Increased Expression of NPM1 Suppresses p27Kip1 Function in Cancer Cells.

p27Kip1, a major cyclin-dependent kinase inhibitor, is frequently expressed at low levels in cancers, which correlates with their malignancy. However, in this study, we found a qualitative suppression of p27 overexpressed in some cancer cells. By proteomic screening for factors interacting with p27, we identified nucleophosmin isoform 1 (NPM1) as a novel p27-interacting factor and observed that NPM1 protein was expressed at high levels in some cancer cells. NPM1 overexpression in normal cells suppressed p27 function, and conversely, NPM1 knockdown in cancer cells restored the function in vitro. Furthermore, the tumors derived from cancer cells carrying the combination of p27 overexpression and NPM1 knockdown constructs showed significant suppression of growth as compared with those carrying other combinations in mouse xenograft models. These results strongly suggest that increased expression of NPM1 qualitatively suppresses p27 function in cancer cells.

An automated voxel-based method for calculating the reference value for a brain tumour metabolic index using 18F-FDG-PET and 11C-methionine PET.

OBJECTIVE: The tumour-to-normal ratio (T/N) is a representative index reflecting brain tumour activity by 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) PET. We proposed a new automated method of calculating the normal reference value (N-value) for use as the denomination of T/N. This method uses voxel-based analysis of FDG- and MET-PET images. We compared the results of this method with those of the standard region-of-interest (ROI) method. METHODS: Data sets were obtained from 32 patients with newly diagnosed glioma and 13 patients with recurrent brain tumour. Our methods were as follows: (1) FDG-PET and MET-PET images were co-registered. (2) The areas where the FDG uptake was higher than a set threshold were selected. (3) For the corresponding areas of MET-PET images, mode and mean voxel values were calculated as tentative MET N-values. (4) Applying the same coordinates to FDG-PET, the voxel values were averaged and used as tentative FDG N-values. (5) The threshold of FDG-PET and whether to use the mode or the mean voxel values were computationally optimized using learning data sets. (6) Applying the optimal threshold and either the mode or mean, N-values of FDG and MET were finally determined. RESULTS: N-values determined by our automated method showed excellent agreement with those determined by a manual ROI method (ICC(2,1) > 0.78). These values were significantly correlated with mean manual N-values (p < 0.001). CONCLUSIONS: Our new method shows sufficiently good agreement with the standard method and can provide a more objective metabolic index.

Inhibition of amyloid fibril formation and cytotoxicity by caffeic acid-conjugated amyloid-ß C-terminal peptides.

Amyloid-ß (Aß) deposition and oxidative stress observed in the brains of patients with Alzheimer's disease (AD) are important targets for therapeutic intervention. In this study, we conjugated the antioxidants caffeic acid (CA) and dihydrocaffeic acid (DHCA) to Aß1-42 C-terminal motifs (Aßx-42: x=38, 40) to synthesize CA-Aßx-42 and DHCA-Aßx-42, respectively. Among the compounds, CA-Aß38-42 exhibited potent inhibitory activity against Aß1-42 aggregation and scavenged Aß1-42-induced intracellular oxidative stress. Moreover, CA-Aß38-42 significantly protected human neuroblastoma SH-SY5Y cells against Aß1-42-induced cytotoxicity, with an IC50 of 4µM. These results suggest that CA-Aß38-42 might be a potential lead for the treatment of AD.

Synthesis, in vitro and in vivo pharmacology of a C-11 labeled analog of CP-101,606, (+/-)threo-1-(4-hydroxyphenyl)-2-[4-hydroxy-4-(p-[11C]methoxyphenyl)piperidino]-1-propanol, as a PET tracer for NR2B subunit-containing NMDA receptors.

A carbon-11 labeled methoxyl analog of CP-101,606, (+/-)threo-1-(4-hydroxyphenyl)-2-[4-hydroxy-4-(p-[11C]methoxyphenyl)piperidino]-1-propanol [(+/-)[11C]1], was synthesized as a new subtype-selective PET radioligand for NMDA receptors. The in vitro binding studies using rat brain slices demonstrated that (+/-)[11C]1 shows an extremely high-specific binding to the NR2B subunit of NMDA receptors. In contrast to the in vitro binding, the in vivo binding to mouse and monkey brains showed no apparent specific localization of the radioactivity in any of the brain regions. Metabolism and physicochemical properties such as the lipophilicity of (+/-)[11C]1 seemed unlikely to affect the in vivo (+/-)[11C]1 binding. Among the various endogenous ligands acting at the NMDA receptors, polyamines (spermine and spermidine) and divalent cations (Mg(2+,) Zn(2+,) and Ca(2+)) strongly inhibited the in vitro (+/-)[11C]1 binding. Thus, the present studies point to the possibility that the polyamines and cations behave as endogenous inhibitors for (+/-)[11C]1 binding, leading to the loss of the specific binding in vivo.