Biomedical subjects

Seishi Ogawa

Publications and source records attributed to Seishi Ogawa.

At least 19 recordsLinked to original sources

PubMed2026

Late acquisition of BCR::ABL1 during clonal evolution of SAMD9-associated MDS with phenotypic shift from AML to B-ALL.

We describe a unique case of SAMD9-associated myelodysplastic syndrome (MDS) with monosomy 7 that evolved over 16 years into BCR::ABL1-positive acute myeloid leukemia (AML) and subsequently manifested as B-cell acute lymphoblastic leukemia (B-ALL). Genomic analysis at AML diagnosis revealed a germline SAMD9 mutation together with somatic RUNX1 and PPM1D mutations, supporting stepwise clonal evolution, with BCR::ABL1 emerging as a late leukemogenic event. The dominant leukemic population at AML onset showed myeloid morphology and immunophenotype, whereas a minor CD19+CD10+ population was already detectable. Following venetoclax and azacitidine therapy, the dominant leukemic phenotype shifted to B-ALL while retaining BCR::ABL1 positivity. Detection of the Philadelphia chromosome in mature neutrophils at both AML onset and ALL relapse supported multilineage involvement of a multipotent BCR::ABL1-positive clone. Ponatinib achieved disease control. This case highlights late acquisition of BCR::ABL1 during SAMD9-associated clonal evolution and therapy-driven phenotypic shift within a shared Ph-positive leukemic stem-cell hierarchy.

Humans↗

PubMed2026

Polycomb repressive complex 2 insufficiency underlies myeloid leukemia in Down syndrome.

Children with Down syndrome (DS) have an elevated risk of developing myeloid leukemia (ML; ML in DS [ML-DS]). In addition to mutations in GATA1, which generate the truncated isoform GATA1-short (GATA1s), ML-DS requires additional somatic gene mutations, most frequently in cohesion and Polycomb repressive complex 2 (PRC2) genes. Here, we show that PRC2 insufficiency underlies ML-DS pathogenesis. Transplantation of Gata1s fetal liver cells followed by deletion of the cohesion subunit Stag2 and/or the PRC2 component Ezh2 induced megakaryocyte-biased differentiation and expansion of megakaryocytic progenitors, culminating in lethal myelofibrosis. Mechanistically, loss of Stag2 or Ezh2 reinforced Gata1s-driven reduced chromatin accessibility at erythroid transcription factor target loci in premegakaryocyte/erythroid progenitors (pre-MegEs), thereby promoting megakaryocytic skewing. Ezh2 loss attenuated the Gata1s-mediated global elevation of H3K27 trimethylation in pre-MegEs, resulting in derepression of a broad set of PRC2 target genes and establishing a functionally PRC2-insufficient state. Similarly, Stag2 loss induced a moderate but significant degree of PRC2-insufficient state in Gata1s progenitors. Furthermore, chromosome 21-encoded miR-125b blocked megakaryocytic differentiation of Gata1s progenitors lacking either Stag2 or Ezh2 alone but drove full transformation and expansion of CD150+Sca-1+c-Kit+ leukemic stem cell-like populations only upon concurrent loss of both Stag2 and Ezh2, leading to acute megakaryoblastic leukemia in mice. These findings reveal that cohesin and PRC2 insufficiencies converge on PRC2 dysfunction while exerting distinct epigenetic effects and synergize with trisomy 21 and GATA1s to remodel the epigenetic landscape, driving progression from a preleukemic state to overt leukemia.

Animals↗

PubMed2026

BCL11B enhancer hijacking by t(14;16)(q32;q24) translocation defines a novel high-risk subtype of T-ALL.

The molecular classification of T-cell acute lymphoblastic leukemia (T-ALL) remains incomplete, limiting risk stratification and the development of targeted therapies. Enhancer hijacking is a critical oncogenic mechanism that deregulates proto-oncogenes by repositioning cisregulatory regions via structural variants. Here, we performed an integrated analysis of pediatric and adult T-ALL and mixed-phenotype acute leukemias (MPALs), using whole-genome and whole-transcriptome sequencing. This analysis identified a group of 14 patients with predominantly T-lineage neoplasms driven by a t(14;16)(q32;q24) translocation, harboring universal GATA3 mutations and CDKN2A/B deletions. Mechanistically, this translocation repositions the ThymoD locus downstream of BCL11B, causing monoallelic, ectopic overexpression of FENDRR and mesenchymal transcription factor genes FOXF1 and FOXC2 and activating epithelial-mesenchymal transition transcription signatures. Immunophenotypic and single-cell RNA sequencing analyses revealed marked lineage ambiguity with myeloid and B-cell differentiation potentials specific to this subtype. Furthermore, functional analyses in CD34+ cord blood cells demonstrated that FOXF1 overexpression promotes myeloid differentiation while suppressing T-cell differentiation, serving as a key factor for lineage specification. Clinically, this subtype was detected in 0.15% to 4.0% of T-ALL/MPAL cases depending on the cohort, showing a median age of 15 years and enrichment in adolescents and young adults. Importantly, patients with t(14;16)(q32;q24) have an extremely poor prognosis, showing a trend toward worse outcomes than high-risk groups such as KMT2A-rearranged early T-cell progenitor-like, SPI1-rearranged, and LMO2 γδ-like T-ALLs. The unique molecular landscape and poor prognosis of patients with the t(14;16)(q32;q24) translocation underscore the need for the development of novel subtype-specific therapeutic approaches.

Humans↗

PubMed2025

High-grade gliomas derived from an ovarian mature teratoma: clonal dynamics and genetic insights.

UNLABELLED: High-grade glioma (HGG) arising from a mature ovarian teratoma is extremely rare and its genetic alterations remain largely unknown. We report a case of WHO Grade 4 HGG (HGG-G4) developing 3 years after cystectomy for ovarian mature teratoma, where a WHO Grade 3 HGG (HGG-G3) was identified upon pathological reevaluation. Whole-exome sequencing confirmed the clonal relationship between HGG-G3 and HGG-G4, revealing genome-wide copy-neutral loss of heterozygosity, copy-number alterations, and whole-genome doubling in both HGGs. Genomic and epigenetic analyses have suggested multistep tumorigenesis and clonal alteration during the clinical course, particularly in response to chemotherapy, in HGGs arising from ovarian teratomas. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13691-025-00790-x.

High-grade glioma↗

PubMed2006

AML1/Runx1 rescues Notch1-null mutation-induced deficiency of para-aortic splanchnopleural hematopoiesis.

The Notch1-RBP-Jkappa and the transcription factor Runx1 pathways have been independently shown to be indispensable for the establishment of definitive hematopoiesis. Importantly, expression of Runx1 is down-regulated in the para-aortic splanchnopleural (P-Sp) region of Notch1- and Rbpsuh-null mice. Here we demonstrate that Notch1 up-regulates Runx1 expression and that the defective hematopoietic potential of Notch1-null P-Sp cells is successfully rescued in the OP9 culture system by retroviral transfer of Runx1. We also show that Hes1, a known effector of Notch signaling, potentiates Runx1-mediated transactivation. Together with the recent findings in zebrafish, Runx1 is postulated to be a cardinal down-stream mediator of Notch signaling in hematopoietic development throughout vertebrates. Our findings also suggest that Notch signaling may modulate both expression and transcriptional activity of Runx1.

Animals↗

PubMed2006

Highly efficient ex vivo expansion of human hematopoietic stem cells using Delta1-Fc chimeric protein.

Ex vivo expansion of hematopoietic stem cells (HSCs) has been explored in the fields of stem cell biology, gene therapy, and clinical transplantation. Here, we demonstrate efficient ex vivo expansion of HSCs measured by long-term severe combined immunodeficient (SCID) repopulating cells (SRCs) from human cord blood CD133-sorted cells using a soluble form of Delta1. After a 3-week culture on immobilized Delta1 supplemented with stem cell factor, thrombopoietin, Flt-3 ligand, interleukin (IL)-3, and IL-6/soluble IL-6 receptor chimeric protein (FP6) in a serum- and stromal cell-free condition, we achieved approximately sixfold expansion of SRCs when evaluated by limiting dilution/transplantation assays. The maintenance of full multipotency and self-renewal capacity during culture was confirmed by transplantation to nonobese diabetic/SCID/gammac(null) mice, which showed myeloid, B, T, and natural killer cells as well as CD133(+)CD34(+) cells, and hematopoietic reconstitution in the secondary recipients. Interestingly, the CD133-sorted cells contained approximately 4.5 times more SRCs than the CD34-sorted cells. The present study provides a promising method to expand HSCs and encourages future trials on clinical transplantation.

AC133 Antigen↗

PubMed2006

Antineoplastic effect of a single oral dose of the novel Flt3 inhibitor KRN383 on xenografted human leukemic cells harboring Flt3-activating mutations.

Activating mutations of Fms-like tyrosine kinase 3 (Flt3) are the most common genetic abnormalities found in acute myeloid leukemia (AML) and represent potential therapeutic targets. The novel Flt3 inhibitor KRN383 inhibited the autophosphorylation of Flt3 bearing internal tandem duplications (ITDs) and the Asp835Tyr (D835Y) point mutation with half-maximal inhibitory concentration (IC(50)) values of < or =5.9 and 43 nM, respectively. KRN383 also inhibited the proliferation of the ITD-positive cell lines with IC(50) values of < or =2.9 nM. A single oral administration of 80 mg/kg of KRN383 eradicated ITD-positive xenograft tumors in nude mice and prolonged the survival of SCID mice carrying ITD-positive AML cells. The effectiveness of a single oral dose of KRN383 suggests that it has the potential to be used in a wide variety of clinical regimens, including multicycle and combination therapies.

Administration, Oral↗

PubMed2006

Influence of glutathione S-transferase A1 polymorphism on the pharmacokinetics of busulfan.

BACKGROUND: High-dose oral busulfan is used for myeloablative chemotherapy before hematopoietic stem-cell transplantation. Fatal adverse effects or relapse may occur with excess or insufficient busulfan exposure. Glutathione S-transferase (GST) A1, whose genetic polymorphism in its promoter region has been reported, is responsible for busulfan metabolism. We investigated the polymorphism of GSTA1 on busulfan pharmacokinetics. METHODS: Blood samples (6 or 7 points) were taken from patients receiving high-dose oral busulfan (approximately 1 mg/kg every 6 h) on Doses 1 and 5. Pharmacokinetic parameters were calculated from plasma busulfan concentration. RESULTS: Twelve patients were enrolled in this study. Nine patients were genotyped as wildtype (GSTA1*A/*A), and 3 as heterozygous variants (GSTA1*A/*B). At Dose 5, the heterozygous group had significantly lower elimination constant (0.176+/-0.038 vs. 0.315+/-0.021 h-1; P=0.008) and clearance corrected by bioavailability (0.118+/-0.013 vs. 0.196+/-0.011 l/h/kg; P=0.004), and significantly higher mean plasma busulfan concentration (1344+/-158 vs. 854+/-44 ng/ml; P=0.001) than the wildtype. CONCLUSIONS: This is the first report on the significant influence of GSTA1 polymorphism on busulfan elimination. This may account for the large inter-individual variance in busulfan pharmacokinetics, and with more information confirming our study, busulfan high-dose therapy may be optimized by GSTA1 genotyping in advance.

Administration, Oral↗

PubMed2006

Pharmacokinetics of alemtuzumab after haploidentical HLA-mismatched hematopoietic stem cell transplantation using in vivo alemtuzumab with or without CD52-positive malignancies.

We recently reported that the addition of in vivo alemtuzumab to the conditioning regimen enables 2- or 3-locus-mismatched hematopoietic stem cell transplantation without an excessive risk of graft rejection or graft-versus-host disease. In a later series of patients, however, one patient with refractory chronic lymphocytic leukemia with large residual tumors at transplantation developed graft rejection. While the peak alemtuzumab concentration in the previous patients without graft rejection was higher than 5 micro g/ml, the peak alemtuzumab concentration in this patient was only 1.44 micro g/ml. We considered that alemtuzumab was bound to the large residual tumors, which resulted in a low blood concentration of alemtuzumab. Therefore, it is important to debulk tumors before the conditioning regimen for patients with refractory CD52-positive hematological malignancies, or the dose of alemtuzumab should be adjusted by monitoring the blood concentration, when alemtuzumab is used for in vivo T-cell depletion in 2- or 3-locus-mismatched transplantation.

Alemtuzumab↗

PubMed2006

Genomewide screening of DNA copy number changes in chronic myelogenous leukemia with the use of high-resolution array-based comparative genomic hybridization.

Chronic myelogenous leukemia (CML) evolves from an indolent chronic phase (CP) characterized by the Philadelphia chromosome. Without effective therapy, it progresses to an accelerated phase (AP) and eventually to a fatal blast crisis (BC). To identify the genes involved in stage progression in CML, we performed a genomewide screening of DNA copy number changes in a total of 55 CML patients in different stages with the use of the high-resolution array-based comparative genomic hybridization (array CGH) technique. We constructed Human 1M arrays that contained 3,151 bacterial artificial chromosome (BAC) DNAs, allowing for an average resolution of 1.0 Mb across the entire genome. In addition to common chromosomal abnormalities, array CGH analysis unveiled a number of novel copy number changes. These alterations included losses in 2q26.2-q37.3, 5q23.1-q23.3, 5q31.2-q32, 7p21.3-p11.2, 7q31.1-q31.33, 8pter-p12(p11.2), 9p, and 22q13.1-q13.31 and gains in 3q26.2-q29, 6p22.3, 7p15.2-p14.3, 8p12, 8p21.3, 8p23.2, 8q24.13-q24.21, 9q, 19p13.2-p12, and 22q13.1-q13.32 and occurred at a higher frequency in AP and BC. Minimal copy number changes affecting even a single BAC locus were also identified. Our data suggests that at least a proportion of CML patients carry still-unknown cryptic genomic alterations that could affect a gene or genes of importance in the disease progression of CML. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Adult↗

PubMed2006

CD1d expression level in tumor cells is an important determinant for anti-tumor immunity by natural killer T cells.

Invariant natural killer T (iNKT) cells are thought to regulate anti-tumor immunity. Human iNKT (i.e. Valpha24+ NKT) cells have been reported to recognize CD1d on target cells and show cytotoxicity directly on the target cells in vitro. However, the anti-tumor effect of mouse iNKT (i.e. Valpha14+ NKT) cells has been repeatedly reported to be dependent on the activity of natural killer (NK) cells via interferon-gamma, with no evidence of direct cytotoxicity. In the present study, we report that in vitro cytolysis of EL-4 mouse lymphoblastic lymphoma cells by Valpha24+ NKT cells and in vivo eradication of these cells are both dependent on the level of CD1d expression on the tumor cell surface. These observations possibly suggest that direct cytotoxicity of tumor cells by iNKT cells is common to both humans and mice, and that the high expression level of CD1d may be a predictor whether the tumor is a good target of iNKT cells.

Animals↗

PubMed2005

Crk-associated substrate lymphocyte type is required for lymphocyte trafficking and marginal zone B cell maintenance.

The lymphocyte-specific Cas family protein Cas-L (Crk-associated substrate lymphocyte type) has been implicated to function in lymphocyte movement, mediated mainly by integrin signaling. However, its physiological role is poorly understood. In this study we analyzed the function of Cas-L in lymphocytes using gene-targeted mice. The mutant mice showed a deficit of marginal zone B (MZB) cells and a decrease of cell number in secondary lymphoid organs. An insufficient chemotactic response and perturbed cell adhesion were observed in Cas-L-deficient lymphocytes, suggesting that the aberrant localization was responsible for the deficit of MZB cells. Moreover, we found that lymphocyte trafficking was altered in Cas-L-deficient mice, which gave a potential reason for contraction of secondary lymphoid tissues. Thus, Cas-L affects homeostasis of MZB cells and peripheral lymphoid organs, which is considered to be relevant to impaired lymphocyte migration and adhesion.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Oligomerization of Evi-1 regulated by the PR domain contributes to recruitment of corepressor CtBP.

Evi-1 is a transcription factor that is implicated in leukemic transformation of hematopoietic cells. Two distinct alternative forms, Evi-1a and Evi-1c, are generated from the EVI-1 gene. Whereas Evi-1a is widely recognized as an oncoprotein, a role for Evi-1c, which has an additional PR domain in the amino-terminus of Evi-1a, in leukemogenesis, has not been elucidated thus far. Aberrant oligomerization of transcription factors has recently emerged as a prevalent mechanism for activating their oncogenic potential in hematopoietic malignancies. Here, to study the mechanisms that underlie Evi-1-mediated oncogenesis, we investigated formation of oligomeric complexes by the Evi-1 proteins. We show that Evi-1a forms homo-oligomers, whereas Evi-1c exclusively exists as a monomer in mammalian cells. Remarkably, Evi-1c has lost the ability to interact with CtBP, a transcriptional corepressor that associates with Evi-1a. As a consequence, the ability of Evi-1c to repress transforming growth factor-beta (TGF-beta) signaling is significantly abrogated. These results identify a novel function of a PR domain to regulate oligomerization of transcription factors and suggest that homo-oligomerization may play a critical role in corepressor recruitment by the Evi-1 proteins. In addition, we found that the chimeric oncoprotein acute myelocytic leukemia (AML)1-Evi-1, generated in t(3;21) leukemia, also forms homo-oligomers and hetero-oligomers with Evi-1a, while it did not interact with Evi-1c. Consistent with the results, repression of TGF-beta by AML1-Evi-1 was significantly enhanced by Evi-1a, whereas it was hardly affected by the presence of Evi-1c. These results suggest that oligomerization may contribute to the oncogenic potential of Evi-1-containing proteins.

Alcohol Oxidoreductases↗

PubMed2005

A robust algorithm for copy number detection using high-density oligonucleotide single nucleotide polymorphism genotyping arrays.

We have developed a robust algorithm for copy number analysis of the human genome using high-density oligonucleotide microarrays containing 116,204 single-nucleotide polymorphisms. The advantages of this algorithm include the improvement of signal-to-noise (S/N) ratios and the use of an optimized reference. The raw S/N ratios were improved by accounting for the length and GC content of the PCR products using quadratic regressions. The use of constitutional DNA, when available, gives the lowest SD values (0.16 +/- 0.03) and also enables allele-based copy number detection in cancer genomes, which can unmask otherwise concealed allelic imbalances. In the absence of constitutional DNA, optimized selection of multiple normal references with the highest S/N ratios, in combination with the data regressions, dramatically improves SD values from 0.67 +/- 0.12 to 0.18 +/- 0.03. These improvements allow for highly reliable comparison of data across different experimental conditions, detection of allele-based copy number changes, and more accurate estimations of the range and magnitude of copy number aberrations. This algorithm has been implemented in a software package called Copy Number Analyzer for Affymetrix GeneChip Mapping 100K arrays (CNAG). Overall, these enhancements make CNAG a useful tool for high-resolution detection of copy number alterations which can help in the understanding of the pathogenesis of cancers and other diseases as well as in exploring the complexities of the human genome.

Algorithms↗

PubMed2005

Host-residual invariant NK T cells attenuate graft-versus-host immunity.

Invariant NK T (iNKT) cells have an invariant TCR-alpha chain and are activated in a CD1d-restricted manner. They are thought to regulate immune responses and play important roles in autoimmunity, allergy, infection, and tumor immunity. They also appear to influence immunity after hemopoietic stem cell transplantation. In this study, we examined the role of iNKT cells in graft-vs-host disease (GVHD) and graft rejection in a mouse model of MHC-mismatched bone marrow transplantation, using materials including alpha-galactosylceramide, NKT cells expanded in vitro, and Jalpha18 knockout mice that lack iNKT cells. We found that host-residual iNKT cells constitute effector cells which play a crucial role in reducing the severity of GVHD, and that this reduction is associated with a delayed increase in serum Th2 cytokine levels. Interestingly, we also found that host-residual iNKT cause a delay in engraftment and, under certain conditions, graft rejection. These results indicate that host-residual iNKT cells attenuate graft-vs-host immunity rather than host-vs-graft immunity.

Adoptive Transfer↗

PubMed2005

In vivo alemtuzumab enables haploidentical human leukocyte antigen-mismatched hematopoietic stem-cell transplantation without ex vivo graft manipulation.

BACKGROUND: Alemtuzumab, a humanized monoclonal antibody directed against human CD52, has a strong lympholytic effect. This study evaluates the safety of unmanipulated peripheral blood stem-cell transplantation from two or three loci-mismatched related donors using alemtuzumab in vivo. METHODS: A total body irradiation-based regimen was used in young patients, whereas those 50 years or older received fludarabine-based conditioning. Alemtuzumab was added to these regimens by intravenous infusion at 0.2 mg/kg per day for 6 days (days -8 to -3). RESULTS: We treated 12 patients with a median age of 49.5 years. Eight patients demonstrated active disease, and four patients demonstrated acute leukemia in high-risk remission. All achieved neutrophil engraftment a median of 17.5 days after transplantation with complete donor-type chimerism. The cumulative incidence of grades III to IV acute graft-versus-host disease was only 9%. Infection-related deaths were not observed. CD3+/CD4+ and CD3+/CD8+ T cells were strongly suppressed within 2 months after transplantation, but recovered on day 90. Relapse was observed in five of eight patients who underwent transplantation for active disease, whereas none of the three patients who underwent transplantation in first remission had a relapse. CONCLUSIONS: We conclude that in vivo alemtuzumab enables haploidentical hematopoietic stem-cell transplantation without ex vivo graft manipulation.

Adult↗

PubMed2005

Graft-versus-tumor effect against advanced pancreatic cancer after allogeneic reduced-intensity stem cell transplantation.

BACKGROUND: The prognosis of advanced pancreatic cancer is extremely poor and therefore a novel treatment strategy is desired. The authors thus started a prospective study of allogeneic reduced-intensity hematopoietic stem cell transplantation (RIST) for patients with advanced pancreatic cancer to evaluate the feasibility and efficacy of this approach for such patients. METHODS: Only patients with pathologically proven pancreatic cancer that was locally advanced or metastatic and not amenable to curative resection were included. The conditioning regimen consisted of gemcitabine, fludarabine, and busulfan. RESULTS: In the first stage of this study, the authors treated seven patients. Treatment-related mortality before day 100 was observed in one patient. The median survival after RIST was 229 days. An objective response on computed tomographic scan was observed in two patients and another had a tumor marker response. Marked tumor shrinkage was observed in one of the remaining patients after donor lymphocyte infusion. These antitumor effects appeared after the effect of the conditioning regimen had disappeared. In addition, some of these responses were associated with an increase in the serum anticarcinoembryonic antigen antibody level. CONCLUSIONS: Pancreatic cancer appeared to be sensitive to a graft-versus-tumor effect; therefore, a larger clinical study with a refined strategy is warranted.

Adult↗

PubMed2005

Functional domains of Runx1 are differentially required for CD4 repression, TCRbeta expression, and CD4/8 double-negative to CD4/8 double-positive transition in thymocyte development.

Runx1 (AML1) has multiple functions in thymocyte development, including CD4 repression in immature thymocytes, expression of TCRbeta, and efficient beta-selection. To determine the functional domains of Runx1 important for thymocyte development, we cultured Runx1-deficient murine fetal liver (FL) cells on OP9-Delta-like 1 murine stromal cells, which express Delta-like 1 and support thymocyte development in vitro, and introduced Runx1 or C-terminal-deletion mutants of Runx1 into the FL cells by retrovirus infection. In this system, Runx1-deficient FL cells failed to follow normal thymocyte development, whereas the introduction of Runx1 into the cells was sufficient to produce thymocyte development that was indistinguishable from that in wild-type FL cells. In contrast, Runx1 mutants that lacked the activation domain necessary for initiating gene transcription did not fully restore thymocyte differentiation, in that it neither repressed CD4 expression nor promoted the CD4/8 double-negative to CD4/8 double-positive transition. Although the C-terminal VWRPY motif-deficient mutant of Runx1, which cannot interact with the transcriptional corepressor Transducin-like enhancer of split (TLE), promoted the double-negative to double-positive transition, it did not efficiently repress CD4 expression. These results suggest that the activation domain is essential for Runx1 to establish thymocyte development and that Runx1 has both TLE-dependent and TLE-independent functions in thymocyte development.

Amino Acid Motifs↗