缓激肽选择性调节血肿瘤屏障的内在基础

目的体外探讨缓激肽的作用靶点细胞及缓激肽选择性开放血脑屏障的可能机制。方法免疫荧光测定脑血管内皮细胞、胶质细胞及C6细胞在不同剂量缓激肽作用前后的细胞内钙离子变化,WesternBlot测定3组细胞的缓激肽B2受体表达水平。结果小剂量缓激肽可以引起肿瘤细胞内的钙离子水平升高,而只有大剂量缓激肽才能触发星形胶质细胞内的钙离子水平变化,脑血管内皮细胞对大、小剂量缓激肽均无任何反应;3组细胞缓激肽B2受体的WesternBlotIDV(integrateddensityvalue)分别为5000.12±1110.21(n=2),18480.88±4119.86(n=3),63032.13±2802.71(n=4),组间比较有显著差异。结论缓激肽的直接作用靶点是星形胶质细胞及肿瘤细胞,两种细胞B2受体表达水平差异是小剂量缓激肽选择性开放血肿瘤屏障的物质基础;缓激肽可能通过某些细胞间信使来起到调节脑血管内皮细胞通透性的作用。     

小剂量缓激肽对C6胶质瘤细胞内钙库释放触发机制的研究

目的:探讨小剂量缓激肽选择性开放血肿瘤屏障的内在机制.方法:细胞原代培养成功后,运用免疫荧光实时测定星形胶质细胞及C6胶质瘤细胞在缓激肽作用前后的细胞内钙离子变化.结果:1×10-6 mol/L BK作用于大鼠C6胶质瘤细胞后出现1个宽广的细胞内钙离子升高期,较长的(>30 s)钙离子波峰的升高期,高峰后存在明显的平台持续期,二次高峰多见,50%的钙离子升高持续时间较长(>50 s);进一步的研究显示,C6胶质瘤细胞上存在功能性的尼诺丁敏感受体,小剂量缓激肽可以引起肿瘤细胞内的钙离子水平升高,特别是首次刺激可以选择性引起尼诺丁受体介导的细胞内钙库释放.结论:首次小剂量缓激肽可以选择性触发C6胶质瘤细胞内的细胞内钙库释放,这可能是小剂量缓激肽可以选择性开放血肿瘤屏障的原因所在.     

星形细胞肿瘤组织COX-2的表达及其与病理分级关系的研究

目的:检测星形细胞肿瘤组织中COX-2的表达,分析其与病理分级之间的关系。方法:应用免疫组化技术并用图像分析系统检测各级别星形细胞肿瘤组织及非肿瘤(脑)组织中COX-2的表达水平。结果:各组免疫组化染色阳性率分别为:肿瘤组织80.0%(36/45),其中毛细胞型星形细胞瘤60.0%(6/10),弥漫性星形细胞瘤76.9%(10/13),间变性星形细胞瘤90.0%(9/10),胶质母细胞瘤91.7%(11/12),非肿瘤(脑)组织28.6%(2/7);免疫组化染色强度(IODA值)分别为:肿瘤组织(6.38±3.68),其中毛细胞型星形细胞瘤(3.54±1.29),弥漫性星形细胞瘤(5.58±2.78),间变性星形细胞瘤(6.88±2.70),胶质母细胞瘤(9.19±4.62),非肿瘤(脑)组织(2.18±0.94)。COX-2在肿瘤组织中的表达显著高于其在非肿瘤(脑)组织中的表达(P=0.017)。结论:COX-2的过表达与星形细胞肿瘤的发生密切相关,并且与肿瘤的病理分级也密切相关;毛细胞型星形细胞瘤与弥漫性浸润性星形细胞肿瘤的遗传基础不同,是一种在生物学和形态学上所发生的基因改变不同于其它胶质瘤的星形细胞肿瘤;COX-2表达改变,为星形细胞肿瘤临床诊断、治疗和预后判断提供了新思路。     

人脑星形细胞肿瘤组织中Survivin基因表达的研究

目的:探讨Survivin mRNA的表达与星形细胞肿瘤发生、发展的关系。方法:应用RT-PCR技术检测各级别星形细胞肿瘤组织及非肿瘤(脑)组织中Survivin mRNA的表达水平。结果:Survivin mRNA在肿瘤组织和非肿瘤(脑)组织中的表达阳性率分别为68.6%和8.3%;Survivin mRNA的相对含量在肿瘤组织和非肿瘤(脑)组织中分别为119.67±46.56和13.19±9.26;Survivin在肿瘤组织中的表达显著高于其在非肿瘤(脑)组织中的表达,P=0.000。结论:Survivin mRNA表达与星形细胞肿瘤的发生、发展呈显著正相关,是评估星形细胞肿瘤恶性生物学行为的可靠指标;Survivin作为凋亡抑制基因为星形细胞肿瘤的治疗提供了一个新靶点。     

给药时间与胶质瘤细胞缓激肽B2受体内化关系的研究

目的研究给药时间与大鼠C6胶质瘤细胞缓激肽(bradykinin, BK)B2受体内化的关系.方法用免疫电镜法和Western-blot法测定不同给药时间下缓激肽B2受体的位置变化和受体在膜上的表达水平.结果给药前细胞膜上缓激肽B2受体表达水平的整合密度值(integrated density value,IDV)为25 767±4 817.01 (n=6),给药10 min B2受体表达水平的IDV为3 528.50±977.86 (n=6),与给药前相比其IDV值最低,仅为给药前表达水平的13.69%,P=0.000, 此时它多见于胞质中.而后B2受体在膜上的表达水平逐渐增加.给药15 min时,IDV为10 233.67±3 428.60 (n=6),P=0.000;20 min时,IDV为14 680.00±3 326.47 (n=6),P=0.000;30 min时,IDV达到17 143.17±2 984.38 (n=6),P=0.001;给药60 min时,细胞膜上B2受体已恢复到给药前表达水平的87.43%,其IDV为22 528.33±6 228.29 (n=6).给药时间与细胞膜上B2受体表达水平的恢复存在线性回归关系, P＝0.000.结论缓激肽B2受体内化是一个短期调节的过程,给药时间与缓激肽B2受体内化水平密切相关,明确两者之间的关系对临床给药方案有一定指导意义.     

同源盒基因在胶质瘤细胞中的表达

目的:观察胶质瘤细胞C6中同源盒基因(Hox基因组)的表达,及苯乙酸(PA)对Hox基因组表达的影响。方法:体外培养C6细胞并用PA诱导分化,提取细胞RNA。用Hox基因三对简并引物P1、P2和P3进行逆转录PCR(RT-PCR)。通过计算机图像分析,Hox基因组mRNA的表达水平用Hox基因(组)/β-肌动蛋白(β-actin)灰度比值表示。应用PA前后基因表达的差异用t检验分析。结果:在胶质瘤细胞C6中,P1、P2和P3组Hox基因表达分别为0.8817±0.0731(n=16),0.6825±0.0987(n=9),0.8608±0.0881(n=16);应用PA后,分别为:0.8765±0.0667(n=8),0.8386±0.0811(n=14),0.8937±0.0598(n=11)。应用PA后,P2组Hox基因表达显著增强,与用药前比较,差异显著(P<0.001)。结论:在胶质瘤C6细胞中,PA对P2组Hox基因mRNA水平的表达有明显的上调作用。PA的作用机理与调节胶质瘤细胞转录过程可能有关。     

四君子汤通过Fas受体诱导小鼠膀胱癌细胞凋亡

目的:探讨中药四君子汤对小鼠膀胱癌BTT739的抗肿瘤作用机制。方法:小鼠膀胱癌细胞接种于T739小鼠皮下,动物抽签法随机分为三组,对照组:生理盐水每次0·15mL,每日2次灌胃;四君子汤小剂量组:四君子汤每次0·15g,每日1次灌胃;四君子汤大剂量组:四君子汤每次0·3g,每日2次灌胃。每组小鼠接种24h后分别给药;用药14d后应用电镜、流式细胞分析技术检测各组小鼠膀胱癌细胞凋亡,流式细胞仪检测肿瘤细胞膜Fas与FasL受体的表达。结果:电镜下可见四君子汤大剂量组小鼠肿瘤组织特征性凋亡细胞的出现,而其他组未出现上述征象;流式细胞仪检测四君子汤大剂量组肿瘤细胞的凋亡峰值为(20·11±1·32)%,四君子汤小剂量组及对照组为(9·33±1·62)%和(5·91±1·84)%,经比较差异有统计学意义,P=0·0001;四君子汤大剂量组肿瘤细胞Fas与FasL的表达为(12·47±0·51)%和(21·3±0·49)%,较其他两组明显增加,P=0·0002。结论:在本实验条件下,大剂量组四君子汤可以诱导小鼠膀胱癌细胞凋亡,死亡受体Fas及FasL的表达增加,可能是四君子汤诱导肿瘤细胞凋亡的重要信息传导途径。     

神经病理性疼痛大鼠脊髓背角小胶质细胞及星形胶质细胞数量的体视学研究

目的探讨坐骨神经慢性限制性损伤（CCI）所致神经病理性痛大鼠脊髓背角内小胶质细胞和星形胶质细胞的数量改变以及帕瑞昔布干预的作用。方法 12只正常成年二级SD大鼠随机分为2组：CCI组（n=7）行单侧坐骨神经松结扎,对侧不做任何处理;帕瑞昔布组（n=5）手术同CCI组,术后3 d连续腹腔注射帕瑞昔布3 mg/kg。术前1 d、术后第4、7、14及28 d测定大鼠50%缩腿阈值（PWT）。术后第28 d测定PWT后取L5脊髓制作石蜡包埋连续切片,按等距随机原则抽选5张切片行GFAP（标记星形胶质细胞）免疫组化染色,采用体视学方法估计脊髓背角内毛细血管腔的面积、星形胶质细胞、少突胶质细胞和内皮细胞的数量。结果 CCI术后4～28 d,CCI组与帕瑞昔布组大鼠手术侧的PWT显著低于对侧未手术侧;帕瑞昔布组手术侧的PWT显著高于CCI组手术侧（P〈0.05）。术后28 d,与未手术侧相比,CCI组和帕瑞昔布组大鼠手术侧脊髓背角内毛细血管的面积无显著改变,单位长度脊髓背角内星形胶质细胞、少突胶质细胞和毛细血管内皮细胞的数量差异无显著性。结论神经病理性痛亚急性期,大鼠脊髓背角无明显的炎症反应,背角内小胶质细胞和星形胶质细胞的数量无改变。     

吴茱萸碱抑制Wnt/β-catenin信号通路诱导骨肉瘤MG-63细胞凋亡

目的 探讨吴茱萸碱对骨肉瘤MG-63细胞增殖与凋亡的影响及其机制.方法 吴茱萸碱作用于骨肉瘤MG-63细胞24h,四甲基偶氮唑蓝(MTT)法检测吴茱萸碱对MG-63细胞的增殖抑制作用.流式细胞术检测吴茱萸碱对细胞周期、细胞凋亡及细胞内钙离子浓度的影响.利用BALB/C小鼠建立骨肉瘤移植瘤模型,观察吴茱萸碱对骨肉瘤模型的生长影响.用Western blotting检测吴茱萸碱对Wnt/β-catenin信号通路蛋白表达的影响.结果 随着吴茱萸碱浓度(0.25 μmol/L、0.5μmol/L、1.0 μmol/L、2.0μmol/L和4.0μmol/L)增加,MG-63细胞抑制率也明显增加[(4.18±1.26)％、(15.49 ±2.26)％、(40.55±6.57)％、(49.87 ±7.69)％和(60.42±8.29)％],2.0 μmol/L组与对照组(0)比较差异有统计学意义(t=-2.66,P＜0.05).2.0 μmol/L吴茱萸碱作用MG-63细胞24 h后凋亡率为(64.67±8.63)％、S期细胞比例为(85.33±9.31)％、钙离子荧光值为97.33±21.31,对照组凋亡率为(4.94±0.81)％、S期细胞比例为(43.67±8.92)％、钙离子荧光值为28.67±8.92,差异均有统计学意义(t=-11.90,P＜0.05;t=-7.22,P＜0.05;t=-6.65,P＜0.05).小鼠模型吴茱萸碱组肿瘤重量为(2.15 ±0.35)g,对照组肿瘤重量为(4.29±0.49)g,差异有统计学意义(t=7.95,P＜0.05).与对照组(1.00 ±0.00)比较,吴茱萸碱可降低β-catenin蛋白表达(0.72±0.36),升高Bax(1.15 ±0.27)、Caspase-3(1.46±0.18)蛋白表达,差异均有统计学意义(t=-3.05,P＜0.05;t=-6.42,P＜0.05;t=-5.85,P＜0.05).结论 吴茱萸碱可以通过抑制Wnt/β-catenin信号通路抑制骨肉瘤MG-63细胞的增殖并诱导其凋亡.     

大麻素受体2在胫骨癌痛大鼠脊髓背角细胞中的表达

目的:观察胫骨癌痛大鼠脊髓大麻素受体2(CB2)表达的变化,探讨CB2在骨癌痛中作用及其可能的脊髓机制。方法:雌性SD大鼠56只,体重160-180g,随机分为7组(n=8):对照组、假手术组、骨癌痛组,假手术组和骨癌痛组又各分为3个亚组(术后7d、14d和21d组),分别用免疫印迹法检测各组大鼠脊髓水平CB2表达的变化,激光共聚焦技术观察CB2的表达部位。结果:免疫印迹结果显示对照组基本没有CB2的表达,与对照组相比,假手术组及骨癌痛组脊髓CB2表达水平升高(P<0.05);与假手术组相比,骨癌痛7d组脊髓CB2蛋白表达明显上调(P<0.05)。激光共聚焦技术显示CB2主要表达于脊髓小胶质细胞和星形胶质细胞。结论:胫骨癌痛大鼠脊髓背角有CB2表达,早期为其表达的高峰,且主要表达于小胶质细胞和星形胶质细胞。     

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.