CancerGenetics

1、Cancer Genetics罗建沅罗建沅二二0 0一四年十一月一四年十一月preventive double mastectomyCancer is a genetic diseaseCancersSporadically occurredHereditary occurredMutations of genesGenes mutation cause cancer encoding Proteins in signaling pathways for cell proliferation. Cytoskeletal components involved in contact inhibi

2、tion. Regulators of the mitotic cycle. Components of programmed cell death machinery. Proteins responsible for detecting and repairing mutations.Types of mutations Activating gain-of-function mutations of one allele of a proto-oncogene. Loss of function of both allele or dominant negative mutation o

3、f one allele of a tumor-suppressor gene. Chromosome translocation that cause misexpression of genes or create chimeric genes encoding proteins that have gained novel functional properties.Types of cancers Sarcomas: arisen in mesenchymal tissue: bone, muscle, or connective tissue; Carcinomas: origina

4、te in epithelial tissue: the calls lining the intestine, bronchi, or mammary ducts; Hematopoietic and lymphoid malignancies: leukemias and lymphomas, in bone marrow, lymphatic system, and peripheral blood.Further classified by Site, tissue type, histological appearance, degree of malignancy. Types o

5、f cancersLungBreast (women)ColonBladderProstate (men)Some common sarcomas:FatBoneMuscleLymphomas:Lymph nodesLeukemias:BloodstreamSome common carcinomas:肿瘤的几大生物学特征肿瘤的几大生物学特征u不受控生长，局部占位，损坏器官功能不受控生长，局部占位，损坏器官功能u 转移游走，多处占位，损坏多器官功能转移游走，多处占位，损坏多器官功能u 物理和化学效应，个体全面衰竭物理和化学效应，个体全面衰竭肿瘤研究内容肿瘤研究内容 病因学研究（环境致癌因素的筛

6、查） 遗传学研究（单基因遗传性肿瘤、多基因遗传性易感） 癌细胞的“还原性”研究（癌基因、癌蛋白的发现及功能研究） 新的诊断治疗方法的发明（化学、药物、靶向药、免疫、技术、设备、材料） 治疗效果的临床验证病因及机理病因及机理 80%是环境因素 遗传因素分为三个层面 单基因遗传 多基因易感，处于研究阶段 是唯一的体细胞基因突变的疾病 机体免疫状态与肿瘤发生有关What Causes Cancer?Some viruses or bacteriaHeredityDietHormonesRadiationSome chemicalsPopulation-Based StudiesCANADA:Leuk

7、emiaRegions of Highest IncidenceBRAZIL:CervicalcancerU.S.:ColoncancerAUSTRALIA:SkincancerCHINA:LivercancerU.K.:LungcancerJAPAN:StomachcancerHeredity? Behaviors? Other Factors?1005050Stomach Cancer(Number of new cases per 100,000 people)U.S.JapanJapanese familiesin U.S.1007070Colon Cancer(Number of n

8、ew cases per 100,000 people)U.S.JapanJapanese familiesin U.S.Three Patterns of Tumor Inheritance Heredity familial tumor syndrome (monogenic inheritance) Multigenic cancer genetic susceptibility (multigene involved) Somatic tumor cell gene rearrangement (acquired)Hereditary Familial Tumor Syndrome G

9、ermline gene defect Somatic cell, especially germ cells Vertical inheritance to descendents Mostly autosomal dominant inheritance Clinical characteristics (syndrome) More than 20 hereditary familial tumor gene clonedStudy strategy linkage analysis , positional cloning, whole genome sequencing Accoun

10、t for total tumor morbidity 1%Criteria of HFTS identification 1.Age of individual onset 2. Family aggregation 3. Clinical syndrome 4. Genes diagnosisExamples of HFTS involved Genes Transcriptional regulatory factor (regulate cell cycle) Rb、WTI、P53 DNA repair enzyme genes ERCC、FACC DNA ligase hmsH1、h

11、msH2 Cytoskeleton and cell adhesion genes APC、medlin综合征综合征 肿瘤肿瘤 相关特征相关特征/CA /CA 染色体定位染色体定位 克隆基因克隆基因 作用机理作用机理 家族性视网膜母细胞瘤 视网膜母细胞瘤骨肉瘤 发育迟缓 13q14 Rb Retinoblastoma调节细胞周期结合病毒癌基因转录调控E2F 家族性Wilms肿瘤 Wilms肿瘤 WAGRWilms肿瘤无虹膜泌尿生殖系统异常智力发育迟缓Deny-DrashBeckwith-Wiedemann综合征Organomegaly肾上腺皮质癌肝母细胞癌 11q13 11p15 WT1 锌指

12、转录因子调节细胞周期 多发性内分泌瘤2型（Sipple综合征） 髓样甲状腺癌 甲状旁腺增生前垂体腺瘤2型A 嗜铬细胞瘤 甲状旁腺增生2型B 嗜铬细胞瘤 粘膜神经瘤 Marfanoid habitus 家族性髓样甲状腺癌 10cen-10q11.2 Ret 受体酪氨酸激酶 着色性干皮病 皮肤癌 着色异常 性腺机能减退 CNS缺陷 8个互补群 ERCCXPA-XPG 螺旋酶核酸外切修复 Franconi贫血 AML 各种血细胞减少骨髓异常 4个互补群 FACC DNA修复 46BR 淋巴网状内皮增生症 阳光过敏免疫缺陷生长迟缓 DNA连接酶1 DNA连接 家族性肿瘤综合征家族性肿瘤综合征 译自译自

13、 Abeloff MD, et al. Clinical Oncology.New York : Curchill Livingsto,1995.168家族性肿瘤综合征家族性肿瘤综合征综合征综合征 肿瘤肿瘤 相关特征相关特征/CA /CA 染色体定位染色体定位 克隆基因克隆基因 作用机理作用机理 Bloom 综合征 实体瘤 毛细血管扩张免疫损伤 BloomDNA Helicase毛细血管扩张共济失调Ataxia Telangiectasia 淋巴瘤 小脑共济失调毛细血管扩张免疫缺陷 5个互补群11q22-q23 ATMDNA repair家族性腺瘤息肉病 结肠癌 结肠息肉先天性视网膜色素上皮肥

14、大Gardner综合征 5q21 APC 结合catenin HNPCC（Lynch综合征） 结肠癌结肠癌 HNPCC I型HNPCC II型子宫内膜癌（其他） 3p212p16 hMLH1hMSH2 DNA错配修复DNA错配修复 Li-Fraumeni综合征 肉瘤 乳腺癌肾上腺皮质癌脑瘤 17q p53 调节细胞周期及其他转录因子防UV损伤 神经纤维瘤病1型（NF1）（von-Reckling- hausen病） 神经纤维瘤 神经纤维肉瘤 Caf-au-lait斑 Lisch小结视神经胶质瘤 17q11.2 NF1 GAP相关的p21-ras调控与微管有关 神经纤维瘤病2型 听神经瘤 脑膜瘤

15、Schwann细胞瘤视神经胶质瘤 22q12 Merlin 连接细胞膜和细胞骨架 家族性乳腺癌 乳腺癌乳腺癌 卵巢癌 17q21.113q12-13 BRCAI BRCA2 转录因子 译自译自 Abeloff MD, et al. Clinical Oncology.New York : Curchill Livingsto,1995.168Genetic Susceptibility of Cancers (1) 1. Conception of susceptibility 2. Characteristics : a. Environmental dependent b. Multige

16、ne involved c. Genetic change is slight, both structurally and functionally (i.e. SNP) d. Slightly prone to familial aggregation、 high incident populationGenetic Susceptibility of Cancers (2)EnvironmentHeredityGenetic Susceptibility of Cancers (3)Features of Environmental Carcinogen1. Three types en

17、vironment carcinogen a chemical b physical c biological2. Common features a nonfatal injury b time、body site、way、duration、dose of exposure c strongly rely on individual susceptibility ( metabolism、compensation、repair、immunity)Genetic Susceptibility of Cancers (4) 1. SNP (Single Nucleotide Polymorphi

18、sm)point mutation2. Distribution frequency in human genome 1%, 1/1000bp 3. Some SNPs are related to disease susceptibility Sites of SNPs intron exon promoteraa changeno aa changeForms of SNPs influence on function Influence on responsible expression (response to special environment) Influence on sec

19、ondary structure alteration (protein binding , antigen presentation) Influence on gene activity (dominance recessive, gene dosage effect) Isogenetic combined effect (fatal) Influence on shearing (intron boundary) Genetic Susceptibility of Cancers (5) General Strategy of Study1. Has to be known gene2

20、. Candidate gene selection3. Scientific design of the experiment4. Main technologies : PCR-SSCP, DHPLC, sequencing et al 5. Functional relevance confirmation Genetic Susceptibility of Cancers (6) Category of candidate genesChemical metabolic enzymes systemDNA damage-repair systemImmunological recogn

21、ition-regulation-reaction systemBiological factors vs cellular interaction factorsApoptosis genes Genetic Susceptibility of Cancers (7) Procedures of defining Susceptible Gene1.Candidates selection2.SNP discovery and analysis3.Testing frequency of specific SNP in high-risk group4.Comparison of SNP f

22、requencies between disease group and control 5. Interaction analysis of SNPs, haplotype construction6. Functional testGenetic Susceptibility of Cancers (8) Significance of defining Susceptible Gene1. High-risk population identifying2. Intervention and prevention of cancers3. Early diagnosis and trea

23、tment4. Molecular mechanisms of carcinogenesis 5. Supplement to HGPGenetic variation of individualsWe are all 99.99% identical in our genomes BUTAdapted from Third Wave2012201420082010200620022007From $2B to $1K Human Genome 2,000,000 x dropDramatic Decrease of Cost in Sequencing a Human Genome!Fast

24、er & Cheaper NGSers $10/Gb one human genome/dayMiSeqHiSeq 2500NextSeqHiSeq X TenDecreasing Price Per GbIncreasing System Price & OutputFor ExamplesNGS SequencersRoche 454GS FLX TitaniumLife TechnologiesSOLiD 5500 xlPacific BiosciencesSMART PacBioRSIon TorrentIon Proton SequencerHelicos Biosc

25、iences HeliscopeMinIONIon Torrent PGMMiSeq DXHiSeq 2500HiSeq X TenOncogenes and Tumor Suppressor Genes in Tumor Cell Features of Oncogenes and Tumor Suppressor Genes Genes in charge of proliferation、 differentiation、apoptosisOncogene A mutant gene altered function or expression abnormal stimulation

26、of cell division and proliferation. The activating mutation can be: itself; regulatory elements; or genomic copy number unregulated function or overexpression of the oncogene. Dominant effect. OncogenesMutated/damaged oncogeneOncogenes accelerate cell growth and divisionCancer cellNormal cellNormal

27、genes regulate cell growthProto-Oncogenes and Normal Cell GrowthReceptorNormal Growth-Control PathwayDNACell proliferationCell nucleusTranscriptionfactorsSignaling enzymesGrowth factorOncogenes areMutant Forms of Proto-OncogenesCell proliferation driven by internal oncogene signalingTranscriptionAct

28、ivated gene regulatory proteinInactive intracellular signaling proteinSignaling protein from active oncogeneInactive growth factor receptorTumor Suppressor GenesNormal genes prevent cancerRemove or inactivate tumor suppressor genesMutated/inactivated tumor suppressor genesDamage to both genes leads

29、to cancerCancer cellNormal cellTumor Suppressor GenesAct Like a Brake PedalTumor Suppressor Gene ProteinsDNACell nucleusSignalingenzymesGrowth factorReceptorTranscriptionfactorsCell proliferationTumor suppressor Gate-keepers: directly involved in regulation of the cell cycle or growth inhibition. eg

30、, p53. Caretakers: involved in repairing DNA damage and maintaining genomic integrity, eg, WRN. The Structure of p531393IIIIIIIVVTransactivation DomainDNA Binding DomainTetramerization DomainNLSINLSII NLSIIINC* * DNA-Binding Regulatory RegionTumor suppression Transcriptional activator and repressor

31、Mutations in almost every kind of tumors Stress Response of p53StressDNA damagep53ActivateTargetsCell growth arrestApoptosisSenescenceActivation Phosphorylation AcetylationStabilizationMajor Post-translational Modification of p53Mdm2p531. Ubiquitination2. Phosphorylation3. Acetylationp53Pp53AATM/ATR

32、CBP/p300Mdm2DNA DamageMDM2APPhosphorylationAcetylationp53CBP/p300PCAFTFsTFsTFsp53p53PCAFTFsCBP/p300RNAPolymerase IIAAAAPPMDM2p53Growth ArrestCellular SenescenceApoptosisWRN is a member of RecQ familyWRN physically and functionally interacts with many proteinsWRN Telomere maintenanceTRF1TRF2POT1 DNA

33、replicationpol RPAPCNAFEN1TopoI DNA DSB repair HRNHEJp53MRNRad51Rad52BLMBRCA1Ku70/Ku80DNA- PKcsX4L4 DNA BERpol PPAR-1Werner syndrome Autosomal recessive disorders. Werners syndrome is named after Otto Werner, a German scientist, described the syndrome as part of his doctoral thesis in 1904.Werner sy

34、ndrome patients typically develop normally until they reach puberty. Following puberty they age rapidly, by age 40 they often appear several decades older. Numerous features of premature ageing: graying and loss of hair, wrinkling and ulceration of skin, atherosclerosis, osteoporosis, and cataracts.

35、 Short stature due to lack of usual growth spurt during puberty. Predisposition for cancerMostly associated with soft tissue sarcomas, osteosarcoma.Werner syndrome patientWilliam and Wilkens Publishing Inc.Chromosome translocation cause misexpression of genes or create chimeric genes encoding proteins that have gained novel functional properties. Philadelphia chromosome translocation, t(9;22)(q34;q11). Form BCR-ABL causes Chronic myelogenous leukemia (CML). Imatinib treat CML by inhibiting tyrosine kinase activity.Ph1 translocat