Biomedical subjects

Takehiro Higashi

Publications and source records attributed to Takehiro Higashi.

7 recordsLinked to original sources

PubMed2006

Growth suppression of human mast cells expressing constitutively active c-kit receptors by JNK inhibitor SP600125.

Activation of c-jun N-terminal kinase (JNK) through c-kit-mediated phosphatidylinositol 3 (PI3) and Src kinase pathways plays an important role in cell proliferation and survival in mast cells. Gain-of-function mutations in c-kit are found in several human neoplasms. Constitutive activation of c-kit has been observed in human mastocytosis and gastrointestinal stromal tumor. In the present study, we demonstrate that an anthrapyrazole SP600125, a reversible ATP-competitive inhibitor of JNK inhibits proliferation of human HMC-1 showed constitutive activation of JNK/c-Jun, and the inhibitory effect of SP600125 on cell proliferation was associated with cell cycle arrest at the G1 phase and apoptosis accompanied by the cleavage of caspase-3 and PARP. Caspase-3 inhibitor Z-DEVD-FMK almost completely inhibited SP600125-induced apoptosis of HMC-1 cells. In contrast, caspase-9 inhibitor Z-LEHD-FMK failed to block SP600125-induced apoptosis. Following Sp600125 treatment, down-regulation of cyclin D3 protein expression, but not p53 was also observed. Thus, JNK/c-Jun is essential for proliferation and survival of HMC-1 cells. The results obtained from the present study suggest the possibility that JNK/c-Jun may be a therapeutic target in diseases associated with mutations in the catalytic domain of c-kit.

Anthracenes↗

PubMed2005

Constitutive tyrosine and serine phosphorylation of STAT4 in T-cells transformed with HTLV-I.

STAT4 is a critical mediator of IL-12-stimulated gene regulation in T-helper type 1 (Th1) cell. IL-12 activates the Janus family tyrosine kinases JAK2 and Tyk2, which in turn phosphorylate STAT4 on tyrosine 693. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is also activated in response to IL-12, followed by phosphorylation of STAT4 on serine 721, which is required for STAT4 full transcriptional activity. In the present study, we demonstrated constitutive activation of STAT4 in HTLV-I-transformed T-cell lines MT-2, MT-4 and HUT102 by immunoprecipitation, Western blotting and electrophoretic mobility shift assay (EMSA). In HTLV-I-transformed T-cell lines, STAT4 was constitutively phosphorylated not only on tyrosine 693 but also on serine 721, and formed a heterodimer with STAT3. Constitutive phosphorylation of its upstream activators, JAK2, Tyk2 and p38 MAPK was also observed in the cells. EMSA and transient transfection studies further showed that the high-affinity sis-inducible element (hSIE) preferentially binds the STAT3/STAT4 heterodimer and is constitutively transactivated in MT-2 cells in the absence of exogenous cytokine stimulation. When STAT4 expression vector was cotransfected along with STAT3 expression vector into MT-2 cells, STAT4 significantly synergized with STAT3 to transactivate hSIE, showing the functional importance of heterodimer formation between STAT4 and STAT3.

Blotting, Western↗

PubMed2005

[Generalized erythema triggered by a rapid decrease of basophils in chronic myeloid leukemia treated with imatinib].

A 57-year-old woman with chronic myeloid leukemia showing severe basophilia (WBC 17.1 X 10(9)/L, basophils 23%) was treated with 400mg imatinib in June 2003. A high basophil count (WBC 10.6 X 10(9)/L, basophils 31%) was still observed after 1 week of therapy. After 9 days of therapy, she developed generalized pruritic skin erythema, chills and high fever. After terminating imatinib treatment, prednisolone therapy was initiated. The rash quickly disappeared. Four days after withdrawal of imatinib, leukocyte count was 13.0 X 10(9)/L with 3% of basophils, suggesting the possibility that rapid decrease in basophils following imatinib therapy may induce severe cutaneous reactions.

Antineoplastic Agents↗

PubMed2005

[Angioimmunoblastic T-cell lymphoma accompanied by pure red cell aplasia].

A 71-year-old woman was admitted in December 2002 because of lymphadenopathy, hepatosplenomegaly and pleural effusion. She had severe anemia with hemoglobin 5.9 g/dl and a reticulocyte count of 1% per hundred. Direct/indirect Coombs tests and anti-double stranded DNA antibody were positive, her serum CH50 level was reduced and an increase in serum LDH isoenzyme 3 was observed. Bone marrow aspiration showed an almost total absence of erythroblasts and no pathological cell proliferation. The diagnosis of angioimmunoblastic T-cell lymphoma (AILT) was made based on the lymph node histological findings. Proliferation of arborizing small vessels with hyperplastic endothelium and infiltration of atypical T-lymphocytes were observed. After combination chemotherapy (THP-COP), remission was achieved in both the pure red cell aplasia (PRCA) and AILT. Remission was also accompanied by normalization of the Coombs tests, suggesting that autoimmune mechanisms in AILT may contribute to the development of PRCA.

Aged↗

PubMed2004

Imatinib mesylate-sensitive blast crisis immediately after discontinuation of imatinib mesylate therapy in chronic myelogenous leukemia: report of two cases.

Although imatinib mesylate has shown encouraging activity in chronic myelogenous leukemia (CML), disease progression during therapy has been observed, manifested by clonal expansion of imatinib mesylate-resistant leukemia cells. On the other hand, myelosuppression related to treatment of imatinib mesylate is often managed with temporary interruption of treatment or dose reduction. We here report two CML patients who had imatinib mesylate-sensitive blast crisis (BC) immediately after discontinuation of imatinib mesylate therapy. The patients discontinued therapy because of neutropenia. Although there was no evidence of blastic phase during therapy, BC occurred 2 weeks after the withdrawal of treatment in both cases. Interestingly, additional chromosomal abnormalities were detected following the withdrawal of imatinib mesylate and disappeared by re-introduction of this agent. The same doses of imatinib mesylate was still effective and remission was sustained with imatinib mesylate alone again. Our report suggests the possibility that withdrawal of imatinib mesylate may lead to proliferation of blast clones even in patients showing good responses to imatinib mesylate without signs of disease progression.

Aged↗

PubMed2004

[Remission induction of refractory diffuse large B-cell lymphoma with allogeneic peripheral blood stem cell transplantation followed by interferon-alpha and donor lymphocyte infusion].

Graft-versus-lymphoma (GVL) effect has been described in patients with malignant lymphoma after allogeneic stem cell transplantation (alloSCT). The effect of interferon-alpha (IFN-alpha) on the GVL effect still remains unclear. Here we report on a 29-year-old woman with refractory diffuse large B-cell lymphoma (DLBL). Her clinical findings included multiple masses in the liver, stomach, bilateral kidneys, thyroid, vertebral bones and a bulky mediastinal mass. Since the patient did not respond to various combination chemotherapies and further developed superior vena cava syndrome, allogeneic peripheral blood stem cell transplantation (PBSCT) from a HLA-identical brother was carried out after a myeloablative TBI/CY-based conditioning regimen. DLIs have been also performed every 4 weeks since day +14. As a result, the lymphoma masses showed a partial response. In order to enhance the GVL effect, IFN-alpha was further given at a maximum of 3 MU four times per week. Although the patient only experienced graft-versus-host disease of the skin (grade II) even after both DLIs and IFN, complete clinical remission was observed. 200 days after transplantation, the patient is still disease-free and in good condition. This report suggests the curative potential of IFN-alpha combined with DLI after allogeneic SCT in refractory DLBL.

Adult↗

PubMed2003

Primary bilateral adrenal intravascular large B-cell lymphoma associated with adrenal failure.

We report a rare case of bilateral primary adrenal non-Hodgkin's lymphoma with adrenal failure. A 66-year-old woman developed symptoms of adrenal failure. The cause of adrenal failure was suspected to be malignant lymphoma based on the high levels of serum soluble interleukin-2 receptor and LDH. Bilateral adrenalectomy was performed and pathological examination showed intravascular large B-cell lymphoma (IVL). Although complete remission was achieved, recurrence occurred three months later with brain metastases. IVL should be suspected in patients with bilateral adrenal tumors who present with rapidly progressive adrenal failure.

Adrenal Gland Neoplasms↗