紫杉醇诱导黑色素瘤A375细胞凋亡的分子机制

目的:探索紫杉醇对A375细胞的诱导凋亡作用及其机制。方法:采用四甲基偶氮唑蓝(MTT)法检测紫杉醇对细胞增殖能力及细胞生长的影响;流式细胞仪分析及细胞形态学观察检测细胞周期和细胞凋亡;Westernblot方法检测bcl2、Bax和Caspase3蛋白表达。结果:0.001～1.000μmol/L紫杉醇以时间和剂量依赖方式抑制A375细胞生长和诱导细胞凋亡,0.000～1.000μmol/L紫杉醇作用24h时,早期细胞凋亡率由(0.5±0.1)%增至(32.4±1.1)%,P<0.05,0.100μmol/L紫杉醇作用24和48h时,早期细胞凋亡率由(20.9±0.9)%增至(52.6±1.0)%,t=28.89,P=0.001;不同浓度紫杉醇诱导A375细胞凋亡的机制不同,0.001μmol/L时不影响细胞周期,0.010μmol/L时使G0/G1期细胞含量明显减少,0.100和1.000μmol/L时使细胞发生G2/M期阻滞。紫杉醇作用24h后,Caspase3被激活,同时bcl2和Bax蛋白表达分别被下调和上调。结论:紫杉醇可诱导A375细胞凋亡,bcl2/Bax蛋白比值的下降及Caspase3的激活参与了该细胞凋亡过程,但高浓度紫杉醇通过作用微管,低浓度紫杉醇则通过尚不清楚途径实现细胞凋亡过程。     

MMC诱导EJ细胞凋亡和Fas/FasL、Caspase-3基因表达

目的；研究丝裂霉素（MMC）在体外诱导膀胱癌细胞EJ凋亡和凋亡相关基因Fas/FasL,Caspas-3表达的关系。方法：以低剂量MMC（0.100mg/ml)诱导EJ细胞凋亡；以TUNEL法和FCM研究EJ细胞凋亡，细胞周期分布及Caspase-3抗体对抗MMC诱导凋亡；以免疫组化检测Fas/FasL,Caspas-3蛋白表达。结果：低剂量MMC处理的EJ细胞出现明显的凋亡形态特征，凋亡峰和细胞生长阻滞均发生于G0／G1期，Fas/FasL,Caspas-3蛋白呈上调表达，Caspase-3抗体能特异性阻断MMC诱导EJ细胞凋亡。结论；低剂量MMC能够诱导EJ细胞凋亡和增加Fas/FasL,Caspas-3基因表达，且与启动Caspase凋亡信号传导有关。     

DAPK诱导肺癌PGCl3细胞凋亡时Caspases的表达变化

目的:探讨死亡相关蛋白激酶(deathassociatedproteinkinase,DAPK)诱导PGCl3细胞凋亡的可能机制及其对半胱氨酸蛋白酶(Caspases)表达的影响。方法:真核表达载体pcDNA3·1-DAPK导入PGCl3细胞中。荧光染色法观察细胞凋亡,流式细胞仪检测凋亡峰、细胞周期和线粒体膜电位的变化。RT-PCR检测Caspase-3、Caspase-6和Caspase-8表达变化。结果:pcDNA3·1-DAPK转染导致PGCl3细胞发生凋亡。pcDNA3·1-DAPK不影响PGCl3细胞周期和线粒体膜电位,t=1·816,P=0·328。DAPK诱导PGCl3细胞凋亡时,Caspase-3和Caspase-8基因表达上调,Caspase-6基因表达无明显变化。Caspase的抑制剂crmA(100μmol/L)不能完全抑制细胞凋亡,t=0·969,P=0·423。结论:过表达的DAPK诱导PGCl3细胞凋亡与Caspase-8和Caspase-3途径有关,Caspase-6相关途径可能不是主要路径,同时可能存在不依赖于Caspase激活途径。     

三氧化二砷诱导A375细胞凋亡过程中的信号传导途径研究

背景与目的： 探讨三氧化二砷(arsenic trioxide, As2O3)在诱导人黑素瘤A375细胞凋亡中,对NF-κB、C-IAP2以及Caspase-3信号传导途径的影响。 材料与方法： 将As2O3和Caspase-3 抑制剂Ac-devd-cho单独或联合作用A375细胞后,采用Western blot 法检测NF-κB p65和Caspase-3表达水平,免疫组织化学法检测Caspase-3蛋白的表达,RT-PCR法检测C-IAP2 mRNA表达。 结果： 5.0 μmol/L As2O3单独处理A375细胞12 h和24 h以及As2O3联合Ac-devd-cho处理24 h组,随着As2O3作用时间的延长,Caspase-3激活蛋白增多、NF-κB p65核蛋白和C-IAP2 mRNA表达下降,Ac-devd-cho能够阻断Caspase-3蛋白的活化,而对NF-κBp 65核蛋白和C-IAP2 mRNA表达无明显影响;免疫组织化学法也显示,Caspase-3激活型蛋白随着As2O3作用时间的延长而增高,但能被Ac-devd-cho阻断。 结论： As2O3可诱导A375细胞凋亡,能抑制A375细胞NF-κB、C-IAP2基因的表达,且不被Ac-devd-cho所阻断; As2O3能活化Caspase-3蛋白表达,而此效应可被Ac-devd-cho阻断。推测NF-κB-C-IAP2-Caspase-3通路可能是As2O3诱导A375细胞凋亡的途径之一。     

TRAIL 诱导 CHP212 细胞凋亡中 Caspase 8/Caspase 3 活性的变化

目的：探讨Caspase8和Caspase3在肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导神经母细胞瘤细胞株CHP212细胞凋亡中活性的变化。方法：应用流式细胞仪检测TRAIL、Caspase8／Caspase3抑制剂＋TRAIL对CHP212细胞的诱导凋亡作用；比色法测定Caspase8、Caspase3相对活性；透射电镜对凋亡细胞进行形态学观察。结果：TRAIL可诱导CHP212细胞凋亡，并存在剂量依赖性；Caspase8／Caspase3抑制剂能抑制TRAIL对CHP212细胞的诱导凋亡作用。随TRML作用时间的延长，Caspase8、Caspase3活性逐步升高，分别于作用16h、8h后达高峰。透射电镜可见到典型的细胞凋亡特征。结论：TRAIL通过Caspase信号传导通路诱导CHP212细胞凋亡并伴随Caspase8和Caspase3活性增高。     

TRAIL诱导CHP212细胞凋亡中Caspase8／Caspase3活性的变化

目的：探讨Caspase8和Caspase3在肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导神经母细胞瘤细胞株CHP212细胞凋亡中活性的变化。方法：应用流式细胞仪检测TRAIL、Caspase8／Caspase3抑制剂＋TRAIL对CHP212细胞的诱导凋亡作用；比色法测定Caspase8、Caspase3相对活性；透射电镜对凋亡细胞进行形态学观察。结果：TRAIL可诱导CHP212细胞凋亡，并存在剂量依赖性；Caspase8／Caspase3抑制剂能抑制TRAIL对CHP212细胞的诱导凋亡作用。随TRML作用时间的延长，Caspase8、Caspase3活性逐步升高，分别于作用16h、8h后达高峰。透射电镜可见到典型的细胞凋亡特征。结论：TRAIL通过Caspase信号传导通路诱导CHP212细胞凋亡并伴随Caspase8和Caspase3活性增高。     

抗肿瘤药物诱导细胞凋亡机制研究进展

抗肿瘤药物通过诱导肿瘤细胞凋亡而发挥其抗肿瘤活性，其作用机制的研究主要有：①激活Fas／FasL(CD95／Apo-1)信号系统，抗Fas／Apo-1抗体则能降低药物诱导凋产的敏感性。通过DR4、DR5／TRAIL途径诱导细胞凋产。②众多基因参与了细胞凋产。野生型p53抑制细胞增殖．突变型p53抑制细胞凋亡。bcl-2基因过表达与肿瘤多药耐药有关，bcl-2发挥其抑制凋亡的效应需要与其家族的其它成员如bax相互协调。⑧Caspase-3的活化诱导凋产：有些细胞毒药物可直接活化Caspase促使细胞凋亡。     

TRAIL诱导神经母细胞瘤细胞凋亡中 Caspase 8活性的变化

目的：探讨肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导神经母细胞瘤细胞株CHP212细胞凋亡过程中Caspase 8活性的变化.方法：应用流式细胞仪检测TRAIL、Caspase 8抑制剂（zIETD-FMK）＋TRAIL对CHP212细胞的诱导凋亡作用 应用比色法测定Caspase 8相对活性 应用透射电镜对凋亡细胞进行形态学观察.结果：CHP212细胞对TRAIL的诱导凋亡作用敏感，存在剂量依赖性.随TRAIL作用时间的延长，Caspase 8活性逐步升高，于作用16h达高峰 不同浓度TRAIL处理组Caspase 8相对活性随浓度增加而递增.zIETD-FMK能阻断Caspase 8的活化而抑制TRAIL对CHP212细胞的诱导凋亡作用.透射电镜可见到典型的细胞凋亡特征.结论：TRAIL通过Caspase 8信号传导通路诱导CHP212细胞凋亡并伴随Caspase 8活性增高.     

三氧化二砷诱导白血病细胞凋亡作用机制研究进展

三氧化二砷治疗白血病和其他肿瘤的机制主要是通过诱导肿瘤细胞凋亡。其诱导白血病细胞凋亡的途径主要有降解融合蛋白，线粒体途径，激活Caspase家族，抑制NF-κB、细胞增殖和端粒酶活性等。现就其诱导白血病细胞凋亡的作用机制作一综述。     

石蒜碱诱导肺癌NCI-H460细胞凋亡作用及其机制

目的 通过研究石蒜碱在体外对人肺癌NCI-H460细胞增殖抑制和诱导凋亡的作用，探讨石蒜碱抗肿瘤机制。方法 MTT法检测石蒜碱对NCI-H460细胞增殖的抑制作用，流式细胞术检测NCI-H460细胞的凋亡率，比色法检测凋亡因子相关因子Caspase 3活性。结果 石蒜碱能够有效抑制肺癌NCI-H460细胞增殖，IC₅₀为（5.79±0.11）μmol/L，对NCI-H460细胞的凋亡具有诱导效应，可增强肺癌Caspase 3的活性。结论 石蒜碱在体外能有效地抑制NCI-H460细胞增殖并促进其凋亡，其机制可能与激活Caspase 3的表达从而诱导肿瘤细胞凋亡有关。     

Farnesyltransferase inhibitors: antineoplastic properties, mechanisms of action, and clinical prospects

Farnesyltransferase (FTase) inhibitors are among the current wave of molecularly targeted anti-cancer agents being used to attack malignancy in a rational manner. A large body of preclinical data indicates that FTase inhibitors block cancer cell proliferation through both cytostatic and cytotoxic effects. Interestingly, FTase inhibitors have rather limited effects on normal cell function, suggesting that they may target unique aspects of cancer cell pathophysiology. The development of FTase inhibitors was predicated on the discovery that the Ras oncoproteins must be post-translationally modified to transform cells. However, recent work indicates that the anti-neoplastic effects of FTase inhibitors depend on altering the post-translational modifications of non-Ras proteins as well. In particular, a critical target protein that responds to FTase inhibition by blocking tumor cell growth is RhoB, an endosomal Rho protein that functions in receptor trafficking. In this review, we survey the biological foundations for the clinical development of FTase inhibitors, and consider some of the latest mechanistic studies that reveal how these agents affect cellular physiology.     

Targeting tumor vasculature with homing peptides from phage display

Tumor vasculature expresses a number of molecular markers at much lower levels than those seen in the blood vessels of normal tissues, and in some cases, such markers are undetectable. The presence of these markers relates to angiogenesis; the same markers are shared by all blood vessels undergoing angiogenesis. The endothelial cells, pericytes and smooth muscle cells, and the vascular extracellular matrix in angiogenic vessels can each express such markers. Molecularly, they represent vascular growth factor receptors, cell adhesion proteins and their receptors. Screening of phage display libraries for peptides that home to tumor vasculature when injected into mice has recently provided a new tool for analyzing the distinguishing features of tumor vasculature. Tumor-homing peptides isolated in this manner, as well as an antibody against a form of fibronectin expressed in tumor blood vessels, have been found to serve as targeting devices to concentrate drugs and other therapeutic materials to tumors in in vivo models. Such a targeting strategy can therefore potentially improve the efficacy of drugs and reduce their side effects.     

Identification of EBV transforming genes by recombinant EBV technology

Epstein-Barr virus (EBV) is able to infect primary B-lymphocytes but usually does not proceed to replicate more virions. Instead, EBV persists as an incomplete virus and expresses 12 gene products that transform the growth of these cells into continuously proliferating lymphoblastoid cell lines. Because EBV is associated with several human malignancies, there is intense interest in delineating the molecular functions of these EBV gene products in transformation. This review focuses on the recombinant EBV technologies that have been developed to introduce specific mutations into EBV and test the functions of these EBV genes in primary B-lymphocyte growth transformation.     

Matrix metalloproteinases in tumor invasion and metastasis

Extensive work on the mechanisms of tumor invasion and metastasis has identified matrix metalloproteinases (MMPs) as key players in the events that underlie tumor dissemination. Studies using natural and synthetic MMP inhibitors, as well as tumor cells transfected with cDNAs encoding the MMPs characterized thus far have provided compelling evidence that MMP activity can induce or enhance tumor survival, invasion and metastasis. Because of the ability of MMPs to degrade extracellular matrix (ECM) proteins, the principal mechanism whereby MMPs promote tumor development has been thought to be the proteolytic breakdown of tissue barriers to invasion and the associated facilitation of circulating tumor cell extravasation. However, recent evidence stemming from the use of novel experimental approaches indicates that MMPs do not play a major role in the process of extravasation itself. Rather, they appear to promote intravasation (the process of penetrating the circulation following invasion of blood vessels) and regulate the relationship between tumor cells and host tissue stroma subsequent to extravasation. In addition, the discoveries that a growing number of proteolytically active MMPs may localize to the cell surface in association with adhesion receptors, and that MMP substrates include latent cytokines and growth factors, provide a new conceptual framework for the mechanisms whereby MMPs influence tumor behavior.     

New aspects of integrin signaling in cancer

Members of the integrin family of cell adhesion receptors influence several important aspects of cancer cell behavior, including motility and invasiveness, cell growth, and cell survival. Engagement of integrins with extracellular matrix (ECM) proteins can activate members of the Rho-family of small GTPases; conversely, Rho- and Ras-family proteins can influence the ability of integrins to bind their ligands. These events impinge on the control of cell motility, and ultimately on invasive and metastatic behavior. Integrin engagement with ECM also has important effects on cell survival, particularly for cells of epithelial origin. In some cases, specific integrins have selective effects on the efficiency of signal transduction in cell survival pathways.     

Role of LMP1 in immune control of EBV infection

The Epstein-Barr virus (EBV) encoded latent membrane protein (LMP1) plays a crucial role in the long-term persistence of this virus within the cells of the immune system. Not only is this protein critical for the transformation of resting B cells by EBV, it also displays pleiotropic effects on various cellular proteins expressed in the host cell. These include up-regulation of expression of B cell activation antigens, adhesion molecules and various components of the antigen processing pathway. Here we discuss how LMP1 acts like an expression 'switch' which, depending on the stage of EBV infection, manoeuvres various pathways that either modulate the immune system towards or against its survival.     

腹部压块对膈肌运动影响的研究

目的 :研究腹部压块对膈肌运动的影响。方法 :选择拟行立体适形放疗患有肺癌或肝脏肿瘤的患者 2 0例。按治疗体位仰卧于体部立体放疗定位负压袋内 ,待患者呼吸平稳后 ,将灯光野的中心点置于膈顶运动的最低点 ,在膈肌运动至最高位时拍摄照片 ,测量膈肌运动的最大幅度 ;然后 ,将心形腹部压块放置于患者剑突下 ,并用定位框架的腹带交叉固定 ,按压程度以不引起患者呼吸困难或其他不适为标准 ,5min后按上述方法再次测量膈肌运动的最大幅度。结果 :2 0例患者未加腹部压块的运动幅度为0 6 2～ 2 6 7cm ,平均 (1 4± 0 6 4)cm ,加腹部压块后的膈肌运动幅度为 0 2 8～ 2 0 8cm ,平均 (1 0±0 5 5 )cm ,加腹部压块后膈肌运动幅度平均减小 (0 4± 0 34)cm ,P =0 0 0 0。加腹部压块后 90 % (18/2 0 )的患者膈肌运动幅度受到不同程度的限制 ,但有 10 % (2 /2 0 )的患者膈肌运动幅度增加。结论 :腹部压块可使大部分患者膈肌运动的幅度减小 ,但少部分患者例外 ,即腹部压块并不能使所有膈肌周围肿瘤的照射容积减少。建议在制定放射治疗计划前应预先进行测量和评价     

ABCG2在肺癌中表达的定量研究

目的 观察ABCG2在肺癌和癌周肺组织的表达,从量化角度阐明其在肺癌组织中表达的病理学意义.方法 常规石蜡包埋、HE切片确诊,用免疫组化SP法检测ABCG2在肺癌和癌周肺组织的定位和表达,用LeicaQ500MC图像分析系统对其表达强度进行定量分析,并用表达的阳性单位(positive unit PU)反映其表达强度.结果 ABCG2蛋白在肺癌和癌周正常肺组织中的表达主要定位在细胞质和细胞膜.在癌周正常肺组织的支气管和细支气管上皮呈弥漫表达,腺上皮呈灶性表达;肺鳞癌和肺腺癌弥漫或大片表达,肺鳞癌表达的PU值高于肺腺癌(P＜0.001),肺大细胞癌和肺小细胞癌不表达,PU值接近于零.癌周肺组织表达的PU值高于各型肺癌(P＜0.05).ABCG2蛋白表达的PU值在肺癌原发灶和转移灶之间无差别(P＞0.05),且与肺癌患者的性别、年龄、转移和TNM分期未见明显相关性(P＞0.05),与肺癌分化程度有关(P＜0.001).分化程度越高,PU值越高,但高分化肺癌和癌周肺组织的表达PU值差异无显著性(P＞0.05).结论 ABCG2蛋白表达程度与肺癌类型及分化程度具有相关性,可能成为判断其指标之一.     

Telomerase and human tumorigenesis

Human cancer cells, unlike their normal counterparts, have shed the molecular restraints to limited cell growth and are immortal. Exactly how cancer cells manage this at the molecular level is beginning to be understood. Human cells must overcome two barriers to cellular proliferation. The first barrier, referred to as senescence, minimally involves the p53 and Rb tumor-suppressor pathways. Inactivation of these pathways results in some extension of lifespan. However, inactivation of these pathways is insufficient for immortalization. As normal cells undergo repeated rounds of DNA replication, their telomeres shorten due to the inability of traditional DNA polymerases to completely replicate the end of the chromosomal DNA. This shortening continues until the cells reach a second proliferative block referred to as crisis, which is characterized by chromosomal instability, end-to-end fusions, and cell death. Stabilization of the telomeric DNA through either telomerase activation or the activation of the alternative mechanism of telomere maintenance (ALT) is essential if the cells are to survive and proliferate indefinitely. Conversely, loss of telomere stabilization by an already-immortalized cell results in loss of immortality and cell death. Together this indicates that telomere maintenance is a critical component of immortality. In this review we attempt to describe our current understanding of the role of telomere maintenance in senescence, crisis, and tumorigenesis.     

Post-translational regulation of COX2 activity by FYN in prostate cancer cells

While increased COX2 expression and prostaglandin levels are elevated in human cancers, the mechanisms of COX2 regulation at the post-translational level are unknown. Initial observation that COX2 forms adduct with non-receptor tyrosine kinase FYN, prompted us to study FYN-mediated post-translational regulation of COX2. We found that FYN increased COX2 activity in prostate cancer cells DU145, independent of changes in COX2 or COX1 protein expression levels. We report that FYN phosphorylates human COX2 on Tyr 446, and while corresponding phospho-mimetic COX2 mutation promotes COX2 activity, the phosphorylation blocking mutation prevents FYN-mediated increase in COX2 activity.