ATM与癌症

共济失调毛细血管扩张症基因的突变（ataxia telangiectasis mutated gene,ATM）导致AT疾病（共济失调毛细血管扩张症）。AT患及其携带的患癌率较正常人明显增高，且易患淋巴样恶性肿瘤，其中主要包括淋巴瘤和白血病，说明ATM在其发病机理中起重要作用。ATM基因位于人类染色体11q22-23，其蛋白产物ATM是一种核蛋白，它的主要的功能区为P13K，位于羧基末端，与许多细胞周期检测点及DNA损伤反应蛋白具有同源性。ATM蛋白主要参与细胞周期关卡，DNA损伤修复和调亡等一系列重要的细胞功能的信号传导，并起到枢纽作用。AT患由于AT基因突变导致ATM蛋白结构和功能的变化，从而导致细胞周期关卡和DNA损伤后修复功能异常，表现为凋亡敏感性增加，细胞对放射线异常敏感。这些发现启示AT基因在癌症的基因治疗中有很大利用价值。     

DNA聚合酶基因在共济失调毛细血管扩张症家系突变状态的研究

目的通过对一个基因损伤修复缺陷性疾病共济失调毛细血管扩张症(AT)家系DNA聚合酶基因突变分析,初步观察其稳定突变位点,为上述疾病易感基因风险突变位点的进一步确定奠定基础。方法对该家系先征者DNA聚合酶基因家族,polA、polB、polD1、polD2、polE1、polG测序,检测突变位点,分析并筛选有意义突变位点;对该家系成员在先征者有意义突变区域直接测序。结果 AT家系患儿DNA聚合酶基因无外显子突变,但在polE1 12p24.3 132696619AG,该突变位置处于该基因的3′UTR下游;家系中患儿的母亲、外祖母及舅舅发生12p24.3 132696619AG。结论 AT家系先证者在DNA聚合酶基因外显子没有检测到突变位点,但在3′UTR位置检测到一个有意义突变位点,在家系成员中亦有突变,其可能为AT疾病的稳定突变位点。     

应用PCR-LDR法检测乙型肝炎病毒核苷类药物耐药多基因突变位点

目的用多重聚合酶连接反应-连接酶检测反应分型法（PCR-LDR）同时检测乙型肝炎病毒（HBV）的180、181、184、204、236、250位点突变。方法以50例慢性乙型肝炎患者血清中HBV的DNA为模板,获得PCR-LDR反应探针连接产物,用ABI 3130Sequencer进行检测分析。结果共检测出拉米夫定耐药突变8例（16%）、阿德福韦耐药突变5例（10%）,恩替卡韦耐药突变1例（2%）,拉米夫定和阿德福韦同时耐药突变1例（2%）,突变情况与直接测序法检测的结果完全一致。结论用PCR-LDR法可以快速检测HBV基因的已知位点突变,与直接测序等其他方法相比具有更简单、方便、快捷的优势,有利于临床医生早期发现乙肝病人的耐药情况并及时更改治疗方案。     

大肠癌相关基因突变与大肠癌遗传易感性的研究

正恶性肿瘤是一种体细胞遗传病,为相关基因结构与功能发生改变的结果,本文就大肠癌与之相关的基因突变及遗传易感性进行综述。1肿瘤的发生与基因突变的关系恶性肿瘤的发生及发展与相关的基因结构及其相关的功能发生改变有关。这些基因参与调控细胞的的正常生长周期、细胞的死亡及DNA的损伤修复。基因的种系突变(germ line mutation)在遗传性恶性肿瘤中起主要作用[1]。突变是生物进化的必要条件之一,没有突变就没有进化,就没有现代的遗     

Gadd45在恶性肿瘤中的研究进展

Gadd45与DNA损伤修复密切相关,全称为生长阻滞与DNA损伤诱生蛋白45（growth arrest anddNA damage inducible protein 45,Gadd45）,其基因家族属于p53和BRCA1的下游靶基因,在细胞生存及细胞凋亡中发挥重要作用。Gadd45家族由Gadd45α、Gadd45β和Gadd45γ三个成员组成,它们的基因排列序列非常相似,通常会在环境损伤因子作用下,随DNA修复过程的启动而诱导产生。     

基因atm与慢性淋巴细胞白血病

共济失调毛细血管扩张突变基因（atm）为肿瘤抑制基因，位于人类染色体的11q22-23，主要参与DNA损伤识别和修复，并在DNA双链断裂诱导的信号级联转导通路中起到枢纽作用。慢性淋巴细胞白血病（CLL）可出现高频率的atm基因杂合性缺失和核苷酸突变，并与其发病及侵袭性病程有关。本文将对atm基因的特点、作用机制及其在慢性淋巴细胞白血病中作用的研究进展作一综述。     

P53家族成员及相互作用与白血病关系的研究进展

P53基因具有诱导细胞凋亡、调控细胞周期、修复DNA损伤等重要功能,超过50％人类肿瘤及13％的血液系统恶性肿瘤中均存在P53基因的突变,P53基因异常与白血病的临床病程、预后转归等密切相关.与此同时,与P53结构具有高度同源性的P53家族成员P73、P63基因不仅具有与P53相似的诱导细胞凋亡、转录激活等活性,又可根据转录蛋白结构的多样性发挥不同的生物学作用,甚至拮抗P53基因的功能.研究发现,P73、P63基因同时具有抑癌和癌基因的双重特性,且在不同类型、不同阶段白血病中两者表现出不同表达活性及功能.本文就P53家族（P53、P73、P63）基因的结构、生物学功能异同点以及三者与白血病病程、预后转归、治疗等临床特点的关系作一综述.     

常州地区先天性甲减人群甲状腺素合成障碍相关致病基因的突变分析

目的探讨先天性甲减(CH)人群甲状腺素合成障碍相关致病基因的突变特点。方法提取89例CH患儿的外周血基因组DNA,通过靶向基因测序对5个已知甲状腺素合成障碍致病基因(DUOX2、TPO、TG、TPO和SLC5A5)的突变位点进行检测。结果共在54例CH患儿中检测出90个潜在致病突变,包括41个DUOX2突变,40个TG突变和9个TPO突变,TPO和SLC5A5基因未检测出。另有35例CH患儿未检出潜在致病突变,总体突变检出率为61%(54/89)。根据突变位点数目统计,有31例为单位点突变,23例为多位点突变;根据发生突变的基因数目统计,有43例为单基因发生突变,11例为多基因发生突变。结论常州地区甲状腺素合成障碍相关致病基因以DUOX2、TG为主,TPO突变相对较少,而TPO和SLC5A5较为罕见;多位点或多基因联合突变现象较为常见。     

JWA基因的研究进展

<正>JWA基因参与了细胞分化凋亡调控、氨基酸代谢、细胞骨架形成、DNA损伤与修复、氧化应激等多种功能的调控,研究显示JWA基因与恶性肿瘤发生、发展、预后等密切相关,近期还发现JWA基因还参与了肿瘤血管生成、耐药等,本文将对JWA基因作用及在恶性肿瘤中的研究现状进行综述。1 JWA基因和蛋白JWA基因是由周建伟教授1998年分离克隆的一个受维     

XRCC1基因多态性与胃癌易感性关系的研究进展

胃癌是消化道最常见的恶性肿瘤,胃癌发生发展与其他恶性肿瘤一样属多因素、多步骤、多阶段和多基因改变过程,研究显示许多基因在肿瘤的发生发展中起着关键性的作用,DNA作为一种遗传物质,承担着传递遗传信息的重要任务,必须保持相对的稳定性。然而DNA是一种相对比较活跃的物质,会发生自发性的损害,另外,DNA还必须承受来自内外环境的一些伤害,这些损伤打破了DNA的相对稳定性,就会导致一些突变的积聚,进而可能导致肿瘤的发生[1]。DNA修复系统通过逆转DNA损伤,在维持正常的细胞进程和基因的稳定性方面发挥着关键的作用,从而保证了生命系…     

Overexpression of the death-promoting gene bax-alpha which is downregulated in breast cancer restores sensitivity to different apoptotic stimuli and reduces tumor growth in SCID mice.

We have studied the expression of members of the bcl-2 family in human breast cancer. The expression pattern of these genes in breast cancer tissue samples was compared with the expression pattern in normal breast epithelium. No marked difference with regard to bcl-2 and bcl-xL expression was observed between normal breast epithelium and cancer tissue. In contrast, bax-alpha, a splice variant of bax, which promotes apoptosis, is expressed in high amounts in normal breast epithelium, whereas only weak or no expression could be detected in 39 out of 40 cancer tissue samples examined so far. Of interest, downregulation of bax-alpha was found in different histological subtypes. Furthermore, we transfected bax-alpha into breast cancer cell lines under the control of a tetracycline-dependent expression system. We were able to demonstrate for the first time that induction of bax expression in breast cancer cell lines restores sensitivity towards both serum starvation and APO-I/Fas-triggered apoptosis and significantly reduces tumor growth in SCID mice. Therefore, we propose that dysregulation of apoptosis might contribute to the pathogenesis of breast cancer at least in part due to an imbalance between members of the bcl-2 gene family.     

Prediction of hormone sensitivity by DNA microarray.

Endocrine-therapy continues to be extensively developed for treatment of breast cancer, and accurate therapeutic prediction of this hormone-associated cancer is strongly desired. Moreover, the role of estrogen and its receptor on the estrogen-dependent growth of breast cancer cells has not been clarified hitherto. Thus, to develop a new diagnostic tool for endocrine-therapy, and to address the molecular mechanism of estrogen-dependent breast carcinogenesis, we investigated the gene expression profile of estrogen-responsive genes in breast cancer using DNA microarray technique. We first comprehensively analyzed the profile of estrogen responsiveness among several estrogen receptor (ER)-positive cancer cell lines by a large-scale DNA microarray. Based on the obtained information, a total of 138 genes which showed high induction or repression of the expression by estrogen stimulation were selected and provided for custom microarray. The results of the custom microarray analysis were consistent with those of large-scale microarray analysis, and revealed that they were clearly categorized into early- or late-response types. Further analysis of these genes may provide new clues in the elucidation of the estrogen-dependent growth mechanisms of cancer. Furthermore, the custom microarray analysis of ER-positive breast cancer tissues also showed similar but not identical profiles to those of cell lines, indicating the potential of this custom microarray to predict the response to endocrine-therapy in the breast cancer. Moreover, in order to discover the new predictive factors for endocrine therapy in breast cancer patients, several candidate genes were selected and their expressions in breast cancer tissues were analyzed by real-time RT-PCR and by immunohistochemical technique. These studies could provide new clues for elucidation of the estrogen-dependent mechanisms of cancer and clinical benefit for patients.     

Antisense approaches in prostate cancer

Patients with hormone refractory prostate cancer have limited treatment options and new therapies are urgently needed. Advances in the understanding of the molecular mechanisms implicated in prostate cancer progression have identified many potential therapeutic gene targets that are involved in apoptosis, growth factors, cell signalling and the androgen receptor (AR). Antisense oligonucleotides are short sequences of synthetic modified DNA that are designed to be complimentary to a selected gene's mRNA and thereby specifically inhibit expression of that gene. The antisense approach continues to hold promise as a therapeutic modality to target genes involved in cancer progression, especially those in which the gene products are not amenable to small molecule inhibition or antibodies. The current status and future direction of a number of antisense oligonucleotides targeting several genes, including BCL-2, BCL-XL, clusterin, the inhibitors of apoptosis (IAP) family, MDM2, protein kinase C-alpha, c-raf, insulin-like growth factor binding proteins and the AR, that have potential clinical use in prostate cancer are reviewed.     

Hereditary breast cancer: beyond BRCA genetic analysis; PALB2 emerges

Abstract Despite the initial enthusiasm following the discovery of the association of BRCA germline mutations with hereditary breast and/or ovarian cancer, in many families affected by the syndrome no pathogenic mutations were detected in the two genes, although exhaustively searched. Many other genes have also been implicated due to their role in the same pathway of DNA repair where the BRCA1/2 genes are involved: homologous recombination (HR). Among them, PALB2 clearly emerges as the third breast cancer susceptibility gene. Its mutations have been detected in most populations investigated so far, albeit rarely: in 1%-4% of families negative for BRCA mutations, with either partial or complete penetrance. In some populations, PALB2 recurrent mutations have been identified and the estimated hazard risks are comparable to those of BRCA mutations. Since new effective targeted therapeutic options are becoming available ("synthetic lethality" with novel PARP inhibitors, etc.) that are applicable to all those patients with a defect in HR pathway, it is imperative to detect all these candidate patients. Data obtained from laboratory tests in the tumor (simple immunohistochemistry, gene expression analysis, etc.) can assist in the recognition of a specific pattern (BRCA1ness, HRless) so that even patients that look "sporadic" could benefit from these targeted therapies. Therefore, a genetic analysis algorithm is proposed, although with the advent of Next Generation Sequencing it is predicted that in the future most germline genetic alterations and also somatic or epigenetic events in the tumor of these genes will be detected.     

Replication and episomal maintenance of Epstein-Barr virus-based vectors in mouse embryonal fibroblasts enable synthetic lethality screens

Recently, we demonstrated the establishment of chemical and genetic synthetic lethality screens in cultured human cells. Here, we report the establishment of this method in mouse embryonal fibroblasts (MEF). The method employs an immortalized mammalian cell line, deficient in a gene of interest, which is complemented by an episomal survival plasmid expressing the wild-type cDNA for the gene of interest and the use of a novel green fluorescent protein (GFP)-based double-label fluorescence system. The crucial part in this endeavor has been the identification of a DNA replicon that could stably replicate in MEFs while under selection for survival and gets spontaneously lost relatively fast in the absence of such a pressure. Here, we show for the first time that EBV-based replicons but not polyoma virus-based ones can replicate and be stably maintained in MEFs. In the chemical screen, selective pressure imposed by synthetic lethal drugs prevented the spontaneous loss of the GFP-marked episome, enabling drug identification. Retention or spontaneous loss over time of the episomal survival plasmid could be sensitively detected in a large-scale blind test in the presence or absence of synthetic lethal chemicals, respectively. Establishing the synthetic lethality screen should thus permit high throughput screening for chemicals, which are synthetically lethal with any mouse mutant/knockout gene of interest. Moreover, it forms the basis for a genetic synthetic lethality screen in MEFs, an important new tool for mouse functional genomics.     

Polymer genomics: shifting the gene and drug delivery paradigms.

Pluronic, the A-B-A amphiphilic block copolymers of poly(ethylene oxide) and poly(propylene oxide), can up-regulate the expression of selected genes in cells and alter genetic responses to antineoplastic agents in cancer. Two key new findings are discussed in relation to current drug and gene delivery strategies. First, these block copolymers alone and in combination with a polycation, polyethyleneimine, can up-regulate the expression of reporter genes in stably transfected cells. This underscores the ability of selected synthetic polymers to enhance transgene expression through a mechanism that augments improved DNA delivery into a cell. Second, although, when used alone, Pluronic is "genetically benign," when combined with an antineoplastic agent, doxorubicin, it drastically alters pharmacogenomic responses to this agent and prevents the development of multidrug resistance in breast cancer cells. Collectively, these studies propose the need for a thorough assessment of pharmacogenomic effects of polymer therapeutics to maximize the clinical outcomes and understand the pharmacological and toxicological effects of polymer-based drugs and delivery systems.     

Predicting continuous values of prognostic markers in breast cancer from microarray gene expression profiles

The prognostic and treatment-predictive markers currently in use for breast cancer are commonly based on the protein levels of individual genes (e.g., steroid receptors) or aspects of the tumor phenotype, such as histological grade and percentage of cells in the DNA synthesis phase of the cell cycle. Microarrays have previously been used to classify binary classes in breast cancer such as estrogen receptor (ER)-alpha status. To test whether the properties and specific values of conventional prognostic markers are encoded within tumor gene expression profiles, we have analyzed 48 well-characterized primary tumors from lymph node-negative breast cancer patients using 6728-element cDNA microarrays. In the present study, we used artificial neural networks trained with tumor gene expression data to predict the ER protein values on a continuous scale. Furthermore, we determined a gene expression profile-directed threshold for ER protein level to redefine the cutoff between ER-positive and ER-negative classes that may be more biologically relevant. With a similar approach, we studied the prediction of other prognostic parameters such as percentage cells in the S phase of the cell cycle (SPF), histological grade, DNA ploidy status, and progesterone receptor status. Interestingly, there was a consistent reciprocal relationship in expression levels of the genes important for both ER and SPF prediction. This and similar studies may be used to increase our understanding of the biology underlying these markers as well as to improve the currently available prognostic markers for breast cancer.