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Summary The effect of CMC-544, a calicheamicin-conjugated anti-CD22 monoclonal antibody, was analysed in relation to CD22 and P-glycoprotein (P-gp) in B-cell chronic lymphocytic leukaemia (CLL) and non-Hodgkin lymphoma (NHL) in vitro. The cell lines used were CD22-positive parental Daudi and Raji, and their P-gp positive sublines, Daudi/MDR and Raji/MDR. Cells obtained from 19 patients with B-cell CLL or NHL were also used. The effect of CMC-544 was analysed by viable cell count, morphology, annexin-V staining, and cell cycle distribution. A dose-dependent, selective cytotoxic effect of CMC-544 was observed in cell lines that expressed CD22. CMC-544 was not effective on Daudi/MDR and Raji/MDR cells compared with their parental cells. The MDR modifiers, PSC833 and MS209, restored the cytotoxic effect of CMC-544 in P-gp-expressing sublines. In clinical samples, the cytotoxic effect of CMC-544 was inversely related to the amount of P-gp (P = 0·003), and to intracellular rhodamine-123 accumulation (P

We studied the effect of CMC-544, the calicheamicin-conjugated anti-CD22 monoclonal antibody, used alone and in combination with rituximab, analyzing the quantitative alteration of target molecules, that is, CD20, CD22, CD55 and CD59, in Daudi and Raji cells as well as in cells obtained from patients with B-cell malignancies (BCM). Antibody inducing direct antiproliferative and apoptotic effect, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) were tested separately. In Daudi and Raji cells, the CDC effect of rituximab significantly increased within 12 h following incubation with CMC-544. The levels of CD22 and CD55 were significantly reduced (P

CEM, MOLT4 and SUP-B15 cells were transduced with lentivirus-mediated siRNA KIS gene. The mRNA expressions of KIS were successfully reduced in all cell lines. On the other hand, the mRNA expressions of p27(Kip1) in CEM, MOLT4 and SUP-B15 cells were not affected by the transduction with siRNA KIS gene. We showed that KIS protein directly interacted with p27(Kip1) protein, and reduction of KIS inhibited the S10 phosphorylation of p27(Kip1) in leukemia cells. On these cells transfected with siRNA KIS, the inhibition of S10 phosphorylation of p27(Kip1) was strongly suppressed cell proliferation in a time-dependent manner. Moreover, the inhibition of S10 phosphorylation of p27(Kip1) increased a significant population in G0/G1 fraction. These data demonstrated that the KIS activity was induced during G0/G1, and it promotes cell cycle progression by phosphorylation of S10 on p27(Kip1). We showed that KIS mRNA expression was increased in primary leukemia specimens (acute myelogenous leukemia (AML); 37, myelodysplastic syndrome (MDS); 72, acute lymphoblastic leukemia (ALL); 23), and the mean ratios of KIS to G3PDH in AML, MDS and ALL specimens were 3.62+/-0.68, 3.27+/-0.73 and 3.17+/-0.58, respectively. Moreover, we found that KIS protein was overexpressed in all 132 adults cases of various leukemias, including 37 AML (8 M1, 12 M2, 2 M3, 7 M4, 8 M5), 72 MDS (42 RAEB-I, 30 REAB-II) and 23 ALL (23 L2). This study demonstrates that the elevated levels of KIS protein in leukemia cells promote the cell cycle progression in leukemia cells.

[Background] Homeobox (Hox) genes are grouped together in 4 clusters, A to D. Recent studies has shown that the Hox proteins are important in the control of differentiation and proliferation in hematopoietic cells. We found that the Abl kinase inhibitors increased the expression of HoxA10 gene in CML cells. In this study, we analyzed the role of HoxA10 in CML cell lines and the hematopoietic progenitor cells derived from CML patients by inhibiting the expression of HoxA10. Moreover, we investigated whether the regulation of HoxA10 eradicate Ph+ hematopoietic stem/progenitor cells, which are the targets for leukemic transformation in CML. [Methods] We used AMN107 and BMS354825 for the Abl kinase inhibitors, LY294002 for a PI3K inhibitor, PP2 for a Src kinase inhibitor, and SB203580 for a p38 MAP kinase inhibitor. For analysis of HoxA10 mRNA and protein, RT-PCR and western blot were performed in K562, Meg-01 and U937 cells, which untreated or treated with AMN107, BMS354825, LY294002, PP2, or SB203580 respectively. We then attempted to localize the intracellular locations of HoxA10 in K562 and Meg01, which untreated or treated with AMN107, BMS354825, or LY294002 by using conforcal fluorescence microscopy. For analysis of proliferation in K562, Meg-01 and U937 transfected with siRNA HoxA10, MTT assays were performed in untransfected or transfected K562, Meg-01 and U937 treated with or without AMN107, BMS354825, or LY294002. Finally, we counted the colony numbers of CFU-GEMM, CFU-GM, and BFU-E in K562 and Meg-01 treated with the Abl kinase inhibitors or LY294002. Results Both K562 and Meg01 cells expressed HoxA10 mRNA and protein at lower level compared to U937 cells. Interestingly, treatment with AMN107, BMS354825, or LY294002 increased the expression of HoxA10 mRNA and protein in both K562 and Meg01 cells. The fluorescence of HoxA10 was more strongly observed in the area corresponding to the cell’s cytoplasm than nucleus, and the treatment with AMN107, BMS354825, or LY294002 increased the fluorescence in nucleus of K562 and Meg01 cells in a time-dependent manner. In K562 and Meg01 cells transfected with the siRNA HoxA10, treatment with AMN107 or BMS354825 slightly inhibited the proliferation compared to K562 and Meg01 transfected with control siRNA. Finally, we showed that the inhibition of HoxA10 expression by siRNA increased the numbers of CFU-GEMM, BFU-E, and CFU-GM when the cells were treated with the combination of BMS354825 and LY294002 compared to control cells. [Conclusions] In this study, we showed that the Abl kinase inhibitors induced the expression of HoxA10, and HoxA10 was regulated by PI3K pathway in CML cells. This finding indicates a new insight in the regulation of cell proliferation via the PI3K signal pathway in CML cells. Moreover, we found the role of HoxA10 in CML cell lines and the hematopoietic progenitor cells derived from CML patients by inhibiting the expression of HoxA10. We showed that the regulation of HoxA10 eradicated Bcr-Abl+ hematopoietic stem/progenitor cells, which are the targets for leukemic transformation in CML.

We describe 2 patients with acute promyelocytic leukemia (APL) in whom torsade de pointes (TdP) developed during treatment with arsenic trioxide. Patient 1 was a 23-year-old woman with second-relapse APL. Ventricular premature beat bigeminy developed on day 27 of treatment, and episodes of TdP developed on day 28. Patient 2 was a 51-year-old woman with second-relapse APL who had cardiomyopathy due to prior anthracycline treatment. TdP developed on day 17 of treatment. Arsenic trioxide is known to cause electrocardiographic abnormalities, such as ventricular tachycardia and prolongation of QT interval. Patient 1 was given fluconazole as a concomitant drug. Patient 2 had cardiomyopathy and hypokalemia. Careful management is needed during arsenic trioxide therapy because this treatment prolongs the QT interval, possibly inducing episodes of TdP.

Acute promyelocytic leukemia (APL) cells express a considerable level of CD33, which is the target of gemtuzumab ozogamicin (GO), and a significantly lower level of P-glycoprotein (P-gp). Therefore, GO is predicted to be a successful treatment for APL. In this article, we report on the GO treatment of 2 patients with APL, who had fully relapsed after induction therapy with all -trans retinoic acid (ATRA) following chemotherapy. Both patients had relapsed 3 times and were resistant to reinduction therapy with ATRA. GO (9 mg/m2) was administered on days 1 and 15. After GO treatment, both patients achieved complete hematologic and molecular remission. GO may be another promising agent for the treatment of ATRA-resistant relapsed APL when given as salvage chemotherapy.

Acute promyelocytic leukemia (APL) cells express a considerable level of CD33, which is a target of gemtuzumab ozogamicin (GO), and a significantly lower level of P-glycoprotein (P-gp). In this study, we examined whether GO was effective on all-trans retinoic acid (ATRA)- or arsenic trioxide (ATO)-resistant APL cells. Cells used were an APL cell line in which P-gp was undetectable (NB4), ATRA-resistant NB4 (NB4/RA), NB4 and NB4/RA that had been transfected with MDR-1 cDNA (NB4/MDR and NB4/RA/MDR, respectively), ATO-resistant NB4 (NB4/As) and blast cells from eight patients with clinically ATRA-resistant APL including two patients with ATRA- and ATO-resistant APL. The efficacy of GO was analyzed by (3)H-thymidine incorporation, the dye exclusion test and cell cycle distribution. GO suppressed the growth of NB4, NB4/RA and NB4/As cells in a dose-dependent manner. GO increased the percentage of hypodiploid cells significantly in NB4, NB4/RA and NB4/As cells, and by a limited degree in NB4/MDR and NB4/RA/MDR cells. Similar results were obtained using blast cells from the patients with APL. GO is effective against ATRA- or ATO-resistant APL cells that do not express P-gp, and the mechanism of resistance to GO is not related to the mechanism of resistance to ATRA or ATO in APL cells. Leukemia (2005) 19, 1306-1311. doi:10.1038/sj.leu.2403807; published online 26 May 2005.

Adeno-associated virus (AAV) vector system has several useful advantages with regard to in vitro and in vivo gene transfer. However, their usages have been limited by cumbersome and labor-intensive vector production in the traditional method. To overcome limitations in AAV production, in this report, we explored the possibility of generating AAV packaging cell line, 293T R/C.VA.E2A.E4. cells, by using lentivirus-mediated transduction of Rep/Cap gene of AAV-2, VA RNA, E2A, and E4 genes of Ad5 into 293T cells. In packaging cell lines, it is important that supply of the AAV vector can be stably performed for long time. We showed that the 293T R/C.VA.E2A.E4. cells have stably maintained the transduced components after more than 10 passages and yielded high-titer AAV vectors, and the titer of AAV vectors did not decline even if culture of the packaging cells was continued for long time. The Rep/Cap and E4 gene products caused no remarkable cytotoxicity. The 293T R/C.VA.E2A.E4. cells might be able to tolerate the Rep/Cap and E4 gene products, or have less copy numbers of the Rep/Cap and E4 genes than the traditional method. Moreover, we showed that the AAV vectors derived from 293T R/C.VA.E2A.E4. cells infected the primary human CD34+ haematopoietic progenitor cells with high efficiency (50-70%). In the 293T R/C.VA.E2A.E4. cells, the AAV vectors can be generated by the transfection of one AAV vector plasmid, and large-scale AAV production can be easily achieved. It is important that cumbersome, variable, and costly transfection is avoided.

We studied the cytotoxic effect of an organic arsenical compound, phenylarsine oxide (PAO) on an acute promyelocytic leukemia (APL) cell line (NB4) and an As2O3-resistant NB4 subline (NB4/As). Cell growth was inhibited by 50% (IC50) upon 2-day treatment with As2O3 or PAO at 0.54 and 0.06 microM, respectively in NB4 cells (P = 0.025), and 2.80 and 0.08 microM, respectively in NB4/As (P = 0.030). 0.1 microM PAO increased the proportion of hypodiploid cells (50.3%) by a greater degree than the same dose of As2O3 (3.8%) in NB4 cells. In NB4 cells, 0.1 microM PAO reduced the mitochondrial transmembrane potential (20.5% in a PI(negative)-Rhodamine123(low) fraction) by a greater degree than 1 microM As2O3 (7.1%). Western blotting showed that 0.1 microM PAO downregulated the expression of both Bcl-2 and Bcl-X(L) proteins, whereas I microM As2O3 downregulated only Bcl-2 expression. These results suggest that the cytotoxic effect of PAO on an APL cell line and As2O3-resistant subline is significantly higher than that of As2O3. PAO-induced apoptosis seems to be related to the activation of the mitochondrial pathway and downregulation of both Bcl-2 and Bcl-X(L). PAO is a considerable agent for relapsed/refractory APL and for purging APL cells following stem cell transplantation.

Gemtuzumab ozogamicin (CMA-676), a calicheamicin-conjugated humanized anti-CD33 mouse monoclonal antibody, has recently been introduced clinically as a promising drug for the treatment of patients with acute myeloid leukemia (AML), more than 90% of which express CD33 antigen. However, our recent study suggested that CMA-676 was excreted by a multi- drug-resistance (MDR) mechanism in P-glycoprotein (P-gp)-expressing leukemia cell lines. We analyzed the in vitro effects of CMA-676 on leukemia cells from 27 AML patients in relation to the amount of P-gp, MDR-associated protein 1 (MRP1), CD33 and CD34, using a multi-laser-equipped flow cytometer. The cytocidal effect of CMA-676, estimated by the amount of hypodiploid portion on cell cycle, was inversely related to the amount of P-gp estimated by MRK16 monoclonal antibody (P = 0.004), and to the P-gp function assessed by intracellular rhodamine-123 accumulation in the presence of PSC833 or MS209 as a MDR modifier (P = 0.0004 and P = 0.002, respectively). In addition, these MDR modifiers reversed CMA-676 resistance in P-gp-expressing CD33(+) leukemia cells (P = 0.001 with PSC833 and P = 0.0007 with MS209). In CD33(+) AML cells from 13 patients, CMA-676 was less effective on CD33(+)CD34(+) than CD33(+)CD34(-) cells (P = 0.002). PSC833 partially restored the effect of CMA-676 in CD33(+)CD34(+) cells. These results suggest that the combined use of CMA-676 and a MDR modifier will be more effective on CD33(+) AML with P-gp-related MDR.

Recent studies have shown that arsenic trioxide (As(2)O(3)) can induce complete remission in patients with acute promyelocytic leukemia (APL). We tested the efficacy and safety of As(2)O(3) for the treatment of patients with APL who had relapsed from or become refractory to all-trans retinoic acid (ATRA) and conventional chemotherapy in a prospective study. As(2)O(3) at a dose of 0.15 mg/kg was administered until the date of bone marrow remission to a maximum of 60 days. In patients who achieved complete remission (CR), one additional course of As(2)O(3) was administered using the same dose for 25 days. Of 14 patients, 11 (78%) achieved CR. Six of 10 patients who achieved CR showed disappearance of PML-RARalpha transcript by RT-PCR assay. The duration of As(2)O(3)-induced CR ranged from 4 to 22 months (median, 8 months) at a median follow-up of 17 months. Adverse events included 13 electrocardiogram abnormalities (13 QTc prolongation, eight ventricular premature contraction, four nonsustained ventricular tachycardia and two paroxysmal supraventricular tachycardia), seven nausea and vomiting, four pruritus, three peripheral neuropathy, three fluid retention and one APL differentiation syndrome. Four patients received antiarrhythmic agents. Hyperleukocytosis developed in five patients and in three cytotoxic drugs were necessary. Other adverse events were relatively mild. As(2)O(3) treatment is effective and relatively safe in relapsed or refectory patients with APL. Cardiac toxicities in patients with QTc prolongation should be carefully monitored.

Erythropoietin (Epo) is one of the main regulators of growth and differentiation of hematopoietic cells. In normal bone marrow cells, the amount of erythropoietin receptor (EpoR) was highest in the CD34+ CD38- subset, and decreased on lineage committed progenitor cells expressing CD38 antigens. Among the erythroid cells expressing GpA antigens, CD34-positive fractions expressed more EpoR than CD34-negative fractions. Although the amounts of EpoR of bone marrow cells from patients with refractory anemia (RA) were less than those of normal bone marrow cells in all phenotypes examined, there was no statistical significant difference. EpoR was detected on leukemia cells from 60% of acute myeloblastic leukemia (AML) cases and 29% of acute lymphoblastic leukemia (ALL) cases, and distributed widely among all FAB-subtypes. In spite of the presence of EpoR, in vitro proliferative response to Epo was not observed in a large proportion of AML. And there was no correlation between the amount of EpoR and the in vitro response to EPO. Patients with both EpoR expression and in vitro response to Epo had shorter remission duration than those without EpoR.

Using a non-isotopic ligand binding assay and immunofluorescence, we examined the amount of mpl, glycoprotein IIb/IIIa (gpIIb/IIIa) and glycoprotein Ib (gpIb) on platelets from healthy volunteers and patients with refractory anemia (RA). For the analysis of mpl expression, we applied both a non-isotopic ligand binding assay and immunofluorescence using anti-mpl monoclonal antibody, and compared the results from both methods. The non-isotopic ligand binding assay has been developed in our laboratory and is suitable for the quantitative analysis of a small amount of cytokine receptors such as mpl on platelets. In platelets from patients with RA, the amount of mpl expressed by the D value was 0.05+/-0.03 (mean+/-standard deviation), and was significantly lower than that in healthy volunteers (0.15+/-0.05, p

Calicheamicin-conjugated humanized anti-CD33 mouse monoclonal antibody, CMA-676, has recently been introduced to clinics as a promising drug to treat patients with acute myeloid leukemia (AML) in relapse. However, the mechanism of action of CMA-676 has not been well elucidated. The cytotoxic effect of CMA-676 on HL60, NOMO-1, NB4, NKM-1, K562, Daudi, and the multidrug-resistant sublines, NOMO-1/ADR and NB4/MDR, was investigated by cell cycle distribution and morphology. These studies were done by a video-microscopic system, DNA fragmentation, dye exclusion and 3H-thymidine uptake after analysis of CD33, CD34, P-glycoprotein (P-gp), multidrug resistance (MDR)-associated protein and lung-related protein on these cells. A dose-dependent, selective cytotoxic effect of CMA-676 was observed in cell lines that expressed CD33, and was dependent on the amount of CD33 and the proliferative speed of the cells. Sensitive cells were temporally arrested at the G2/M phase before undergoing morphological changes. CMA-676 is not effective on P-gp-expressing multidrug-resistant sublines compared with parental cell lines. MDR modifiers, MS209 and PSC833, restored the cytotoxic effect of CMA-676 in P-gp-expressing sublines. CMA-676 is a promising agent in the treatment of patients with AML that expresses CD33. The combined use of CMA-676 and MDR modifiers may increase the selective cytotoxic effect in multidrug-resistant AML.

We studied serum thrombopoietin (TPO) levels and circulating numbers of platelet during five courses of myelosuppressive post-remission chemotherapy in three patients with acute leukemia in complete remission. Serum TPO levels were measured by a newly developed and sensitive sandwich enzyme-linked immunosorbent assay. In all courses, serum TPO levels changed reciprocally with the platelet counts. When platelets were transfused into patients near the time of platelet nadir, the TPO levels dropped temporarily, while platelet counts temporarily increased. In addition, platelets obtained after transfusion in a thrombocytopenic patient showed lower binding to biotinylated TPO than donor platelets prior to the transfusion. The finding indicated that the TPO receptors were saturated with endogenous TPO of the patient with a high serum TPO level. These results suggest that the platelet mass directly regulates serum TPO levels by receptor-mediated absorption and is one of the major regulators of serum TPO levels in humans.

Using a non-isotopic ligand binding assay, we quantitatively examined the amount of human thrombopoietin (TPO) receptor (TPO-R) on leukaemia cells from 128 patients with acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL). The TPO-R was expressed in 53 (47%) of 114 AML cases, and an in vitro treatment with TPO led to proliferation (stimulation index >1 5) of leukaemia cells in 13 (20%) of 66 AML cases examined. The TPO levels had no relation to the FAB classification except for FAB-M7 AML. All five FAB-M7 cases expressed TPO-R, and one of three FAB-M7 examined showed in vitro proliferative response to TPO. Although there was no significant correlation (r = 0.3125) between the amount of TPO-R and the proliferative response, all of the AML cases which showed the in vitro response had TPO-R expression. There was no relationship between TPO-R amount and CD phenotypes, or the amount of granulocyte-colony stimulating factor (G-CSF) receptor. TPO-R was also expressed in two (14%) of 14 cases of ALL, and only these two cases had in vitro proliferative response to TPO. One had only lymphoid antigens, and the other had both lymphoid and myeloid antigens. Our results suggest that some leukaemia cells express functionally active TPO-R.

Using a non-isotopic ligand binding assay using multi-colour flow cytometry, we quantitatively examined the amount of mpl in megakaryocyte-platelet lineage cells. Firstly, we quantified the amount of mpl on cell lines. Mpl gene-transfected BaF3 cells expressed a large amount of mpl, whereas original BaF3, K562, HL-60 and NOMO-1 cells showed no mpl. In bone marrow cells from healthy volunteers, mpl was expressed on CD34 + cells from the very early stage of differentiation when they had no CD38 antigen. The amount of mpl increased with differentiation to CV34 + CD41 + cells, but decreased with further differentiation to CD34 + CD41 + cells. In CD34 + CD41 + cells the amount of mpl varied according to cell size: abundant in large cells, moderate in medium-size cells and a little in small cells. In bone marrow cells from patients with refractory anaemia (RA), the amount of mpl was decreased compared with that in bone marrow cells from healthy volunteers. When analysed by the same CD phenotype and same cell size, the amount of mpl was less in RA patients compared with that in healthy volunteers in all phenotypes and sizes tested. The proportion of large CD34 + CD41 + cells was less in RA patients than in normal volunteers.

In order to develop a non-isotopic quantitative assay of erythropoietin (Epo) receptor (EpoR) on human cells, we devised a flow-cytometric assay using cells stained with biotin-labelled and a streptavidine-RED670 conjugate. For quantification, we applied the Kolmogorov-Smirnov test and calculated the D value. The D value was evaluated from the degree of shift in two profiles according to the increase of fluorescence intensity due to the specific binding of biotin-labelled Epo to EpoR. A good correlation was observed between the number of EpoR calculated by 125I-Epo binding assay and the D value. Then, EpoR expression on bone marrow cells from normal individuals was studied by three-colour flow cytometry. In normal bone marrow, the number of EpoR on cells was highest in CD34+CD38 cells (approximately 1600 sites/cell), and decreased in the following order: CD34+CD38- cells > CD34+CD38+ cells > CD34-CD38+ cells. Glycophorin A (GpA) positive erythroid cells also expressed EpoR, and their CD34+ fraction expressed more EpoR than their CD34- fraction. However, the expression levels of EpoR of these fractions were lower than CD34+CD38- cells. These results indicated that EpoR was highly expressed on CD34+ haemopoietic progenitors from very early stages of differentiation without expression of CD38 antigen, and that the level of expression decreased with erythroid differentiation as well as with various lineage commitment in human bone marrow cells.

P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) are induced by arsenic trioxide (As 2 O 3 ), but are not the main mechanism of As 2 O 3 -resistance in acute promyelocytic leukemia cells

Recently, arsenic trioxide (ATO) has been proved to induce complete remission (CR) at a high rate in patients with acute promyelocytic leukemia (APL). We prospectively investigated the safety and efficacy of ATO therapy in patients with relapsed and refractory APL and examined the duration of CR and the postremission therapies. Initially, 0.15 mg/kg ATO was administered until bone marrow remission to a maximum of 60 days. After the patient achieved CR, 1 additional ATO course at the same dosage was administered for 25 days. Of 34 patients, 31 (91%) achieved CR. PML-RAR3 messenger RNA was not detected in the bone marrow of 18 (72%) of the 25 patients evaluated by reverse transcriptase-polymerase chain reaction analysis. At a median follow-up of 30 months, the estimated 2-year overall survival rate was 56%, and the estimated 2-year event-free survival rate was 17%. During the ATO therapy, QTc prolongation was observed in most cases. Fifteen patients developed ventricular tachycardia, and 1 of them showed torsades de pointes. Other adverse events were nausea, water retention, APL differentiation syndrome, skin eruption, liver dysfunction, and peripheral neuropathy, all of which were quite tolerable. ATO therapy was remarkably effective for relapsed APL; however, postremission therapies were necessary to maintain a durable remission.

Objectives Several studies including ours have suggested that lack of CD56 in multiple myeloma (MM) defines a unique patient subset with poorer prognosis. However, the mechanism underlying this aggressive behavior of CD56 − MM has not been well elucidated. Interleukin-6 (IL-6) or insulin-like growth factor I (IGF-I) induce proliferation of MM cells. In this study, we report about the relationship between CD56 expression and responsiveness to these cytokines. Methods We sorted out both CD56 − and CD56 + fractions from MM cell lines such as KMS-21-BM and U-266, and investigated their different responsiveness to IL-6 or IGF-I. Furthermore, we compared the effects of these cytokines on the regulation of cell-cycle distribution between CD56 − and CD56 + cells. Results Although CD56 − cells in both KMS-21-BM and U-266 cells responded significantly to IL-6, CD56 + cells did not. Ki-67 + cells in the CD56 − cells were significantly increased by IL-6. Western blotting showed that IL-6 phosphorylated Akt, and upregulated and downregulated the level of cyclin D1 and p27 protein in the CD56 − KMS-21-BM cells, respectively. LY-294002 completely blocked these effects of IL-6. On the other hand, Ki-67 + cells in the CD56 + cells did not respond to IL-6. Anti-IGF-I mAb significantly reduced Ki-67 + cells only in the CD56 + cells. IGF-I phosphorylated Akt and upregulated cyclin D1 in the CD56 + KMS-21-BM cells, which was completely blocked by LY294002. Conclusions These results suggest that CD56 − and CD56 + MM cells could be stimulated by IL-6 and IGF-I, respectively, via PI3-K/Akt pathway, and provide useful information for anticytokine therapies.

Cyclooxygenase-2 (COX-2) is reported to be an important cellular target for therapy in malignancies. The growth inhibitory effects of COX-2 inhibitors on malignancies have been demonstrated to be through not only COX-2 dependent, but also independent mechanisms. In this study, we showed that etodolac, COX-2 inhibitor, induced apoptosis via COX-2 independent pathway, and investigated the molecular details of etodolac-induced apoptosis in Burkitt's lymphoma cells. In Daudi and Raji Burkitt's lymphoma cell lines, which expressed no COX-2 enzyme, etodolac more strongly induced apoptosis compared to meloxicam. Moreover, etodolac did not induce apoptosis to normal B-lymphocytes. For the pathway of etodolac-induced apoptosis, reduction of anti-apoptotic bcl-2 mRNA and Bcl-2 protein, activation of Caspase-9 and -3, down-regulation of caspase inhibitors, c-IAP-1 and Survivin were involved. Moreover, EBER-1 and -2 expression in Epstein–Barr virus positive Daudi and Raji cells were reduced to result in down-regulation of Bcl-2 by treatment with etodolac. It has been reported that etodolac has stereoisomers, R- and S-etodolac. We found that racemate of etodolac more strongly induced apoptosis in Daudi and Raji cells compared to R- or S-etodolac. In conclusion, our findings indicated etodolac inhibited EBERs expression and induced apoptosis via a Bcl-2-regulated pathway. Moreover, racemate of etodolac more effectively induced apoptosis than R- and/or S-etodolac. Therefore, these activities of etodolac potentially extend to the treatment of patients with Burkitt's lymphoma resistant to chemotherapy.

Here the relationship between all-trans retinoic acid (ATRA)-resistance and P-glycoprotein (P-gp)-associated multidrug resistance (MDR) is discussed in acute promyelocytic leukemia (APL). First, the remission rates of ATRA therapy are similar in relapsed/refractory APL to the preceding chemotherapy given and in newly diagnosed APL. Second, MDR1 cDNA-transduced NB4 (NB4/MDR) cells accumulate less Rhodamine-123 (Rh123) than NB4 cells, but there is no difference in the intracellular ATRA concentration between them. PSC833 or MS209. MDR modifiers, increases the intracellular accumulation of Rh123 in NB4/MDR and APL cells expressing P-gp, but not of ATRA. Third, the expression of CD11b, the NBT reduction activity, the proportion of apoptotic cells and the morphology are not different between NB4/MDR and NB4 cells, and between APL cells expressing P-gp and not. APL cells express little P-gp, and mainly express CD33 but no CD34. Despite previous reports that ATRA-resistant APL cells express more P-gp than ATRA-sensitive ones, P-gp and ATRA-resistance seems to exist independently.

Interleukin-12 (IL-12) has potent antitumor activities. We examined whether IL-12 enhanced the cytotoxicity of peripheral blood mononuclear cells (PBMNC) and decreased leukemia cells in 30 patients with leukemia or myelodysplastic syndromes (MDS): 12 acute myeloid leukemia (AML) (five in complete remission (CR) and seven in non-CR); six chronic myeloid leukemia (CML); and 12 MDS (three refractory anemia (RA), eight RA with excess of blasts and one chronic myelomonocytic leukemia). PBMNC from patients and five healthy volunteers were cultured at 5 x 10(5)/ml parallel with or without 100 units/ml of IL-12 for 3 days. Cytotoxicity of PBMNC against K562 cells was assessed by flow cytometry. To quantify the amount of leukemia cells, WT1 mRNA was measured by competitive reverse transcription polymerase chain reaction (RT-PCR), since WT1 mRNA is considered as a marker of minimal residual disease (MRD) in leukemia or MDS. The cytotoxicity of non-IL-12-treated PBMNC of 30 patients was 13.4+/-9.3% at the effector to target (E:T) ratio of 20:1, and significantly lower than that of normal subjects (25.7+/-8.4%). The cytotoxicity increased to 30.6+/-17.9% in the IL-12-treated PBMNC. WT1 mRNA in PBMNC of five healthy volunteers was less than 10(3) copies/microg of total RNA. Following the 3-day IL-12 treatment, mean WT1 mRNA of PBMNC was reduced from 10(4.8) to 10(4.2) copies/microg of total RNA in six CML patients, from 10(5.4) to 10(4.8) copies/microg in 12 MDS patients and from 10(5.0) to 10(4.2) copies/microg in five AML patients in CR, but not reduced in five of seven AML in non-CR. These results showed that IL-12 significantly enhanced PBMNC cytotoxicity and decreased the quantity of leukemia cells in PBMNC of most patients with MDS, CML and AML in CR. IL-12 might be of considerable benefit in the elimination of MRD in patients with hematological malignancies.

We analysed the relationship between all-trans retinoic acid (ATRA) resistance and P-glycoprotein (P-gp)-associated multidrug resistance (MDR) in acute promyelocytic leukaemia (APL). There was no difference in the intracellular ATRA accumulation between NB4 cells and an MDR1 cDNA-transduced NB4 subline and between ATRA-resistant NB4 cells (NB4/RA) and an MDR1 cDNA-transduced NB4/RA subline. PSC833, a MDR modifier, did not increase the intracellular accumulation of ATRA or affect the expression of CD11b, the nitroblue tetrazolium (NBT) reduction activity, the proportion of apoptotic cells or the morphology of these four ATRA-treated cell lines. Similar results were obtained in the analysis of APL cells from five patients relapsed after ATRA-induced complete remission.

Expression of erythropoietin (EPO) receptor (EPO-R) was analysed in leukaemia cells from 150 patients with acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL). EPO-R was expressed in 81 (60%) out of 136 AML, and in vitro treatment with EPO led to proliferation of leukaemia cells in 13 (16%) out of 81 AML examined. EPO-R expression and in vitro response to EPO were observed in all subtypes of AML according to the French-American-British (FAB) classification. All eight patients with FAB-M6 expressed EPO-R, and one out of four showed an in vitro response to EPO. Although there was no significant correlation (r = 0.2522) between the amount of EPO-R and the in vitro response to EPO, all of the AML patients who showed in vitro response expressed EPO-R. Stem cell factor significantly enhanced both EPO-R expression and in vitro response to EPO. Interleukin-3 tended to increase in vitro response to EPO. CD phenotypes, the amount of granulocyte colony-stimulating factor (G-CSF) receptors and the amount of TPO receptors had no significant relationship with the amount of EPO-R. Patients with both EPO-R expression and in vitro response to EPO had shorter duration of complete remission than those without EPO-R (P = 0.0053). EPO-R was expressed in four (29%) out of 14 ALL, and none out of five ALL showed in vitro response to EPO.

Granulocyte colony-stimulating factor (G-CSF) is the most important cytokine in granulopoiesis, and induces the proliferation and differentiation of normal bone marrow granulocytic precursors. The physiologic effect of G-CSF is mediated through binding to specific cell surface receptors for G-CSF. Using a newly-devised quantitative flow-cytometric assay, we analyzed the expression of G-CSF receptors on normal and leukemic hematopoietic cells. In normal donors, G-CSF receptors are widely expressed from CD34-positive immature bone marrow cells to mature peripheral granulocytes. The highest expression of G-CSF receptors is observed in peripheral granulocytes. In the bone marrow, the level of G-CSF receptors expression increases in the following order; CD34+ CD33- cellsCD34+ CD33+ cellsCD34- CD33+ cells, indicating that G-CSF receptors are expressed on myeloid cells from a very early stage of differentiation and that the level of expression increases with the progress of cell maturation. G-CSF receptors are also detected on blast cells of patients with acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). The number of cell surface receptors varies from patient to patient, and no clear correlation is observed between the expression of receptors and the leukemia subtype or the cell surface markers. In this respect, the clinical use of G-CSF should be carefully controlled in ALL as well as AML patients.

We examined the multidrug resistant P-glycoprotein (P-gp) on normal bone marrow (BM) cells and acute myeloid leukaemia (AML) cells, using newly devised flow cytometric multi-parameter analysis with CD33, CD34 and MRK16 monoclonal antibodies. In both normal BM cells and AML cells, CD34 + CD33 - cells expressed P-gp strongly, CD34 + CD33 + cells moderately, and CD34 - CD33 + cells weakly. Acute promyelocytic leukaemia, mainly expressing CD34 - CD33 + but not CD34 + CD33 - at diagnosis, expressed less P-gp. P-gp expression of AML cells at diagnosis was increased as compared with normal cells of the same phenotype. P-gp expression was more increased in relapsed cases, especially in immature subpopulations.

Impairment of heart rate variability control during arsenic trioxide treatment for acute promyelocytic leukemia

Abstract 2182 Poster Board II-159 Objective PHLPP1 and 2 (pleckstrin homology (PH) domain leucine-rich repeat protein phosphatase 1 and 2) is identified as the dephosphorylation enzyme of Akt, the same as that of PP2A of the dephosphorylation enzyme of Akt, and regulate the cell-growth signal of Akt through a dephosphorylation of the phosphorylated Akt (p-Akt). Previously, we reported the expression of PHLPP1 and 2 were suppressed in CML cell lines. In this study, we investigated the the CML and its progenitor cell proliferation through the phosphorylation of Akt by depletion of PHLPP1 and 2. Method CML cell lines (K562, Meg01, SHG3) and the CML clinical specimen (n= 10) were used for this research. The changes in the expression of PHLPP1 and 2 by treatment with Abl kinase inhibitors (STI571, AMN107 and BMS354825) or knock down with Bcr-Abl gene were evaluated by RT-PCR method. The influence on the expression of PHLPP1 and 2 in AML cell line transfected with Bcr-Abl also evaluated. CML progenitor cells derived from CML patients separated by ALDH activity, and the expression of PHLPP1 and 2 were investigated by quantitative RT-PCR method. p-Ser473 Akt1, 2 and 3 by Abl kinase inhibitor or knock down with PHLPP1 and 2 were measured, and the influence on the effect of cell growth inhibition by MTT assay. The expression of PHLPP1 and 2 and colony formation in colony forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), colony forming unit-granulocyte, macrophage (CFU-GM) and burst forming unit-erythroid (BFU-E) derived from Bcr-Abl positive hematopoietic progenitor cells also evaluated. Result The expression of mRNA and protein of PHLPP1 and 2 were increased by treatment with Abl kinase inhibitor or Bcr-Abl knock down by siRNA in CML cell lines and AML cell line trasfected with Bcr-Abl gene. Moreover, p-Ser473 Akt 2 and 3 were decreased according to the expression of PHLPP1, and also p-Ser473 Akt1 and 3 according to the expression of PHLPP2. The Abl kinase inhibitors induced the expression of PHLPP1, 2 and the reduction of p-Ser473 Akt isoforms. The Abl kinase inhibitors inhibited the CML cell proliferation via the depletion of PHLPP1 and 2. In Bcr-Abl positive progenitor cells, the expression of PHLPP1 and 2 was increased, and colony formation was suppressed by Abl kinase inhibitor and by Bcr-Abl siRNA. The colony formation in progenitor cells knocked down PHLPP1 and 2 were decreased when treated with Abl kinase inhibitors. Conclusion These results suggest that Bcr-Abl might promote CML cell proliferarion through continuous phosphorylation of p-Ser473 Akt1, 2 and 3 by suppression of PHLPP1 and 2, and that the induction of PHLPP1 and 2 may be effective to regulate the cell proliferation in CML cells. It may be also that the induction of expression of PHLPPs has the potential possibility as the targets on the regulation of cell proliferation in Bcr-Abl positive progenitor cells. Disclosures: No relevant conflicts of interest to declare.

Abstract 4814 Background and Aims We synthesized two phospha sugar derivatives, 2,3,4-tribromo-3-methyl-1-phenylphospholane 1-oxide (TMPP) by reacting 3-methyl-1-phenyl-2-phospholene 1-oxide with bromine, and we has reported their potential as an antileukemic agent in cell lines. In this study, we have investigated that TMPP have antileukemic effects as shown in various leukemia cell lines as well as primary AML patient specimens. Moreover, we have identified the target molecules of TMPP by using docking simulation. Methods In human leukemia cell lines (HL60, NB4, U937, NOMO-1, CEM, MOLT4, SUP-B15, and YRK2 cells), the anti-leukemic effects were elevated by cell proliferation assay, Cell cycle analysis, Western blotting. In AML cells derived from AML patients and normal hematopoietic progenitor cells derived from healthy volunteers, the changes of viability by treatment with TMPP were evaluated. By using docking simulation, the target molecules were identified in leukemia cells treated with TMPP. Results TMPP showed inhibitory effects on leukemia cell proliferation, with mean IC50 values of 10.2 nmol/L for TMPP, indicating that inhibition appeared to be dependent on the number of bromine atoms in the structure. Further, TMPP at 8.4 nmol/L induced G2/M cell cycle block in leukemia cells, and TMPP at 17.3 nmol/L induced apoptosis in these cells. TMPP treatment reduced cell cycle progression signals (FoxM1, KIS, Cdc25B, Cyclin D1, Cyclin A, and Aurora-B) and tumor cell survival (Bcl-2, p27Kip1 and p21Cip1). Further, treatment with TMPP significantly reduced the viability of AML specimens derived from AML patients, but only slightly reduced the viability of normal ALDHhi progenitor cells. We also found that TMPP showed the strong activity against Aurora kinase B and Bcl-2 by using docking simulation. Conclusion We demonstrate that TMPP inhibits Aurora kinase B and Bcl-2 and shows a dominant Aurora B kinase inhibition-related cell cycle arrest and the induction of mitochondrial potential catastrophe-related apoptosis in acute leukemia cells. Moreover, we identified Aurora kinase B and Bcl-2 as the target molecules of TMPP. We conclude that TMPP has great therapeutic potential in anticancer therapy in a wide range of cancers. Disclosures: No relevant conflicts of interest to declare.

[Background] The proto-oncogene Akt/PKB is activated in many human cancers including leukemias, and regulates the cell survival and apoptosis. Akt/PKB is activated by growth factors or the phosphatidylinositol-3,4,5-triphosphate via PI3K, phosphorylates many substrates for cell survival or proliferation. The tumor suppressor PTEN prevents Akt/ PKB phosphorylation and activation. On the other hand, the PH domain leucine-rich repeat protein phosphatase (PHLPP) dephosphorylates Akt/PKB, induces apoptosis, and suppresses tumor growth. It has been reported that the expression levels of PHLPP are significantly reduced in several colon cancer and glioblastoma cell lines, and Akt/PKB phosphorylation is elevated. However, its function is little known in CML. We found that the expression of PHLPP gene and protein was suppressed in CML cells. In this study, we have investigated the expression and the function of the PHLPP in CML cells. [Methods] The cells used in this study were human CML cell lines, K562 and Meg01 cells. Primary CML (CP; n=10) cells were obtained from the peripheral blood or bone marrow. Human normal mononuclear cells (MNCs) were isolated from peripheral blood or bone marrow of healthy volunteers after obtaining informed consents. For analysis of PHLPP mRNA expression, quantitative RTPCR was performed in all cell lines treated with Abl kinase inhibitors (STI571, AMN107, and BMS354825). For proliferation analysis and the levels of Akt phosphorylation in CML cells, MTT assays and western blot were performed in all cell lines transfected with Bcr-Abl or PHLPP siRNA, respectively. For colony analysis, the colonies of CFU-GEMM, CFUGM, and BFU-E were counted in CML stem/progenitor cells transfected with PHLPP siRNA or treated with Abl kinase inhibitors. [Results] In CML cell lines, the expressions of PHLPP mRNA and protein were significantly increased more than normal MNCs by treatment with Abl kinase inhibitors or transfection with Bcr-Abl siRNA. On the other hands, in CML cells transfected with the PHLPP siRNA, it is shown that the phosphorylation levels of Akt were markedly increased compared to the untransfected cells. In CML stem/progenitor cells obtained from patients with CML, the expression of PHLPP gene was suppressed in 10/10 (100 %) of CML. This higher expression was not associated to the counts of blasts of PB (P < 0.001). The transfection with Bcr-Abl siRNA or treatment with Abl kinase inhibitors increased the expression of PHLPP mRNA and protein, and decreased the counts of CFU-GEMM, CFU-GM and BFU-E. [Conclusions] Our results suggest that the Bcr- Abl suppressed the expression of PHLPP mRNA and protein, and the phosphorylation of Akt in CML cells to induce the proliferation of CML cells. Moreover, induction of PHLPP expression might regulate the proliferation of CML stem/progenitor cells.

[Background] Sugar derivatives whose oxygen atom in the hemiacetal ring is replaced by a carbon, nitrogen, sulfur atom, and etc., are celled as pseudo sugars. The synthesis and bioassay of these pseudo sugars are well investigated and are known as potential bioactive materials. Phospha sugar, which is one of pseudo sugars, having a phosphorus atom instead of the oxygen atom in the hemiacetal ring, is little known. The synthesis and bioassay of phospha sugars are not well studied in detail. We synthesized the 2, 3, 4-tribromo-3-methyl-1-phenyl phospholane 1-oxide (TMPP) and 2, 3-dibromo-3-methyl-1-phenyl phospholane 1-oxide (DMPP) by the nucleophilic substitution reactions, and found their anti-leukemic activities. [Purpose] The aims of the present study were to evaluate the inhibition of proliferation and induction of apoptosis in leukemia cell treated with TMPP or DMPP, and define the target molecules for TMPP in leukemia cells. [Methods] The cells used in this study were human leukemia cell lines, K562, U937, and YRK2 cells. For proliferation analysis, MTT assays were performed in leukemia cells treated with TMPP. For cell cycle analysis, flow cytometory analysis was performed in leukemia cells treated with TMPP or DMPP by PI staining. For analysis of mitotic regulatory proteins (p27, p21, Skp2, Cdc25B, Cyclin D1, Survivin, and Aurora kinase B), Western blotting was performed in leukemia cells treated with TMPP. [Results] In leukemia cell lines, DMPP and TMPP significantly inhibited the cell proliferation, and TMPP more strongly inhibited the cell proliferation than DMPP. 10 μM TMPP significantly induced G2/M phase arrest, and 25 μM TMPP induced apoptosis in leukemia cells. In leukemia cells, 10 μM TMPP reduced protein of Aurora kinase B, Survivin, Cyclin D1, Skp2 KIS, and FoxM1, while increased protein expression of p21and p27 by western blot analysis. Moreover, 25 μM TMPP activated caspase-3 and caspase-9, cleaved PARP, and reduced Bcl-2. [Conclusions] In this study, we report in the first time the possibility of phospha sugar derivatives as anti-leukemic agents in therapy for leukemias, and analysis of their characterizations. DMPP significantly inhibited the proliferation, and induced apoptosis of leukemia cells. These results demonstrated that the FoxM1, which is an essential transcription factor for cell growth and regulates expression of the mitotic regulators, is one of the targets for DMPP. Therefore, DMPP or TMPP has possibility as new agents for FoxM1 in leukemia therapy.

[Background] FoxM1, a member of the Fox transcription factor family, plays an important cell cycle regulator of both the transition from G1 to S phase and progression to mitosis. FoxM1 expression was also found to be up-regulated in some solid tumors (basal cell carcinomas, hepatocellular carcinoma, and primary breast cancer). These results suggested that FoxM1 plays a role in the oncogenesis of malignancies. However, it is unknown whether FoxM1 expression contributes to the development or progression of leukemia cells. Therefore, we investigated how FoxM1 regulated the cell cycle of leukemia cells and the expression analysis of the FoxM1 gene in patients with acute leukemias. [Methods] The cells used in this study were human acute leukemia cell lines, U937 and YRK2 cells. Primary acute myeloblastic (25 AML (4 M1, 11 M2, 6 M4, 4 M5)) cells were obtained from the peripheral blood. Human normal mononuclear cells (MNCs) were isolated from peripheral blood (PB) of healthy volunteers after obtaining informed consents. For analysis of proliferation and mitotic regulatory proteins (p27, p21, Skp2, Cdc25B, Cyclin D1, Survivin, Aurora kinase B, and KIS) in leukemia cells, MTT assays and western blot were performed in all cell lines, which untransfected or transfected with siRNA FoxM1, respectively. For cell cycle analysis, flow cytometory analysis was performed in leukemia cells untransfected or transfected with siRNAFoxM1 by PI staining. For analysis of FoxM1 mRNA, quantitative RT-PCR was performed in all cell lines and clinical samples. [Results] In all leukemia cell lines, the expression of FoxM1B mRNA were significantly higher than normal MNCs. When transfected with the siRNA FoxM1 in leukemia cells, suppression of FoxM1 caused a mean 71% (range 62 to 80%) reduction in S phase cells and a mean 4.4-fold (range 3.2 to 5.6-fold) increase in G2/M phase cells compared to controls. MTT assay demonstrated that the proliferation of the siRNA FoxM1 transfected cells was inhibited compared to the untransfected cells. Moreover, FoxM1 knockdown by siRNA in leukemia cells reduced protein and mRNA expression of Aurora kinase B, Survivin, Cyclin D1, Skp2 and Cdc25B, while increased protein expression of p21and p27. In the clinical samples obtained from patients with acute leukemias, the FoxM1B gene was overexpressed in 22/25 (88%). The relative folds of FoxM1B gene expression were for AML: 2.83 compared to normal MNCs. [Conclusions] In this study, we report in the first time that FoxM1 is overexpressed in myeloid leukemia cells. These results demonstrated that expression of FoxM1 is an essential transcription factor for growth of leukemia cells, and regulate expression of the mitotic regulators. Moreover, we showed that FoxM1 induced the expression of KIS protein. Therefore, FoxM1 might be one of moleculer targets of therapy for acute leukemias.

Rituximab has greatly improved the prognosis of B cell malignancies (BCM). However, several resistance mechanisms have been reported, including the inhibition of apoptosis, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) as well as modulation of CD20 antigen and increased complement-related cytotoxicity inhibition factor (CD55). The calicheamicin-conjugated anti-CD22 monoclonal antibody (mAb), CMC544, is one of the new promising agents, and effective on several types of BCM in vitro, especially when used in combination with rituximab. However, details regarding the cytotoxic effects of CMC544 and mechanisms triggering cell death, particularly when it is combined with rituximab, have not been elucidated. We studied cell cycle features of CMC544 on BCM used alone or in combination with rituximab, and analyzed quantitative alteration of target molecules such as CD20, CD22 and CD55.(Materials and Methods) The cell lines used in this study were CD22-positive Daudi and Raji cells, and CD22-negative Jurkat and NB4 cells. Cells obtained from 8 patients with BCM were also used. CMC544, unconjugated anti-CD22 mAb (G5/44), and free NAC-calicheamicin DMH were provided by Wyeth Pharmaceutical Co., Ltd. The effects of CMC544 were analyzed by incubating the cells at the concentrations of 0–100μg/ml for 0–96h, then by measuring cell count, cell viability, 3H-thymidine incorporation and cell cycle distribution on flow cytometry (FCM) as well as by video microscopic observation. The amounts of CD20, CD22 and CD55 antigens were analyzed by FCM, laser scanning microscope. The process of CMC544-induced cell death was assessed by Apocyto®. Three possible mechanisms of the combined effect of CMC544 and rituximab were investigated separately by direct effect of the mAb, CDC and ADCC. (Results) Analysis of the cell cycle distribution indicated that CD22-positive cells were temporally arrested at the G2/M phase after 6–12h incubation with CMC544, and the hypodiploid proportion increased after 24–72h. CD22-positive cells enlarged after 12–24h incubation with CMC544. Apoptotic morphological changes such as bleb formation and cell shrinkage were observed in 35–57% of the cells. These changes were not observed after incubation with G5/44. Apocyto® stain showed a continuous pattern from early to late apoptosis. Similar effects were observed in clinical samples that expressed CD22. The amounts of CD22 and CD55 were significantly reduced 3h after incubation with CMC544, while the CD20 expression was maintained 24h after incubation with CMC544. Incubation of the cells for 12–24h with CMC544 and then for 12hr with rituximab induced 1.2–2.1 times more anti-proliferation, apoptosis, CDC and ADCC than simultaneous incubation.(Conclusion) The effect of CMC544 was clearly observed as G2/M arrest following increase of the hypodiploid proportion in the cell cycle distribution, and this was a useful method to investigate the effect of CMC544. Combination of CMC544 and rituximab enhanced the cytotoxic effect, and sequential administration was more effective. The reduction of CD55 and continued expression of CD20 after the incubation with CMC544 supported the above observation. Further investigations are required to find the most effective treatment regimen to overcome drug resistance of B cell malignancies.

Background: The conserved Aurora family kinases, a family of mitotic serine/threonine kinases, have three members (Aurora-A, -B and -C) in mammalian cells. The Aurora kinases are involved in the regulation of cell cycle progression, and alterations in their expression have been shown to associate with cell malignant transformation. Aurora A localizes to the centrosomes during anaphase, and it is required for mitotic entry. Aurora B regulates the formation of a stable bipolar spindle-kinetochore attachment in mitosis. The function of Aurora-C in mammalian cells has not been studied extensively. In this study, we investigated that human leukemia cells expressed all 3 Aurora kinases at both protein and mRNA level, and the mechanisms of cell cycle regulation by knock down of Aurora C in leukemia cells. Methods: In this study, we used the 7 human leukemia cell lines, K562, NB4, HL60, U937, CEM, MOLT4, SUP-B15 cells. The expression levels of mRNA and proteins of Aurora kinases were evaluated by RT-PCR and western blot. The analysis of proliferation and cell cycle were performed by MTT assay and FCM, respectively. Results: The mRNA of Aurora-A and Aurora-B are highly expressed in human leukemia cell lines (K562, NB4, HL60, U937, CEM, MOLT4, SUP-B15 cells), while the mRNA of Aurora C is not only expressed highly in all cells. In contrast, an increase in the protein level of the 3 kinases was found in all cell lines. These observations suggested posttranscriptional mechanisms, which modulate the expression of Aurora C. In cell cycle analysis by flow cytometory, the knock down of Aurora C by siRNA induced G0/G1 arrest and apoptosis in leukemia cells, and increased the protein levels of p27Kip1 and decreased Skp2 by western blot. In MTT assay, it was revealed that the growth inhibition of leukemia cells transfected with siRNA Aurora C compared with leukemia cells untransfected with siRNA Aurora C. Moreover, We showed that Aurora C was associated with Survivin and directly bound to Survivin by immunoprecipitation and western blot. Conclusion: We found that human leukemia cells expressed all 3 members of the Aurora kinase family. These results suggest that the Aurora kinases may play a relevant role in leukemia cells. Among these Aurora kinases, Aurora C interacted with Survivin and prevented apoptosis of leukemia cells, and induced cell cycle progression. Our results showed that Aurora-C may serve as a key regulator in cell division and survival. These results suggest that the Aurora C kinase may play an important role in leukemia cells, and may represent a target for leukemia therapy.

The clinical result of has been significantly improved by arsenic trioxide (ATO) in acute promyelocytic leukemia (APL). ATO induces apoptosis of various cells and also bone marrow damage in relapsed or refractory patients who had frequently received anti-leukemia agents. Therefore, neutropenia persists over a longer period of time after ATO treatment than after retinoic acid treatment. The neutropenia might be associated with a high incidence of infection. On the other hand, salvarsan, an arsenic-containing compound, had been used for the treatment of syphilis and trypanosomiasis. However, ATO has not been analyzed with regard to its potential as an anti-microbial agent and anti-leukemic agent. We analyzed the in vitro anti-microbial effects of ATO, and studied the incidence and severity of infection among APL patients who were treated with ATO. (Methods) ATO discs were specially prepared for the disc diffusion method. Bacteria isolated from clinical samples were suspended in McFarland 0.5, and uniformly applied onto appropriate culture media with an ATO disc. After incubation in humidified air with 5%CO2 at 37°C for 24 hours, the bacterial growth-inhibitory zone was measured. In other experiments, bacteria and APL NB4 cells were co-cultured in 5%FCS-RPMI medium containing ATO (10−6–10−7M). The number of bacteria was counted after 24-hour incubation. (Patients) Thirty-eight patients with relapsed/refractory APL were treated with ATO (0.15mg/kg/day): 30 patients were treated with ATO alone, and 8 were treated with a combination of ATO and chemotherapy. Thirty-four cases achieved complete remission. The body temperature, duration of febrile neutropenia, neutrophil count, immunoglobulin level, focus of infection, and pharmacokinetics of ATO were studied. The incidence and kinds of viral infection were also analyzed. (Results) ATO significantly inhibited in vitro growth of 17 different bacteria isolated from clinical samples. The growth of E. coli, S. aureus (MSSA), H. influenzae, and St. pneumoniae among others was inhibited by the concentration of ATO that is clinically used. Fever with temperatures above 38°C was observed in 16 patients and the fever persisted for 4.4±2.2 (mean±SD) days. The duration of neutropenia of (Conclusion) ATO inhibit bacterial growth in vitro, and did not increase clinical bacterial infection while the duration of neutropenia in ATO-treated patients was relatively long. On the other hand, ATO increased the incidence of herpes zoster infection, especially among patients who concomitantly received ATO and chemotherapy.

[Background] Homeobox (Hox) genes are grouped together in 4 clusters, A to D. Recent studies has shown that the Hox proteins are important in the control of differentiation and proliferation in hematopoietic cells. It is reported that HoxA10 has been expressed in all types acute myeloid leukemias (except for APL) but not in acute lymphoid leukemias, implicating an important role as a regulator of myeloid progenitors. Moreover, overexpression of HoxA10 induses the proliferation of early progenitor cells and leads to the development of myeloid leukemias. However, we found that Bcr-Abl inhibitors increased the expression of HoxA10 gene in CML cells. In this study, we investigated the mechanism controlling HoxA10 in CML cells treated with Bcr-Abl inhibitors. [Methods] The cells used in this study were Ph1 positive CML cells, K562 and Meg01, and U937 cells for a Ph1 negative cell. We used AMN107 and BMS354825 for Bcr-Abl inhibitors, LY294002 for a PI3K inhibitor, PP2 for a Src kinase inhibitor, and SB203580 for a p38 MAP kinase inhibitor. For analysis of HoxA10 mRNA and protein, RT-PCR and western blot were performed in K562, Meg-01 and U937 cells, which untreated or treated with AMN107, BMS354825, LY294002, PP2, or SB203580 respectively. We then attempted to localize the intracellular locations of HoxA10 in K562 and Meg01, which untreated or treated with AMN107, BMS354825, or LY294002 by using conforcal fluorescence microscopy. Finally, for analysis of proliferation in K562, Meg-01 and U937 transfected with siRNA HoxA10, MTT assays were performed in untransfected or transfected K562, Meg-01 and U937 treated with or without AMN107, BMS354825, orLY294002. [Results] Both K562 and Meg01 cells expressed HoxA10 mRNA and protein at lower level compared to U937 cells. Interestingly, treatment with AMN107, BMS354825, or LY294002 increased the expression of HoxA10 mRNA and protein in both K562 and Meg01 cells. In contrast, treatment with PP2 or SB203580 did not affect the expression of HoxA10 mRNA and protein in both K562 and Meg01 cells. The fluorescence of HoxA10 was more strongly observed in the area corresponding to the cell’s cytoplasm than nucleus, and the treatment with AMN107, BMS354825, or LY294002 increased the fluorescence in nucleus of K562 and Meg01 cells in a time-dependent manner. In K562 and Meg01 cells transfected with the siRNA HoxA10, treatment with AMN107 or BMS354825 slightly inhibited the proliferation compared to K562 and Meg01 transfected with control siRNA. [Conclusions] In this study, we showed that Bcr-Abl inhibitors induced the expression of HoxA10, and HoxA10 was regulated by PI3K/P[Kappa[B pathway in CML cells. This finding indicates a new insight in the regulation of cell proliferation via the PI3K/PKB signal pathway in CML cells.

[Background] FoxM1, a member of the Fox transcription factor family, plays an important cell cycle regulator of both the transition from G1 to S phase and progression to mitosis. FoxM1 expression was also found to be up-regulated in some solid tumors (basal cell carcinomas, hepatocellular carcinoma, and primary breast cancer). These results suggested that FoxM1 plays a role in the oncogenesis of malignancies. However, it is unknown whether FoxM1 expression contributes to the development or progression of leukemia cells. Therefore, we investigated whether and how FoxM1 regulated the cell cycle of leukemia cells. [Methods] The cells used in this study were human leukemia cell lines, K562, HL60, U937 cells. For analysis of FoxM1 mRNA, RT-PCR was performed in all cell lines. For analysis of proliferation and mitotic regulatory proteins (p27, p21, Skp2, Cdc25B, Cyclin D1, Survivin, and Aurora kinase B) in leukemia cells, MTT assays and western blot were performed in all cell lines untransfected or transfected with siRNA FoxM1, respectively. For cell cycle analysis, flow cytometory analysis was performed in leukemia cells untransfected or transfected with siRNAFoxM1 by PI staining. [Results] In all leukemia cell lines, the expression of FoxM1B mRNA were significantly higher than normal MNCs. In K562, HL60, and U937 cells transfected with the siRNA FoxM1, suppression of FoxM1 caused a mean 71% (range 62 to 80%) reduction in S phase cells and a mean 4.4-fold (range 3.2 to 5.6-fold) increase in G2/M phase cells compared to untransfected cells. MTT assay demonstrated that the proliferation of the siRNA FoxM1 transfected cells was inhibited compared to the untransfected cells at 2, 3, 4, or 5 days after siRNA FoxM1 transfection. FoxM1 has been reported to regulate transcription of essential mitotic regulatory genes. We showed that FoxM1 knockdown by siRNA in leukemia cells reduced protein and mRNA expression of Aurora kinase B, Survivin, Cyclin D1, Skp2 and Cdc25B, while increased protein expression of p21and p27 in RT-PCR and western blot analysis. [Conclusions] In this study, we report in the first time that FoxM1 is overexpressed in myeloid leukemia cells. These results demonstrated that expression of FoxM1 is an essential transcription factor for growth of leukemia cells, and regulate expression of the mitotic regulators, Cdc25B, Cyclin D1, Survivin, Aurora kinase B, and p21. Moreover, we showed that FoxM1 regulated the expression of Skp2 protein, which is known to promote degradation of the cell cycle regulator p27. Our study found that inhibition of FoxM1 expression in leukemia cells suppressed their growth in vitro. Therefore, FoxM1 might be a new potential target of therapy for leukemias. We will have further study whether the level of FoxM1 expression in leukemia cells is correlated with patient survival or sensitivity for chemotherapy.

[Background] The proto-oncogene Akt/PKB is activated in many human cancers including leukemias, and regulates the cell survival and apoptosis. Akt/PKB is activated by growth factors or the phosphatidylinositol-3,4,5-triphosphate via PI3K, phosphorylates many substrates for cell survival or proliferation. The tumor suppressor PTEN prevents Akt/PKB phosphorylation and activation. On the other hand, the PH domain leucine-rich repeat protein phosphatase (PHLPP) dephosphorylates Akt/PKB, induces apoptosis, and suppresses tumor growth. It has been reported that the expression levels of PHLPP are significantly reduced in several colon cancer and glioblastoma cell lines, and Akt/PKB phosphorylation is elevated. Therefore, in these cell lines, the reduction of PHLPP causes to promote tumor growth. In this study, we have investigated the expression and function of PHLPP in leukemia cells. [Methods] The cells used in this study were human leukemia cell lines, K562, HL60, U937, CEM, and MOLT4 cells. Primary acute lymphoblastic leukemia (6ALL (6 L2)), myelodysplastic syndromes (8 MDS (8 RAEB)), and acute myeloblastic (12 AML (3 M1, 4 M2, 2 M3, 2 M4, 1 M5)) cells were obtained from the peripheral blood. Human normal mononuclear cells (MNCs) were isolated from peripheral blood (PB) of healthy volunteers after obtaining informed consents. For analysis of PHLPP mRNA, RQ-PCR was performed in all cell lines and clinical samples before and after chemotherapy. For analysis of proliferation in all cell lines, MTT assays and western blot were performed in all cell lines untransfected or transfected with siRNA pHLPP. [Results] In all cell lines and clinical samples obtained from patients with leukemia, the expression of PHLPP mRNA were significantly higher than normal MNCs. In K562, HL60, U937, CEM and MOLT4 cells transfected with the siRNA PHLPP, it is shown that the proliferation of these cells was stimulated and the phosphorylation state of Akt was markedly increased compared to the untransfected cells. The mean PHLPP gene expression was for AML: 3.57, MDS: 2.18, and ALL 3.14 relative to normal MNCs. Mean PHLPP expression was significantly higher in AML, MDS and ALL compared to normal MNCs (P < 0.01). Moreover, when CR status after chemotherapy, mean PHLPP expression levels were significantly reduced compared to unCR status after chemotherapy in MNCs from PB of patients with leukemia. [Conclusions] In this study, we showed in the first time that the PHLPP expression levels were high compared to normal MNCs in leukemia cells. Quantitive analysis of PHLPP gene expression in PB appeared to be a useful tool in discriminating abnormal levels in AML, MDS and ALL patients. Moreover, it is serves as an ideal target for MRD monitoring in PB. However, it is unclear why PHLPP, which is reported that promotes apoptosis and suppresses tumor growth, is at high expression level in leukemia cells.

Purpose: The protein p27 is an important regulator of cell cycle. An increase in p27 causes proliferation of cells, while a decrease in p27 induces quiescence of cells. p27 is regulated by transcriptional, translational and proteolytic mechanisms. Among them, an importnant mechanism in the regulation of p27 is proteolysis. Kinase interacting with stathmin, KIS, is a serine / threonine kinase, and regulates cell cycle progression through the phosphorylation of p27 on serine 10. The S10 phosphorylation on p27 plays an important role in p27 degradation. KIS that phosphorylates p27 on S10 and its role in the regulation of cell cycle progression have not been defined in leukemia cells. In this study, we investigated the role of KIS in leukemia cells. Materials and Methods: We examined the biological significance of KIS expression in K562, NB4, U937, CEM, MOLT4, and SUP-B15 leukemia cells and relationship with the G1 regulaters, such as p27. Moreover, we generated the lentivirus vector inserted with the dsDNA of KIS small interfering RNA (siRNA), and effects of down-regulation of KIS by siRNA transfection were investigated in leukemia cells. Results: RT-PCR and western blot analysis showed high KIS expression in all leukemia cells. The p27 phosphorylation on S10 was significantly lower in the leukemia cells transduced with KIS siRNA and depletion of KIS enhanced growth arrest. The down-regulation of KIS induced G1 arrest in cell cycle, but not apoptosis. In cell cycle analysis, control leukemia cells showed 42.3 ± 1.8 %, but leukemia cells transfected with KIS siRNA showed 67,1 ± 2.1 % in G1 fraction. Moreover, these cells significantly showed small population in S ansd G2 fractions compared compared with controls. Conclusion: These findings suggest KIS expression promotes cell cycle progression in leukemia cells. Depletion of KIS using siRNA in leukemia cells induced cell cycle arrest in G1 phase compared with control cells. In this study, we showed that KIS might be the target for the molecular therapy.

Cyclooxygenase-2 (COX-2) is reported to be an important cellular target for therapy in malignancies. The growth inhibitory effects of COX-2 inhibitors on malignancies have been demonstrated to be through not only COX-2 dependent, but also independent mechanisms. In this study, we showed that etodolac, COX-2 inhibitor, induced apoptosis via COX-2 independent pathway, and investigated the molecular details of etodolac-induced apoptosis in Burkitt’s lymphoma cells. In Daudi and Raji Burkitt’s lymphoma cell lines, which expressed no COX-2 enzyme, etodolac more strongly induced apoptosis compared to meloxicam. Moreover, Etodolac did not induce apoptosis to normal B lymphocytes. For the pathway of etodolac-induced apoptosis, reduction of anti-apoptotic bcl-2 mRNA and Bcl-2 protein, activation of Caspase-9 and -3, down-regulation of caspase inhibitors, c-IAP-1 and Survivin were involved. Moreover, EBER-1 and -2 expression in EBV positive Daudi and Raji cells were reduced to result in down-regulation of Bcl-2 by treatment with etodolac. It has been reported that etodolac has stereoisomers, R- and S- etodolac. We found that racemate of etodolac more strongly induced apoptosis in Daudi and Raji cells compared to R- or S- etodolac. In conclusion, our findings indicated etodolac inhibited EBERs expression and induced apoptosis via a Bcl-2-regulated pathway. Moreover, racemate of etodolac more effectively induced apoptosis than R- and/or S- etodolac. Therefore, these activities of etodolac potentially extend to the treatment of patients with Burkitt’s lymphoma resistant to chemotherapy.

Background: The therapy with ATO induced high complete remission and maintained for long survival for patients with relapsed or refractory APL. While the clinical effect of ATO against APL was confirmed, its pharmacokinetics has yet to be clarified. In most reports on pharmacokinetics of ATO, the arsenic concentrations were measured as total arsenic. We investigated the pharmacokinetics of arsenic species in Japanese patients with relapsed or refractory APL treated with ATO. Patients and Methods: In the prospective study, from 12 patients with APL treated with ATO, the blood and urine for the pharmacokinetic data were collected and subsequently stored frozen until analysis. ATO (0.15 mg/kg) was intravenously administered once daily over 2 hours to until bone marrow remission to a maximum of 60 days. The plasma and urine were collected on day 1 and after 1, 2 and 4 weeks. Inorganic arsenic (AsIII and AsV) and the major metabolites monomethylarsonic acid (MAAV) and dimethylarsinic acid (DMAAV) in plasma and urine were quantified by HPLC/ICP-MS. Results: Ten of 12 patients (83%) achieved complete remission (CR). Six of ten (60%) who achieved CR were negative in the post-treatment RT-PCR test. For two patients the blood and urine were collected also during consolidation. The plasma concentrations of inorganic arsenic on day 1 reached the Cmax (mean 22.6±11.4 ng/mL) immediately after completion of administration followed by a biphasic elimination while the appearance of methylated metabolites in the blood was delayed. During the repeated administration, the plasma concentrations of inorganic arsenic reached the steady-state. The Cmax of inorganic arsenic on week 4 was similar (mean 23.2±10.2 ng/mL) but the elimination was delayed. As a result, the AUC increased about 2-fold (from mean 211.8±55.1 to 474.8±192.6 ng/mL), and the clearance declined (from 0.7±0.2 to 0.4±0.1 L/kg/h) but no marked change was observed in volume of distribution. In contrast, the MAAV and DMAAV concentrations increased in relation to increased administration frequency fold (from mean 3.1±1.6, 5.4±2.9 to 10.9±4.7, 21.4±12.3 ng/mL). The plasma concentrations of arsenobetaine, an organic arsenic compound derived from seafood, remained almost constant (about 2 mg/mL) during the study period. The urinary excretion rates of AsIII and AsV remained almost constant after week 1, suggesting that the steady-state was attained. In contrast, a tendency to increase with administration frequency was observed in the excretion rates of MAAV and DMAAV after week 4 (from mean 17.4±11.2, 19.4±8.5 to 19.6±10.0, 21.1±9.5 %). The total arsenic excretion rate remained at ~60% of dose after week 1. Conclusion: ATO is metabolized when administered intravenously to APL patients and methylated metabolites were promptly eliminated from the blood and excreted into urine after completion of administration, indicating no measurable accumulation of ATO in the blood.

Cyclooxygenase-2 (COX-2) is reported to regulate apoptosis and to be an important cellular target for therapy. In this study, we demonstrated that etodolac, a COX-2 inhibitor, inhibited proliferation and induced apoptosis in myeloma cell lines (RPMI 8226 and MC/CAR cells), expressing the COX-2 enzyme. In both cell lines, etodolac more strongly induced apoptosis compared with thalidomide or meloxicam. Etodolac induced down-regulation of bcl-2 protein and mRNA, activation of caspase-9, -7 and -3, down-regulation of caspase inhibitors, cIAP-1 and survivin, and loss of mitochondrial membrane potential in a dose-dependent manner. In addition, our data demonstrated that when myeloma cells were coincubated with 50 mM etodolac on bone marrow stromal cells (BMSC), myeloma cell adhesion to BMSC was significantly inhibited compared with thalidomide or meloxicam coincubation, and the adhesion molecules VLA-4, LFA-1 (CD11a), CXCX4, and CD44 were suppressed on myeloma cells treated with etodolac. Moreover, we found that 100 mM R-etodolac, S-etodolac, and the combination of R- and S-etodolac, which are the stereoisomers of etodolac, slightly inhibited the proliferation of myeloma cells, while 50 to 100 mM etodolac significantly inhibited the proliferation of myeloma cells. In conclusion, our findings indicate that etodolac induced apoptosis via a bcl-2 dependent pathway, suppressed the expression of adhesion molecules, and inhibited myeloma cell adhesion to BMSC compared with thalidomide or meloxicam. Thus, the activities of etodolac potentially extend to the treatment of patients with myeloma resistant to standard chemotherapy, including thalidomide.

Several studies including ours have suggested that lack of CD56 expression in multiple myeloma (MM) defines a unique patient subset with poorer prognosis. However, the mechanism underlying this aggressive behavior of CD56− MM has not been well elucidated. In this study, we sorted out both CD56− and CD56+ fractions from MM cell lines or patients with MM, and investigated their different responsiveness to interleukin-6 (IL-6) or insulin like growth factor-I (IGF-I), and tried to clarify the course of action in cell cycle distribution. After stained with PE-CD56, CD56− and CD56+ fractions in KMS-21-BM and U-266 cell lines were isolated by the cell sorter, and cultured separately either in the presence or absence of IL-6 (2 ng/ml and 10 ng/ml, respectively). Although CD56− cells in both KMS-21-BM and U-266 cell lines responded significantly to IL-6 (P=0.001 and 0.009, respectively), CD56+ cells did not. Ki-67+ cells in CD56− KMS-21-BM cells, that were significantly fewer than that in CD56+ ones (P=0.0003), increased significantly upon 24-hour incubation with IL-6 (P