Yurong Li

The role of protein kinase C in the opening of blood-brain barrier induced by electromagnetic pulse.

The aim of this study was to determine the role of protein kinase C signaling in electromagnetic pulse (EMP)-induced blood-brain barrier (BBB) permeability change in rats. The protein level of total PKC and two PKC isoforms (PKC-alpha, and PKC-beta II) were determined in brain cerebral cortex microvessels by Western blot after exposing rats to EMP at 200kV/m for 200 pulses with 1Hz repetition rate. It was found that the protein level of PKC and PKC-betaII (but not PKC-alpha) in cerebral cortex microvessels increased significantly at 0.5h and 1h after EMP exposure compared with sham-exposed animals and then recovered at 3h. A specific PKC antagonist (H7) almost blocked EMP-induced BBB permeability change. EMP-induced BBB tight junction protein ZO-1 translocation was also inhibited. Our data indicated that PKC signaling was involved in EMP-induced BBB permeability change and ZO-1 translocation in rat.

EMP-induced alterations of tight junction protein expression and disruption of the blood-brain barrier.

The blood-brain barrier (BBB) is critical to maintain cerebral homeostasis. In this study, we examined the effects of exposure to electromagnetic pulse (EMP) on the functional integrity of BBB and, on the localization and expression of tight junction (TJ) proteins (occludin and ZO-1) in rats. Animals were sham or whole-body exposed to EMP at 200 kV/m for 400 pulses. The permeability of BBB in rat cerebral cortex was examined by using Evans Blue (EB) and lanthanum nitrate as vascular tracers. The localization and expression of TJ proteins were assessed by western blot and immunofluorescence analysis, respectively. The data indicated that EMP exposure caused: (i) increased permeability of BBB, and (ii) altered localization as well as decreased levels of TJ protein ZO-1. These results suggested that the alteration of ZO-1 may play an important role in the disruption of tight junctions, which may lead to dysfunction of BBB after EMP exposure.

A specific miRNA signature promotes radioresistance of human cervical cancer cells

BackgroundThe mechanisms responsible for cervical cancer radioresistance are still largely unexplored. The present study aimed to identify miRNAs associated with radioresistance of cervical cancer cells.MethodsThe radioresistant cervical cancer cell variants were established by repeated selection with irradiation. The miRNA profiles of radioresistant cells and their corresponding controls were analyzed and compared using microarray. Differentially expressed miRNAs were confirmed by quantitative real-time PCR. Cervical cancer cells were transfected with miRNA-specific mimics or inhibitors. Radiosensitivity of cervical cancer cells were determined using colony-forming assay.ResultsAmong the differentially expressed miRNAs, 20 miRNAs showed the similar pattern of alteration (14 miRNAs were overexpressed whilst 6 were suppressed) in all three radioresistant cervical cancer cell variants compared to their controls. A miRNA signature consisting of 4 miRNAs (miR-630, miR-1246, miR-1290 and miR-3138) exhibited more than 5 folds of increase in radioresistant cells. Subsequent analysis revealed that these four miRNAs could be up-regulated in cervical cancer cells by radiation treatment in both time-dependent and dose-dependent manners. Ectopic expression of each of these 4 miRNAs can dramatically increase the survival fraction of irradiated cervical cancer cells. Moreover, inhibition of miR-630, one miRNA of the specific signature, could reverse radioresistance of cervical cancer cells.ConclusionsThe present study indicated that miRNA is involved in radioresistance of human cervical cancer cells and that a specific miRNA signature consisting of miR-630, miR-1246, miR-1290 and miR-3138 could promote radioresistance of cervical cancer cells.

TCTP overexpression is associated with the development and progression of glioma

Upregulation of translationally controlled tumor protein (TCTP) has been reported in a variety of malignant tumors. However, the impact of TCTP in glioma remains unclear. The objective of this study was to investigate the expression and prognostic value of TCTP in glioma patients. Western blot analysis was used to characterize the expression patterns of TCTP in 45 glioma and 22 normal brain tissues. Immunohistochemistry on a tissue microarray containing 127 cases of glioma was performed to analyze the association between TCTP expression and clinicopathological features. Compared with normal brain tissues, TCTP expression was significantly higher in glioma tissues (p <0.001). In addition, high TCTP expression in glioma was significantly associated with advanced pathological grade (p = 0.018). Kaplan–Meier analysis showed that patients with glioma and higher TCTP expression tend to have shorter overall survival time (p <0.001). In multivariate analysis, TCTP expression was proved to be an independent prognostic factor for patients with glioma (p <0.001). In conclusion, this study confirmed the overexpression of TCTP and its association with tumor progression in glioma. It also provided the first evidence that TCTP expression in glioma was an independent prognostic factor of patients, which might be a potential diagnostic and therapeutic target of glioma.

Comparative Investigations on the Protective Effects of Rhodioside, Ciwujianoside-B and Astragaloside IV on Radiation Injuries of the Hematopoietic System in Mice

The aim of this study was to investigate the protective effects of three glycosides (rhodioside, ciwujianoside‐B and astragaloside IV) on the hematopoietic system in the mice exposed to γ‐rays, and to examine the possible mechanisms involved. Mice were pretreated with the glycosides (40 mg/kg, i.g.) daily for 7 days prior to radiation. The survival of mice pretreated with three glycosides after total body irradiation (6.0 Gy) was examined. Peripheral blood leucocytes and endogenous spleen colony counts, colony‐forming unit‐granulocyte macrophage assay, analysis of DNA content and apoptosis rate determination were performed to evaluate the effects of the three glycosides on hematogenesis. The fragmentation of double‐stranded DNA in lymphocytes was detected by the comet assay. The changes in cell cycle were analysed by flow cytometry. Furthermore, the expression levels of Bcl‐2, Bax and nuclear factor‐kappa B (NF‐κB) were measured by western blot and the electrophoretic mobility shift assay. The results showed that pretreatment with all of the glycosides improved survival time and increased the number of leucocytes, spleen colonies and granulocyte‐macrophage colonies in mice exposed to 6.0 Gy γ‐radiation. Rhodioside showed more protective efficacy than both ciwujianoside‐B and astragaloside IV. All three glycosides significantly increased the proliferation abilities of bone marrow cells, and decreased the ratio of cells in G0/G1 phase. Further analysis showed that these three glycosides were able to decrease DNA damage and the increment in the Bax/Bcl‐2 ratio induced by radiation. In summary, the three glycosides showed radioprotective effects on the hematopoietic system in mice, which was associated with changes in the cell cycle, a reduction in DNA damage, and down‐regulation of the ratio of Bax/Bcl‐2 in bone marrow cells exposed to radiation. Copyright

Overexpression of keratin 17 is associated with poor prognosis in epithelial ovarian cancer

The aim of this study was to investigate the association between keratin 17 (K17) expression and the clinicopathological features of patients with epithelial ovarian cancer (EOC). K17 expression was detected by real-time quantitative RT-PCR in EOC and adjacent noncancerous tissues. In addition, K17 expression was analyzed by immunohistochemistry in 104 clinicopathologically characterized EOC cases. The expression levels of K17 mRNA and protein in EOC tissues were both significantly higher than those in noncancerous tissues. In addition, positive expression of K17 correlated with the clinical stage (p = 0.001). Furthermore, Kaplan–Meier survival analysis showed that a high expression level of K17 resulted in a significantly poor prognosis of EOC patients. Multivariate analysis revealed that EOC expression level was an independent prognostic parameter for the overall survival rate of EOC patients. Our data are the first to suggest that increased K17 expression in EOC is significantly associated with aggressive progression and poor prognosis. K17 may be an important molecular marker for predicting the carcinogenesis, progression, and prognosis of EOC.

Elevated vascular endothelial growth factor levels induce hyperpermeability of endothelial cells in hantavirus infection.

Objective: To investigate the role of vascular endothelial growth factor (VEGF) in haemorrhagic fever with renal syndrome (HFRS). Methods: VEGF, soluble VEGF receptor (sVEGFR)-2, angiopoietin (Ang)-1, tumour necrosis factor (TNF)-α and interferon (IFN)-γ levels were measured in serum samples from 68 patients with HFRS. Cultured human umbilical vein endothelial cells (HUEVCs) were infected by Hantaan virus (HTNV) and/or stimulated with recombinant VEGF; dextran permeability of the cells was determined. Claudin-1 and vascular endothelial (VE)-cadherin levels were determined by real-time reverse transcription-polymerase chain reaction and Western blot analyses. Results: Serum VEGF, TNF-α and IFN-γ levels were significantly elevated, whereas sVEGFR2 and Ang-1 levels were reduced, during the acute phase of HFRS. In vitro cell permeability was unaffected by HTNV infection or VEGF stimulation alone, but the combination of HTNV infection and VEGF treatment significantly increased the permeability of endothelial cell monolayers in a time-dependent manner. Claudin-1 and VE-cadherin were downregulated at both the mRNA and protein level by combined HTNV infection and VEGF stimulation. Conclusions: Elevated VEGF induced by HTNV infection may play an important role in the vascular hyperpermeability that is characteristic of HFRS.

Knock-down of NDRG2 sensitizes cervical cancer Hela cells to cisplatin through suppressing Bcl-2 expression

BackgroundNDRG2, a member of N-Myc downstream regulated gene family, plays some roles in cellular stress, cell differentiation and tumor suppression. We have found that NDRG2 expression in cervical cancer Hela cells increases significantly upon stimulation with cisplatin, the most popular chemotherapeutic agent currently used for the treatment of advanced cervical cancer. This interesting phenomenon drove us to evaluate the role of NDRG2 in chemosensitivity of Hela cells.MethodsIn the present study, RNA interference was employed to down-regulate NDRG2 expression in Hela cells. RT-PCR and Western blot were used to detect expression of NDRG2, Bcl-2 and Bax in cancer cells. Real-time PCR was applied to detect miR-15b and miR-16 expression levels. Drug sensitivity was determined with MTT assay. Cell cloning efficiency was evaluated by Colony-forming assay. Apoptotic cells were detected with annexin V staining and flow cytometry.ResultsIn vitro drug sensitivity assay revealed that suppression of NDRG2 could sensitize Hela cells to cisplatin. Down-regulation of NDRG2 didn’t influence the colony-forming ability but promoted cisplatin-induced apoptosis of Hela cells. Inhibition of NDRG2 in Hela cells was accompanied by decreased Bcl-2 protein level. However, Bcl-2 mRNA level was not changed in Hela cells with down-regulation of NDRG2. Further study indicated that miR-15b and miR-16, two microRNAs targetting Bcl-2, were significantly up-regulated in NDRG2-suppressed Hela cells.ConclusionsThese data suggested that down-regulation of NDRG2 could enhance sensitivity of Hela cells to cisplatin through inhibiting Bcl-2 protein expression, which might be mediated by up-regulating miR-15b and miR-16.

Effects of PEMF exposure at different pulses on osteogenesis of MC3T3-E1 cells

OBJECTIVE Pulsed electromagnetic fields (PEMFs) were considered to be a factor which may affect osteogenesis of osteoblasts, but the effects were diverse with different PEMF parameters. The aim of the current study is to explore the effects of exposure to PEMFs at different pulse number on osteogenesis of osteoblasts. DESIGN The mouse osteoblast-like MC3T3-E1 cells were exposed to 0, 400 or 2800 pulses 400kV/m PEMF and the proliferation, differentiation and mineralization of cells were observed after PEMF exposure by the methods of MTT, biochemical measurement, real-time PCR and Alizarin Red assay. RESULTS Compared with 0 pulses groups, the growth curve, alkaline phosphatase (ALP) activity, mRNA level of osteocalcin (OCN) and mineralized nodule formation of MC3T3-E1 cells did not change after 400 pulses PEMF exposure, but decreased after 2800 pulses PEMF exposure. It suggested that under our experimental conditions, only 2800 pulses 400kV/m PEMF exposure can suppress the proliferation, differentiation and mineralization of MC3T3-E1 cells, but 400 pulses 400kV/m PEMF exposure cannot. CONCLUSIONS Pulse number is another involved parameter which may influence the effects of PEMF on osteogenesis of osteoblasts.

Combination Therapy with Metformin and Fenofibrate for Insulin Resistance in Obesity

This randomized controlled study investigated metformin and fenofibrate, compared with metformin alone, for the treatment of peripheral insulin resistance in patients with simple obesity with hyperinsulinaemia but not diabetes. Participants were randomized to receive metformin (500 mg orally three times daily) plus either fenofibrate (200 mg orally once daily; n = 44) or placebo (n = 43) for 6 months. Blood pressure, free fatty acids (FFA), body mass index (BMI), lipid and insulin levels were recorded pre- and post-treatment. β-Cell function and insulin resistance were measured by the homeostasis model assessment for insulin resistance (HOMA-IR) index. Both groups showed significant decreases in blood pressure, FFA, BMI and HOMA-IR relative to baseline. In addition, combined metformin and fenofibrate therapy showed significantly decreased fasting and postmeal insulin levels relative to baseline and relative to the placebo group. Both treatments were well tolerated. Metformin and fenofibrate can increase insulin sensitivity and recover β-cell function in patients with simple obesity accompanied by insulin resistance.