Biological significance of myeloperoxidase (MPO) on green tea component, (−)-epigallocatechin-3-gallate (EGCG)-induced apoptosis: its therapeutic potential for myeloid leukemia

The therapeutic approach to acute myeloid leukemia (AML) is usually chemotherapy, but severe side effects and complications induced by the anticancer drugs are sometimes fatal and are major problems in the clinical setting. Recently, more specifically targeted agents have been developed for the treatment of AML; however, most candidate agents for targeted therapy have yet to be translated into clinical application. Natural compounds appear to be safer than the current chemotherapeutic agents. Recently, it has been reported that reactive oxygen species (ROS) produced by natural compounds such as (−)-epigallocatechin-3-gallate (EGCG) induce apoptosis in myeloid leukemic cells. EGCG markedly induced apoptosis of myeloperoxidase (MPO)-positive myeloid leukemic cells. Treatment with EGCG caused a significant ROS production in MPO-positive leukemic cells. ROS are now thought of as signaling molecules in response to various extracellular stimuli. On the other hand, ROS may be the direct mediator of EGCG-induced apoptosis in myeloid leukemic cells. In particular, highly toxic ROS such as hydroxyl radical (·OH) generated via the H₂O₂/MPO halide system may directly mediate oxidative stress-induced apoptosis in myeloid leukemic cells.     

New tubulin polymerization inhibitor derived from thalidomide: implications for anti-myeloma therapy

Despite the conventional and high-dose chemotherapy with hematopoietic stem cell transplantation, multiple myeloma eventually relapses, resulting in an incurable hematological malignancy. Therefore, novel therapeutic approaches in clinical settings are desired. Recently, thalidomide was introduced for the treatment of myeloma, and many clinical trials have since confirmed its efficacy in patients with relapsed/refractory or newly diagnosed multiple myeloma. Multiple mechanisms have been proposed to explain thalidomide's anti-myeloma activity. However, the precise mechanism underlying this activity remains unclear, because thalidomide rapidly undergoes spontaneous, nonenzymatic, hydrolytic cleavage to numerous metabolites in vivo. To elucidate the exact anti-myeloma mechanism of thalidomide in vivo, we have performed structural development studies of thalidomide, and obtained various analogs with specific molecular properties. Among these derivatives, we found that a new thalidomide analog, 2-(2,6-diisopropylphenyl)-5-hydroxy-1H-isoindole-1,3-dione (5HPP-33), has the most potent anti-myeloma effect with tubulin polymerization inhibiting activity. 5HPP-33 directly inhibited the growth and survival of various myeloma cells in a dose-dependent manner with IC(50) of 1-10 microM. In contrast, thalidomide itself did not inhibit RPMI8226 cell growth. A tubulin polymerization assay using microtubule protein from porcine brain revealed that 5HPP-33 had potent tubulin polymerization inhibiting activity with IC(50) of 8.1 microM, comparable to that of rhizoxin, a known tubulin polymerization inhibitor. Moreover, its activity was more potent than that of a known thalidomide metabolite, 5-hydroxythalidomide. Our data suggest that 5HPP-33 is a promising candidate as a therapeutic agent for multiple myeloma. In addition, the results suggest that thalidomide's tubulin polymerization inhibiting activity might be the mechanism underlying the induction of apoptosis in myeloma cells.     

Intracellular β2-adrenergic receptor signaling specificity in mouse skeletal muscle in response to single-dose β2-agonist clenbuterol treatment and acute exercise

The aim of this study was to clarify the intracellular β₂-adrenergic receptor signaling specificity in mouse slow-twitch soleus and fast-twitch tibialis anterior (TA) muscles, resulting from single-dose β₂-agonist clenbuterol treatment and acute exercise. At 1, 4, and 24 h after single-dose treatment with clenbuterol or after acute running exercise, the soleus and TA muscles were isolated and subjected to analysis. The phosphorylation of p38 mitogen-activated protein kinase (MAPK) increased after single-dose clenbuterol treatment and acute exercise in the soleus muscle but not in the TA muscle. Although there was no change in the phosphorylation of Akt after acute exercise in either muscle, phosphorylation of Akt in the soleus muscle increased after single-dose clenbuterol treatment, whereas that in the TA muscle remained unchanged. These results suggest that p38 MAPK and Akt pathways play a functional role in the adaptation to clenbuterol treatment and exercise, particularly in slow-twitch muscles.     

Incorporation of gantry angle correction for 3D dose prediction in intensity-modulated radiation therapy

Pretreatment dose verification with beam-by-beam analysis for intensity-modulated radiation therapy (IMRT) is commonly performed with a gantry angle of 0° using a 2D diode detector array. Any changes in multileaf collimator (MLC) position between the actual treatment gantry angle and 0° may result in deviations from the planned dose. We evaluated the effects of MLC positioning errors between the actual treatment gantry angles and nominal gantry angles. A gantry angle correction (GAC) factor was generated by performing a non-gap test at various gantry angles using an electronic portal imaging device (EPID). To convert pixel intensity to dose at the MLC abutment positions, a non-gap test was performed using an EPID and a film at 0° gantry angle. We then assessed the correlations between pixel intensities and doses. Beam-by-beam analyses for 15 prostate IMRT cases as patient-specific quality assurance were performed with a 2D diode detector array at 0° gantry angle to determine the relative dose error for each beam. The resulting relative dose error with or without GAC was added back to the original dose grid for each beam. We compared the predicted dose distributions with or without GAC for film measurements to validate GAC effects. A gamma pass rate with a tolerance of 2%/2 mm was used to evaluate these dose distributions. The gamma pass rate with GAC was higher than that without GAC (P = 0.01). The predicted dose distribution improved with GAC, although the dosimetric effect to a patient was minimal.     

A new disulfide-linked dimer of a single-chain antibody fragment against human CD47 induces apoptosis in lymphoid malignant cells via the hypoxia inducible factor-1α pathway

CD47 belongs to the immunoglobulin superfamily and is associated with β-integrins. Recently it was reported that CD47 ligation rapidly induces apoptosis in B-chronic lymphocytic leukemia (CLL) cells. Chronic lymphocytic leukemia is still an incurable hematological malignancy even with the novel therapeutic agents; therefore, new and effective agents for the treatment of CLL in clinical settings are urgently needed. We generated a murine monoclonal antibody against an extracellular domain of human CD47 (designated MABL). Subsequently, we created a disulfide-stabilized dimer of a single-chain antibody fragment of MABL (S-S diabody) to get rid of the adverse effect of MABL such as hemagglutination. In this study, we analyzed the effects of this new antibody on cellular proliferation, and the molecular mechanism of CD47-mediated apoptosis in human lymphoid malignant cells. Treatment with S-S diabody alone induced apoptosis of CD47-positive primary B-CLL and leukemic cells (MOLT-4 and JOK-1). In addition, administration of S-S diabody significantly prolonged the survival of severe combined immunodeficiency (SCID) mice inoculated with JOK-1 cells. In gene expression profiling of the S-S diabody-treated MOLT-4 cells, hypoxia inducible factor (HIF)-1α downstream genes (RTP801 and BNIP3) were upregulated, and the mRNA expression levels of HIF-1α, RTP801 and BNIP3 were increased. Knockdown of HIF-1α by siRNA repressed S-S diabody-induced apoptosis in MOLT4 cells. In conclusion, CD47 will be a molecular target for the treatment of lymphoid malignancies, and S-S diabody might have potential as a novel therapeutic agent for B-CLL.     

Synovial sarcoma arising from the pleura: a case report with ultrastructural and immunohistological studies

Synovial sarcoma commonly occurs in the para-articular regions of the extremities, and rarely in the pleura. We report a 46-year-old woman with primary synovial sarcoma of the pleura. She was admitted with a complaint of left-sided chest pain and exertional dyspnea. She had previously undergone two operations for pleural neoplasm, at the ages of 33 and 36 years. A computed tomography scan revealed an expanded mass in the left thoracic cavity, involving the surrounding tissue. Macroscopic findings demonstrated a 25 x 25 x 15-cm grayish-white mass with hemorrhage beneath the pleura. Both epithelial and spindle cells were observed microscopically. Ultrastructural microscopy of the epithelioid cells demonstrated short, blunt microvilli on the luminal surface, and desmosomes between the neoplastic cells. Immunohistochemically, the tumor cells of the epithelial component were positive for embryonal membrane antigen (EMA), carcinoembryonic antigen (CEA), human mesothelial cells (HBME)-1, and cytokeratin, and the spindle cells were positive for vimentin. These findings led us to a diagnosis of primary synovial sarcoma of the pleura. She had no evidence of recurrence or metastasis after the third operation.     

Features of vascular adverse events in Japanese patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors: a retrospective study of the CML Cooperative Study Group database

This study investigated the incidence rate and features of vascular adverse events (VAEs) in Japanese patients with chronic myeloid leukemia (CML) who were treated with tyrosine kinase inhibitors (TKIs). The analysis included 369 CML patients in the chronic or accelerated phases, selected from the CML Cooperative Study Group database; 25 events in 23 (6.2%) of these patients were VAEs. At the time of VAE incidence, nine patients were on treatment with imatinib, 12 with nilotinib, three with dasatinib, and one with bosutinib. VAE incidence comprised 13 cases of ischemic heart disease (IHD), eight of cerebral infarction (CI), and four of peripheral arterial occlusive disease (PAOD). IHD incidence rate in the study population was higher than that in the age-matched general population, particularly in nilotinib-treated patients, while CI incidence rate was almost equivalent. Compared with the Suita score, the SCORE chart and the Framingham score risk assessment tools detected more patients with high or very high risk of VAEs. In conclusion, incidence of IHD requires closer monitoring in nilotinib-treated patients. More detailed investigations for determining the most useful tool to predict VAE incidence and long-term analysis of therapy-related VAE cases are needed for improving safety during TKI therapy.