Jiroh Nishimaki

Vitamin K2 and its derivatives induce apoptosis in leukemia cells and enhance the effect of all-trans retinoic acid

Geranylgeraniol, a polyprenylalcohol composing the side chain of vitamin K2 (VK2), was previously reported to be a potent inducer of apoptosis in tumor cell lines (Ohzumi H et al, J Biochem 1995; 117: 11–13). We examined the apoptosis-inducing ability of VK2 (menaquinone 3 (MK3), MK4 and MK5) and its derivatives such as phytonadione (VK1), as well as polyprenylalcohols with side chains of various lengths including farnesol (C15-OH; FO), geranylgeraniol (C20-OH; GGO), and geranylfarnesol (C25-OH; GFO) toward leukemia cells in vitro. MK3, MK4, MK5 and GFO (at 10 μM) showed a potent apoptosis-inducing activity for all freshly isolated leukemia cells tested and for leukemia cell lines such as NB4, an acute promyelocytic leukemia (APL)-derived cell line and MDS92, a cell line derived from a patient with myelodysplastic syndrome, although there were some differences depending on the cells tested. In contrast, VK1 showed no effect on any of the leukemia cells. The combination of MK5 plus all-trans retinoic acid (ATRA) resulted in enhanced induction of apoptosis in both freshly isolated APL cells and NB4 cells as compared to each reagent alone. These data suggest the possibility of using VK2 and its derivatives for the treatment of myelogenous leukemias, including APL.

Vitamin K2 selectively induces apoptosis of blastic cells in myelodysplastic syndrome: flow cytometric detection of apoptotic cells using APO2.7 monoclonal antibody

We have previously reported that vitamin K2 (VK2) but not VK1 has a potent apoptosis-inducing effect on freshly isolated leukemia cells from patients with various types of leukemia. By multi-color flow cytometric analysis using monoclonal antibody (mAb), APO2.7, which detects mitochondrial 7A6 antigen specifically expressed by cells undergoing apoptosis, we further investigated the apoptosis-inducing effect of VK2 on minor populations of leukemic blast cells in bone marrow from patients with myelodysplastic syndrome (MDS) and overt myeloid leukemia (post-MDS AML). Limiting dilution of CD95 (anti-Fas) mAb-treated apoptotic Jurkat cells with nonapoptotic CTB-1 cells revealed that APO2.7-positive Jurkat cells were consistently detectable by flow cytometry when present at levels of at least 5% in the CTB-1 suspension. In patient samples the gating area for leukemic clone was determined using cell surface antigen-specific mAbs conjugated with either fluorescein isothionate (FITC) or phycoerythrin (PE) and subsequently the cells stained with phycoerythrin cyanine (PE-Cy5)-conjugated APO2.7 mAb were assessed within the gating area of the leukemic clone for monitoring apoptosis. Treatment of the bone marrow mononuclear cells with 3–10 μM of VK2 (menaquinone-3, -4 and -5) in vitro potently induced apoptosis of the leukemic blast cells as compared with the untreated control cells in all 15 MDS patients tested. This effect was more prominent on blastic cells than that on mature myeloid cells such as CD34−/CD33++ gated cells. In addition, VK2 performed much less effectively on CD3-positive lymphoid cells. In contrast to VK2, VK1 did not show apoptosis-inducing activity. These data suggest that VK2 may be used for treatment of patients with MDS in blastic transformation.

Vitamin K2 therapy for myelodysplastic syndromes (MDS) and post-MDS acute myeloid leukemia: information through a questionnaire survey of multi-center pilot studies in Japan

Vitamin K 2 therapy for myelodysplastic syndromes (MDS) and post-MDS acute myeloid leukemia: information through a questionnaire survey of multi-center pilot studies in Japan

Clinico-hematologic features of myelodysplastic syndrome presenting as isolated thrombocytopenia: An entity with a relatively favorable prognosis

The existence of isolated cytopenia in myelodysplastic syndrome (MDS) has been described, however, the exact clinico-hematologic features of such MDS patients are still obscure. The aim of this study was to provide additive clinico-hematologic information on MDS patients with isolated thrombocytopenia in comparison with idiopathic thrombocytopenic purpura (ITP). We searched for MDS with isolated thrombocytopenia in 146 sequential patients with MDS and evaluated their clinical features at the time of MDS diagnosis. We found 13/146 (8.9%) patients with MDS showing isolated thrombocytopenia. These patients were male predominant (10:3) and were all diagnosed as refractory anemia after reassessment of marrow findings, however, two of them had an initial diagnosis of ITP. Leukemic transformation was rarely noted (1/13 patients), but 1 patient developed myelofibrosis. Cytogenetic study demonstrated that 3 patients had del(20q), 2 had t(1;7)(q10;p10), and 5 showed normal karyotypes. The most prominent morphologic feature in the megakaryocytes was the presence of micromegakaryocytes (5/13) and 8/13 had hypogranulated neutrophils, whereas pseudo-Pelger nuclear anomaly was rarely detectable. Of note is that 7/13 patients had an increased number of megakaryocytes in the marrow. Most patients survived for more than 2 years. Approximately 9% of MDS patients showed isolated thrombocytopenia and most of them had a favorable prognosis. Some MDS patients with isolated thrombocytopenia have been mistakenly diagnosed as having ITP, since approximately 50% of our MDS patients with isolated thrombocytopenia had an increased number of megakaryocytes with low grade dysplasia. Therefore, careful attention to differential diagnosis is recommended for these patients.

Vitamin K2 induces apoptosis of a novel cell line established from a patient with myelodysplastic syndrome in blastic transformation

We have previously reported that vitamin K2 (VK2) has a potent apoptosis inducing activity toward various types of primary cultured leukemia cells including acute myelogenous leukemia arising from myelodysplastic syndromes (MDS). We established a novel cell line, designated MDS-KZ, from a patient with MDS in blastic transformation, and further investigated the effects of VK2 using this novel cell line. MDS-KZ shows complex chromosomal anomaly including −4, 5q−, −7, 13q+, 20q−, consistent with that seen in the original patient. Culture of MDS-KZ cells in RPMI1640 medium containing 10% FBS lead to steady but very slow proliferation with a doubling time of 14 days. However, the cellular growth rate was significantly accelerated in the presence of various growth factors such as granulocyte colony-stimulating factor, stem cell factor, granulocyte–macrophage colony-stimulating factor, interleukin-3, and thrombopoietin. Most of the cultured cells show the morphological features of myeloblasts. They are positive for CD7, CD33, CD34, CD45, CD117, and HLA-DR. However, about 10% of the cells are more mature metamyelocytes and neutrophils with various dysplastic characteristics such as pseudo-Pelger nuclear anomaly and hypersegmentation, suggesting a potential for differentiation in this cell line. As previously reported for cultured primary leukemia cells, exposure to VK2, but not to VK1, resulted in induction of apoptosis of MDS-KZ cells in a dose-dependent manner (IC50: 5 μM). In addition, VK2 treatment induced down-regulation of BCL-2 and up-regulation of BAX protein expression with concomitant activation of caspase-3 (CPP32). A tetrapeptide functioning as antagonist of caspase-3, Ac-DEVD-H, suppressed the VK2-induced inhibition of cell growth, suggesting that caspase-3 is, at least in part, involved in VK2-induced apoptosis. These observations suggest that the MDS-KZ cell line can serve as a model for the study of the molecular mechanisms of VK2-induced apoptosis.

Pulmonary alveolar proteinosis as a terminal complication in myelodysplastic syndromes: a report of four cases detected on autopsy.

Secondary pulmonary alveolar proteinosis (PAP) is one of the complications of hematologic malignancy and immunosuppressive diseases. We encountered four cases of myelodysplastic syndrome (MDS) associated with PAP detected on autopsy. They consisted of two refractory anemia (RA) and two patients with refractory anemia with excess blasts in transformation (RAEBt) at the time of MDS diagnosis, but all of them developed leukemic phase and were resistant to chemotherapy at the time of pulmonary episodes. Of the four MDS patients, two also had pulmonary aspergillosis. Previously, 69 patients with PAP associated with hematologic disorders have been reported, but there have been only seven cases with MDS, including our four patients. Of the 69 reported cases of PAP in hematologic malignancies, 24/63 (38%) informative patients with infection had fungal infections of the lung; 2/7 (29%) MDS cases had fungal infection. We should, therefore, pay careful attention to this possibility in cases of MDS with lung complications, including PAP, especially in patients in the leukemic phase of MDS.

Thrombocytopenia induced by imatinib mesylate (Glivec) in patients with chronic myelogenous leukemia: is 400 mg daily of imatinib mesylate an optimal starting dose for Japanese patients?

Imatinib mesylate (Glivec) is a potent and selective inhibitor of the tyrosine kinase activity of BCR-ABL. Because the mechanism of action of imatinib mesylate is inhibition of BCR-ABL tyrosine kinase, it seems likely that to achieve maximum therapeutic benefit for chronic myelogenous leukemia (CML), imatinib mesylate must be administered at a dose that maximally inhibits BCR-ABL kinase activity or, alternatively, that inhibits sufficient BCR-ABL kinase activity to induce apoptosis. According to in vitro study results, 1 M levels of imatinib mesylate are optimal for inducing cell death, and 1 M trough levels are achieved in patients using imatinib mesylate at a daily dose of more than 300 mg [1]. In a phase I/II study in which the dose-response curve in chronic-phase CML patients was examined, the therapeutic effect was reported to plateau at a dose at or slightly above 300 mg. In addition, there was no convincing evidence of dose-limiting toxicity in patients receiving a maximum dose of 1000 mg [2]. These data were used to set the standard therapeutic dose of imatinib mesylate for chronicphase patients at 400 mg daily, and thereafter, the therapeutic benefits for CML patients of imatinib mesylate at this dose were demonstrated in clinical trials [2,3]. This standard therapeutic dose has been used in administering imatinib mesylate to Japanese patients as well as patients in the United States and Europe. At our institute, however, a series of CML patients treated with 400 mg of imatinib mesylate showed thrombocytopenia, and imatinib mesylate adminisThrombocytopenia Induced by Imatinib Mesylate (Glivec) in Patients with Chronic Myelogenous Leukemia: Is 400 mg Daily of Imatinib Mesylate an Optimal Starting Dose for Japanese Patients?

Combination of granulocyte colony-stimulating factor and low-dose cytosine arabinoside further enhances myeloid differentiation in leukemia cells in vitro.

We examined the differentiation-inducing effect on freshly isolated myeloid leukemia cells in liquid suspension culture by combined treatment with granulocyte colony-stimulating factor (G-CSF) plus low-dose cytosine arabinoside (Ara-C; 5-10 ng/ml) in 25 patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in leukemic transformation. Culture with G-CSF alone showed leukemic cell growth stimulation in 15 out of the 25 cases (60%) and induction of cell differentiation in 19 out of the 25 cases (76%), respectively. In 23 cases (92%), either growth stimulation and/or differentiation induction of leukemia cells was observed in response to G-CSF. This suggests that most myeloid leukemia cells are able to respond to G-CSF stimulation. In addition, treatment of cells with low-dose Ara-C alone resulted in the enhancement of myeloid specific antigens expression in 16 cases (64%). Treatment of leukemia cells with higher concentrations of Ara-C (over 50 ng/ml) alone resulted in cytocidal effects but not in the induction of differentiation. Furthermore, 15 cases (60%) showed pronounced myeloid differentiation of leukemia cells after combined exposure to G-CSF plus low-dose Ara-C as compared with cells treated with either G-CSF or Ara-C alone. The enhanced effect of differentiation induction by combining G-CSF plus low-dose Ara-C was also observed in a murine myeloid leukemia cell line WEHI-3B in vitro. These data suggest that treatment with G-CSF plus low-dose Ara-C is capable of inducing differentiation of leukemic cells in vitro, and also appears to be useful for the differentiation-based therapy of patients with AML and MDS.

Inhibitory effect of a nucleoside analog, acyclovir, on leukemia cells

Acyclovir (ACV), a nucleoside analog, has been demonstrated previously to suppress selectively the proliferation of NIH3T3 fibroblastic cells transformed by either v-abl or bcr-abl gene transfection. From a viewpoint of clinical application of ACV, we investigated whether ACV inhibited the growth of leukemia cells expressing either p210 BCR-ABL or p185BCR-ABL. Acyclovir exerted an inhibitory effect on OM9;22 cells, p185BCR-ABL expressing cells, in a dose-dependent manner. Despite no down-modulation of a BCR-ABL tyrosine kinase activity or its expression was observed after treatment with ACV, cell cycle analysis demonstrated synchronization of OM9;22 cells at the G0/G1 phase. This suggests that, although ACV does not directly act on BCR-ABL tyrosine kinase, ACV may exert its inhibitory effect on some leukemia cell lines via alterations of the cell cycle. Although selective inhibition of Philadelphia chromosome-positive leukemia cell growth was not apparent, our data provides a therapeutic possibility for ACV in the treatment for leukemia.

Megakaryocytic Maturation is Regulated by Maintaining a Balance Against Cytokine Induced-cell Proliferation: Steel Factor Retards Thrombopoietin-induced Megakaryocytic Differentiation While Synergistically Stimulating Mitogenesis

Using a factor-dependent cell line M07ER, which contains a stably transduced human erythropoietin (EPO) receptor gene in human megakaryoblastic cell line MO7e and which resulted in concomitant expression of EPO receptor, c-Mpl and c-Kit, we investigated the biological effects of these cytokines in terms of cell growth and differentiation. Thrombopoietin (TPO), EPO and Steel factor (SLF) all stimulated MO7ER cell proliferation in a dose-dependent manner. Combined stimulation of cells with SLF plus either TPO or EPO resulted in striking synergistic enhancement of MO7ER cell growth as compared with each cytokine alone, whereas combination of TPO plus EPO showed only an additive effect on cell proliferation. With regards to cell differentiation, either TPO or EPO treatment induced enhancement of platelet glycoprotein (GP) IIb/IIIa and GPIb expression. SLF induced GPIIb/IIIa and GPIb expression, but the effect was much weaker than that of EPO or TPO. However, addition of SLF to either TPO- or EPO- containing cultures (which induced potent mitogenesis in MO7ER cells) resulted in suppression of these megakaryocyte specific antigens. Addition of low-dose cytosine arabinoside (Ara-C)(1 to 10 ng/ml) enhanced TPO- or EPO- induced megakaryocytic differentiation in MO7ER cells while mildly suppressing cell growth. Treatment the cells with low-dose Ara-C plus TPO plus SLF overrode the proliferative enhancing effects of SLF and induced GPIIb/IIIa and GPIb expression as efficient as TPO alone. Retardation of TPO-induced megakaryocytic maturation was also observed in normal murine bone marrow cells by combined stimulation with TPO and SLF as assessed by the numbers of acetylcholinesterase staining-positive cells and megakaryocyte nuclear polyploidy. These results suggest that megakaryocytic maturation is, at least in part, regulated by countering cytokine-induced cell proliferation.