肝细胞肝癌相关新基因FP248的功能研究

目的FP248基因是本实验室通过高通量基因功能筛选得到的一个与细胞生长相关的新基因,本研究旨在研究其在肝癌发生发展中的作用.方法用Northern blot,Southern blot方法检测FP248在肝癌及其癌旁组织中mRNA表达差异和DNA的变化.通过体外细胞转染和体内裸小鼠成瘤实验观察FP248对肝癌细胞SMMC-7721生长的作用,并用Atlas Hu-man cDNA Expression Array探讨FP248影响肝癌细胞SMMC-7721的作用机理.结果FP248的mRNA在57%(4/7)的肝癌中表达高于其相应的癌旁组织,而且肝癌组织中DNA有扩增.FP248的过表达在体内外均可明显促进SMMG-7721细胞的生长.Atlas结果显示FP248过量表达后可上调许多与细胞生长密切相关的基因,同时还参与调节细胞粘附分子.结论基因FP248与肝癌的发生发展有密切关系,是一个与人肝癌发生发展相关的新基因.     

HOXB7基因敲除对人肝癌细胞的增殖、侵袭及迁移能力的影响

目的 研究同源异型盒基因HOXB7（Homebox7）对人肝癌细胞增殖、侵袭、迁移能力的影响及部分机制。方法 采用荧光定量PCR法选取HOXB7 mRNA高表达的人肝癌SMMC-7721细胞和HepG2细胞;设计靶向HOXB7的shRNA,瞬时转染肝癌SMMC-7721细胞,荧光定量PCR和Westernblot法检测shRNA靶向沉默的效果,CCK8、Transwell和划痕实验分别用于检测细胞增殖、侵袭和迁移能力;Western blot法测量肝癌SMMC-7721细胞中Smad3、p-Smad3表达水平。结果 HOXB7 shRNA转染的肝癌SMMC-7721细胞中HOXB7基因mRNA和蛋白表达水平均显著降低,同时细胞增殖、侵袭和迁移能力随之下降,且TGF-β通路中p-Smad3蛋白表达水平下调。结论 HOXB7可促进肝癌细胞增殖、侵袭以及迁移能力,其机制可能与调节Smad3磷酸化水平有关。     

人剪切修复基因XPD转染对人肝癌细胞SMMC-7721的生物学影响

目的 将人剪切修复基因XPD稳定转染人SMMC-7721肝癌细胞,观察转染后细胞内野生型p53、XPD、周期素依赖性蛋白激酶(CDK)7、c-myc等基因表达的变化以及对细胞生长的影响,探讨野生型XPD基因与p53、CDK7、c-myc的相互作用及细胞凋亡机制.方法 将表达绿色荧光蛋白并含有人类全长野生型XPD的pEGFP-N2-XPD重组体质粒稳定转染人SMMC-7721肝癌细胞中,选择培养基筛选单克隆稳定转染重组质粒的人SMMC-7721肝癌细胞(SMMC-7721-pEGFP-N2-XPD)和稳定转染空载质粒的人SMMC-7721肝癌细胞(SMMC.7721-pEGFP-N2),并将人SMMC-7721肝癌细胞作为空白对照,利用荧光显微镜观测绿色荧光蛋白表达,用逆转录-聚合酶链反应(RT-PCR)、Westem blot法检测转染XPD基因后细胞内XPD、p53、CDK7、c-myc的表达量变化,并用细胞增殖力检测(MTT)法及流式细胞仪分别检测细胞增殖及凋亡和细胞周期变化.结果 ①免疫荧光显微镜下,SMMC.7721.pEGFP.N2.XPD和SMMC-7721-pEGFP-N2细胞中观察到绿色荧光蛋白表达,说明pEGFP-N2-XPD重组质粒和pEGFP-N2空载质粒成功转染.②RT-PCR检测:SMMC-7721-pEGFP-N2-XPD中p53 mRNA、XPD mR-NA表达量与SMMC-7721-pEGFP-N2和SMMC-7721相比均明显增高(P<0.01),CDK7 mRNA、c-myc mRNA在SMMC-7721-pEGFP-N2-XPD的表达量比两对照组明显降低(P<0.01),而两对照组各个基因的表达没有明显差异(P>0.05).③Western blot检测:SMMC-7721-pEGFP-N2-XPD细胞的p53、XPD蛋白表达最较两对照组升高(P<0.01),CDK7、c-myc的蛋白相对表达量比两对照组降低(P<0.01),两对照组差异没有统计学意义(P>0.05).④M1Tr检测:SMMC-7721-pEGFP-N2-XPD的细胞增殖力较对照组减弱(P<0.05),两对照组筹异没有统计学意义(P>0.05).⑤流式细胞仪检测:SMMC-7721-pEGFP-N2-XPD细胞进入s期出现障碍,停滞在G1期的细胞增多.结论 将XPD成功稳定转染到人SMMC-7721肝癌细胞中,XPD、p53在转录和蛋白水平的表达明显升高,CDK7、c-myc表达明显降低,野生型XPD基因的过表达可能抑制CDK7、c-myc表达,改变细胞周期,并促进p53抑制肝癌细胞增长,促进细胞凋亡.     

乙型肝炎病毒X基因经p53依赖性与非依赖性途径对p21WAF1表达的影响

背景与目的:研究表明,在不同情况下乙型肝炎病毒 X基因(HBx)对 p21WAF1的表达具有不同的影响,但作用机制仍不清楚.本研究的目的是探讨 HBx对 p53下游基因 p21WAF1的影响.方法:通过正、反义野生型 p53(wtp53)与 HBx单转染及共转染人肝癌细胞株 SMMC-7721细胞,以及 HBx转染不同内源性 p53状态的肝癌细胞株,检测 p21WAF1启动子荧光素酶基因表达,并用流式细胞仪观察细胞周期的变化 ,Western blot法比较 p53、p21WAF1表达水平的变化.结果:正、反义 wtp53与 HBx 单转染及共转染 SMMC-7721细胞 ,HBx与正义 wtp53共转染组(1.007± 0.098)与单转染正义 wtp53(0.490± 0.012)相比,p21WAF1启动子荧光素酶基因表达明显升高(P< 0.05),其余各组 HBx均可导致 p21WAF1启动子荧光素酶基因表达明显减少(P< 0.05).Western blot法表明 HBx可导致 p53的表达增加,但 p53表达较低的 SMMC-7721细胞转染 HBx后 p21WAF1蛋白的表达减弱 ,p21WAF1启动子荧光素酶基因表达(0.053± 0.010)也较对照组(0.094± 0.013)明显减少(P< 0.05),而 p53表达较强的 HepG2细胞转染 HBx后 p21WAF1蛋白的表达增强、p21WAF1启动子荧光素酶基因的表达(1.252± 0.052)较对照组明显升高(0.767± 0.031)(P< 0.05).细胞周期结果表明瞬时转染 HBx的 SMMC-7721和 Hep3B细胞停滞在 G0-G1期细胞数(42.31%、36.96%)较对照组(47.10%、42.90%)减少,而瞬时转染 HBx的 HepG2细胞(63.62%)停滞在 G0-G1期的细胞数较对照组(57.42%)增加,但稳定筛选后 ,pcDNA3HBxHepG2细胞(57.31%)停滞在 G0-G1期细胞数较对照组(61.49%)减少.结论:HBx一方面可能引起 p53蛋白在细胞内积聚导致 p21WAF1表达升高,另一方面可直接抑制 p21WAF1启动子的转录活性.     

沉默Gli2 基因对肝癌SMMC-7721 细胞增殖和凋亡的影响

目的: 探讨沉默胶质瘤相关癌基因同源蛋白2 基因（glioma associated oncogene homolog 2,Gli2)对肝癌SMMC-7721细胞增殖、凋亡的影响及其可能的作用机制。方法:以重组shRNA-Gli2 慢病毒感染SMMC-7721 细胞,筛选沉默效果最佳干扰序列。以携最佳干扰序列重组慢病毒感染SMMC-7721 细胞为干扰组,shRNA-NC慢病毒感染SMMC-7721 细胞为对照组,不作处理SMMC-7721 细胞为空白组。采用CCK-8 法与集落形成实验检测各组细胞的增殖活性,流式细胞术检测各组细胞凋亡率;用qPCR 和Western blotting 法检测各组细胞Gli2、cyclinD1、Bax 和Bcl-2 mRNA及其蛋白质的表达。结果:重组慢病毒感染率约为90%,重组shRNA-Gli2-1 慢病毒沉默效果最佳;干扰组SMMC-7721 细胞Gli2 mRNA和蛋白质表达显著低于对照组与空白组（均P<0.05）,而对照组与空白组之间Gli2 mRNA和蛋白质表达差异不显著（P>0.05）。干扰组SMMC-7721 细胞的增殖和细胞集落形成数明显少于对照组和空白组（均P<0.05）;干扰组SMMC-7721 细胞凋亡率显著高于对照组和空白组（均P<0.01）;干扰组SMMC-7721 细胞cyclinD1 及Bax mRNA和蛋白质表达显著低于对照组和空白组,而Bcl-2 mRNA和蛋白质表达则显著高于对照组和空白组（均P<0.05）。结论: 沉默Gli2 基因的表达能够抑制肝癌SMMC-7721 细胞增殖,促进肝癌细胞凋亡,其机制可能与cyclinD1、Bax的下调和Bcl-2 上调有关。     

生物节律相关基因 Cry1与肝癌的相关性探讨

目的研究生物节律相关基因Cry1与肝癌发生发展的相关性.方法逆转录PCR、Northern blot和免疫组织化学方法检测Cry1在各种肿瘤细胞系、人正常组织及人肝癌与配对的癌旁组织中的表达.构建Cry1重组的真核表达质粒并转染肝癌细胞SMMC-7721.生长曲线和软琼脂克隆形成试验检测Cry1过表达的SMMC-7721细胞的体外增殖速度.逆转录PCR检测与Cry1相互作用的生物节律基因在Cry1过表达的SMMC-7721中的表达.结果Cry1在人各种正常组织中均有不同程度的表达.Cry1在人肝癌癌旁组织中的表达水平高于癌组织中的表达.过表达Cry1对SMMC-7721细胞的体外增殖没有明显影响.结论生物节律相关基因Cry1与肝癌发生发展可能有一定的相关性.     

lncRNA TUG1对肝癌细胞增殖及自噬水平的影响

目的:检测长链非编码RNA牛磺酸上调基因（taurine upregulated gene 1,TUG1）在肝癌组织中的表达情况,证实TUG1对肝癌细胞增殖和自噬能力的影响。方法:实时定量PCR检测50例肝癌组织标本以及相应癌旁组织中TUG1的表达水平以及在肝癌细胞系中的表达情况。通过将构建的TUG1过表达质粒转染肝癌细胞系SMMC-7721和HepG2,验证转染效率并采用CCK-8法检测肝癌细胞增殖情况;Western blot检测自噬标志蛋白（LC3-Ⅱ/Ⅰ）表达变化;通过实时定量PCR筛选表达差异最显著的自噬相关基因并采用Western blot验证。结果:肝癌组织中TUG1的表达显著高于癌旁组织,差异有统计学意义(P<0.05)。TUG1能够显著促进肝癌细胞增殖能力（P<0.05）;并且过表达TUG1后增加了LC3-I向LC3-Ⅱ的转化,促进自噬水平的发生（P<0.05）;TUG1能够显著上调ATG7的基因和蛋白的表达。结论:在肝癌组织中TUG1表达高于癌旁组织;在体外细胞实验中发现,TUG1能够促进肝癌细胞增殖能力,并通过上调ATG7的表达诱导自噬的发生。     

干扰PRMT2基因对肝癌细胞系生物学行为的影响

目的:研究抑制蛋白质精氨酸甲基转移酶2(protein arginine methyltransferase 2,PRMT2)基因的表达对肝癌细胞系生物学行为的影响。方法:qRT-PCR检测人肝癌细胞系(HepG2和SMMC-7721)和人正常肝细胞(LO2)中PRMT2的表达情况;设计并合成针对PRMT2基因的3对小干扰RNA,体外通过脂质体Lipofectamine 3000转染到相对高表达PRMT2的人肝癌细胞系HepG2和SMMC-7721中抑制PRMT2基因的表达,并设置阴性对照组（NC组）和空白对照组。qRT-PCR、Western blot检测转染后细胞PRMT2 mRNA水平和蛋白水平的变化。CCK-8法检测转染后细胞增殖能力,Transwell小室检测细胞体外迁移及侵袭能力。结果:与人正常肝细胞LO2相比,PRMT2基因在人肝癌细胞系HepG2和SMMC-7721中相对高表达。将siPRMT2转染HepG2和SMMC-7721细胞后,与NC组相比,siPRMT2-1和siPRMT2-2组的PRMT2 mRNA和蛋白表达均明显降低（P均<0.05）,NC组与空白对照组无明显差异。与NC组相比,将siPRMT2-1和siPRMT2-2转染进HepG2和SMMC-7721细胞后,细胞增殖速度减慢、迁移和侵袭能力显著减弱（P均<0.05）,NC组与空白对照组无明显差异。结论:RNA干扰抑制PRMT2表达后,抑制肝癌细胞的增殖、迁移和侵袭,PRMT2可能影响肝癌的预后。     

新基因pp3774的亚细胞定位以及在肝癌细胞系和组织中的表达谱研究

目的探讨新基因pp3774在肝癌细胞系、人肝癌及癌旁肝、肝硬化以及正常肝组织中的表达差异及其生物学功能.方法脂质体转染-荧光观察pp3774-GFP融合蛋白的亚细胞定位;合成新基因pp3774特异性多肽,制备兔源性多克隆抗体;用RT-PCR、蛋白印迹、免疫细胞化学及免疫组化方法检测pp3774基因在7个肝癌细胞系及214例肝细胞癌、18例肝硬化及10例正常肝组织中的表达差异.流式细胞术检测转染pp3774基因的SMMC-7721细胞的凋亡率.结果 pp3774蛋白主要定位于细胞质(内质网为主);RT-PCR检测结果表明pp3774 mRNA在肝癌细胞系BEL-7402、Huh-7、MHCC-97L及HepG2中高表达,SMMC-7721、MHCC-LM3及人永生化肝细胞系L-02中度表达,而在Hep3B中低表达;肝癌及癌旁组织中pp3774 mRNA的表达表现为癌旁高于癌(P<0.05);免疫组化结果显示pp3774蛋白表达程度依次为正常肝≥肝硬化≥癌旁肝组织>肝癌.转染pp3774基因的SMMC-7721细胞的凋亡发生率高于对照组约10%.结论 pp3774基因是一个具有抑制肝癌细胞生长功能的新基因.     

野生型p53对SMMC-7721细胞中POLD1基因的影响

目的探讨野生型p53基因表达对人肝癌细胞SMMC-7721中POLD1基因的影响。方法设计并构建p53特异性小干扰shRNA绿色荧光真核表达质粒（p53-siRNA）和表达EGFP-p53融合蛋白的p53绿色荧光真核增强表达质粒（pEGFP-p53）,通过稳定转染,将表达pEGFP-p53重组质粒、p53-siRNA转染入SMMC-7721细胞;经G418筛选,获得稳定细胞系7721-p53、7721-p53RNAi。通过RT-PCR检测转染后p53、POLD1的mRNA。结果在人肝癌细胞SMMC-7721中,野生型p53高表达组能够抑制POLD1的基因转录（P〈0.001）;而低表达组能够促进POLD1的基因转录（P〈0.001）。结论在人肝癌细胞SMMC-7721中,p53能够调控POLD1的基因转录。     

IL-6和IL-6R在脑胶质瘤发病中的作用初探

目的：初步探讨ＩＬ－６和ＩＬ－６Ｒ与脑胶质瘤发生发展的关系。方法：采用逆转录聚合酶链反应（ＲＴ－ＰＣＲ）方法检测白细胞介素６（ＩＬ－６）和ＩＬ－６受体（ＩＬ－６Ｒ）基因在脑胶质瘤组织标本和正常人脑胶质细胞中的表达。结果：３０例脑胶质瘤组织标本中有２４例（８０．０％）表达ＩＬ－６、２６例（８６．７％）表达ＩＬ－６Ｒ、２２例（７３．３％）同时表达ＩＬ－６和ＩＬ－６Ｒ。人脑正常胶质细胞仅有ＩＬ－６基因弱表达,而玩ＩＬ－６Ｒ表达。结论：脑胶质瘤可能存在与肿瘤的恶性增殖有关的ＩＬ－６／ＩＬ－６Ｒ自分泌或旁分泌环路。     

Repair of oligodeoxynucleotides containing O6-methylguanine by O6-alkylguanine-DNA-alkyltransferase

O⁶-Alkylguanine-DNA-alkyltransferase is a DNA repair proteinknown to carry out the transfer of alkyl groups from the O⁶-positionof guanine in alkylated DNA to a cysteine acceptor site containedwithin its own protein sequence. We have examined the abilityof this protein isolated from either E. coli or mammalian cellsto perform this repair reaction in short oligodeoxynucleotides.Dodecadeoxynucleotides of the sequence 5'-dCGNGAATTCm⁶GCG-3'where N is any one of the normal four bases were all repairedvery rapidly by the protein with 50% repair in < 15 s at0°C. The hexadeoxy-nucleotide 5'-dCGCm⁶GCG-3' was repairedslightly more slowly with 50% removal taking 7 min at 0°Cand 1.5 min at 37°C. The tetradeoxynucleotide 5'-dTm⁶GCA-3'was also a substrate but was repaired much more slowly requiring45 min for 50% repair at 37°C. These results indicate that(a) the AGT has a strong but not absolute preference for double-strandedDNA substrates; (b) the repair of O⁶-methylguanine is independentof the base opposite the lesion; and (c) that oligodeoxynucleotidesas short as tetramers are substrates for repair by this protein.     

Infundibuloma--report of 6 cases

Six cases of rare infundibuloma are reported. Infundibuloma, implying pilocytic astrocytoma which stems from the neurohypophysis, often encroaches upon or injures the neural pathway from the nerve nucleus beneath the hypothalamus to pituitary adenohypophysis. Therefore, various hormones, stimulating or inhibitory, produced by the hypothalamic nerve nuclei could not reach the target cells of adenohypophysis, resulting in different clinical symptoms of dysendocrisiasis. The tumor is difficult to diagnose by X-ray, CT or histopathology because of its miniature size. Regional tomography should be done besides endocrine tests. Specimens should be collected as much as possible during the operation for pathological confirmation. Transoro-nasosphenoidal microsurgery could achieve a good result.     

Characterization of the drug resistance and transport properties of multidrug resistance protein 6 (MRP6, ABCC6)

Mutations in human multidrug resistance protein 6 (MRP6, ABCC6), a member of the MRP family of drug efflux pumps, are the genetic basis of Pseudoxanthoma elasticum, a disease that affects elastin fibers in the skin, retina, and blood vessels. However, little is known about the functional characteristics of the protein, including its potential activity as a resistance factor for anticancer agents. Here, we report the results of investigations of the in vitro transport properties and drug resistance activity of MRP6. Using membrane vesicles prepared from Chinese hamster ovary cells transfected with MRP6 expression vector, it is shown that expression of MRP6 is specifically associated with the MgATP-dependent transport of the glutathione S-conjugates leukotriene C(4) and S-(2, 4-dinitrophenyl)glutathione and the cyclopentapeptide BQ123 but not glucuronate conjugates such as 17beta-estradiol 17-(beta-D-glucuronide). Analysis of the drug sensitivity of MRP6-transfected cells revealed low levels of resistance to several natural product agents, including etoposide, teniposide, doxorubicin, and daunorubicin. These results indicate that MRP6 is a glutathione conjugate pump that is able to confer low levels of resistance to certain anticancer agents.     

Human papillomavirus E6-induced degradation of E6TP1 is mediated by E6AP ubiquitin ligase

High-risk human papilloma viruses are known to be associated with cervical cancers. We have reported previously that the high-risk human papillomavirus (HPV) E6 oncoprotein interacts with E6TP1, a novel Rap GTPase-activating protein (RapGAP). Similar to p53 tumor suppressor protein, the high-risk HPV E6 oncoproteins target E6TP1 for degradation. The HPV16 E6-induced degradation of E6TP1 strongly correlates with its ability to immortalize human mammary epithelial cells. In this study, we used treatment with a proteasome inhibitor MG132, analysis in CHO-ts20 cells with a thermolabile ubiquitin-activating enzyme, and direct detection of ubiquitin-modified E6TP1 to demonstrate that E6TP1 is targeted for degradation by the ubiquitin-proteasome pathway both in the presence and in the absence of E6. Using deletion mutants of E6TP1, we mapped the region required and sufficient for E6 binding to COOH-terminal 40 amino acid residues and showed this region to be necessary for E6-dependent degradation of E6TP1. Furthermore, the E6-binding region of E6TP1 complexes with E6AP via E6. Importantly, the purified E6AP enhanced the ubiquitination and degradation of E6TP1 in the presence of E6 in vitro. Additionally, the expression of a dominant-negative E6AP mutant (C833A) in cells inhibited the E6-induced degradation of E6TP1. These findings demonstrate that the E6-induced decrease in the levels of E6TP1 protein involves the E6AP-mediated ubiquitination followed by proteasome-dependent degradation.