Neuron-glial antigen 2 overexpression in hepatocellular carcinoma predicts poor prognosis

AIM:To investigate whether neuron-glial antigen 2(NG2) could be an effective prognostic marker in hepatocellular carcinoma(HCC).METHODS:NG2 expression was semi-quantitatively scored from the immunohistochemistry(IHC) data based on the number of positive cells and the staining intensity.A total of 132 HCC specimens and 96 adjacent noncancerous tissue samples were analyzed by IHC for NG2 protein expression.To confirm the NG2 expression levels observed by IHC,we measured NG2 expression in 30 randomly selected tumor and adjacent noncancerous tissue samples by quantitative real-time polymerase chain reaction and Western blot.The correlations between NG2 protein expression and the clinicopathological features of HCC patients were analyzed using the χ2 test.To assess the prognostic value of NG2 for HCC,the association between NG2 expression and survival was analyzed using the KaplanMeier method with the log-rank test.To further evaluate the prognostic value of NG2 expression,a Cox multivariate proportional hazards regression analysis was performed with all the variables to derive risk estimates related to disease-free and overall survival and to control for confounders.RESULTS:High NG2 expression was observed in significantly more primary tumor samples(63.6%; 84/132) compared with the adjacent noncancerous tissue samples(28.1%; 27/96)(P < 0.0001).Moreover,high NG2 protein expression was closely associated with tumor differentiation(χ2 = 9.436,P = 0.0089),recurrence(χ2 = 5.769,P = 0.0163),tumor-nodemetastasis(TNM) stage(χ2 = 8.976,P = 0.0027),and invasion(χ2 = 5.476,P = 0.0193).However,no significant relationship was observed between NG2 protein expression in HCC and other parameters,such as age,sex,tumor size,serum alpha fetoprotein(AFP),tumor number,or tumor capsule.The log-rank test indicated a significant difference in the overall survival of HCC patients with high NG2 expression compared with those with low NG2 expression(29.2% vs 9.5%,P < 0.001).Moreover,NG2 expression in HCC tissue significantly correlated with disease-free survival(15.2% vs 6.7%,P < 0.001).Multivariate analysis showed that NG2 expression(HR = 2.035,P = 0.002),serum AFP(HR = 1.903,P = 0.003),TNM stage(HR = 2.039,P = 0.001),and portal vein invasion(HR = 1.938,P = 0.002) were independent prognostic indicators for OS in HCC patients.Furthermore,NG2 expression(HR = 1.974,P = 0.003),serum AFP(HR = 1.767,P = 0.008),TNM stage(HR = 2.078,P = 0.001),tumor capsule(HR = 0.652,P = 0.045),and portal vein invasion(HR = 1.941,P = 0.002) were independent prognostic indicators for DFS in HCC patients.CONCLUSION:The up-regulation of NG2 is associated with poor prognosis in HCC.Therefore,NG2 could be useful as an additional prognostic marker to increase the resolution of traditional approaches.

神经胶质抗原2胶质细胞与中枢神经系统疾病的研究进展

神经胶质抗原2(NG2)胶质细胞是兼具神经元和胶质细胞特性的特殊细胞,其细胞表面特异性表达NG2硫酸软骨素蛋白多糖。NG2胶质细胞是脑内区别于神经元、成熟少突胶质细胞、星形胶质细胞和小胶质细胞的细胞亚群,广泛存在于发育和成年的哺乳动物中枢神经系统(CNS)中,参与调节CNS的重建、神经网络、轴突生长和多种CNS疾病。CNS失衡在帕金森病、阿尔茨海默病等神经系统疾病的发病机制中发挥重要作用。因此,深入研究NG2与CNS疾病的相关性,可以为疾病的治疗提供新思路。

Beta-nerve growth factor gene therapy alleviates pyridoxine-induced neuropathic damage by increasing doublecortin and tyrosine kinase A in the dorsal root ganglion

Beta-nerve growth factor(β-NGF) is known to be a major leading cause of neuronal plasticity. To identify the possible action mechanisms of β-NGF gene therapy for sciatic nerve recovery, experimental dogs were randomly divided into control, pyridoxine, and pyridoxine + β-NGF groups. We observed chronological changes of morphology in the dorsal root ganglia in response to pyridoxine toxicity based on cresyl violet staining. The number of large neurons positive for cresyl violet was dramatically decreased after pyridoxine intoxication for 7 days in the dorsal root ganglia and the neuron number was gradually increased after pyridoxine withdrawal. In addition, we also investigated the effects of β-NGF gene therapy on neuronal plasticity in pyridoxine-induced neuropathic dogs. To accomplish this, tyrosine kinase receptor A(TrkA), βIII-tubulin and doublecortin(DCX) immunohistochemical staining was performed at 3 days after the last pyridoxine treatment. TrkA-immunoreactive neurons were dramatically decreased in the pyridoxine group compared to the control group, but strong TrkA immunoreactivity was observed in the small-sized dorsal root ganglia in this group. TrkA immunoreactivity in the dorsal root ganglia was similar between β-NGF and control groups. The numbers of βIII-tubulin-and DCX-immunoreactive cells decreased significantly in the pyridoxine group compared to the control group. However, the reduction of βIII-tubulin-and DCX-immunoreactive cells in the dorsal root ganglia in the β-NGF group was significantly ameliorated than that in the pyridoxine group. These results indicate that β-NGF gene therapy is a powerful treatment of pyridoxine-induced neuropathic damage by increasing the TrkA and DCX levels in the dorsal root ganglia. The experimental protocol was approved by the Institutional Animal Care and Use Committee(IACUC) of Seoul National University, South Korea(approval No. SNU-060623-1, SNU-091009-1) on June 23, 2006 and October 9, 2009, respectively.

Mechanisms responsible for the inhibitory effects of epothilone B on scar formation after spinal cord injury

Scar formation after spinal cord injury is regarded as an obstacle to axonal regeneration and functional recovery.Epothilone B provides moderate microtubule stabilization and is mainly used for anti-tumor therapy.It also reduces scar tissue formation and promotes axonal regeneration after spinal cord injury.The aim of the present study was to investigate the effect and mechanism of the microtubule-stabilizing reagent epothilone B in decreasing fibrotic scarring through its action on pericytes after spinal cord injury.A rat model of spinal cord injury was established via dorsal complete transection at the T10 vertebra.The rats received an intraperitoneal injection of epothilone B（0.75 mg/kg） at 1 and 15 days post-injury in the epothilone B group or normal saline in the vehicle group.Neuron-glial antigen 2,platelet-derived growth factor receptor β,and fibronectin protein expression were dramatically lower in the epothilone B group than in the vehicle group,but β-tubulin protein expression was greater.Glial fibrillary acidic protein at the injury site was not affected by epothilone B treatment.The Basso,Beattie,and Bresnahan locomotor scores were significantly higher in the epothilone B group than in the vehicle group.The results of this study demonstrated that epothilone B reduced the number of pericytes,inhibited extracellular matrix formation,and suppressed scar formation after spinal cord injury.