calreticulin (CALR) constitutively activates the thrombopoietin (TPO) receptor MPL and thus plays a causal role in the development of myeloproliferative neoplasms (MPNs). To further elucidate the molecular mechanism by which mutant CALR promotes MPN development, we studied the subcellular localization of mutant CALR and its importance for the oncogenic properties of mutant CALR. Here, mutant CALR accumulated in the Golgi apparatus, and its entrance into the secretion pathway and capacity to interact with N-glycan were required for its oncogenic capacity via the constitutive activation of MPL.

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Objective: Prefibrotic/early primary myelofibrosis (pre-PMF) and essential thrombocythemia (ET) exhibited different features of bone marrow; however, this is not always easy to judge objectively, making pathologists' distinction often suboptimal. In the WHO 2008 criteria, pre-PMF was not defined as a subgroup of PMF; therefore, affected patients were at a higher risk of misdiagnosis with ET. In this study, we examined the prevalence of pre-PMF patients among those previously diagnosed with ET in Japan.

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Glyoxalase 1 (GLO1) is a ubiquitous enzyme involved in the detoxification of methylglyoxal, a cytotoxic byproduct of glycolysis that induces apoptosis. In this study, we found that GLO1 gene expression correlates with neoplasm histologic grade ( , = 0.002) and is elevated in human basal-like breast cancer tissues.

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Studies have previously shown that mutant calreticulin (CALR), found in a subset of patients with myeloproliferative neoplasms (MPNs), interacts with and subsequently promotes the activation of the thrombopoietin receptor (MPL). However, the molecular mechanism behind the activity of mutant CALR remains unknown. Here we show that mutant, but not wild-type, CALR interacts to form a homomultimeric complex.

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Article Synopsis
  • Somatic mutations in the CALR gene are commonly found in patients with certain myeloproliferative neoplasms (MPNs), especially those who are negative for JAK2 and MPL mutations.
  • Recent research indicates that these CALR mutations lead to the activation of the thrombopoietin receptor MPL, contributing to the development of MPNs, though their exact role in blood cell differentiation remains unclear.
  • By creating induced pluripotent stem cells from patients with a CALR mutation, the study revealed that these cells show increased megakaryocyte development, highlighting their potential for future research and therapeutic testing for MPNs linked to CALR mutations.
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Recurrent somatic mutations in calreticulin (CALR) gene that encodes a molecular chaperone residing in the endoplasmic reticulum were identified in 2013 in a subset of patients with myeloproliferative neoplasms (MPNs). All of these mutations found in patients were either small insertion or deletion in a narrow region on exon 9 of CALR gene, and caused +1 frameshift in the reading frame for the translation of the carboxyl-terminus of CALR. Because of this unique feature, the CALR mutation is believed to be a gain-of-function mutation.

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Differentiation therapy with all--retinoic acid (ATRA) improves the treatment outcome of acute promyelocytic leukemia (APL); however, the molecular mechanism by which ATRA induces granulocytic differentiation remains unclear. We previously reported that the inhibition of the NAD-dependent histone deacetylase (HDAC) SIRT2 induces granulocytic differentiation in leukemia cells, suggesting the involvement of protein acetylation in ATRA-induced leukemia cell differentiation. Herein, we show that p300/CREB-binding protein-associated factor (PCAF), a histone acetyltransferase (HAT), is a prerequisite for ATRA-induced granulocytic differentiation in leukemia cells.

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Asbestos is an environmental carcinogen, and asbestos-related diseases represent a global-scale environmental issue. Mesothelioma is an aggressive, malignant tumor that initially progresses along the surfaces of the pleura and peritoneum that is chiefly attributed to asbestos exposure. X-rays are commonly used for tumor screening in populations at risk for developing this cancer.

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Although recent studies of virus-specific T-cell (VST) therapy for viral infections after allogeneic hematopoietic stem cell transplantation have shown promising results, simple and less time-intensive and labor-intensive methods are required to generate VSTs for the wider application of VST therapy. We investigated the efficacy of anti-CD28 and anti-4-1BB antibodies, which can provide T cells with costimulatory signals similar in strength to those of antigen-presenting cells, in generating VSTs. When peripheral blood mononuclear cells were stimulated with viral peptides together with isotype control, anti-CD28, or anti-4-1BB antibodies, anti-4-1BB antibodies yielded the highest numbers of VSTs, which were on an average 7.

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Article Synopsis
  • - The study explores how chimeric antigen receptor (CAR)-transduced T (CAR-T) cells work, particularly focusing on the threshold of target antigen (Ag) density necessary for effective T cell responses and cytokine production against tumors.
  • - Researchers found that for CAR-T cells to be effective in targeting tumor cells, around 200 antigen molecules are needed for cell lysis, while a much higher density (thousands of molecules) is required for cytokine production.
  • - The newly developed CD20CAR-T cells showed promise against difficult-to-treat lymphomas and leukemias, indicating that understanding the Ag density threshold can help maximize treatment effectiveness while minimizing adverse effects.
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The lysyl oxidase gene inhibits Ras signaling in transformed fibroblasts and breast cancer cells. Its activity was mapped to the 162 amino acid propeptide domain (LOX-PP) of the lysyl oxidase precursor protein. LOX-PP inhibited the Her-2/Ras signaling axis in breast cancer cells, and reduced the Her-2-driven breast tumor burden in a xenograft model.

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