Seiichi Okamura

Effect of (-)-epigallocatechin gallate on leukemic blast cells from patients with acute myeloblastic leukemia.

Information on the anti-carcinogenic effect of EGCG, the main constituent of the polyphenols present in Japanese green tea leaves, has recently been accumulating. In this report, we evaluate the effect of EGCG on leukemic blast cells from AML patients. The results showed that EGCG inhibited the proliferation of AML cells in all cases examined. Since AML cells might proliferate by autocrine or paracrine growth mechanisms, we also examined the effect of EGCG on the production of GM-CSF from AML cells. Although EGCG did not directly inhibit the production of GM-CSF, it did inhibit the effect of TNF-alpha or TPA, both of which stimulated AML cells to produce GM-CSF. On the other hand, the modulation of receptors for growth factors might play a role in the proliferation or carcinogenesis of AML cells. We also found that EGCG inhibited the modulation of c-kit, a receptor for stem cell factor, on leukemic cells. These findings suggested that EGCG might be available as a new therapeutic tool for AML patients.

Pretreatment EBV-DNA copy number is predictive of response and toxicities to SMILE chemotherapy for extranodal NK/T-cell lymphoma, nasal type

Purpose: Extranodal NK/T-cell lymphoma, nasal type (ENKL) is an Epstein–Barr virus (EBV)–associated lymphoma for which a new chemotherapeutic regimen called SMILE (steroid, methotrexate, ifosfamide, l-asparaginase, and etoposide) recently showed promising results. Experimental Design: The amount of EBV-DNA was prospectively measured in whole-blood and plasma samples by real-time quantitative PCR from 26 patients registered in the SMILE phase II study. Results: Before treatment, the EBV-DNA was detected in 22 samples of whole blood with a median number of 3,691 copies/mL (range: 0–1.14 × 107), but 15 samples of plasma with a median of 867 copies/mL (range: 0–1.27 × 107). Results of these 2 measurements of EBV-DNA well correlated (R2 = 0.994, P < 0.001). The overall response rate to SMILE was significantly higher in patients with less than 105 copies/mL of EBV-DNA in whole blood at enrollment (90% vs. 20%, P = 0.007) and in patients with less than 104 copies/mL of EBV-DNA in plasma (95% vs. 29%, P = 0.002). The incidence of grade 4 toxicity of SMILE other than leukopenia/neutropenia was significantly higher in patients with 105 copies/mL of EBV-DNA or more in whole blood (100% vs. 29%, P = 0.007) than that of others and in patients with 104 copies/mL or more in plasma (86% vs. 26%, P = 0.002). Conclusions: These findings suggest that whole blood is more sensitive for clinical use than plasma. The EBV-DNA amount in whole blood was useful for predicting tumor response, toxicity, and prognosis after SMILE chemotherapy for ENKL. Clin Cancer Res; 18(15); 4183–90. ©2012 AACR.

Effects of granulocyte colony-stimulating factor on the hemostatic system in healthy volunteers

We previously identified a receptor for granulocyte colony-stimulating factor (G-CSFR) on platelet membranes, and reported that G-CSF enhanced ADP-induced platelet aggregation. Here, we investigated the priming effect of G-CSF on the hemostatic system in healthy volunteers given G-CSF. Following the administration of rhG-CSF (10 micrograms/kg for 30 min div) to 10 healthy volunteers, we found a significant elevation in the maximum platelet aggregation rate induced by ADP or collagen, thromboxane B2 level and amount of thrombin-antithrombin III complex. The D-D dimer and plasminogen activator inhibitor-1 showed no significant changes. These observations indicate that G-CSF administration may induce hypercoagulability in susceptible subjects. Therefore, patients or donors at risk of thrombosis or hypercoagulable state should be followed carefully after G-CSF administration.

Rotenone, a mitochondrial NADH dehydrogenase inhibitor, induces cell surface expression of CD 13 and CD38 and apoptosis in HL-60 cells

We previously demonstrated that the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene was overexpressed in human acute myelogenous leukemia (AML) cells. Since this finding suggested that ND2 gene expression was related to myeloid differentiation, we here investigated the effects of rotenone, a specific NADH dehydrogenase inhibitor, on HL-60 cell growth, differentiation and death. Fifty nM rotenone inhibited the growth of HL-60 cells and caused an increase in the cell population in the G(2) +M phase. In the quantitative comparison of myeloid antigen, the expression of CD13 and CD38 were relatively increased in the rotenone-treated cells. These findings suggest that the inhibition of NADH dehydrogenase changes the cell cycle and induces some specific surface antigens of HL-60 cells. On the other hand, the expression of ND2 gene remained unchanged after the rotenone treatment, suggesting the rotenone-mediated mitochondrial inhibition did not affect the mitochondrial gene expression. Five mu M rotenone strongly inhibited the cellular proliferation. Electron microscopy and an electrophoretic analysis of DNA showed that the majority of the HL-60 cells were induced into typical apoptosis within 24-48 hours. On the basis of this and other studies, we believe that mitochondrial function is directly involved in both cellular differentiation and apoptotic cell death.

Generation of human natural killer cells from peripheral blood CD34+ cells mobilized by granulocyte colony-stimulating factor

We studied the generation of human natural killer (NK) cells from CD34+ cells that were isolated from peripheral blood stem cells (PBSC) mobilized by granulocyte colony‐stimulating factor (G‐CSF). The isolated CD34+ cells were cultured in the presence of a combination of interleukin‐1 (IL‐1α), IL‐2, and stem cell factor for 5 weeks without marrow stroma. We found that the CD34+ cells isolated from G‐CSF‐mobilized PBSC (G‐CSF/PBSC) could differentiate into a population of NK cells which were CD56+(bright)/CD3− and showed morphologic characteristics of large granular lymphocytes. Immunophenotypic analysis of the NK cells thus generated showed that a small proportion of them expressed CD2, CD8 and CD16 surface markers and approximately half of them coexpressed CD7. This NK population exhibited cytotoxic activity against a NK‐sensitive cell line, K562. These observations suggest that CD34+ cells from G‐CSF/PBSC contain precursors of NK cells that can differentiate into functional NK cells.

Phase I study of the combination of irinotecan hydrochloride, carboplatin, and dexamethasone for the treatment of relapsed or refractory malignant lymphoma.

A phase I study of irinotecan hydrochloride (CPT-11), carboplatin, and dexamethasone treatment in 7 patients with relapsed lymphoma and 7 patients with refractory lymphoma was conducted to evaluate the maximal tolerated dose. The 6 female and 8 male patients had a median age of 63 years (range, 45-73 years), a median performance status of 0 (range, 0-2), and a median disease stage of IV.This study included patients with diffuse large B-cell lymphoma (n = 5), adult T-cell leukemia/ lymphoma (n = 2), mantle cell lymphoma (n = 2), follicular lymphoma (n = 2), angioimmunoblastic T-cell lymphoma (n = 1), anaplastic large cell lymphoma (n = 1), and Hodgkin’s lymphoma (n = 1). All patients had received anthracycline-containing combination chemotherapy prior to this therapy.The starting dosage of CPT-11 was 15 mg/m2 per day (days 1–3 and 8–10), and dosage-escalation increments of 5 mg/m2 per day were planned, with fixed dosages of carboplatin (250 mg/m2 per day, day 1) and dexamethasone (40 mg/body, days 1–3 and days 8–10). Five patients were enrolled at level 1, 3 at level 2, 4 at level 3, and 2 at level 4. Ten patients (71%) and 11 patients (79%) experienced grade 3 or 4 hematologic toxicities of leukocytopenia and neutropenia, respectively.Three patients (29%) and 9 patients (64%) experienced grade 3 or 4 thrombocytopenia and anemia, respectively.Two patients who received 30 mg/m2 (level 4) of CPT-11 developed sepsis.We concluded that the recommended dose of CPT-11 with carboplatin and dexamethasone is 25 mg/m2. No deaths were related to this chemotherapy, and no patient developed liver dysfunction.The overall response rate was 36%.We conclude that the combination therapy of CPT-11, carboplatin, and dexamethasone is effective as salvage therapy but that the duration of response is too short.