胃癌组织中P53基因缺失、重排和点突变的研究

本文用Southern杂交方法分析了30例胃癌组织中P53基因的缺失和重排,发现9例(30％)有缺失或重排;用PCR-RFLP方法分析了胃癌组织中P53基因第248、249位密码子的点突变,42例中2例(4.8％)有248位密码子的点突变。     

非放射性PCR-LIS-SSCP技术快速分析肝癌患者p53基因249位密码子的突变

目的应用非放射性PCR-LIS-SSCP方法快速分析肝癌患者p53基因第249位密码子突变.方法采用PCR-LIS-SSCP方法,研究了16例来自中国广西、江苏启东和上海地区肝癌患者p53基因第249位密码子的突变情况,并用限制性内切酶和DNA测序对PCR-LIS-SSCP方法所获得的结果进行了验证.结果从16例肝癌病人中检出3例在该位点具有突变.其中广西地区的4例肝癌病人有1例发生突变,江苏启东地区的4例肝癌病人有1例发生突变,上海地区的8例肝癌病人有1例发生突变. 结论用该方法检测肝癌病人p53基因第249位密码子突变频率为18.8%(3/16),为该方法应用于候选新基因的未知突变研究奠定了基础.     

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.     

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。     

肝细胞癌中mdm2基因表达与p53基因失活有关

mdm2基因与p53基因间存在相互调节网络,可望成为基因治疗的靶基因,本文应用反转录PCR反应、PCR联合限制性内切酶反应方法,研究了42例癌组织和25例癌周肝组织中mdm2基因表达与p53基因第七外显子第249密码子突变的相互关系.结果提示mdm2基因表达值(均数±标准误)在p53基因未突变肝癌组(62.1%±8.4%)高于p53基因突变肝癌组(38.5±4.8%,P<0.5),也高于癌周肝组织(p53基因无突变)(26.2%±5.1%,P<0.01),而在p53基因突变组(38.5±4.8%)与癌周肝(26.2%±5.1%,P>0.05)间无明显差别.病灶多发肝癌与病灶单发肝癌相比,mdm2基因表达值(均数±标准误)在病灶多发组(68.9%±10.1%)明显高于病灶单发组(42.6±4.2%,<0.05),而p53基因第249密码子突变率则明显差别(40%对44%,P<0.05).     

PCR-SSCP法检测宫颈癌P53基因突变

 目的：探讨抑癌基因P⁵³突变与宫颈癌发生发展之间的关系,并为该病的临床检测提供一种分子生物学方法。方法：应用多聚酶链反应－单链构象多态性（PCR SSCP）分析方法对宫颈癌及慢性宫颈炎组织中P⁵³基因5～6外显子的突变进行了检测。结果：35例宫颈癌组织中有2例出现突变,突变率为5.71%;而作为对照的慢性宫颈炎组织中无一例出现突变。结论：宫颈癌的发生与抑癌基因P⁵³5～6外显子的突变有关;此方法可有效地检测抑癌基因P⁵³的突变。     

SRRS方剂抑制消化道恶性肿瘤P53基因突变的实验研究

 目的：从分子水平探讨SRRS方剂治疗消化道癌的可能机制。方法：选用Lovo结肠腺癌细胞裸小鼠移植瘤模型,观察中药SRRS方剂抑制移植瘤生长的作用,并用PCR-SSCP银染色法研究SRRS方剂对Lovo移植瘤生长过程中P⁵³基因突变的影响情况。结果：对照组有50%(5/10)发生P⁵³基因第七外显子突变,SRRS方剂治疗组无(0/10)此现象(P<0.05)。结论：提示SSRS方剂能抑制lovo移植瘤生长过程中P⁵³基因的突变,即SRRS方剂可对肿瘤生长过程中肿瘤细胞的基因水平有影响作用。     

P53突变产物在睑板腺癌中的增强表达及其意义

 我们采用免疫组化S-P法, 对17例石蜡包埋睑板腺癌及癌旁组织标本的P⁵³突变蛋白表达进行了检测。 结果:17例癌组织有12例表达阳性, 阳性率71%。其中分化型7例, 6例呈阳性(86%)表达。在一组原发灶及淋巴结转移癌配对标本中, 同一病人之两个部位P⁵³突变蛋白表达差异无明显意义。 癌旁(睑缘)组织17例中5例上皮有异常增生, 且同时伴有P⁵³突变蛋白呈强阳性表达。 以上结果提示:抑癌基因P53的突变在睑板腺癌的发生中是一个比较常见的基因改变, 且在分化型癌的发生中表现明显; P⁵³基因异常发生在肿瘤转移之前且在淋巴道转移中可能起重要作用; P⁵³突变蛋白在癌旁上皮异型增生组织中的过度表达具有十分重要的意义。     

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。     

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,     

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.     

Mutability of p53 hotspot codons to benzo(a)pyrene diol epoxide (BPDE) and the frequency of p53 mutations in nontumorous human lung

p53 mutations are common in lung cancer. In smoking-associated lung cancer,the occurrence of G:C to T:A transversions at hotspot codons, e.g., 157, 248, 249,and 273, has been linked to the presence of carcinogenic chemicalsin tobacco smoke including polycyclic aromatic hydrocarbons suchas benzo(a)pyrene (BP). In the present study, we have used a highly sensitive mutation assay to determine the p53 mutation load in nontumorous human lung and to study the mutability of p53 codons 157, 248, 249, and 250 to benzo(a)pyrene-diol-epoxide (BPDE), an active metabolite of BP in human bronchial epithelial BEAS-2B cells. We determined the p53 mutational load at codons 157, 248, 249, and 250 in nontumorous peripheral lung tissue either from lung cancer cases among smokers or noncancer controls among smokers and nonsmokers. A 5-25-fold higher frequency of GTC(val) to TTC(phe) transversions at codon 157 was found in nontumorous samples (57%) from cancer cases (n = 14) when compared with noncancer controls (n = 8; P < 0.01). Fifty percent (7/14) of the nontumorous samples from lung cancer cases showed a high frequency of codon 249 AGG(arg) to AGT(ser) mutations (P < 0.02). Four of these seven samples with AGT(ser) mutations also showed a high frequency of codon 249 AGG(arg) to ATG(met) mutations, whereas only one sample showed a codon 250 CCC to ACC transversion. Tumor tissue from these lung cancer cases (38%) contained p53 mutations but were different from the above mutations found in the nontumorous pair. Noncancer control samples from smokers or nonsmokers did not contain any detectable mutations at codons 248, 249, or 250. BEAS-2B bronchial epithelial cells exposed to doses of 0.125, 0.5, and 1.0 microM BPDE, showed G:C to T:A transversions at codon 157 at a frequency of 3.5 x 10(-7), 4.4 x 10(-7), and 8.9 x 10(-7), respectively. No mutations at codon 157 were found in the DMSO-treated controls. These doses of BPDE induced higher frequencies, ranging from 4-12-fold, of G:C to T:A transversions at codon 248, G:C to T:A transversions and G:C to A:T transitions at codon 249, and C:G to T:A transitions at codon 250 when compared with the DMSO-treated controls. These data are consistent with the hypothesis that chemical carcinogens such as BP in cigarette smoke cause G:C to T:A transversions at p53 codons 157, 248, and 249 and that nontumorous lung tissues from smokers with lung cancer carry a high p53 mutational load at these codons.     

p53 mutations cluster at codon 249 in hepatitis B virus-positive hepatocellular carcinomas from China.

DNA samples from 36 hepatocellular carcinoma (HCC) patients from China were screened for a specific mutation affecting codon 249 of the p53 gene, recently identified as a hotspot mutation in some HCCs. We detected the tumor-specific p53 codon 249 mutation in 21 (58%) of 36 HCCs examined. Thirteen patients with the specific codon 249 mutation had lost the remaining allele of p53, whereas the remaining eight patients appeared to have retained both copies of the gene. These results suggest that alterations of p53 may be important events in the genesis of HCCs and that point mutation may precede allele loss.     

High prevalence of mutations at codon 249 of the p53 gene in hepatocellular carcinomas from Senegal.

In hepatocellular carcinoma, mutation within the p53 gene occurs mainly at codon 249 and its frequency has been associated with exposure to aflatoxin. As Senegal is a country where liver cancer incidence is one of the highest in the world and where people are highly exposed to aflatoxin, we screened 15 liver cancer samples from this country for mutation at codon 249 of the p53 gene. Non-tumoral DNA from the patients showed a wild type genotype. Mutation at codon 249 of the p53 gene was detected in 10 of the 15 tumour tissues tested (67%). This frequency of mutation in codon 249 of the p53 gene is the highest described. These results confirmed that there is an association between countries of high aflatoxin intake and a high frequency of mutation in codon 249 of p53 gene, and that HBV alone does not contribute to these base changes.     

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。     

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.     

P53 mutations may be related to tumor invasiveness of human hepatocellular-carcinoma in china

A combined polymerase chain reaction (PCR) with the enzyme HaeIII restriction analysis and DNA sequencing have been employed to study the mutations at codon 249 of p53 gene in two human hepatocellular carcinoma (HCC) cell lines and 28 surgical specimens of HCC. 14 of the 28 HCC samples (50%) had p53 point mutations at codon 249. All of point mutations at codon 249 in 10 cases sequenced are AGG to AGT transversion. p53 gene mutated more frequently in invasive HCCs than that in non-invasive HCCs. This suggested that the codon 249 was a mutational hotspot of p53 gene in human HCCs in China, and p53 mutations may be related to tumor invasiveness of human HCC.