[Show abstract][Hide abstract] ABSTRACT: Tyrosine kinase inhibitor (TKI) treatment has dramatically improved the outcome of chronic myelogenous leukemia in the chronic phase (CML-CP). However, one study has reported a less favorable treatment outcome with TKIs in adolescents and young adults (AYA) when compared with older patients. In the present study, we retrospectively reviewed the response to TKIs in a Japanese population of 133 CML-CP patients divided into an AYA group (n = 19) and an older group (n = 114). At diagnosis, AYA patients presented with higher white blood cell counts and lower percentage of basophils, and with lower Hasford scores, but no difference was observed in EUTOS score. Probability of achieving complete cytogenetic response was not statistically different between the groups. However, the probabilities of achieving major and complete molecular responses were significantly lower in the AYA group compared to the older group (61 vs 87 % and 17 vs. 33 % at 24 months, respectively; P < 0.05). In addition, a 7-year event-free survival was significantly lower in the AYA compared to the older adults (58 vs. 80 %, P < 0.05). These results suggest that AYA Japanese patients with CML-CP tend to have an unfavorable outcome on treatment with TKI.
Preview · Article · Jul 2015 · International journal of hematology
[Show abstract][Hide abstract] ABSTRACT: A 36-year-old man with diffuse large B-cell lymphoma presented with polyneuropathy, and the diagnostic work-up revealed the presence of IgM antibodies against gangliosides with disialosyl residues (GD1b, GD3). He was treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone and received high-dose intravenous immunoglobulin for the treatment of neuropathy. After initiating the treatments, the patient's neurological impairment improved dramatically. He currently remains in complete remission without a flare-up of the polyneuropathy. Based upon our experience and other case reports of lymphoma with immune-mediated neuropathy caused by anti-disialosyl ganglioside IgM antibodies, we conclude that determining the anti-ganglioside antibody profile and beginning early treatment should be considered promptly for patients with malignant lymphoma who develop polyneuropathy.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the efficacy and safety of a combined regimen of bendamustine (B) and rituximab (R) in Japanese patients with relapsed/refractory (r/r) indolent B-cell non-Hodgkin lymphomas (B-NHLs) and mantle cell lymphoma (MCL). Patients aged 20-79 years with pathologically confirmed B-NHLs or MCL, which were r/r after 1-2 R-containing regimens, were included in this study. The BR regimen consisted of B (90 mg/m(2)) for two consecutive days and R (375 mg/m(2)) on day 1, 2, or 3. The course was repeated every 4 weeks for up to four cycles. Fifty-three patients were enrolled in this study and analyzed. The diagnosis included follicular lymphoma (FL) (77 %), mucosa-associated lymphoid tissue lymphoma (13 %) and others (10 %). Forty-seven (90 %) patients completed four cycles of treatment as per schedule. Best overall response rate (ORR) and complete response rate (CRR) was 94 and 71 %, respectively (for FL, ORR 95 % and CRR 80 %). The treatment was well tolerated and the primary toxicity was myelosuppression; the incidence of grade 3/4 leukopenia and neutropenia were 42 and 40 %, respectively. There were no grade 5 toxicities. The BR regimen is safe in Japanese patients with r/r indolent B-NHLs and MCL, and is effective for those with r/r indolent B-NHLs. For the evaluation of late toxicity, especially infection, longer follow-up of this cohort is needed.
No preview · Article · Mar 2015 · International journal of hematology
[Show abstract][Hide abstract] ABSTRACT: Multiple myeloma (MM) is a clonal plasma cell disorder affecting the immune system with various systemic symptoms. MM remains incurable even with high dose chemotherapy using conventional drugs, thus necessitating development of novel therapeutic strategies. Gossypol (Gos) is a natural polyphenolic compound extracted from cotton plants, and has been shown to possess anti-neoplastic activity against various tumors. Recent studies have shown that Gos is an inhibitor for Bcl-2 or Bcl-XL acting as BH3 mimetics that interfere interaction between pro-apoptotic BH3-only proteins and Bcl-2/Bcl-XL. Since most of the patients with MM overexpress Bcl-2 protein, we considered Gos might be a promising therapeutic agent for MM. We herein show that Gos efficiently induced apoptosis and inhibited proliferation of the OPM2 MM cell line, in a dose- and time-dependent manner. Gos induced activation of caspase-3 and cytochrome c release from mitochondria, showing mitochondrial dysfunction pathway is operational during apoptosis. Further investigation revealed that phosphorylation of Bcl-2 at serine-70 was attenuated by Gos treatment, while protein levels were not affected. In addition, Mcl-1 was downregulated by Gos. Interestingly, phosphorylation of JAK2, STAT3, ERK1/2 and p38MAPK was inhibited by Gos-treatment, indicating that Gos globally suppressed interleukin-6 (IL-6) signals. Moreover, JAK2 inhibition mimicked the effect of Gos in OPM2 cells including Bcl-2 dephosphorylation and Mcl-1 downregulation. These results demonstrated that Gos induces apoptosis in MM cells not only through displacing BH3-only proteins from Bcl-2, but also through inhibiting IL-6 signaling, which leads to Bcl-2 dephosphorylation and Mcl-1 downregulation.
Preview · Article · Sep 2014 · International Journal of Oncology
[Show abstract][Hide abstract] ABSTRACT: Familial platelet disorder (FPD) with predisposition to acute myelogenous leukaemia (AML) is characterized by platelet defects with a propensity for the development of haematological malignancies. Its molecular pathogenesis is poorly understood, except for the role of germline RUNX1 mutations. Here we show that CDC25C mutations are frequently found in FPD/AML patients (53%). Mutated CDC25C disrupts the G2/M checkpoint and promotes cell cycle progression even in the presence of DNA damage, suggesting a critical role for CDC25C in malignant transformation in FPD/AML. The predicted hierarchical architecture shows that CDC25C mutations define a founding pre-leukaemic clone, followed by stepwise acquisition of subclonal mutations that contribute to leukaemia progression. In three of seven individuals with CDC25C mutations, GATA2 is the target of subsequent mutation. Thus, CDC25C is a novel gene target identified in haematological malignancies. CDC25C is also useful as a clinical biomarker that predicts progression of FPD/AML in the early stage.
No preview · Article · Aug 2014 · Nature Communications
[Show abstract][Hide abstract] ABSTRACT: DNA methylation is one of the critical epigenetic modifications regulating various cellular processes such as differentiation or proliferation, and its dysregulation leads to disordered stem cell function or cellular transformation. Ten-eleven translocation (TET) family genes, initially found as a chromosomal translocation partner in leukemia, turned out to be a key enzyme for DNA demethylation. They hydroxylate 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC), which is then converted to unmodified cytosine through multiple mechanisms. On the other hand, somatic mutations of TET2 gene were reported in a variety of human hematological malignancies such as leukemia, myelodysplastic syndrome or malignant lymphoma, suggesting a critical role for TET2 in hematopoiesis. Importance of TET-mediated cytosine demethylation pathway is also underscored by a recurrent mutation of isocytrate dehydrogenase (IDH) 1 and IDH2 in hematological malignancies, whose mutation inhibits TET function through a novel oncometabolite, 2-hydroxyglutarate (2-HG). Studies using mouse models revealed that TET2 is critical for the function of hematopoietic stem cells (HSCs), and disruption of TET2 results in the expansion of multipotent as well as myeloid progenitors, leading to the accumulation of premalignant clones. In addition to cytosine demethylation, TET proteins are involved in chromatin modifications and other cellular processes through the interaction with O-linked β-N-acetylglucosamine transferase (OGT). In summary, TET2 is a critical regulator for HSC homeostasis whose functional impairment leads to hematological malignancies. Future studies will uncover the whole picture of epigenetic and signaling networks wired with TET2, which helps developing ways to intervene dysregulated cellular pathways by TET2 mutations.This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: A 62-year-old man with refractory leukemia transformed from myelodysplastic syndrome was placed on hydroxyurea (hydroxycarbamide) at a daily dose of 500 mg. Because of insufficient cytoreductive efficacy, the dose was increased to 1,500 mg five days later. Eight days after the initiation of hydroxyurea, the patient started complaining of chills, fever, and vomiting. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were markedly elevated to 5,098 and 3,880 IU/l from 44 and 59 IU/l in one day, respectively. Tests for hepatitis viruses were all negative. With the discontinuation of hydroxyurea, AST and ALT returned to their former levels within two weeks. A drug-induced lymphocyte stimulation test for hydroxyurea was positive with a stimulating index of 2.0. Hepatic dysfunction has been recognized as one of the side effects of hydroxyurea. However, there have been only a limited number of reports demonstrating drug allergy to have a role in hepatic dysfunction accompanied by fever and gastrointestinal symptoms. The findings of our case strongly suggest that all presentations could be explained by drug allergy. Physicians should be mindful of the potential for acute and severe hepatic dysfunction due to allergic reaction against hydroxyurea.
No preview · Article · Feb 2014 · [Rinshō ketsueki] The Japanese journal of clinical hematology
[Show abstract][Hide abstract] ABSTRACT: Oncogenic transformation requires unlimited self-renewal. Currently it remains unclear whether a normal capacity for self-renewal is required for acquiring an aberrant self-renewal capacity. Our results in a new conditional transgenic mouse showed that a Mixed Lineage Leukemia (MLL) fusion oncogene, MLL-ENL, at an endogenous-like expression level led to leukemic transformation selectively in a restricted subpopulation of hematopoietic stem cells (HSCs) through upregulation of Promyelocytic leukemia zinc finger (Plzf). Interestingly, forced expression of Plzf itself immortalized HSCs and myeloid progenitors in vitro without upregulation of Hoxa9/Meis1, which are well-known targets of MLL fusion proteins, while its mutant lacking the BTB/POZ domain did not. In contrast, depletion of Plzf suppressed the MLL-fusion-induced leukemic transformation of HSCs in vitro and in vivo. Gene expression analyses of human clinical samples showed that a subtype of PLZF-high MLL-rearranged myeloid leukemia cells was closely associated with the gene expression signature of HSCs. These findings suggested that MLL fusion protein enhances the self-renewal potential of normal HSCs to develop leukemia, in part through a Plzf-driven self-renewal program.
[Show abstract][Hide abstract] ABSTRACT: Roundabout (Robo) family proteins are immunoglobulin-type surface receptors critical for cellular migration and pathway finding of neuronal axons. We have previously shown that Robo4 was specifically expressed in hematopoietic stem and progenitor cells and its high expression correlated with long-term repopulating (LTR) capacity. To reveal the physiological role of Robo4 in hematopoiesis, we examined the effects of Robo4 disruption on the function of hematopoietic stem cells (HSCs) and progenitors. In Robo4-deficient mice, basic hematological parameters including complete blood cell count and differentiation profile were not affected. In contrast to the previous report, HSC/hematopoietic progenitor (HPC) frequencies in the bone marrow (BM) were perfectly normal in Robo4(-/-) mice. Moreover, Robo4(-/-) HSCs were equally competitive as wild-type HSCs in transplantation assays and had normal long-term repopulating (LTR) capacity. Of note, the initial engraftment at 4-weeks after transplantation was slightly impaired by Robo4 ablation, suggesting a marginal defect in BM homing of Robo4(-/-) HSCs. In fact, homing efficiencies of HSCs/HPCs to the BM was significantly impaired in Robo4-deficient mice. On the other hand, granulocyte-colony stimulating factor-induced peripheral mobilization of HSCs was also impaired by Robo4 disruption. Lastly, marrow recovery from myelosuppressive stress was equally efficient in WT- and Robo4-mutant mice. These results clearly indicate that Robo4 plays a role in HSC trafficking such as BM homing and peripheral mobilization, but is not essential in the LTR and self-renewal capacity of HSCs.
[Show abstract][Hide abstract] ABSTRACT: Hematopoietic progenitors have been shown to retain plasticity and switch lineages by appropriate stimuli. However, mature blood cells hardly showed such differentiation plasticity. In this paper, we tried to reprogram mature B cells into erythroid lineage by expressing various hematopoietic transcription factors. Among various factors, GATA-1, SCL together with CCAAT/enhancer binding protein (C/EBP) α turned out to be a minimal set of factors that efficiently reprogrammed terminally differentiated mature B cells into erythroid lineage, as evidenced by colony forming assays and erythroid-specific gene expressions. This study sets an avenue to generate autologous erythrocytes from peripheral B cells.
[Show abstract][Hide abstract] ABSTRACT: Somatic mutation of ten-eleven translocation 2 (TET2) gene is frequently found in human myeloid malignancies. Recent reports showed that loss of Tet2 led to pleiotropic hematopoietic abnormalities including increased competitive repopulating capacity of bone marrow (BM) HSCs and myeloid transformation. However, precise impact of Tet2 loss on the function of fetal liver (FL) HSCs has not been examined. Here we show that disruption of Tet2 results in the expansion of Lin(-)Sca-1(+)c-Kit(+) (LSK) cells in FL. Furthermore, Tet2 loss led to enhanced self-renewal and long-term repopulating capacity of FL-HSCs in in vivo serial transplantation assay. Disruption of Tet2 in FL also led to altered differentiation of mature blood cells, expansion of common myeloid progenitors and increased resistance for hematopoietic progenitor cells (HPCs) to differentiation stimuli in vitro. These results demonstrate that Tet2 plays a critical role in homeostasis of HSCs and HPCs not only in the BM, but also in FL.
Full-text · Article · Feb 2012 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: A 61-year-old female was diagnosed with multiple myeloma (MM) in 2001. After treatment with chemotherapy containing alkylating agents and thalidomide, she underwent autologous stem cell transplantation in 2003, with high-dose melphalan as a conditioning regimen. Thalidomide was also given after the transplant from July 2003 to November 2005 for residual disease and she remained in partial remission. In October 2008, she developed pancytopenia. Bone marrow examination confirmed the diagnosis of acute B lymphoblastic leukemia (B-ALL). We performed IgH gene rearrangement studies on genomic DNA which revealed the MM, and ALL seemed to be derived from different clones. The development of MM and ALL in the same patient is a very rare event. Further accumulation of the cases to understand the mechanism underlying this event is warranted.
No preview · Article · Feb 2012 · [Rinshō ketsueki] The Japanese journal of clinical hematology
[Show abstract][Hide abstract] ABSTRACT: Differentiation of hematopoietic cells is a sequential process of cell fate decision originating from hematopoietic stem cells (HSCs), allowing multi- or oligopotent progenitors to commit to certain lineages. HSCs are cells that are able to self-renew and repopulate the marrow for the long term. They first differentiate into multipotent progenitors (MPPs), which give rise to common lymphoid progenitors (CLPs) and common myeloid progenitors (CMPs). CMPs then differentiate into granulocyte monocyte progenitors (GMPs) and megakaryocyte erythroid progenitors (MEPs), which are the precursors of granulocytes/monocytes and erythrocytes/megakaryocytes, respectively. Lineage specification at differentiation branch points is dictated by the activation of lineage-specific transcription factors such as C/EBPα, PU.1, and GATA-1. The role of these transcription factors is generally instructive, and the expression of a single factor can often determine cell fate. Differentiation was long regarded as an irreversible process, and it was believed that somatic cells would not change their fate once they were differentiated. This paradigm was first challenged by the finding that ectopic cytokine signals could change the fate of differentiation, probably through modulating internal transcription networks. Subsequently, we and others showed that virtually all progenitors, including CLPs, CMPs, GMPs, and MEPs, still retain differentiation plasticity, and they can be converted into lineages other than their own by ectopic activation of only a single lineage-specific transcription factor. These findings established a novel paradigm for cellular differentiation and opened up an avenue for artificially manipulating cell fate for clinical use.
No preview · Article · Jun 2011 · The Keio Journal of Medicine
[Show abstract][Hide abstract] ABSTRACT: Various key cell cycle components, especially G0/G1 regulators, have effects not only on cell proliferation but also on cell differentiation. Cdh1, one of the co-activators that maintain anaphase-promoting complex/cyclosome activity, plays a crucial role in the mitotic phase, but has recently been identified as a G0/G1 regulator, suggesting that the role of Cdh1 in cell differentiation. Here, we generated Cdh1 conditional gene-trap mice to examine Cdh1 functions in adult tissues by overcoming the embryonic lethality of Cdh1 homozygous gene-trap mice. We focused on the hematopoietic system and found that Cdh1-deficient mice exhibited a general decrease in mature lineage progenitor cells and a significant increase in short-term hematopoietic stem cells. This phenomenon became conspicuous by irradiation shortly after Cdh1 downregulation, suggesting that Cdh1 regulates the pool sizes of the hematopoietic stem cells and mature lineage progenitor cells by protecting cells from genotoxic stress. We also found that the irradiation-induced G2/M checkpoint was defective in Cdh1-deficient BM cells, causing the loss of stem/progenitor cells. This is the first report revealing Cdh1 function in adult hematopoiesis and showing a role of Cdh1 in a G2/M checkpoint regulation in vivo.
[Show abstract][Hide abstract] ABSTRACT: Regulating transition of hematopoietic stem cells (HSCs) between quiescent and cycling states is critical for maintaining homeostasis of blood cell production. The cycling states of HSCs are regulated by the extracellular factors such as cytokines and extracellular matrix; however, the molecular circuitry for such regulation remains elusive. Here we show that tissue inhibitor of metalloproteinase-3 (TIMP-3), an endogenous regulator of metalloproteinases, stimulates HSC proliferation by recruiting quiescent HSCs into the cell cycle. Myelosuppression induced TIMP-3 in the bone marrow before hematopoietic recovery. Interestingly, TIMP-3 enhanced proliferation of HSCs and promoted expansion of multipotent progenitors, which was achieved by stimulating cell-cycle entry of quiescent HSCs without compensating their long-term repopulating activity. Surprisingly, this effect did not require metalloproteinase inhibitory activity of TIMP-3 and was possibly mediated through a direct inhibition of angiopoietin-1 signaling, a critical mediator for HSC quiescence. Furthermore, bone marrow recovery from myelosuppression was accelerated by over-expression of TIMP-3, and in turn, impaired in TIMP-3-deficient animals. These results suggest that TIMP-3 may act as a molecular cue in response to myelosuppression for recruiting dormant HSCs into active cell cycle and may be clinically useful for facilitating hematopoietic recovery after chemotherapy or ex vivo expansion of HSCs.
[Show abstract][Hide abstract] ABSTRACT: Two types of mutations of a transcription factor CCAAT-enhancer binding protein α (C/EBPα) are found in leukemic cells of 5%-14% of acute myeloid leukemia (AML) patients: N-terminal mutations expressing dominant negative p30 and C-terminal mutations in the basic leucine zipper domain. Our results showed that a mutation of C/EBPα in one allele was observed in AML after myelodysplastic syndrome, while the 2 alleles are mutated in de novo AML. Unlike an N-terminal frame-shift mutant (C/EBPα-N(m))-transduced cells, a C-terminal mutant (C/EBPα-C(m))-transduced cells alone induced AML with leukopenia in mice 4-12 months after bone marrow transplantation. Coexpression of both mutants induced AML with marked leukocytosis with shorter latencies. Interestingly, C/EBPα-C(m) collaborated with an Flt3-activating mutant Flt3-ITD in inducing AML. Moreover, C/EBPα-C(m) strongly blocked myeloid differentiation of 32Dcl3 cells, suggesting its class II mutation-like role in leukemogenesis. Although C/EBPα-C(m) failed to inhibit transcriptional activity of wild-type C/EBPα, it suppressed the synergistic effect between C/EBPα and PU.1. On the other hand, C/EBPα-N(m) inhibited C/EBPα activation in the absence of PU.1, despite low expression levels of p30 protein generated by C/EBPα-N(m). Thus, 2 types of C/EBPα mutations are implicated in leukemo-genesis, involving different and cooperating molecular mechanisms.