PJ综合症相关抑癌基因LKB1/STK11的逆转录PCR法克隆及序列分析

从正常人胎盘组织中克隆出人野生型PJ综合症相关抑癌基因LKB1/STK11cDNA片段.以提取的总RNA为模板,采用逆转录法获得cDNA第一条链,采用94℃变性、72℃退火及延伸的特殊条件,经PCR扩增出抑癌基因LKB1/STK11cDNA片段,克隆到T载体,在国内首次报道了LKB1/STK11基因的克隆.序列分析表明,该cDNA全长1299bp,与GenBank中人野生型LKB1cDNA编码序列完全相同,证实获得了人野生型抑癌基因LKB1/STK11的cDNA克隆.LKB1/STK11cDNA的成功克隆为其原核表达载体的构建和LKB1/STK11蛋白在细胞内的作用及其抑癌效果、抑癌机理的研究打下了基础.     

Mutations analysis of STK11 ene in Chinese families with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominantly inherited disease characterized by multiple gastrointestinal hamartomatous polyps and melanin spots on lips and buccal mucosa, with an increased risk for various cancers. ThePJS gene, a potential tumour suppressor gene, encoding a serine/ threonie kinase (STK11), was mapped to chromosome 19p13.3. To investigate the mutations of STK11 gene in Chinese with PJS, we analyzed its coding sequence in fifteen patientsand twenty unaffected members of six families, including three multigenerational families with PJS and three sporadic families with PJS, by PCR, PCR-DHPLC and DNA sequencing techniques. Ten point mutations were found in the six families, including five missense mutations, one acceptor-splice site mutation, a nonsense mutation and three silent mutations. Our data showed that five missense mutations occurrd at codon 123 (CAG to CAT) in exon 2, codon 161 (ATT to AGT) in exon 4,codon 194 (GAC to GAG) in exon 4, codon 245 (CTC to TTC) in exon 5 and codon 354 (TTC to TTG) in exon 8. One kind of nonsense mutation was detected at codon 37(CAG to TAG) in exon 1. Furthermore, we found an intronic mutation at a splice-acceptor site: a one base substitution from AG to AA in intron 4. These mutations were not detected in 20 normal DNA samples. In three sporadic families, only in one patient, we detected a missense mutation in exon 5. In addition, we found three silent mutations, which may cause polymorphisms of STK11 gene in introns 1(+36), 3(-51) and 5(+27). These results indicated that the point mutation in STK11 might be involved in PJS pathogenesis. Mutation frequency is higher in the families suffering PJS in three or more generations than that of the sporadic cases.     

Interaction of hepatitis B virus with tumor suppressor gene p53: its significance and biological function

The mechanism of the interaction of hepatitis B virus (HBV) with tumor suppressor p53 and its role in the hepatocar-cinogenesis have been studied by PCR-directed sequencing, gel shift assays and in situ ultraviolet cross-linking assay. The biological function of the interaction of HBV with p53 gene was investigated by co-transfection of chloramphenicol acetyltransferase ( CAT) reporter gene. p53 and HBV DNA. and quantitative PCR. Among the 16 primary hepatocellular carcinoma (PHC) samples. 13 were HBV-DNA positive. 10 HBxAg positive and 9 p53 protein positive. The p53 gene point mutation was found in 5 samples, one of which had a G to T substitution located at codon 249. After analyzing the HBV genome by a computer program, a p53 response element binding sequence was found in HBV genome at upstream of enhancer I. from 1047 to 1059 nucleotides. This sequence could specifically bind to p53 protein, increase p53 protein accumulation in the PHC cells and stimulate the transactivating activity of p53 and HBV replication . The results also revealed that HBxAg could combine with p53 protein to form a complex in the cells and enhance CAT expression. Immunocytochemical staining showed that p53 protein complex was located in the cytoplasm and the process of p53 entry to nuclei was. in part, blocked. From our results, we conclude that the mutation of p53 gene at codon 249 is infrequent in HBV-associated PHC. the DNA-protein binding between HBV and p53. and the protein-protein binding between HBxAg and p53 might lead to the reduction or inactivation of p53 protein, which in turn resulting in HBV-associated hepatocarcinogenesis.     

p53振子的形成机制及microRNA对p53目标基因表达的精细调控

肿瘤抑制因子p53调控着大量的基因,在肿瘤抑制中起着关键作用.实验结果表明,当DNA受损后,p53的表达呈现周期性振荡.已有的一些p53振子的理论模型,其振子产生机制通常依赖于p53和Mdm2之间相互作用的时滞因素.考虑基因表达的转录和翻译过程,运用动力学方程建模的方法,给出一种新模型,并利用Hopf分叉理论,给出p53振子产生的条件.数值模拟结果表明,与已有的时滞模型相比,该模型对参数具有更好的鲁棒性,较好地解释了p53振子的产生机制.最近的许多实验表明,p53调控着miR-34家族中大量microRNA的表达,这些microRNA又在后转录水平上对p53的下游目标基因起着调控作用.在这一模型基础上,研究microRNA加入p53调控网络后所起的调控作用,数值模拟结果初步表明,microRNA对p53下游目标基因表达起到了精细调控作用.     

早期肺癌病人血液中P53的克隆及其pEGFP-N1-p53的构建

首先用RT-PCR方法从早期肺癌病人的外周血中克隆出人抗癌基因p53,经测序确认为野生型后,通过酶切、连接、转化构建出扩增质粒pMD18-T-p53,然后构建出含增强型绿色荧光蛋白(EGFP)基因的真核表达质粒pEGFP-N1-p53.pEGFP-N1-P53经限制性内切酶Hind Ⅲ和BamH Ⅰ酶切,酶切产物电泳结...     

p53蛋白与肝细胞癌临床病理特征及预后的关系

目的 探讨p53蛋白表达与肝细胞癌的临床病理特征及预后的关系,为术后综合治疗及判断预后提供依据。方法 采用免疫组织化学方法检测88例肝细胞癌组织中p53蛋白的表达,比较阳性患者和阴性患者的临床病理因素和术后累积复发率、术后累积生存率的差异。结果 p53蛋白表达阳性组1、2、3累积生存率分别为75．0％、54.4%、24．2％,阴性组相应的分别为84．3％、77．8％、56．1％。与阴性组相比,p53蛋白阳性组有较高的术前AFP浓度（P=0．005）、有较大的肿瘤最大直径（P=0．042）、肿瘤包膜不完整或无包膜者多见（P=0．023）。结论 p53蛋白是评价肝细胞癌恶性程度及预后的一个有价值的生物学指标。     

头颈部鳞癌中p53-mdm2基因异常的研究

目的:检测头颈部鳞癌患者p53基因突变、mdm2基因扩增的状况,了解其与头颈部鳞癌患者的性别、鳞癌分级、淋巴结转移等的相关性及两异常基因的相关性。方法:收集50例行手术切除的头颈部鳞癌患者的新鲜肿瘤组织及其相应的癌旁正常组织,提取标本DNA;用PCR-SS-CP-银染法检测p53基因第5~8外显子的突变状况;用dPCR法检测mdm2基因扩增情况;采用SPSS 10.0统计软件包行2检验分析实验结果。结果:在50例头颈部鳞癌患者标本中,检测出17例存在p53基因突变,突变率为34%,所有的癌旁正常组织未发现p53基因突变;在50例鳞癌标本中检测出6例标本存在mdm2基因扩增,扩增率为12%,其中有一例同时存在p53基因突变;p53基因突变、mdm2基因扩增与患者的鳞癌分级、淋巴结转移、性别等相关性分析结果均无统计学意义(P>0.05)。结论:p53基因突变与mdm2基因扩增在头颈部鳞癌中较常见,可能是头颈部鳞癌发生发展的主要分子机制。     

CTCF通过抑制p53信号通路促进胆管癌细胞的生长、迁移和侵袭

为了探索CCCTC结合因子(CCCTC-binding factor, CTCF)对人胆管癌细胞的生长、迁移和侵袭能力的影响及其潜在的分子作用机制,利用慢病毒感染法获得稳定过表达或敲低CTCF的胆管癌细胞系,采用蛋白质免疫印迹法(Western blotting, Wb)检测CTCF蛋白表达水平,采用Cell Counting Kit-8(CCK-8)法和克隆形成实验检测细胞生长情况,采用Transwell小室实验检测细胞迁移和侵袭能力,采用GraphPad软件(v6)的Mann-Whitney U检验分析CTCF基因在癌和癌旁组织间的mRNA差异表达.结果显示:过表达CTCF可显著促进HCCC-9810和RBE胆管癌细胞的生长、迁移和侵袭能力;敲低CTCF呈现相反的表型.通过通路富集分析发现:CTCF的表达水平在胆管癌中与p53信号通路活性显著负相关,过表达CTCF可显著下调p53及其靶基因p21的mRNA和蛋白表达水平,而敲低CTCF则显著促进p53和p21的mRNA和蛋白表达水平.综上,本研究揭示CTCF可能通过抑制p53信号通路而促进胆管癌细胞生长、迁移和侵袭而发挥促癌基因的功能.     

肿瘤转移相关基因CD44v6与p53在胃癌组织中的表达和预后

目的探讨肿瘤转移促进基因CD44v6和肿瘤转移抑制基因p53在胃癌组织中的表达与预后.方法45例浸润性胃癌组织来自哈尔滨医科大学附属第二医院病理科.采用sABC方法进行CD44v6和p53免疫组织化学检测.结果CD44v6在胃癌组织中表达率为53.3%(24/45).其中低分化腺癌伴印戒细胞癌的表达率高(16/24,66 7%).p53在胃癌组织中的表达率为75.6%(34/45),而在组织学的分型方面无明显差别.结论p53是最先参与肿癌侵袭和转移的抑癌基因.CD44v6具有在不同组织学类型的胃癌中表达率不同的特点,结果表示CD4v6的表达率可判断不同组织学类型胃癌的预后.     

BRC2基元的合成及与靶肽p53(171-192)的相互作用

乳腺癌易感基因2(Breast Cancer Susceptibility Gene 2,BRCA2)是能抑制细胞发生恶变的关键基因.p53蛋白是参与细胞过程的主调控蛋白,p53蛋白要想行使其功能,则需要BRCA2及其产物对p53进行调控.选择BRCA2中的BRC2重复基元,用Fmoc固相合成法合成了BRC2及其3个片段.通过反相高效液相色谱(RPHPLC)和质谱对其进行表征,得到纯度大于90%的目标肽链.利用圆二色谱法初步探究了BRC2及其3个片段与靶肽p53(171-192)的相互作用.结果表明,BRC2的3个肽片段中,片段NEVGFRGFYSAHG在BRC2肽行使其功能中起着主要的作用.     

脊椎动物促性腺激素释放激素的结构、基因表达与调控的研究进展

综述了有关对脊椎动物促性腺激素释放激素的结构、基因表达与调控的研究进展 .阐明促性腺激素释放激素结构多样性 ,功能多样性 ,及其基因表达与调控 ,并对可能的应用前景作简要阐述     

p53-dependent upregulation of PIG3 transcription by γ-ray irradiation and its interaction with KAP1 in responding to DNA damage

PIG3 (p53-inducible gene 3), originally identified as one of a set of genes induced by p53 before the onset of apoptosis, was assumed to contribute to early cellular response to DNA damage. Here, we studied the relation between p53 status and the increased expression of PIG3 by ionizing radiation (IR), and the related clues regarding the involvement of PIG3 in the cellular response to IR-induced DNA damage signaling. We demonstrated that the pentanucleotide microsatellite sequence was responsible for the p5...