血管内皮生长因子反义核酸治疗裸鼠皮下种植胰腺癌

目的:探讨抗血管生成基因转染治疗胰腺癌的可行性. 方法:构建反向插入VEGF165cDNA的复制缺陷型腺病毒载体,体外转染SW1990细胞,MTT法检测重组腺病毒转染对细胞生长的影响.Northern blot和ELISA检测转染前后SW1990细胞VEGF的mRNA水平和蛋白表达.裸鼠皮下种植瘤瘤体内注射重组腺病毒,CD31染色观察反义VEGF重组腺病毒转染对裸鼠种植瘤微血管密度和肿瘤生长速度的影响. 结果:重组腺病毒体外转染并不影响SW1990细胞的生长速度.Northern blot和ELISA检测在mRNA水平和蛋白水平证实反义VEGF重组腺病毒转染对体外培养的SW1990细胞内源性VEGF表达有明显的下调作用.体内实验表明反义VEGF重组腺病毒转染可减少肿瘤内微血管数量,肿瘤生长受到抑制. 结论:反义VEGF165重组腺病毒可以抑制胰腺癌的血管生成和肿瘤的生长,为抗血管生成的基因治疗奠定了基础.     

抗VEGF/VEGFR靶向药物的治疗进展

肿瘤微环境在肿瘤的起源、生长和转移中发挥重要作用,而新生血管是肿瘤生长和转移所必需的,血管的生成需要大量调节血管生成的细胞因子参加,而血管内皮生长因子(vascular endothelial growth factor,VEGF)是最重要的促血管生成因子。阻断VEGF通路中某一环节,均有可能有效地抑制肿瘤血管生成,使肿瘤血管退化脱落,产生抗肿瘤作用。根据VEGF的调控特点,已出现多种以VEGF/VEGFR为靶点的抗肿瘤血管生成药物。本文就抗VEGF的靶向药物治疗及特点作一概述。     

胰腺癌微血管的生成机制及其抑制剂的作用

肿瘤微血管生成在胰腺癌的发生转移过程中起重要作用 ,血管内皮生长因子、表皮生长因子、碱性纤维母细胞生长因子等血管生长因子和基质金属蛋白酶反映肿瘤微血管的生长 ,肿瘤微血管的检测和抗血管生成治疗将为胰腺癌的诊断和治疗提供新的手段     

胰腺癌组织中p53、血管内皮生长因子的表达与血管生成的关系及其临床意义

目的探讨胰腺癌组织中p53、血管内皮生长因子(VEGF)和血管生成的关系.方法用免疫组织化学方法检测48例胰腺癌组织及癌旁组织、6例正常胰腺组织中p53、VEGF表达和微血管密度(MVD).结果胰腺癌组织中VEGF、p53的阳性表达率分别为54.17%和50%,显著高于癌旁组织及正常组织的表达率(P < 0.01),胰腺癌组织中MVD显著高于癌旁组织及正常组织.VEGF表达与肿瘤大小和分期有关(P=0.038,P=0.045),VEGF表达与MVD有相关性(r=0.294 P=0.043).p53与淋巴结转移及预后相关(P < 0.05)而与VEGF、MVD之间无关.MVD与胰腺癌临床病理特征无关,MVD与生存期存在负相关(r=-0.371 P=0.011).多元回归分析显示p53、VEGF和MVD都不是影响胰腺癌预后的独立因素.结论 p53基因突变为胰腺癌分子事件的晚期事件,可作为评价胰腺癌预后的一项指标,抗血管生成可能有利于胰腺癌的治疗.     

胰腺癌微血管的生成机制及其抑制剂的作用

肿瘤微血管生成在胰腺癌的发生转移过程中起重要作用，血管内皮生长因子、表皮生长因子、碱性纤雏母细胞生长因子等血管生长因子和基质金属蛋白酶反映肿瘤微血管的生长，肿瘤微血管的检测和抗血管生成治疗将为胰腺癌的诊断和治疗提供新的手段。     

血管内皮生长因子和肺癌

肿瘤血管生成在肺癌的生长和转移中发挥着重要的作用,众多肿瘤血管生成因子和抑制因子参与了肿瘤血管生成的调控,其中,血管内皮生长因子(VEGF)是己知最重要的血管内皮细胞有丝分裂素.本文就肺癌血管生成中血管内皮生长因子的作用机制、诱导因素及其抗血管生成治疗作一简要综述.     

重组腺病毒介导的反义血管内皮生长因子对胰腺癌细胞生长的抑制作用

目的构建表达反义VEGF165的重组腺病毒,探讨腺病毒介导的VEGF165反义核酸治疗胰腺癌的可行性.方法应用基因重组技术,将513 bp的人VEGF1 65 cDNA反向克隆到腺病毒粘粒载体pAxCAwt的Swa I酶切位点.重组粘粒与腺病毒DNA末端肽复合物混合后以磷酸钙共沉淀法转染293细胞,制备出表达反义VEGF165的重组腺病毒.建立胰腺癌裸鼠皮下种植瘤模型,瘤体内直接注射重组腺病毒,观察肿瘤的生长及血管生成情况.结果成功构建了反义VEGF165腺病毒粘粒载体pAxCAwt-αVEGF,并制备出高滴度的反义VEGF165重组腺病毒,注入胰腺癌瘤体内后,治疗组肿瘤生长速度比对照组明显减慢(P＜0.01),治疗组肿瘤微血管密度也明显减少(P＜0.01).结论反义VEGF165重组腺病毒可以抑制胰腺癌的血管生成和肿瘤生长,有潜在的应用价值.     

VEGF和MMP-9在胰腺癌侵袭转移中的表达及临床意义

目的:分析血管内皮生长因子(vascular endothelial growth factor,VEGF)和基质金属蛋白酶9(matrix metalloproteinases-9.MMP-9)在胰腺癌中的表达,探讨血管生成在肿瘤侵袭转移中的差别及意义.方法:选取35例胰腺癌及其癌旁组织、正常组织标本,应用免疫组化方法检测VEGF、MMP-9表达和微血管密度(microvessel density,MVD)计数,并结合病理特点进行分析.结果:VEGF、MMP-9表达阳性率胰腺癌组织较癌旁组织、正常组织差异有统计学意义(VEGF:77.14% vs 5.71%,12.86%,P＜0.01;MMP-9:68.57% vs 8.57%,5.71%,P＜0.01):在大小为＜2 cm、2-4 cm和＞4 cm肿瘤VEGF的阳性率分别为42.86%、92.86%和78.57%.MMP-9的阳性率分别为28.57%、75.00%和83.33%;分化程度高、中、低肿瘤VEGF的阳性率分别为71.43%、70.59%和90.91%,MMP-9的阳性率分别为71.43%、64.71%和72.73%,差异均有统计学意义(P＜0.05).VEGF、MMP-9阳性率在淋巴转移阳性组分别为100%、95.24%,胰腺癌VEGF、MMP-9阳性组与阴性组MVD平均值比较,差异均有统计学意义(t=3.23,P＜0.01;t=3.89,P＜0.01).结论:VEGF、MMP-9与胰腺癌的高血管生成活性相关,VEGF、MMP-9有望成为抗胰腺癌侵犯转移治疗的靶蛋白.     

血管生成与胰腺癌

血管生成(angiogenesis)是指从已有的毛细血管或毛细血管后静脉发展而形成的新的血管。生理状态下,促血管生成因子和血管生成抑制因子处于动态平衡状态。血管生成加速可见于伤口愈合、炎症反应、月经周期和胚胎发育期;在病理情况下,血管生成加速可见于糖尿病、视网膜病变、恶性肿瘤。血管生成主要通过灌注作用、转移作用、相互旁分泌效应促进恶性肿瘤生长、进展和转移。自从Folkman et al首先提出肿瘤的生长取决于血管生成,抗血管生成疗法可用于治疗癌症以来,大量的实验证实,血管生成对肿瘤的诊断、治疗及预后评价具有重大意义。 1 血管生成与胰腺癌 1.1 血管生成与胰腺癌的生长肿瘤的生长有两个明显不同的阶段。即从无血管的缓慢血管生长阶段转变为有血管的快速     

沙利度胺对人胰腺癌细胞细胞动力学和VEGF表达的影响

背景：研究显示沙利度胺及其类似物具有免疫调节、抗血管生成、抗炎等多方面的作用,其对多发性骨髓瘤和一些实体瘤的抗肿瘤作用与其免疫调节活性以及抗血管生成、抗增殖和促凋亡特性有关。目的：观察沙利度胺对人胰腺癌细胞细胞动力学和血管内皮生长因子（VEGF）表达的影响,探讨其用于胰腺癌临床辅助治疗的可能性。方法：以沙利度胺干预人胰腺癌细胞株Patu-898848h,MTT实验检测细胞增殖,流式细胞术检测细胞周期和细胞凋亡,RT—PCR检测VEGFmRNA表达。结果：经不同浓度沙利度胺干预的Patu-8988细胞,生长抑制率、G0／G1期细胞比例和细胞凋亡率均显著高于溶剂对照组（P〈0．05）,VEGF异构体VEGF121、VEGF165mRNA表达显著低于溶剂对照组（P〈0．05）。结论：沙利度胺能从多方面对胰腺癌生长产生抑制作用,包括直接抑制癌细胞增殖、诱导细胞周期G0／G1期阻滞和早期凋亡,以及通过抑制VEGF转录而抑制肿瘤血管发生。     

胰腺癌中三种血管生长因子受体的表达研究

目的：胰腺癌能依赖多种血管生长因子及受体的多步骤调控导致肿瘤血管大量生长。探讨血管内皮生长因子受体（flt-1)，碱性成纤维细胞生长因子受体（bFGFR)及血小板衍生生长因子受体（PDGFR）与胰腺癌生物学行为的关系及受体之间相互关系。方法：应用免疫组化方法检测51例胰腺癌及32例急慢性胰腺炎患者病变组织中，flt-1、bFGFR、PDGFR的表达。结果：flt-1、bFGFR、PDGFR在胰腺癌患者中的阳性率为52．9％，54．9％和45．1％，在胰腺炎中的阳性率为18．8％，18．8％和21．9％，差异均有显著性（P＜0．05或P＜0．01），它们的高表达与胰腺癌的分化程度呈负相关（P＜0．05或P＜0．01），与肿瘤大小无关（P＞0．05）。flt-1、bFGFR、PDGFR在胰腺癌中阳性表达呈相关密切关系（P＜0．05），它们在胰腺癌的发生、浸润、转移中可能存在相互诱导，相互诱导协同或互补作用。结论：flt-1、bFGFR、PDGFR的阳性表达可作为胰腺癌生长，转移及预后的重要判定指标，三种血管生长因子受体可作为胰腺癌抑血管生成治疗的有效靶点。     

Zebrafish model: worth considering in defining tumor angiogenesis

The process of angiogenesis is essential for tumor progression and metastasis; however, antiangiogenesis therapy-induced hypoxia and inflammation are perhaps the driving force for tumor escape and metastasis formation, thereby compromising its efficacy. This warrants the complete understanding of the molecular and cellular basis of antiangiogenesis therapy and necessitates the identification of potential signaling events in the host microenvironment, which are involved in tumor angiogenesis and metastasis, to improve the treatment of cancer. In this context, the zebrafish/tumor xenograft model represents an emerging vertebrate system to study the correlation between tumor angiogenesis, inflammation, and metastasis and to better understand the modification of tumor microenvironment by antiangiogenesis therapy. This review article describes the necessity to study the microenvironment of host-tumor interface by introducing basic concepts of angiogenesis, emerging paradigms, and challenges of antiangiogenesis therapy and provides an update on the importance of the zebrafish/tumor xenograft model to address these issues.     

Recent advances on the molecular mechanisms involved in pancreatic cancer progression and therapies

This review describes the recent advances in the molecular events involved in pancreatic cancer initiation, progression, and metastasis. Additionally, the importance of deregulated cellular signaling elements as potential targets for developing novel therapeutic strategies against incurable forms of pancreatic cancer is reported. The emphasis is on the critical functions gained by numerous growth factors and their receptors, such as epidermal growth factor receptor, hedgehog signaling, and proangiogenic agents such as vascular endothelial factor and interleukin-8 for the sustained growth, survival, and metastasis of pancreatic cancer cells. The molecular mechanisms associated with antitumoral properties and the clinical benefits of gemcitabine alone or in combination with other cytotoxic agents for the treatment of pancreatic cancer are discussed.     

Colorectal cancer and antiangiogenic therapy: what can be expected in clinical practice?

Angiogenesis is a strongly regulated process, which is dependent upon a complex interplay between inhibitory and stimulatory angiogenic factors. It is essential for tumor growth and metastasis: increased angiogenesis is correlated with poor prognosis in cancer patients. Many novel compounds that potently inhibit formation of neoplastic blood vessels have been recently developed. Major categories of angiogenesis antagonists include protease inhibitors, direct inhibitors of endothelial cell proliferation and migration, angiogenic growth factor suppressors, inhibitors of endothelial-specific integrin/survival signalling, copper chelators, and inhibitors with other specific mechanisms. There is increasing interest in developing angio-suppressive agents for colorectal cancer treatment. Some 20 direct and indirect antiangiogenesis drugs are currently being evaluated in clinical trials in colorectal cancer (CRC). Promising results have been reported. These include an increase in overall survival and reduction in the risk of death (Bevacizumab), reversal of cellular resistance (Cetuximab) and activity as second-line therapy in patients who have exhausted other available treatment options (Cetuximab, ABX-EGF, PTK-787, Gefitinib, Erlotinib). This review will outline the mechanisms of action of the principal antiangiogenic drugs, summarize the available data on the use of these new drugs in colorectal cancer, discuss their impact in clinical practice and offer a glimpse into how antiangiogenetic therapy will be integrated into the future care of patients with gastrointestinal cancers.     

Pancreatic Cancer: The Role of Pancreatic Stellate Cells in Tumor Progression

Pancreatic ductal adenocarcinoma is an aggressive and highly lethal disease frequently characterized by a dense stromal or desmoplastic response. Accumulating evidence exists that tumor desmoplasia plays a central role in disease progression and that e.g. activated pancreatic stellate cells (PSCs) are responsible for the excess matrix production. The mechanisms underlying the tumor versus stroma interplay are complex. Pancreatic cancer cells release mitogenic and fibrogenic stimulants, such as transforming growth factor β₁ platelet-derived growth factor (PDGF), sonic hedgehog, galectin 3, endothelin 1 and serine protease inhibitor nexin 2, all of which may promote the activated PSC phenotype. Stellate cells in turn secrete various factors, including PDGF, stromal-derived factor 1, epidermal growth factor, insulin-like growth factor 1, fibroblast growth factor, secreted protein acidic and rich in cysteine, matrix metalloproteinases, small leucine-rich proteoglycans, periostin and collagen type I that mediate effects on tumor growth, invasion, metastasis and resistance to chemotherapy. This review intends to shed light on the mechanisms by which PSCs in the stroma influence pancreatic cancer development. The increased understanding of this interaction will be of potential value in designing new modalities of targeted therapy.     

内皮抑素抑制肿瘤生长和转移的机制

恶性肿瘤的生长和转移离不开新生血管.抗肿瘤血管生成是近年来出现的倍受关注的一种种肿瘤治疗新方法,并得到了较为广泛和深入的研究.内皮抑素是胶原蛋白ⅩⅧ的C末端水解片段,是重要的内源性血管抑制因子,在抗肿瘤血管生成方面表现出显著效果,其为治疗恶性肿瘤提供了新的途径.本文就内皮抑素的生物学特性及其在抑制肿瘤生长和转移作用机制中的研究进展作一介绍.     

Cancer stem cells: Involvement in pancreatic cancer pathogenesis and perspectives on cancer therapeutics

Pancreatic cancer is one of the most aggressive and lethal malignancies. Despite remarkable progress in understanding pancreatic carcinogenesis at the molecular level, as well as progress in new therapeutic approaches, pancreatic cancer remains a disease with a dismal prognosis. Among the mechanisms responsible for drug resistance, the most relevant are changes in individual genes or signaling pathways and the presence of highly resistant cancer stem cells (CSCs). In pancreatic cancer, CSCs represent 0.2%-0.8% of pancreatic cancer cells and are considered to be responsible for tumor growth, invasion, metastasis and recurrence. CSCs have been extensively studied as of late to identify specific surface markers to ensure reliable sorting and for signaling pathways identified to play a pivotal role in CSC self-renewal. Involvement of CSCs in pancreatic cancer pathogenesis has also highlighted these cells as the preferential targets for therapy. The present review is an update of the results in two main fields of research in pancreatic cancer, pathogenesis and therapy, focused on the narrow perspective of CSCs.     

FP therapy for controlling malignant ascites in advanced pancreatic cancer patients

BACKGROUND/AIMS: Malignant ascites is one of the poor prognostic factors for pancreatic cancer, and causes serious symptoms and treatment-related toxicity. We conducted a retrospective analysis to evaluate the efficacy of 5-fluorouracil (5-FU) plus cisplatin (FP therapy) for controlling malignant ascites in patients with advanced pancreatic cancer. METHODOLOGY: This analysis was based on 28 consecutive chemotherapy-naive advanced pancreatic cancer patients with cytologically proven malignant ascites who were treated with FP therapy from November 1991 to April 2003. RESULTS: No patients achieved measurable tumor responses. The objective improvement of ascites was seen in 35.7% of the patients (N = 10/28, 95% confidence interval, 18.0 to 53.4%), but there was no patient with complete disappearance of ascites. The median time to disease progression and the median survival time were 1.7 months and 2.7 months, respectively. In all pretreatment variables, the presence of distant metastasis other than peritoneal dissemination was an unfavorable predictive factor for the objective improvement of ascites (Fisher's exact test: P = 0.002). CONCLUSIONS: FP therapy was modestly effective for controlling malignant ascites but insufficient in shrinking for measurable metastatic lesions. Systemic chemotherapy for controlling malignant ascites might be worth while for palliative management in advanced pancreatic cancer patients, especially in patients without distant metastasis.     

Histologic features of venous invasion, expression of vascular endothelial growth factor and matrix metalloproteinase-2 and matrix metalloproteinase-9, and the relation with liver metastasis in pancreatic cancer

INTRODUCTION: Pancreatic cancer frequently is associated with venous invasion and hematogenous metastasis. AIMS: To determine morphologic features of invaded veins, intratumoral vascular composition, the correlation with liver metastasis, and expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2 and MMP-9, and the mechanism of development of hematogenous metastasis. METHODOLOGY: We examined 32 patients with resected pancreatic cancer: 18 had postoperative liver metastasis, and 14 had no liver metastasis. Specimens were examined to determine the composition of veins and microvessels by staining of victoria-blue and CD34. We also investigated expression of VEGF, MMP-2, and MMP-9 by immunohistochemical staining. RESULTS: Venous invasion was detected in 31 of 32 patients. Invaded venous densities of middle- and large-sized veins were significantly higher in patients with liver metastasis than in those with nonliver metastasis, and they were related to MMP-2 and MMP-9 overexpression. Invaded veins with fragmentation of the lumen through cancer cells were considered to be an intravasation of cancer (destroyed type vein), and their numbers were significantly related to liver metastasis, and MMP-2 and MMP-9 overexpression. CONCLUSION: In conclusion, almost all the patients with pancreatic cancer showed venous invasion, indicating that invasion into large veins and destroyed type veins could be a risk factor for liver metastasis and that increased expression MMP-2 and MMP-9 were related to such invasion.