胶质瘤中的异柠檬酸脱氢酶突变

胶质母细胞瘤的基因组突变分析中发现的异柠檬酸脱氢酶(isocitrate dehydrogenase,IDH)突变对胶质瘤的认识具有突破性意义.随后,在胶质瘤中发现了IDH1的R132碱基和IDH2的R172碱基突变.IDH1突变较多的发生在WHOⅡ～Ⅲ级胶质瘤和继发胶质母细胞瘤中.这种突变改变了异柠檬酸脱氢酶的结构,从而使将异柠檬酸转化为α-酮戊二酸的能力丧失,而获得将α-酮戊二酸转化为D-2-羟基戊二酸这一新的酶活性.在临床中,IDH1和IDH2突变已经显示对胶质瘤患者有诊断和预后意义.同时,现今也发展了一些检测方法.     

异柠檬酸脱氢酶1突变与人脑胶质瘤

癌症基因组学研究表明大部分WHO II级、III级胶质瘤及继发性胶质母细胞瘤(IV级)中,异柠檬酸脱氢酶1(isocitrate dehydrogenase 1,IDH1 )发生了新的点突变.IDH1突变发生在肿瘤早期,与预后关系密切.突变改变了IDH1酶活性,导致α-酮戊二酸和2-羟基戊二酸聚集.本文讨论了IDH1突...     

异柠檬酸脱氢酶1突变对胶质瘤细胞增殖的影响

目的:观察异柠檬酸脱氢酶1(IDH1)突变对人胶质瘤U87细胞增殖和蛋白激酶B(Akt)信号分子表达的影响。方法:分别用野生型(IDH1)和突变型(mut IDH1)重组慢病毒感染U87细胞,CCK8和平板克隆形成实验检验细胞增殖能力; Western Blot检测IDH1突变型基因和磷酸化Akt(p-Akt1/2/3)的蛋白表达量; TCGA数据库分析Akt在高级别胶质瘤(GBM)和低级别胶质瘤(LGG)中的表达情况;免疫组化检测Akt和p-Akt在GBM和LGG中的表达和定位。结果:IDH1和mut IDH1重组慢病毒成功感染U87细胞,CCK8实验表明mut IDH1组细胞活性减弱;平板克隆形成实验显示mut IDH1组细胞集落形成能力低于IDH1组; TCGA数据库分析显示,Akt在GBM和LGG中的表达高于正常脑组织;免疫组化显示Akt和p-Akt1/2/3在GBM和LGG中呈高表达; Western Blot显示mut IDH1组中Akt表达低于IDH1组。结论:IDH1突变能够减弱胶质瘤细胞的增殖,抑制Akt信号分子磷酸化活化。     

异柠檬酸脱氢酶1与突变体重组慢病毒的制备及表达

目的:制备异柠檬酸脱氢酶1野生型(IDH1)和R132H突变型(mut IDH1)基因重组慢病毒,感染人胶质瘤来源的细胞系U87细胞并观察目的基因的表达。方法:利用基因克隆技术构建IDH1和mut IDH1基因重组慢病毒载体p LVX-IDH1-mCMV-ZsGreen-PGK-Puro和p LVX-mutIDH1-mCMV-ZsGreen-PGK-Puro,转染293T细胞,进行慢病毒包装,获得慢病毒颗粒;慢病毒颗粒感染HEK293细胞,采用逐孔稀释滴度测定法测慢病毒滴度;IDH1和mut IDH1基因重组慢病毒感染U87细胞,观察感染效率,Western Blot检测IDH1和mut IDH1基因在U87细胞的表达。结果:成功制备IDH1和mut IDH1基因重组慢病毒颗粒,病毒滴度均为1.0×108TU/ml;感染U87细胞,Western Blot结果显示:IDH1组中IDH1蛋白水平高于mut IDH1组和空载体对照组; mut IDH1组中mut IDH1蛋白条带清晰,表达量高,IDH1组和对照组均不表达mut IDH1蛋白。结论:成功制备IDH1和mut IDH1基因重组...     

大鼠骨骼肌细胞异柠檬酸脱氢酶和琥珀酸脱氢酶活性在不同训练负荷时的变化

背景：异柠檬酸脱氢酶和琥珀酸脱氢酶是糖有氧氧化过程中的关键酶,不同训练方式和训练时间对骨骼肌异柠檬酸脱氢酶和琥珀酸脱氢酶活性影响的报道较少。 目的：探讨不同训练负荷条件对大鼠骨骼肌异柠檬酸脱氢酶和琥珀酸脱氢酶活性的影响。 方法：参照BEDFORD TG标准,建立大鼠有氧、无氧和有氧无氧交替运动跑台训练模型,正常饲养的大鼠作为对照。训练结束后,紫外分光光度计检测大鼠骨骼肌异柠檬酸脱氢酶和琥珀酸脱氢酶的活性。 结果与结论：有氧运动4,6周,大鼠骨骼肌异柠檬酸脱氢酶和琥珀酸脱氢酶活性均明显升高(P < 0.05);交替运动2周,异柠檬酸脱氢酶和琥珀酸脱氢酶活性增加(P < 0.05),运动至4,6周时,两种酶活性均下降(P < 0.05);而无氧运动对异柠檬酸脱氢酶和琥珀酸脱氢酶活性无影响。结果提示：长期的有氧运动和短时间的有氧无氧交替运动有利于提升骨骼肌异柠檬酸脱氢酶和琥珀酸脱氢酶的活性。     

异柠檬酸脱氢酶1对肝内胆管细胞癌中炎性反应的影响

目的研究肝内胆管细胞癌(ICC)中异柠檬酸脱氢酶1(IDH1) 132位点核苷酸突变与炎性反应的关系,探讨IDH1突变对ICC发生的影响。方法收集ICCs标本131例。采用Sanger法分析IDH1突变位点; HE观察ICC炎性反应发生情况。用Cre-LoxP系统,构建IDH1 R132H肠道组织特异性基因突变小鼠;分离小鼠肝脏内胆管,HE观察小鼠肝内胆管及胆道炎性反应情况。用突变型IDH1代谢产物2-羟基戊二酸(2-HG)对巨噬细胞系THP-1进行干预;收集培养液上清,ELISA检测上清中M1型巨噬细胞标志物肿瘤坏死因子(TNF-α)和M2型标志物白介素-10(IL-10)的浓度。结果 131例ICC标本中IDH1(R132H)突变率为15. 3%(20/131)。与IDH1野生型组相比,IDH1(R132H)突变组标本中炎细胞浸润明显增多(P0. 01);在肠道组织特异性突变小鼠模型中也得到一致结果(P0. 05)。2-HG能够诱导M2型巨噬细胞标志物IL-10表达增多(P0. 01),而M1型标志物TNF-α变化没有统计学意义。结论 IDH1突变能够诱发胆管发生炎性反应,并促进THP-1巨噬细胞系向M2型极化,为进一步明确IDH1突变与肝内胆管细胞癌发生的关系以及靶向治疗提供依据。     

结核分枝杆菌异柠檬酸裂解酶基因的克隆表达及鉴定

最近,Okada M等人报道,全世界每年因结核病死亡人数超过200万,新发病例超过880万。据WHO统计,全球80%的肺结核病例发生在中国、菲律宾等22个西太平洋国家。中国是世界第二大结核     

ACAD8基因新突变导致异丁酰辅酶A脱氢酶缺乏症的遗传学分析

目的 对一个新生儿代谢筛查异常患儿进行遗传学病因分析和遗传咨询。方法 采集患儿及父母外周血,经DNA提取后进行先证者单人全外显子组测序,根据ACMG指南筛选出致病性位点并通过Sanger测序验证父母来源。结果 全外结果发现患儿携带ACAD8基因c.302C>T(p.S101L)和c.712del(p.W238Gfs*9),均为杂合变异,父母分别为杂合变异携带者。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南进行变异致病性评级,这两个变异均为疑似致病性变异,其致病性均为首次报道。基因ACAD8突变会导致常染色体隐性遗传疾病异丁酰辅酶A脱氢酶缺乏症（IBDD）。该患儿无特异性临床表现,随访至20月龄生长发育正常,亦未见异常。结论 我们在IBDD患者中发现了ACAD8基因两个新突变c.302C>T(p.S101L)和c.712del(p.W238Gfs*9),丰富了人类ACAD8基因的致病性突变谱,从而有助于了解IBDD患者的遗传背景。同时为了进一步描述该遗传代谢病的临床表型,长期随访和监测是十分必要的。     

IDH1R132H在中枢神经系统胶质瘤中的表达及其鉴别诊断意义

目的 探讨异柠檬酸盐脱氢酶1基因(isocitrate dehydrogenase 1 gene,IDH1)突变的表达产物IDH1R132H在人中枢神经系统胶质瘤中的表达及其在鉴别诊断中的意义.方法 应用免疫组织化学EnVision法检测不同级别胶质瘤75例(包括WHOⅡ级33例,Ⅲ级20例和Ⅳ级22例)与各种原因造成的胶质增生性脑组织中IDH1R132H的表达情况,并与p53的表达情况进行比较分析.结果 IDH1R132H在WHOⅡ级、Ⅲ级和Ⅳ级胶质瘤的表达阳性率分别为57.6%(19/33)、40.0%(8/20)和27.3%(6/22),差异有统计学意义(P=0.024).IDH1R132H的具体表达部位在胶质瘤细胞的胞质、突起以及部分细胞核.除肿瘤主体部分密集增生的肿瘤细胞呈阳性表达以外,包括皮质和白质在内的肿瘤周边区域单个或散在的肿瘤细胞也呈强阳性表达.IDH1R132H阳性病例有额叶受累为主的倾向.胶质增生组织、毛细胞型星形细胞瘤均为阴性表达.另外,p53在WHOⅡ级、Ⅲ级和Ⅳ级胶质瘤的表达阳性率分别为42.4%(14/33)、65.0%(13/20)和77.3%(17/22).IDH1R132H的表达与p53的表达之间没有明确的相关性(P=0.766).结论 IDH1R132H在各级别胶质瘤中均有表达,且随着肿瘤级别的增高呈表达下降趋势.IDH1R132H可以作为鉴别低级别胶质瘤和胶质增生性病变的一个有用的分子标志物.

Abstract：

Objective To investigate the immunohistochemical expression of isocitrate dehydrogenase 1 gene ( IDH1 ) R132H in glioma and its diagnostic utility. Methods Immunohistochemical study of IDH1R132H expression was performed on formalin-fixed paraffin-embedded tissue samples of 75 gliomas, including 33 cases of grade Ⅱ , 20 cases of grade Ⅲ and 22 cases of grade Ⅳ tumors. Six cases of pilocytic astrocytoma and 12 cases of gliosis were used as controls. Results Nineteen in 33 cases of grade Ⅱ (57.6%), 8 in 20 cases of grade Ⅲ (40. 0% ), 6 in 22 cases of grade Ⅳ (27. 3% ) showed positive cytoplasmic staining of IDH1R132H. Scattered invasive glioma cells at the tumor periphery also expressed IDH1R132H. Gliomas involving the frontal lobe showed more strong IDH1R132H staining. In contrast, none of the pilocytic astrocytomas and gliosis showed IDH1R132H staining. Moreover, the rate of p53 immunopositivities were 42. 4% ( 14/33 ) in grade Ⅱ , 65.0% (13/20) in grade Ⅲ and 77.3% (17/22) in grade Ⅳ gliomas. There were no statistic correlations between expression of IDH1R132H and p53.Conclusion IDH1R132H tends to express preferentially in low-grade gliomas, and it thus may serve as a valuable marker in distinguishing low grade gliomas from gliosis.     

Isocitrate dehydrogenase 1 and 2 mutations in cholangiocarcinoma

Somatic mutations in isocitrate dehydrogenase 1 and 2 genes are common in gliomas and help stratify patients with brain cancer into histologic and molecular subtypes. However, these mutations are considered rare in other solid tumors. The aims of this study were to determine the frequency of isocitrate dehydrogenase 1 and 2 mutations in cholangiocarcinoma and to assess histopathologic differences between specimens with and without an isocitrate dehydrogenase mutation. We sequenced 94 formalin-fixed, paraffin-embedded cholangiocarcinoma (67 intrahepatic and 27 extrahepatic) assessing for isocitrate dehydrogenase 1 (codon 132) and isocitrate dehydrogenase 2 (codons 140 and 172) mutations. Multiple histopathologic characteristics were also evaluated and compared with isocitrate dehydrogenase 1/2 mutation status. Of the 94 evaluated specimens, 21 (22%) had a mutation including 14 isocitrate dehydrogenase 1 and 7 isocitrate dehydrogenase 2 mutations. Isocitrate dehydrogenase mutations were more frequently observed in intrahepatic cholangiocarcinoma than in extrahepatic cholangiocarcinoma (28% versus 7%, respectively; P = .030). The 14 isocitrate dehydrogenase 1 mutations were R132C (n = 9), R132S (n = 2), R132G (n = 2), and R132L (n = 1). The 7 isocitrate dehydrogenase 2 mutations were R172K (n = 5), R172M (n = 1), and R172G (n = 1). Isocitrate dehydrogenase mutations were more frequently observed in tumors with clear cell change (P < .001) and poorly differentiated histology (P = .012). The results of this study show for the first time that isocitrate dehydrogenase 1 and 2 genes are mutated in cholangiocarcinoma. The results of this study are encouraging because it identifies a new potential target for genotype-directed therapeutic trials and may represent a potential biomarker for earlier detection of cholangiocarcinoma in a subset of cases.     

A population-based study of high-grade gliomas and mutated isocitrate dehydrogenase 1

High-grade gliomas have a dismal prognosis, and prognostic factors are needed to optimize treatment algorithms. In this study we identified clinical prognostic factors as well as the prognostic value of isocitrate dehydrogenase 1 (IDH1) status in a population-based group of patients with high-grade gliomas. Using the Danish Cancer Registry and the Danish Pathology Databank we identified 359 patients: 234 had WHO grade IV gliomas, 58 had WHO grade III gliomas, and 67 were diagnosed clinically. Mutated IDH1 was predominantly observed in oligodendroglial tumors (WHO grade III). Patients with mutated IDH1 had a significantly better outcome than patients with wildtype IDH1: 2-year OS 59% and 18%, respectively (HR 0.38, 95% CI 0.21-0.68). However, when adjusting for other prognostic factors, IDH1 status was not a significant independent prognostic factor (HR=0.58, 95% CI 0.32-1.07). Young age, absence of neurological deficit, performance status 0–1, tumor not crossing the midline, and receiving post-surgical treatment were significant independent indicators of a good prognosis in multivariate analysis. In conclusion: This population-based study could not demonstrate IDH1 status to be an independent prognostic factor in high-grade gliomas when adjusting for the effect of classic prognostic factors.     

Oxidative status and distribution of NADP-dependent isocitrate dehydrogenase and aconitate hydratase in rat cardiomyocytes under normal conditions and during ischemia

Oxidative status of rat cardiomyocytes during ischemia induced by occlusion of the descending branch of the coronary artery was studied by the methods of Fe-induced chemiluminescence and spectrophotometry of primary and secondary lipid peroxidation product. The concentrations of low-molecular-weight antioxidants a-tocopherol and citrate and activities of NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41) and aconitate hydratase (EC 4.2.1.3) were also measured. Ischemia was associated with intensification of free radical processes, increased antioxidant activity in subcellular fractions of the myocardium, activation of NADP-isocitrate dehydrogenase, accumulation of citrate, and inhibition of aconitate hydratase. Differential centrifugation, ion exchange chromatography on various ion exchangers, and electrophoresis in polyacrylamide gel revealed no redistribution of enzyme activity between the cytoplasmic and mitochondrial cardiomyocyte fractions during ischemia.     

Induction of sarcomas by mutant IDH2

More than 50% of patients with chondrosarcomas exhibit gain-of-function mutations in either isocitrate dehydrogenase 1 (IDH1) or IDH2. In this study, we performed genome-wide CpG methylation sequencing of chondrosarcoma biopsies and found that IDH mutations were associated with DNA hypermethylation at CpG islands but not other genomic regions. Regions of CpG island hypermethylation were enriched for genes implicated in stem cell maintenance/differentiation and lineage specification. In murine 10T1/2 mesenchymal progenitor cells, expression of mutant IDH2 led to DNA hypermethylation and an impairment in differentiation that could be reversed by treatment with DNA-hypomethylating agents. Introduction of mutant IDH2 also induced loss of contact inhibition and generated undifferentiated sarcomas in vivo. The oncogenic potential of mutant IDH2 correlated with the ability to produce 2-hydroxyglutarate. Together, these data demonstrate that neomorphic IDH2 mutations can be oncogenic in mesenchymal cells.     

NADP+-dependent isocitrate dehydrogenase isozymes from a psychrotrophic bacterium,Psychrobacter sp. strain 13A

The genes encoding dimeric and monomeric isocitrate dehydrogenase (IDH) isozymes from a psychrotrophic bacterium, strain 13A (13AIDH-D and 13AIDH-M, respectively), were cloned and sequenced. The deduced amino acid sequences of these two IDHs showed high degrees of identity with those of bacteria of genus Psychrobacter. Analysis of the 16S ribosomal RNA gene of the strain 13A revealed that this bacterium is classified to genus Psychrobacter. The optimum temperatures for activities of 13AIDH-D and 13AIDH-M were 55°C and 45°C, respectively, indicating that they are mesophilic. On the contrary, 13AIDH-D maintained 90% of its maximum activity after incubation for 10 min at 50°C, while the 13AIDH-M activity was completely lost under the same condition. In addition, 13AIDH-D showed much higher specific activity than 13AIDH-M. From northern and western blot analyses, the 13AIDH-D gene was found to be not transcribed under the growth conditions tested in this study. However, the catalytic ability of the mesophilic 13AIDH-M was concluded to be enough to sustain the growth of strain 13A at low temperatures. Therefore, a novel pattern of the contribution of IDH isozymes in cold-living bacteria to their growth at low temperatures was confirmed in strain 13A.     

胆管癌的分子生物学进展

胆管癌早期诊断困难,预后差。越来越多的研究证据表明：多基因、多步骤的遗传性改变,包括癌基因(如bcl-2,c-erbB-2,k-ras)激活、抑癌基因(如p53,DPC4/Smad4,nm23)失活等可能是胆管癌发生的分子基础, 胆管癌在其发生发展过程中可使多种肿瘤标志物升高,如MUC,Cal9-9等。