Overexpression of phosphatidylethanolamine-binding protein 4 (PEBP4) associates with recurrence of meningiomas.

BACKGROUND AND PURPOSE: Abnormal expression of phosphatidylethanolamine-binding protein 4 (PEBP4) has been identified in various types of malignant tumors. In the present study, we investigated the expression of PEBP4 in meningioma cases and examined whether PEBP4 expression was correlated with outcomes among these patients. MATERIALS AND METHODS: The expression levels of PEBP4 and Ki-67 in human meningioma tissues from 65 patients were evaluated by immunohistochemical staining. The correlation between PEBP4 immunoreactivity in meningioma samples and patients' clinical outcomes was examined using the Kruskal-Wallis correlation test. The prognostic value of PEBP4 expression in meningiomas patients also was investigated. RESULTS: Immunohistochemical analysis revealed up-regulated PEBP4 expression in both atypical and anaplastic meningiomas compared with classical meningiomas (13.38 ± 4.19% vs. 3.64 ± 2.04%, P < 0.001). PEBP4 immunoreactivity in meningioma samples was closely correlated with that for Ki-67 (Spearman r = 0.7922, P < 0.0001). PEBP4 expression was also associated with tumor differentiation grade and clinical recurrence (P < 0.05). Multivariate regression analysis showed with high PEBP4 expression was associated with a longer recurrence-free survival (hazard ratio=0.252, 95% confidence interval: 0.067-0.940, P = 0.040). CONCLUSION: PEBP4 may play an important role in the progression of meningioma, as high PEBP4 expression was associated with a higher pathological grade of meningioma. Moreover, PEBP4 expression may be a meaningful prognostic biomarker in meningioma.

Knockdown of PEBP4 inhibits human glioma cell growth and invasive potential via ERK1/2 signaling pathway.

Phosphatidylethanolamine (PE)-binding protein 4 (PEBP4) is an antiapoptotic protein that is aberrantly expressed in various malignancies. We previously demonstrated that PEBP4 expression is dramatically induced in human gliomas and positively correlated with tumor grade and patient survival. However, the function of PEBP4 in human glioma development and underlying mechanisms remain largely unknown. By stable lentiviral vector-mediated silencing of PEBP4, we examined the effects of PEBP4 knockdown on the growth, apoptosis, and invasion of U251 and U373 human glioma cell lines using MTT, Transwell, colony formation, and flow cytometric assays. We examined the in vivo role of PEBP4 in tumor growth by inoculation of BALB/c nu/nu male mice with PEBP4-deficient U251 and U373 cells. The expression of cell cycle- and apoptosis-related proteins was analyzed by Western blotting and immunostaining. Knockdown of PEBP4 significantly reduced the proliferation and invasion of human glioma cells while inducing cell apoptosis by altering the expression of cell cycle- and apoptosis-related proteins. Mechanistically, PEBP4 knockdown led to activation of the extracellular signal-regulated kinases 1/2 (ERK1/2) pathway, an effect that could be reversed by U0126, a selective inhibitor of MEK1/2 (upstream of ERK1/2), suggesting involvement of ERK1/2 signaling in the regulation of glioma development and progression by PEBP4. We identified PEBP4 as a novel regulator mediating human glioma cell proliferation, invasion, and apoptosis as well as tumor formation and growth. Therefore, PEBP4 may be a potential therapeutic target in human glioma treatment.

Increased expression of phosphatidylethanolamine-binding protein 4 (PEBP4) strongly associates with human gliomas grade.

Abnormal expression of phosphatidylethanolamine-binding protein 4 (PEBP4) has been found in various types of malignancies. However, the PEBP4 expression in human gliomas is still unclear. In this study, we aim to compare the expression of PEBP4 in tumor samples derived from 58 patients with different grades of gliomas with that in 5 non-neoplastic brain samples and to investigate the clinical significance of PEBP4 expression in gliomas. The mRNA and protein expressions of PEBP4 were measured by real-time quantitative polymerase chain reaction and western blot, respectively. The intracellular expressions of PEBP4 in samples were examined by immunohistochemistry. The association between PEBP4 expression and the clinicopathologic characteristics of gliomas patients were analyzed. Our results demonstrated that the mRNA and protein levels of PEBP4 were upregulated in gliomas tissues, especially in high-grade (World Health Organization Grades III and IV) gliomas, when compared to normal control (p < 0.01). Immunohistochemical analysis indicated that PEBP4 was highly expressed in 82.4% (28/34) of high-grade gliomas, when compared to 41.7% (10/24) of high expression in low-grade gliomas and 20.0% (1/5) in non-neoplastic brain samples (p = 0.001). Multivariate Cox regression analysis revealed that increased PEBP4 expression was an independent prognostic factor for gliomas. Patients with low level of PEBP4 had longer survival time compared to those with high PEBP4 expression (p = 0.003). These data indicate a clinical significance of PEBP4 for predicting the tumor grade and the prognosis in patients with gliomas.

SIRT3 Expression Decreases with Reactive Oxygen Species Generation in Rat Cortical Neurons during Early Brain Injury Induced by Experimental Subarachnoid Hemorrhage.

Sirtuin3 (SIRT3) is an important protein deacetylase which predominantly presents in mitochondria and exhibits broad bioactivities including regulating energy metabolism and counteracting inflammatory effect. Since inflammatory cascade was proved to be critical for pathological damage following subarachnoid hemorrhage (SAH), we investigated the overall expression and cell-specific distribution of SIRT3 in the cerebral cortex of Sprague-Dawley rats with experimental SAH induced by internal carotid perforation. Results suggested that SIRT3 was expressed abundantly in neurons and endothelia but rarely in gliocytes in normal cerebral cortex. After experimental SAH, mRNA and protein expressions of SIRT3 decreased significantly as early as 8 hours and dropped to the minimum value at 24 h after SAH. By contrast, SOD2 expression increased slowly as early as 12 hours after experimental SAH, rose up sharply at the following 12 hours, and then was maintained at a higher level. In conclusion, attenuated SIRT3 expression in cortical neurons was associated closely with enhanced reactive oxygen species generation and cellular apoptosis, implying that SIRT3 might play an important neuroprotective role during early brain injury following SAH.

Nicardipine in the treatment of aneurysmal subarachnoid haemorrhage: a meta-analysis of published data.

Nicardipine is a dihydropyridine-type Ca(2+) channel blocker with a powerful antihypertensive activity and a unique cerebrovascular profile. Recent studies have examined nicardipine for the treatment of patients with aneurysmal subarachnoid haemorrhage (SAH), but have shown inconsistent results. In the current study, a meta-analysis was performed to assess the clinical effectiveness of nicardipine in the prevention of cerebral vasospasm in patients who had suffered from aneurysmal SAH. Medline, EMBASE, and PubMed databases were searched for the controlled trials evaluating nicardipine for treating SAH after a ruptured aneurysm, without language restrictions. Moreover, a manual search of the bibliographies of relevant articles was also conducted. Two researchers of the present study independently performed the literature search and the data extraction. The meta-analyses were performed using the software RevMan 4.2.10 (provided by the Cochrane Collaboration, Oxford, UK). Five published manuscripts involving 1,154 patients were included in this meta-analysis. Nicardipine infusion reduced the risk of poor outcome (death, vegetative state, or dependency) and mortality, with an odds ratio (OR) of 0.58 [95 % confidence interval (CI) 0.37-0.90] and 0.45 (95 % CI 0.15-1.29), respectively. This meta-analysis suggests that nicardipine therapy reduces the likelihood of poor outcome and mortality in patients after aneurysmal SAH.

Therapeutic potential of peroxisome proliferator-activated receptor γ agonist rosiglitazone in cerebral vasospasm after a rat experimental subarachnoid hemorrhage model.

The pathogenesis of cerebral vasospasm is closely associated with inflammation and immune response in arterial walls. Recently, the authors proved the key role of Toll-like receptor (TLR)4 in the development of vasospasm in experimental subarachnoid hemorrhage (SAH) model. Because peroxisome proliferator-activated receptor (PPAR) gamma agonists are identified as effective inhibitors of TLR4 activation, we investigated the anti-inflammation properties of PPAR-gamma agonist rosiglitazone in basilar arteries in a rat experimental SAH model and evaluated the effects of rosiglitazone on vasospasm. Inflammatory responses in basilar arteries were assessed by immunohistochemical staining for intercellular molecule (ICAM)-1 and myeloperoxidase (MPO). Expression of TLR4 was determined by western blot analysis. The degree of cerebral vasospasm was evaluated by measuring the mean diameter and cross-sectional area of basilar arteries. Rosiglitazone suppressed the SAH-induced inflammatory responses in basilar arteries by inhibiting the TLR4 signalling. Furthermore, rosiglitazone could attenuate cerebral vasospasm following SAH. Therefore, we suggested that PPAR-gamma agonists may be potential therapeutic agents for cerebral vasospasm.

Potential role of Ras in cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits.

Previous studies have demonstrated that mitogen-activated protein kinase (MAPK) is involved in the pathogenesis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Ras, an upstream regulator of MAPK, may be activated following SAH. The aim of this study was to investigate the role of Ras in cerebral vasospasm in a rabbit model of SAH. We first investigated the time course of Ras and ERK1/2 activation in the basilar artery after SAH. Next, for the time point at which Ras was maximally activated, we assessed the effect of FTI-277 (a Ras farnesyltransferase inhibitor) on cerebral vasospasm. SAH was induced by injecting autologous blood into the cisterna magna on both day 0 and day 2. FTI-277 was injected into the cisterna magna every 24 hours, beginning 30 minutes after blood injection to the last day of the experiment. Elevated expression of Ras-GTP and phosphorylated ERK1/2 was detected in the basilar artery after SAH and expression peaked on day 3. FTI-277 administration resulted in lower Ras-GTP and phosphorylated ERK1/2 levels and markedly attenuated vasospasm in the basilar arteries relative to animals that did not receive FTI-277. Our results suggest that Ras protein is activated in the arterial wall after SAH and contributes to vasospasm development.

Preliminary study on the effect of trauma-induced secondary cellular hypoxia in brain injury.

Secondary cerebral hypoxia has recently been shown to play an important role in the outcome of patients suffering from traumatic brain injury (TBI). However, the precise mechanisms underlying secondary cerebral hypoxia are complex and interrelated. In this study, we investigate the effect of hypoxia within a rat model of trauma-induced late cerebral cortex injury. Using the hypoxia marker pimonidazole, we verified and isolated areas of the cortex that had suffered hypoxic damage. Using subsequent reverse-transcriptase PCR analyses, we found that the expressions of both transforming growth factor beta1 (TGF-beta1) and hypoxia-inducible factor-1alpha (HIF-1alpha) increased significantly under hypoxic conditions induced by TBI compared with uninjured control animals. In addition, the maximum mRNA expression of TGF-beta1 and HIF-1alpha was found at 3 days and 12h after TBI, respectively. Our data suggest that secondary cerebral hypoxia injury involves various cytokines including TGF-beta1 and HIF-1alpha. Furthermore, upon immunohistochemical analysis, both TGF-beta1 and HIF-1alpha expression were almost localized in the same types of cells by using immunohistochemical study. These results may have important implications in the understanding of trauma-induced secondary cerebral hypoxia injury.

Quantitative detection of the expression of mitochondrial cytochrome c oxidase subunits mRNA in the cerebral cortex after experimental traumatic brain injury.

Secondary brain damage plays a critical role in the outcome of patients with traumatic brain injury (TBI). The multiple mechanisms underlying secondary brain damage, including posttraumatic cerebral ischemia, glutamate excitotoxicity, oxidative stress, calcium overload and inflammation, are associated with increased mortality and morbidity after head injury. TBI is documented to have detrimental effects on mitochondria, such as alterations in glucose utilization and the depression of mitochondrial oxidative phosphorylation. Studies on mitochondrial metabolism have provided evidence for dysfunction of the cytochrome oxidase complex of the electron transport chain (complex IV) after TBI. A growing body of evidence indicates that cytochrome c oxidase is vital for mitochondrial oxidative phosphorylation. Therefore, this study aimed to detect the expression of cytochrome c oxidase (CO) mRNA in a rat weight-dropping trauma model and to clarify the differences between injured cortex (IC) and contralateral cortex (CC) after TBI. A total of forty-four rats were randomly assigned to 7 groups: control groups (n=4), sham-operated group (n=20), 6 h, 1 d, 3 d, 5 d and 7 d postinjury groups (n=4 for each group). The group consisted of sham-operated animals underwent parietal craniotomy without TBI. The rats in postinjury groups were subjected to TBI. The rats of control group were executed immediately without TBI or craniotomy after anesthesia. The brain-injured and sham-operated animals were killed on 6 h, 1 d, 3 d, 5 d and 7 d, respectively. Tissue sections from IC and CC were obtained and the expression of cytochrome c oxidase I, II, and III (CO I, II, III) mRNA, three mitochondrial encoded subunits of complex IV, were assessed by Real-time quantitative PCR. A reduction of CO I, II, and III mRNA expression was detected from IC and reduced to the lowest on 3 d. By contrast, the mRNA expression from CC suggested a slight elevation. The differences may indicate the degree of metabolic and physiologic dysfunction. Our results will better define the roles of gene expression and metabolic function in long-term prognosis and outcome after TBI. With a considerable understanding of post-injury mitochondrial dysfunction, therapeutic interventions targeted to the mitochondria may prevent secondary brain damage that leads to long-term cell death and neurobehavioral disability.