Inhibition of PTPN21 has antitumor effects in glioma by restraining the EGFR/PI3K/AKT pathway.

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) has been recognised as a new tumour-associated protein that is implicated in diverse tumours. However, the correlation between PTPN21 and glioma remains unaddressed. This investigation focused on the relevance of PTPN21 in glioma. The Cancer Genome Atlas (TCGA) analysis identified PTPN21 as being up-regulated in glioma tissue. The elevation of PTP21 in glioma was validated by evaluating clinical specimen. Kaplan-Meier plot analysis revealed that a high PTPN21 level predicted poor survival rate in glioma patient. Silencing of PTPN21 produced remarkable anticancer effects in glioma cells including proliferation inhibition, cell cycle arrest, metastasis suppression and enhanced chemosensitivity. Mechanistic studies uncovered that PTPN21 contributes to mediation of the phosphatidyl-inositole-3 kinase (PI3K)/AKT pathway via the regulation of epidermal growth factor receptor (EGFR). Restraint of EGFR diminished PTPN21 overexpression-induced promoting effect on PI3K/AKT pathway. Reactivation of AKT reversed PTPN21 silencing-evoked antitumor effect. The tumorigenic potential of PTPN21-silenced glioma cells in vivo was markedly compromised. In summary, this study demonstrates that silencing of PTPN21 produces remarkable anticancer effects in glioma by restraining the EGFR/PI3K/AKT pathway.

Inhibitory effects of low decibel infrasound on the cardiac fibroblasts and the involved mechanism.

INTRODUCTION: Infrasound is a mechanical vibration wave with frequency between 0.0001 and 20 Hz. It has been established that infrasound of 120 dB or stronger is dangerous to humans. However, the biological effects of low decibel infrasound are largely unknown. The purpose of this study was to investigate the effects of low decibel infrasound on the cardiac fibroblasts. MATERIALS AND METHODS: The cardiac fibroblasts were isolated and cultured from Sprague-Dawley rats. The cultured cells were assigned into the following four groups: control group, angiotensin II (Ang II) group, infrasound group, and Ang II+infrasound group. The cell proliferation and collagen synthesis rates were evaluated by means of [3H]-thymidine and [3H]-proline incorporation, respectively. The levels of TGF-ß were determined by enzyme-linked immunosorbent assay. Moreover, RNAi approaches were used for the analysis of the biological functions of miR-29a, and the phosphorylation status of Smad3 was detected using western blotting analysis. RESULTS: The results showed that low decibel infrasound significantly alleviated Ang II-induced enhancement of cell proliferation and collagen synthesis. DISCUSSION: Compared with the control, Ang II markedly decreased the expression of miR-29a levels and increased the secretion of TGF-ß and phosphorylation of Smad3, which was partly reversed by the treatment with low decibel infrasound. Importantly, knockdown of miR-29a diminished the effects of infrasound on the cardiac fibroblasts. In conclusion, low decibel infrasound inhibits Ang II-stimulated cardiac fibroblasts via miR-29a targeting TGF-ß/Smad3 signaling.

Antioxidant catalase rescues against high fat diet-induced cardiac dysfunction via an IKKß-AMPK-dependent regulation of autophagy.

Autophagy, a conservative degradation process for long-lived and damaged proteins, participates in a variety of biological processes including obesity. However, the precise mechanism of action behind obesity-induced changes in autophagy still remains elusive. This study was designed to examine the role of the antioxidant catalase in high fat diet-induced changes in cardiac geometry and function as well as the underlying mechanism of action involved with a focus on autophagy. Wild-type (WT) and transgenic mice with cardiac overexpression of catalase were fed low or high fat diet for 20 weeks prior to assessment of myocardial geometry and function. High fat diet intake triggered obesity, hyperinsulinemia, and hypertriglyceridemia, the effects of which were unaffected by catalase transgene. Myocardial geometry and function were compromised with fat diet intake as manifested by cardiac hypertrophy, enlarged left ventricular end systolic and diastolic diameters, fractional shortening, cardiomyocyte contractile capacity and intracellular Ca²âº mishandling, the effects of which were ameliorated by catalase. High fat diet intake promoted reactive oxygen species production and suppressed autophagy in the heart, the effects of which were attenuated by catalase. High fat diet intake dampened phosphorylation of inhibitor kappa B kinase ß(IKKß), AMP-activated protein kinase (AMPK) and tuberous sclerosis 2 (TSC2) while promoting phosphorylation of mTOR, the effects of which were ablated by catalase. In vitro study revealed that palmitic acid compromised cardiomyocyte autophagy and contractile function in a manner reminiscent of fat diet intake, the effect of which was significantly alleviated by inhibition of IKKß, activation of AMPK and induction of autophagy. Taken together, our data revealed that the antioxidant catalase counteracts against high fat diet-induced cardiac geometric and functional anomalies possibly via an IKKß-AMPK-dependent restoration of myocardial autophagy. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.

Gas1 up-regulation is inducible and contributes to cell apoptosis in reactive astrocytes in the substantia nigra of LPS and MPTP models.

BACKGROUND: Reactive astrogliosis is a remarkable pathogenetic hallmark of the brains of Parkinson's disease (PD) patients, but its progressive fate and regulation mechanisms are poorly understood. In this study, growth arrest specific 1 (Gas1), a tumor growth suppressor oncogene, was identified as a novel modulator of the cell apoptosis of reactive astrocytes in primary culture and the injured substantia nigra. METHODS: Animal models and cell cultures were utilized in the present study. Lipopolysaccharide (LPS)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated animal models were used to detect Gas1 expression in the brain via immunohistochemistry and western blot. Cell cultures were performed to analyze Gas1 functions in the viability and apoptosis of reactive astrocytes and SH-SY5Y cells by double labeling, CCK-8, LDH, TUNEL, flow cytometry, and siRNA knockdown methods. RESULTS: Gas1 expressions were significantly elevated in the majority of the reactive astrocytes of the brains with LPS or MPTP insults. In the injured substantia nigras, GFAP-positive astrocytes exhibited higher levels of cleaved caspase-3. In cell culture, the up-regulated Gas1 expression induced apoptosis of reactive astrocytes that were insulted by LPS in combination with interferon-γ and tumor necrosis factor-a. This effect was confirmed through siRNA knockdown of Gas1 gene expression. Finally and interestingly, the potential underlying signaling pathways were evidently related to an increase in the Bax/Bcl-2 ratio, the abundant generation of reactive oxygen species and the activation of cleaved caspase-3. CONCLUSIONS: This study demonstrated that the up-regulation of inducible Gas1 contributed to the apoptosis of reactive astrocytes in the injured nigra. Gas1 signaling may function as a novel regulator of astrogliosis and is thus a potential intervention target for inflammatory events in PD conditions.

Associations between personality changes and nucleus accumbens ablation in opioid addicts.

AIM: It has been reported that nucleus accumbens (NAc) lesions can help to prevent relapse in opioid addicts. This article aimed to investigate associations between personality changes and NAc lesions. METHODS: The surgery group consisted of 78 patients who had received bilateral stereotactic lesions of the NAc to treat opioid addiction. Seventy two non-surgery opioid addicts were appropriately paired with the patients of the surgery group as the non-surgery group. All participants were interviewed in person and received urine tests, naloxone provocative tests and hair tests to determine the prevalence of relapse. Eysenck personality questionnaire (EPQ) and the health survey questionnaire (SF-36) were employed to assess personality and functional health, respectively. RESULTS: In the surgery group, 30 participants relapsed, and the non-relapse rate was 61.5% (48/78). Compared with the Chinese normative data, the neuroticism (N) and psychoticism (P) dimensions of the EPQ in the non-surgery group were significantly higher, whereas the lie (L) dimension was significantly lower. There was no significant difference in all dimensions of the EPQ between the surgery group and the Chinese normative data. The N dimension in the relapse group and the L dimension in the surgery group were significantly lower than those of the non-surgery group. The P dimension in the relapse group was significantly higher than that of the non-relapse group. The extraversion (E) dimension was relatively stable between these groups. CONCLUSION: Although the influence of other factors cannot be excluded, it is apparent that surgically induced NAc lesions are associated with lower P and N dimensions for opioid addicts, and a higher P dimension is associated with a tendency to relapse.

The protective effects of inosine against chemical hypoxia on cultured rat oligodendrocytes.

Inosine is a purine nucleoside and is considered protective to neural cells including neurons and astrocytes against hypoxic injury. However, whether oligodendrocytes (OLs) could also be protected from hypoxia by inosine is not known. Here we investigated the effects of inosine on primarily cultured rat OLs injured by rotenone-mediated chemical hypoxia, and the mechanisms of the effects using ATP assay, MTT assay, PI-Hoechst staining, TUNEL, and immunocytochemistry. Results showed that rotenone exposure for 24 h caused cell death and impaired viability in both immature and mature OLs, while pretreatment of 10 mM inosine 30 min before rotenone administration significantly reduced cell death and improved the viability of OLs. The same concentration of inosine given 120 min after rotenone exposure also improved viability of injured mature OLs. Immunocytochemistry for nitrotyrosine and cellular ATP content examination indicated that inosine may protect OLs by providing ATP and scavenging peroxynitrite for cells. In addition, immature OLs were more susceptible to hypoxia than mature OLs; and at the similar degree of injury, inosine protected immature and mature OLs differently. Quantitative real-time PCR revealed that expression of adenosine receptors was different between these two stages of OLs. These data suggest that inosine protect OLs from hypoxic injury as an antioxidant and ATP provider, and the protective effects of inosine on OLs vary with cell differentiation, possibly due to the adenosine receptors expression profile. As OLs form myelin in the central nervous system, inosine could be used as a promising drug to treat demyelination-involved disorders.

[Toxic effects of Vitamin C combined with temozolomide on glioma cells and its mechanism].

Objective: To investigate the toxic effects of vitamin C (VC) combined with temozolomide (TMZ) on gliomas and its mechanism. Methods: Human glioma cells BMG-1 and SHG44 cells were cultured in vitro, specifically divided into control group (without VC and TMZ), TMZ group (0.2 mmol/L), VC (0.5 mmol/L)+TMZ(0.2 mmol/L) group and TMZ(0.2 mmol/L TMZ)+U0126(10 µmol/L)group, each experiment was repeated three times. Cell survival rate was detected by MTT assay; Cell apoptosis was detected by flow cytometry and Annexin V-FITC/PI staining; Reactive oxygen species (ROS) levels were detected by ROS detection kit, and Western blot was used to detect the expression levels of proteins related to apoptosis, autophagy and ERK pathway. Results: Compared with the control group, the survival rate of glioma cells in the TMZ group was decreased significantly(P＜0.05). Compared with the TMZ group, the survival rate of glioma cells in the VC+TMZ group was decreased significantly(P＜0.01), the cell apoptosis rate was increased, and the expressions of Bax, Cleaved caspase-3 and Cleaved PARP protein were increased, while the expression of Bcl-2 was decreased. The ROS level and autophagy rate were decreased, while the expression of LC3-II/LC3-1 was decreased, and the expression of p62 was increased in the VC+TMZ group (all P＜0.05). At the same time, VC combined with TMZ decreased the expression level of p-ERK1/2-related protein in BMG-1 and SHG44 cells, and increased the apoptosis rate (P＜0.05). Conclusion: VC combined with temozolomide can enhance the toxicity of glioma cells. This effect is to promote apoptosis and inhibit temozolomide-mediated autophagy through the regulation of the ERK signaling pathway.

Reactive astrocytes increase expression of proNGF in the mouse model of contused spinal cord injury.

Astrocytes are major glial cells critically in maintaining stability of the central nervous system and functional activation of astrocytes occurs rapidly in various diseased or traumatic events. We are interested in functional changes of astrocytes during the spinal cord injury, and studied expression of nerve growth factor (NGF) in activated astrocytes by mouse model of contused spinal cord injury and cell culture experiment. It revealed that the spinal cord injury resulted in apparent activation of astrocytes and microglial cells and decreased BMS scores. A larger number of astrocytes showed immunoreactivity to proNGF in the injured spinal cord areas, and proNGF expression increased and remained high level at 7 to 14dpi, which was coincided with upregulation of glial fibrillary acidic protein. The proNGF was clearly localized in both exosome-like vesicles and cytoplasm of astrocytes in culture. Electron microscopy confirmed exosome-like vesicles with proNGF-immunoreactivity in diameter sizes of 50-100 nm. Finally, cell culture with lipopolysaccharide (LPS) experiment indicated increasing expression and release of proNGF in the astrocytes with LPS exposure. This study demonstrated that reactive astrocytes increased proNGF expression after spinal cord injury, also suggesting involvement of exosome-like proNGF transport or release in triggering neuronal apoptosis and aggravating progression of spinal cord injury.

Nucleus accumbens surgery for addiction.

BACKGROUND: Opiate addiction remains intractable in a large percentage of patients, and relapse is the biggest hurdle to recovery because of psychological dependence. Multiple studies identify a central role of the nucleus accumbens (NAc) in addiction; several studies note decreased addictive behavior after interventions in this area. METHODS: Based on animal experiments, our institute started the clinical trial for the treatment of drug addicts' psychological dependence by making lesions in the bilateral NAc with stereotactic surgery from July 2000. RESULTS: The short-term outcomes were encouraging and triggered rapid application of this treatment in China from 2003 to 2004. However, lack of long-term outcomes and controversy eventually led to halting the surgery for addiction by the Ministry of Health of China in November 2004 and a nationwide survey about it later. Our institute had performed this surgery in 272 patients with severe heroin addiction. The follow-up study showed that the 5-year nonrelapse rate was 58% and the quality of life was significantly improved. Patients had several kinds of side effects, but the incidence rate was relatively low. The patients gradually recovered more than 5 years after the surgery. The side effects did not severely influence an individual's life or work. Nationwide surgery showed that the nonrelapse rate was 50% in the sample of 150 cases, from 1167 patients overall who underwent stereotactic surgery in China. CONCLUSIONS: Although sometimes accompanied by neuropsychological adverse events, stereotactic ablation of NAc may effectively treat opiate addiction. Lesion location has a significant impact on treatment efficacy and requires further study. Because ablation is irreversible, the NAc surgery for addiction should be performed with cautiousness, and deep brain stimulation (DBS) is an ideal alternative.

Vasonatrin peptide, a novel protector of dopaminergic neurons against the injuries induced by n-methyl-4-phenylpyridiniums.

Vasonatrin peptide (VNP), a novel manmade natriuretic peptide, is known as a cardiovascular active substance. However, its neuroeffects are largely unknown. Here, cultured dopaminergic neurons from ventral mesencephalon of mouse were exposed to N-methyl-4-phenylpyridinium (MPP(+)), and the effects of VNP on the neurotoxicity of MPP(+) were investigated. As a result, MPP(+) caused injuries in the dopaminergic neurons. VNP significantly reduced the cytotoxicity of MPP(+) by increasing axon number and length of dopaminergic neurons, and by enhancing the cell viability. Also, the MPP(+)-induced depolymerization of ß-Tubulin III was attenuated by the treatment of VNP. In addition, VNP significantly increased the intracellular levels of cGMP. These effects of VNP were mimicked by 8-br-cGMP (a cell-permeable analog of cGMP), whereas inhibited by HS-142-1 (the antagonist of the particulate guanylyl cyclase-coupled natriuretic peptide receptors), or KT-5823 (a cGMP-dependent protein kinase inhibitor). Taken together, VNP attenuates the neurotoxicity of MPP(+) via guanylyl cyclase-coupled NPR/cGMP/PKG pathway, indicating that VNP might be a new effective reagent in the treatment of neuron degeneration of dopaminergic neurons in Parkinson's disease (PD).

[Condition optimization for degradation of chlorophenols using laccase from Amillariella mellea].

Crude laccase extracted from the Amillariella mellea fermentation broth was directly used to catalyze the degradation of 2,4-chlorophenol (2,4-DCP) and 2-chlorophenol (2-CP). The effects of reaction time, pH, temperature, chlorophenol concentration, and laccase dosage on the removal efficiency of chlorophenols were investigated. Optimal catalytic conditions for the degradation of chlorophenols were obtained and the degradation kinetics were analyzed. The results indicated that the crude laccase from Amillariella mellea was able to effectively degrade 2,4-DCP and 2-CP, with higher catalytic ability towards 2,4-DCP degradation. For 2,4-DCP degradation, the optimal temperature was 40 degrees C, the optimal substrate concentration was 75 mg x L(-1), the optimal enzyme dosage was 0. 1 U x mL(-1), and the optimal pH was 6.5. Under these conditions, the maximum degradation rate of 2,4-DCP reached > 97% after 10 h. For 2-DCP degradation, the optimal temperature was 50 degrees C, the optimal substrate concentration was 100 mg x L(-1), the optimal enzyme dosage was 0.1 U x mL(-1), and the optimal pH was 6. Under these conditions, the maximum degradation rate of 2-CP was over 93% after 10 h. The reaction process of laccase-catalyzed 2,4-DCP and 2-CP degradation obeyed the first-order kinetics equation. The laccase from Amillariella mellea was able to effectively degrade chlorophenols, indicating its potential application value in phenolic pollutant control and environmental protection.