启东肝癌高发区肝癌患者血清中p53突变研究

目的：研究启东地区肝癌患者血清中p53基因突变，并确定其对肝癌诊断的意义。方法：收集25例肝癌，20例肝硬化，30例健康对照者的血标本，提取DNA，应用限制性酶切及直接序列分析方法测定p53基因第七外显子突变。结果：显示p53基因第七外显子的249密码子产生突变，ARC变为SER，肝癌，肝硬化，健康者中发生率分别为44％（11／25），20％（4／20），7％（2／30）（P＜0．01），结论：启东地区肝癌患者血清中p53突变与肝癌发生密切相关，其可作为新的肝癌早期诊断标志。     

广西黄曲霉毒素高危区肝癌p53基因序列改变

目的　检测广西肝细胞癌 p53基因的序列改变。方法　 4 0例肝细胞性肝癌 ( HCC)分两组 :一组 2 6例 ,来自广西扶绥地区已知 HCC、黄曲霉毒素 ( AFB1)和乙型肝炎病毒 ( HBV)高危区 ;对照组 14例 ,来自广西玉林地区 ,该地 HCC和 HBV高危 ,但 AFB1可能低 ,因居民以低 AFB1的大米为主食。第七外显子直接测序。 p53蛋白和 HBs Ag免疫染色。结果　扶绥组 16/ 2 6例 ,占 61.5% ,2 4 9密码子第三号位 G→ T颠换 ,形成公认的突变热点。玉林组仅在贵港地区 p53突变集中在热点 ,为 3/ 5例 ,其他地区第七外显子突变点则分散在不同位点。全组 38/ 4 0例 HBs Ag( ) ,占 95%。结论　除启东和南部非洲外 ,世界上第三个 AFB1高危区肝癌 p53基因出现特异突变位点。已知肝癌 p53基因突变发生在这热点则提示该地 AFB1高污染。 HBV常伴随这些基因改变。     

肝癌非高发区安徽省肝细胞癌p53基249密码子点突变的研究

目的： 研究 p53基因 249密码子在肝癌非高发区安徽省的点突变的发生率。方法：应用 PCR- RFLP技术分析肝细胞癌 p53基因 249密码子突变的频率。结果：所检测的 38例肝细胞癌均无出现 p53基因第七外显子纯合性缺失, 4例有 p53基因 249密码子的点突变,且均为杂合型突变,突变率为 10.53％ (4/38)。结论：本资料说明,在肝细胞癌非高发区中 ,肝细胞癌中 p53基因第七外显子发生的点突变并非为高发事件。提示 p53基因第七外显子的点突变在肝癌非高发区肝细胞癌的形成过程中可能不起主导作用。     

广西原发性肝细胞癌黄曲霉毒素B1-DNA加合物表达及p53第249密码子突变分析

目的 通过研究广西地区肝癌患者中黄曲霉毒素B1(Aflatoxin B1,AFB1)-DNA加合物的表达和p53第249密码子突变情况及其关系,探讨AFB1长期暴露与人群原发性肝细胞癌(hepatocellular carcinoma,HCC)发生的关系.方法 实验组为广西医科大学第一附属医院肝胆外科收治的63例HCC患者行根治性手术切除的肝肿瘤组织.按肿瘤大小分为小肝癌组(≤5cm)和大肝癌组(＞5cm),同时小肝癌组包括两个亚组Ⅰ组(≤3cm)和Ⅱ组(＞3cm).另取10例来自肝移植供肝及肝外伤切除的正常肝组织作为正常对照组.通过免疫组织化学(immunohistochemistry,IHC)法检测各组样本AFB1-DNA加合物的表达,并以PCR结合直接测序的方法 检测其p53第249密码子的突变情况.结果 小肝癌组的AFB1-DNA加合物阳性率最高(73.8%),显著高于大肝癌组(P=0.016).而小肝癌组p53第249密码子的突变率(35.7%)却显著低于大肝癌组(P=0.007).正常对照组AFB1-DNA加合物阳性率为50.0%,但未发现p53第249密码子存在突变.Ⅰ组与Ⅱ组之间无论是AFB1-DNA加合物阳性率还是p53第249密码子的突变率差异均无统计学意义(P1=0.676,P2=1.000).实验组中,33.3%的样本为AFB1-DNA加合物和p53第249密码子突变双阳性,22.2%的样本为AFB1-DNA加合物和第249密码子突变双阴性.结论 广西为AFB1高污染地区,正常人群普遍存在AFB1的暴露.AFB1的暴露可增加HCC的发病概率.p53第249密码子突变可能是影响AFB1相关HCC发生、发展的因素.结合AFB1-DNA加合物表达和第249密码子突变的情况,可有效地了解肝癌患者长期持续性或非持续性的AFB1暴露下DNA的累积损伤情况.     

西南地区原发性肝癌抗癌基因P53点突变的研究

 本文采用PCR－RFLP技术对西南地区原发性肝细胞癌P⁵³基因第248和249位密码子点突变进行了研究。约17．4%的肝癌存在第249位密码子点突变。没有发现248位密码突变。本研究结果提示癌基因P⁵³点突变在该地区肝癌发病中起有一定作用；西南地区肝癌的发生可能有AFB1的参与。     

广西原发性肝细胞癌黄曲霉毒素B_1-DNA加合物表达及p53第249密码子突变分析

目的通过研究广西地区肝癌患者中黄曲霉毒素B1（Aflatoxin B1,AFB1）-DNA加合物的表达和p53第249密码子突变情况及其关系,探讨AFB1长期暴露与人群原发性肝细胞癌（hepatocellular carcinoma,HCC）发生的关系。方法实验组为广西医科大学第一附属医院肝胆外科收治的63例HCC患者行根治性手术切除的肝肿瘤组织。按肿瘤大小分为小肝癌组（≤5cm）和大肝癌组（〉5cm）,同时小肝癌组包括两个亚组Ⅰ组（≤3cm）和Ⅱ组（〉3cm）。另取10例来自肝移植供肝及肝外伤切除的正常肝组织作为正常对照组。通过免疫组织化学（immunohistochemistry,IHC）法检测各组样本AFB1-DNA加合物的表达,并以PCR结合直接测序的方法检测其p53第249密码子的突变情况。结果小肝癌组的AFB1-DNA加合物阳性率最高（73.8%）,显著高于大肝癌组（P=0.016）。而小肝癌组p53第249密码子的突变率（35.7%）却显著低于大肝癌组（P=0.007）。正常对照组AFB1-DNA加合物阳性率为50.0%,但未发现p53第249密码子存在突变。Ⅰ组与Ⅱ组之间无论是AFB1-DNA加合物阳性率还是p53第249密码子的突变率差异均无统计学意义（P1=0.676,P2=1.000）。实验组中,33.3%的样本为AFB1-DNA加合物和p53第249密码子突变双阳性,22.2%的样本为AFB1-DNA加合物和第249密码子突变双阴性。结论广西为AFB1高污染地区,正常人群普遍存在AFB1的暴露。AFB1的暴露可增加HCC的发病概率。p53第249密码子突变可能是影响AFB1相关HCC发生、发展的因素。结合AFB1-DNA加合物表达和第249密码子突变的情况,可有效地了解肝癌患者长期持续性或非持续性的AFB1暴露下DNA的累积损伤情况。     

肝硬化及肝癌p53基因突变的实验研究

目的 :研究肝硬化及肝癌p53基因的突变情况。方法 :选择 80例肝硬化、肝癌标本 ,分别以PCR SSCP法 ,双链DNA序列测定法研究其p53基因外显子的突变情况及突变位点。结果 :62例肝癌标本p53总突变率为 19 4 % ,其中 ,早、中、晚期突变率分别为 10 5%、15 0 %、35 0 % ;18例肝硬化标本p53总突变率为 5 6% ;第 7外显子的突变发生在 2 4 9位密码子第 3号碱基上 ,为G :C→T :A的颠换突变 ;第 8外显子的突变发生在 2 73位密码子第 1号碱基上 ,为C :G→T :A的转换突变。结论 :p53基因突变发生在肝细胞发生形态学改变之初 ,随着肝癌的进展逐渐积累 ,突变率呈上升趋势 ,故p53基因突变很可能是启动癌变过程的重要因素之一。     

肝硬化及肝癌p53基因突变的实验研究

目的：研究肝硬化及肝癌p53基因的突变情况。方法：选择80例肝硬化、肝癌标本,分别以PCR－SSCP法,双链DNA序列测定法研究其p53基因外显子的突变情况及突变位点。结果：62例肝癌标本p53总突变率为19．4％,其中,早、中、晚期突变率分别为10．5％、15．0％、35．0％;18例肝硬化标本p53总突变率为5．6％;第7外显子的突变发生在249位密码子第3号碱基上,为G：C→T：A的转换突变。结论：p53基因突变发生在肝细胞发生形态学改变之初,随着肝癌的进展逐渐积累,突变率呈上升趋势,故p53基因突变很可能是启动癌变过程的重要因素之一。     

启东肝癌高发区肝癌患者血清中p53突变研究

目的　研究启东地区肝癌患者血清中 p5 3基因突变 ,并确定其对肝癌诊断的意义。 方法　收集 2 5例肝癌 ,2 0例肝硬化 ,30例健康对照者的血标本 ,提取DNA ,应用限制性酶切及直接序列分析方法测定 p5 3基因第七外显子突变。 结果　显示 p5 3基因第七外显子的 2 49密码子产生突变 ,ARG变为SER ,肝癌 ,肝硬化 ,健康者中发生率分别为 44 % ( 11/2 5 ) ,2 0 % ( 4/2 0 ) ,7% ( 2 /30 ) (P <0 .0 1)。结论　启东地区肝癌患者血清中p5 3突变与肝癌发生密切相关 ,其可作为新的肝癌早期诊断标志。     

肝细胞癌p53基因突变及其临床意义

抑癌基因p53具有广谱抑癌作用，该基因失活是细胞发生癌变的重要因素。p53基因失活的机制是多种的，其中突变是其失活的主要原因之一〔1〕。第7外显子是p53基因突变的热点区之一，在黄曲霉毒素高污染区的肝癌存在该外显子第249位密码子特异突变〔2〕。本实验应用PCR－SSCP同位素技术和PCR直接序列分析对我国重庆地区肝细胞癌p53基因第7外显子突变进行检测，并探讨其临床意义。1材料和方法1．1临床资料28例肝细胞癌均为我院肝胆外科住院病人并长期居住本地，男24例，女4例，年龄21～73岁，平均48岁。有肝炎、肝硬化史24例，长期饮酒史5例…     

中国高发区肝细胞癌p53基因热点突变的规律性

目的 研究同发区肝细胞癌（ＨＣＣ）Ｐ５３基因２４９密码子高频度突变的规律性,为探寻癌及基于Ｐ５３的基因和免疫治疗提供依据。方法 用巢工ＰＣＲ结合测序和限制性片段长度多态（ＲＦＬＰ）分析的方法,研究１９９４－１９９７年收集的９７例启东和２２便北京的肝细胞癌标本中,Ｐ５３基因２４９密码子的突变率及突变的基因型。用免疫组化法研究癌及癌周细胞中Ｐ５３蛋白的表达程度。 １９９４－１９９７年,启东肝细胞癌中,     

Genetic alterations in hepatocellular carcinomas: association between loss of chromosome 4q and p53 gene mutations.

The major risk factors for hepatocellular carcinomas (HCC) in high incidence areas include infection with hepatitis B and C viruses (HBV, HCV) and exposure to aflatoxin. Genetic alterations in 24 liver resection specimens from Shanghai and Qidong were studied. Hepatitis B virus was integrated in all patient samples, and a null phenotype for the GSTM1 enzyme was present in 63% of patients. Alteration of p53 was present in 95% (23/24) of cases: mutations of the p53 gene in 12 HCC, p53 overexpression in 13 and loss of heterozygosity (LOH) of chromosome 17p in 17. All seven HCCs with a p53 mutation from Qidong and three of five from Shanghai had the aflatoxin-associated point mutation with a G to T transversion at codon 249, position 3. No HCC had microsatellite instability. LOH of chromosome 4q, 1p, 16q and 13q was present in 50%, 46%, 42% and 38%, respectively, and 4q was preferentially lost in HCCs containing a p53 mutation: LOH of 4q was present in 75% (9/12) of HCC with, but only 25% (3/12) of HCC without, a p53 gene mutation (P = 0.01). These data indicate a possible interaction between p53 gene mutation and 4q loss in the pathogenesis of HCC.     

Absence of p53 mutation at codon 249 in duck hepatocellular carcinomas from the high incidence area of Qidong (China)

Dietary aflatoxin and hepatitis B virus infection may play arole in generating the p53 tumor suppressor gene codon 249 hotspotmutation found in human hepatocellular carcinomas (HCCs) fromQidong (China) and southern Africa. No data are available onthe HCC site-specific mutation of the p53 gene in hepadnavirus-infectedanimals exposed to AFB₁. We have searched for the presence ofp53 gene codon 249 mutations in both duck hepatitis B virus(DHBV) positive and negative HCCs of domestic ducks from Qidong,where the human p53 hotspot is so prevalent, as well as in duckHCCs experimentally induced by AFB₁. Direct sequencing of DNAamplification products encompassing p53 codon 249 did not revealany mutations in 11 HCCs from Qidongducks, regardless of thestatus of DHBV infection. In addition no mutation was detectedin four HCCs from AFB₁-treated ducks. This contrasts with thehuman data; however, in humans, the mutation and the preferentialbinding of AFB₁ to codon 249 occurs at the third nucleotideG, while in duck, the codon 249 lacks this G residue. The DNAsequence of adjacent codons is also different in the two specieseven though the amino acid sequence is identical. This may explainthe low frequency of mutation we have observed. In addition,species differences in metabolism and DNA repair could influencethe occurrence of codon 249 mutations.     

中国高发区肝细胞癌中HBVx基因的广泛存在及与p53基因249密码子高 …

目的 乙肝病毒（ＨＢＶ）是肝细胞癌（ＨＣＣ）的主要病因。ＨＢＶ中的ｘ基因被认为是它的癌基因。为确定ｘ基因在肝癌癌变中的重要性,我们主要针对ＨＢｓＡｇ阴性的ＨＣＣ,研究ＨＢＶｘ基因的存在、表达和突挛情况;同时也对ｘ基因与Ｐ５３基因２４９密码子热点突变的相关性进行了分析。方法 应用ＰＣＲ、ＲＴ－ＰＣＲ、ＰＣＲ－ＲＦＬＰ和ＤＮＡ序列分析方法,重点针对１９９１年－１９９６年在启东北京手术的的、病理确诊为Ｈ     

Polymorphism of XRCC1 and the frequency of mutation in codon 249 of the p53 gene in hepatocellular carcinoma among Guangxi population, China

In hepatocellular carcinoma (HCC), hotspot mutation in codon 249 of the p53 gene has been associated with exposure to aflatoxin B1 (AFB1). While the polymorphism of DNA repair gene X-ray repair cross-complementary group 1 (XRCC1) Arg399Gln may be related with AFB1-DNA adducts and gene mutations. Five hundred one HCCs were included in this study to investigate the role of the XRCC1 codon 399 polymorphism on hotspot mutation in codon 249 of the p53 gene. The genotypes of XRCC1 codon 399 and p53 codon 249 were examined by PCR-RFLP. The HCC patients with XRCC1 genotypes with 399 Gln (namely: XRCC1-AG/GG) exhibited a significantly higher frequency of the p53 hotspot mutations in codon 249 than those with the wild-type homozygote of XRCC1 [namely: XRCC1-AA, adjusted odds ratio (OR) = 6.77, 95% confidence interval (CI) = 4.34-10.57]. Compared with those individuals who did express XRCC1-AA as reference (OR = 1), moreover, individuals featuring XRCC1-AG/GG and AFB1-DNA adducts did experience a significantly greater frequency of the hotspot mutation in codon 249 of the p53 gene (adjusted OR = 28.37, 95% CI = 13.19-61.02, P < 0.01). This study suggests that the XRCC1 Arg399Gln polymorphism and AFB1-DNA adducts are associated with the increased frequency of the p53 mutations in codon 249.     

乙肝病毒/黄曲霉毒素B1双暴露相关性肝细胞癌的p53基因249位点突变与p53蛋白表达的关系

目的研究乙肝病毒/黄曲霉毒素B1双暴露相关性肝细胞癌的p53基因249位点突变与p53蛋白表达关系。方法通过IHG特殊免疫组织化学法检测55例手术切除经病理证实为原发性肝癌的HCC组织及10例正常肝组织中AFB1-DNA加合物的暴露情况,并根据是否同时存在HBV暴露加以分组,通过免疫组化S-P法检测并比较各组间p53蛋白的表达情况。同时,通过PCR结合直接测序的方法检测其p53基因第7外显子249密码子的突变情况。结果 p53基因第7外显子249位点的突变在实验组A与对照组C中均具有较高阳性突变率,其突变率分别为68.75%（22/32）、63.64%（7/11）,在对照组B中的突变率较低,为16.67%（2/12）,在正常对照组中无1例出现有突变。其中实验组A与对照组B及正常对照组D的比较差异具有统计学意义（P〈0.05）,而与对照组C比较差异无统计学意义（P〉0.05）;p53蛋白在其基因249位点突变阳性组与阴性组中的表达阳性率分别为92.86%（26/28）、60.87%（16/27）,差异具有统计学意义（P〈0.05）。结论 HCC的发生过程中,AFB1暴露与p53第7外显子249位点的突变密切关系相关,当同时存在乙肝病毒暴露的协同作用的情况下突变率更高;p53基因的突变可能是造成HCC中p53蛋白高表达的重要因素之一。     

Low frequency of p53 gene mutation in tumors induced by aflatoxin B1 in nonhuman primates.

Aflatoxin B1 has been suggested as a causative agent for a G to T mutation at codon 249 in the p53 gene in human hepatocellular carcinomas from southern Africa and Qidong in China. To test this hypothesis, nine tumors induced by aflatoxin B1 in nonhuman primates were analyzed for mutations in the p53 gene. These included four hepatocellular carcinomas, two cholangiocarcinomas, a spindle cell carcinoma of the bile duct, a hemangioendothelial sarcoma of the liver, and an osteogenic sarcoma of the tibia. None of the tumors showed changes at the third position of codon 249 by cleavage analysis of the HaeIII enzyme site at codon 249. A point mutation was identified in one hepatocellular carcinoma at the second position of codon 175 (G to T transversion) by sequencing analysis of the four conserved domains (II to V) in the p53 gene. These data suggest that mutations in the p53 gene are not necessary in aflatoxin B1 induced hepatocarcinogenesis in nonhuman primates. The occurrence of mutation in codon 249 of the p53 gene in selective samples of human hepatocellular cancers may indicate involvement of environmental carcinogens other than aflatoxin B1 or that hepatitis B virus-related hepatitis is a prerequisite for aflatoxin B1 induction of G to T transversion in codon 249.     

Novel adenine adducts, N7-guanine-AFB1 adducts, and p53 mutations in patients with schistosomiasis and aflatoxin exposure

INTRODUCTION: The most frequent mutation in human hepatocellular carcinoma (HCC) in populations exposed to a high dietary intake of aflatoxin B1 (AFB1) is a mutation in codon 249 of the p53 gene. Schistosomiasis is known to cause p53 mutation. We hypothesized that the combination of schistosomiasis and aflatoxin B1 increases the incidence of p53 gene mutation. METHODS: Liver tissue from 21 patients with schistosomiasis and 5 patients without schistosomiasis were analyzed for occurrence of mutations of the p53 gene and levels of N7-guanine-AFB1 adducts. RESULTS: The presence of mutations in codon 249 of p53 gene was higher in patients infected with Schistosoma haematobium (S. haematobium) than in those infected with Schistosoma mansoni (S. mansoni) or a combination of both strains (p < 0.01), compared to control subjects. No mutations were detected in p53 gene in liver DNA from schistosomiasis-free patients. Significant amounts of N7-guanine-AFB1 adducts and novel adenine-adducts (p < 0.01) were detected in patients with schistosomiasis, mostly in patients infected with S. haematobium or a combination of both strains, compared to control subjects. Conclusion: These data suggest that schistosomiasis and exposure to aflatoxin B1 act synergistically to increase the incidence of p53 gene mutation. The increase in p53 mutations may enhance progression of HCC at an early age in patients with schistosomiasis.