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.

Auditory brainstem response (ABR) is a useful method in evaluating auditory function in human. To investigate the ABR threshold is more effective than to pursue the trends in each component of ABR. In this study, tone burst sound stimuli were employed and the ABR threshold shift caused by kanamycin administration was investigated in dogs. In a series of monitoring of ABR against short-period auditory lesions, changes in the ABR waveform after intravenous administration of kanamycin were detected. These changes returned gradually and were reversible. The changes in ABR against long-period auditory function disorder were perceived by an increase in the ABR threshold. The ABR threshold shift occurred earlier in the high frequency sounds than in the lower frequency sounds. This is why amino glycoside antibiotics damage the cochlear hair cells in the basal layer and lead to the loss of hearing selectively for high frequency tones. These findings suggest that tracing of the ABR threshold by tone bursts could provide information that has a specificity for frequency in hearing tests and is a useful method in clinical veterinary medicine or/and toxicological tests.

Starting materials of phosphasugars, 1-phenyl-2-phospholene 1-oxides, were prepared from dienes and phenylphosphonous dichloride (dichlorophenylphosphine). Several substituted novel phosphasugars (3- or 4-halo-substituted)-1-phenyl-2-phospholene 1-oxides as well as 1-phenyl-2-phospholane 1-oxides were prepared from 2-phospholenes. The synthesized compounds were evaluated for their antitumor activities against the leukemia cell lines (U937 and K562) by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. 2,3,4-Tribromo-3-methyl-1-phenylphospholane 1-oxide showed superior antitumor activity against U937 and K562 cell lines in a comparative evaluation with Glivec. The analysis by flow cytometry implied that 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide induced apoptosis to leukemia cell lines.

Novel broad spectrum low-molecular-weight antitumor agents of phospha sugar derivatives were investigated and developed. Branched deoxybromophospha sugars, such as DBMPP and TBMPP, which target IER5/Cdc25B and innovate in chemo-therapeutic treatments against various type of cancer cells. These successful preclinical in vitro and in vivo evaluations observed might be expected to afford clinically useful drugs and innovative medical treatments for various kinds of cancers.

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.