Synthesis, structure, and electronic properties of the Li11RbGd4Te6O30 single crystal.

Materials with spin dimers have attracted much attention in the last several decades because they could provide a playground to embody simple quantum spin models. For example, the Bose-Einstein condensation of magnons has been observed in TlCuCl3 with anti-ferromagnetic Cu2Cl6 dimers. In this work, we have synthesized a new kind of single-crystal Li11RbGd4Te6O30 with Gd2O15 dimers. This material belongs to the rhombohedral system with the lattice parameters: a = b = c = 16.0948 Å and α = ß = γ = 33.74°. First-principles calculations indicate that Li11RbGd4Te6O30 is a wide-bandgap (about 4.5 eV) semiconductor. But unlike many other well studied quantum dimer magnets with an anti-ferromagnetic ground state, the Gd2O14 dimers in Li11RbGd4Te6O30 show ferromagnetic intra-dimer exchange interactions according to our calculations. Our work provides a new material which could possibly extend the studies of the spin dimers.

Relationship between SATB1 expression and prognosis in astrocytoma.

Special AT-rich-sequence-binding protein 1 (SATB1), a new type of gene regulator, has been reported to be expressed in various human cancers and may be associated with malignancy. The aim of this study was to investigate the expression of SATB1 in astrocytoma and to determine its prognostic value for the overall survival of patients with astrocytoma. The expression of SATB1 protein and messenger RNA (mRNA) in human astrocytoma specimens was examined using immunohistochemistry and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The relationship between SATB1 expression and O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was also investigated. Spearman's correlation coefficient was used to describe the association between SATB1 expression and the clinical parameters of astrocytoma patients. SATB1 protein and mRNA were expressed at significant levels in astrocytoma specimens. SATB1 expression was positively correlated with astrocytoma pathological grade but negatively correlated with the life span of astrocytoma patients. SATB1 expression was also significantly lower in astrocytoma specimens with MGMT promoter methylation than in those without MGMT promoter methylation. Our findings suggest that SATB1 may have an important role as a positive regulator of astrocytoma development and progression and that SATB1 might be a useful molecular marker for predicting the prognosis of patients with astrocytoma and could be a novel target for treating astrocytoma.

Upregulation of SATB1 is associated with the development and progression of glioma.

BACKGROUND: Special AT-rich sequence-binding protein-1 (SATB1) has been reported to be expressed in several human cancers and may have malignant potential. This study was aimed at investigating the expression and potential role of SATB1 in human glioma. METHOD: The relationship between SATB1 expression, clinicopathological parameters, Ki67 expression and MGMT promoter methylation status was evaluated, and the prognostic value of SATB1 expression in patients with gliomas was analyzed. SATB1-specific shRNA sequences were synthesized, and U251 cells were transfected with SATB1 RNAi plasmids. Expression of SATB1 mRNA and protein was investigated by RT-PCR and immunofluoresence staining and western blotting. The expression of c-Met, SLC22A18, caspase-3 and bcl-2 protein was determined by western blotting. U251 cell growth and adherence was detected by methyl thiazole tetrazolium assay. The apoptosis of U251 cells was examined with a flow cytometer. The adherence, invasion, and in vitro angiogenesis assays of U251 cells were done. The growth and angiogenesis of SATB1 low expressing U251 cells was measured in an in vivo xenograft model. RESULTS: Of 70 tumors, 44 (62.9%) were positive for SATB1 expression. SATB1 expression was significantly associated with a high histological grade and with poor survival in univariate and multivariate analyses. SATB1 expression was also positively correlated with Ki67 expression but negatively with MGMT promoter methylation in glioma tissues. SATB1 shRNA expression vectors could efficiently induce the expression of SLC22A18 protein, increase the caspase-3 protein, inhibit the expression of SATB1, c-Met and bcl-2 protein, the growth, invasion, metastasis and angiogenesis of U251 cells, and induce apoptosis in vitro. Furthermore, the tumor growth of U251 cells expressing SATB1 shRNA were inhibited in vivo, and immunohistochemical analyses of tumor sections revealed a decreased vessel density in the animals where shRNA against SATB1 were expressed. CONCLUSIONS: SATB1 may have an important role as a positive regulator of glioma development and progression, and that SATB1 might be a useful molecular marker for predicting the prognosis of glioma.

Effect of 5-Aza-2'-deoxycytidine on SLC22A18 in glioma U251 cells.

SLC22A18 [solute carrier family 22 (organic cation transporter) member 18] is located within the 11p15.5 cluster, and may be a new tumor suppressor gene; evidence of SLC22A18 hypermethylation is documented in several types of human cancers. In order to determine whether SLC22A18 hypermethylation is involved in glioma, we determined the SLC22A18 gene protein expression, mRNA expression and methylation status in glioma U251 cells before and after treatment with 5-Aza-2'­deoxycytidine (5-Aza-CdR), and observed the change in growth. Glioma U251 cells treated with 5-Aza-CdR were analyzed by flow cytometry to identify any change in their cell cycle profiles. Tumors induced via the injection of untreated U251 cells were measured. Immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR) and PCR-based methylation assay were carried out to determine SLC22A18 gene protein expression, mRNA expression and methylation status in glioma U251 cells before and after treatment with 5-Aza­CdR. The treated cells showed an increase in their proportion in G1, from 79.2 to 83.5%, and a decrease in S phase, from 12.4 to 5.8%. The apoptotic rate increased from 6.4 to 15.8%. Tumors induced via the injection of untreated U251 cells were approximately 1.46 cm³ in size, whereas the tumors induced by U251 cells treated with 5-Aza-CdR averaged 0.88 cm³ in size. The expression levels of SLC22A18 protein and mRNA in U251 cells were increased following treatment with 5x10⁻7 M 5-Aza­CdR. Prior to 5-Aza-CdR treatment, the SLC22A18 gene demonstrated hypermethylation and therefore could not be cleaved by HpaII and MspI. It is known that only the DNA digested with HpaII or MspI can be amplified. Following treatment with 5-Aza­CdR, the SLC22A18 gene became demethylated, and could then be cleaved by both of the enzymes, and this failed to be amplified. 5-Aza-cdR may induce glioma U251 cell division and apoptosis and enhance demethylation and protein and mRNA expression of SLC22A18. The hypermethylation of SLC22A18 may be related to the transcriptional silencing of this gene. The growth inhibitory effects of 5-Aza-CdR treatment in vivo remain recognizable.

Correlation of low SLC22A18 expression with poor prognosis in patients with glioma.

We investigated the expression of the putative tumor suppressor SLC22A18 to evaluate it as a prognostic marker in glioma patients. Immunohistochemical and Western blot analyses of clinical tissue samples obtained from 120 patients with glioma were performed. Low expression of SLC22A18 was observed in 71.7% of patients. Loss of SLC22A18 expression in glioma was significantly related to pathological grade (p = 0.003). High pathological grade (World Health Organization III-IV) was correlated with negative (low or absent) expression of SLC22A18, which was correlated with a significantly shorter overall patient survival than in those with positive (high) expression (p = 0.007). Multivariate Cox regression analysis indicated that SLC22A18 expression level is an independent survival prognostic factor for patients with glioma (p = 0.011). Western blotting analysis confirmed decreased expression of SLC22A18 in glioma tissues compared with adjacent brain tissues. This study suggests that SLC22A18 functions as a tumor suppressor in glioma and represents a candidate biomarker for long-term survival in this disease.

Promoter methylation and downregulation of SLC22A18 are associated with the development and progression of human glioma.

BACKGROUND: Downregulation of the putative tumor suppressor gene SLC22A18 has been reported in a number of human cancers. The aim of this study was to investigate the relationship between SLC22A18 downregulation, promoter methylation and the development and progression of human glioma. METHOD: SLC22A18 expression and promoter methylation was examined in human gliomas and the adjacent normal tissues. U251 glioma cells stably overexpressing SLC22A18 were generated to investigate the effect of SLC22A18 on cell growth and adherence in vitro using the methyl thiazole tetrazolium assay. Apoptosis was quantified using flow cytometry and the growth of SLC22A18 overexpressing U251 cells was measured in an in vivo xenograft model. RESULTS: SLC22A18 protein expression is significantly decreased in human gliomas compared to the adjacent normal brain tissues. SLC22A18 protein expression is significantly lower in gliomas which recurred within six months after surgery than gliomas which did not recur within six months. SLC22A18 promoter methylation was detected in 50% of the gliomas, but not in the adjacent normal tissues of any patient. SLC22A18 expression was significantly decreased in gliomas with SLC22A18 promoter methylation, compared to gliomas without methylation. The SLC22A18 promoter is methylated in U251 cells and treatment with the demethylating agent 5-aza-2-deoxycytidine increased SLC22A18 expression and reduced cell proliferation. Stable overexpression of SLC22A18 inhibited growth and adherence, induced apoptosis in vitro and reduced in vivo tumor growth of U251 cells. CONCLUSION: SLC22A18 downregulation via promoter methylation is associated with the development and progression of glioma, suggesting that SLC22A18 is an important tumor suppressor in glioma.

Expression of HGF and VEGF in the cerebral tissue of adult rats with chronic hydrocephalus after subarachnoid hemorrhage.

The hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are important cytokines with modulatory actions in the nervous system. The present study aimed to investigate the role and expression of HGF and VEGF in the cerebral tissue of adult rats with chronic hydrocephalus after subarachnoid hemorrhage. Adult female Wistar rats were randomly divided into 4 groups: a control group (n=20) and 3 experimental subgroups (n=60). Subarachnoid hemorrhage was induced by the injection of 0.4 ml of non-heparinized autologous arterial blood into the cisterna magna of experimental animals on day 0 with a second injection 2 days later. The rats were sacrificed within 24 h of magnetic resonance imaging (MRI) examination at 2, 4, or 6 weeks. The excised brains were studied by RT-PCR, immunohistochemical and Western blot analyses as we examined HGF and VEGF mRNA and protein expression. Chronic hydrocephalus was induced in 21 rats after subarachnoid hemorrhage. After 2 weeks, the expression of HGF and VEGF in the cerebral tissue was significantly increased in the experimental group compared to the controls, especially in periventricular white matter. Our results indicate that HGF and VEGF participate in the pathological injury and repair of cerebral tissue in rats with chronic hydrocephalus after subarachnoid hemorrhage.

Elevated expression of solute carrier family 22 member 18 increases the sensitivity of U251 glioma cells to BCNU.

Previous studies showed that solute carrier family 22 member 18 (SLC22A18) is involved in tumorigenesis. The aim of this study was to examine the role of SLC22A18 in glioma cells. Glioma U251 cells were transfected with the human SLC22A18 gene. Transfection of the empty vector pcDNA3.1 was used as a negative control. Sensitivity to BCNU was measured by Annexin V staining. The expression of caspase-3 and bcl-2 was determined by immunohistochemistry. The transfection was confirmed by PCR, RT-PCR and Western blotting. Augmented apoptotic cell death was observed in the SLC22A18-transfected cells, compared to the non-transfected cells or cells with the empty vector. Caspase-3 expression increased in U251-SLC22A18 cells, whereas the bcl-2 expression decreased. These results indicated that SLC22A18 has a pro-apoptotic function in glioma cells.

c-Met antisense oligodeoxynucleotides increase sensitivity of human glioma cells to paclitaxel.

Cell culture, tissue chemistry and flow cytometry were used to determine whether antisense c-Met oligodeoxynucleotides enhanced the sensitivity of human glioma cells to paclitaxel. A combination of paclitaxel with antisense c-Met oligodeoxynucleotides inhibited cell growth, induced apoptosis and induced c-Met protein expression in U251 and SHG44 human glioma cells more significantly than either paclitaxel or the oligodeoxynucleotides on their own (P<0.01). Thus, c-Met antisense oligodeoxynucleotides increase the sensitivity of human glioma cells to paclitaxel. Combined use of the two agents could be a novel and attractive strategy in human glioma treatment.

c-Met-targeted RNA interference inhibits growth and metastasis of glioma U251 cells in vitro.

Angiogenesis plays an essential role in tumor growth and metastasis and is a promising target for cancer therapy. c-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor (HGF), are critical in cellular proliferation, motility, invasion, and angiogenesis. The present study was designed to determine the role of c-Met in growth and metastasis of glioma U251 cells using RNA interference (RNAi) technology in vitro. We constructed three kinds of shRNA expression vectors aiming at the c-Met gene, then transfected them into glioma U251 cells by lipofectamine(TM) 2000. The level of c-Met mRNA was investigated by real-time polymerse chain reaction (RT-PCR). The protein expression of c-Met was observed by immunofluoresence staining and western blotting. U251 cell growth and adherence was detected by methyl thiazole tetrazolium assay. The apoptosis of U251 cells was examined with a flow cytometer. The adherence, invasion, and in vitro angiogenesis assays of U251 cells were done. We got three kinds of c-Met specific shRNA expression vectors which could efficiently inhibit the growth and metastasis of U251 cells and the expression of c-Met in U251 cells. RT-PCR, immunofluoresence staining and western blotting showed that inhibition rate for c-Met expression was up to 90%, 79% and 85%, respectively. The expression of c-Met can be inhibited by RNA interference in U251 cells, which can inhibit the growth and metastasis of U251 cell and induce cell apoptosis. These results indicate that RNAi of c-Met can be an effective antiangiogenic strategy for glioma.

Stabilization of hepatocyte growth factor mRNA by hypoxia-inducible factor 1.

Hypoxia regulates expression of hepatocyte growth factor (HGF) by increasing its transcription and by stabilizing its mRNA. Despite the pivotal role of hypoxia-inducible factor 1 (HIF-1) in transcriptional activation of hypoxia-responsive genes, it is not known whether HIF-1 mediates hypoxia-induced stabilization of HGF mRNA. We constructed adenoviral vectors expressing either the wild-type HIF-1alpha (Ad2/HIF-1alpha/FL), a constitutively stable hybrid form of HIF-1alpha (Ad2/HIF-1alpha/VP16), or no transgene (Ad2/CMVEV). In rat glioma (C6) cells, human glioma (U251) cells human cardiac, vascular smooth muscle, and endothelial cells, infection with Ad2/HIF-1alpha/VP16 or Ad2/HIF-1alpha/FL increased HGF expression at both the mRNA and protein levels. Under normoxic conditions, the half-life of HGF mRNA was 43 min in C6 and U251 cells. Hypoxia and Ad2/HIF-1alpha/VP16 increased the half-life of HGF mRNA to 3.2 and 2.8 h, respectively, while Ad2/CMVEV had no effect. These studies are the first to demonstrate that overexpression of HIF-1alpha increases HGF mRNA stability. Our results also suggest that stabilization of HGF mRNA by hypoxia is mediated, at least in part, by HIF-1.

c-Met antisense oligodeoxynucleotides as a novel therapeutic agent for glioma: in vitro and in vivo studies of uptake, effects, and toxicity.

BACKGROUND: c-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor, are critical in cellular proliferation, motility, and invasion and are known to be overexpressed in gliomas. The aim of our study was to investigate the uptake and effects of c-Met antisense oligodeoxynucleotides (ASODNs) on rat and human glioma cells in vitro and the uptake and toxicity of these nucleotides in rat carcinomatosis and brain tumor models. MATERIALS AND METHODS: The three human cell lines (U87, BT325, SHG44) and the C6 rat glioma cell line were cultured. To study the uptake of oligodeoxynucleotides (ODNs) by glioma cells in vitro, cultured glioma cells readily incorporated caroboxyfluorescein-5-succimidyl ester (FAM) labeled phosphorothioate oligodeoxynucleotides, as demonstrated by immunofluorescence microscopy and flow cytometry. To study the effect of ASODNs treatment on c-Met expression in vitro, Expression of c-Met was assessed by immunofluorescence microscopy and reverse transcriptase polymerase chain reaction (RT-PCR) analysis. For animal studies of ODNs toxicity and uptake, eight rats underwent placement of cisternal catheters, under general anesthesia. Four rats were given 24 mug FAM-labeled ASODNs while the others were given a saline control injection. After a 24 h observation period, rats were sacrificed by barbiturate overdose, and their brains were studied. RESULTS: For all cell lines, fluorescence was seen to increase with increasing ASODNs concentration. Cells treated in similar fashion were also analyzed by flow cytometry to graphically illustrate the differing fluorescence. Multiple glioma cell lines were tested, with similar results. c-Met ASODNs was found to be successfully incorporated from the media into cultured human glioma cells, even at concentrations as low as 2 muM. In addition, maintenance of the pH-dependent green fluorescence color, as seen by immunofluorescence microscopy and by using flow cytometry, indicated that the FAM was not contained within lysosomes. Immunofluorescence microscopy and RT-PCR analysis showed decreases in c-Met expression with oligodeoxynucleotides treatment. Uptake into tumor cells was also demonstrated in vivo, with no detectable toxicity at concentrations exceeding expected therapeutic levels. CONCLUSION: These data are encouraging for further study of c-Met antisense oligodeoxynucleotides as a therapeutic modality for glioma.

Hepatocyte growth factor production is stimulated by gangliosides and TGF-beta isoforms in human glioma cells.

Hepatocyte growth factor (HGF) is a pleiotrophic cytokine that stimulates motility and invasion of several cancer cell types and induces angiogenesis, which is known to be expressed in several malignancies including glioma. The effect of transforming growth factor-beta (TGF-beta) isoforrns as well as gangliosides on HGF production was investigated in human glioma cell lines. TGF-beta isoforms and gangliosides were found to differentially stimulate HGF production by these cells. The ganglioside GD3 enhanced this release to the greatest extent and the stimulation was more marked in a glioblastoma cell line than in the two other anaplastic astrocytoma cell lines. These results suggest that both TGF-betas and gangliosides may act as indirect angiogenic factors by stimulating HGF secretion.

In vitro and in vivo potentiating the cytotoxic effect of radiation on human U251 gliomas by the c-Met antisense oligodeoxynucleotides.

C-Met, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor (HGF), are critical in cellular proliferation, motility, and invasion, and are known to be overexpressed in gliomas, which are related to the repair of damaged DNA. In this study, we investigated both in vitro and in vivo whether inhibition of the c-Met gene by antisense oligonucleotides (ODNs) enhances the cytotoxic effect of radiation on human U251 gliomas. A volume of 100 nM of c-Met antisense ODNs inhibited the level of mRNA by more than 95% and reduced the protein expression by about 70%. Treatment of human U251 glioma cells with 100 nM of c-Met antisense ODNs significantly enhanced the radiation-induced cell kill compared to control cells, and cells treated with nonsense ODNs. When the glioma cells were implanted in the cisterna magna of nude mice followed by treatment with c-Met antisense ODNs, the survival time of the nude mice was markedly prolonged compared to that of the untreated group (P < 0.001, logrank test). In addition, the combination of antisense ODNs and irradiation extended the survival time of the glioma-bearing nude mice much longer than could be achieved with radiation alone (P < 0.0001, logrank test). These results suggest that inhibition of c-Met can be expected to serve as a novel potentiator for radiation therapy in human U251 gliomas.

[Experimental study of apoptosis and Fas antigen expression in craniocerebral trauma].

OBJECTIVE: To evaluate the change in Fas antigen expression and apoptosis of neurons, to provide an experimental evidence of loss of neurons in craniocerebral injury, and to provide experimental evidence for clarifying multi-approach of the lost neuron after damage. METHODS: Brain impact injury was reproduced in SD rat with a free falling impacting device. Using immunohistochemistry method the Fas protein expression was assessed and apoptotic cells were detected with electron microscopy. RESULTS: Apoptotic cells were found near the contused area, and Fas-positive cells appeared around the injured and hippocampus areas at about 4 hours, peaked at 24 hours after injury and then reduced in number. CONCLUSION: Apoptosis and necrosis are two forms of cell death in brain tissue following experimental brain contusion. Moreover, the results imply that the Fas-FasL pathway plays a pivotal role in the pathophysiology of post-traumatic neuronal apoptosis.

Effects of magnesium sulfate on traumatic brain edema in rats.

OBJECTIVE: To investigate the effects of magnesium sulfate on traumatic brain edema and explore its possible mechanism. METHODS: Forty-eight Sprague-Dawley (SD) rats were randomly divided into three groups: Control, Trauma and Treatment groups. In Treatment group, magnesium sulfate was intraperitoneally administered immediately after the induction of brain trauma. At 24 h after trauma, total tissue water content and Na(+), K(+), Ca(2+), Mg(2+) contents were measured. Permeability of blood-brain barrier (BBB) was assessed quantitatively by Evans Blue (EB) dye technique. The pathological changes were also studied. RESULTS: Water, Na(+), Ca(2+) and EB contents in Treatment group were significantly lower than those in Trauma group (P<0.05). Results of light microscopy and electron microscopy confirmed that magnesium sulfate can attenuate traumatic brain injury and relieve BBB injury. CONCLUSIONS: Treatment with MgSO4 in the early stage can attenuate traumatic brain edema and prevent BBB injury.