Target Identification of the Marine Natural Products Dictyoceratin-A and -C as Selective Growth Inhibitors in Cancer Cells Adapted to Hypoxic Environments.

Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. The marine spongean sesquiterpene phenols dictyoceratin-A (1) and -C (2) have been shown to induce hypoxia-selective growth inhibition in cultured cancer cells and exhibit in vivo antitumor effects. These compounds inhibit the accumulation of hypoxia-inducible factor-1α (HIF-1α), which is a drug target in hypoxia-adapted cancer cells, under hypoxic conditions. However, the target molecules of compounds 1 and 2, which are responsible for decreasing HIF-1α expression under hypoxic conditions, remain unclear. In this study, we synthesized probe molecules for compounds 1 and 2 to identify their target molecules and found that both compounds bind to RNA polymerase II-associated protein 3 (RPAP3), which is a component of the R2TP/Prefoldin-like (PEDL) complex. In addition, RPAP3-knockdown cells showed a phenotype similar to that of compound-treated cells.

Furospinosulin-1, Marine Spongean Furanosesterterpene, Suppresses the Growth of Hypoxia-Adapted Cancer Cells by Binding to Transcriptional Regulators p54(nrb) and LEDGF/p75.

Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. Cancer research has therefore focused on the identification of molecules responsible for hypoxia adaptation in cancer cells, as well as the development of new compounds with action against hypoxia-adapted cancer cells. The marine natural product furospinosulin-1 (1) has displayed hypoxia-selective growth inhibition against cultured cancer cells, and has shown in vivo anti-tumor activity, although its precise mode of action and molecular targets remain unclear. In this study, we found that 1 is selectively effective against hypoxic regions of tumors, and that it directly binds to the transcriptional regulators p54(nrb) and LEDGF/p75, which have not been previously identified as mediators of hypoxia adaptation in cancer cells.

Structure-Activity Relationship and in Vivo Anti-Tumor Evaluations of Dictyoceratin-A and -C, Hypoxia-Selective Growth Inhibitors from Marine Sponge.

Oral dictyoceratin-C (1) and A (2), hypoxia-selective growth inhibitors, showed potent in vivo antitumor effects in mice subcutaneously inoculated with sarcoma S180 cells. Structurally modified analogs were synthesized to assess the structure-activity relationship of the natural compounds 1 and 2 isolated from a marine sponge. Biological evaluation of these analogs showed that the exo-olefin and hydroxyl and methyl ester moieties were important for the hypoxia-selective growth inhibitory activities of 1 and 2. Thus far, only substitution of the methyl ester with propargyl amide in 1 was found to be effective for the synthesis of probe molecules for target identification.

Enantioselective synthesis of dictyoceratin-A (smenospondiol) and -C, hypoxia-selective growth inhibitors from marine sponge.

Total syntheses of (+)-dictyoceratin-C (1) and (+)-dictyoceratin-A (smenospondiol) (2), hypoxia-selective growth inhibitors isolated from marine sponge, were executed. The absolute stereochemistry of the each compound was determined through the enantioselective total syntheses of them. It revealed that the unnatural enantiomers of them also exhibited the hypoxia-selective growth inhibitory activity against human prostate cancer DU-145 cells.

Marine spongian sesquiterpene phenols, dictyoceratin-C and smenospondiol, display hypoxia-selective growth inhibition against cancer cells.

In the course of our search for hypoxia-selective growth inhibitors against cancer cells, a sesquiterpene phenol, dictyoceratin-C (1), was isolated from the Indonesian marine sponge of Dactylospongia elegans under the guidance of the constructed bioassay. Dictyoceratin-C (1) inhibited proliferation of human prostate cancer DU145 cells selectively under hypoxic condition in a dose-dependent manner at the concentrations ranging from 1.0 to 10 µM. The subsequent structure-activity relationship study using nine sesquiterpene phenol/quinones (2-10), which were isolated from marine sponge, was executed. We found that smenospondiol (2) also exhibited the similar hypoxia-selective growth inhibitory activity against DU145 cells, and the para-hydroxybenzoyl ester moiety would be important for hypoxia-selective growth inhibitory activity of 1. In addition, the mechanistic analysis of dictyoceratin-C (1) revealed that the 10 µM of 1 inhibited accumulation of Hypoxia-Inducible Factor-1α under hypoxic condition.

Synthesis and evaluation of effective photoaffinity probe molecule of furospinosulin-1, a hypoxia-selective growth inhibitor.

The synthesis and evaluation of a photoaffinity probe molecule for furospinosulin-1, a hypoxia-selective growth inhibitor that we identified from marine sponge, was studied. An analogue carrying an alkyne tail showed potent hypoxia-selective inhibitory activity exceeding that of the parent molecule, and exhibited in vivo anti-tumor activity following oral administration. The alkyne moiety in the analogue was also found to be a good anchoring group for the preparation of probe molecules; a photoaffinity probe molecule having an optimized spacer length was selected through the systematic synthesis of several probes and the evaluation of their hypoxia-selective growth inhibitory activity and electrophoretic mobility shift properties.

Creation of readily accessible and orally active analogue of cortistatin a.

Syntheses of structurally simplified analogues of cortistatin A (1), a novel antiangiogenic steroidal alkaloid from Indonesian marine sponge, and their biological activities were investigated. The analogues were designed by considering the 3-D structure of 1. Compound 30, in which the isoquinoline moiety was appended to the planar tetracyclic core structure, showed potent antiproliferative activity against human umbilical vein endothelial cells (HUVECs) together with high selectivity and also showed in vivo antiangiogenic activity and significant antitumor effect by oral administration.

Anti-angiogenic effect of triterpenoidal saponins from Polygala senega.

Senegasaponins [senegin II (1), senegin III (2), senegin IV (3), senegasaponin a (4), and senegasaponin b (5)] from Polygala senega were re-discovered as selective anti-proliferative substances against human umbilical vein endothelial cells (HUVECs). Senegasaponins (1-5) showed anti-proliferative activity against HUVECs with IC(50) values in the range 0.6-6.2 µM, and the selective index was 7-100-fold in comparison with those for several cancer cell lines, while the desacyl mixture of senegasaponins (6) and tenuifolin (7) lost anti-proliferative activity, indicating that the 28-O-glycoside moiety and methoxycinnamoyl group were essential for the HUVEC-selective growth inhibition of senegasaponins. Senegin III (2) inhibited the vascular endothelial growth factor (VEGF)-induced in vitro tubular formation of HUVECs and basic fibroblast growth factor (bFGF)-induced in vivo neovascularization in the mouse Matrigel plug assay. Moreover, senegin III (2) suppressed tumor growth in the ddY mice s.c.-inoculated murine sarcoma S180 cells. The analysis of the action mechanism of senegin III (2) suggested that the induction of pigment epithelium-derived factor (PEDF) would contribute to the anti-angiogenic effects of senegasaponins.

Effect of perceptual learning on motor skills of hands: a functional magnetic resonance imaging study.

Our aim was to clarify the mechanism by which perceptual learning improves motor skills of hands. We included 18 healthy volunteers (age 21.3 ± 0.3 years, mean ± standard deviation) in the study with a crossover design. The subjects were randomly classified into 3 groups, and they performed a 2-ball quick rotation task with a hand. The role of perceptual learning in improving the ability to discern the length of a wooden stick held between the left thumb and index finger was studied between the first and second sessions of the task in group A, and between the second and third sessions in groups B and C with a period of rest interval between the first and second sessions. Functional magnetic resonance imaging (fMRI) was performed for each group during the perceptual learning session. The effect of intervention, in the form of perceptual learning, on the task performance was significantly greater than that of non-intervention in all subjects (p = 0.022). Among all the activated brain areas, the bilateral prefrontal cortices, right premotor area, right supplementary motor area, right primary sensory area, right primary motor area, right inferior parietal lobe, right thalamus, and left cerebellar posterior lobe showed positive correlations between the respective contrasts from the single-subject analysis and the behavioral data before and after the interventions (p < 0.001). This result indicates a pivotal role of the frontoparietal or frontocerebellar circuits in sensorimotor integration; a specific approach that activates these circuits should be developed for clinical rehabilitation of patients.

Hypoxia-selective growth inhibition of cancer cells by furospinosulin-1, a furanosesterterpene isolated from an Indonesian marine sponge.

It is generally accepted that cancer cells, which have adapted to the hypoxic environments in tumor tissues, aggravate cancer pathology by promoting tumor growth, angiogenesis, metastasis, and drug resistance. Therefore, compounds that selectively inhibit the growth of tumor cells in hypoxic environments are expected to provide new leads for promising anticancer drugs. Furospinosulin-1, a marine-sponge-derived furanosesterterpene, exhibited selective antiproliferative activity against DU145 human prostate cancer cells under hypoxic conditions in concentrations ranging from 1 to 100 µM. Furospinosulin-1 also demonstrated antitumor activity at 10-50 mg kg(-1) oral administration in a mouse model inoculated with sarcoma S180 cells. Mechanistic analysis revealed that furospinosulin-1 suppresses transcription of the insulin-like growth factor-2 gene (IGF-2), which is selectively induced under hypoxic conditions through prevention of the binding of nuclear proteins to the Sp1 consensus sequence in the IGF-2 promoter region.

Comparison of the diagnostic performance of FDG-PET and VBM-MRI in very mild Alzheimer's disease.

PURPOSE: The aim of this study was to compare the diagnostic performance of( 18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and voxel-based morphometry (VBM) on magnetic resonance imaging (MRI) in the same group of patients with very mild Alzheimer's disease (AD). METHODS: Thirty patients with very mild AD (age 67.0+/-5.8 years; MMSE score 25.5+/-1.2, range 24-28), 32 patients with mild AD (age 67.0+/-4.5 years, MMSE score 22.1+/-0.8, range 21-23) and 60 age- and sex-matched normal volunteers underwent both FDG-PET and three-dimensional spoiled gradient echo MRI. Statistical parametric mapping was used to conduct voxel by voxel analysis and Z score mapping. First, the region of interest (ROI) maps of significant reductions in glucose metabolism and grey matter density in the mild AD patients were defined. Secondly, analysis of receiver operating characteristic (ROC) curves for Z scores in the ROI maps discriminating very mild AD patients and normal controls was performed. RESULTS: In mild AD patients, FDG-PET indicated significant reductions in glucose metabolism in the bilateral posterior cingulate gyri and the right parietotemporal area, while VBM analysis showed a significant decrease in grey matter volume density in the bilateral amygdala/hippocampus complex, compared with the normal control group. ROC analysis showed that in very mild AD patients the accuracy of FDG-PET diagnosis was 89% and that of VBM-MRI diagnosis was 83%. The accuracy of the combination of FDG-PET and VBM-MRI diagnosis was 94%. CONCLUSION: In very mild AD, both FDG-PET and VBM-MRI had high accuracy for diagnosis, but FDG-PET showed slightly higher accuracy than VBM-MRI. Combination of the two techniques will yield a higher diagnostic accuracy in very mild AD by making full use of functional and morphological images.

Voxel-based morphometric comparison between early- and late-onset mild Alzheimer's disease and assessment of diagnostic performance of z score images.

BACKGROUND AND PURPOSE: Voxel-based morphometry (VBM), used for detecting brain atrophy, permits comparison of local gray matter concentration at every voxel in an image between two groups. We sought to delineate the specific patterns of cerebral gray matter loss with regard to onset of Alzheimer's disease (AD) by using MR imaging and VBM and to evaluate the diagnostic performance of VBM with Z score images. METHODS: Two groups of 30 patients with mild AD of different ages of onset were examined. Mean ages in the early- and late-onset groups were 60.2 +/- 5.2 and 71.5 +/- 2.6 years, respectively. Control subjects were aged-matched healthy volunteers. Regions of gray matter loss in early- and late-onset AD were examined with VBM. Diagnostic performance of Z score images obtained with the VBM method was evaluated in patients and control subjects by calculating the area under the receiver operating characteristic curve (A(z)). RESULTS: Both AD groups had significantly reduced gray matter in the bilateral medial temporal regions. In addition, the early-onset group had more severe gray matter loss in the bilateral parietal and posterior cingulate cortices and precuneus region. No difference was noted in diagnostic performance of Z score images between the early- (A(z) = 0.9435) and late-onset (A(z) = 0.9018) groups. CONCLUSION: Differences were noted in the patterns of regional gray matter loss in patients with early-onset AD versus those with late-onset AD. Parietotemporal and posterior cingulate gray matter loss was found in early-onset AD but not in late-onset AD. Z score images obtained with VBM had a great diagnostic performance for mild AD and can be applied for detecting mild AD in clinical examinations.

Specific brain activation in Japanese and Caucasian people to fearful faces.

Different regions of brain activation, as measured by fMRI, were evident in Japanese and Caucasian individuals observing facial expressions categorized as fearful according to Ekman criteria. Activation was evident in the posterior cingulate, supplementary motor cortex and the amygdala in Caucasians, while activation was evident in the right inferior frontal, premotor cortex and left insula and in Japanese individuals. The results suggest that Caucasians respond to fearful faces in a more direct, emotional way, whereas Japanese do not attach an emotional valence to the faces and therefore activate a template matching system to identify facial expressions. The faces widely used as emotional stimuli therefore are not universally perceived, and cultural specificity should be taken into consideration in designing facial tasks.

Functional connectivity revealed by single-photon emission computed tomography (SPECT) during repetitive transcranial magnetic stimulation (rTMS) of the motor cortex.

OBJECTIVE: In the present study, we studied effects of 1 Hz repetitive transcranial magnetic stimulation (rTMS) over the left primary motor cortex (M1) on regional cerebral blood flow (rCBF) using single-photon emission computed tomography (SPECT). METHODS: SPECT measurements were carried out under two experimental conditions: real and sham stimulation. In sham stimulation, to exclude other components besides currents in the brain in rTMS, we applied sound and electrical stimulation to the skin of the head. 99mTc-ethyl cysteinate dimer was injected during the real or sham stimulation. Images were analyzed with the statistical parametric mapping software (SPM99). Relative differences in adjusted rCBF between two conditions were determined by a voxel-by-voxel paired t test. RESULTS: 1 Hz rTMS at an intensity of 1.1 x active motor threshold evoked increase of rCBF in the contralateral (right) cerebellar hemisphere. Reduction of rCBF was observed in the contralateral M1, superior parietal lobule (most probably corresponding to PE area in the monkey) (Rizzolatti G, Luppino G, Matelli M. Electroenceph clin Neurophysiol 1998;106:283-296), inferior parietal lobule (PF area in the monkey (Rizzolatti et al., 1998)), dorsal and ventral premotor areas (dPM, vPM) and supplementary motor area (SMA). CONCLUSIONS: Increase of rCBF in the contralateral cerebellum must reflect facilitatory connection between the motor cortex and contralateral cerebellum. Reduced rCBF in the contralateral M1 may be produced by transcallosal inhibitory effect of the left motor cortical activation. CBF decrease in the right PM, SMA and parietal cortex may reflect some secondary effects. Low frequency rTMS at an intensity of around threshold for active muscles can evoke rCBF changes. SIGNIFICANCE: We demonstrated that rCBF changes could be elicited even by low frequency rTMS at such a low intensity as the threshold for an active muscle. Combination of rTMS and SPECT is one of powerful tools to study interareal connection within the human brain.

Gender differences in cerebral glucose metabolism: a PET study.

OBJECTIVE: Some studies have examined gender differences in brain function based on cerebral blood flow and cerebral metabolism by using positron emission tomography (PET). However, the findings of these studies are controversial and most of them were analyzed by the regions of interest (ROIs) method. Here, we evaluated gender differences of cerebral glucose metabolism under the resting state in a voxel-based analysis. METHODS: We studied 44 healthy volunteers (22 females, 63.0+/-6.3 years, and 22 males, 63.1+/-8.4 years). Cerebral glucose metabolic images were obtained with (18)F-fluorodeoxyglucose (FDG) and PET. All individual data were transformed to standard brain space and the male and female groups were compared using statistical parametric mapping (SPM). RESULTS: The males had significantly higher glucose metabolism in the right insula, middle temporal gyrus, and medial frontal lobe than the females. Glucose metabolism in the hypothalamus was significantly higher in females than in males. There was a significant correlation between aging and glucose metabolism in the left thalamus in males and in the left caudate nucleus and hypothalamus in females. In males, but not females, there was a significant asymmetry between the bilateral hemispheres. CONCLUSION: We found that there were obvious gender differences in regional cerebral glucose metabolism and this is the first report of higher glucose metabolism in the hypothalamus in females than in males.