细胞色素P450 1A1基因多态性与我国某些肿瘤遗传易感性

近年来有关细胞色素P450基因多态性与肿瘤遗传易感性的研究正日益吸引越来越多的关注,本文对我国近年来有关细胞色素P450 1A1(CYP1Al)基因多态性与几种肿瘤遗传易感性的研究进行探讨,推测我国几种高发病率肿瘤的发生与我国CYP1A1基因多态分布状况有关,以此为进一步研究CYP1A1与肿瘤的关系作参考。     

MACC1与结肠癌的研究进展

MACC1(metastasis-associated in colon cancer1)是最近被报道的一种在结肠癌中调控肿瘤生长和转移的重要基因.MACCI作为诱导肿瘤转移发生的HGF/Met信号旁路的调控者,有可能作为肿瘤的早期阶段预测是否发生远处转移的一个生物学指标.MACC1可能成为结肠癌预后评估及进行个体化治疗方案制定的指标,可能成为肿瘤基因治疗的重要靶点.因此,研究MACCI与结肠癌的关系在对于肿瘤的防治有其重要的意义.本文结合国内外文献就MACCI在结肠癌发生发展及其转移过程的研究进展作一综述.     

CCNA1基因与肿瘤的相关性

细胞周期调节蛋白A1即细胞周期素A1（cyclinA1,CCNA1）在细胞周期调节中起关键作用,而细胞周期与肿瘤发生的关系是近年来肿瘤研究的热门课题之一。研究发现,CCNA1与恶性肿瘤的发生、生长、侵袭和转移等有着密切的关系,许多肿瘤的发生与CCNA1基因的启动子甲基化异常有直接或间接的关系,但在不同肿瘤中其发生机制并非相同。本文就CCNA1基因与肿瘤发生的相关性进行综述。     

抑癌基因OVCA1的研究进展

随着肿瘤分子生物学技术及学科的发展,人们认识到癌症是一种基因疾病,肿瘤的发生发展是多种基因参与的复杂过程,包括癌基因的异常激活和肿瘤抑制基因失活。新近分离鉴定的重要的肿瘤抑制基因——卵巢癌基因1(OVCA1)在多种肿瘤中存在高频率的缺失和突变,对多种癌细胞增殖有明显的抑制作用,可能作用于肿瘤发生的早期阶段,在哺乳动物中高度保守,提示在细胞中具有重要作用;OVCA1可能具有调控细胞周期、翻译、DNA损伤及胚胎发育等生物功能,具体作用机制尚不明确;体外研究显示,OVCA1的缺失表达导致肿瘤发生可能与周期蛋白D1上调表达、P16下调表达相关,与p53基因突变可能存在相互作用;OVCA1的缺失表达与卵巢癌发生发展及预后密切相关,与宫颈癌及人乳头瘤病毒感染、乳腺癌等恶性肿瘤的关系尚在研究中。我们简要综述了OVCA1基因的国内外研究进展,为卵巢癌等恶性肿瘤进行基因水平的诊治提供理论依据。     

抑癌基因D L C-1 的研究进展

DLC-1（frequently deletedin liver cancer）基因是新发现的一个肿瘤抑制基因。它的失活有可能参与肿瘤的发生和发展。本文拟就DLC-1基因的结构功能及其在遗传和表遗传方面的失活机制作一综述。     

CHL1基因在肿瘤中的研究进展

CHL1(close homologue of L1)基因是神经细胞粘附分子(cell adhesion molecule,CAM)L1基因家族中的一员,既往的研究认为,CHL1基因作为神经识别分子,主要参与调节神经前体细胞的增殖和神经元亚型的特异性分化。近期的研究发现,CHL1基因参与了对细胞生长和迁移的调节,影响了多种人类肿瘤的发生和发展过程。本文拟对CHL1基因在肿瘤中的最新研究进展进行综述。     

DLC-1基因与乳腺癌

肝癌缺失基因1（DLC-1）是一种肿瘤阻抑基因,位于人类染色体8p21.3-p22,在多种肿瘤中呈低表达或缺失,其与乳腺癌的发生、发展及侵袭转移关系密切。本文就DLC-1基因的结构及生物学功能、在乳腺癌中失活的机制和在乳腺癌中的表达及其意义作一综述。     

LEF-1表达与肿瘤进程研究进展

淋巴增强因子-1(lymphoid enhancer factor-1,LEF-1)属于高迁移组分(HMG)家族,它与TCRα的增强子相互作用形成特定的构象,从而与其它因子结合共同调节基因的表达。LEF-1作为核内的转录因子介导Wnt信号通路,对细胞的增殖、分化和凋亡起重要作用。近年来,研究显示许多肿瘤的发生与Wnt信号通路的异常有关,而LEF-1在肿瘤的发生发展侵润过程中起重要作用。同时,LEF-1是一个多启动子基因,编码产生致瘤的全长形式的LEF-1和对Wnt信号通路起负向调控作用的截短形式的LEF-1。研究结果表明,肿瘤的发生发展与LEF/TCF各亚型的比例有关。因此,研究LEF-1的结构、功能以及其在细胞增殖、细胞存活、肿瘤的发生发展过程中的作用意义重大。该文就LEF-1的表达以及与肿瘤的关系作一综述。     

SOCS-1基因与宫颈癌关系的研究新进展

SOCS-1基因定位在染色体16p13.3,编码的SOCS-1蛋白是细胞因子信号转导抑制因子(SOCS)家族的成员之一,最初研究认为SOCS-1主要通过对JAK/STAT信号通路的负性调节从而对多种细胞因子、激素的进行调节,近来有研究表明SOCS-1同样能下调TLR信号通路的活性.细胞因子及TLR信号通路在细胞的生长、成熟、分化及机体的免疫调节中发挥了重要的作用.在多种恶性肿瘤中研究显示SOCS-1呈现基因广泛甲基化及蛋白表达缺失,致JAK/STAT通路的持续活化,与肿瘤的发生发展有关,提示SOCS-1的作用类似于抑癌基因,而在一些肿瘤中则见SOCS-1的高表达,SOCS-1在肿瘤中的作用机制仍存在争议.近年来SOCS-1在宫颈癌中的作用得到重视,但其作用机制尚未明确.而HPV感染可能促进了SOCS-1基因的异常表达,SOCS-1的沉默在宫颈癌的发生发展中可能发挥了重要作用.     

新的肿瘤抑制基因-ARLTS1

小分子GTP蛋白涉及肿瘤发生中多条信号通路的改变。类核糖基化因子肿瘤抑制基因1（ADP-ribosylation factor-like tumor suppressorgene1,ARLTS1）,是小分子GTP蛋白Ras超家族中ARF家族的成员之一。该基因是低显性基因,可因启动子超甲基化而失调。有两种ARLTSl的多态性与肿瘤的家族风险相关。ARLTS1表达下调与部分肿瘤发生有重要关系,而恢复其表达则会诱导caspase依赖的细胞凋亡发生,并减少肿瘤的体内生长。通过基因微阵列实验发现,转导ARLTS1基因诱导细胞凋亡过程中众多涉及细胞存活、增殖和发育的信号通路。     

DEC1 and MIC-1

Comment on: Qian Y, et al. Proc Natl Acad Sci USA 2012; 109:11300-5.     

LINE-1编码蛋白L1-ORF1的原核表达纯化和多克隆抗体制备

目的: 制备具有肿瘤组织特异性表达的L1-ORF1蛋白多克隆抗体并进行初步应用研究。方法:采取基因工程表达方法制备L1-ORF1蛋白,免疫家兔制备多克隆抗体,间接ELISA检测抗体效价,Western blot和细胞免疫荧光方法检测抗体特异性,免疫检测验证其识别肿瘤细胞内L1-ORF1蛋白的特异性。结果:制备的抗L1-ORF1蛋白多克隆抗体具有很高的敏感性与特异性,免疫学检测表明该抗体不仅能检测出正常细胞中瞬时表达的L1-ORF1蛋白,而且可检测出肿瘤细胞中天然表达的L1-ORF1蛋白。结论:制备的多克隆抗体具有较高的敏感性与特异性,为以后该抗体的进一步应用奠定了基础。     

Role of the ASK1-SEK1-JNK1-HIPK1 signal in Daxx trafficking and ASK1 oligomerization

Overexpression of JNK binding domain inhibited glucose deprivation-induced JNK1 activation, relocalization of Daxx from the nucleus to the cytoplasm, and apoptosis signal-regulating kinase 1 (ASK1) oligomerization in human prostate adenocarcinoma DU-145 cells. However, SB203580, a p38 inhibitor, did not prevent relocalization of Daxx and oligomerization of ASK1 during glucose deprivation. Studies from in vivo labeling and immune complex kinase assay demonstrated that phosphorylation of Daxx occurred during glucose deprivation, and its phosphorylation was mediated through the ASK1-SEK1-JNK1-HIPK1 signal transduction pathway. Data from immunofluorescence staining and protein interaction assay suggest that phosphorylated Daxx may be translocated to the cytoplasm, bind to ASK1, and subsequently lead to ASK1 oligomerization. Mutation of Daxx Ser667 to Ala results in suppression of Daxx relocalization during glucose deprivation, suggesting that Ser667 residue plays an important role in the relocalization of Daxx. Unlike wild-type Daxx, a Daxx deletion mutant (amino acids 501-625) mainly localized to the cytoplasm, where it associated with ASK1, activated JNK1, and induced ASK1 oligomerization without glucose deprivation. Taken together, these results show that glucose deprivation activates the ASK1-SEK1-JNK1-HIPK1 pathway, and the activated HIPK1 is probably involved in the relocalization of Daxx from the nucleus to the cytoplasm. The relocalized Daxx may play an important role in glucose deprivation-induced ASK1 oligomerization.     

Antagonism between Cry1Ac1 and Cyt1A1 toxins of bacillus thuringiensis

Most strains of the insecticidal bacterium Bacillus thuringiensis have a combination of different protoxins in their parasporal crystals. Some of the combinations clearly interact synergistically, like the toxins present in B. thuringiensis subsp. israelensis. In this paper we describe a novel joint activity of toxins from different strains of B. thuringiensis. In vitro bioassays in which we used pure, trypsin-activated Cry1Ac1 proteins from B. thuringiensis subsp. kurstaki, Cyt1A1 from B. thuringiensis subsp. israelensis, and Trichoplusia ni BTI-Tn5B1-4 cells revealed contrasting susceptibility characteristics. The 50% lethal concentrations (LC50s) were estimated to be 4,967 of Cry1Ac1 per ml of medium and 11.69 ng of Cyt1A1 per ml of medium. When mixtures of these toxins in different proportions were assayed, eight different LC50s were obtained. All of these LC50s were significantly higher than the expected LC50s of the mixtures. In addition, a series of bioassays were performed with late first-instar larvae of the cabbage looper and pure Cry1Ac1 and Cyt1A1 crystals, as well as two different combinations of the two toxins. The estimated mean LC50 of Cry1Ac1 was 2.46 ng/cm2 of diet, while Cyt1A1 crystals exhibited no toxicity, even at very high concentrations. The estimated mean LC50s of Cry1Ac1 crystals were 15.69 and 19.05 ng per cm2 of diet when these crystals were mixed with 100 and 1,000 ng of Cyt1A1 crystals per cm2 of diet, respectively. These results indicate that there is clear antagonism between the two toxins both in vitro and in vivo. Other joint-action analyses corroborated these results. Although this is the second report of antagonism between B. thuringiensis toxins, our evidence is the first evidence of antagonism between toxins from different subspecies of B. thuringiensis (B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. israelensis) detected both in vivo and in vitro. Some possible explanations for this relationship are discussed.     

Regulation of PCTAIRE1 protein stability by AKT1, LKB1 and BRCA1

PCTAIRE1, also known as CDK16, is a cyclin-dependent kinase that is regulated by cyclin Y. It is a member of the serine-threonine family of kinases and its functions have primarily been implicated in cellular processes like vesicular transport, neuronal growth and development, myogenesis, spermatogenesis and cell proliferation. However, as extensive studies on PCTAIRE1 have not yet been conducted, the signaling pathways for this kinase involved in governing many cellular processes are yet to be elucidated in detail. Here, we report the association of PCTAIRE1 with important cellular proteins involved in major cell signaling pathways, especially cell proliferation. In particular, here we show that PCTAIRE1 interacts with AKT1, a key player of the PI3K signaling pathway that is responsible for promoting cell survival and proliferation. Our studies show that PCTAIRE1 is a substrate of AKT1 that gets stabilized by it. Further, we show that PCTAIRE1 also interacts with and is degraded by LKB1, a kinase that is known to suppress cellular proliferation and also regulate cellular energy metabolism. Moreover, our results show that PCTAIRE1 is also degraded by BRCA1, a well-known tumor suppressor. Together, our studies highlight the regulation of PCTAIRE1 by key players of the major cell signaling pathways involved in regulating cell proliferation, and therefore, provide crucial links that could be explored further to elucidate the mechanistic role of PCTAIRE1 in cell proliferation and tumorigenesis.     

Antagonism between Cry1Ac1 and Cyt1A1 Toxins of Bacillus thuringiensis

Most strains of the insecticidal bacterium Bacillus thuringiensis have a combination of different protoxins in their parasporal crystals. Some of the combinations clearly interact synergistically, like the toxins present in B. thuringiensis subsp. israelensis. In this paper we describe a novel joint activity of toxins from different strains of B. thuringiensis. In vitro bioassays in which we used pure, trypsin-activated Cry1Ac1 proteins from B. thuringiensis subsp. kurstaki, Cyt1A1 from B. thuringiensis subsp. israelensis, and Trichoplusia ni BTI-Tn5B1-4 cells revealed contrasting susceptibility characteristics. The 50% lethal concentrations (LC₅₀s) were estimated to be 4,967 of Cry1Ac1 per ml of medium and 11.69 ng of Cyt1A1 per ml of medium. When mixtures of these toxins in different proportions were assayed, eight different LC₅₀s were obtained. All of these LC₅₀s were significantly higher than the expected LC₅₀s of the mixtures. In addition, a series of bioassays were performed with late first-instar larvae of the cabbage looper and pure Cry1Ac1 and Cyt1A1 crystals, as well as two different combinations of the two toxins. The estimated mean LC₅₀ of Cry1Ac1 was 2.46 ng/cm² of diet, while Cyt1A1 crystals exhibited no toxicity, even at very high concentrations. The estimated mean LC₅₀s of Cry1Ac1 crystals were 15.69 and 19.05 ng per cm² of diet when these crystals were mixed with 100 and 1,000 ng of Cyt1A1 crystals per cm² of diet, respectively. These results indicate that there is clear antagonism between the two toxins both in vitro and in vivo. Other joint-action analyses corroborated these results. Although this is the second report of antagonism between B. thuringiensis toxins, our evidence is the first evidence of antagonism between toxins from different subspecies of B. thuringiensis (B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. israelensis) detected both in vivo and in vitro. Some possible explanations for this relationship are discussed.     

Dial 9-1-1 for DNA damage: the Rad9-Hus1-Rad1 (9-1-1) clamp complex

Genotoxic stress activates checkpoint signaling pathways that block cell cycle progression, trigger apoptosis, and regulate DNA repair. Studies in yeast and humans have shown that Rad9, Hus1, Rad1, and Rad17 play key roles in checkpoint activation. Three of these proteins-Rad9, Hus1, and Rad1-interact in a heterotrimeric complex (dubbed the 9-1-1 complex), which resembles a PCNA-like sliding clamp, whereas Rad17 is part of a clamp-loading complex that is related to the PCNA clamp loader, replication factor-C (RFC). In response to genotoxic damage, the 9-1-1 complex is loaded around DNA by the Rad17-containing clamp loader. The DNA-bound 9-1-1 complex then facilitates ATR-mediated phosphorylation and activation of Chk1, a protein kinase that regulates S-phase progression, G2/M arrest, and replication fork stabilization. In addition to its role in checkpoint activation, accumulating evidence suggests that the 9-1-1 complex also participates in DNA repair. Taken together, these findings suggest that the 9-1-1 clamp is a multifunctional complex that is loaded onto DNA at sites of damage, where it coordinates checkpoint activation and DNA repair.