细胞周期蛋白依赖性激酶2的功能及其抑制剂的研究

细胞周期蛋白依赖性激酶2(cyclin-dependent kinase 2,CDK2)是CDK家族中的重要成员之一。CDK2的表达或功能异常与多种疾病(如肿瘤、病毒复制与感染、免疫缺陷性疾病和雄性不育等)发生机制密切相关。CDK2抑制剂已成为抗肿瘤药物研发中的一个重要靶点。该文对CDK2在细胞周期调控、细胞增殖、细胞分化、细胞凋亡中的作用机制以及CDK2抑制剂的研发进行综述。     

共转染CDK1、CDK2siRNA对肿瘤细胞周期和细胞凋亡的影响

目的研究共转染CDK1、CDK2siRNA同时抑制CDKI、CDK2蛋白表达对肿瘤细胞周期和细胞凋亡的影响,探讨细胞周期主要调控分子在肿瘤细胞凋亡中的作用。方法以人宫颈癌细胞株HeLa细胞为研究对象,用脂质体lipofectamine2000同时转染CDKl和CDK2siRNA。在转染后48、60h收集细胞,用Western印迹检测CDKl、CDK2蛋白的表达,AnnexinV／PI检测转染细胞的凋亡,流式细胞术DNA含量检测分析细胞周期。转染细胞进行瑞氏一姬姆萨染色（Wright—Giemsa）后在显微镜下观察其形态变化i结果共转染CDKl、CDK2siRNA后48和60h,Western印迹结果显示CDKl和CDK2蛋白的表达都同时降低。共转染CDKl、CDK2siRNA后,细胞周期S期和G1／M期比例与对照相比有明显增加;共转染细胞经瑞氏一姬姆萨染色后在显微镜下可见双核或多核细胞增多;AnnexinV／PI检测结果显示共转染CDK1、CDK2siRNA的细胞在48和60h细胞凋亡率与对照相比有显著的升高。结论siRNA干扰导致的CDKI、CDK2表达同时降低不仅导致细胞周期s期和G1／M期的阻滞,也诱导了肿瘤细胞的凋亡。     

泛素-蛋白酶体降解途径在细胞周期调控中的作用

细胞周期的进程由一系列细胞周期蛋白依赖性激酶(CDK)和CDK活性调节因子驱动。泛素-蛋白酶体对细胞周期调节因子的降解是细胞调控分裂进程的重要手段。CDK活性抑制因子的降解是细胞分裂所必需的,而细胞周期正调控因子的降解则对维持细胞稳态至关重要。本从参与调控的2类泛素连接酶SCF复合物、APC／C复合物的结构和功能的角度阐述了泛素-蛋白酶体降解途径在整个细胞周期调控中的作用和意义。     

Cyclin D1与细胞周期调控

细胞周期是细胞生命活动中一个最重要的过程,其关键是G1 期的启动.细胞周期蛋白(Cyclin)、细胞周期蛋白依赖性激酶(CDKs)和CDK抑制因子(CKIs)是参与钿胞周期调控的主要因子.Cyclin D1是调控细胞周期G1期的关键蛋白,是一个比其他Cyclins更加敏感的指标,对细胞周期调控至关重要.综述Cyclin D1的结构和功能及其在肿瘤组织中的表达特征,初步分析Cyclin D在昆虫细胞周期调控的研究.     

CDK2在精母细胞和卵母细胞减数分裂中的作用

细胞周期蛋白依赖性蛋白激酶(Cyclin-dependent kinase,CDK)2是驱动细胞通过G1/S期检验点进入S期完成DNA合成的关键性调控蛋白.过去一度认为CDK2在减数分裂中的作用不像在有丝分裂中那么重要.直至2003年在敲除小鼠CDK2基因后出乎意料地发现小鼠生长发育正常,只是不育:生殖细胞减数分裂受到影响.这一发现引起人们重新审视CDK2在细胞增殖中的作用,对CDK2在减数分裂中的作用研究受到关注,本文就此作一综述.     

抑制PKCα对乳腺癌细胞特性及cyclin E和CDK2基因表达的影响

将构建的表达PKC_α反义RNA的质粒,转入人乳腺癌细胞Bcap-37中,通过筛选与检测获得PKC_α表达受到抑制的细胞。随后分析了细胞生长的血清依赖性、软琼脂成集落和致瘤性的变化,以及cyclin E和CDK2基因表达所受到的影响。结果显示PKC_α表达受到抑制后,乳腺癌细胞生长的血清依赖性增加,软琼脂成集落能力下降,细胞致瘤性被强烈抑制,说明PKC_α表达下降或活性降低伴随着乳腺肿瘤细胞恶性程度的减弱。同时,结果还表明PKC_α表达受到抑制后,导致细胞周期调控系统中的cyclin E及CDK2表达水平下降,说明PKC_α参与的信号转导系统与cyclin/CDK参与的细胞周期调控系统在功能上有着较为密切的联系。     

转录因子CREB对细胞周期调控机制的研究进展

细胞周期是一个复杂而精细的调节过程,有许多蛋白参与。其cyclin、CDK、CKI是细胞周期调控的内源性分子,三者在细胞周期中相互协调并与细胞信号转导通路之间形成复杂的调控网络。cAMP应答元件结合蛋白(cAMP response element binding protein,CREB)作为细胞核内调控因子,通过自身磷酸化实现调节功能,改变cyclin、CDK和CKI的转录,从而调控细胞周期。该文就近年来CREB对细胞周期调控的研究进展作一综述。     

乳杆菌DM9811发酵液提取物中RNA组分对人结肠癌细胞系HT-29增殖影响及分子机制研究

目的观察乳杆菌DM9811发酵液提取物中RNA组分对人结肠癌细胞系HT-29增殖的影响,探讨其对肠道肿瘤细胞的作用及其分子机制,为阐明乳杆菌与宿主相互作用规律的分子机制奠定基础。方法应用MTT方法研究不同时间不同浓度RNA组分对HT-29增殖的影响,应用流式细胞术、RT-PCR研究RNA组分对HT-29细胞周期的影响。结果乳杆菌DM9811发酵液中RNA组分能抑制HT-29细胞增殖,并呈现出时间-剂量依赖性;RNA组分作用于HT-29细胞24 h、48 h时,细胞周期G0/G1期所占比例明显上升,S期所占比例明显降低(P0.01),细胞周期调控因子CDK6、p27Kip1、p53的表达升高,CDK2、CDK4、PCNA的表达降低。结论乳杆菌DM9811代谢产物RNA在体外具有抑制癌细胞周期活性。     

本期重点推介

正Ras信号通路通过调控细胞周期蛋白E(CycE)和细胞周期蛋白依赖激酶2(CDK2)及上下游核内周期调节者来影响核内复制进程;而Myc作为细胞生长的转录调控因子,可调控CycD1,Cyclin-D2,CycE和CDK4等因子,促进细胞周期由G0/G1向S期过渡。为了明确果蝇体内Ras信号通路与Myc的关系以及对核内复制细胞的调控机理,华南师范大学     

肿瘤抑制基因Rb与细胞周期调控研究新进展

Rb与人类多种肿瘤发生关系密切,是一种重要的肿瘤抑制基因.Rb蛋白参与细胞周期调控,与p16、CDK4/6、cyclinD1等形成复杂的反馈调节网络,在G1/S关卡调控中处于中心环节,决定着细胞周期的进程.Rb又是核内信号与胞外信号相互作用的界面,受到胞内外多种因素的调控,使Rb功能与细胞生长、分化状态相适应.     

Involvement of cyclin-dependent kinase CDK1/CDC28 in regulation of cell cycle

Cyclin-dependent kinases (CDKs) are a family of enzymes essential for the progression of the cells through the cell cycle in eukaryotes. Moreover, genetic stability-maintaining processes, such as check-point control and DNA repair, require the phosphorylation of a wide variety of target substrates by CDK. In budding yeast Saccharomyces cerevisiae, the key role in the cell cycle progression is played by CDK1/CDC28 kinase. This enzyme is the most thoroughly investigated. In this review the involvement of CDC28 kinase in regulation of the cell cycle is discussed in the light of newly obtained data.     

酿酒酵母Cdk1抑制蛋白的研究进展

细胞周期蛋白依赖性激酶1(cyclin-dependent kinase 1,Cdk1)是真核生物细胞周期调控的核心,也是维持基因组稳定性的重要激酶,其活性受到严格调控.CDK抑制蛋白(cyclin-dependent kinase inhibitor,CKI)是调节其活性的一类关键负调控因子,CKI功能失活导致细胞不受控制地增殖,促进癌症的发生发展.酿酒酵母作为细胞周期研究的重要模式生物,在揭示CDK活性调控机制中发挥着重要作用.酿酒酵母中已发现的Cdk1抑制蛋白CKI包括Far1、Sic1以及最近鉴定的Cip1蛋白.这三个CKI蛋白在不同细胞时期中,通过抑制Cdk1活性调控细胞周期的进程.此外,CKI还在应对环境胁迫,保持基因组稳定性中发挥重要作用.本文对酿酒酵母Cdk1抑制蛋白CKI的研究进展,尤其是CKI在细胞周期运转及胁迫应答中的作用做出综述,以期为细胞周期及癌症的基础研究提供模式依据.     

Design,synthesis and biological evaluation of pyrimidine derivatives as novel CDK2 inhibitors that induce apoptosis and cell cycle arrest in breast cancer cells

Cyclin-dependent kinase 2 (CDK2) plays a key role in eukaryotic cell cycle progression which could facilitate the transition from G1 to S phase. The dysregulation of CDK2 is closely related to many cancers. CDK2 is utilized as one of the most studied kinase targets in oncology. In this article, 24 benzamide derivatives were designed, synthesized and investigated for the inhibition activity against CDK2. Our results revealed that the compound 25 is a potent CDK2 inhibitor exhibiting a broad spectrum anti-proliferative activity against several human breast cancer cells. Additionally, compound 25 could block cell cycle at G0 or G1 and induce significant apoptosis in MDA-MB-468 cells. These findings highlight a rationale for further development of CDK2 inhibitors to treat human breast cancer.     

CDK2-AP1改变与高频微卫星不稳定肠癌发生的关系

细胞周期素依赖激酶2-相关蛋白1（cyclin—dependent kinase 2-associated protein 1,CDK2-AP1）基因是一个重要的生长抑制基因,主要通过抑制细胞周期素依赖激酶2（cyclin—dependent kinase 2,CDK2）的活性发挥其生长抑制作用。新的研究发现,在结直肠癌患者中,CDK2-AP1的差异表达与微卫星状态相关,其表达缺陷是高频微卫星不稳定（microsatellite instability—high,MSI—H）结直肠癌（colorectal cancer,CRC）恶性转化的一个显著特点,并且参与疾病的发生发展。     

Inhibition of S/G2 phase CDK4 reduces mitotic fidelity

Cyclin-dependent kinase 4 (CDK4)/cyclin D has a key role in regulating progression through late G(1) into S phase of the cell cycle. CDK4-cyclin D complexes then persist through the latter phases of the cell cycle, although little is known about their potential roles. We have developed small molecule inhibitors that are highly selective for CDK4 and have used these to define a role for CDK4-cyclin D in G(2) phase. The addition of the CDK4 inhibitor or small interfering RNA knockdown of cyclin D3, the cyclin D partner, delayed progression through G(2) phase and mitosis. The G(2) phase delay was independent of ATM/ATR and p38 MAPK but associated with elevated Wee1. The mitotic delay was because of failure of chromosomes to migrate to the metaphase plate. However, cells eventually exited mitosis, with a resultant increase in cells with multiple or micronuclei. Inhibiting CDK4 delayed the expression of the chromosomal passenger proteins survivin and borealin, although this was unlikely to account for the mitotic phenotype. These data provide evidence for a novel function for CDK4-cyclin D3 activity in S and G(2) phase that is critical for G(2)/M progression and the fidelity of mitosis.     

Cyclin A2/cyclin-dependent kinase 1-dependent phosphorylation of Top2a is required for S phase entry during retinal development in zebrafish

Cyclin-dependent kinase 1 (CDK1) plays an essential role in cell cycle regulation.However,as mouse Cdk1embryos die early,the role of CDK1 in regulating the cell cycle and embryo development remains unclear.Here,we showed that zebrafish cdk1~(-/-)embryos exhibit severe microphthalmia accompanied by multiple defects in S phase entry,M phase progression,and cell differentiation but not in interkinetic nuclear migration.We identified Top2a as a potential downstream target and cyclin A2 and cyclin B1 as partners of Cdk1 in cell cycle regulation via an in silico analysis.While depletion of either cyclin A2 or Top2a led to the decreased S phase entry in zebrafish retinal cells,the depletion of cyclin B1 led to M phase arrest.Moreover,phosphorylation of Top2a at serine 1213 (S1213) was nearly abolished in both cdk1 and ccna2mutants,but not in ccnb1 mutants.Furthermore,overexpression of TOP2A~(S1213D),the phosphomimetic form of human TOP2A,rescued S phase entry and alleviated the microphthalmia defects in both cdk1~(-/-)and ccna2~(-/-)embryos.Taken together,our data suggest that Cdk1 interacts with cyclin A2 to regulate S phase entry partially through Top2a phosphorylation and interacts with cyclin B1 to regulate M phase progression.     

Upregulation of hsa_circ_0136666 contributes to breast cancer progression by sponging miR-1299 and targeting CDK6

Circular RNAs (circRNAs) can participate in multiple cancers, including breast cancer. Increasing circRNAs are recognized in various cancers because of the high-throughput sequencing. However, the potential physiological effect of hsa_circ_0136666 in breast cancer progression is unknown. In our study, the biological role of hsa_circ_0136666 in breast cancer development was studied. It was displayed that hsa_circ_0136666 was greatly increased in breast cancer. In addition, overexpression of hsa_circ_0136666 was able to promote Michigan Cancer Foundation-7 (MCF7) and BT474 cell proliferation and triggered cell cycle in G2/M phase. microRNA plays critical role in tumor development and they can act as direct targets of circRNAs. miR-1299 has been implicated as a famous tumor suppressor in many cancers. Here, miR-1299 was predicted as the target of hsa_circ_0136666. Meanwhile, its Upregulation repressed breast cancer proliferation, migration and invasion capacity, which could be reversed by the increase of hsa_circ_0136666. Furthermore, Cyclin-dependent kinase 6 (CDK6) was speculated as the downstream target of miR-1299. In MCF7 and BT474 cells, CDK6 was greatly overexpressed and it was shown that CDK6 contributed a lot to breast cancer progression. Subsequently, it was implied that hsa_circ_0136666 could modulate CDK6 levels positively in vitro. In conclusion, it was revealed that Upregulation of hsa_circ_0136666 promoted breast cancer progression by sponging miR-1299 and targeting CDK6.