Kenji Tsunekawa

Transcriptional Repression of Cdc25B by IER5 Inhibits the Proliferation of Leukemic Progenitor Cells through NF-YB and p300 in Acute Myeloid Leukemia

The immediately-early response gene 5 (IER5) has been reported to be induced by γ-ray irradiation and to play a role in the induction of cell death caused by radiation. We previously identified IER5 as one of the 2,3,4-tribromo-3-methyl-1-phenylphospholane 1-oxide (TMPP)-induced transcriptional responses in AML cells, using microarrays that encompassed the entire human genome. However, the biochemical pathway and mechanisms of IER5 function in regulation of the cell cycle remain unclear. In this study, we investigated the involvement of IER5 in the cell cycle and in cell proliferation of acute myeloid leukemia (AML) cells. We found that the over-expression of IER5 in AML cell lines and in AML-derived ALDHhi (High Aldehyde Dehydrogenase activity)/CD34+ cells inhibited their proliferation compared to control cells, through induction of G2/M cell cycle arrest and a decrease in Cdc25B expression. Moreover, the over-expression of IER5 reduced colony formation of AML-derived ALDHhi/CD34+ cells due to a decrease in Cdc25B expression. In addition, over-expression of Cdc25B restored TMPP inhibitory effects on colony formation in IER5-suppressed AML-derived ALDHhi/CD34+ cells. Furthermore, the IER5 reduced Cdc25B mRNA expression through direct binding to Cdc25B promoter and mediated its transcriptional attenuation through NF-YB and p300 transcriptinal factors. In summary, we found that transcriptional repression mediated by IER5 regulates Cdc25B expression levels via the release of NF-YB and p300 in AML-derived ALDHhi/CD34+ cells, resulting in inhibition of AML progenitor cell proliferation through modulation of cell cycle. Thus, the induction of IER5 expression represents an attractive target for AML therapy.

Synthesis of 5-deoxy-3-O-methyl-5-C-(phenylphosphinyl)-l-idopyranose

Synthese a partir de didesoxy-5,6 O-isopropylidene-1,2 O-methyl-3 nitro-6 α-D-xylo-hexeno-5furanose et de phenylphosphine

Research on Phospha Sugar Analogues to Develop Novel Multiple Type Molecular Targeted Antitumor Drugs Against Various Types of Tumor Cells

Abstract The synthesis and antitumor activity evaluation of new branched phospha sugars, especially deoxybromophospha sugar derivatives or bromophospholanes of 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide (DBMPP: 3) and 2,3,4-tribromo-3-methyl-1- phenylphospholane 1-oxide (TBMPP: 4), against various types of leukemia cell lines as well as the results of the mechanistic studies for characterizing and developing the novel multiple type molecular targeted antitumor agents are reported in this paper. DBMPP and TBMPP were prepared from 1-phenyl-3-methyl-2-phospholene 1-oxide (1). The isomer mixture of phospha sugars prepared were evaluated as novel antitumor agents by MTT in vitro method. DBMPP and TBMPP were characterized by flow cytometry and Western blot analysis and were revealed to be potential antitumor agents against leukemia cell lines of K562 (one type of leukemia cell lines of CML) and U937 (one type of leukemia cell lines of AML) as well as against the various types of leukemia cell lines and also against solid tumor cell lines of stomach, skin, and lung cancers by MTT evaluation and observation by a handstand phase-contrast microscope. The results of the flow cytometry indicated that the mechanism of apoptosis induced by phospha sugar derivatives not only to tumor cells of leukemia cell lines of U937 but also to tumor cells of various kinds of leukemia cell lines selectively to decrease the tumor cell viability of various kinds of leukemia cell lines. The Western blot analyses for phospha sugar DBMPP against U937 leukemia cell lines showed that the phospha sugar affected on the expressions of the factors of cell cycles in the manners of suppressing the expression of the accelerator factors of cell cycles of tumor cells and enhancing the expression of suppressor factors of cell cycles of tumor cells by the medications of phospha sugars. TBMPP enhanced the expression of IER5 and then suppressed the expression of Cdc25B, which is the common factor to accelerate the cell cycles of various kinds of tumor cells. Therefore, suppression of the expression of Cdc25B by TBMPP implies that the branched deoxybromophospha sugar derivatives might be novel and potential multiple type molecular targeted antitumor agents against various kinds of tumor cell lines. GRAPHICAL ABSTRACT

Preparation of Phospha Sugar Analogues and Their Evaluation as Novel Molecular Targeting Anticancer Agents

Abstract Phospha sugars were prepared by a novel synthetic route starting from phosphorus heterocyclic compounds, 2-phospholenes. The anhydro- and deoxy-phospha sugar derivatives have been revealed to have potential anticancer activities against human leukemia of K562 and U937 cell lines. In this article, deoxybromophospha sugars with different numbers of bromo substituents were prepared, and their anticancer activities were evaluated by MTT method. The order of the activities depending on the number of bromo substituent was first revealed, and trideoxytribromotetrofuranose type phospha sugar [2,3,4-tribromo-3-methyl-1-phenylphospholane 1-oxide (4: TBMPPAO)] was the most active among these phospha sugars prepared. Diasteromers of dideoxydibromotetrofuranose-type phospha sugar [2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide (2: DBMPPAO)] were separated into four components, and the structure as well as the character of each component was assigned by spectral and chromatographic data as well as by MTT method.The deoxybromophospha sugars have higher antileukemia activity than Gleevec against U937 cells.

Preparation and Evaluation of Novel Sugar Dendritic Gd-DTPA Complexes for MRI Contrast Agents and Phospha Sugars for Anti-Tumour Agents

Novel Sugar Dendritic Gd(III)-DTPA complexes for MRI Contrast Agents (CAs) were prepared and evaluated by in vitro and in vivo methods. The sugar dendritic MRI contrast agents had a good blood vessel pool character and drew blood vessels and liver cancers remarkably clearer and longer time enough than the clinically being used Gd(III)-DTPA complex (Magnevist). Phospha sugar derivatives or phosphorus heterocyclic derivatives provided by functional groups such as epoxide, bromide, etc., were prepared and evaluated by the MTT in vitro method. These phospha sugar derivatives showed excellent anti-proliferative effects of leukemia cell lines, e.g., K562 and U937, as well as solid cancer cells in fashions of (i) higher activity, (ii) wider spectra, and (iii) higher selectivity and specificity than Imatinib mesylate (Gleevec), which is one of the most frequently used chemotherapeutical molecular targeting anti-tumour agent.