Junichi Tsukada

Macrophage Inflammatory Protein‐1α Induces Hypercalcemia in Adult T‐Cell Leukemia

Hypercalcemia is observed in >80% of ATL. Serum MIP‐1α levels were elevated in all 24 ATL with hypercalcemia but undetectable in all 10 patients with humoral hypercalcemia of malignancy with solid tumors and in 34 of 37 ATL without hypercalcemia. We propose that serum MIP‐1α is a clinical hallmark for hypercalcemia in ATL.

Apoptosis induction through proteasome inhibitory activity of cucurbitacin D in human T-cell leukemia

Human T‐cell leukemia is an aggressive malignancy of T lymphocytes. T‐cell leukemia has a very poor prognosis, even with intensive chemotherapy, indicating the need for development of new drugs to treat the disease. Triterpenoid cucurbitacins have been shown to have antitumor activity, but the mechanism of this activity is not fully understood.

Mismatch of minor histocompatibility antigen contributes to a graft-versus-leukemia effect rather than to acute GVHD, resulting in long-term survival after HLA-identical stem cell transplantation in Japan

We determined the alleles of five polymorphic molecules including HA-1 and four adhesion molecules for 106 patients transplanted with HLA-identical stem cell grafts and investigated the association of mismatches as correlates of relapse and graft-versus-host disease (GVHD). All 106 recipients underwent stem cell transplantation (SCT) after myeloablative conditioning between 1985 and 2002. Risk status of disease at SCT was standard (n=63) and high (n=42). After SCT, 36, 49 and 33 developed acute GVHD, chronic GVHD and relapsed, respectively. Our patients relapsed at rates of 16.7 and 38.6% with one or more and without incompatibilities (P=0.013). The relapse rates of patients with CD62L, CD31 codon 563, CD31 codon 125, HA-1 and CD49b incompatibilities were 5.9, 11.8, 15.4, 16.0 and 33.3%, respectively. The frequency of acute GVHD did not differ regardless of incompatibilities. In standard-risk group, the accumulated relapse rates of 19 and 44 patients with and without minor histocompatibility antigen incompatibility were 22% and unexpectedly 66%, respectively (P=0.02). The probability of 12-year survival was 88% in the former and 66% in the latter patients (P=0.03). Our data suggest that incompatibility of CD62L, CD31 codon 563 and CD31 codon 125 contributes to a graft-versus-leukemia effect rather than to GVHD, resulting in prolonged survival after HLA-identical SCT.

The effect of high doses of recombinant human erythropoietin on megakaryocytopoiesis and platelet production in splenectomized mice

Summary The effects of recombinant human erythropoietin (rHuEpo) on megakaryocytopoiesis and platelet production were investigated in splenectomized, sham‐operated and intact mice. When splenectomized mice were injected with 50 U of rHuEpo daily for 4 d, peripheral platelet counts, megakaryocyte (MK) size and the percentage of mature MK (stage IV MK) increased from 1 to 4 d after the initial rHuEpo injection. The total number of marrow MK colony forming units (CFU‐MK) increased from 2 to 4 d after the initial injection. Furthermore, from days 6 to 8, the total number of marrow MK also increased. In addition, when the dose of rHuEpo was increased to 20 ˜ 200 U per mouse, clear dose responses were detected in platelet counts and MK numbers. When sham‐operated and intact mice were injected with rHuEpo, no significant change in platelet numbers was detected. The number of MK, MK size and the number of CFU‐MK increased only in spleen, not in bone marrow. Our data indicate that Epo has stimulatory effects on platelet production in vivo, if used in sufficient quantities.

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.

Autophagy is associated with cucurbitacin D-induced apoptosis in human T cell leukemia cells

We previously reported that the inflammasome inhibitor cucurbitacin D (CuD) induces apoptosis in human leukemia cell lines. In the present study, we investigated the effects of co-treatment with an additional Bcl-xL inhibitor, Z36. Treatment with Z36 induced cell death in leukemia cell lines, with MT-4 cells exhibiting the lowest sensitivity to Z36. Co-treatment of cells with Z36 and CuD resulted in a greater degree of cell death for Hut78 and Jurkat cells than treatment with CuD alone. In contrast, co-treatment of MT-4 cells with Z36 and CuD had a suppressive effect on cell death. The autophagy inhibitor 3-methyladenine (3-MA) suppressed the growth of leukemia cell lines HuT78, Jurkat, MT-1, and MT-4. CuD-induced cell death was enhanced by 3-MA in Jurkat cells, but inhibited in MT-4 cells. Western blotting results revealed cleavage of poly(ADP ribose) polymerase (PARP), supporting CuD-induced cell death; 3-MA enhanced CuD-Z36-induced PARP cleavage. Taken together, our results indicate that autophagy negatively regulates chemical-induced cell death of leukemia cells, and that controlling autophagy could be beneficial in the development of more effective chemotherapies against leukemia.

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.

Disseminated Mycobacterium abscessus Complex Infection Manifesting as Multiple Areas of Lymphadenitis and Skin Abscess in the Preclinical Stage of Acute Lymphocytic Leukemia.

A 37-year-old woman was admitted to a hospital due to a prolonged fever and a rash on her legs. She had systemic lymphadenitis and a skin abscess on her left leg. Pathological findings of a left leg skin biopsy revealed abscess formation with granulomatous dermatitis, Mycobacterium abscessus complex was cultured from the resected left supraclavicular lymph node, and disseminated M. abscessus complex infection was diagnosed. She was treated with combination treatment with antimicrobials and percutaneous drainage, and her clinical findings improved. Four months later, she developed acute lymphocytic leukemia. Leukemia is a risk factor for disseminated M. abscessus complex infection, even before developing leukemia.

A case of adult T-cell leukemia/lymphoma with rapid progression of pulmonary areas of ground-glass attenuation and multiple nodules

We report a case of adult T-cell leukemia/lymphoma (ATL) with rapidly progressive pulmonary areas of ground-glass attenuation (GGA) and nodules resulting from acute transformation of chronic ATL. A 48-year-old Japanese man was admitted for progressive dyspnea. Chest computed tomography showed rapidly progressive bilateral pulmonary areas of GGA and nodules. Flow cytometry of bronchoalveolar lavage fluid and immunohistochemical examination of lung biopsy specimens revealed invasion of ATL cells. Systemic chemotherapy improved the pulmonary findings. Rapidly expanding areas of GGA and nodules are a rare manifestation of pulmonary invasion of ATL that clinicians should nevertheless keep in mind.

Myoclonia continua in primary CNS natural killer/T-cell lymphoma, nasal type

A 58-year-old right-handed man presented with 3 months gradual worsening of twitching in his left hand. He had no remarkable medical or family history. Examination demonstrated continuous twitching in his left upper limb and dystonic posture of his left hand (videos 1 and 2 at Neurology.org). Superficial, deep, and cortical sensations were not disturbed in his left upper limb.