Lijuan Wang

Overproduction of Cyclin D1 is dependent on activated mTORC1 signal in nasopharyngeal carcinoma: Implication for therapy

Activated mTOR was implicated to play a role in the carcinogenesis of nasopharyngeal carcinoma (NPC). However, the mechanism of activated mTOR/Complex1(mTORC1) signaling pathway in NPC development has not been well established. In this study, we correlated the expression of mTORC1 signal molecules and Cyclin D1 in NPC. We also investigated the effect of blocking mTORC1 signal with rapamycin and mTOR siRNA on Cyclin D1 expression in CNE-2 cells, as well as cell apoptosis and viability. We found a positive association of mTORC1 signal molecules and Cyclin D1 in NPC. Also, we found blockage mTORC1 inhibited Cyclin D1 expression in CNE-2 cells and enhanced cell apoptosis. Our results suggested that mTORC1 signal pathway might be a potential target for NPC therapy.

The role of p38MAPK signal pathway in the neuroprotective mechanism of limb postconditioning against rat cerebral ischemia/reperfusion injury

It has been reported that remote ischemic postconditioning was able to protect from a harmful ischemia occurring in brain. In the present study, we investigated the role of p38 MAPK signal pathway in the process of neuroprotection and anti-apoptosis following remote limb ischemic postconditioning on rat focal cerebral ischemia/reperfusion (I/R) model. Male Sprague-Dawley rats were divided randomly into four groups: the sham-operated group, I/R group, limb ischemic postconditioning (LPostC) group, and LPostC+SB203580 (p38 MAPK inhibitor) group. Focal ischemia was induced by transient middle cerebral artery occlusion. Limb ischemic postconditioning was implemented by brief cycles of femoral artery occlusion. At 24h after modeling, we analyzed the neurological deficit score, assessed the cerebral tissue morphology by H-E staining, and evaluated neuronal apoptosis by TUNEL staining. The protein expression levels of p-p38 or p-ATF2 (phospho-activating transcription factor 2) in the penumbra region were detected by western blotting or immunohistochemical staining. Our findings revealed that LPostC relieved cerebral ischemia/reperfusion injury by decreasing neurological score, improving neuronal morphological changes in the ischemic penumbra area, and reducing neuronal apoptosis. In addition, LPostC or LPostC+SB203580 attenuated the increase in p-p38 and p-ATF2 levels in ischemia/reperfusion brain tissue. These results indicate that the protective effects of LPostC against cerebral I/R injury may be related to the attenuation of neuronal apoptosis and the suppression of p38 MAPK-ATF2 pathway.

Altered Resting-State Functional Connectivity of the Striatum in Parkinson's Disease after Levodopa Administration.

Background Despite improvement in motor symptoms, the effect of dopaminergic medications on cognition in patients with Parkinson’s disease (PD) is less clear. The purpose of this study was to reveal levodopa-induced acute changes in the functional connectivity of the striatum in patients with PD compared with matched untreated patients and healthy volunteers. Methods Twenty-two patients with PD underwent functional magnetic resonance imaging both ON and OFF dopamine-replacement therapy on two consecutive days. Twenty-eight normal aging volunteers also did them without taking in levodopa. Three caudate seeds and two putamen seeds were selected to calculate functional connectivity intensity. Results Motor symptoms measured by UPDRS were significantly worse in PD OFF than PD ON. Decreased functional connectivity in PD OFF compared to controls was detected in the following seed regions: dorsal caudate, ventral putamen and dorsal putamen. Increases in connectivity in PD ON compared to controls were found in the primary and supplementary motor areas and the associative prefrontal and parietal regions, while decreases in anterior cingulate, ventromedial prefrontal cortex, and parahippocampal gyrus. For the ventral striatal seeds, decreased connectivity in PD ON compared to PD OFF was found in the ventromedial prefrontal and orbitofrontal regions, dorsolateral prefrontal regions. For the dorsal striatal seeds, increased connectivity in PD ON compared to PD OFF was observed in the primary and secondary motor areas. Conclusion Our results suggest that levodopa significantly changes the motor and cognitive networks of the cortico-striatal pathways. This knowledge will lead clinicians to survey a broader range of symptoms in determining optimal therapy.

MCP-1 and CCR2 gene polymorphisms in Parkinson’s disease in a Han Chinese cohort

Monocyte chemoattractant protein-1 (MCP-1) and its receptor CC chemokine receptor-2 (CCR2) play important roles in neuroinflammation and they have been shown to be involved in Parkinson’s disease (PD) pathogenesis. In addition, several studies have suggested a role for the MCP-1 and CCR2 genotypes in cognitive impairment and depression, which are common non-motor symptoms in PD patients. In this study, a cohort of 521 PD patients and 556 cases of healthy controls were recruited to investigate the association between the MCP-1 2518A/G (rs1064211) and CCR2 V64I (rs1799864) gene polymorphisms and PD risk in the Chinese population. We also analyze the influence of these genotypes on the cognitive function and depression in PD patients by comparing Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Wechsler Adult Intelligence Scale-Chinese Revision (WAIS-RC), Wechsler Memory Scale-Chinese Revision (WMS-RC) and Hamilton Depression Rating Scale (HAMD) ratings in 217 PD patients. Our results showed no significant differences in the genotype frequency between the PD group and the control group (Pxa0>xa00.05). In addition, we also failed to find an influence of the MCP-1 and CCR2 genotypes on MMSE scores, MoCA scores, WAIS-RC scores, WMS-RC scores and HAMD scores in PD patients (Pxa0>xa00.05). The MCP-1 and CCR2 gene polymorphisms may not be genetic risk factors for PD in the Han Chinese population, and they do not appear to influence cognitive function and depression in PD patients.

RIT2 polymorphism is associated with Parkinson's disease in a Han Chinese population.

Recently, a meta-analysis including 5 large genome-wide association studies has identified rs12456492 variant of RIT2 gene as a novel risk locus for Parkinsons disease (PD) in Caucasian populations. However, the association between RIT2 polymorphism and PD risk has not been positively replicated in Asian population yet. We detected the genotypes of rs12456492 in 524 PD patients and 521 control subjects from a Han Chinese population. The allele and genotype distribution of rs12456492 variant were significantly different between PD patients and controls (allele p = 0.001, genotype p = 0.002). Logistic regression analysis showed that the G-carrying genotype (AG + GG) individuals exhibited a nearly 1.4-fold increased risk for PD compared with the AA genotype carriers (OR = 1.390; 95% confidence interval = 1.079-1.791; p = 0.011). Our data support that the carriage of G allele of rs12456492 variant of RIT2 gene significantly increases the risk for PD in Han Chinese population, suggesting a potential role of RIT2 in the etiology of PD.

Neuroprotection by platelet-activating factor acetylhydrolase in a mouse model of transient cerebral ischemia

Neuronal damage after transient cerebral ischemia is exacerbated by signaling pathways involving activated platelet-activating factor (PAF) and ameliorated by PAF-acetylhydrolase (PAF-AH); but whether cerebral neurons can be rescued by human recombinant PAF-AH (rPAF-AH) remains unknown. Adult male mice underwent a 60 min middle cerebral artery occlusion (MCAO) and reperfusion for 24h. Then, the mice received intravenous tail injections with different drugs. Neurological behavioral function was evaluated by Bedersons test, and cerebral infarction volume was assessed with tetrazolium chloride (TTC) staining. mRNA and protein expression levels of matrix metalloproteinase-2 (MMP-2, collagenase-1), MMP-9 (gelatinase-B), and vascular endothelial growth factor (VEGF) were determined by quantitative real-time PCR (RT-PCR) and western blot analysis, respectively. Compared with the vehicle group, rPAF-AH significantly improved sensorimotor function (42%, P=0.0001). The volume of non-infarcted brain tissue was increased by the rPAF-AH treatment (16.3±4.6% vs. 46.0±10.3%, respectively). rPAF-AH significantly reduced mRNA and protein levels of MMP-2 and MMP-9, but increased the mRNA (P<0.001) and protein levels (P<0.01) of VEGF. These results demonstrate that rPAF-AH provides neuroprotection against ischemic injury. Neuroprotection might be induced not only by decrease in MMP-2 and MMP-9 expression, but also by increased VEGF expression.

Diffusion Kurtosis Imaging of Substantia Nigra Is a Sensitive Method for Early Diagnosis and Disease Evaluation in Parkinson's Disease

Background. To diagnose Parkinson disease (PD) in an early stage and accurately evaluate severity, it is important to develop a sensitive method for detecting structural changes in the substantia nigra (SN). Method. Seventy-two untreated patients with early PD and 72 healthy controls underwent diffusion tensor and diffusion kurtosis imaging. Regions of interest were drawn in the rostral, middle, and caudal SN by two blinded and independent raters. Mean kurtosis (MK) and fractional anisotropy in the SN were compared between the groups. Receiver operating characteristic (ROC) and Spearman correlation analyses were used to compare the diagnostic accuracy and correlate imaging findings with Hoehn-Yahr (H-Y) staging and part III of the Unified Parkinsons Disease Rating Scale (UPDRS-III). Result. MK in the SN was increased significantly in PD patients compared with healthy controls. The area under the ROC curve was 0.976 for MK in the SN (sensitivity, 0.944; specificity, 0.917). MK in the SN had a positive correlation with H-Y staging and UPDRS-III scores. Conclusion. Diffusion kurtosis imaging is a sensitive method for PD diagnosis and severity evaluation. MK in the SN is a potential biomarker for imaging studies of early PD that can be widely used in clinic.

Down-Regulation of Platelet-Activating Factor Receptor Gene Expression During Focal Reversible Cerebral Ischemia in Rats

Platelet-activating factor (PAF) is an endogenous potent phospholipid mediator in stroke and related to the post-ischemic brain damage. The aim of this study was to investigate the regulation and mechanisms of PAF receptor gene expression in the perifocal regions of cerebral infarction after middle cerebral artery occlusion/reperfusion. Sixty mature Wistar rats were randomly divided into 12 groups: sham-operated control group, simple ischemia 90xa0min group, 6, 12, 18xa0h, 1 day (1xa0d), 2, 3, 4, 5, 6, 7xa0d reperfusion groups. After the right middle cerebral artery occluded, the rats were suffered from ischemia for 90xa0min, and then reperfusion was allowed for different time courses. Reverse transcription-polymerase chain reaction (RT-PCR) and radioimmunoassay were applied to evaluate the PAF receptor messenger RNA (mRNA) expression and PAF levels in the perifocal regions of cerebral infarction respectively. RT-PCR analysis revealed that PAF receptor mRNA was 0.95xa0±xa00.15 in control group. However, following ischemia-reperfusion, the levels of PAF receptor mRNA progressively decreased until 2xa0d of reperfusion (0.54xa0±xa00.10), then returned to control group’s levels gradually. Compared with the control group’s (582xa0±xa072xa0pg/g wet weight), the PAF concentrations of simple ischemic and 6, 12, 18xa0h, 1, 2xa0d reperfusion group were significantly higher than that of any other groups. These results indicate that PAF receptor gene expression may be subject to down-regulation in the perifocal regions of cerebral infarction after cerebral ischemia-reperfusion and relative to the increase of endogenous PAF concentrations.

Effect of simvastatin on the expression of farnesoid X receptor in diabetic animal models of altered glucose homeostasis.

Background Statin therapy has affected glucose homoeostasis of type 2 diabetes patients, which could be related with bile acids metabolism. Whether bile acid metabolism and the expression of farnesoid X receptor (FXR), liver X receptor‐&agr; (LXR‐&agr;) and sterol regulatory element‐binding protein (Srebp)‐1c is regulated by hyperglycemia, or whether simvastatin therapy led to higher glucose is related with down‐regulated expression of FXR in diabetic rats remained unclear. Methods Forty male Wistar rats were randomly divided into four groups: normal control rats, insulin resistance rats, diabetic model rats, and the late simvastatin induced diabetic rats. Normal control rats were fed with standard diet, others were fed with high‐fat diet. Diabetic model rats were induced by a single intraperitoneal injection of streptozotocin (STZ). The late simvastatin induced diabetic rats started simvastatin administration after STZ induced diabetic model rats. Characteristics of fasting blood glucose (FPG), lipid files and total bile acids (TBAs) were measured and the oral glucose tolerance test (OGTT) was performed after overnight fasting at the eighth weekend. RNA and protein levels of FXR, LXR‐&agr; and Srebp‐1c were tested by Western blotting and reverse transcription polymerase chain reaction (RT‐PCR). Results The insulin resistance rats showed higher glucose, lipid files and lower expression of FXR compared with normal control rats (P >0.05). The diabetic model rats showed significantly higher glucose, lipid files, TBA and lower expression of FXR compared with insulin resistance rats (P <0.05). The late simvastatin induced diabetic rats displayed higher glucose and TBA and lower expression of FXR compared with diabetic model rats (P <0.05). Conclusions Changes in bile acid homeostasis, including the alterations of bile acid levels and bile acid receptors, are either a cause or a consequence of the metabolic disturbances observed during diabetic models. Statin therapy induced hyperglycemia may be related with FXR, SHP, LXR‐&agr; and Srebp‐1 pathways.

Catechol-O-methyltransferase Val158Met polymorphism influences prefrontal executive function in early Parkinson's disease

OBJECTIVEnThe catechol-O-methyltransferase (COMT) Val158Met polymorphism has been proposed to be associated with increased risk of Parkinsons disease (PD) and have a specific impact on dopamine-mediated prefrontal executive function in an inverted-U curve manner. We explored the influence of this genetic polymorphism on prefrontal executive function in a well-established Chinese cohort of early PD patients with no current or past history of motor fluctuations or dyskinesias.nnnMETHODSnCognitive functions were assessed in 250 patients with early PD using Wechsler Adult Intelligence Scale-Chinese Revision (WAIS-RC) and Wechsler Memory Scale-Chinese Revision (WMS-RC). These patients and 300 healthy controls were subsequently genotyped for the COMT gene Val158Met polymorphism. We employed analysis of covariance (ANCOVA) and a stratified analysis to determine the associations between the COMT Val158Met genotype and cognitive functions.nnnRESULTSnThe COMT Val158Met allele frequency and genotype distributions showed no statistically significant differences between PD patients and controls. However, patients with met/met genotype performed significantly worse on WAIS-RC similarities, a measure of executive function, compared to individuals with val/val genotype. Subsequent ANCOVA analysis revealed that COMT genotype interacted with sex and daily levodopa equivalent dose (LED) to influence executive function. Further stratified analysis showed that the lower-activity COMT met/met genotype has a detrimental effect on executive function among women.nnnCONCLUSIONSnOur results demonstrate that COMT Val158Met polymorphism is probably not associated with increased risk of PD, but has an effect on prefrontal executive function interacting with gender and dopaminergic medication.