ATP1A1 Integrates AKT and ERK Signaling via Potential Interaction With Src to Promote Growth and Survival in Glioma Stem Cells.

Glioma stem cells (GSCs) have been considered to be responsible for treatment failure due to their self-renewal and limitless proliferative property. Recently, the Na+/K+-ATPase a1 (ATP1A1) subunit was described as a novel therapeutic target for gliomas. Interestingly, our previous proteomics study revealed that ATP1A1 is remarkably overexpressed in GSCs. In the current study, we investigated the role of ATP1A1 in regulating growth, survival, and tumorigenicity of primary human GSCs and the underlying molecular mechanism. We tested RNA and protein expression of ATP1A1 in glioma tissues and GSCs. In addition, we knocked down ATP1A1 in GSCs and assessed the effects thereof on growth, survival, and apoptosis. The role of ATP1A1 in signaling pathways was investigated in vitro. We found that the ATP1A1 expression level was associated with the grade of glioma. Knockdown of ATP1A1 in GSCs in vitro inhibited cell proliferation and survival, increased apoptosis, and halted cell-cycle progression at the G1 phase. Cell proliferation and survival were resumed upon rescue of ATP1A1 expression in ATP1A1-knockdown GSCs. The ERK1/2 and AKT pathways were inhibited through suppression of Src phosphorylation by ATP1A1 knockdown. Collectively, our findings suggest that ATP1A1 overexpression promotes GSC growth and proliferation by affecting Src phosphorylation to activate the ERK1/2 and AKT signaling pathways.

Splicing factor hnRNPA2B1 contributes to tumorigenic potential of breast cancer cells through STAT3 and ERK1/2 signaling pathway.

Increasing evidence has indicated that the splicing factor hnRNPA2B1 plays a direct role in cancer development, progression, gene expression, and signal transduction. Previous studies have shown that knocking down hnRNPA2B1 in breast cancer cells induces apoptosis, but the mechanism and other functions of hnRNPA2B1 in breast cancer are unknown. The goal of this study was to investigate the biological function, clinical significance, and mechanism of hnRNPA2B1 in breast cancer. The expression of hnRNPA2B1 in 92 breast cancer and adjacent normal tissue pairs was analyzed by immunohistochemical staining. Stable clones exhibiting knockdown of hnRNPA2B1 via small hairpin RNA expression were generated using RNA interference technology in breast cancer cell lines. The effects of hnRNPA2B1 on cell proliferation were examined by MTT and EdU assay, and cellular apoptosis and the cell cycle were examined by flow cytometry. A nude mouse xenograft model was established to elucidate the function of hnRNPA2B1 in tumorigenesis in vivo. The role of hnRNPA2B1 in signaling pathways was investigated in vitro. Our data revealed that hnRNPA2B1 was overexpressed in breast cancer tissue specimens and cell lines. Knockdown of hnRNPA2B1 reduced breast cancer cell proliferation, induced apoptosis, and prolonged the S phase of the cell cycle in vitro. In addition, hnRNPA2B1 knockdown suppressed subcutaneous tumorigenicity in vivo. On a molecular level, hnRNPA2B1 knockdown decreased signal transducer and activator of transcription 3 and extracellular-signal-regulated kinase 1/2 phosphorylation. We concluded that hnRNPA2B1 promotes the tumorigenic potential of breast cancer cells, MCF-7 and MDA-MB-231, through the extracellular-signal-regulated kinase 1/2 or signal transducer and activator of transcription 3 pathway, which may serve as a target for future therapies.

Astrocytes Regulate Angiogenesis Through the Jagged1-Mediated Notch1 Pathway After Status Epilepticus.

Vascular disruptions including blood-brain barrier breakdown and pathologic angiogenesis contribute to the development of epilepsy in normal brains. The Notch signaling pathway is activated in response to seizure activity, and its activation promotes seizures, although its exact role in angiogenesis is poorly understood. Here, we have examined the role of Notch signaling in angiogenesis in a kainic acid-induced mouse model of epilepsy. We show that following seizures, expression of the Notch ligand Jagged1 in the hippocampus is upregulated in astrocytes and levels of activated Notch1 are increased in endothelial cells. Using an in vitro model of angiogenesis, we provide evidence that brain endothelial tube formation is promoted in the presence of astrocytes. Isolated primary brain endothelial cells develop significantly longer vascular sprouts when cultured in the presence of astrocytes. Notch1 signaling is activated in brain endothelial cells cocultured with astrocytes, and astrocytic Jagged1 expression is required for angiogenic enhancement, as shown by the inhibitory effect of Jagged1 small interfering RNA (siRNA) expression in astrocytes on endothelial cell vascular sprouting in vitro. Therapies targeting the Jagged1/Notch1 signaling pathway may therefore be effective in limiting aberrant angiogenesis following status epilepticus.

Effects of hnRNP A2/B1 Knockdown on Inhibition of Glioblastoma Cell Invasion, Growth and Survival.

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) plays an important role in influence of pre-messenger RNA (pre-mRNA) processing and mRNA metabolism and transportation in cells. Increasing evidence indicates that hnRNP A2/B1 played an important role in development and progression of various human cancers. Forty cases of normal and human glioma tissue samples were analyzed using immunohistochemistry to reveal the expression of hnRNP A2/B1 protein in the samples. Then, knockdown of hnRNP A2/B1 expression induced by RNA interference (RNAi) method was used to analyze the role of hnRNP A2/B1 in glioblastoma cell viability, adhesion, migration, invasion, and chemoresistance for temozolomide (TMZ). The data showed that hnRNP A2/B1 protein was overexpressed in glioma tissue specimens and associated with advanced glioma grades. Knockdown of hnRNP A2/B1 could reduce glioblastoma cell viability, adhesion, migration, invasion, and chemoresistance for TMZ capacity, but induced tumor cells to apoptosis and reactive oxygen species (ROS) generation in glioma U251 and SHG44 cells. Molecularly, hnRNP A2/B1 knockdown reduced expression of phospho-STAT3 and MMP-2. Detection of hnRNP A2/B1 expression may be useful as a biomarker for prediction of glioma progression and knockdown of hnRNP A2/B1 expression as a novel strategy in future control of glioblastoma in clinic.

Overexpression of S100A9 in human glioma and in-vitro inhibition by aspirin.

Our previous work has shown that S100A9 promotes the growth of glioma cells. The aim of this study was to investigate S100A9 expression in glioma cells and to explore the potential of NSAIDs in the inhibition of S100A9. The levels of S100A9 were analyzed in five normal human brain tissues and 109 astrocytomas by immunohistochemical analysis. In addition, S100A9 levels were detected in normal human astrocytes, glioma cell lines, and six pairs of matched astrocytoma tissues by reverse transcription-PCR or western blotting analysis. After treatment with 4, 8, and 16 mmol/l aspirin, cell viability, early apoptosis rate, and S100A9 levels were quantified. Cell viability and the changes in S100A9 levels were also examined in glioma cells exposed to a cyclooxygenase-2 inhibitor, NS-398, alone and in combination with prostaglandin E2. We found that S100A9 was upregulated in astrocytomas and was significantly (P<0.05) correlated with histologic grades. S100A9 protein levels were also elevated in six astrocytomas compared with matched adjacent noncancerous tissues. Both S100A9 mRNA and protein levels were higher in glioma cell lines than in normal human astrocytes (P<0.05). Aspirin treatment inhibited cell proliferation and caused early apoptosis in glioma, coupled with reduced S100A9 levels. Treatment with NS-398 decreased cell growth and expression of S100A9 in glioma cells; these effects were partially reversed by exogenous prostaglandin E2. These results suggest overexpression of S100A9 in glioma cells. Aspirin may be a novel candidate for targeted prevention of S100A9 overexpression in glioma cells.

Comparative proteomics of glioma stem cells and differentiated tumor cells identifies S100A9 as a potential therapeutic target.

Recent studies have suggested the existence of a small subset of cancer cells called cancer stem cells (CSCs), which possess the ability to initiate malignancies, promote tumor formation, drive metastasis, and evade conventional chemotherapies. Elucidation of the specific signaling pathway and mechanism underlying the action of CSCs might improve the efficacy of cancer treatments. In this study, we analyzed differentially expressed proteins between glioma stem cells and differentiated tumor cells isolated from the human glioma cell line, U251, via iTRAQ-tagging combined with two dimensional liquid chromatography tandem MS analysis to identify proteins correlated with specific features of CSCs. Out of a total data set of 559 identified proteins, 29 proteins were up-regulated in the glioma stem cells when compared with the differentiated cells. Interestingly, The expression level of S100A9 was fivefold higher in glioma stem cells than differentiated cells. Similar results were also observed in glioma stem cells derived from other glioma cells. More importantly, knockdown of S100A9 by RNA interference suppressed the proliferation of glioma stem cell line and decreased the growth of xenograft tumors in vivo. Taken together, these results indicate that the tumorigenesis potential of CSCs arises from highly expressed S100A9.

The ABCG2 transporter is a key molecular determinant of the efficacy of sonodynamic therapy with Photofrin in glioma stem-like cells.

We aimed to investigate the role of the ABCG2 transporter in the efficacy of sonodynamic therapy (SDT) with Photofrin in the glioma stem-like cells (GSCs) isolated and cultured from U251 glioma cells. Immunocytochemistry and flow cytometry analyses showed that ABCG2 was overexpressed in GSCs, and the percentage of ABCG2-positive GSCs was approximately 100%. The effect of ABCG2 on Photofrin extrusion in the absence or presence of a specific inhibitor of ABCG2 (fumitremorgin C; FTC) was investigated by determining the intracellular concentration of Photofrin in GSCs incubated with 20µg/ml Photofrin. Extrusion of Photofrin by ABCG2 was inhibited by 10µM FTC, which significantly increased the intracellular Photofrin concentration (p<0.05) from 0.32±0.11µg/10(6) cells to 0.89±0.13µg/10(6) cells. MTT and TUNEL assays showed that the antitumor effect of SDT (incubation of GSCs with 20µg/ml Photofrin for 6h in the dark and ultrasonic activation at 1.0MHz and 0.5W/cm(2) for 2min) was significantly improved by FTC pretreatment (p<0.05). Moreover, incubation of GSCs with FTC significantly increased the relative production of ROS in response to SDT. The overexpression of ABCG2 in GSCs results in efflux of Photofrin, indicating that the antitumor effect of SDT with Photofrin may be reduced in GSCs overexpressing ABCG2. However, since FTC improves the efficacy of SDT in GSCs by inhibiting ABCG2-mediated efflux of Photofrin, FTC may be useful in SDT treatment of ABCG2-expressing cancer cells.

Neuroprotective effect of Cyclosporin A on the development of early brain injury in a subarachnoid hemorrhage model: a pilot study.

Cyclosporin A (CsA) has been demonstrated to be neuroprotective in ischemic and traumatic brain injuries by inhibiting mitochondrial permeability transition pore (mPTP) opening, thereby maintaining mitochondrial homeostasis and inhibiting pro-apoptotic protein release. The effects of CsA on early brain injury (EBI) after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of CsA on apoptotic signaling pathways and EBI after experimental SAH using four equal groups (n=36) of adult male SD rats, including the sham group, SAH+vehicle group, SAH+CsA2 group, and SAH+CsA10 group. The rat SAH model was induced by injection of 0.3ml non-heparinized arterial blood into the prechiasmatic cistern. In the SAH+CsA2 and SAH+CsA10 groups, a dose of 2mg/kg and 10mg/kg CsA was directly administered by intercarotid injection at 15min and again 24h after SAH induction. Cerebral tissue samples were extracted 48h after SAH. Increased expressions of Cytochrome C, apoptosis-inducing factor (AIF), and cleaved caspase-3 were observed in the cerebral cortex after SAH. Treatment with high dose (10mg/kg) CsA markedly decreased expressions of Cytochrome C, AIF, and cleaved caspase-3, and inhibited apoptosis pathways. Administration of CsA following SAH significantly ameliorated EBI, including cortical apoptosis, brain edema, blood-brain barrier (BBB) impairment, and neurobehavioral deficits. These findings suggest that early administration of CsA may ameliorate EBI and provide neuroprotection in the SAH model through potential mechanisms that include blockage of mPTP opening and inhibition of apoptotic cell death pathways.

Glioma stem-like cells are less susceptible than glioma cells to sonodynamic therapy with photofrin.

Despite remarkable progress in diagnosis and treatment, malignant glioma, a highly lethal cancer of the central nervous system, remains incurable. Although glioma stem-like cells (GSCs) represent a relatively small fraction of the cells in malignant glioma, they can proliferate and self renew extensively, being crucial for tumor recurrence. Cancer treatment by sonodynamic therapy (SDT) chiefly depends on antitumor effects of reactive oxygen species (ROS) generated from a sonosensitizer activated by ultrasound. Although SDT effectively kills glioma cells, its efficiency against GSCs is not established. We attempted to compare the susceptibility of GSCs to SDT, using Photofrin, a porphyrin-derivative photosensitizer, with that of glioma cells. Cell viability and apoptosis assays showed that SDT damaged both GSCs and U251 glioma cells, but GSCs were significantly less susceptible to SDT (p < 0.01). To elucidate the mechanism of the antitumor effects of SDT, we evaluated intracellular ROS production and Photofrin uptake: ROS production and Photofrin content were significantly lower (p < 0.01) in GSCs than in U251 glioma cells. Thus, cellular differences in sonosensitizer uptake and ROS production influence the antitumor effects of SDT. Furthermore, the resistance of GSCs may be caused by decreased sonosensitizer uptake due to ABCG2 overexpression.

Effective gene transfer into central nervous system following ultrasound-microbubbles-induced opening of the blood-brain barrier.

To investigate whether ultrasound-targeted microbubble destruction (UTMD) could transfer gene into central nervous system (CNS) following blood-brain barrier disruption (BBBD), DNA-loaded microbubbles were infused into the mice intravenously following ultrasonic exposure. Opening of the BBB, changes of mRNA and expression of enhanced green fluorescent protein (EGFP), and safety evaluation were measured. By UTMD, EGFP were substantially expressed in the cytoplasm of the neurons at the sonicated area with minor erythrocytes extravasation and the mRNA and expression of EGFP were markedly enhanced by about 15-fold and 10-fold, respectively, than that with US alone (p < 0.01). No EGFP was detected in the mice treated with DNA-loaded microbubbles or plasmid alone. The gene expression reached a climax at 48 h, gradually reduced to a much lower level thereafter. These results demonstrated UTMD could effectively enhance exogenous gene delivery and expression in CNS following BBBD, and this technique may provide a new method for CNS gene therapy.

The role of caveolin-1 in blood-brain barrier disruption induced by focused ultrasound combined with microbubbles.

This research was designed to determine whether disrupting the blood-brain barrier (BBB) in rats by applying focused ultrasound (FUS) combined with microbubbles induced changes in the density of caveolae and/or the expression of the structural protein caveolin-1. To this end, two approaches were utilized. First, using enhanced magnetic resonance imaging, characteristics of BBB disruption induced by our specific FUS parameters and dose of microbubble were recorded, and the time after treatment when the BBB was the most permeable was determined. Second, rats were treated with FUS or microbubbles alone, both or neither, and a combination of Evans blue (EB) BBB permeability assays, streptavidin-peroxidase (SP) immunohistochemistry, western blot, and transmission electron microscopy (TEM) was employed to detect any changes in caveolae density and caveolin-1 expression at the previously determined time point when the BBB was the most permeable. The first set of studies revealed that our specific FUS parameters and dose of microbubbles were able to induce a transient, targeted, and reversible BBB opening in rats, and that the BBB was the most permeable 1 h after treatment with FUS and microbubbles. In the second set of experiments, the results of the SP immunohistochemistry, western blot, and TEM, taken together, revealed that caveolae and caveolin-1 were primarily localized in the brain microvascular endothelial cells of all of the rats regardless of treatment, and that caveolin-1 expression was highest in the rats treated with both FUS and microbubbles. In summary, treatment with FUS, in combination with a dose of microbubbles, can enhance BBB permeability through a caveolae-mediated transcellular approach by upregulating the expression level of caveolin-1 and, consequently, the amount of caveolae. This caveolin-1-mediated transcellular transport pathway may cooperate with other transport pathways to induce opening of the BBB. This research sheds light on the mechanism of a transient, targeted, and reversible opening of the BBB induced by FUS combined with microbubbles.

Anatomical relationship between cranial surface landmarks and venous sinus in posterior cranial fossa using CT angiography.

PURPOSE: The purpose of this study was to determine the reliability of applying conventional anatomical landmarks to locate venous sinus in posterior fossa using subtraction computed tomography angiography (CTA) technique. METHODS: We retrospectively reconstructed transverse sinus (TS), sigmoid sinus (SS), and cranial imaging from 100 patients undergoing head CTA examination. Subtraction CTA data was merged with nonenhanced data and then cranium transparency was adjusted to 50% on three-dimensional volume rendering, indicating the anatomical relationship between surface landmarks of cranium and confluens sinuum, TS, and SS. RESULTS: CTA technique precisely displayed the anatomical relations between venous sinus in posterior fossa and cranial surface landmarks. The asterion was located directly over the transverse-sigmoid sinus junction (TSST) in 81% cases, inferior to TSST in 15%, and superior to TSST in 4%, mainly distributing on the TS side of TSST, namely the distal-end of TS. Superior nuchal line had complex relation with TS and the line drawn from the zygoma root to the inion (LZI), but failed to represent the location of TS and the trend of LZI. In proximal-end of TS, majority of LZI overlapped with TS line. However, most LZI was gradually positioned below TS line as TS moved outwards. Almost half of line drawn from the squamosal-parietomastoid suture junction to the inion and line drawn from the asterion to the inion shared the same trend with TS. CONCLUSION: Subtraction CTA merged into nonenhanced cranial bone with 50% skull transparency provides a feasible method to identify the anatomical relation between venous sinus and surface landmarks of cranium, which is significantly varied among individuals, so it is not accurate to determine venous sinus in posterior fossa merely using surface landmarks.

Targeted gene delivery to the mouse brain by MRI-guided focused ultrasound-induced blood-brain barrier disruption.

This study aimed to investigate the feasibility of targeted gene transfer into central nervous system (CNS) by MRI-guided focused ultrasound-induced blood-brain barrier (BBB) disruption. Before each sonication, T2-weighted images were obtained to select the target region. Followed by injecting DNA-loaded microbubbles into the tail vein, sonication was performed. The state of local BBB, distribution of plasmid DNA through the opened BBB, the ultrastructural changes of neurons and BDNF expression were detected. The results showed that MRI-guided focused ultrasound (FUS) could accomplish noninvasive, transient, and local BBB disruption, at 1h after sonication, plasmid DNA across the opened BBB had been internalized into the neurons presenting heterogeneous distribution and numerous transparent vesicles were observed in the cytoplasm of the neurons at the sonicated region, suggesting vesicle-mediated endocytosis. At 48 h after sonication, the expressions of exogenous gene pBDNF-EGFP were observed in the cytoplasm of some neurons, and BDNF expressions were markedly enhanced by the combination of ultrasound and pBDNF-EGFP-loaded microbubbles about 20-fold than that of the control group (P<0.01). The method by using MRI-guided FUS to induce the local BBB disruption could accomplish effective targeted exogenous gene transfer in CNS. This technique may provide a new option for the treatment of various CNS diseases.