Plkl与p21~（WAF1/CIP1）在肝细胞癌中的表达

目的细胞周期抑制因子p21WAF1/CIP1（p21）可在转录水平抑制Polo-like kinase1（Plk1）基因的表达,本文旨在探讨Plk1和p21蛋白在肝细胞癌中的表达及相关性。方法应用Western Blot方法检测10对原发性肝细胞癌和癌旁组织中Plk1和p21蛋白的表达情况。通过将pFlex-p21表达质粒瞬时转染人肝癌细胞系HepG2细胞,进一步检测p21过表达对Plk1mRNA和蛋白表达的影响。结果 Plk1在10例肝癌组织中的表达均高于配对癌旁组织,p21蛋白在7对肝癌组织中的表达高于配对癌旁组织。HepG2细胞瞬时表达p21质粒后,Plk1的蛋白表达和mRNA水平均无变化（P〉0.05）。结论 Plk1和p21在肝细胞癌组织中的表达具有一定的肿瘤特异性。肝癌组织中p21蛋白过表达可能不具有抑制Plk1表达的作用,具体机制还有待于进一步研究。     

非霍奇金淋巴瘤p27Kip1、p21WAF1及cyclin E表达的意义

目的 :探讨在非霍奇金淋巴瘤 (NHL)中 p2 7Kip1及其同族抑癌基因 p2 1WAF1、细胞周期素E(cyclinE)的表达意义。 方法 :应用免疫组化S P法检测 40例NHL患者受累淋巴结中 p2 7Kip1、p2 1WAF1、cyclinE蛋白表达情况 ,同时结合临床病理资料进行分析。结果 :40例NHL中 ,p2 7、p2 1、cyclinE蛋白阳性表达分别为 2 0例 (72 5 % )、8例 (2 0 % )、2 6例 (6 5 % )。 3种蛋白在NHL中的阳性表达与患者的性别、年龄及免疫分型无明显相关性 (P >0 0 5 ) ,但均与组织分化程度明显相关 (P <0 0 5 )。p2 7与cy clinE的表达水平间存在显著负相关 (r =- 0 2 7,P <0 0 1)。结论 :NHL患者淋巴组织中存在较高比例的 p2 7、p2 1蛋白阴性表达及较高比例的cyclinE阳性表达 ,说明在NHL的发生发展过程中 ,p2 7及其相关因素cyclinE ,同族基因 p2 1蛋白水平的异常变化起着重要作用 ,可作为NHL诊断标记物及预后指标。     

TIGAR induces p53-mediated cell-cycle arrest by regulation of RB-E2F1 complex

Background:

p53 induces cell-cycle arrest and apoptosis in cancer cells and negatively regulates glycolysis via TIGAR. Glycolysis is crucial for cancer progression although TIGAR provides protection from reactive oxygen species and apoptosis. The relation between TIGAR-mediated inhibition of glycolysis and p53 tumour-suppressor activity is unknown.

Methods:

RT–PCR, western blot, luciferase and chromatin immunoprecipitation assays were used to study TIGAR gene regulation. Co-IPP was used to determine the role of TIGAR protein in regulating the protein–protein interaction between retinoblastoma (RB) and E2F1. MCF-7 tumour xenografts were utilised to study the role of TIGAR in tumour regression.

Results:

Our study shows that TIGAR promotes p21-independent, p53-mediated G1-phase arrest in cancer cells. p53 activates the TIGAR promoter only in cells exposed to repairable doses of stress. TIGAR regulates the expression of genes involved in cell-cycle progression; suppresses synthesis of CDK-2, CDK-4, CDK-6, Cyclin D, Cyclin E and promotes de-phosphorylation of RB protein. RB de-phosphorylation stabilises the complex between RB and E2F1 thus inhibiting the entry of cell cycle from G1 phase to S phase.

Conclusion:

TIGAR mediates de-phosphorylation of RB and stabilisation of RB–E2F1 complex thus delaying the entry of cells in S phase of the cell cycle. Thus, TIGAR inhibits proliferation of cancer cells and increases drug-mediated tumour regression by promoting p53-mediated cell-cycle arrest.     

Cyclin D1在乳腺浸润性小叶癌的表达及其意义

  目的  探讨Cyclin D1在乳腺浸润性小叶癌中的表达及其意义。  方法  采用免疫组化染色方法对75例具有经典型乳腺浸润性小叶癌结构的标本进行Cyclin D1免疫组化检测。  结果  Cyclin D1阳性表达率为93.33%(70/75), 其中41例(54.67%)呈弥漫强阳性表达(3+, 6~7分), 21例(28%)呈中阳性表达(2+, 4~5分), 8例(10.67%)呈弱阳性表达(1+, 2~3分); 仅有5例(6.67%)呈阴性表达(0~1分)。Cyclin D1的阳性表达在患者年龄是否≥ 50岁、肿瘤最大径是否≥ 2 cm、淋巴结是否有转移、是否累及乳头间质及其下大导管、雌孕激素受体有无及P53是否突变等因素的分组中无统计学差异(P > 0.05);而Cyclin D1阳性表达程度与淋巴结是否有转移具有一定的负相关性(P < 0.05)。  结论  Cyclin D1在乳腺浸润性小叶癌中呈过表达状态, 该蛋白过表达提示其在基因水平上可能出现了某种程度的异常, 这一假设尚需进一步行基因检测加以证实。     

Cyclins非时相性表达和MDR1与胃肠道恶性肿瘤分期的研究

目的：研究胃肠道恶性肿瘤的4种主要Cyclins的表达规律,以此为依据对恶性肿瘤进行分型,并结合肿瘤标本中MDR1（多药耐药基因）的表达情况,与肿瘤TNM分期进行相关性研究。方法：使用流式细胞术分析新鲜手术获取的肿瘤标本的CyclinD1,E,A,B1及与MDR1表达情况,再记录术后病理报告进行TNM分期。结果：根据4种主要Cyclins的表达情况对恶性消化道肿瘤分为Ⅰ～Ⅳ型cyclin非时相性表达类型,此Ⅰ～Ⅳ型细胞周期类型与TNM分期有一致性（Kappa值为0．599,P〈0．01）,Ⅰ～Ⅳ型细胞周期类型中MDR1的表达水平逐渐增高（Spearman相关系数0．495,P〈0．01）。结论：根据4种主要Cyclins（Cyclin D1,E,A,B1）的表达情况对胃肠肿瘤进行的分型具有与TNM分期相同的意义,可以说是对“分子分期”的一种探索。在消化道肿瘤中,MDR1与肿瘤细胞周期破坏类型有关,对治疗具有指导意义。     

细胞周期蛋白D1基因表达在心肌肥大形成中的时相性变化

目的：观察心肌肥大形成过程中细胞周期蛋白Ｄ１（ｃｙｃｌｉｎ Ｄ１）基因表达的时相性变化,并探讨ｃｙｃｌｉｎ Ｄ１在心肌肥大形成中的作用。方法：肛用腹主动脉缩窄法建立大鼠心肌肥大模型,设缩窄手术组及假手术对照组,观察两组大鼠手术后不同时间心脏左心室（含左心室游离与室间隔）质量与体质量比、左心室游离壁厚度及心肌细胞横径的变化,以确证模型的稳定建立;其后应用ＲＮＡ印迹法分析检测ｃｙｃｌｉｎ Ｄ１基因表达     

17alpha-estradiol inhibits LAPC-4 prostatic tumor cell proliferation in cell cultures and tumor growth in xenograft animals

BACKGROUND: Blockade of androgen activity is a major effective therapy for advanced prostate cancer. Estrogen analogs have been used for prostate cancer therapy for years presumably by inhibiting testosterone biosyntheses, but with considerable adverse events due to their classic estrogenic activity. With the discovery of the estrogen receptor (ER) beta and its presence in prostate tumor cells, evaluation of estrogen analogs with less classic estrogenic activity in prostate cancer therapy is emerging. METHODS: The effects of 17alpha-estradiol (alphaE2), a stereo-isomer of 17beta-estradiol (betaE2), on dihydrotestosterone (DHT)-induced cell growth and gene expressions were examined in androgen-dependent LAPC-4 prostatic tumor cells and in LAPC-4 xenograft animals, and compared to those of betaE2. RESULTS: Both alphaE2 and betaE2 attenuated DHT induction of PSA gene expression, cell proliferation, and cell growth in cultured LAPC-4 cells. The inhibition of cell proliferation was associated with a blockade of DHT-induced cyclin A and cyclin D1 expression by alphaE2 and betaE2. In LAPC-4 xenograft mice, alphaE2 significantly inhibited tumor growth without altering the plasma testosterone level, while betaE2 failed to inhibit tumor growth even though it significantly inhibited PSA gene expression. CONCLUSION: alphaE2 is an effective agent for inhibition of DHT-induced PSA, cyclin A, cyclin D1 gene expression, and cell proliferation in LAPC-4 cells, and tumor growth in LAPC-4 xenograft mice.     

A putative role for cell cycle-related proteins in microtubule-based neuroplasticity

Cyclins and cyclin-dependent kinases (Cdks) are the main components that control the orderly progression through cell cycle. In the mature nervous system, terminally differentiated neurons are permanently withdrawn from cell cycle, as mitotic quiescence is essential for the functional stability of the complexly wired neuronal system. Recently, we characterized the expression and colocalization of cyclins and Cdks in terminally differentiated pyramidal neurons. The functional impact of the expression of cell cycle-related proteins in differentiated neurons, however, has not been elucidated yet. In the present study, we show by immunoelectron microscopy and immunobiochemical methods an association of cyclins and Cdks with the microtubule network. Cyclins D, E, A and B as well as Cdks 1, 2 and 4 were also found to be associated with the microtubule-associated protein tau. Cyclin/Cdk complexes, in addition, exhibit kinase activity towards tau. In vitro , downregulation of cyclins and Cdks by a siRNA approach and by pharmacological inhibition promotes neurite extension. Taken together, these results indicate that the expression of cell cycle-related proteins in terminal differentiated neurons is associated with physiological functions beyond cell cycle control that might be involved in microtubule-based mechanisms of neuroplasticity.