Differential expression of genes during aflatoxin B(1)-induced hepatocarcinogenesis in tree shrews

AIM:Through exploring the regulation of gene expression during hepatocarcinogenesis induced by aflatoxin B1 (AFB1),to find out the responsible genes for hepatocellular carcinoma (HCC) and to further understand the underlying molecular mechanism.METHODS:Tree shrews ( Tupaia belangeri chinensis)were treated with or without AFB1 for about 90 weeks. Liver biopsies were performed regularly during the animal experiment. Eight shares of total RNA were respectively isolated from 2 HCC tissues, 2 HCC-surrounding noncancerous liver tissues, 2 biopsied tissues at the early stage(30^th week) of the experiment from the same animals as above, 1 mixed sample of three liver tissues biopsied at the beginning (0^th week) of the experiment, and another i mixed sample of two liver tissues from the untreated control animals biopsied at the 90^th week of the experiment. The samples were then tested with the method of Atlas^TM cDNA microarray assay. The levels of gene expression in these tissues taken at different time points during hepatocarcinogenesis were compared.RESULTS:The profiles of differently expressed genes were quite different in different ways of comparison.At the same period of hepatocarcinogenesis, the genes in the same function group usually had the same tendency for up-or down-regulation. Among the checked 588 genes that were known to be related to human cancer, 89 genes (15.1%) were recognized as “important genes” because they showed frequent changes in different ways of comparison. The differentially expressed genes during hepatocarcinogenesis could be classified into four categories: genes up-regulated in HCC tissue, genes with similar expressing levels in both HCC and HCC-surrounding liver tissues which were higher than that in the tissues prior to the development of HCC,genes down-regulated in HCC tissue, and genes up-regulated prior to the development of HCC but down-regulated after the development of HCC.CONCLUSION: A considerable number of genes could change their expressing levels both in HCC and in HCC-surrounding non-cancerous liver tissues. A few modular genes were up-regulated only in HCC but not in surrounding liver tissues, while some apoptosis-related genes were down-regulated in HCC and up-regulated in surrounding liver tissues. To compare gene-expressing levels among the liver tissues taken at different time points during hepatocarcinogenesis may be helpful to locate the responsible gene (s) and understand the mechanism for AFB1 induced liver cancer.     

用cDNA阵列技术研究黄曲霉毒素B1诱发树鼩肝癌形成过程中的基因变化

目的 对树鼩肝癌形成过程中的基因表达差异进行动态分析,探讨肝癌发生的分子机制。 方法用cDNA阵列技术,将2例黄曲霉毒素B1诱发的树鼩肝癌组织分别与其癌旁组织和其肝癌形成前的活检肝组织、实验前对照和同期对照肝组织进行基因表达水平的6种比较分析。结果 不同的比较方式所显示的差异表达的基因谱不同,可归为4类:癌组织表达高于癌旁组织、癌旁组织表达高于癌发生前肝的组织;癌与癌旁表达水平相仿,但高于癌发生前的肝组织;癌组织下调,低于癌旁组织;癌发生前表达上调,在癌发生后表达下调。 结论 对肝癌形成过程中不同时期的肝组织基因表达水平进行动态对比分析,有助于阐明肝癌发生的分子机制并最终筛选出与肝癌发生有关的关键基因。     

Proliferative drive and liver carcinogenesis: Too much of a good thing?

There have been innumerable studies published in the attempt to identify gene expression signatures in hepatocellular carcinoma (HCC). When all the regulators and targets of the differentially expressed genes are analyzed from larger studies, the most striking theme is upregulation of mitosis‐promoting and cell proliferation genes in HCC compared with ‘liver‐specific gene clusters’ in non‐tumorous tissue. A major limitation of expression profiling is that it only provides a ‘snapshot’ of what is an evolving process and thus cannot distinguish the differences in gene expression that are primary effectors of dysregulated growth from those that represent downstream consequences. The development of HCC in a chronically diseased liver, often referred to as hepatocarcinogenesis, is a multistep process characterized by the progressive accumulation and interplay of genetic alterations causing aberrant growth, malignant transformation of liver parenchymal cells, followed by vascular invasion and metastasis. This review will discuss HCC precursor lesions, draw on the ‘proliferation cluster’ genes highlighted from HCC expression profiling studies, relate them to a selection of regulatory networks important in liver regeneration, cell cycle control and their potential significance in the pathogenesis of HCC or primary liver cancer.     

二乙基亚硝胺诱发大鼠肝癌过程中癌前病变阶段差异表达蛋白质的筛选

目的 通过比较二乙基亚硝胺(DEN)诱发大鼠肝细胞癌发生过程中不同阶段的蛋白质表达谱,筛选在大鼠肝癌前病变阶段起重要作用的蛋白质分子. 方法大鼠分为DEN组和正常对照组,诱癌过程中定期处死动物并取其肝组织;以γ-谷氨酰转肽酶染色阳性的肝细胞增生灶为标志,识别和获取肝癌前病变的组织标本.用双向电泳及基质辅助激光解吸飞行时间串联质谱法对大鼠正常肝组织、癌前病变组织和肝癌组织的全蛋白质组表达谱进行比较和鉴定.用Western blot和RT-PCR方法对部分差异表达蛋白质(如层黏连蛋白受体1和鲱精胺酶)进行表达水平的验证.结果 筛选出表达水平差异≥2倍的蛋白质共82种,其中在癌前病变阶段即发生明显改变的差异表达蛋白质有47种,包括在正常对照组、癌前病变组、肝癌组呈现依次上调的层黏连蛋白受体1等8种蛋白质和在上述组织中呈现依次下调的鲱精胺酶等22种蛋白质.Western blot和RT-PCR方法对层黏连蛋白受体1和鲱精胺酶表达水平的验证结果与双向电泳的结果相似.结论 大鼠肝癌形成过程中不同阶段的蛋白质表达谱有所不同,对癌前病变的差异表达蛋白质如层黏连蛋白受体1和鲱精胺酶等进行深入探讨,有望为人类肝癌的早期诊断和治疗提供线索.     

Expression of the transcription factor Klf6 in cirrhosis, macronodules, and hepatocellular carcinoma

Background and Aims: Macronodules (MN) occurring in cirrhosis are considered to be precursor lesions for hepatocellular carcinoma (HCC). However, early molecular events in hepatocellular carcinogenesis are poorly understood. The aim of this study was to compare gene expression profiling between cirrhotic tissues, MN, and HCC, to identify genes early involved in liver carcinogenesis. Methods: Tissues were obtained from explanted livers: nine cirrhosis, 10 MN, and seven HCC. Total RNAs were extracted by RNeasy and reverse transcribed with labelled [³³P]‐αATP. Hybridations were performed on Atlas Human Cancer 1.2 membranes (1176 genes). Results: A two‐way hierarchical clustering algorithm successfully isolated specific gene expression profiles when comparing MN, cirrhosis, and HCC. A total of 16 and 14 genes were up‐ and down‐expressed, respectively, in HCC as compared to cirrhotic tissues. The molecular signature of MN was characterized by the down‐expression of 23 and 42 genes as compared to cirrhosis and HCC, respectively. Among them, Klf6 was down‐expressed in all MN samples whereas it was over‐expressed in cirrhosis and HCC. This result was confirmed at RNA level by quantitative real time–polymerase chain reaction and at protein level by Western blotting. However, no mutation in the exon 2 of Klf6 was detected. Conclusion: We identified a molecular signature of MN characterized by a down‐expression of several genes. One of them, Klf6 was found to be down‐expressed in all MN without evidence of somatic mutations in the exon 2. This gene could be involved at an early stage of hepatocarcinogenesis.     

Expression of p53and C—myc genes and its clinical relevance in the hepatocellular carcinomatous and pericarcinomatous tissues

AIM：To investigate the possible roles of p53and C-myc genes in the primary hepatocellular carciogenesis and the relationship between the liver hyperplastic nodule(LHN)and hepatocellular carcinoma(HCC).METHODS:The expression of p53and C-myc genes was detcted immunohist-ochemically in 73and 60cases of HCCand pericarcinomatous tissues,respectively.RESULTS:The positive expression of p53in HCCwas significantly higher than that in pericarcinomatous tissues(P<0.050.In pericarcinomatous tissues,the p53 expression was observed onlyin LHN,but not in liver cirrhosis(LC)and normal liver tissues.The positive expression rate of C-myc in HCC or LHN was significantly higher than that in LCor normal liver tissues(P<0.05and P<0.01).however,no significant difference was found between HCCand LHN(P>0.05).The positive expression rate of p53and C-myc in HCCwas correlated with the histological differentiation,that in the poorly6 differentiated was significantly higher than that in well differentiated samples(P<0.05).CONCLUSION:The overexpression of p53and C-myc genes might play a orle in the carcinogenesis of HCC;And LHN seems a preneoplastic lesion related to hepatocarcinogenesis.No evidence supports that LC contribute directly to the hepatocarcinogenesis.     

应用基因芯片技术筛选肝细胞癌相关基因

目的:探讨基因表达谱芯片技术在筛查肝细胞癌(HCC)相关基因群表达中的作用。方法:TRIzol法抽提2例HCC及正常肝脏组织总RNA,分离纯化两种组织的mRNA;逆转录合成掺入生物素标记的cDNA合成探针,与基因芯片(涵盖了18400个转录本,代表了14 500个明晰的基因)杂交,扫描芯片荧光信号图像,计算机分析,比较2种组织基因表达谱差异。结果:2例HCC组织与正常肝脏组织相比,有2756条基因(19.01%)共同表达差异,其中共同上调基因1772条和共同下调基因984条,对2756条共同差异表达基因作了初步功能分类,这些基因与HCC的发病机制存在相关性。结论:基因表达谱芯片技术可以筛选出HCC表达异常的相关基因群,有助于认识肝癌的发病机制。     

用树鼩cDNA芯片研究树鼩肝癌中参与信号传导的部分基因变化情况

目的利用树鼩cDNA芯片研究黄曲霉毒素B1（AFBl）和（或）乙型肝炎病毒（HBV）引起的树鼩肝细胞癌（HCC）发生过程中参与信号传导的部分基因表达变化情况，从而进一步探讨HCC发生的分子机制。方法实验树鼩分3组：A组（AFB1组）、B组（AFB1＋HBV组）、C组（正常对照组）。所有动物在实验过程中定期接受剖腹手术取肝组织检查，至肝癌形成时处死动物取肝癌和癌旁组织。用树鼩cDNA芯片检测实验第30、60、90周肝活检组织、肝癌组织及其癌旁组织中各基因的表达情况，并用实时逆转录聚合酶链反应（Real time RT-PCR）法验证cDNA芯片结果。结果在A组和B组从癌前到癌变过程中胰岛素样生长因子-Ⅱ（IGF-Ⅱ）、C-rel、核因子-κB2（NF—κB2）均显示有差异表达，同时bcl-2、细胞周期素A（cyclin A）、睫状神经营养因子（CNTF）仅在B组显示有差异表达。而C组这几个基因无差异表达。实验组与对照组比较，在诱癌的早、中期（30、60周）均出现CNTF及cyclin A的差异表达。realtime RT PCR结果与cDNA芯片检测结果基本一致。A组IGF-Ⅱ、C—rel基因及B组IGF-Ⅱ基因，在肝癌组织表达水平明显低于癌旁及实验30、60周组织，而癌旁与实验30、60周相比较则无明显差异；B组CNTF基因在癌旁、肝癌及60周之间比较无明显改变，但均明显高于30周；A组CNTF基因表达水平在癌旁、肝癌组织高于癌前组织，但差异无统计学意义；C组这3个基因不同时期比较亦无明显差异。结论树目自部分信号传导通路相关cDNA芯片应用于检测树目目HCC发生过程中信号传导通路中各基因表达的变化，对进一步了解树鼠甸HCC发生的机制有重要实用价值。IGF-Ⅱ、NF-κB2、C-rel、Bcl-2、cyclin A及CNTF这几个基因与树HCC的发生发展密切相关。     

Expression of microsomal prostaglandin E synthase-1 in human hepatocelluar carcinoma.

BACKGROUND/AIMS: The objective of this study was to evaluate the expression of microsomal prostaglandin E synthase-1 (mPGES-1) in hepatocellular carcinoma (HCC) tissues. METHODS: Forty surgically resected HCC tissues with adjacent non-tumorous liver tissues and 14 surgically resected, histologically normal liver tissues were used. The immunohistochemical expressions of the mPGES-1 protein in these HCC tissues and normal control livers were analysed. mPGES-1 mRNA expression was also analysed by the real-time polymerase chain reaction method using the same tissues. RESULTS: Microsomal prostaglandin E synthase-1 was not expressed in hepatocytes but instead in vascular endothelial cells and bile duct epithelial cells in normal liver tissues. The mPGES-1 expression in HCC tissues was significantly greater than its expression in the non-tumorous tissues. All types of HCC expressed more mPGES-1 than normal or hepatitis livers, and the levels of mPGES-1 expression in poorly differentiated HCC were similar to the levels in well-differentiated HCC. The mPGES-1 mRNA expression paralleled its protein expression in these tumorous and non-tumorous tissues. CONCLUSIONS: The present study is the first to demonstrate a high expression of mPGES-1 in well-differentiated HCC as well as in poorly differentiated HCC. These findings suggest that mPGES-1 may play a role in the advanced as well as early stage of hepatocarcinogenesis.     

Hepatic gene expression profiles associated with fibrosis progression and hepatocarcinogenesis in hepatitis C patients

AIM: To determine fibrosis progression and hepatocellular carcinoma (HCC), using simultaneous gene expression analysis. METHODS: Total RNA samples were extracted from liver biopsies from 19 patients with hepatitis C virus (HCV) infection and 3 patients without HCV infection. Among the 19 HCV-infected patients, 7 and 12 patients had grade Fl-2 and F3-4 fibrosis, respectively. Of the 12 patients with F3-4 fibrosis, 8 had HCC. Gene expression in the liver samples was determined using an oligonucleotide microarray. The following comparisons were performed: normal livers vs HCV-infected livers; F1-2 vs F3-4; and F3-4 with HCC vs F3-4 without HCC. Genes that were differentially expressed between these groups were identified based on signal-to-noise ratios. RESULTS: In the HCV-infected livers, genes involved in immune responses were highly expressed. Expression levels of genes for plasma proteins and drug-metabolizing enzymes were decreased and those of genes involved in the cell cycle and oncogenesis were increased in the F3-4 cases as compared to the F1-2 cases. Among the F3-4 cases, genes involved in carbohydrate metabolism tended to be more highly expressed in patients with HCC than in patients without HCC. CONCLUSION: We identified genes that are associated with fibrosis progression and hepatocarcinogenesis. This information may be used to detect increased carcinogenic potential in the livers of patients with HCV infection.     

基因芯片在肝细胞癌相关基因筛选中的初步研究

目的探讨基因表达谱芯片技术在筛查肝细胞癌相关基因群表达中的作用。方法采用美国Affymetrix公司的U133A2．0基因表达谱芯片，按一步法抽提肝细胞癌及正常肝脏组织总RNA，分离纯化两种组织的mRNA；经逆转录合成掺人生物素标记的cDNA合成探针，与芯片杂交和严格洗片后，用荧光扫描仪扫描芯片荧光信号图像，分析肝细胞癌及正常肝组织中差异表达的基因。结果在18400条基因中，肝细胞癌组织与正常肝脏组织间有2756条（14．98％）存在差异表达的基因，其中上调基因1772条和下调基因984条，对2756条差异表达基因作了初步功能分类，这些基因与肝细胞癌的发病机制存在相关性。结论基因表达谱芯片技术可以筛选出肝细胞癌表达异常的相关基因群，对其进一步研究有助于认识肝细胞癌的发病机制。     

应用基因芯片研究肝细胞癌组织差异基因表达谱

目的：应用基因芯片技术研究原发性肝细胞癌组织中的差异基因表达谱改变，以寻找肝细胞癌相关基因。方法：抽提正常肝组织和肝癌组织中的mRNA来制备探针，经杂交、洗涤后，通过计算机扫描分析正常肝组织和肝癌组织基因表达谱的差异情况。结果：在10000个候选基因中，筛选出102条差异表达基因，表达上调的有42条，表达下调的有60条。未知基因12条。结论：基于DNA微阵矩技术的肿瘤基因表达谱分析能够高通量筛选与肝癌发生发展相关的基因。     

多房棘球蚴病患者肝病灶组织差异表达基因的研究

目的探讨多房棘球蚴感染小鼠肝差异基因在多房棘球蚴病患者肝病灶组织中的表达情况及意义。方法选取高通量基因表达数据库中编号为GSE24376的小鼠感染多房棘球蚴基因芯片数据集,分析感染小鼠和未感染小鼠之间的差异表达基因,对差异表达基因进行基因本体(GO)分析。取6例多房棘球蚴病患者肝病灶组织和距离病灶组织2 cm的周围肝组织,采用荧光定量PCR检测2个高表达差异基因mRNA相对转录水平。取45份多房棘球蚴病患者石蜡包埋肝组织样品(炎性反应和肝纤维化改变严重的病灶29份,较少炎性细胞浸润和肝纤维化病变的肝组织16份),采用免疫组化法分析2个高表达差异基因的表达情况。用SPSS 21.0统计学软件对数据进行统计分析。结果生物信息学分析结果显示,共筛选出21个差异表达基因,其中9个基因表达上调,12个基因表达下调。GO分析结果显示,差异基因主要位于细胞内囊泡及细胞外基质等细胞成分中,参与了中性粒细胞的脱颗粒及活化等生物过程,并且具有CC趋化因子受体结合活性及趋化因子活性。高表达差异基因CHI3L3 (在人体中为CHI3L1)和CCL8荧光定量PCR结果显示,6例多房棘球蚴病患者肝病灶组织中CHI3L1和CCL8 mRNA相对转录水平均高于病灶周围肝组织(P <0.01),最高倍数分别达7倍和9倍。免疫组化分析结果显示:29份多房棘球蚴病患者肝组织炎性反应和肝纤维化改变严重的病灶样品中,有20份(占69%)呈CHI3L1蛋白高表达,其主要着色部位位于细胞浆;有22份(占76%)呈CCL8蛋白高表达。16份多房棘球蚴病患者肝组织轻微炎症样品中,2份(占13%)呈CHI3L1蛋白阳性;4份(占33%)呈CCL8蛋白阳性。炎性反应和肝纤维化改变严重的病灶组织中,CHI3L1和CCL8蛋白的阳性表达率分别达96%和97%,均高于轻微炎症肝组织的3%和8%(P <0.01)。结论 CHI3L1和CCL8蛋白在多房棘球蚴病患者肝组织中表达增高,提示二者在机体对虫体的免疫应答过程中发挥了一定作用。