冬凌草甲素对NB4细胞的生长抑制作用及其作用机制

目的 探讨冬凌草甲素对白血病NB4细胞的生长抑制作用及其作用机制。方法 以不同浓度的冬凌草甲素作用于体外培养的NB4细胞,应用MTF法检测细胞生长抑制率,流式细胞仪检测细胞凋亡率,Hoechst 33258荧光染色法观察细胞凋亡,TRAP-PCR-ELISA法检测细胞凋亡前后的端粒酶活性。结果 8μmol／L以上的冬凌草甲素可显著降低NB4细胞端粒酶活性,抑制细胞的生长及诱导细胞发生凋亡,并呈现出明显的量-效与时-效关系。药物(16μmol／L)作用48～60h在Hoechst染色图片上可见核浓缩及核碎裂等典型的凋亡改变。结论 冬凌草甲素能抑制NB4细胞的生长并诱导细胞发生调亡,降低细胞端粒酶活性可能是其重要作用机制之一;这为冬凌草甲素进一步应用于临床治疗急性白血病提供了有力的试验依据。     

冬凌草甲素对NB4细胞的生长抑制作用及其作用机制(英文)

目的探讨冬凌草甲素对白血病 NB4细胞的生长抑制作用及其作用机制。方法以不同浓度的冬凌草甲素作用于体外培养的 NB4细胞,应用 MTT 法检测细胞生长抑制率,流式细胞仪检测细胞凋亡率,Ho-echst 33258荧光染色法观察细胞凋亡,TRAP-PCR-ELISA 法检测细胞凋亡前后的端粒酶活性。结果 8μmoL/L 以上的冬凌草甲素可显著降低 NB4细胞端粒酶活性,抑制细胞的生长及诱导细胞发生凋亡,并呈现出明显的量-效与时-效关系。药物(16μmol/L)作用48～60h 在 Hoechst 染色图片上可见核浓缩及核碎裂等典型的凋亡改变。结论冬凌草甲素能抑制 NB4细胞的生长并诱导细胞发生调亡,降低细胞端粒酶活性可能是其重要作用机制之一;这为冬凌草甲素进一步应用于临床治疗急性白血病提供了有力的试验依据。     

雷帕霉素诱导人肝癌细胞BEL-7402凋亡中Bcl-2作用研究

目的探讨雷帕霉素(rapamycin,RAPA)体外对肝癌BEL-7402细胞生长抑制及诱导细胞凋亡中的作用及Bcl-2变化在凋亡机制中的意义。方法以5、10、20、30、40和50nmol/L不同浓度的RAPA作用于体外培养的BEL-7402细胞,MTT法检测细胞生长抑制率,应用流式细胞仪检测细胞凋亡,Hoechst33258荧光染色法观察细胞凋亡时的形态学变化,Westernblot观察Bcl-2、Bcl-xl和bax等凋亡相关表达变化。结果RAPA可显著抑制BEL-7402细胞的生长,诱导细胞发生凋亡,并呈现出明显的量-效与时-效关系。RAPA作用肝癌细胞BEL-740248h后,在Hoechst33258荧光染色图片上可见核浓缩及核碎裂等典型的细胞凋亡特征,凋亡过程中伴有抗凋亡蛋白Bcl-2、Bcl-xl表达的降低和促凋亡蛋白bax上调。结论RAPA可能通过诱导抗凋亡蛋白Bcl-2、Bcl-xl表达的降低和促凋亡蛋白bax表达上调而诱导凋亡发生,抑制BEL-7402细胞的生长。     

冬凌草甲素对THP-1细胞的诱导凋亡作用及其作用机制

目的 探讨冬凌草甲素对急性单核细胞白血病THP-1细胞的诱导凋亡作用及其作用机制.方法 以不同浓度的冬凌草甲素(16～56 μmol/L)作用于体外培养的THP-1细胞0、24、48及72 h,应用MTT法检测细胞生长抑制率,用Annexin V/PI双染法检测细胞凋亡,Hoechst 33258荧光染色法观察细胞凋亡时的形态学变化,用免疫印迹法(Western Blotting)检测Caspase-3及其裂解底物多聚(ADP-核糖)聚合酶PARP[(poly(ADP-ribose)polymerase)]表达水平的变化.结果 32 μmol/L以上的冬凌草甲素可显著抑制细胞的生长及诱导细胞发生凋亡,呈现出明显的量效与时效关系,在Hoechst 33258荧光染色后,细胞出现核浓缩及核碎裂等典型的凋亡特征.Western Blotting检测结果表明,Caspase-3被活化出现相对分子质量为20×103的裂解片段,PARP被裂解后出现相对分子质量为89×103的亚单位片段.结论 冬凌草甲素能显著抑制THP-1细胞的生长并诱导细胞发生凋亡,通过激活Caspase-3途径可能是冬凌草甲素诱导细胞发生凋亡的重要作用机制;这为冬凌草甲素用于白血病的辅助治疗提供了有力的实验依据.     

Caspase-3在雷帕霉素诱导肝癌细胞BEL-7402凋亡中的作用

背景与目的:雷帕霉素是从吸水性链霉菌(Streptomyceshygroscopicus)发酵液中提取,最近研究发现雷帕霉素具有免疫抑制作用和广泛的抗肿瘤作用。本研究主要探讨Caspase-3在雷帕霉素诱导肝癌细胞BEL-7402凋亡中的作用。方法:以不同浓度(5、10、20、30、40、50nmol/L)的雷帕霉素作用于BEL-7402细胞,MTT法检测细胞生长抑制率,流式细胞术检测细胞凋亡率,Hoechst33258荧光染色法观察细胞凋亡形态学变化,采用Caspase-3试剂盒和Westernblot蛋白电泳测定Caspase-3活性。结果:雷帕霉素可显著抑制BEL-7402细胞的生长,诱导细胞发生凋亡,具有量-效与时-效关系;雷帕霉素作用BEL-7402细胞48h后,Hoechst33258荧光染色可见核浓缩及核碎裂等典型的细胞凋亡特征;凋亡过程中Caspase-3酶原蛋白的激活,出现20ku亚单位,Caspase-3特异性抑制剂z-DEVD-FMK能阻断凋亡的发生。结论:雷帕霉素能抑制BEL-7402细胞的生长,诱导细胞凋亡发生,Caspase-3酶的激活在雷帕霉素诱导细胞凋亡机制中起到重要作用。     

雷帕霉素对人肝癌细胞BEL-7402体外抗肿瘤作用研究

目的：观察雷帕霉素体外对肝癌细胞BEL-7402生长、细胞凋亡以及细胞转移能力作用。方法：以5nmol／L。10nmol／L，20nmol／L，30nmol／L，40nmol／L和50nmol／L不同浪度的雷帕霉素作用于体外培养的BEL-7402细胞。MTT法检测细胞生长抑制率，应用流式细胞仪检测细胞凋亡。Hoechst 33258荧光染色法观察细胞凋亡时的形态学变化。细胞粘附分析及体外侵袭试验观察肿瘤细胞的转移能力。结果：雷帕霉素可显著的抑制BEL-7402细胞的生长．诱导细胞发生凋亡，并呈现出明显的量-效与时-效关系。雷帕霉素作用肝癌细胞BEL-740248h后，在Hoechst 33258荧光染色图片上可见核浓缩及核碎裂等典型的细胞凋亡特征。雷帕霉素能抑制其粘附性和侵袭性。具有剂量依赖性。随浓度增加而抑制增加。结论：雷帕霉素不仅能诱导BEL-7402肝癌细胞凋亡，抑制细胞的生长。而且同时抑制肿瘤细胞的粘附性和侵袭性．阻止肿瘤细胞的转移，雷帕霉素可能成为一种潜在的抗肝癌药物。     

γ-干扰素对冬凌草甲素抑制白血病K562细胞增殖的影响

[目的] 研究γ-干扰素对冬凌草甲素抑制白血病K562细胞增殖的影响。[方法] 以浓度1000U／ml的γ-干扰素与不同浓度的冬凌草甲素作用于体外培养的K562细胞，观察细胞生长状态的变化。MTT法检测细胞生长抑制率，应用流式细胞仪、台盼蓝染色及Hoechst33258荧光染色法观察细胞凋亡，TRAP-PCR-ELISA法检测细胞凋亡前后的端粒酶活性。[结果] γ-干扰素与冬凌草甲素联合应用可显著抑制K562细胞的生长，诱导细胞发生凋亡，并降低K562细胞端粒酶活性，其作用呈现出明显的量-效与时-效关系。[结论] γ-干扰素与冬凌草甲素联合应用对白血病K562细胞具有明显的增殖抑制作用，降低细胞端粒酶活性足诱导细胞发生凋亡。可能是其重要作用机制之一。     

干扰素α对BEL-7402细胞生长与端粒酶活性影响的观察

目的:探讨干扰素α(IFN-α)对肝癌BEL-7402细胞的生长抑制作用及其对肝癌细胞端粒酶hTERT-mRNA表达水平和端粒酶活性的影响。方法:以不同浓度的IFN-α作用于体外培养的肝癌BEL-7402细胞,MTT法检测细胞生长抑制率,应用流式细胞仪及ho-echst33258荧光染色法观察细胞凋亡;并对细胞凋亡前后的端粒酶hTERT-mRNA表达水平及端粒酶活性进行检测。结果:IFN-α可显著抑制肝癌BEL-7402细胞的生长及诱导细胞发生凋亡,呈现出明显的量-效与时-效关系。在细胞凋亡过程中端粒酶hTERT-mRNA的表达水平及端粒酶活性均显著下降。结论:IFN-α能抑制BEL-7402细胞的生长并诱导细胞发生凋亡,降低端粒酶hTERT-mRNA的表达水平及端粒酶活性可能是其重要作用机制。     

γ-干扰素联合冬凌草甲素对白血病U937细胞的增生抑制作用

目的 :研究干扰素联合冬凌草甲素对白血病 U 937细胞的诱导凋亡作用及其作用机制。方法 :以浓度 2× 1 0 6 U / L的γ-干扰素与不同浓度的冬凌草甲素作用于体外培养的 U 937细胞 ,观察细胞生长状态的变化。 MTT法检测细胞生长抑制率 ,应用流式细胞仪、锥虫蓝染色及 Hoechst332 5 8荧光染色法观察细胞凋亡 ,TRAP- PCR- EL ISA法检测细胞凋亡前后的端粒酶活性。结果 :γ-干扰素与冬凌草甲素联合应用可显著抑制 U937细胞的生长 ,诱导细胞发生凋亡 ,并降低 U937细胞端粒酶活性 ,其作用呈现出明显的量—效与时—效关系。结论 :γ-干扰素与冬凌草甲素联合应用对白血病 U937细胞具有明显的增生抑制作用 ,降低细胞端粒酶活性及诱导细胞发生凋亡 ,可能是其重要作用机制之一。     

冬凌草乙素对白血病NB4细胞的体外诱导凋亡作用研究

目的:探讨冬凌草乙素(PON)对急性白血病NB4细胞的增殖抑制和诱导凋亡作用及其作用机制.方法:以不同浓度的PON(0～50 μmol/L)作用于体外培养的NB4细胞0、24、48及72 h,应用MTT法检测细胞生长抑制率,流式细胞术(FCM)检测细胞凋亡,Hoechst33258染色法检测细胞凋亡时的形态学变化.应用免疫印迹法检测Caspase-3及其裂解底物多聚(ADP-核糖)聚合酶PARP的表达水平,并对凋亡调节蛋白Bax、Bd-2、Bak、Bad及Survivin的表达水平进行检测.结果:>20 μmol/L的PON可显著抑制细胞的生长,并呈现出明显的量-效与时-效关系,FCM检测结果表明,>20 μmol/L的PON作用48 h后,凋亡细胞逐渐增多,在Hoechst染色后可见典型的细胞凋亡现象.蛋白质印迹法检测结果表明,药物作用48 h后Caspase-3被活化出现17×103的亚单位,同时PARP被裂解出现89×103的亚单位片段.蛋白质印迹法检测结果显示,凋亡抑制蛋白Survivin的表达水平明显降低,促凋亡蛋白Bax的表达水平显著升高,而其他凋亡调节基因Bcl-2、Bak、Bad则无明显变化.结论:PON可以通过诱导白血病NB4细胞凋亡而发挥体外抗白血病作用,降低Survivin以及升高Bax的表达水平可能是PON诱导白血病细胞发生凋亡的重要作用机制之一.     

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.