Development and pharmacologic characterization of deoxybromophospha sugar derivatives with antileukemic activity.

Here, we synthesized two phospha sugar derivatives, 2,3,4-tribromo-3-methyl-1-phenylphospholane 1-oxide (TMPP) and 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide (DMPP) by reacting 3-methyl-1-phenyl-2-phospholene 1-oxide with bromine, and investigated their potential as antileukemic agents in cell lines. Both agents showed inhibitory effects on leukemia cell proliferation, with mean IC(50) values of 6.25 micromol/L for TMPP and 23.7 micromol/L for DMPP, indicating that inhibition appeared to be dependent on the number of bromine atoms in the structure. Further, TMPP at 10 micromol/L and DMPP at 20 micromol/L induced G2/M cell cycle block in leukemia cells, and TMPP at 20 micromol/L induced apoptosis in these cells. TMPP treatment effected a reduction in both cell cycle progression signals (FoxM1, KIS, Cdc25B, Cyclin D1, Cyclin A, and Aurora-B) and tumor cell survival (p27(Kip1) and p21(Cip1)), as well as induced the activation of caspase-3 and -9. Further, treatment with TMPP significantly reduced the viability of AML specimens derived from AML patients, but only slightly reduced the viability of normal ALDH(hi) progenitor cells. We also observed that FoxM1 mRNA was overexpressed in AML cells, and treatment with TMPP reduced FoxM1 mRNA expression in AML cells. Here, we report on the synthesis of TMPP and DMPP and demonstrate that these agents hinder proliferation of leukemia cells by FoxM1 suppression, which leads to G2/M cell cycle block and subsequent caspase-3-dependent apoptosis in acute leukemia cells. These agents may facilitate the development of new strategies in targeted antileukemic therapy.

Preparation and characterization of novel 4-bromo-3,4-dimethyl-1-phenyl-2-phospholene 1-oxide and the analogous phosphorus heterocycles or phospha sugars.

4-Bromo-3,4-dimethyl-1-phenyl-2-phospholene 1-oxide (3c) was first synthesized from 3,4-dimethyl-1-phenyl-2-phospholene 1-oxide (2c) by a bromo-radical substitution reaction occurred at C-4 position by N-bromosuccinimide and 2,2'-azobisisobutyronitrile. The novel phospha sugar analogue 3c exerted high anti-proliferative effect on U937 cells evaluated by MTT in vitro methods and was much more efficient than that of Gleevec, which is known as a molecule targeting chemotherapeutical agent. The substitution of 2-phospholenes at C-3 and C-4 position with methyl groups as well as 4-bromo substituent suggests a good anti-proliferative effect.

Synthesis, in vitro and in vivo studies of Gd-DTPA-XDA-D1-Glc(OH) complex as a new potential MRI contrast agent.

A new type of dendritic molecules Gd-DTPA-XDA-D1-Glc(OH), which work as a functionalized ligand coordinating gadolinium(III) ion at the center of their frameworks with two glucose moieties on the molecular surfaces, were readily synthesized with high yield. The structures were established by IR, (1)H, (13)C NMR, and mass spectral studies. Its bio-distribution patterns were evaluated on rats.

Synthesis and in vitro evaluation of 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide for potential anti-proliferative effects.

A novel phospha sugar analogue, 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide (DBMPP), was prepared from 1-phenyl-3-methyl-2- phospholene 1-oxide and evaluated by in vitro MTT method forleukemia cells and microscopic observations forsolid tumor cells, e.g., stomach cancer cells. The evaluation revealed clearly that the synthesized phospha sugar analogue DBMPP has competent potentials and excellent anti-cancer activities that killed selectively and specifically the leukemia cells of cell lines of K562 and U937 but did not give any damages on healthy leukocyte. Moreover it was revealed that DBMPP killed solid cancer cells such as stomach cancer cells and melanoma of cell lines of MKN45 and G361. Therefore, DBMPP should exert anti-proliferative effects for different kinds of tumor cells based on the in vitro evaluations. The cell cycle analyses by flow cytometry for K562 and U937 cells clearly demonstrated that the mechanism of the anti-proliferative effect on the human tumor cells is apoptosis induced by DBMPP.

Evaluation of energy transfer in perylene-cored anthracene dendrimers.

Quantitative evaluation of Förster-type fluorescence resonance energy transfer (FRET) was undertaken by statistical investigations on perylene-cored anthracene dendrimers.

Synthesis and structural analyses of 3-acetamido-1,4-di-O-acetyl-2,3,5-trideoxy-5-C-(isopropylphosphinyl)-D-erythro-pentopyranoses.

1H NMR spectroscopy of phosphorus containing hetero sugars (phospha sugars), revealed the alpha and beta configurations and chair conformations for 3-acetamido-1,4-di-O-acetyl-2,3,5-trideoxy-5-C-(isopropylphosphinyl)-alpha- and beta-D-erythro-pentopyranoses. The conformation of the title compounds was determined by 1H NMR as 1C4 in CDCl3 and the conformation was in accord with that in solid state determined by X-ray crystallographic analysis.

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 ALDH(hi) (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 ALDH(hi)/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 ALDH(hi)/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 ALDH(hi)/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.

Crystal structure of achiral nonapeptide Boc-(Aib-DeltaZPhe)4-Aib-OMe at atomic resolution: evidence for a 3(10)-helix.

An x-ray crystallographic analysis was carried out for Boc-(Aib-DeltaZPhe)4-Aib-OMe (1: Boc = t-butoxycarbonyl; Aib = alpha-aminoisobutyric acid; DeltaZPhe = Z-alpha,beta-didehydrophenylalanine) to provide the precise conformational parameters of the octapeptide segment -(Aib-DeltaZPhe)4-. Peptide 1 adopted a typical 3(10)-helical conformation characterized by = +/-55.8 degrees (50 degrees -65 degrees), = +/-26.7 degrees (15 degrees -45 degrees), and = +/-179.5 degrees (168 degrees -188 degrees) for the average values of the -(Aib-DeltaZPhe)4- segment (the range of the eight values). The 3(10)-helix contains 3.1 residues per turn, being close to the "perfect 3(10)-helix" characterized by 3.0 residues per turn. NMR and Fourier transform infrared (FTIR) spectroscopy revealed that the 3(10)-helical conformation at the atomic resolution is essentially maintained in solution. Energy minimization of peptide 1 by semiempirical molecular orbital calculation converged to a 3(10)-helical conformation similar to the x-ray crystallographic 3(10)-helix. The preference for a 3(10)-helix in the -(Aib-DeltaZPhe)4- segment is ascribed to strong inducers of the 3(10)-helix inherent in Aib and DeltaZPhe residues-in particular, the Aib residues tend to stabilize a 3(10)-helix more effectively. Therefore, the -(Aib-DeltaZPhe)4- segment is useful to rationally design an optically inactive 3(10)-helical backbone, which will be of great importance to provide novel insights into noncovalent and covalent chiral interactions of a helical peptide with a chiral molecule.