CircMTA1 promotes glioblastoma angiogenesis by encoding MTA1-134aa

Glioblastoma multiforme (GBM) is the most malignant brain tumor with rapid angiogenesis. How to inhibit GBM angiogenesis is a key problem to be solved. To explore the targets of inhibiting GBM angiogenesis, this study confirmed that the expression of circMTA1 (hsa_circ_0033614) was significantly upregulated in human brain microvascular endothelial cells exposed to glioma cell-conditioned medium (GECs). The expression of circMTA1 in the cytoplasm was significantly higher than that in the nucleus. Upregulated circMTA1 in GECs can promote cell proliferation, migration, and tube formation. Further exploration of the circularization mechanism of circMTA1 confirmed that KHDRBS1 protein can bind to the upstream and downstream flanking sequences of circMTA1 and promote circMTA1 biogenesis by coordinating Alu element pairing. KHDRBS1 upregulated the proliferation, migration, and tube formation of GECs by promoting the biogenesis of circMTA1. CircMTA1 can encode the protein MTA1-134aa by internal ribosome entry site sequence-mediated translation mechanism, and promote the proliferation, migration, and tube formation of GECs through the encoded MTA1-134aa. This study provides a new target for inhibiting angiogenesis in brain GBM and a new strategy for improving the therapeutic efficacy of GBM.

[Correlation between cerebral oxygen saturation monitored by near-infrared spectroscopy during operation and risk of stroke after acute type A aortic dissection surgery]

Objective: Near-infrared spectroscopy (NIRS) is widely used for intraoperative cerebral oxygen saturation monitoring in patients with acute type A aortic dissection. This study aimed to investigate the correlation between NIRS-derived oxygen saturation and risk of postoperative stroke. Methods: This study included 193 patients with acute type A aortic dissection undergoing emergency surgery and elective unilateral cerebral perfusion via the right axillary artery at the Department of Cardiothoracic Surgery, Nanjing Drum Tower Hospital, Nanjing, China, from 2018 to 2020. NIRS was used for intraoperative cerebral oxygen saturation monitoring, and the basal values and the lowest values of cerebral oxygen saturation during deep hypothermic circulatory arrest (DHCA) were recorded. The patients were divided into no-stroke group (n=178, 92.2%) and stroke group (n=15, 7.8%) according to the absence or presence of postoperative stroke. The differences in preoperative, operative and postoperative clinical differences between the two groups were compared, and the relationship between the lowest cerebral oxygen saturation value and the change in cerebral oxygen saturation value ((base-lowest)/basal) and postoperative stroke were analyzed. Results: The proportion of preoperative atrial fibrillation (6.7% vs. 0.6%, P=0.026), and the proportion of preoperative hypotension (26.7% vs. 9.0%, P=0.031) were significantly higher in the stroke group than no-stroke group. There were no differences in the surgical approach between the two groups. Cardiopulmonary bypass (CPB) time ((256.1±84.8) h vs.(217.8±58.4) h, P=0.020), postoperative mechanical ventilation time ((139.3±172.8) h vs. (35.6±45.6) h, P<0.001) were significantly longer in stroke group as compared to no-stroke group. Incidence of postoperative tracheotomy (20.0% vs. 1.1%, P<0.001), acute kidney injury (73.3% vs. 30.3%, P=0.001) and continuous renal replacement therapy (46.7% vs. 11.8%, P<0.001) as well as mortality (20.0% vs. 5.1%, P=0.022) were significantly higher in the stroke group than in non-stroke group. There was no significant difference in the basal NIRS value and the lowest NIRS value during DHCA between the two groups. Patients in the stroke group had a significantly greater intraoperative change rate of right NIRS as compared to no-stroke group (15.2%±15.7% vs. 9.2%±7.0%, P=0.006). Conclusions: NIRS is valuable for monitoring cerebral oxygen saturation during acute type A aortic dissection surgery, and the rate change of NIRS during operation correlates significantly with postoperative stroke.

Ghrelin alleviates 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y cells

Ghrelin is a neuropeptide that has various physiological functions and has been demonstrated to be neuroprotective in a number of neurological disease models. However, the underlying mechanisms of ghrelin in Parkinson’s disease remain largely unexplored. The current study aimed to study the effects of ghrelin in a 6-hydroxydopamine (6-OHDA)-induced Parkinson’s disease model and evaluate the potential underlying mechanisms. In the present study, we treated an SH-SY5Y cell model with 6-OHDA, and observed that pretreatment with different concentrations of ghrelin (1, 10, and 100 nM) for 30 minutes relieved the neurotoxic effects of 6-OHDA, as revealed by Cell Counting Kit-8 and Annexin V/propidium iodide (PI) apoptosis assays. Reverse transcription quantitative polymerase chain reaction and western blot assay results demonstrated that 6-OHDA treatment upregulated α-synuclein and lincRNA-p21 and downregulated TG-interacting factor 1 (TGIF1), which was predicted as a potential transcription regulator of the gene encoding α-synuclein (SNCA). Ghrelin pretreatment was able to reverse the trends caused by 6-OHDA. The Annexin V/PI apoptosis assay results revealed that inhibiting either α-synuclein or lincRNA-p21 expression with small interfering RNA (siRNA) relieved 6-OHDA-induced cell apoptosis. Furthermore, inhibiting lincRNA-p21 also partially upregulated TGIF1. By retrieving information from a bioinformatics database and performing both double luciferase and RNA immunoprecipitation assays, we found that lincRNA-p21 and TGIF1 were able to form a double-stranded RNA-binding protein Staufen homolog 1 (STAU1) binding site and further activate the STAU1-mediated mRNA decay pathway. In addition, TGIF1 was able to transcriptionally regulate α-synuclein expression by binding to the promoter of SNCA. The Annexin V/PI apoptosis assay results showed that either knockdown of TGIF1 or overexpression of lincRNA-p21 notably abolished the neuroprotective effects of ghrelin against 6-OHDA-induced neurotoxicity. Collectively, these findings suggest that ghrelin exerts neuroprotective effects against 6-OHDA-induced neurotoxicity via the lincRNA-p21/TGIF1/α-synuclein pathway.

A Comparison of the Effectiveness of Online Instructional Strategies Optimized With Smart Interactive Tools Versus Traditional Teaching for Postgraduate Students

To solve the problem that lack of interaction in online courses affects motivation and effectiveness of students' learning, smart interactive tools were introduced into the online Neurobiology course. This study aimed to evaluate the students' satisfaction with online teaching mode and assess the academically higher and lower performing students' learning effectiveness in the online course optimized with smart interactive tools compared to face-to-face learning. Descriptive statistics and independent t-tests were used to describe student samples and determine the differences in students' satisfaction and performance. Reflections of students' satisfaction revealed that about 65.8% were satisfied with the learning involvement and about 60.5% were satisfied with the class interaction. Almost two-thirds of the class agreed that the smart interactive tools applied in the online course could help them attain their learning goals better. Among all the smart interactive functions, the class quiz was the most effective one in helping students grasp the main points of the course. No significant differences were found between the two teaching modes in the overall and academically higher or lower performing students' final exam average scores. Compared to each band score of such two teaching modes, no one failed to pass the final exam in the online course, however, three lower-performing students who were taught in the traditional course failed. This study suggested that optimized online teaching with smart interactive tools could produce the same learning effectiveness for the academically lower-performing students as for the higher-performing students. Meanwhile, the instructors could know the learning status in which each student was and perform personalized guidance and improve exam passing rate accordingly.

Long Non-coding RNA TUSC7, a Target of miR-23b, Plays Tumor-Suppressing Roles in Human Gliomas

Tumour suppressor candidate 7 (TUSC7) is a novel tumor suppressor gene generating long non-coding RNA (lncRNAs) in several types of human cancers. The expression and function of TUSC7 in human brain glioma has yet to be elucidated. In this study, TUSC7 was poorly expressed in tissues and cell lines of glioma, and the lower expression was correlated with glioma of the worse histological grade. Moreover, TUSC7 is a prognostic biomarker of glioma patients. Up-regulation of TUSC7 suppressed cellular proliferation and invasion of glioma cells, and accelerated cellular apoptosis. Bioinformatics analysis showed that TUSC7 specifically binds to miR-23b. MiR-23b was up-regulated in glioma and negatively correlated with the expression of TUSC7. The miR-23b expression was inhibited remarkably by the upregulation of TUSC7 and the reciprocal inhibition was determined between TUSC7 and miR-23b.RNA pull-down and luciferase reporter assays were used to validate the sequence-specific correlation between miR-23b and TUSC7. TUSC7 inhibited the proliferation, migration and invasion of glioma cells and promoted cellular apoptosis largely bypassing miR-23b. We conclude that the lncRNA TUSC7 acted as a tumor suppressor gene negatively regulated by miR-23b, suggesting a novel therapeutic strategy against gliomas.

NS1619 regulates the expression of caveolin-1 protein in a time-dependent manner via ROS/PI3K/PKB/FoxO1 signaling pathway in brain tumor microvascular endothelial cells

NS1619, a calcium-activated potassium channel (Kca channel) activator, can selectively and time-dependently accelerate the formation of transport vesicles in both the brain tumor capillary endothelium and tumor cells within 15min of treatment and then increase the permeability of the blood-brain tumor barrier (BTB). However, the mechanism involved is still under investigation. Using a rat brain glioma (C6) model, the expression of caveolin-1, FoxO1 and p-FoxO1 protein were examined at different time points after intracarotid infusion of NS1619 at a dose of 30μg/kg/min. Internalization of Cholera toxin subunit (CTB) labeled fluorescently was monitored by flow cytometry. The expression of caveolin-1 and FoxO1 protein at tumor microvessels was enhanced and caveolae-mediated CTB endocytosis was increased by NS1619 infusion for 15min. Compared with the 15min group, the expression of caveolin-1 protein was significantly decreased and the level of phosphorylation of FoxO1 was significantly increased in the NS1619 2h group. In addition, inhibitors of reactive oxygen species (ROS) or PI3K or PKB significantly attenuated the level of FoxO1 phosphorylation and also increased the expression of caveolin-1 protein in Human Brain Microvascular Endothelial Cells (HBMECs) cocultured with human glioma cells (U87) 2h after NS1619 treatment. This led to the conclusion that NS1619-mediated transport vesicle increase is, at least partly, related to the ROS/PI3K/PKB/FoxO1 signaling pathway.

DT(270-326) , a Truncated Diphtheria Toxin, Increases Blood-Tumor Barrier Permeability by Upregulating the Expression of Caveolin-1

AIM

The nontoxic mutant of diphtheria toxin (DT) has been demonstrated to act as a receptor-specific carrier protein to delivery drug into brain. Recent research showed that the truncated "receptorless" DT was still capable of being internalized into cells. This study investigated the effects and potential mechanisms of DT(270-326) , a truncated "receptorless" DT, on the permeability of the blood-tumor barrier (BTB).

METHODS

BTB and GECs were subjected to DT(270-326) treatment. HRP flux assays, immunofluorescent, co-immunoprecipitation, Western blot, CCK-8, and Flow cytometry analysis were used to evaluate the effects of DT(270-326) administration.

RESULTS

Our results revealed that 5 μM of DT(270-326) significantly increased the permeability of BTBin vitro, which reached its peak at 6 h. The permeability was reduced by pretreatment with filipinIII. DT(270-326) co-localized and interacted with caveolin-1 via its caveolin-binding motif. The mRNA and protein expression levels of caveolin-1 were identical with the changes of BTB permeability. The upregulated expression of caveolin-1 was associated with Src kinase-dependent tyrosine phosphorylation of caveolin-1, which subsequently induced phosphorylation and inactivation of the transcription factor Egr-1. The combination of DT(270-326) with doxorubicin significantly enhanced the loss of cell viability and apoptosis of U87 glioma cells in contrast to doxorubicin alone.

CONCLUSIONS

DT(270-326) might provide a novel strategy to increase the delivery of macromolecular therapeutic agents across the BTB.

MiRNA-200b Regulates RMP7-Induced Increases in Blood-Tumor Barrier Permeability by Targeting RhoA and ROCKII

The primary goals of this study were to investigate the potential roles of miR-200b in regulating RMP7-induced increases in blood-tumor barrier (BTB) permeability and some of the possible molecular mechanisms associated with this effect. Microarray analysis revealed 34 significantly deregulated miRNAs including miR-200b in the BTB as induced by RMP7 and 8 significantly up-regulated miRNAs in the BTB by RMP7. RMP7 induced tight junction (TJ) opening of the BTB, thereby increasing BTB permeability. Associated with this effect of RMP7 was a decrease in miR-200b expression within the human cerebral microvascular endothelial cells line hCMEC/D3 (ECs) of the BTB. Overexpression of miR-200b inhibited endothelial leakage and restored normal transendothelial electric resistance values. A simultaneous shift in occludin and claudin-5 distributions from insoluble to soluble fractions were observed to be significantly reduced. In addition, overexpression of miR-200b inhibited the relocation of occludin and claudin-5 from cellular borders into the cytoplasm as well as the production of stress fiber formation in GECs (ECs with U87 glioma cells co-culturing) of the BTB. MiR-200b silencing produced opposite results as that obtained from that of the miR-200b overexpression group. Overexpression of miR-200b was also associated with a down-regulation in RhoA and ROCKII expression, concomitant with a decrease in BTB permeability. Again, results which were opposite to that obtained with the miR-200b silencing group. We further found that miR-200b regulated BTB permeability by directly targeting RhoA and ROCKII. Collectively, these results suggest that miR-200b's contribution to the RMP7-induced increase in BTB permeability was associated with stress fiber formation and TJ disassembly as achieved by directly targeting RhoA and ROCKII.

miR-128 regulates the apoptosis and proliferation of glioma cells by targeting RhoE

In this study, we investigate whether miR-128 is capable of regulating the apoptosis and proliferation of human U251 glioma cells by downregulating RhoE. The expression of miR-128 was assessed by quantitative polymerase chain reaction in normal brain tissue and glioma samples. A significant downregulation of the expression of miR-128 was detected in glioma in contrast to normal brain tissue. Following the transfection of pre-miR-128 and anti-miR-128 into U251 cells, the high expression of miR-128 could inhibit proliferation and induce apoptosis in U251 cells, and those effects could be restored by miR-128 knockdown. To analyze the regulation mechanism of miR-128, TargetScan, miRanda and PicTar were used to ascertain whether RhoE was a potential target gene. Next, luciferase activity assay and western blot analysis confirmed that RhoE was a direct and specific target gene of miR-128. The advanced effects of pre-miR-128 on the apoptosis and proliferation of U251 cells were reversed by the upregulation of RhoE expression. In summary, aberrantly expressed miR-128 regulates apoptosis and proliferation in human glioma U251 cells partly by directly targeting RhoE. This finding may offer a new potential therapeutic strategy for the treatment of glioma.

Influence of the MACC1 gene on sensitivity to chemotherapy in human U251 glioblastoma cells

BACKGROUND

This study was conducted to determine the influence of MACC1 expression on chemotherapy sensitivity in human U251 glioblastoma cells.

MATERIALS AND METHODS

Expression of the MACC1 gene in 49 cases of human brain glioma was determined by quantitative real-time PCR. Silencing effects of RNA interference on MACC1 was detected by Western-blotting. Flow cytometry methods and methyl thiazolyl tetrazolium assay (MTT) were used to determine the apoptosis and growth inhibitory rates of the U251 cells with MACC1 silencing. before and after treatment with cisplatin (DDP).

RESULTS

MACC1 mRNA in gliomas was up-regulated remarkably, to 158.8% of that in peri-cancerous tissues (P<0.05). The siRNA-MACC1 could inhibit the expression of MACC1 protein significantly (p<0.05), associated with an increase in apoptosis rate from 2.57% to 5.39% in U251 cells and elevation of the growth inhibitory rate from 1.5% to 17.8% (p<0.05 for both). After treatment with DDP at various concentrations (1, 3, 5μg/ml), compared with control U251 cells, the apoptosis rate of MACC1-silenced U251 cells rose from 8.41%, 13.2% and 19.5% to 12.8%, 17.8% and 25.8%; the growth inhibitory rate increased from 16.2%, 19.3% and 24.5% to 23.7%, 28.4% and 36.3%.

CONCLUSIONS

There is a notable relationship between over-expression of MACC1 and the characteristics of glioma cells. Silencing of MACC1 was found to enhance the apoptosis and growth inhibitory rates of U251 glioma cells, and thereby increase their sensitivity to DDP chemotherapy.

Shikonin Inhibits the Migration and Invasion of Human Glioblastoma Cells by Targeting Phosphorylated β-Catenin and Phosphorylated PI3K/Akt: A Potential Mechanism for the Anti-Glioma Efficacy of a Traditional Chinese Herbal Medicine

Shikonin is an anthraquinone derivative extracted from the root of lithospermum. Shikonin is traditionally used in the treatment of inflammatory and infectious diseases such as hepatitis. Shikonin also inhibits proliferation and induces apoptosis in various tumors. However, the effect of shikonin on gliomas has not been fully elucidated. In the present study, we aimed to investigate the effects of shikonin on the migration and invasion of human glioblastoma cells as well as the underlying mechanisms. U87 and U251 human glioblastoma cells were treated with shikonin at 2.5, 5, and 7.5 μmol/L and cell viability, migration and invasiveness were assessed with CCK8, scratch wound healing, in vitro Transwell migration, and invasion assays. The expression and activity of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) and the expression of phosphorylated β-catenin (p-β-catenin) and phosphorylated PI3K/Akt were also checked. Results showed that shikonin significantly inhibited the cell proliferation, migration, invasion, and expression of MMP-2 and MMP-9 in U87 and U251 cells. The expression of p-β-catenin showed contrary trends in two cell lines. It was significantly inhibited in U87 cells and promoted in U251 cells. Results in this work indicated that shikonin displayed an inhibitory effect on the migration and invasion of glioma cells by inhibiting the expression and activity of MMP-2 and -9. In addition, shikonin also inhibited the expression of p-PI3K and p-Akt to attenuate cell migration and invasion and MMP-2 and MMP-9 expression in both cell lines, which could be reversed by the PI3K/Akt pathway agonist, insulin-like growth factor-1 (IGF-1).

Effect of caveolin-1 on the expression of tight junction-associated proteins in rat glioma-derived microvascular endothelial cells

Caveolin-1 affects the permeability of blood-tumor barrier (BTB) by regulating the expression of tight junction-associated proteins. However, the effect is still controversial. In the present work, we studied the regulative effect of caveolin-1 on the expression of tight junction-associated proteins and BTB via directly silencing and overexpressing of caveolin-1 by recombinant adenovirus transduction of glioma-derived microvascular endothelial cells in rat brain. The results show that the caveolin-1 downregulation resulted in decreased expression of tight junction-associated proteins, opening of tight junctions, and increasing the permeability of BTB, whereas the overexpression of caveolin-1 presented the opposite effects. Therefore, we conclude that caveolin-1 regulates the expression of tight junction-associated proteins in a positive manner, which further plays a role in the regulation of BTB permeability. This finding provides a novel therapeutic target for selectively opening of BTB.

Enhanced antitumor effect of shikonin by inhibiting Endoplasmic Reticulum Stress via JNK/c-Jun pathway in human glioblastoma stem cells

Though previous study demonstrated that shikonin could exert its antitumor activity by inducing apoptosis and necrosis, the pro-survival mechanisms involved in its antitumor process are still little to know. In the present study, for the first time, we found a protective mechanism was simultaneously activated which caused the reduced sensitivity of glioblastoma stem cells (GSCs) to the cytotoxicity of shikonin. Reduced active caspase-9 expression and enhanced mitochondrial membrane potential (MMP) were intriguingly observed within 24 h treatment by shikonin in GSCs. Further investigation identified that Endoplasmic Reticulum Stress (ERS) was involved in its antitumor process, which compromised the cytotoxicity of shikonin toward GSCs. Inhibiting ERS by 4-phenylbutyric acid (4-PBA) markedly enhanced the cytotoxicity of shikonin in GSCs. The consistent result was simultaneously observed in the GSCs-xenografted mice. Furthermore, our results identified that JNK/c-Jun pathway was involved in the antitumor process of shikonin, providing a mechanism by which ERS reduced the cytotoxicity of shikonin toward GSCs. Altogether, the novel observation in the present study identified that inhibiting ERS would be an attractive new approach to enhance the therapeutic potency of shikonin toward GSCs.

Overexpression of miR-18a negatively regulates myocyte enhancer factor 2D to increase the permeability of the blood-tumor barrier via Krüppel-like factor 4-mediated downregulation of zonula occluden-1, claudin-5, and occludin

miR-18a represses angiogenesis and tumor evasion by weakening vascular endothelial growth factor and transforming growth factor-β signaling to prolong the survival of glioma patients, although it is thought to be an oncogene. This study investigates the potential effects of miR-18a on the permeability of the blood-tumor barrier (BTB) and its possible molecular mechanisms. An in vitro BTB model was successfully established. The endogenous expression of miR-18a in glioma vascular endothelial cells (GECs) was significantly lower than that in normal vascular ECs, and the overexpression of miR-18a significantly increased the permeability of the BTB as well as downregulating the mRNA and protein expressions of tight junction-related proteins zonula occluden-1 (ZO-1), claudin-5, and occludin in GECs. Dual luciferase reporter assays revealed that miR-18a bound to the 3'-untranslated region (3'UTR) of myocyte enhancer factor 2D (MEF2D). The overexpression of both miR-18a and MEF2D with the 3'UTR significantly weakened the effect caused by miR-18a of decreasing the mRNA and protein expressions of ZO-1, claudin-5 and occludin and of increasing the permeability of the BTB. Chromatin immunoprecipitation showed that MEF2D could directly bind to KLF4 promoter. This study shows that miR-18a targets and negatively regulates MEF2D, which further regulates tight junction-related proteins ZO-1, claudin-5, and occludin through transactivation of KLF4 and, finally, changes the permeability of the BTB. MiR-18a should garner growing attention because it might serve as a potential target in opening the BTB and providing a new strategy for the treatment of gliomas.

CRM197 in Combination With shRNA Interference of VCAM-1 Displays Enhanced Inhibitory Effects on Human Glioblastoma Cells

CRM197 is a naturally nontoxic diphtheria toxin mutant that binds and inhibits heparin-binding epidermal growth factor-like growth factor. CRM197 serves as carrier protein for vaccine and other therapeutic agents. CRM197 also inhibits the growth, migration, invasion, and induces apoptosis in various tumors. Vascular cell adhesion molecule-1 (VCAM-1) is an important cell surface adhesion molecule associated with malignancy of gliomas. In this work, we aimed to investigate the role and mechanism of CRM197 combined with shRNA interference of VCAM-1 (shRNA-VCAM-1) on the migration, invasion, and apoptosis of glioblastoma cells. U87 and U251 human glioblastoma cells were treated with CRM197 (10 µg/ml) and shRNA interfering technology was employed to silence VCAM-1 expression. Cell viability, migration, invasiveness, and apoptosis were assessed with CCK8, Transwell and Annexin V-PE/7-AAD staining. Activation of cleaved caspase-3, 8, and 9, activity of matrix metalloproteinase-2/9 (MMP-2/9), and expression of phosphorylated Akt (p-Akt) were also checked. Results showed that CRM197 and shRNA-VCAM-1 not only significantly inhibited the cell proliferation, migration, invasion, but also promoted the apoptosis of U87 and U251 cells. Combined treatment of both displayed enhanced inhibitory effects on the malignant biological behavior of glioma cells. The activation of cleaved caspase-3, 8, 9 was promoted, activity of MMP-2 and MMP-9 and expression of p-Akt were inhibited significantly by the treatment of CRM197 and shRNA-VCAM-1 alone or in combination, indicating that the combination of CRM197 with shRNA-VCAM-1 additively inhibited the malignant behavior of human glioblastoma cells via activating caspase-3, 8, 9 as well as inhibiting MMP-2, MMP-9, and Akt pathway.

MiR-34a regulates blood-tumor barrier function by targeting protein kinase Cε

It is shown for the first time that overexpression of miR-34a increases blood–tumor barrier permeability by targeting PKCε, which is activated by p-PKCε and directly regulates the expression of tight junction–related proteins.

MicroRNA-34a (miR-34a) functions to regulate protein expression at the posttranscriptional level by binding the 3′ UTR of target genes and regulates functions of vascular endothelial cells. However, the role of miR-34a in regulating blood–tumor barrier (BTB) permeability remains unknown. In this study, we show that miR-34a overexpression leads to significantly increased permeability of BTB, whereas miR-34a silencing reduces the permeability of the BTB. In addition, miR-34a overexpression significantly down-regulates the expression and distribution of tight junction–related proteins in glioma endothelial cells (GECs), paralleled by protein kinase Cε (PKCε) reduction. Moreover, luciferase reporter gene analysis shows that PKCε is the target gene of miR-34a. We also show that cotransfection of miR-34a and PKCε inversely coregulates BTB permeability and protein expression levels of tight junction–related proteins. Pretreatment of ψεRACK, a PKCε-specific activator, decreases BTB permeability in miR-34a–overexpressed GECs and up-regulates expression levels of tight junction proteins. In contrast, pretreatment of εV1-2, a specific PKCε inhibitor, gives opposite results. Collectively, our findings indicate that miR-34a regulates BTB function by targeting PKCε; after phosphorylation, PKCε is activated and contributes to regulation of the expression of tight junction–related proteins, ultimately altering BTB permeability.

Effects of insulin combined with idebenone on blood-brain barrier permeability in diabetic rats

This study investigates the effect of insulin combined with idebenone on blood-brain barrier (BBB) permeability in experimental streptozotocin-induced diabetic rats as well as the underlying mechanisms. With a diabetic rat model, we show that insulin and idebenone normalize body weight and water intake and restore BBB permeability and that their combination displays a synergistic effect. The results from transmission electron microscopy show that the combination of insulin and idebenone significantly closed the tight junction (TJ) in diabetic rats. The results from Western blotting in diabetic rats show that the upregulation of TJ-associated proteins occludin, and zonula occludens (ZO)-1 caused by the combination of insulin and idebenone is more remarkable than that with either agent alone. In addition, the activations of reactive oxygen species (ROS) and advanced glycation end products (AGEs) and the expression levels of receptors for advanced glycation end-products (RAGE) and nuclear factor-κB (NF-κB) were significantly decreased after treatment with insulin and idebenone in diabetic rats. These results suggest that the combination of insulin and idebenone could decrease the BBB permeability in diabetic rats by upregulating the expression of occludin, claudin-5, and ZO-1 and that the ROS/AGE/RAGE/NF-κB signal pathway might be involved in the process.

MiR-18a increased the permeability of BTB via RUNX1 mediated down-regulation of ZO-1, occludin and claudin-5

The purposes of this study were to investigate the possible molecular mechanisms of miR-18a regulating the permeability of blood-tumor barrier (BTB) via down-regulated expression and distribution of runt-related transcription factor 1 (RUNX1). An in vitro BTB model was established with hCMEC/D3 cells and U87MG cells to obtain glioma vascular endothelial cells (GECs). The endogenous expressions of miR-18a and RUNX1 were converse in GECs. The overexpression of miR-18a significantly impaired the integrity and increased the permeability of BTB, which respectively were detected by TEER and HRP flux assays, accompanied by down-regulated mRNA and protein expressions and distributions of ZO-1, occludin and claudin-5 in GECs. Dual-luciferase reporter assay was carried out and revealed RUNX1 is a target gene of miR-18a. Meanwhile, mRNA and protein expressions and distribution of RUNX1 were downregulated by miR-18a. Most important, miR-18a and RUNX1 could reversely regulate the permeability of BTB as well as the expressions and distributions of ZO-1, occludin and claudin-5. Finally, chromatin immunoprecipitation verified that RUNX1 interacted with "TGGGGT" DNA sequence in promoter region of ZO-1, occludin and claudin-5 respectively. Taken together, our present study indicated that miR-18a increased the permeability of BTB via RUNX1 mediated down-regulation of tight junction related proteins ZO-1, occludin and claudin-5, which would attract more attention to miR-18a and RUNX1 as potential targets of drug delivery across BTB and provide novel strategies for glioma treatment.

miR-101 acts as a tumor suppressor by targeting Kruppel-like factor 6 in glioblastoma stem cells

BACKGROUND AND AIMS

Great interest persists in useful therapeutic targets in glioblastoma (GBM). Deregulation of microRNAs (miRNAs) expression has been associated with cancer formation through alterations in gene targets. In this study, we reported the role of miR-101 in human glioblastoma stem cells (GSCs) and the potential mechanisms.

METHODS AND RESULTS

Quantitative real-time PCR showed that miR-101 expression was decreased in GSCs. Overexpression of miR-101 reduced the proliferation, migration, invasion, and promoted apoptosis of GSCs. One direct target of miR-101, the transcription factor Kruppel-like factor 6 (KLF6), was identified using the Dual-Luciferase Reporter Assay System, which mediated the tumor suppressor activity of miR-101. This process was coincided with the reduced expression of Chitinase-3-like protein 1 (CHI3L1) whose promoter could be bound with and be promoted by KLF6 demonstrated by luciferase assays and chromatin immunoprecipitation assays. The downregulation of CHI3L1 led to the inactivation of MEK1/2 and PI3K signal pathways. Furthermore, nude mice carrying the tumors of overexpressed miR-101 combined with knockdown of KLF6 produced the smallest tumors and showed the highest survival rate.

CONCLUSIONS

Our findings provided a comprehensive analysis of miR-101 and further defining it as a potential therapeutic candidate for GBM.

Changes in the numbers of ribbon synapses and expression of RIBEYE in salicylate-induced tinnitus

BACKGROUND

This study was performed to explore the mechanism underlying tinnitus by investigating the changes in the synaptic ribbons and RIBEYE expression in cochlear inner hair cells in salicylate-induced tinnitus.

METHODS

C57BL/6J mice were injected with salicylate (350 mg/kg) for 10 days and grouped. Behavioral procedures were performed to assess whether the animals experienced tinnitus. The specific presynaptic RIBEYE protein and non-specific postsynaptic glutamate receptor 2&3 protein in basilar membrane samples were examined by immunofluorescent labeling. RT-PCR and Western blot assays were used to examine RIBEYE expression. Serial sections were used to build three-dimensional models using 3ds MAX software to evaluate the changes in the synaptic ribbons.

RESULTS

The administration of salicylate increased false positives in the behavioral procedure from 3 d to 10 d. The membrane profiles of inner hair cells in all mice were intact. The number of synaptic ribbons in the salicylate group increased on the 7(th) d and decreased on the 9(th) and 10(th) d. mRNA and protein expression of RIBEYE were initially up-regulated and later down-regulated by injecting salicylate for 10 consecutive days.

CONCLUSION

This change in the ribbon synapses of cochlear inner hair cells in salicylate-induced mice might serve as a compensatory mechanism in the early stages of ototoxicity and contribute to tinnitus later. The alteration of RIBEYE expression could be responsible for the changes in the morphology of ribbon synapses and for salicylate-induced tinnitus.

Topoisomerase I inhibitors, shikonin and topotecan, inhibit growth and induce apoptosis of glioma cells and glioma stem cells

Gliomas, the most malignant form of brain tumors, contain a small subpopulation of glioma stem cells (GSCs) that are implicated in therapeutic resistance and tumor recurrence. Topoisomerase I inhibitors, shikonin and topotecan, play a crucial role in anti-cancer therapies. After isolated and identified the GSCs from glioma cells successfully, U251, U87, GSCs-U251 and GSCs-U87 cells were administrated with various concentrations of shikonin or topotecan at different time points to seek for the optimal administration concentration and time point. The cell viability, cell cycle and apoptosis were detected using cell counting kit-8 and flow cytometer to observe the inhibitory effects on glioma cells and GSCs. We demonstrated that shikonin and topotecan obviously inhibited proliferation of not only human glioma cells but also GSCs in a dose- and time-dependent manner. According to the IC50 values at 24 h, 2 μmol/L of shikonin and 3 μmol/L of topotecan were selected as the optimal administration concentration. In addition, shikonin and topotecan induced cell cycle arrest in G0/G1 and S phases and promoted apoptosis. The down-regulation of Bcl-2 expression with the activation of caspase 9/3-dependent pathway was involved in the apoptosis process. Therefore, the above results showed that topoisomerase I inhibitors, shikonin and topotecan, inhibited growth and induced apoptosis of GSCs as well as glioma cells, which suggested that they might be the potential anticancer agents targeting gliomas to provide a novel therapeutic strategy.

Platelet-derived growth factor BB mediates the glioma-induced migration of bone marrow-derived mesenchymal stem cells by promoting the expression of vascular cell adhesion molecule-1 through the PI3K, P38 MAPK and NF-κB pathways

Platelet-derived growth factor BB (PDGFBB) has been shown to activate the migration of bone marrow-derived mesenchymal stem cells (BM-MSCs), and to contribute to mediating the tropism of BM-MSCs towards gliomas. However, the exact mechanism of this migratory behavior remains to be elucidated. The present study investigated the role of vascular cell adhesion molecule-1 (VCAM-1) in the PDGFBB-induced migration of BM-MSCs, the effect of PDGFBB on VCAM-1 expression of BM-MSCs and related signaling pathways involved in this process. Rat BM-MSCs were isolated and cultured by their characteristics of adherence to plastics. The concentrations of PDGFBB in the conditioned medium of C6 and U87 cells were measured using the ELISA method. In vitro migration assays using a VCAM-1 blocking antibody were performed to evaluate the role of VCAM-1 in PDGFBB-induced migration of BM-MSCs. The effect of rat recombinant PDGFBB on VCAM-1 expression of BM-MSCs was studied by RT-PCR and western blotting. LY294002, SB203580, PD98059, SP600125 and BAY11-7082 were used to explore the role of PI3K, p38 MAPK, MEK, JNK and NF-κB in the related intracellular signal transduction of PDGFBB stimulation on VCAM-1 expression of BM-MSCs. The data demonstrated that the neutralization of VCAM-1 inhibited the migration of BM-MSCs induced by PDGFBB. Additionally, PDGFBB stimulation increased VCAM-1 expression of BM-MSCs, which could be inhibited by LY294002, SB203580 and BAY11-7082. It is reasonable to conclude that PDGFBB significantly enhanced the expression of VCAM-1 in BM-MSCs, which facilitated the migration of BM-MSCs towards PDGFBB. PI3K, p38 MAPK and NF-κB were involved in the signal transduction of this process.

Artemether combined with shRNA interference of vascular cell adhesion molecule-1 significantly inhibited the malignant biological behavior of human glioma cells

Artemether is the derivative extracted from Chinese traditional herb and originally used for malaria. Artemether also has potential therapeutic effects against tumors. Vascular cell adhesion molecule-1 (VCAM-1) is an important cell surface adhesion molecule associated with malignancy of gliomas. In this work, we investigated the role and mechanism of artemether combined with shRNA interference of VCAM-1 (shRNA-VCAM-1) on the migration, invasion and apoptosis of glioma cells. U87 human glioma cells were treated with artemether at various concentrations and shRNA interfering technology was employed to silence the expression of VCAM-1. Cell viability, migration, invasiveness and apoptosis were assessed with MTT, wound healing, Transwell and Annexin V-FITC/PI staining. The expression of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and phosphorylated Akt (p-Akt) was checked by Western blot assay. Results showed that artemether and shRNA-VCAM-1 not only significantly inhibited the migration, invasiveness and expression of MMP-2/9 and p-Akt, but also promoted the apoptosis of U87 cells. Combined treatment of both displayed the maximum inhibitory effects on the malignant biological behavior of glioma cells. Our work revealed the potential therapeutic effects of artemether and antiVCAM-1 in the treatments of gliomas.

[The influence of rhAng-1 on endothelial junctions of BBB after focal cerebral ischemia/reperfusion in rats]

OBJECTIVE

This study was performed to determine whether recombinant human angiopoietin-1 (rhAng-1) decreases the permeability of the blood-brain barrier (BBB) in focal cerebral ischemia and reperfusion rats, whether RhAng-1 opens the BBB by affecting tight junction associated proteins zonnula occludin-1 (ZO-1), occludin and adherens junction protein vascular endothelial (VE)-cadherin.

METHODS

The rats were divided into eight groups randomly( n = 10): (1) sham-operated group; (2) ischemia group; (3)-(5) ischemia/reperfusion (middle cerebral artery occlusion and reperfusion (MCAO/R) 12 h, 48 h, and 7 days) and 0.9% saline groups; (6)-(8) ischemia/reperfusion (MCAO/R 12 h, 48 h, and 7 days) and rhAng-1 groups. The Bee permeability was assessed by Evans blue extravasation. The messenger RNA and protein expressions of ZO-1, occludin, and VE-cadherin were determined by reverse transcription-polymerase chain reaction, Western blot, and immunohistochemistry assays.

RESULTS

The BBB permeability and the brain infarct volume were significantly decreased after rhAng-1 injection. The expressions of ZO-1, occludin, and VE-cadherin were increased after rhAng-1 injection.

CONCLUSION

rhAng-1 may decrease the permeability of BBB in MCAO/R rats by upregulation of ZO-1, occludin, and VE-cadherin.

Curcumin blocks small cell lung cancer cells migration, invasion, angiogenesis, cell cycle and neoplasia through Janus kinase-STAT3 signalling pathway

Curcumin, the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development. However, little is known about its anti-tumor mechanism in small cell lung cancer (SCLC). In this study, we found that curcumin can inhibit SCLC cell proliferation, cell cycle, migration, invasion and angiogenesis through suppression of the STAT3. SCLC cells were treated with curcumin (15 µmol/L) and the results showed that curcumin was effective in inhibiting STAT3 phosphorylation to downregulate of an array of STAT3 downstream targets ,which contributed to suppression of cell proliferation, loss of colony formation, depression of cell migration and invasion. Curcumin also suppressed the expression of proliferative proteins (Survivin, Bcl-X(L) and Cyclin B1), and invasive proteins (VEGF, MMP-2, MMP-7 and ICAM-1). Knockdown of STAT3 expression by siRNA was able to induce anti-invasive effects in vitro. In contrast, activation of STAT3 upstream of interleukin 6 (IL-6) leads to the increased cell proliferation ,cell survival, angiogenesis, invasion, migration and tumor growth. Our findings illustrate the biologic significance of IL-6/JAK/STAT3 signaling in SCLC progression and provide novel evidence that the pathway may be a new potential target for therapy of SCLC. It was concluded that curcumin is a potent agent in the inhibition of STAT3 with favorable pharmacological activity,and curcumin may have translational potential as an effective cancer therapeutic or preventive agent for SCLC.

Glioma cells promote the expression of vascular cell adhesion molecule-1 on bone marrow-derived mesenchymal stem cells: a possible mechanism for their tropism toward gliomas

The tropism of bone marrow-derived mesenchymal stem cells (BMSCs) toward gliomas has been shown by in vitro and in vivo assays. This study was carried out to evaluate the role of vascular cell adhesion molecule-1 (VCAM-1) in the migration of BMSCs towards glioma and the effect of glioma cells on the VCAM-1 expression of BMSCs. BMSCs were isolated according to their adherence to plastic. The tropism of BMSCs toward C6 and U87 glioma and the role of VCAM-1 in this migration were analyzed by in vitro migration assay, separately. Reverse transcription-polymerase chain reaction, immunofluorescence, and Western blot were employed to assess VCAM-1 expression of BMSCs when they were incubated by the conditioned mediums (CM) of C6 or U87 glioma cells. Data revealed that C6 and U87 glioma cells promote the migration of BMSCs, which could be blocked by a VCAM-1-neutralizing antibody. Moreover, VCAM-1 expression of BMSCs was elevated by the incubation of their CM. The results also demonstrated that LY294002, an inhibitor of phosphoinositide-3-kinase (PI3K), significantly inhibited the glioma-induced upregulation of VCAM-1 on BMSCs. These findings suggested that glioma-induced change in VCAM-1 expression of BMSCs may play an important role in their tropism towards glioma, and PI3K is associated with the signal transduction of this process.

Role of RhoA/ROCK signaling in endothelial-monocyte-activating polypeptide II opening of the blood-tumor barrier: role of RhoA/ROCK signaling in EMAP II opening of the BTB

The purpose of the present study was to determine the potential for RhoA/ROCK signaling to play a role in endothelial-monocyte-activating polypeptide (EMAP) II-induced increase in blood-tumor barrier (BTB) permeability in rat brain microvascular endothelial cells (RBMECs). In the present study, we used an in vitro BTB model, a RhoA inhibitor (C3 exoenzyme) and a ROCK inhibitor (Y27632) to determine whether RhoA/ROCK pathway play a role in the process of TJ disassembly, stress fiber formation, MLC and cofilin phosphorylation, as well as increase of BTB permeability induced by EMAP II. The results revealed that BTB permeability was increased by EMAP II induction, and C3 exoenzyme or Y27632 could partially inhibit the EMAP II-induced increase of BTB permeability. The significant down-regulations in tight junction (TJ)-associated proteins occludin, claudin-5 and ZO-1 and stress fiber formation by EMAP II administration were observed, which were partly prevented by C3 exoenzyme or Y27632 pretreatment. Moreover, the significant increases in RhoA activity, myosin light chain (MLC) and cofilin phosphorylation by EMAP II administration were observed, MLC and cofilin phosphorylation were partly inhibited by C3 exoenzyme or Y27632 pretreatment. The present study demonstrates that the activation of RhoA/ROCK signaling in RBMECs was required for the increase of BTB permeability and these effects are related with the ability for RhoA/ROCK to mediate TJ disassembly and stress fiber formation by phosphorylating cofilin and MLC.

The influence of intraoperative pleural perfusion with matrine-cisplatin or cisplatin on stromal cell-derived factor-1 in non-small cell lung cancer patients with subclinical pleural metastasis

The early diagnosis and treatment of non-small cell lung cancer (NSCLC) in patients with subclinical pleural metastasis is currently a challenge. In an effort to establish a method for the diagnosis and treatment of these patients, we conducted a single-blind study during which intraoperative pleural lavage cytology (PLC) was performed in 164 patients with NSCLC without obvious pleural effusion. Stromal cell-derived factor-1 (SDF-1) serum concentrations were analyzed using enzyme-linked immunoassay on day 1 prior to tumor resection and on day 7 postoperatively. Western blot analysis was used for the detection of CXCR4 protein expression in resected tumors. Intraoperative pleural perfusion chemotherapy, with either cisplatin or cisplatin plus matrine, was given to patients with positive PLC. A group of 30 patients with NSCLC that did not undergo intraoperative PLC were used as a control group. Of the 164 study patients, 41 (25%) patients had positive PLC. Serum SDF-1 concentrations were higher in PLC-positive patients compared with patients negative for PLC and control patients. Serum SDF-1 concentrations were also lower at postoperative day 7 in patients treated with cisplatin plus matrine compared with control patients and those perfused with cisplatin alone. A lower incidence of chemotherapy-related adverse events was observed in patients treated with cisplatin plus matrine versus those treated with cisplatin alone during the first postoperative month. Patients with positive PLC showed a higher CXCR4 protein expression than patients with negative PLC. Based on the results of this study, PLC combined with serum SDF-1 concentration measurements may be considered as an effective index to determine the risk of subclinical pleural metastasis in patients with lung cancer. In addition, cisplatin plus matrine was confirmed as an initial approach for pleural perfusion and was superior to cisplatin alone.

The modulation of protein kinase A and heat shock protein 70 is involved in the reversible increase of blood-brain tumor barrier permeability induced by papaverine

Intra-arterial administration of papaverine has been revealed to cause an increase in the blood-brain tumor barrier (BTB) permeability. The exact mechanism of papaverine opening the BTB in chemotherapy of malignant cerebral tumors, however, has not been well described. We used a rat brain glioma (C6) model for studying how papaverine modulates the permeability of BTB by monitoring the activities of the tight junction (TJ)-associated protein occludin, claudin-5 and cytoskeletal protein filamentous actin (F-actin) and whether protein kinase A (PKA) and heat shock protein 70 (HSP70) were involved in the regulation of this biological process. The levels of occludin, claudin-5 and F-actin protein in the tumor tissues were down-regulated by papaverine via immunohistochemistry, immunofluorescence assays and Western blot, corresponding to the time-dependent change of the BTB permeability. The most obvious attenuation of occludin, claudin-5 and F-actin protein was observed at 1h after papaverine perfusion, companied by a significant decrease in expression levels of PKA protein. The expression level of HSP70 in the tumor tissues was also progressively increased after papaverine perfusion and reached the maximum at 3h. The results demonstrate that the reversible openning of BTB mediated by papaverine may be associated with the functional combination between PKA and HSP70. That is, BTB opening may be attributable to the down-regulation of occludin, claudin-5 and F-actin, and cAMP/PKA signaling pathway might be involved in this process. HSP70 is likely responsible for the BTB closing, which helping the repairment of injured TJ protein and the rebuilding of the BTB.

Effects of synaptic plasticity regulated by 17beta-estradiol on learning and memory in rats with Alzheimer's disease

OBJECTIVE

To investigate whether estrogen modulates learning and memory and long-term potentiation (LTP) in the hippocampus of rats with Alzheimer's disease (AD).

METHODS

The rats were divided into ovariectomy (OVX) and estrogen replacement therapy (ERT) groups. Rats in the ERT group received OVX, followed by ERT, while rats in the OVX group received only OVX. The rat model of AD was established by injection of 1 microL (10 microg/microL) amyloid-beta peptide 1-40(Abeta1-40) into the hippocampus. The learning and memory ability and LTP were determined by Morris water maze and electrophysiological method, respectively.

RESULTS

The escape latency in Morris water maze significantly decreased in ERT group compared with that in OVX group (P< 0.05). Besides, rats in ERT group exhibited a significant enhancement of the magnitude of LTP at 30 min after high-frequency stimulation (HFS), compared with that in OVX group (P< 0.01).

CONCLUSION

ERT can attenuate the cognitive deficits in the rat model of AD, and estrogen can regulate LTP and synaptic remodeling in AD rats.

Endothelial-monocyte-activating polypeptide II increases blood-tumor barrier permeability by down-regulating the expression levels of tight junction associated proteins

This study was performed to determine whether endothelial-monocyte-activating polypeptide (EMAP) II increases the permeability of the blood-tumor barrier (BTB) in the rat model of C6 glioma, and whether EMAP II opens the BTB by affecting tight junction (TJ) associated proteins zonula occluden-1 (ZO-1), occludin and claudin-5. The rats were divided into eight groups randomly: control group, EMAPII 0h group, EMAPII 0.5h group, EMAPII 1h group, EMAPII 2h group, EMAPII 3h group, EMAPII 6h group and EMAPII 12h group. The BTB permeability was assessed by Evans blue extravasation. The mRNA and protein expressions of ZO-1, occludin, and claudin-5 were determined by reverse transcriptase-polymerase chain reaction, western blot, and immunohistochemistry assays. The BTB permeability significantly increased after EMAP II injection in different doses (40ng/kg, 80ng/kg and 160ng/kg). The BTB permeability started to increase from 0.5h, reached a peak at 1h, and finally returned to the level of EMAP II 0h group after EMAP II injection at dose of 80ng/kg. The mRNA and protein expression levels of ZO-1, occludin and claudin-5 were significantly decreased after EMAP II injection. This study demonstrates for the first time that EMAP II increases the permeability of BTB selectively, and the possible mechanism is associated with the down-regulation of ZO-1, occludin and claudin-5.

Bradykinin increases blood-tumor barrier permeability by down-regulating the expression levels of ZO-1, occludin, and claudin-5 and rearranging actin cytoskeleton

Bradykinin (BK) has been shown to open blood-tumor barrier (BTB) selectively and to increase permeability of the BTB transiently, but the mechanism is unclear. This study was performed to determine whether BK opens the BTB by affecting the tight junction (TJ)-associated proteins zonula occluden-1 (ZO-1), occludin, and caludin-5 and cytoskeleton protein filamentous actin (F-actin). In rat brain glioma model and BTB model in vitro, we find that the protein expression levels of ZO-1, occludin, and claudin-5 are attenuated by BK induction. Immunohistochemistry and immunofluorescence assays show that the attenuated expression of ZO-1, occludin, and claudin-5 and F-actin is most obvious in the smaller tumor capillaries (<20 microm) after BK infusion, and there is no change in the larger tumor capillaries (>20 microm). The redistribution of ZO-1, occludin, and claudin-5 and rearrangement of F-actin in brain microvascular endothelial cells are observed at the same time. Meanwhile, Evans blue assay shows that the permeability of BTB increases after BK infusion. Transmission electron microscopy indicates that TJ is opened and that pinocytotic vesicular density is increased. Transendothelial electrical resistance (TEER) and horseradish peroxidase flux assays also reveal that TJ is opened by BK induction. In addition, radioimmunity and Western blot assay reveal a significant decrease in expression levels of cAMP and catalytic subunit of protien kinase A (PKAcs) of tumor tissue. This study demonstrates that the increase of BK-mediated BTB permeability is associated with the down-regulation of ZO-1, occludin, and claudin-5 and the rearrangement of F-actin and that cAMP/PKA signal transduction system might be involved in the modulating process.

[Effects of aluminum on the integrity of blood brain barrier in juvenile rats]

OBJECTIVE

To investigate the effects of aluminum on the integrity of blood brain barrier in juvenile rats.

METHODS

The 40-day old Sprague-Dawley (SD) rats were exposed to aluminium chloride by intraperitoneal injection, at a dose of Al3+ 0 mg/kg, 2.5 mg/kg, 5 mg/kg, 10 mg/kg, respectively. Morris water amaze system was used to test the learning and memory ability. The Evans blue content in brain was analyzed after injection. The ultrastructure's change of the blood brain barrier (BBB) was observed with transmission electron microscope. The expression of occluding protein in BBB was determined by Western blot method.

RESULTS

As compared with control group, the permeability of BBB in mid-level Al and high-level Al was enhanced (P <0.01), the expression of occluding protein was descended (P <0.01). The ultrastructures of the BBB were changed. No differences between every group on learning and memory ability (P>0.05).

CONCLUSIONS

Short time and low dose of Al might not change the ability of learning and memory in juvenile rats, however the permeability and ultrastructures of the BBB might be significantly changed.

Dexamethasone enhances adenosine 5'-triphosphate-sensitive potassium channel expression in the blood-brain tumor barrier in a rat brain tumor model

This study was performed to determine whether dexamethasone (DEX) had an effect on ATP-sensitive potassium channels (K(ATP) channels) in blood-brain tumor barrier (BTB). Using a rat brain glioma model, we found that DEX could significantly increase the expression of K(ATP) channels protein at tumor sites. And bradykinin-induced increase of K(ATP) channels protein was further enhanced after DEX pretreatment for 3 consecutive days via Western blots and immunohistochemistry methods. In addition, DEX pretreatment enhanced bradykinin-mediated increase of the density of I(KATP) in the cultured rat C6 glioma cells using the patch-clamp technique in a whole-cell configuration. DEX significantly decreased the BTB permeability, but it did not reduce bradykinin-mediated BTB permeability increase, which were significantly attenuated by the K(ATP) channel antagonist glibenclamide. This led to the conclusion that DEX-mediated change in BTB permeability is, at least partly, due to accelerated formation of K(ATP) channel, an important target in the biochemical regulation of this process.

Effects of KB-R9032, a new Na+/H+ exchange inhibitor, on canine coronary occlusion/reperfusion-induced ventricular arrhythmias

We investigated the effects of KB-R9032 (N-(4-isopropyl-2,2-dimethyl-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbonyl) guanidine methanesulfonate), a new Na(+)/H(+) exchange inhibitor, on a coronary artery occlusion/reperfusion-induced arrhythmia model in pentobarbital anesthetized dogs. KB-R9032 reduced the number of ventricular premature contractions seen during the coronary occlusion, while it did not alter the heart rate, mean blood pressure, or electrocardiographic parameters (PR, QRS, or QTc interval). KB-R9032 also decreased the incidence of fatal ventricular fibrillation during coronary artery occlusion and/or after reperfusion. These antiarrhythmic effects were observed not only in the pre-ischemic administration group, but also in the group given KB-R9032 at the 15th min of the 30-min occlusion. These findings support the view that Na(+)/H(+) exchanger may play an important role in inducing coronary ischemia/reperfusion arrhythmias. This suggests that the use of Na(+)/H(+) exchange inhibitors, such as KB-R9032, may be an effective clinical approach to suppress sudden cardiac death due to acute myocardial ischemia/reperfusion such as during coronary bypass surgery, cardiac valve surgery, or percutaneous transluminal coronary angioplasty.

[Relationship between gastric cancer and gene amplification of p14 and mdm2]

BACKGROUND & OBJECTIVE

Some genes are related to the occurrence of tumor. p53 is one of these kinds of gene. Mdm2 and p14 can modulate the function of p53. However, the reports about the function of mdm2 and p14 in gastric tumor are rare. The aim of this study was to observe the change of oncogene mdm2 and suppressor cancer gene p14 in gastric cancer cell and to investigate the relationship of mdm2, p14 with gastric cancer.

METHODS

A total of 55 gastric mucosal biopsy specimens were enrolled, including 10 of normal gastric mucosa and 45 gastric tumor, which were proved pathologically as adenoma, including 15 poorly, moderately, and well differentiated specimens, respectively. The mRNA expression of mdm2 and p14 in gastric cancer were identified by reverse transcription polymerase chain reaction (RT-PCR), and the relationship of mdm2, p14 with gastric cancer was analyzed.

RESULTS

(1) There was significant difference of the expression positive ratio of mdm2 mRNA between gastric tumor and normal gastric tissues (73.3% vs. 40%) (P< 0.05) [93.3% for the well differentiated specimens, 80.0% for the moderately differentiated specimens, and 46.6% for the poorly differentiated specimens]. There was significant difference between any two groups of the three specimens (P< 0.05). (2) There was no significant difference of the expression positive ratio of p14 mRNA between gastric tumor and normal gastric tissues (60.0% vs. 50.0%) (P >0.05) [60.0% for the well differentiated specimens, 66.6% for the moderately differentiated specimens, and 53.5% for the poorly differentiated specimens]. There was no significant difference between any two groups of the three specimens (P >0.05).

CONCLUSION

The mRNA expression of mdm2 is closely correlated with the progression of gastric cancer. The relationship between p14 and gastric tumor has not been tested in this study and further study will be needed.

Effects of qian-kun-nin, a Chinese herbal medicine formulation, on HIV positive subjects: a pilot study

Qian-kun-nin is a Chinese herbal formulation considered to have anti-infection, anti-tumor and immuno-enhancing properties. Data from previous investigations showed that qian-kun-nin causes HIV growth inhibition and immunomodulation in vitro, suggesting that this formula has the ability to inhibit HIV and modulate impaired immune functions in humans. We conducted this pilot study to evaluate the anti-retroviral and immunological enhancing effects of this formula on HIV positive subjects. Eight subjects completed the study, receiving oral qian-kun-nin capsules for 24 consecutive weeks in a single blind design. Compared to baseline level, the plasma virus load decreased significantly at the end of week 12 (p < 0.01) and week 24 (p < 0.01), respectively. Four weeks after cessation of qian-kun-nin treatment, plasma virus load was still significantly lower compared to baseline (p < 0.01). Blood CD4 cell counts were increased significantly at the end of the 12th week compared to the baseline level (p < 0.01). No adverse effects were observed, and no significant side effects were recorded in any subjects. These data suggest that qian-kun-nin has therapeutic potential in the treatment of HIV positive patients.

Effects of an antiarrhythmic drug A-2545 on canine ventricular arrhythmia models; comparison with mexiletine and flecainide

We investigated effects of a new Na+ channel blocking antiarrhythmic drug, A-2545, N-3 (2,2,5,5-tetramethyl-3-pyrroline-3-carboxamido)-propyl-phthalimide-hydro chloride, on various canine ventricular automaticity arrhythmias induced by two-stage coronary ligation, digitalis and adrenaline, and compared them with those of mexiletine. A-2545 showed antiarrhythmic effects, significantly decreasing the arrhythmic ratio of 24-h and 48-h coronary ligation-, digitalis- and adrenaline-induced automaticity arrhythmias. The antiarrhythmic plasma concentrations (IC50) of A-2545, 2 mg kg(-1) 10 min(-1), i.v., for 24-h and 48-h coronary ligation-, digitalis- and adrenaline-induced arrhythmias were 1.8, 1.3, 5.8 and 3.7 microg ml(-1), respectively, and that calculated for oral A-2545 (25 mg kg(-1)) in 24-h coronary ligation-induced arrhythmia was 1.8 microg ml(-1). A-2545 is specifically potent in suppressing coronary ligation-induced arrhythmias, i.e., decreasing the arrhythmic ratio nearly to zero by oral administration, and among the intravenously given experiments A-2545 was effective at lower concentrations than other arrhythmia models; A-2545, 2 mg kg(-1) 10 min(-1), was equipotent to 5 mg kg(-1) 10 min(-1) mexiletine in suppressing 24-h coronary ligation-induced arrhythmia, indicating that A-2545 is more potent than mexiletine. In order to determine whether A-2545 has arrhythmogenic effects, we used programmed electrical stimulation (PES)-induced reentry arrhythmias in dogs with old myocardial infarction and compared effects of A-2545 and flecainide. A-2545, 2 and 5 mg kg(-1) 10 min(-1), significantly suppressed the PES-induced arrhythmias in all six dogs without aggravating them. These arrhythmias were not markedly suppressed by flecainide either with 1 or 3 mg kg(-1) 1O min(-1); moreover even in one out of six dogs aggravation of arrhythmia was noted after 1 mg kg(-1) 10 min(-1). In conclusion, A-2545 suppressed various canine ventricular arrhythmias, and the antiarrhythmic effect of A-2545 was more potent than that of mexiletine, and A-2545 did not show arrhythmogenic effects compared to flecainide.

Antiarrhythmic effects of cariporide, a novel Na+-H+ exchange inhibitor, on reperfusion ventricular arrhythmias in rat hearts

Cariporide (4-isopropyl-3-methylsulphonylbenzoyl-guanidine methanesulphonate: HOE642) is a novel Na+-H+ exchange subtype 1 inhibitor and has antiarrhythmic effects on ischemia/reperfusion arrhythmias without apparent cardiovascular effects in dogs and rats when given before coronary occlusion. The aim of this study was to determine the minimum effective dose and to examine the dose related effects of cariporide when it was administered before and during coronary occlusion as well as simultaneously with reperfusion. In the pre-treatment group, cariporide dose-dependently reduced the ventricular tachycardia duration from 140 to 36 (P < 0.01), 59 (P < 0.05) and 23 s (P < 0.01) with 0.03, 0.1 and 1 mg/kg, respectively, and reduced the incidence of reperfusion-induced ventricular tachycardia from 100 to 50 and 58% (P < 0.01), ventricular fibrillation from 83 to 8 and 0% (P < 0.01), and mortality from 75 to 8 and 8% (P < 0.01) with 0.1 and 1 mg/kg, respectively. In the post-treatment group, cariporide dose-dependently reduced the ventricular tachycardia duration from 92 to 37, 40, 42 (P < 0.05) and 24 s (P < 0.01) with 0.03, 0.1, 0.3 and 1 mg/kg, respectively, and the incidence of ventricular tachycardia from 100 to 53% (P < 0.01) by 1 mg/kg, and ventricular fibrillation from 87 to 33, 7 and 7% (P < 0.01), and the mortality from 73 to 27 (P < 0.05), 0 and 7% (P < 0.01) with 0.1, 0.3 and 1 mg/kg, respectively. In the group with simultaneous injection, both doses of cariporide (1 and 3 mg/kg) reduced the incidence of ventricular fibrillation from 83 to 42% (P < 0.05). The heart rate, blood pressure and QT interval did not change after drug treatment.

Antiarrhythmic effects of an aconitine-like compound, TJN-505, on canine arrhythmia models

We examined the effects of an aconitine-like compound, TJN-505 (1alpha-16beta-dimethoxy-20-ethyl-14alpha-(4-methox ybenzoyloxy)-aconitan-8,13-diol hydrochloride), on canine arrhythmias provoked by digitalis, two-stage coronary ligation, adrenaline, programmed electrical stimulation, or aconitine. TJN-505 (2-2.5 mg/kg i.v.) suppressed digitalis-, two-stage coronary ligation- and adrenaline-induced ventricular arrhythmias. The antiarrhythmic plasma concentrations (IC50) of TJN-505 for these arrhythmia models were 1.26, 0.94 and 1.31 microg/ml, respectively. TJN-505 (2 mg/kg i.v. followed by the infusion of 0.1 mg/kg per min) prolonged PR, QRS, QTc and JTc intervals and the ventricular effective refractory period and reduced the incidence of programmed electrical stimulation-induced arrhythmias in dogs with 7-day-old myocardial infarction (P < 0.05). TJN-505 (2 mg/kg i.v.) also suppressed the aconitine-induced atrial arrhythmias. In conclusion, TJN-505 suppressed various canine ventricular and atrial arrhythmias and seems to act as a blocker of multiple channels.

Antiarrhythmic effects of HOE642, a novel Na(+)-H+ exchange inhibitor, on ventricular arrhythmias in animal hearts

HOE642 (4-isopropyl-3-methylsulphonylbenzoyl-guanidine methanesulphonate), a novel Na(+)-H+ exchange subtype 1 inhibitor, was investigated for its possible antiarrhythmic effects on coronary artery ligation/reperfusion and ouabain-induced arrhythmias in the canine heart which may occur after intracellular Ca2+ overload. Also, the effects of HOE642 on coronary artery ligation/reperfusion of the left coronary artery were tested in rat hearts. HOE642 (1 mg/kg) significantly suppressed the occurrence of fatal ventricular fibrillation during coronary artery ligation and after reperfusion in dogs (2 out of 8 dogs in the treated group compared to 7 out of 8 dogs in the control group, P < 0.05), but did not suppress ventricular premature contractions and ventricular tachycardia during ischemia in the canine hearts. HOE642 at the same dose markedly reduced the total duration and the incidence of reperfusion-induced ventricular tachycardia, and the incidence and mortality of reperfusion-induced ventricular fibrillation in rats (ventricular tachycardia duration, 159 +/- 12 s to 21 +/- 8 s, P < 0.01; ventricular tachycardia, 100% to 69%; ventricular fibrillation, 89% to 0%, P < 0.01; mortality, 89% to 11%, P < 0.01). The heart rate, blood pressure, QT interval and ST segment did not change in the canine and rat hearts. HOE642 slightly decreased the arrhythmic ratio of the ouabain-induced arrhythmia only at two time points (28 and 35 min after injection) in the canine hearts. In conclusion, HOE642 has obvious antifibrillatory effects on ischemia/reperfusion arrhythmias and, in addition, has a weak suppressing effect on the ouabain-induced arrhythmia.

Effects of the antihypoxic and neuroprotective drug, lubeluzole, on repolarization phase of canine heart assessed by monophasic action potential recording

The cardiovascular effects of the antihypoxic and neuroprotective drug, lubeluzole, were investigated using beagle dogs anesthetized with halothane. Endocardial-contact electrode catheter was used for continuous monitoring of monophasic action potential (MAP), which could provide a precise information of repolarization phase. Intravenous administration of an efficacious dose of lubeluzole (0.63 mg/kg, n = 6) slightly decreased both the heart rate and the blood pressure. It did not change PQ interval and QRS width, while it significantly prolonged QT interval, corrected QT (QTc) and the duration of the MAP during the observation period over 60 min. The effects of drug on repolarization phase were late-onset and long-lasting compared with the time course of plasma drug concentrations, which changed as predicted by the two-compartment theory of pharmacokinetics. Additional injection of lubeluzole (2.5 mg/kg, n = 6) showed qualitatively similar changes to those of lower dose, and did not induce the cardiovascular collapse in any dog. Neither afterdepolarization nor ventricular escaped beat was detected during the observation period. The drug concentration in cardiac tissue was correlated linearly with the plasma drug concentration at 60 min after the second drug administration. These results indicate that lubeluzole exerts only minor cardiovascular effects except the prolongation of the repolarization period. The monitoring of plasma drug concentration may be helpful to estimate the steady-state distribution of drug to the heart, but less helpful to predict the QT prolongation. In future clinical trials, care must be taken with patients, especially those at risk to have prolonged repolarization.

Effects of zatebradine on ouabain-, two-stage coronary ligation- and epinephrine-induced ventricular tachyarrhythmias

To determine whether a hyperpolarization-activated current (If) participates in ventricular tachyarrhythmias, we investigated the effects of zatebradine, an I(f) inhibitor, on the ventricular tachyarrhythmias induced by ouabain, two-stage coronary ligation and epinephrine infusion in the dog heart. We determined atrial rate, ectopic ventricular rate, total heart rate and arrhythmic ratio (the number of ectopic ventricular beats divided by total heart beats). Zatebradine (0.15, 0.5 and 1.5 mg/kg, i.v.) dose dependently decreased the arrhythmic ratio, ectopic ventricular rate and atrial rate of the ouabain-induced ventricular tachyarrhythmias in pentobarbital-anesthetized dogs. The inhibition by zatebradine of the ventricular arrhythmias needed larger doses than the inhibition of the atrial rate. Zatebradine weakly depressed the ectopic ventricular rate but not the arrhythmic ratio of the ventricular arrhythmias induced by two-stage coronary ligation 24 h after the ligation in conscious dogs. Although neither the ectopic ventricular rate nor the arrhythmic ratio of the epinephrine-induced ventricular arrhythmias was affected by zatebradine, after treatment with zatebradine, the arrhythmias elicited by epinephrine developed more slowly. Together with the previously reported spectra of the effects of the antiarrhythmic agents in three ventricular tachyarrhythmia models, our results suggest that zatebradine may improve automaticity-related ventricular tachyarrhythmias due to I(f) inhibition or to other undetermined mechanisms in the heart.

Effects of MCI-154, a new cardiotonic Ca2+ sensitizer, on ventricular arrhythmias and membrane ionic currents

We examined whether a new positive inotropic agent with Ca(2+)-sensitizing activity, MCI-154, 6-[4-(4-pyridylamino)phenyl]-4, 5-dihydro-3-(2H)-pyridazinone hydrochloride trihydrate, had deleterious effects on ventricular arrhythmias, since several phosphodiesterase III inhibitors have been shown to aggravate arrhythmias in our earlier studies. Continuous infusion of MCI-154 (1 microgram/kg/min for 15 min) did not suppress or aggravate the arrhythmias generated in the two-stage coronary ligation-, digitalis- and adrenaline-induced canine arrhythmia models studied. Also in the case of a bolus injection of 30 micrograms/kg, MCI-154 did not aggravate the adrenaline-induced arrhythmias. To explain these results in vivo, a whole-cell voltage-clamp experiment on guinea-pig ventricular cells was performed. MCI-154 (10-100 microM) did not increase the inward Ca2+ current under the condition where these currents were increased by isoprenaline. These results indicate that MCI-154 does not aggravate ventricular arrhythmias and does not act on membrane currents associated with arrhythmogenesis. Thus, MCI-154 may become a useful positive inotropic agent with little arrhythmogenic effect.

Antiarrhythmic and proarrhythmic effects of sematilide in canine ventricular arrhythmia models

Using canine ventricular arrhythmia models induced by two-stage coronary ligation, digitalis, adrenaline, coronary ligation and reperfusion, and programmed electrical stimulation (PES), we examined the antiarrhythmic or proarrhythmic effects of sematilide, N-[2(diethylamino)ethyl]-4-[(methylsulfonyl)amino]-benzamide hydrochloride. Sematilide in an intravenous (i.v.) dose range of 0.3 to 6.0 mg/kg prolonged the QTc interval, but had an antiarrhythmic effect only on the arrhythmias induced by PES (7 out of 10 dogs with old myocardial infarction). Sematilide was not effective on coronary ligation and reperfusion arrhythmia or the spontaneously occurring automaticity arrhythmias induced by two-stage coronary ligation, digitalis and adrenaline, respectively, and even aggravated digitalis- and adrenaline-induced arrhythmias. These results indicate that the class III agent sematilide is similar to other new class III agents, such as d-sotalol, E-4031 and MS-551, in that it was not effective on the automaticity arrhythmias, but different from these new class III agents, in that sematilide prevented only the induction of ventricular arrhythmias induced by PES and did not suppress the coronary ligation-reperfusion arrhythmias. The PES induced arrhythmias are thought to be induced exclusively by a reentrant mechanism, but the reperfusion arrhythmias may involve not only re-entry, but also automaticity, and we reported the effectiveness of MS-551, E-4031 and d-sotalol on the latter arrhythmia. Sematilide is different in that it even aggravated some automaticity arrhythmias.

Transient increase in human muscle sympathetic nerve activity during manual acupuncture

To clarify the effects of manual acupuncture on the autonomic nervous system, we measured efferent muscle sympathetic nerve activity (MSNA) from the right peroneal nerve while simultaneously recording blood pressure and heart rate both during the resting period and after manual acupuncture applied to the Tsusanli acupoint of the same limb. The needle was rotated intermittently for 30 s at 5-min intervals. MSNA increased transiently with the suppression of heart rate during rotation of the acupuncture needle. No consistent change in blood pressure was found throughout the acupuncture session. After removal of the needle, both the MSNA and heart rate returned to the initial control values, and the mean blood pressure showed an increase over the resting value. MSNA showed a negative correlation with heart rate in four out of five subjects who received acupuncture. These results suggest that the coactivation of cardiac vagal and muscle sympathetic nerves is evoked by the acupuncture maneuver.