肝细胞癌组织Smad4基因表达及其临床意义的研究

目的:拟通过检测Smad4基因在肝细胞癌(HCC)中的表达,初步探讨TGFβ-Smad信号通路中Co-Smad(Smad4)与肝细胞癌的发生和发展之间的可能关系.方法:采用免疫组化ABC法及原位杂交法(ISH)检测41例肝细胞癌组织切片中癌与癌旁Smad 4蛋白和mRNA的表达,5例外伤性肝破裂手术切除标本作为正常对照.比较HCC组与对照组及HCC与癌旁Smad 4蛋白和mRNA表达的差异,并进行统计分析.结果:正常对照组Smad 4蛋白和mRNA均呈阳性表达;HCC组织Smad4蛋白阳性率为48.8%(20/41),癌旁组织中为78.0%(32/41),两者比较差异有统计学意义,P<0.01;HCC组织Smad4 mRNA阳性卒为51.2%(21/41),癌旁组织中为73.1%(30/41),两者比较差异有统计学意义,P<0.05;与正常肝组织比较,HCC组织中Smad4蛋白和mRNA阳性表达均显著降低,P<0.05;HCC组织Smad4 mRNA阳性表达在病理分级Ⅰ、Ⅱ级与Ⅲ、Ⅳ级之间差异有统计学意义,P<0.05.结论:Smad 4基因表达缺失可能在肝细胞癌的发生和发展中发挥作用.     

Smad4 expression in hepatocellular carcinoma differs by hepatitis status

Aims: Primary hepatocellular carcinoma (HCC) is a common malignancy often related to hepatitis viralinfection. Smad4 is known to mediate the TGF-β pathway to suppress tumorigenesis. However, the function ofSmad4 in HCC is still controversial. In this study we compared levels of Smad4 in HCC tissues with or withouthepatitis virus infection and adjacent normal-appearing liver. Methods: Samples from HCC patients wereanalyzed for Smad4 protein and mRNA expression by immunohistochemistry (IHC), RT-PCR and Westernblotting. Results: We found that tumor tissues expressed less Smad4 mRNA and protein than the adjacent tissues.Most HCC tumor tissues were negative for Smad4 in IHC staining, while the majority of adjacent tissues werepositively stained. Interestingly, protein levels were higher in HCC tissues with viral hepatitis than those withoutvirus infection. Suppression of expression appeared closely related to HCC, so that Smad4 appears to functionas a tumor suppressor gene (TSG). Conclusion: Patients with hepatitis viral infection, at higher risk for HCC,exhibited increased Smad4 protein expression suggesting hepatitis virus may modulate Smad4 expression, whichis functionally distinct from its putative role as a TSG. Smad4 expression may thus be an applicable marker fordiagnosis and/or a target to develop therapeutic agents for HCC.     

Novel mutations in transthyretin gene associated with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the major health problems with increasing incidence worldwide. We report the elevation in transthyretin (TTR) expression following HCC induction using diethylnitrosamine (DEN) and 2‐aminoacetylfluorine (2‐AAF) in male Wistar rats. The increase in its expression took place at very early stage and remained elevated throughout HCC progression. The analysis of TTR gene in HCC bearing rats revealed four novel mutations that alter three amino acids at positions 61, 100, and 115. While these mutations do not directly affect the binding of TTR to thyroxine (T₄), the mutation in amino acid 115 interferes with TTR tetramer formation that leads to its accumulation. Further, the mutated TTR is unable to cleave C‐terminal of apolipoprotein A1 (APOA1) that results in abnormal lipid metabolism. This has correlation with development of liver cirrhosis and HCC. Furthermore, the mutated TTR seems to have potential as biomarker for early detection of HCC.     

NOD2基因与原发性肝癌

核苷酸结合寡聚化结构域蛋白2（NOD2）可通过识别细菌细胞壁的肽聚糖及其裂解产物胞壁酰二肽,参与宿主对病原体的免疫应答,参与调节自然免疫和特异性免疫。NOD2作为一种新发现的细胞内模式识别受体,可通过基因变异、诱发肝脏炎症反应、激活相应信号通路在原发性肝癌的发生发展中发挥重要作用。     

No mutations of the Smad2 gene in human sporadic gastric carcinomas

BACKGROUND: The majority of cancer cells escape from TGF-beta-mediated growth control. However, the mechanism of resistance to the growth inhibitory effects by TGF-beta is not clear. TGF-beta signaling is initiated when the type I receptor phosphorylates the SMAD proteins, Smad2 and Smad3. Recently, mutations of Smad2 have been detected in human colon and lung cancers. Mutation of coding sequences of Smad2 in gastric carcinomas has not yet been elucidated adequately. METHODS: PCR-SSCP analysis of the entire coding region of Smad2 in 35 human sporadic gastric cancers and eight gastric cancer cell lines was performed using 11 sets of intron-based primers. RESULTS: No mutations of Smad2 were detected in any tumor or cell line. CONCLUSIONS: The results suggest that mutation of Smad2 does not play a key role in human stomach carcinogenesis.     

P53 tumor suppressor gene mutations in hepatocellular carcinoma patients in India

BACKGROUND: Specific mutations of the p53 tumor suppressor gene in hepatocellular carcinoma (HCC) have been reported from several parts of the world, but to the authors' knowledge to date the status of this gene has not been studied in HCC patients in India, where HCC is one of the major cancers and the frequency of chronic hepatitis B virus (HBV) as well as hepatitis C virus (HCV) infection and exposure to dietary aflatoxin B(1) is very high. The most frequent mutation of the p53 gene in HCC is an AGG(Arg) to AGT(Ser) missense mutation at codon 249 of exon 7. METHODS: Liver biopsy specimens from 21 HCC patients and 10 healthy controls were obtained through surgery or by needle biopsy technique. Phenol-chloroform-extracted DNA specimens were employed for the detection of HBV infection and p53 gene mutations. Nucleotide mutations of exons 4-9 of the p53 gene were analyzed by polymerase chain reaction (PCR), single strand confirmation polymorphism, and direct sequencing. Third-generation sandwich enzyme-linked immunosorbent assay (ELISA) was used for the serologic detection of HBV and HCV infection. RESULTS: Analysis of exons 4-9 of the p53 gene revealed only 3 mutations (3 of 21 specimens, 14.28%; 95% confidence interval, -0.7-29.3), 2 mutations at codon 249 showing G-->T transversions, and 1 mutation (4.7%) at codon 250 with a C-->T transition. The base substitutions at the third base of codon 249 resulted in a missense mutation leading to a change in amino acid from arginine to serine whereas at codon 250 it caused a change from proline to serine. Dot blot hybridization and PCR for HBV DNA from HCCs revealed 58.8% (10 of 17 specimens) and 90. 47% (19 of 21 specimens), positivity, respectively. ELISA for hepatitis B virus surface antigen in serum showed a positivity of 71. 42% (15 of 21 specimens), but there was only 40% positivity (8 of 20 specimens) for hepatitis B virus envelope antigen whereas 6 of 17 patients (35.29%) showed the presence of antibodies against hepatitis B virus envelope protein. No patient was found to be positive for the HCV antibody. CONCLUSIONS: The very low frequency of p53 mutations and the extremely high frequency of HBV infection (> 90%) in HCC indicate that the mutations in the p53 gene frequently found in HCC reported from different endemic areas of the world may not play a direct role in the development of HCC in India. HBV infection and, possibly, exposure to the dietary aflatoxin B(1) appear to play major roles in the molecular pathogenesis of HCC in India.     

肝细胞肝癌中T细胞转录因子4基因表达及突变

目的 :研究人T细胞转录因子 4(hTcf 4 )基因在肝细胞肝癌中表达及突变和肝癌发生发展的关系。方法 :用逆转录 -聚合酶链反应 (RT PCR)检测了 32例肝癌组织及癌旁组织中hTcf 4基因表达 ,并用聚合酶链反应 -单链构像多态性分析 (PCR SSCP)方法检测了肝癌组织中hTcf 4外显子 1、4、9、15的突变情况。结果 :hTcf 4mRNA在癌组织及癌旁组织中表达率分别为 90 .6 %和 71.9%。且癌组织中表达水平明显高于癌旁组织 [(0 .71±0 .13)vs (0 .2 9± 0 .0 5 ) ,P <0 .0 0 1]。同时 ,此基因在包膜不完整及有转移的癌组织表达增高更为显著。 32例肝癌中仅检测到 2例hTcf 4基因外显子 15突变 ,突变率为 6 .2 5 %。结论 :hTcf 4基因在肝细胞肝癌 ,尤其伴转移肝癌组织中表达增高 ,并与肝癌侵袭转移有关 ,而该基因突变与肝癌关系不密切。     

去唾液酸糖蛋白受体 2 基因在肝细胞性肝癌中的表达及意义

目的检测去唾液酸糖蛋白受体2（asialoglycoprotein receptor 2,ASGR2）基因在肝细胞性肝癌（hepatocellular carcinoma,HCC）中的表达水平,探讨ASGR2在HCC发生、发展中的作用和意义。方法以RT-PCR法检测55例HCC患者、55例非肝癌的其他肿瘤患者和33例非肿瘤的其他疾病对照患者外周血液中ASGR2基因的表达水平,并分析其意义。结果肝癌组和非肝癌的其他肿瘤组患者血液中ASGR2基因阳性表达率分别为85．5％、65．5％,两组差异有统计学意义（P〈0．05）,肝癌组和非肿瘤的其他疾病对照组ASGR2基因阳性表达率分别为85．5％、78．8％,两组差异无统计学意义（P〉0．05）,ASGR2基因在3组患者外周血液中的表达水平有明显差异（P〈0．05）。ASGR2基因的表达与HCC患者的性别、年龄、AFP、肝硬化、肿瘤家族史等临床病理特征均无统计学意义（P〉0．05）。结论ASGR2基因的表达水平可能与HCC发生、发展有关,检测ASGR2的水平有望作为HCC早期发病的预测指标。     

Smad4 deficiency in cervical carcinoma cells

Squamous cell carcinoma of the uterine cervix is one of the most frequent cancers affecting women worldwide. Carcinomas arise from cervical intraepithelial lesions, in which infection with high-risk human papillomavirus types has led to deregulated growth control through the actions of the viral E6 and E7 oncoproteins. The molecular mechanisms underlying progression to invasive tumor growth are poorly understood. One important feature, however, is the escape from growth inhibition by transforming growth factor beta (TGF-beta). Loss of chromosomal arm 18q is among the most frequent cytogenetic alterations in cervical cancers and has been associated with poor prognosis. Since the TGF-beta response is mediated by Smad proteins and the tumor suppressor gene Smad4 resides at 18q21, we have analysed the Smad4 gene for cervical cancer-associated alterations in cell lines and primary carcinomas. Here, we report Smad4 deficiency in four out of 13 cervical cancer cell lines which is due to an intronic rearrangement or deletions of 3' exons. All cell lines, however, showed either absent or moderate responsiveness to TGF-beta irrespective of their Smad4 status. In 41 primary squamous cervical carcinomas analysed, 10 samples showed loss of Smad4 protein expression and 26 samples a reduced expression. Altogether, our results strongly suggest that Smad4 gene alterations are involved in cervical carcinogenesis.     

PIN1 overexpression and beta-catenin gene mutations are distinct oncogenic events in human hepatocellular carcinoma

The peptidyl-proplyl-isomerase, PIN1, upregulates beta-catenin by inhibiting its interaction with APC. beta-catenin accumulation occurs in about 70% of hepatocellular carcinoma (HCC), of which only 20% are due to beta-catenin mutations. The role of PIN1 in beta-catenin upregulation in HCC was investigated. PIN1 was shown to be overexpressed in more than 50% of HCC. All cases with PIN1 overexpression also showed beta-catenin accumulation, with 68% of cases showing concomitant beta-catenin and cyclin D1 accumulation. PIN1 was shown to contribute to beta-catenin and cyclin D1 overexpression directly by in vitro cell-line transfection experiments. Finally, we showed that PIN1 overexpression and beta-catenin gene mutations appeared to be mutually exclusive events, leading to beta-catenin accumulation in HCC. These results showed that PIN1 overexpression leading to beta-catenin accumulation might be a critical event in hepatocarcinogenesis, and that PIN1 is a potential target for therapeutic intervention in HCC.     

肝癌患者β-catenin基因第三外显子的体细胞突变

目的探讨中国地区人肝癌发生发展过程中有无β-catenin基因突变.方法采用PCR-SSCP方法,设计扩增β-catenin基因第三外显子的引物,检测20例肝癌患者及7株人肝癌细胞中有无β-catenin基因突变,并通过DNA测序及限制性内切酶对突变加以验证.结果20例肝癌患者中有2例发生β-catenin基因突变,均为41位密码子由编码苏氨酸变成编码丙氨酸.7株人肝癌细胞均无β-catenin基因突变.结论10%(2/20)的肝癌组织样品有β-catenin基因突变.提示β-catenin基因突变可能参与了部分肝癌癌变过程,但不是中国地区肝癌发生发展过程中的主要和关键原因.     

食管鳞状细胞癌中Smad4基因CpG岛甲基化状态分析

目的：探讨食管鳞状细胞癌（esophageal squamous cell carcinoma,ESCC）中Smad4（mothers against decapentaplegic homolog 4）基因启动子区及第一外显子区的CpG岛甲基化状态及其与Smad4蛋白、TGF-β1蛋白表达之间的相关性。方法：128例ESCC组织标本采集自河北医科大学第四医院2004-2008年的手术病例,每例患者均取癌旁正常黏膜组织作对照。分别应用甲基化特异性PCR（methylmion specific PCR,MSP）、RT-PCR和免疫组织化学法检测ESCC组织及相应癌旁组织中Smad4基因CpG岛的甲基化情况、Smad4 mRNA和Smad4蛋白表达情况,应用免疫组织化学法检测TGF-β1的蛋白表达情况。结果：ESCC组织中Smad4基因启动子区CpG岛甲基化率为5.5%（7/128）,第一外显子5′非翻译区CpG岛甲基化率为305%（39/128）;相应癌旁正常黏膜组织均未检测到这两个位点的甲基化（P<0.05）;ESCC组织中Smad4甲基化率显著高于癌旁正常组织（P<005）。ESCC组织中Smad4 mRNA及蛋白表达显著低于癌旁正常组织（P<0.05）,且与Smad4甲基化相关。TGF-β1蛋白在ESCC组织中的表达率（66.4%）显著高于相应癌旁正常组织（21.9%,P<0.01）,且随ESCC分期的增高和分化程度的降低而升高（P<0.05）。Smad4和TGF-β1蛋白在ESCC中的表达呈明显的负相关（P<0.01)。结论: Smad4基因CpG岛甲基化及TGF-β1的过表达可能是ESCC发生机制之一,其中Smad4基因第一外显子5′非翻译区CpG岛比启动子区CpG岛更易发生甲基化,从而导致Smad4基因沉默。     

Mitochondrial D-loop mutations as clonal markers in multicentric hepatocellular carcinoma and plasma.

PURPOSE: Hepatocellular carcinoma (HCC) is a highly malignant tumor prone to multicentric occurrence. Differentiation between a true relapse of HCC and a second primary tumor is of clinical importance. We sought to identify mitochondrial mutations in HCC and test their use as clonal markers in this disease. EXPERIMENTAL DESIGN: Primary HCC tissue samples were obtained from 19 patients and analyzed for mutations within the mitochondrial displacement loop (D-loop). The discovered mutations were used to determine tumor clonality and provided the basis for detection of tumor DNA in corresponding plasma samples. RESULTS: Thirteen of 19 HCC cases (68%) were identified as having D-loop mitochondrial DNA (mtDNA) mutations in at least one tumor. In 3 of these 13 cases, the same mutation was observed in multiple tumors, indicating monoclonal origin. Remarkably, in 8 of 13 mutated cases, we detected deletion/insertion mutations in the C-tract, a recently reported hotspot and potential replication start site of the closed, circular mitochondrial genome. In addition, we detected mutant mtDNA in 8 of 10 tested paired plasma DNA samples using a highly sensitivity molecular assay. CONCLUSIONS: mtDNA mutations within the D-loop control region are a frequent event in HCC, providing a molecular tool for the determination of clonality. In addition, detection of tumor-specific mtDNA mutations in plasma DNA needs to be explored further for monitoring patients with primary HCC.     

p53 gene mutation spectrum in hepatocellular carcinoma.

In order to clarify the significance of mutation of the p53 tumor suppressor gene in the genesis and development of human hepatocellular carcinoma (HCC) in an aflatoxin B1 low-exposure area, the spectrum, i.e., incidence, type, and site, of p53 gene mutations was examined in 169 tissue samples resected mainly from Japanese patients using single-strand conformation polymorphism analysis and direct sequencing. Forty-nine tumors (29%) showed a p53 mutation (39 point mutations and 10 frameshifts). The point mutations comprised 18 transitions, only 4 of which occurred at CpG sites, and 21 transversions. Two evolutionarily conserved domains, IV and V, contained 65% of all mutations and codon 249 was the most frequent mutation site (7/49). The spectrum of p53 mutation did not differ among HCCs in relation to the type of hepatitis virus infection, sex, age, and background liver disease of patients, tumor size, or presence of metastasis, but incidence and site were significantly associated with the degree of differentiation of cancer cells. In poorly differentiated HCC, p53 mutation was frequent (54%) and clustered on domains IV and V, whereas in well or moderately differentiated HCC, the mutation was less frequent (21%) and equally distributed on domains II to V. Restriction fragment length polymorphism analysis revealed loss of heterozygosity on chromosome 17p in 55 (69%) of 80 informative cases and in 34 (95%) of 36 cases with p53 mutation. Therefore, p53 gene mutation is suggested to occur independently of the type of viral infection or status of preexisting liver disease and to occur preferentially in moderately and poorly differentiated HCCs in association with or after loss of another p53 allele as a late event of HCC progression.     

p53 gene mutations in human endometrial carcinoma.

Although carcinoma of the uterine endometrium is the most frequently diagnosed malignancy of the female reproductive tract, the molecular genetic features of this tumor have yet to be described in significant detail. Since mutations of the p53 tumor suppressor gene are the single most common genetic alteration found in human malignancies, we examined the hypothesis that p53 mutations occur in human endometrial carcinoma. Sequencing analysis of exons 5-8 revealed point mutations in 3 of 21 (14%) tumors; one mutation was an unusual single-base insertion at codons 176-177, resulting in a premature stop codon, whereas the other two were CGG----TGG transitions at codon 248. Two of these tumors showed reduction to homozygosity at the p53 allele, but one tumor apparently retained heterozygosity. These data indicate that p53 mutations occur in human endometrial carcinoma, although relatively infrequently, and that loss of the normal p53 allele does not necessarily occur with point mutation of the p53 gene in this tumor type.     

Mutation analysis of transforming growth factor beta type II receptor, Smad2, Smad3 and Smad4 in esophageal squamous cell carcinoma

Mutations of the transforming growth factor beta type II receptor (TGFbetaRII) gene and Smad family genes have been observed in several human cancers. However, there has been no report on mutation analysis of the entire coding regions of these genes in esophageal cancer, and the role of these genes in the development of esophageal cancer remains unknown. We performed polymerase chain reaction-single strand conformation polymorphism analysis of TGFbetaRII, Smad2, Smad3 and Smad4 genes and microsatellite assay in 20 esophageal squamous cell carcinomas (ESCC). We detected polymorphisms at exon 2 of Smad3 and intron 6 of Smad4. No mutation was found in TGFbetaRII, Smad2, Smad3 and Smad4 genes. These results suggest that mutation of TGFbetaRII, Smad2, Smad3 and Smad4 genes is a rare event in ESCC.