22R-Hydroxycholesterol induces differentiation of human NT2 precursor (Ntera2/D1 teratocarcinoma) cells

Recently, we have shown that 22R-hydroxycholesterol, a steroid intermediate in the pathway of pregnenolone formation from cholesterol, is present at lower levels in Alzheimer's disease (AD) hippocampus and frontal cortex tissue specimens than in age-matched controls, and that this substance protects against cell death induced by amyloid beta-peptide in both rat sympathetic nerve pheochromocytoma (PC12) and differentiated human Ntera2/D1 teratocarcinoma neurons. Herein we report that 22R-hydroxycholesterol inhibits the proliferation of human Ntera2/D1 teratocarcinoma precursor cells (NT2) and induces these cells to differentiate into "neuron-like" or "astrocyte-like" cells. 22R-Hydroxycholesterol-induced differentiation of NT2 cells is associated with increases in the expression of neurofilament protein NF200, the cytoskeletal proteins microtubule-associated protein type II (MAP2) a and MAP2b, glial fibrillary acidic protein (GFAP) and glial cell line-derived neurotrophic factor receptor-alpha 2 (GFRalpha2). These effects of 22R-hydroxycholesterol are considered to be stereospecific because its enantiomer 22S-hydroxycholesterol and other steroids failed to induce differentiation of NT2 cells. 22R-Hydroxycholesterol was found to lack specific binding for numerous receptors, including all steroid receptors tested. However, using a cholesterol protein binding blot assay we demonstrated the presence of a 22R-hydroxycholesterol-binding protein in NT2 cells distinct from the human oxysterol receptors liver X receptor LXRalpha and beta.

Phospho Akt mediates multidrug resistance of gastric cancer cells through regulation of P-gp, Bcl-2 and Bax

Phosphatidylinositol 3-kinase/Akt pathway is an important intracellular pathway that is frequently activated in cancer cells. The role of P-AKT in multidrug resistance of gastric cancer cells and the possible underlying mechanisms are here investigated. Up-regulation of P-AKT expression could confer resistance to both P-glycoprotein-related and P-glycoprotein-non-related drugs on AGS cells, and suppress adriamycin-induced apoptosis, along with decreased accumulation and increased releasing amount of adriamycin. P-AKT could significantly up-regulate the expression of Bcl-2, and down-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. Inhibition of P-AKT expression could partially reverse P-AKT-mediated multidrug resistance and significantly up-regulate P53 expression, and down-regulate the expression of P-glycoprotein and the transcription of the multidrug resistance gene 1. Further studies of the biological functions of P-AKT may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible therapeutical strategies.

Disrupting mitochondrial function with surfactants inhibits MA-10 Leydig cell steroidogenesis

It is well established that surfactants can elicit cytotoxic effects at threshold concentrations by changing the permeability and solubilizing components of cell membranes. The purpose of this study was to characterize the relationship between perturbation of the mitochondrial membrane resulting from treatment with representative cationic, nonionic, and anionic surfactants and the extent to which this perturbation affects steroid formation and StAR protein expression and activity in MA-10 Leydig cells. The StAR protein is synthesized as an active 37 kDa extramitochondrial form, which is processed into a 30 kDa intramitochondrial form after cholesterol transfer and mitochondrial import and processing. It has been shown in several in vitro studies that the mitochondrial electrochemical gradient is required for the StAR protein to transfer cholesterol to the inner mitochondrial membrane. Each substance that was tested produced a concentration-dependent decrease in steroid formation in hCG-stimulated MA-10 cells. Decreases in progesterone production were accompanied by loss of mitochondrial membrane potential and by a decrease in the levels of the 30 kDa form of the StAR protein. However, levels of the 37 kDa form of the StAR protein did not decrease, indicating no effect on StAR protein expression. These results demonstrate how perturbation of the mitochondrial membrane by surfactants inhibits import, processing, and cholesterol transfer activity and underscore the importance of including sensitive assays that evaluate mitochondrial function when screening for potential effects on steroidogenesis with in vitro test systems.

Antiproliferative activity and induction of apoptosis in human colon cancer cells treated in vitro with constituents of a product derived from Pistacia lentiscus L. var. chia

In this report, we demonstrate that a 50% ethanol extract of the plant-derived product, Chios mastic gum (CMG), contains compounds which inhibit proliferation and induce death of HCT116 human colon cancer cells in vitro. CMG-treatment induces cell arrest at G(1), detachment of the cells from the substrate, activation of pro-caspases-8, -9 and -3, and causes several morphological changes typical of apoptosis in cell organelles. These events, furthermore, are time- and dose-dependent, but p53- and p21-independent. Apoptosis induction by CMG is not inhibited in HCT116 cell clones expressing high levels of the anti-apoptotic protein, Bcl-2, or dominant-negative FADD, thereby indicating that CMG induces cell death via a yet-to-be identified pathway, unrelated to the death receptor- and mitochondrion-dependent pathways. The findings presented here suggest that CMG (a) induces an anoikis form of cell death in HCT116 colon cancer cells that includes events associated with caspase-dependent pathways; and (b) might be developed into a chemotherapeutic agent for the treatment of human colon and other cancers.

Spontaneous basilar artery dissection

Dissection of the basilar artery is rare. We report a 51-year-old man who developed acute pontine infarction associated with dissection of the distal basilar artery. There was no trauma or unaccustomed movement of the head and neck prior to the stroke. The dissection was diagnosed non-invasively by magnetic resonance imaging and magnetic resonance angiography. Cervicocerebral artery dissection is a common cause of stroke in young patients particularly when conventional cardiovascular risk factors are absent. Magnetic resonance angiography combined with magnetic resonance imaging is a useful diagnostic tool prior to invasive angiography.

Reversal of multidrug resistance of gastric cancer cells by downregulation of Akt1 with Akt1 siRNA

Phosphatidylinositol 3-kinase/AKT1 pathway was an important intracellular pathway that was frequently activated in cancer cells. In the present study, we constructed the siRNA eukaryotic expression vectors of AKT1 and transfected them into AGS cells to examine whether the down-regulation of AKT1 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of AKT1 was dramatically decreased in AKT1 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of AKT1 could significantly enhance the sensitivity of AGS cells to vincristine, adriamycin, 5-fludrouracil and cisplatin. AKT1 siRNA could significantly down-regulate the expression of Bcl-2, and up-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. These observations suggested that the siRNA constructs of AKT1 we obtained could effectively down-regulate the expression of AKT1 and reverse the resistant phenotype of gastric cancer cells. The further study of the biological functions of AKT1 may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible strategies to treat gastric cancer.

Zinc ribbon domain containing 1 protein: modulator of multidrug resistance, tumorigenesis and cell cycle

Zinc ribbon domain containing 1 (ZNRD1) gene encoding a protein consisting of two zinc ribbon domains was recently cloned from the human HLA locus. So far, ZNRD1 has been found implicated in transcription regulation and might play potential roles in mediating several biological processes, including multidrug resistance, tumorigenesis and cell cycle. This article reviewed these recent findings and provided additional information to support the role of ZNRD1 gene as a novel candidate DNA damage repair related gene.

OncoVEX: A family of oncolytic herpes simplex viruses optimised for therapeutic use

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HSV in which ICP34.5 is deleted directs tumour selective cell lysis and has proven safe in Phase I clinical trials. To produce oncolytic HSV with enhanced anti-tumour properties, we have deleted ICP34.5 from a clinical isolate of HSV-1, which enhances the tumour cell killing capabilities of the virus, deleted ICP47 (which blocks antigen presentation), and inserted the gene encoding GM-CSF. This aimed to maximize anti-tumour immune responses following intra-tumoural injection and provide an in situ, patient-specific, anti-tumour vaccine, combined with oncolysis. In vivo, both injected and non-injected tumours could be cured and animals were then protected against tumour cell challenge. A Phase I clinical trial with the virus (OncoVEXGM-CSF) has been conducted including patients with cutaneous or sub-cutaneous deposits of a number of tumour types (Lead Investigator: Professor Charles Coombes, Hammersmith Hospital, London). This demonstrated the virus to have a good safety profile, the main side effects being ‘flu-like symptoms, similar to those which have previously been observed with other oncolytic products. Virus replication and GM-CSF expression was demonstrated together with inflammation, flattening and necrosis of injected lesions which was in some cases considerable and which was also in some cases observed in lesions which had not themselves been injected. In all cases where necrosis was observed in biopsies, this correlated with areas of staining for HSV, suggesting the virus had caused the effect. Following this promising data, Phase II studies are underway in multiple tumour types. In addition to OncoVEXGM-CSF, further versions of OncoVEX expressing other active genes have been constructed and tested in pre-clinical models. These include a virus expressing TNF∝, intended to be synergistic with radiotherapy, and versions of the virus expressing a pro-drug activating gene combined with the delivery of a fusogenic glycoprotein designed to maximize the properties of the virus for local tumour control. Each of these have shown promising results in pre-clinical tumour models, including in combination with chemotherapy and radiotherapy where benefits which are at least additive have been demonstrated.

[Table: see text]

Differential susceptibility to etoposide in clones derived from a human ovarian cancer cell line

OBJECTIVES

To identify parameters/factors that may contribute to the differential sensitivity to etoposide in two clones isolated from the human ovarian carcinoma SKOV-3 cell line, which does not express p53 and is resistant to platinum-based regimens.

METHODS

Differential sensitivity of the cells to etoposide was monitored by microscopy to observe morphological changes, by flow cytometry analyses to detect cell cycle perturbations, and by molecular/biochemical assays to identify events involved in induction of apoptosis.

RESULTS

Etoposide treatment (1) induced apoptosis in one clone, ES, but not in another clone, ER, (2) had no effect on the expression of the antiapoptotic proteins Bcl-2 and Bcl-X(L) in both cell clones, whereas the proapoptotic proteins Bak and Bax were dramatically upregulated in ES, but not ER cells, and (3) induced more extensive processing of procaspase-8, procaspase-9, and the caspase-3-targeted substrates, topoisomerase I and PARP, in ES cells. Ectopic overexpression of Bcl-2 in ES cells failed to inhibit etoposide-induced apoptosis.

CONCLUSIONS

The differential susceptibility of ES and ER cells to etoposide-induced apoptosis is associated with differences in several events rather than with a specific single genetic regulator of the apoptotic machinery. We propose that the differential response of ovarian cancer patients to etoposide treatment is associated with the number of etoposide-sensitive cells in the tumor.

Detection and identification of avian, duck, and goose reoviruses by RT-PCR: goose and duck reoviruses are part of the same genogroup in the genus Orthoreovirus

A reverse transcription-polymerase chain reaction (RT-PCR) procedure for the detection of avian, duck, and goose reovirus (ARV, DRV, and GRV) RNA from cell culture supernatant and clinical samples was established. Based on multiple sequence alignment, a pair of degenerate primers was selected and synthesized. The amplified, cloned, and sequenced 598-base-pair products from the sigmaA-encoding gene fragment from 16 isolates (ranging over 30 years) indicated that the primer regions were well conserved. The sensitivity of this method was determined to be 10(-2) PFU. The specificity of the RT-PCR method was determined by testing specimens containing avian influenza A viruses, Newcastle disease virus, and infectious bronchitis virus, all of which yielded negative results with no discernible background. The efficiency of the system for detection of ARV, DRV, and GRV directly in 71/83 clinical samples was confirmed. The nucleotide sequence analysis indicated that DRV and GRV isolated from China in different locales and years were closely related, showing 97.4-100% homology to each other, but with only 86.7-88.5% identity to DRV 89026. The nucleotide and amino acid sequence identities in the amplified sigmaA-encoding gene were 74.2-78.4% and 86.9-92.0%, respectively, between duck/goose and chicken species. Phylogenetic analysis indicated that GRV and DRV aggregated into the same specified genogroup within subgroup II of the genus Orthoreovirus and are more closely related to ARV than to Nelson Bay virus. Overall, this study developed a sensitive and specific technique for the identification ARV, DRV, and GRV, and sequencing analysis has enhanced our understanding of the evolutionary relationship between ARV, DRV, and GRV.

Peripheral-type benzodiazepine receptor in neurosteroid biosynthesis, neuropathology and neurological disorders

The peripheral-type benzodiazepine receptor is a mitochondrial protein expressed at high levels in steroid synthesizing tissues, including the glial cells of the brain. Peripheral-type benzodiazepine receptor binds cholesterol with high affinity and is a key element of the cholesterol mitochondrial import machinery responsible for supplying the substrate cholesterol to the first steroidogenic enzyme, thus initiating and maintaining neurosteroid biosynthesis. Neurosteroid formation and metabolism of steroid intermediates are critical components of normal brain function. Peripheral-type benzodiazepine receptor also binds with high affinity various classes of compounds. Upon ligand activation peripheral-type benzodiazepine receptor-dependent cholesterol transport into mitochondria is accelerated leading in increased formation of neuroactive steroids. These steroids, such as allopregnanolone, have been shown to be involved in various neurological disorders, such as anxiety and mood disorders. Thus, peripheral-type benzodiazepine receptor drug ligand-induced neuroactive steroid formation offers a means to regulate brain dysfunction. Peripheral-type benzodiazepine receptor basal expression is upregulated in a number of neuropathologies, including gliomas and neurodegenerative disorders, as well as in various forms of brain injury and inflammation. In Alzheimer's disease pathology neurosteroid biosynthesis is altered and a decrease in the intermediate 22R-hydroxycholesterol levels is observed. This steroid was found to exert neuroprotective properties against beta-amyloid neurotoxicity. Based on this observation, a stable spirostenol derivative showing to display neuroprotective properties was identified, suggesting that compounds developed based on critical intermediates of neurosteroid biosynthesis could offer novel means for neuroprotection. In conclusion, changes in peripheral-type benzodiazepine receptor and neurosteroid levels are part of the phenotype seen in neuropathology and neurological disorders and offer potential targets for new therapies.

Effects of alginate encapsulation on mitochondrial activity

The long-term objective of our research is to study the biochemical consequences of primary genetic defects of the Pyruvate Dehydrogenase Complex, a key mitochondrial enzyme complex, by NMR spectroscopy. An established method to obtain energetic and metabolic information from intact cells involves the use of 31P and 13C NMR spectroscopic techniques. NMR spectra from live and fully functional cells can be obtained from cells encapsulated within alginate beads and maintained in a perfusion bioreactor throughout the NMR experiment. However, before spectroscopic studies can commence, the effects of alginate encapsulation on the general metabolism and mitochondrial activity of fibroblasts need to be determined. in this study we report glucose consumption and flow cytometry measurements (with the fluorescent markers MitoTracker GreenFM and Nonyl-acridine Orange to determine the mitochondrial status and mass) of healthy human fibroblasts encapsulated in a mannuronic acid-rich alginate matrix. The results show that alginate encapsulation of fibroblasts does not affect the glucose consumption, the mitochondrial integrity, or the mitochondrial mass during 21 days of in vitro culture.

Helix 6 of tBid is necessary but not sufficient for mitochondrial binding activity

The apoptosis effector Bid regulates cell death at the level of mitochondrial cytochrome c efflux. Bid consists of 8 alpha-helices (designated H1 through H8, respectively) and is a soluble cytosolic protein in its native state. Proteolysis of the N-terminus (encompassing H1 and H2) of Bid yields activated "tBid" (truncated Bid), which translocates to the mitochondria and induces the efflux of cytochrome c. Here, we demonstrate that helix H6 of tBid is necessary, albeit not sufficient, for mitochondrial binding. In particular, a 33 amino acid long domain, which encompassed H6 and H7, behaved as the minimum domain in tBid that was sufficient for mitochondrial binding. Unexpectedly, the hydrophobic surface of these helices could be mutated without altering the binding activity of the domain, implying that the secondary structure of the helices may be the key determinant of binding. These experiments expand our mechanistic understanding of the apoptotic regulator, tBid.

Expression of matrix metalloproteinases MMP-9 within the airways in asthma

The matrix metalloproteinase (MMP) enzymes MMP-9, have relevance to chronic structural airway changes in asthma, which can be generated by structural and inflammatory cells, and have the ability to degrade proteoglycans and thus potentially enhance airway fibrosis and smooth muscle proliferation through their ability to release and activate latent, matrix-bound growth factors. Immunostaining for MMP-9 was undertaken in acetone-fixed and glycolmethacrylate-embedded endobronchial biopsy specimens obtained by fibreoptic bronchoscopy under local anaesthesia. The findings from 30 asthmatic subjects were compared with those from 18 chronic obstructive pulmonary disease (COPD) subjects and 10 healthy controls. Meanwhile, pulmonary function test and airway responsiveness were performed. Immunoreactivity for MMP-9 was assessed by an image analysis system. The biopsy specimens from asthmatic subjects contained significantly more eosinophils (P < 0.001) than those from COPD subjects, and healthy control did not contain eosinophils. MMP-9 immunoreactivity could be identified in endobronchial biopsy specimens from all the asthmatic subjects and 40% ofthe COPD subjects, but could not be identified in healthy controls. Gelatinase B (MMP-9) immunoreactivity was located in bronchial epithelium and extracellular matrix in submucosa, prominent in denuded epithelium. The immunohistochemical score for MMP-9 was significantly correlated with eosinophilic number in bronchial mucosa. FEV1% predicted FEV1/FVC (%) (r = 0.52, 0.41, 0.37, respectively P < 0.01 did not correlate with PD20 FEV1 from asthmatic subjects. MMP-9 is expressed by bronchial epithelium and may be a important factor for eosinophil infiltraed into airway from asthma subjects.

[Fatal side-effects of all-trans retinoic acid in the treatment of acute promyelocytic leukemia]

Of 82 patients with acute promyelocytic leukemia (APL) who were treated with all-trans retinoic acid (ATRA), 35 developed leukocytosis and 22 fatal side-effects(15 with retinoic acid syndrome and 7 intracranial bleeding). There was a high mortality in the patient with fatal side-effects. The relationship between leukocytosis and fatal side-effects was analyzed and the effect of therapeutic interventions on the development and prognosis of the fatal side-effects was investigated. The results showed that leukocytosis was a risk factor of the development of fatal side-effects in APL treated with ATRA. ATRA combined with small dose of harringtonin in treating APL can reduce the incidence of intracranial bleeding resulted from leukocytosis and corticosteroid can decrease the mortality of retinoic acid syndrome.

[Use of microsatellites in zygosity diagnosis of twins]

OBJECTIVE

To diagnose zygosity of twins by microsatellite polymorphism.

METHODS

One hundred and eighty-four samples, including 69 pairs of twins with the same gender and 6 pairs of twins with different gender were recruited. Seventeen sib pairs were also collected for controls. Nine highly polymorphic microsatellite loci were amplified by polymerase chain reaction (PCR) using fluorescence-labeled primers and the products were sized by automated fragment analysis after electrophoresis and laser detection. Zygosity was diagnosed by comparing the concordance of the genotype of the 9 markers.

RESULTS

Sixty-three pairs of monozygotic (MZ) and 12 pairs of dizygotic (DZ) twins were assigned their zygosity by comparison of polymorphism of 9 microsatellite loci. Within each of the 63 monozygotic (MZ) pairs there was complete concordance. However, within each of the 12 dizygotic pairs and other 17 sib pairs, discordant loci were found. With five or six markers, the probability that any twin pair was MZ if all markers were concordant was 99% or 99.6%, respectively. With all the nine markers, the probability that any twin pair was MZ if all markers were concordant was 99.95%.

CONCLUSION

The technology of gene scan and genotyping provides a rapid and reliable approach to zygosity detection.