癌基因与抑癌基因

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,oncogene & tumor suppressor gene,Department of Biochemistry and,molecular biology,Zhang Ying,OVERVIEW,Many genes and factors outside of genes is involved in carcinogenesis.,The accumulation of manygenetic changescause cancer other than mutationsof a singlegene bycausing disorders of cell growth and differentiation, thecell proliferationout of control.,Oncogene,antioncogene,tumor metastasis gene,cell,apoptosis,DNA damage and repair, telomerase, microRNA,Relationships of oncogene,tumor suppressor geneand growth factors,oncogene,tumor suppressor gene,cells,Growth factor,Positive regulation,Negative regulation,products,The regulation of gene expression andcell proliferation, differentiation is involved in,the mechanism of oncogenesand tumor suppressor genes,Section I Oncogene,Concept of oncogene,Viral oncongene,Cellular oncogene,The products of oncongene and its fuction,一、,the concept of oncogene,Oncogene,：,the genes in cells is responsible of controlling cellgrowth,proliferation and differentiation. They will cause cellularcancerationwhen their structure or expression turns abnormal.,All of genes which encode for growth factors, growth factor receptors, signal molecules and transcription factors related to growth.,The writing of oncogene,ras,、,src,、,myc,v-,ras,c-,ras,Classification,of oncogene,1,、,virus oncogenes,，,v-onc:,the genes existing in virus (mostly, retrovirus) which cause the target cells maligant transformation, such as v-,src,2,、,Proto-oncogenes or cellular-oncogene, c-onc:,the oncogenes existing in normal genome which are in quiescence or inactive state such as c-myc,、,c-ras,、,c-src,。,Under normal condition,，,these genes are in quiescence or low expression state and not only no harmful to cells but also helpful to stain normal function to cells.,The structural comparison of c-src,and,v-src,二、,V,irus oncogenes,the oncogene existing in virus genome which does not encode the protein of virurs and is not helpful to replication but do make host cell Continuous proliferation,Rous,Peyton,Rous,肉瘤,the structure of,Rous sarcoma virus,1970,Temin and Batimore, reverse transcriptase,，,1975 Nobel,1971, Duesberg, the genome of RSV,gag,LTR,pol,env,LTR,5,Normal virus gene,oncogene,regulating and initiating transcription,the core protein of virus,reverse transcriptase and Integrase,Outer membrane protein,Tyrosine kinase,src,3,1979, H. Varmus,and,J. M. Bishop found that src is,carcinogenesis,in RSV, but also found that the,h,omologs of src exist in animal cells commonly,if,the cDNA of src is,hybridized with other genome DNA. Result: src stem from normal cell genome.,-,1989 Nobel,Voiceover : that is why such RSV retrovirus induce host cell carcinogenesis.,三、,cellular oncogene,（一）,the traits of cellular oncogene,Universality,：,exists in biological widely,；,conservatism,：,The gene sequencewas highly homologous in the process of evolution,Importance,：,the expression protein regulate,cell proliferation,differentiation and apoptosisprecisely,Harmfulness,: the variation of structure and numbers make cell carcinogenesis,the oncogenes existing in normal genome which are in quiescence or inactive state such as c-myc,、,c-ras,、,c-src,。,Under normal condition,，,these genes are in quiescence or low expression state and not only no harmful to cells but also helpful to stain normal function to cells.,family member action location,src,家族：,src,、,abl,、,fgr,、,fes,、,TPK,活性,膜内侧或跨膜,yes,、,fps,、,lck,、,kek,、（,酪氨酸蛋,fym,、,lyn,、,tkl,白激酶）,ras,家族：,H-ras,、,K-ras,、,N-ras,G,蛋白,( P21),膜内侧,myc,家族：,c-myc,、,N-myc,、,L-myc,结合蛋白 核内,jun,、,fos,转录因子（,AP-1,） 核内,sis,家族： 仅,sis,P28(,类,PDGF),胞外,myb,家族：,myb,、,myb-ets,核蛋白,(,转录因子,),核内,1. Based on family,（二）,the classfication of cellular oncogene,2,、,based on function and location,类 别 名 称 定 位 生物学功能,生长因子,c-sis,分泌到胞外 血小板源生长因子,生长因子受体,c-erb,B,细胞膜 表皮生长因子受体,c-fms,细胞膜 集落刺激因子,-1,受体,c-trk,细胞膜 神经生长因子受体,胞内传递蛋白,c-src,、,c-abl,细胞质 酪氨酸蛋白激酶,c-raf,、,c-mos,细胞质,Ser/Thr,蛋白激酶,c-ras,细胞膜,GTP/GDP,结合蛋白,转录调节因子,c-myc,细胞核内,DNA,结合蛋白,c-jun,、,c-fos,细胞核内 转录因子（,AP-1,）,c-erb,A,细胞核内 甾体激素受体类蛋白,四、,activation of oncogene,Activation factors,：,oncogene is,activated andabnormal expressed under some conditions such as virus infection, exposure to chemical carcinogenor ionizing radiation, leading to cell malignanttransformation and carcinogenesis.,Different cellular oncogenes under different condition can be activated by different pathway and become active oncogene,.,The results of oncogene activation will be,（,1,）,The expression productis abnormal or truncated,（,2,）,the products are normal but excessive,（,3,）,new products appear,Activation mechanism,：,Gene mutation,gene amplification, chromosomal rearrangements,variation of oncogene methylation gene overexpressionetc.,（一）,point,mutation,The proto-oncogenesare point mutated by exposure of,radiationand carcinogens, the amino acid or the structure of protein is changed and the protein is in continuous active state, which lead to carcinogenesis.,1982,MITUniversity,National CancerInstitute and Columbia University,：,human bladdercancer results from the point mutation of,c-H-ras,H-ras,normal cells G,G,C (12Gly),turmor cells G,T,C (12Val),the protein of mutated ras is locked in active state,GDP,GDP,GTP,GTP,Pi,Inactive Ras protein,The inputsignalstimulate GDP-GTP switch,Output signal,the protein of mutated ras is locked in active state,active Ras protein,GTPase activating protein,GAP,（,二）,Gene Amplication,Gene structure itself is normal,，,but because a part of chromosome is replicated excessively, the gene copies increase and the products overexpress.,Tumor occur,Breast cancer,erb,- B2,Small cell lung cancer,myc family,neuroblastoma, N-myc,The copies is related to progress,、,prognosis and metastasis,(1) When the amplified DNA is inserted into one of the chromosomes, it is termed homogeneous staining regions(HSR),(2) the amplified DNA are sometimes visible on a chromosome spread as a separate DNA fragments, referrred to as”double minutes(DM)”,Gene Amplification: Neuroblastoma,HSR,DM,（三）,chromosome gene translocation and rearrangements,chromosome gene translocation and rearrangements make some proto-oncogene to near to stong promoter or enhancer. Mostly,Found in,thebloodsystem tumors,The head of a gene is joined to the tail of another gene because of chromosome rearrangements and a new fusion protein produces. The fusion protein promotes cell transformation and induce carcinogenesis,Example:,Burkit lymphoma,，,c-myc in chromosome 8 move to chromosome 14, IgH , strong enhancer,Immunoglobulin gene,Chromosome 14,Chromosome 8,c-myc does not express,c-myc,基因,E,E,c-myc over expresses,translocation,Burkitt,s Lymphoma,Chronic Myelogenous Leukemia,Reciprocal translocation between long arms of 22 & 9,t(9;22), PHILADELPHIA CHROMOSOME (Ph1),MUTATION AND ACTIVATION OF oncogene,abl,to,bcr,= hybrid gene with tyrosine kinase activity,Chronic Myelogenous Leukemia,bcr-abl gene product,the Philadelphia (Ph) chromosome,Ideogram and banded chromosomes showing the normal chromosomes 9 and 22 plus the two derivating chromosomes resulting from the t(9;22)(q34;q11),The Ph chromosome was the first consistent abnormality noted in a human cancer,arising from a reciprocal translocation, t(9;22)(q34;q11.2), and molecularly by the fusion of the proto-oncogene,ABL, located on the long arm of chromosome 9, with the BCR gene of chromosome 22, known as,the breakpoint cluster region,(,bcr,).,DNA,甲基化状态的改变可导致基因结构和功能的异常，是细胞癌变过程中重要一步。,在真核细胞中最重要的甲基化碱基是,C,通常发生在双核苷酸区域（,CpG,岛）。,某些癌基因低甲基化和抑癌基因的高甲基化改变是细胞癌变的一个重要特征。,（四）,oncogenes methylation,甲基化的功能意义：抑制基因表达，维护染色体完整性，调节,DNA,重组。抵御外来入侵的寄生,DNA,。,低甲基化易致基因组中重复子同源重组，而导致基因组的不稳定性增加。,mutations at promoter controlling gene expression,基因表达是指基因的转录与翻释以及它们的调控。,基因表达水平的改变是细胞癌变的早期事件，过量表达与细胞的异常增生有关,Met,、,c-ErbB2,、,ras,（五）基因过量表达,(overexpression of oncogenes,),与人类肿瘤相关的特征性基因有三种，,H-ras,、,K-ras,和,N-ras,，分别定位于,11,、,12,、,1,号染色体，前二者是大鼠肉瘤病毒的转化基因，后者是从人神经母细胞瘤中分离得到,（一）,ras,基因家族,常见癌基因,共有特征,(1),基因组中均含,4,个编码的外显子和,1,个,5,端非编码外显子,.,(2),外显子所编码的蛋白为,188-189,个氨基酸残基，分子量为,21KD,即,P21,蛋白,，具有高度特异性和同源性，尤其在氨基酸序列的前,80,个氨基酸残基中，几乎无种属间差别，具有高度保守性。,Model of Action of,ras,Gene,(1)P21ras,位于细胞膜内侧，以软脂酸共价键形式固定于脂质双层膜的内表面,(2),对,GTP,和,GDP,具有高度亲和力，并有同源性,GTP,酶的活性,.,生化性质与,G,蛋白非常类似，提示,ras,蛋白可能也具有信号传导通路的作用，但目前尚未发现,ras,蛋白作用的特异受体和靶细胞,.,(,二,)myc,基因家族及其表达产物,c-myc,定位于第,8,号染色体的,8q24,区，其编码产物为,439,个氨基酸残基的蛋白质。,N-myc,定位于第,2,号染色体的,2p23-p24,区，其产物为,456,个氨基酸残基蛋白质。,L-myc,定位于第,1,号染色体的,1p32,区，编码产物为,364,个氨基酸残基的蛋白质。,蛋白产物定位于核内，为核转录调节因子，能够与特殊的,DNA,顺序结合,发生肿瘤时，,myc,基因家族成员可发生染色体基因易位、基因扩增以及表达过度。,Myc-activated mechanisms of action,（三）,erb,家族,表达产物：细胞骨架蛋白在细胞运动、分裂、信息传递、能量转换、代谢调控以及维持细胞形态方面具有重要作用。,人,erb-B,编码,的,蛋白与,EGF,受体相似，是,“,掐头,”,的,EGF,受体,，这个,“,截短,”,受体和其配体,-,表皮生长因子长期结合，从而可永远向细胞内传导促进生长的信号。,与野生型受体相比，跨膜区域无变化，但受体的两端变短，尤其是全部细胞外结构区域都被删除。,The ErbB signalling network,c-,erb,B-2/HER2/,neu,Molecular diagnosis of breast cancer. a,| Immunohistochemistry and,b,| fluorescence,in situ,hybridization (FISH) analysis of ErbB2 in human breast cancer. Immunohistochemistry was performed using HercepTest and FISH using a PathVysion ErbB2 DNA probe kit. The ErbB2 gene is seen as red fluorescence and the chromosome-17 centromeric,-satellite probe as green fluorescence.,（四）,c-Met,染色体,7q31,，编码,190KD,跨膜糖蛋白，,链（,50KD,）在胞外，,链（,145KD,）含胞外配体结合区、跨膜区、胞内酪氨酸激酶区。,蛋白表达位于腺样结构细胞的边缘。肝细胞因子（,HGF,）或离散因子（,SF,）作为,c-Met,受体的配体，形成,HGF/SF-c-Met,内分泌信号系统。,配体结合可使受体酪氨酸激酶磷酸化，促进细胞有丝分裂、细胞动力和向腺上皮的形态分化,扩增和过表达,肠型胃癌,基因重排：,1,号,chr,的易位启动子区,(tpr),与,c-Met gene 5,区融合形成,tpr-met gene,。在浅表性胃炎、萎缩性胃炎、肠化和胃癌组织中均存在,tpr-met mRNA,高表达。,（五）,Bcl-2,从,B,细胞淋巴瘤中鉴定出来，由染色体,t(14;18)(q32;q21),易位而激活，导致易位细胞中,Bcl-2,表达失控。,Proliferation: Malignancy,P53: Molecular,Policeman,Bcl-2,（六）,Mdm-2,位于,12q13-14,。进化保守基因，高表达时现癌基因功能,基因产物是,90kDa,的蛋白质，氨基酸序列分析发现具有一个核定位信号和两个锌指蛋白，提示是,一种,DNA,结合蛋白,，具有转录调节作用,.,Mdm-2,蛋白可与,p53&Rb,蛋白结合而使其功能失活,。基因产物可和,wtp53,和,mtp53,结合，起到对,p53,的负调节作用。,抑制,p53,介导的反式激活，阻止,p53,抑制细胞增殖和诱导细胞凋亡的功能，解除细胞,G1,期的阻滞并重新进入细胞周期。,mdm2,癌基因已在多种肿瘤中发现其突变与扩增，而且,mdm2,突变与,P53,突变不共存，,mdm2,扩增与肿瘤转移密切相关,（七）,细胞周期素（,Cyclins,）,/,细胞周期素依赖性激酶（,Cyclin-Dependant Kinases,，,CDK),第二节 抑癌基因,（,anti-oncogenes,，,tumor suppressor genes,）,抑癌基因的基本概念,抑癌基因作用机制,Rb,基因,“,控制细胞周期的重要基因,”,p53,基因,“,基因组卫士,”,一、抑癌基因的基本概念,概念：,是一类抑制细胞过度生长、增殖从而遏制肿瘤形成的基因。,它的丢失或失活与肿瘤的发生有关。,反之，其被导入或激活可抑制细胞的恶性表现。,发现：,1986,年，美国加州大学的,Geiser,等用,正常细胞与肿瘤细胞杂交实验,发现并提出抑癌基因,正常细胞与肿瘤细胞杂交实验,正常细胞,融合,非肿瘤型杂交细胞,（正常，但不稳定）,传代,肿瘤细胞,肿瘤细胞,11,号染色体某片段丢失,导入第,11,号染色体丢失片段,细胞转变为正常,抑癌基因的产物是抑制细胞增殖，促进细胞分化，和抑制细胞迁移，因此起负调控作用，通常认为抑癌基因的突变是隐性的。,判断抑癌基因的,3,个标准：,1,）正常组织中存在并表达,2,）恶性组织中突变而失活,3,）该基因的野生型导入该基因缺陷的恶性组织中能部分或全部抑制其恶性表型,review,常见的抑癌基因,基 因 定 位 相关肿瘤 作 用,跨膜受体类：,DCC,18q21,结直肠癌 编码表面糖蛋白（细胞粘附分子）,PTCH,9q22.3 HEDGEHOG,受体,胞质调节因子或结构蛋白：,APC,5p21,结直肠癌 可能编码,G,蛋白,NF,1 7q12.2,神经纤维瘤,GTP,酶激活剂,NF,2 22q,神经鞘膜瘤、脑膜瘤 连接膜与细胞骨架,转录因子和转录调节因子：,P53,17P,多种肿瘤 编码,P53,蛋白（转录因子）,Rb,13q14,视网膜母细胞瘤、骨 编码,P105Rb1,蛋白（转录因子）,肉瘤、肺癌、乳癌,DPC4,18q21.1,胰腺癌,TGF-,调节的,MAD,相关蛋白,MADR2,18q21,结直肠癌,TGF-,调节的,MAD,相关蛋白,VHL,3P,小细胞肺癌、宫颈瘤 转录调节蛋白,WT1,11P13,肾母细胞瘤 编码锌指蛋白（转录因子）,细胞周期因子：,P16,9p21,黑色素瘤 编码,P16,蛋白，,CDK 4, 6,抑制剂,P15,9p21,交质母细胞瘤 编码,P15,蛋白，,CDK 4, 6,抑制剂,P21,6q21,前列腺癌 编码,P21,蛋白，,CDK 2, 3, 4, 6,抑制剂,抑癌基因失活机制：,1.,抑癌基因纯合型缺失,2.,二个等位基因中的一个缺失,另一个等位基,因突变 （,LOH,）,化学致癌物、病毒等引起体细胞中的基因突变,3.,基因突变导致抑癌基因失活,4.,基因,5,端,CPG,岛胞嘧啶（,C-5,）高度甲基化，抑制抑,癌基因的转录,5.,癌蛋白的作用,Knudsons,两次打击论,mut,Me,mut,mut,Me,Me,Me,Me,Mutation,Methylation,First,hit,LOH Methylation,LOH Methylation,Second,hit,Second,hit,Mutation Mutation Methylation Bialielic,+ + + +,LOH methylation LOH methytaoon,抑癌基因在细胞信号传导的通路的多个层次发挥作用,跨膜受体：,PTCH,基因,DCC,基因,胞浆调节或结构蛋白：,NF1 PTEN APC NF2,等,转录因子或转录调节因子：,p53 WT1 RB1 VHL,等,细胞周期因子：,p16 p21 p15,等,DNA,损伤修复蛋白：,MSH2 MLH1 PMS2 ATM,BRCA1 BRCA2,等,二、抑癌基因作用机制,（一）,Rb,基因,“,控制细胞周期的重要基因”,视网膜母细胞瘤是由,Rb,基因失活所致。,基因结构：,200kb,，,27,外显子，,2.7kb mRNA,，编码,928,残基，分子量为,105kDa,的蛋白（,P105-Rb,）,P105-Rb,功能,：参与调节,E2F,等多种转录因子来控制细胞周期，影响细胞增殖和分化,P105-Rb,活性调节：,高磷酸化无活性型和非或低磷酸化活性型,，由,Cyclin-CDK,来调节；被多种病毒蛋白结合抑制,(,如：,SV40,大,T,抗原，腺病毒,E1A,蛋白，人乳头瘤病毒,E7,蛋白,),retinoblastoma,Pathogenesis of Retinoblastoma,Hit #1 (inherited),Hit #2,Familial,Hit #1,Hit #2,Sporadic,原发肿瘤：视网膜母细胞瘤（两个等位基因的缺失或失活）,相关肿瘤：骨肉瘤、小细胞肺癌、乳腺癌、膀胱癌,Cyclin A,cdk2,Cyclin D,cdk4,Cyclin E,cdk2,E2F,P,P,P,P,P,E2F,Rb,Rb,+,Ser780,Ser796,Thr373,Ser249/252,Ser870/811,G1 S,Restriction Point,DNA,Synthesis,RB1-0,结合,SV40T,E1A,HPV7,靶蛋白中包括一组,E2F,转录因子，它们所激活转录的靶基因其产物是,S,期所必须的。和,RB,结合后,E2F,的激活转录能力受到抑制，表明,RB,可以阻遏那些依赖,E2F,的基因表达,。通过这种途径,RB,可直接阻止细胞进入,S,期。,RB-E2F,的复合体也可直接阻遏某些靶基因。,E2F,从,RB,上解离以后这些基因才能表达。,不同程度磷酸化后，都可使,p105,活性缺乏或完全消失。非磷酸化的,Rb,可防止细胞增殖，当,DNA,肿瘤病毒抗原结合了非磷酸化的,Rb,时，,Rb,的活性就受到抑制，使细胞转化为无限增殖状态，形成肿瘤。,pRb,蛋白作用示意图,myc,myb,cdc2 DNA,聚合酶 胸苷激酶,二氢叶酸还原酶, pRb,CYCA,CDK2,RB,pathway and function,RB-E2F,1,、,p53,基因的发现,曾错误把,P53,基因定为癌基因,因当初从肿瘤细胞分离得到的,P53,基因如同,myc,基因一样，能和,ras,基因协同转化胚胎成纤维细胞，又依据癌基因为细胞显性表型的原则而被定癌基因，后发现实为其,突变型,。,1989,年，才确认为“抑癌基因”。,p53,基因与人类,50%,的肿瘤有关。,P53,基因突变型在血液系统肿瘤、膀胱癌、肝癌、肺癌、结肠癌以及口腔癌等的细胞中发现。,（二）,p53,基因,“,基因组卫士”,2,、,p53,的结构,基因：,20kb,，,11,外显子，,mRNA,：,2.5kb,，编码,393,氨基酸残基，分子量为,53kDa,的多肽链。,p53,蛋白中央核心区结合特定的,DNA,序列，,N,未端序列有转录活化的功能，,C,未端可使,p53,蛋白自身形成二聚体或四聚体。,3,、,p53,的功能,p53,是细胞内重要的转录因子，调节,p21,、,GADD45,、,BAX,等基因的转录表达来实现其功能。当射线或其它因素引起,DNA,损伤时，,p53,蛋白就被激活，执行如下功能：,调节细胞周期、促进,DNA,损伤修复：,如果细胞处于,G1,期,，,p53,蛋白通过,p21,蛋白抑制,cdk,活性，封闭细胞周期关卡,使细胞生长停止，并激活,GADD45,，加速,DNA,修复。,诱导细胞凋亡：,如果细胞已经处于,S,期,，,p53,蛋白促进相关细胞凋亡蛋白基因（,bax,等）表达，启动细胞凋亡。,P53,蛋白作用示意图,GADD45,P21,CDK2,4,6,BAX,等,生长停止,DNA,修复,细胞凋亡,p53 & Mdm2,p21,又是,p53,下游的转录激活产物，其上游调节区含有,p53,的结合位点，可抑制细胞周期素（,cyclin D,）,/,细胞周期素依赖性激酶（,CDK,）的底物磷酸化，导致,G1,期阻滞，使细胞在进入,S,期之前有充足的时间进行损伤,DNA,的修复。,Cyclin D-CDK4,复合体正常情况下可促进,Rb,蛋白磷酸化，低磷酸化或非磷酸化的,Rb,与,E2F,（通过,G1,限制点必需的转录因子）结合。,Rb,磷酸化可导致,E2F,的游离和释放，并使,E2F,转位至核，诱发多种基因的蛋白转录，进而促使细胞进入,S,期,.,4,、,p53,的功能特点,在复制和转录水平上抑制细胞增殖,P53,可被一些癌基因产物结合而失活,(,如：,SV40,大,T,抗原，腺病毒,E1B,蛋白，,HPV E6,蛋白,),P53,突变,具有显性失活的效应。,5,、,P53,突变与肿瘤,P,53,基因与人类,50%,的肿瘤有关，人类肿瘤中,P53,突变主要在高度保守区内，以,175,、,248,、,249,、,273,、,282,位点突变最高，不同种类肿瘤不同,The p53 family,p53 family members pathways,（三） 细胞周期因子,Cell cycle stage,cyclin-CDK complexes,inhibifors,p15,p16,p18,p21,p27,G1,cyclinD-CDK4/CDK6,G1 / S,cyclinE-CDK2,S,cyclinA-CDK2,G2 / M,cyclinB-CDK2,p21(cip1/wAF1),p27(Kip1),和,p15/p16,（,ink4,）合称为,Cki,蛋白，它们结合在,cdk-cyclin,二聚体上，使其失活。如在静止期通过这种途径阻止,RB,的磷酸化，使细胞周期不能进入,S,期。,主要几种,Cyclin-CDK,细胞周期复合物,P16,基因,P16,基因又叫,MTS(multiple tumor suppressor ),基因,，,是一种细胞周期中的基本基因，直接参予细胞周期的调控，负调节细胞增殖及分裂,一、,P16,基因结构及表达,P16,基因定位于人染色体,9p21,，,8.5Kb,由,2,个内含子及,3,外显子组成，第,1,外显子由,126bp,组成，第,2,外显子由,307bp,组成，第,3,外显子,bp,组成,.P16,基因是细胞周期中的一种基本基因,二、,P16,基因的表达产物及功能,P16,基因编码产物是,P16,蛋白，定位于细胞核内，为细胞周期素依赖激酶,CDK4,及,CDK6,抑制物，通过结合,CDK4,或,CDK6,而抑制,Cyclin D-CDK4/CDK6,复合物，阻止细胞分裂、增生，突变型,p16,蛋白无此抑制活性，细胞分裂失控，导致癌变。,三、,P16,基因与肿瘤,P16,基因已在多种肿瘤中发现缺失，突变,Kamb,等已经从肺癌、乳腺癌、皮肤癌、膀胱癌、肾癌、卵巢癌、淋巴瘤等中检测出,50%,以上,P16,纯合子缺失，在黑色素瘤中还检出无义错义，移码突变,.,表明,P16,参予各种组织的肿瘤形成,.,因此检测,P16,基因的突变与缺失，是判断肿瘤性质及预后的一项重要指标,.,（四）,DNA,损伤修复蛋白,BRCA1,：,基因全长,100kb,含,23,个外显子，,22,个内含子，,1,个单一长开放阅读框架，编码,1863,个氨基酸，,220KD,核内磷酸化蛋白，有锌指区，提示可调节基因表达。,肿 瘤： 家族性乳腺癌和卵巢癌,功 能：,DNA,结合区：转录调控,与,Rad51,相互作用，修复双链,DNA,断裂,BRCA2,：,13q21,编码,3418,个氨基酸 肿 瘤： 男女性乳腺癌，胰腺癌等,功 能： 有,DNA,结合区：转录调控,与,Rad51,相互作用，修复双链,DNA,断裂,BRCA1 and BRCA2,BRCA1 functions,Transcription factor: involved in the regulation of oestrogen receptor activity and related to the control of oestrogeninduced proliferation of breast tissue.,DNA repair: homologous recombination and repair of transcription-coupled oxidation-induced DNA damage.,Cell-cycle checkpoint control: interacts with RB, ESF1 and p53.,Chromatin remodelling.,BRCA1 domains,The RING-finger domain is a protein,protein-interaction domain, and binds BRCA1-associated RING domain 1 (BARD1). The carboxy-terminal BRCT domain is necessary for BRCA1,s function in DNA repair and transcriptional activation.,The highlighted mutations (denoted by *)are the two common founder mutations found in Ashkenazi Jews.,BRCA1 and BRCA2,BRCA2 functions,DNA repair: homologous recombination.,Cell-cycle checkpoint control: interacts with p53.,Chromatin remodelling.,BRCA2 domains,Exon 11 contains both the ovarian cancer cluster region (OCCR) and eight BRC repeats,which are required for binding to RAD51.Mutations in this region are associated with a greater risk of ovarian cancer and a lower risk of breast cancer than are mutations outside this region.,The highlighted mutations (denoted by *) are the common founder mutations found in Ashkenazi Jews and in Iceland.,Factors that modify risk of breast or ovarian cancer,NCOA3. Nuclear receptor coactivator 3 ( also known as amplified in breast cancer 1, AIB1),RAD51 is involved in the repair of doublestrand DNA breaks, and interacts with both BRCA1 and BRCA2.,TAMOXIFEN. One of a group of antioestrogenic drugs.Acts by blocking oestrogen signalling by binding to the oestrogen receptor.,HRAS,.,A non-coding polymorphism of the VNTR (variable number of tandem repeats) type is situated one kilobase downstream of the,HRAS,proto-oncogene on chromosome 11.,PTEN,/,MMAC1,/,TEP1,PTEN,( phosphate and tension homology deleted on chromosome 10,PTEN),又称为,MMACI(mutated in multiple advanted cancer1),和,TEPI(TGF-regulated and epithelial cell-enriched phosphatase),PTEN,：,10q23.3 9,个外显子 编码,403,个氨基酸,兼有酪氨酸磷酸酶,(PTP),和双重特异性磷酸酶,(DSP),结构模体,可以,使磷酸化的,Tyr,、,Ser,、,Thr,都去磷酸化，,抑制肿瘤发生、发展。,PI 3.4.5 P,3,PI - 4.5 P,2,PTEN,PTEN,与细胞骨架蛋白中的张力蛋白,(tensin),和辅助蛋白,(auxilin),具有同源性。对细胞迁移、铺展、聚焦粘附活动的抑制作用,等位基因缺失：,纯合性丢失：,胶质母细胞瘤，前列腺癌等有,15%,。,基因突变：,缺失突变，错义突变，无义突变，,mRNA,剪接突变，,突变一般在等位基因杂合性缺失基础上发生。,胶质母细胞瘤、子宫膜癌：,突变率可达,30-40%,。,前列腺细胞株：,突变,75100%,甲基化：,前列腺癌，晚期明显。,考登综合征,(cwden,病,CD,），,BZS(Bannayan-Zonana,或,Bannayan-Ruvalcabu),80%,存在,LOH,和基因突变。,转移抑制基因,(Metastasis Suppressor gene),肿瘤的转移与转移基因激活或转移抑制基因失活有关，是多种转移相关基因及转移抑制相关基因综合作用结果,.,Soble,认为凡是能抑制肿瘤转移形成的基因均可命名为转移抑制基因。,肿瘤转移抑制基因主要是抑制肿瘤细胞的转移表型,丝裂原活化蛋白激酶（,mitogen-activated protein kinase,，,MAPK,）。,MAPK,通路的基本组成是一种从酵母到人类都保守的三级激酶模式，包括,MAPK,激酶激酶（,MAP kinase kinase kinase,，,MKKK,）、,MAPK,激酶（,MAP kinase kinase,，,MKK,）和,MAPK,，这三种激酶能依次激活，共同调节着细胞的生长、分化、对环境的应激适应、炎症反应等多种重要的细胞生理,/,病理过程,nm23,基因,一、,nm23,基因及表达产物,人基因组中存在两个,nm23,基因，即,nm23-H1,，和,nm23-H2,，都定位于,17q21.3-22,，受两个独立的调控系统所调节。编码,152,个氨基酸组成的,17KD,蛋白，其中,nm23-H1,和,nm23-H2,的氨基酸序列同源性达,88%,nm23-H2,是,myc,的一个重要调节基因，,nm23,丧失有助于细胞永久生存,.,二、,nm23,功能,nm23-H1,蛋白是个转录因子。,nm23,蛋白改变,.,可使微管聚合异常而引起减数分裂时纺缍体的异常，导致癌细胞染色体非整倍体的形成，促进肿瘤的发展，还可能通过影响细胞骨架而引起细胞运动，参与浸润转移过程和发育过程,.,nm23,已在胃癌、骨肉瘤、膀胱癌、乳腺癌、肠癌等具有转移潜能的肿瘤细胞中呈低表达，在大肠癌中,nm23,在低表达与肿瘤状态和远距离转移紧密相关,nm23,编码的产物具有抑制肿瘤转移功能，,nm23,在分化良好的肿瘤中呈高水平表达，且,nm23,基因表达与淋巴结转移呈负相关，与无病生存期，整个生存期呈正相关，因此检测,nm23,基因的表达高低，可作为判断肿瘤有无转移的一个重要指标,.,三、,nm23,基因与肿瘤转移,癌基因与抑癌基因的特性比较,特,征,癌,基,因,抑,癌,基,因,突变等位基因的功能,获得功能，以显性方式起作用,丧失功能，以隐性方式起作用,致癌所需突变等位基因数,1,2,可通过生殖细胞遗传,现尚无例子,常有遗传的形式,体细胞突变的致癌作用,有,有,突变有组织的特异性,有一些，但能在许多组织中,遗传型常显示组织优先选择性起作用