Targeted therapies in the treatment of pancreatic carcinoma

Pancreatic carcinoma is the fifth leading cause of cancer deaths in the western world. Although some progress has been made in the clinical management of pancreatic cancer, surgical resection remains the only potentially curative treatment. New strategies are urgently needed for the treatment of this disease. Advances in knowledge in genetics and molecular biology have led to the development of novel treatments targeting specific molecules. Todate, the results obtained with these new drugs have not been superior to those observed with conventional chemotherapy. In the present article we review some of the new therapies for pancreatic cancer such as the use of inhibitors of epidermal growth factor receptors, the inhibitors of metalloproteases of the extracellular matrix, the inhibitors of farnesyltransferase, and the use of anti-angiogenic treatment. MLA is supported by grant 01/9563 from the Instituto de Salud Carlos III, Madrid, Spain.     

转内皮抑制素基因治疗大鼠角膜新生血管

目的:探讨转染内皮抑制素(Endostatin)基因对酸烧伤引起的大鼠角膜新生血管的基因治疗。方法:通过限制性内切酶酶切反应、聚合酶链式反应、DNA测序及用NCBIBLAST软件与基因库序列比较的方法进行鉴定,鉴定后在大肠杆菌中扩增,用质粒纯化试剂盒抽提纯化;用750g/L硝酸银和250g/L硝酸钾混合烧灼液制作大鼠角膜新生血管模型,用结膜下注射脂质体包裹的质粒pBlast- hEndostatin来进行体内基因治疗。结果:实验证实质粒pBlast-hEndostatin含有人endostatin基因。结膜下注射脂质体包裹的质粒Tel押029-82245172Email押IJO.2000@163.compBlast-hEndostatin对酸烧伤引起的炎症性角膜新生血管有明显抑制作用,术后6,10,15d对角膜新生血管面积的抑制率分别为37%,40%,43%;对角膜新生血管密度也有明显的抑制作用,抑制率达40%。对角膜新生血管长度和角膜炎症细胞没有明显抑制作用。角膜新生血管面积与角膜水肿、角膜混浊呈正相关。结论:用结膜下注射脂质体包裹的内皮抑制素基因可以部分抑制酸烧伤引起的大鼠角膜新生血管。其作用机制是转基因产生的内皮抑制素蛋白直接抑制角膜新生血管的形成,而不是通过抑制炎症反应来抑制角膜新生血管的形成。     

Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors.

BACKGROUND: ZD6474 selectively inhibits the tyrosine kinase activity of vascular endothelial growth factor receptor and epidermal growth factor receptor. The safety, tolerability and pharmacokinetics of ZD6474 were assessed in a phase I dose-escalation study of patients with advanced solid tumors. PATIENTS AND METHODS: Adult patients with tumors refractory to standard treatments received once-daily oral ZD6474 (50-600 mg) in 28-day cycles, until disease progression or unacceptable toxicity was observed. RESULTS: Seventy-seven patients were treated at doses of 50 mg (n=9), 100 mg (n=19), 200 mg (n=8), 300 mg (n=25), 500 mg (n=8), and 600 mg (n=8). Adverse events were generally mild, and the most common dose-limiting toxicities (DLT) were diarrhea (n=4), hypertension (n=4), and rash (n=3). The incidence of most adverse events appeared to be dose-dependant. In the 500 mg/day cohort, 3/8 patients experienced DLT and this dose was therefore considered to exceed the maximum tolerated dose. Pharmacokinetic analysis confirmed that ZD6474 was suitable for once-daily oral dosing. CONCLUSIONS: Once-daily oral dosing of ZD6474 at 300 mg/day is generally well tolerated in patients with advanced solid tumors, and this dose is being investigated in phase II trials.     

多肽mPEG-SC20k-HM-3联合奥沙利铂对人肝癌细胞SMMC-7721裸鼠移植瘤的抑制作用

mPEG-SC_20k-HM-3是具有整合素亲和性的一种新型高效血管生成抑制多肽,为探索其与传统化疗药物联用的抗肿瘤活性,建立人肝癌细胞SMMC-7721裸鼠移植瘤模型,选用奥沙利铂为化疗药物,根据临床前抗肿瘤药效学方法评价联合用药的抑瘤作用,并用金氏公式判断两种药物的联合作用。结果显示,与单独用药相比,联合用药组的抑瘤效果更好,且均具有显著差异(P<0.05)。其中,奥沙利铂(7.5 mg/kg)联合mPEG-SC_20k-HM-3(73.4 mg/kg)的肿瘤抑制率为84.6%,抑制作用比单用奥沙利铂(7.5 mg/kg)和单用mPEG-SC_20k-HM-3(73.4 mg/kg)均有显著提高。根据金氏公式计算,其Q值为1.164(>1.15),可判定该组的用药组合表现出协同作用。结果表明,mPEG-SC_20k-HM-3与奥沙利铂单独给药均能抑制肿瘤生长,两者联用对肝细胞癌具有协同作用。     

RNA干扰酪氨酸激酶受体2对人脐静脉内皮细胞增殖的影响

目的研究抑制酪氨酸激酶受体2（Tie2）对内皮细胞凋亡和增殖活性的影响。方法采用RNA干扰技术,将含有Tie2基因的特异性短发夹状RNA（shRNA）片段的质粒转染入人脐静脉内皮细胞（HUVECs）,采用实时定量逆转录聚合酶链反应和免疫印迹法检测细胞中Tie2 mRNA和蛋白表达的改变;噻唑蓝比色分析（MTT）法检测细胞的生
长情况;显微镜下观察细胞凋亡情况。以转染了pGenesil-hk质粒组为阴性对照,未转染质粒组为空白对照。结果质粒转染入HUVECs后,实验组细胞中Tie2 mRNA和蛋白表达水平较阴性对照组和空白对照组下调,尤以转染后48 h Tie2的mRNA和蛋白表达水平下调更为明显（P<0.05）。MTT检测结果显示：实验组细胞的增殖活性受到明显抑制（P<0.05）。转染48 h后,实验组的细胞凋亡率明显高于两个对照组（P<0.05）。结论RNA干扰技术沉默Tie2基因可致Tie2基因表达下调后诱导HUVECs凋亡,并抑制HUVECs的增殖。     

Cancer gene therapy: developments to 2000

Cancer, at the molecular level, continues to be more thoroughly understood. With this understanding comes the opportunity for innovative therapeutic intervention. Gene therapy remains an attractive concept to treat cancer. However, a number of gene therapy clinical trials have now been reported and it is clear that barriers remain before gene therapy gains widespread clinical application. This article outlines current directions and novel developments in the field of cancer gene therapy, which attempt to overcome these obstacles.     

靶向抗VEGFR治疗恶性肿瘤的研究进展

血管内皮生长因子受体通过与相应的血管内皮生长因子结合刺激血管内皮细胞增殖和迁移,促进新生血管的生成,与机体多种常见肿瘤的发生和转移有着密切的关系。因此以它为靶点,通过现代分子生物学和遗传学等技术方法在基因及细胞分子水平对其表达、活性及其效应等多个环节进行有效抑制而达到治疗肿瘤的目的,是近年来抗肿瘤治疗新的方法和手段之一。本文就抗血管内皮生长因子受体靶向治疗方面的研究做一综述。     

Effects of cloned tumstatin-related and angiogenesis-inhibitory peptides on proliferation and apoptosis of endothelial ceils

Background Tumstatin is a recently developed endogenous vascular endothelial growth inhibitor that can be applied as an anti-angiogenesis and antineoplastic agent.The study aimed to design and synthesize the small molecular angiogenesis inhibition-related peptide (peptide 21),to replicate the structural and functional features of the active zone of angiogenesis inhibition using tumstatin and to prove that synthesized peptide 21 has a similar activity:specifically inhibiting tumor angiogenesis like tumstatin.Methods Peptide 21 was designed and synthesized using biological engineering technology.To determine its biological action,the human umbilical vein endothelial cell line ECV304,the human ovarian cancer cell line SKOV-3 and the mouse embryo-derived NIH3T3 fibroblasts were used in in vitro experiments to determine the effect of peptide 21 on proliferation of the three cell lines using the MTT test and growth curves.Transmission electron microscopy (TEM) and flow cytometry (FCM) were applied to analyze the peptide 21-induced apoptosis of the three cell lines qualitatively and quantitatively.In animal experiments,tumor models in nude mice subcutaneously grafted with SKOV-3 were used to observe the effects of peptide 21 on tumor weight,size and microvessel density (MVD).To initially investigate the role of peptide 21,the effect of peptide 21 on the expression of vascular endothelial growth factors (VEGFs) by tumor tissue was semi-quantitatively analyzed.Results The in vitro MTT test and growth curves all indicated that cloned peptide 21 could specifically inhibit ECV304 proliferation in a dose-dependent manner (P ＜0.01);TEM and FCM showed that peptide 21 could specifically induce ECV304 apoptosis (P ＜0.01).Results of in vivo experiments showed that tumors in the peptide 21 group grew more slowly.The weight and size of the tumors after 21 days of treatment were smaller than those in the control group (P ＜0.05),with a mean tumor inhibition rate of 67.86%;MVD of the tumor tissue in the peptide 21 group was significantly lower than in the control group (P＜0.05);the number of cells positive for VEGF in the peptide 21 group was significantly fewer than in the control group (P ＜0.01).Conclusions Similar to the activity of tumstatin in specifically inhibiting tumor angiogenesis,peptide 21 may specifically inhibit tumor endothelial cell proliferation and induce their apoptosis,thereby suppressing tumor angiogenesis and indirectly inhibit the growth,infiltration and metastasis of tumors.Peptide 21 may exert its effect through down-regulating the VEGF expression of tumor cells and vascular endothelial cells.