小鼠内皮抑制素原核表达质粒的构建及表达

内皮抑制素具有强烈的抑制新生血管形成的作用，其主要在肝脏合成。提取小鼠肝细胞总RNA，设计合适的引物，用RT－PCR扩增出小鼠内皮抑制素cDNA片段，插入原核表达载体pRSET-A中，构建出重组质粒pRSET-ES。将其转化入大肠杆菌DH5α中扩增，质粒酶切筛选，DNA测序予以证实。重组质粒转化入大肠杆菌BDPS中，经IPTG诱导，SDS－PAGE检测到约19.8ku大小的融合蛋白。     

重组人内皮抑素对小鼠肺腺癌肿瘤血管生成及肺转移的抑制作用

目的观察酵母表达重组人内皮抑素(recombinant human endostatin, rhES)对小鼠肺腺癌LA795原位肿瘤微血管生成及肺转移的抑制作用。方法对含有人内皮抑素基因的重组酵母菌株进行诱导表达及纯化rhES;将接种LA795小鼠肺腺癌细胞的T739小鼠随机分成两组,每组各10只,于接种后第6日起给予rhES和磷酸缓冲盐液(PBS)皮下注射,每日1次,连续14 d;观察两组小鼠原位肿瘤微血管生成情况及肺部肿瘤转移情况。结果经甲醇诱导酵母转化子表达rhES,并用肝素亲和层析的方法获得纯化的rhES;治疗结束后用免疫组化方法观察两组小鼠原位肿瘤微血管密度发现rhES治疗组肿瘤微血管密度明显小于PBS对照组(P<0.01);观察两组小鼠肺部发现rhES治疗组小鼠肺部未见有明显肿瘤转移病灶,而PBS对照组小鼠肺部可见大量散在肿瘤转移病灶;两组小鼠肺湿重比较具有显著性差异(P<0.01)。结论rhES具有良好的生物学活性,显著抑制了小鼠肺腺癌LA795肿瘤血管生成,并能有效抑制肿瘤的肺部转移。     

The Wnt-dependent signaling pathways as target in oncology drug discovery

Summary Our current understanding of the Wnt-dependent signaling pathways is mainly based on studies performed in a number of model organisms including, Xenopus, Drosophila melanogaster, Caenorhabditis elegans and mammals. These studies clearly indicate that the Wnt-dependent signaling pathways are conserved through evolution and control many events during embryonic development. Wnt pathways have been shown to regulate cell proliferation, morphology, motility as well as cell fate. The increasing interest of the scientific community, over the last decade, in the Wnt-dependent signaling pathways is supported by the documented importance of these pathways in a broad range of physiological conditions and disease states. For instance, it has been shown that inappropriate regulation and activation of these pathways is associated with several pathological disorders including cancer, retinopathy, tetra-amelia and bone and cartilage disease such as arthritis. In addition, several components of the Wnt-dependent signaling pathways appear to play important roles in diseases such as Alzheimer’s disease, schizophrenia, bipolar disorder and in the emerging field of stem cell research. In this review, we wish to present a focused overview of the function of the Wnt-dependent signaling pathways and their role in oncogenesis and cancer development. We also want to provide information on a selection of potential drug targets within these pathways for oncology drug discovery, and summarize current data on approaches, including the development of small-molecule inhibitors, that have shown relevant effects on the Wnt-dependent signaling pathways.     

Downregulation of vascular endothelial growth factor and integrinbeta3 by endostatin in a mouse model of retinal neovascularization

Retinal neovascularization is among the leading causes of vision impairment throughout the world. Intraocular expression of vascular endothelial growth factor (VEGF), an angiogenic protein, and integrins, a group of cell adhesion molecules, is closely correlated with neovascularization in such neovascular diseases. The purpose of this study is to determine the effect of endostatin, a potent anti-angiogenic factor, on gene expression of vascular endothelial growth factor (VEGF) and integrinbeta3 in a mouse model of oxygen-induced retinopathy. C57BL/6 mice were given intravitreous injections of 1.0 microg endostatin at P12. At P17, retinal VEGF and integrinbeta3 mRNA levels were measured by real-time quantitative PCR in the hyperoxia mice and in the endostatin-treated mice. Analysis of 12 separate experiments revealed a 3.5-fold decrease in VEGF levels between hyperoxia mice and endostatin-treated mice (p<0.01) and a 2.5-fold decrease in integrinbeta3 levels between hyperoxia mice and endostatin-treated mice (p<0.01). These data suggest that intraocular expression of VEGF and integrinbeta3 mRNA is down-regulated by endostatin, which may provide a new therapeutic approach for ocular neovascularization.     

Pretreatment serum endostatin as a prognostic indicator in metastatic gastric carcinoma

Endostatin is the C-terminal antiangiogenic fragment of the extracellular matrix protein collagen XVIII, and is generated by tumor-derived proteases. The presence of serum endostatin in patients with gastric cancer has not been reported. The authors assessed the serum levels of endostatin in patients with gastric carcinoma and evaluated their association with the levels of vascular endothelial growth factor (VEGF) and the clinical outcome. A total of 107 patients with gastric cancer were included in the study. Pretherapeutic serum levels of endostatin and VEGF were measured using an ELISA, and compared with those in 23 healthy controls. The serum levels of endostatin and VEGF were higher in gastric cancer patients than in healthy controls (endostatin, 70.1 +/- 16.6 vs. 52.2 +/- 6.2 ng/mL [p < 0.001]; VEGF, 55.1 +/- 7.6 vs. 32.1 +/- 2.4 ng/mL [p < 0.001]; mean +/- SD). Serum endostatin levels were significantly associated with the presence of distant metastases (r = 0.556, p < 0.001) and VEGF levels (r = 0.335, p < 0.001), but not with the depth of tumor invasion, differentiation, or regional lymph node status. A serum endostatin level above the 75th percentile of the distribution for the patients (79.2 ng/mL) was associated with a poor outcome (last follow-up at 42 months; median survival time, 9 vs. 20 months [log-rank, p = 0.017]; median time to progression, 5 vs. 10 months [log-rank, p = 0.022]) in the patients with metastatic gastric cancer. The results suggest for the first time that an elevated serum level of endostatin at the diagnosis of metastatic gastric cancer could be predictive of a poor outcome.     

Endostatin expression in pancreatic tissue is modulated by elastase

Pancreatic tumours are scirrhous, avascular tumours, suggesting that they may produce angiogenesis inhibitors that suppress the growth of the vasculature to the tumour and metastases. We have sought evidence for the angiogenesis inhibitor, endostatin, in normal and cancerous pancreatic tissue. Using Western blotting, we found mature 20 kDa endostatin in cancer tissue but not in normal tissue. Several endostatin-related peptides of higher mol wt were present in both tissues. Extracts from normal tissue were able to degrade exogenous endostatin, whereas extracts from cancer were without effect. Although the exocrine pancreas secretes inactive proenzymes of trypsin, chymotrypsin and elastase, their possible role in this degradation was examined. The trypsin/chymotrypsin inhibitor, Glycine max, did not prevent the degradation of endostatin by normal pancreatic extracts but elastatinal, a specific inhibitor of elastase, reduced the rate of degradation. Extracts of pancreatic tumours did not express any detectable elastase activity, but an elastase (Km 1.1 mM) was expressed by extracts of normal pancreas. We conclude that endostatin is present and stable in pancreatic cancer tissues, which may explain their avascular nature, but that normal pancreatic tissue expresses enzymes, including elastase, which rapidly degrade endostatin. The stability of endostatin may have implications for its therapeutic use.     

TRAIL和endostatin双基因-放射治疗对人血管内皮细胞增殖、周期和凋亡的影响

目的：观察重组质粒pshuttle-Egr1-shTRAIL-shES携带的双基因TRAIL和endostatin联合X射线照射后,对血管内皮细胞ECV304增殖、周期和凋亡的影响。方法：实验分为对照组、空载体pshuttle转染组、TRAIL单基因重组质粒pshuttle-Egr1-shTRAIL转染组、endostatin单基因重组质粒pshuttle-Egr1-shES转染组和TRAIL、endostatin双基因重组质粒pshuttle-Egr1-shTRAIL-shES转染组。细胞转染采用脂质体介导的方法进行,对照组不转染。细胞转染后给予X射线照射（照射剂量分别为0、0.1、0.5、1.0、2.0和5.0 Gy）,采用ELISA法检测转染细胞中TRAIL和endostatin蛋白的表达,并分别采用MTT及PI单染或/和Annexin Ⅴ双染流式细胞术（FCM）检测TRAIL、endostatin单/双基因治疗联合放射治疗对ECV304细胞增殖、细胞周期和凋亡的影响。结果：2.0 Gy X射线照射后与0 h比较,各时间点转染pshuttle-Egr1-shTRAIL-shES的ECV304细胞上清中TRAIL和endostatin蛋白表达水平明显升高（P<0.01）,分别于12和24 h达峰值;不同剂量X射线照射可诱导TRAIL和endostatin蛋白表达,且蛋白表达水平随照射剂量的增加而明显升高（P<0.05或P<0.01）。MTT结果显示,X射线照射后, pshuttle-Egr1-shTRAIL、pshuttle-Egr1-shES和pshuttle-Egr1-shTRAIL-shES组ECV304细胞A490值均明显低于对照组和pshuttle组,并显示一定的时间-效应和剂量-效应关系,并伴有细胞凋亡率明显增加、G₂+M期细胞百分数明显上升和G₀/G₁期细胞百分数明显下降。上述细胞效应,尤以pshuttle-Egr1-shTRAIL-shES组变化最为明显,与pshuttle-Egr1-shTRAIL和pshuttle-Egr1-shES组比较差异有统计学意义（P<0.05 或 P<0.01）。结论： TRAIL和endostatin双基因联合放射治疗可抑制ECV304细胞生长,影响细胞周期进程,促进细胞凋亡,且其治疗效果优于单纯放射治疗或TRAIL/endostatin单基因-放射治疗。     

乳化溶剂挥发法制备重组人血管内皮抑制素缓释微球

目的:制备重组人血管内皮抑制素(恩度)缓释微球,并对微球理化性质及体外释放行为进行初步考察。方法:采用乳化溶剂挥发法(W/O/O)制备恩度载药微球;对微球载药量、粒径、突释、体外释放速率及降解行为进行考察,同时利用凝胶电泳初步评价体外释放过程中恩度的完整性。结果:增加聚乳酸-羟基乙酸嵌段共聚物(PLGA)中羟基乙酸的比例、提高PLGA浓度、降低内水相体积、提高理论载药量均增加微球载药能力;降低内水相体积、提高分散速度均减小突释。增加PLGA中羟基乙酸的比例,30 d时累积释放可增加到65%。降解实验说明释放初期微球主要以扩散方式释放恩度,释放后期主要表现为微球的降解。凝胶电泳结果表明微球制备过程对蛋白质聚集性的影响不大。结论:用PLGA作为载体材料制备微球,可以延缓恩度的释放。     

Patent focus on cancer chemotherapeutics. IV Angiogenesis agents: April 2001 - August 2001

Angiogenesis refers to the formation of capillary blood vessels from existing blood vessels: a process that is believed to be a key driver in cancer growth and metastasis. Angiogenesis inhibition represents an active area of cancer drug discovery, with several agents and approaches now entering late clinical development. This review summarises the key aspects of recent patent applications referring to cancer chemotherapy and cancer drug discovery that involve inhibition or modulation of angiogenesis. The scope includes applications that have been published between April and August 2001. The review covers the main mechanism-based approaches such as MMPIs, inhibitors of the growth factor signalling pathways, integrin antagonists and urokinase inhibitors.