抗肿瘤新生血管治疗的新进展

血管新生是肿瘤生长、转移的重要条件。在导致肿瘤血管新生的因素中,血管内皮生长因子(vascular endothelialgrowth factor,VEGF)被认为是最重要的因素。抑制VEGF的信号转导有可能抑制血管新生,并进一步抑制肿瘤生长。目前有几种新的可能抑制VEGF信号转导的方法,其中包括基因水平上抑制VEGF及VEGF受体(VEGF receptor,VEGFR)的表达、中和血液循环中的VEGF或VEGFR,以及抑制VEGFR的酪氨酸激酶活性以达到抑制其下游的信号转导等。迄今为止,已报道多种针对VEGF抗血管新生的生物及化学制剂,部分已应用于临床,其他制剂正在进行动物试验或临床试验。本文对抑制VEGF信号转导在抗肿瘤治疗中的研究新进展做一综述。     

血管内皮生长因子和Notch信号通路与肿瘤血管生成

血管内皮生长因子(VEGF)和Notch信号通路是血管发育及肿瘤血管生成的重要机制.阻断VEGF可抑制肿瘤生长和血管生成.Notch能抑制内皮形成尖端细胞,减少血管生成.实验证明,两条通路相互作用,联合阻断VEGF和Notch信号通路可协同抑制肿瘤生长.对VEGF和Notch通路的研究,将为肿瘤临床治疗提供新的方法.     

VEGF及其在肺癌抗血管生成中的研究进展

临床研究表明,血管内皮生长因子（VEGF）在肺癌血管生长中起着重要作用。肿瘤生长、浸润和转移都依赖于肿瘤血管的生成,而持续表达的VEGF是肿瘤血管生成和肿瘤进展的关键介导因子,通过阻断VEGF信号来抑制血管新生是肿瘤治疗的重要措施之一。     

EGCG对胃癌血管新生中VEGF信号通路的多靶点作用

目的:探讨EGCG对胃癌血管生成抑制作用及其信号通路。方法:建立裸鼠异位胃癌模型,经腹腔注射EGCG,检测肿瘤生长及肿瘤组织微血管密度;不同浓度EGCG处理胃癌细胞24 h,检测胃癌VEGF蛋白和mRNA表达及VEGF分泌;同时不同浓度EGCG处理脐静脉内皮细胞,检测内皮细胞生长、迁移和体外小管形成。结果:EGCG显著抑制胃癌生长和肿瘤血管生成,平均肿瘤抑制率60.4%;EGCG显著抑制胃癌VEGF蛋白、mRNA表达和VEGF分泌;EGCG时间和剂量依赖性地抑制VEGF诱导的内皮细胞增殖,同时也剂量依赖性地抑制VEGF诱导的内皮细胞的迁移和小管生成。结论:EGCG多靶点作用于VEGF信号通路,抑制胃癌生长和血管生成。     

EGCG对胃癌血管新生中VEGF信号通路的多靶点作用

目的：探讨EGCG对胃癌血管生成抑制作用及其信号通路。方法：建立裸鼠异位胃癌模型,经腹腔注射EGCG,检测肿瘤生长及肿瘤组织微血管密度;不同浓度EGCG处理胃癌细胞24 h,检测胃癌VEGF蛋白和mRNA表达及VEGF分泌;同时不同浓度EGCG处理脐静脉内皮细胞,检测内皮细胞生长、迁移和体外小管形成。结果：EGCG显著抑制胃癌生长和肿瘤血管生成,平均肿瘤抑制率60.4%;EGCG显著抑制胃癌VEGF蛋白、mRNA表达和VEGF分泌;EGCG时间和剂量依赖性地抑制VEGF诱导的内皮细胞增殖,同时也剂量依赖性地抑制VEGF诱导的内皮细胞的迁移和小管生成。结论：EGCG多靶点作用于VEGF信号通路,抑制胃癌生长和血管生成。     

EGCG对肿瘤生物抑制机制影响的探讨

目的:探讨表没食子儿茶素没食子酸酯(EGCG)通过抑制血管内皮生长因子(VEGF)的血管生成效应减少肿瘤生长和血管生成。方法:MTT法检测内皮细胞生长、Transwell检测内皮细胞迁移,同时检测内皮细胞体外小管形成情况及Matrigel胶塞体内实验检测体内血管生成情况;建立异位胃癌裸鼠模型,检测肿瘤生长及肿瘤组织微血管密度,明确EGCG对肿瘤生长和血管生成的抑制作用及其机制。结果:体外实验显示,随着EGCG处理时间和剂量的增加,VEGF诱导生长的内皮细胞数呈时间和剂量依赖性地减少;随着EGCG剂量的增加,VEGF诱导迁移的内皮细胞数和形成的小管样结构也剂量依赖性地减少,差异有统计学意义,P<0.05;Matrigel胶塞体内实验也显示EGCG抑制VEGF诱导的胶塞血管化;动物实验显示治疗组肿瘤生长缓慢,生长曲线明显低于对照组,平均肿瘤抑制率为60.4%,P<0.01;治疗组肿瘤组织微血管密度显著降低,P<0.01。结论:EGCG可以抑制VEGF诱导的血管生成,从而抑制肿瘤生长和血管生成。     

血管内皮生长因子与乳腺癌靶向治疗的研究进展

血管形成在乳腺癌的转移中起着重要的作用,血管内皮生长因子(VEGF)是主要的促血管形成因子.抑制血管生成的靶向治疗正在成为治疗乳腺癌的一个新策略,重组人源性抗VEGF单克隆抗体贝伐单抗(rhMAb VEGF、Bevacizumab、Avastin)正是通过抗VEGF作用而抑制肿瘤血管生成.本文就VEGF与乳腺癌靶向治疗的研究进展作一综述.     

靶向VEGF治疗恶性肿瘤的研究进展

血管生成是肿瘤生长、侵袭、转移的基础。目前,研究表明VEGF及其家族成员在肿瘤的血管生成中发挥着重要作用。抑制VEGF的表达、活性和其下游信号传递可取得明显的抗肿瘤效应,表明VEGF是一个有效的肿瘤治疗靶点。     

薏苡仁注射液对小鼠移植性S180肉瘤血管形成抑制的作用

 目的　探讨薏苡仁注射液对肿瘤血管形成抑制作用。方法　通过建立动物肿瘤模型 ,运用薏苡仁实验治疗 ,检测其抑瘤率和肿瘤内血管密度 ,以及瘤体VEGF和bFGF表达的改变。结果　薏苡仁具有明显的抑制S180肉瘤生长作用。实验组的S180瘤体内微血管密度均明显低于对照组 ;免疫组化显示薏苡仁大、中剂量组均可下调S180瘤体内VEGF、bFGF的表达。结论　薏苡仁注射液对肿瘤血管形成均有明显抑制作用 ,降低VEGF、bFGF的表达可能是其抑制肿瘤血管形成的主要机制之一。     

VEGF与骨肿瘤抗血管生成治疗进展

VEGF和VEGFR因其在肿瘤血管生成中的重要作用而成为抗肿瘤血管生成疗法的重要靶点.目前应用单克隆抗体、小分子抑制物、可溶性受体等方法通过阻断其信号转导通路或耗竭肿瘤细胞产生的VEGF,使VEGF或VEGFR表达减少,从而抑制肿瘤血管生成,切断肿瘤血供,最终达到抑制肿瘤生长及转移的作用.全文综述了VEGF及VEGFR研究历程、分子结构及其最近几年在抗血管生成治疗方面的最新进展和应用前景.     

Avastin对胃癌裸鼠原位移植模型血管生成的影响

背景与目的:血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)和肿瘤的生长和转移密切相关,本实验通过VEGF单克隆抗体Avastin联合或不联合氟尿嘧啶(5-fluorouracil,5-FU),对人类胃癌裸鼠原位种植模型的肿瘤生长和转移进行干预治疗,从而探讨Avastin对胃癌生长、转移和血管生成的抑制作用。方法:应用原位移植方法建立裸鼠胃癌转移模型,术后10天将裸鼠随机分为4组:对照组、5-FU单药组、Avastin单药组和联合用药组。经过6周的治疗,对裸鼠原位肿瘤的瘤重、抑瘤率、肿瘤微血管密度、凋亡指数以及肝脏转移灶进行检测和分析。结果:和对照组相比,5-FU单药组、Avastin单药组和联合用药组原位移植肿瘤重量明显降低,抑瘤率分别为37.52%,58.76%和98.51%。微血管密度Avastin单药组和联合用药组均比对照组明显减少(8.40±1.26和7.20±1.23vs15.30±1.06),而5-FU组与对照组之间没有显著的差别;Avastin单药组和联合用药组的凋亡指数比对照组明显升高[(11.50±1.58)%和(13.60±1.35)%vs(4.70±1.70)%]。联合应用Avastin和5-FU对肝脏转移灶具有明显的抑制作用,而其他3组的抑制肝转移效果没有明显的差别。结论:抗VEGF抗体Avastin通过抑制肿瘤新生血管的生成而诱导胃癌细胞凋亡,进而显著抑制裸鼠原位肿瘤的生长。联合应用Avastin和5-FU不仅对原位肿瘤的生长抑制最为明显,而且对肝脏转移有显著的抑制作用。因此,联合应用Avastin和传统的细胞毒化疗药物对胃癌的治疗效果更显著。     

Avastin阻断VEGF促横纹肌肉瘤细胞株RH4增殖的作用

背景与目的：血管内皮生长因子（vascular endothelial growth factor,VEGF）及其通路的研究是目前研究的热点之一,但其在横纹肌肉瘤中的研究鲜有报道．其作用机制尚不完全清楚。本研究通过检测横纹肌肉瘤细胞株RH4中VEGF及其受体的表达情况,以了解VEGF在横纹肌肉瘤中的作用及机制,并研究Avastin阻断VEGF促细胞增殖的作用。方法：使用RT-PCR方法检测RH4细胞株中VEGF、VEGFR1、2、3mRNA的表达：使用ELISA方法检测培养液上清中VEGF的分泌水平;使用Western blot方法检测VEGFR1蛋白的表达水平;使用直接计数的方法检测VEGF、Avastin对RH4细胞增殖的影响。结果：RT-PCR和ELISA结果显示在RH4细胞中存在VEGF的表达和分泌;在RH4细胞中仅有VEGFR1表达,VEGFR2和VEGFR3均为阴性：Western blot的结果进一步证实了VEGFR1在RH4中的表达。VEGF可直接促进RH4细胞的增殖,在0～100ng／ml的区间其促进增殖的作用随着浓度的增加而增加。10～40μg／ml Avastin可以阻断VEGF的促增殖作用。结论：在横纹肌肉瘤细胞RH4中VEGF可以通过自分泌的方式作用于自身,并通过VEGFR1促进肿瘤细胞的增殖,Avastin可以阻断VEGF的促增殖作用。     

活体观察贝伐单抗对人骨肉瘤裸鼠移植瘤模型的作用

目的 探讨贝伐单抗（Avastin）对人骨肉瘤143-B裸鼠移植瘤模型生长和血管生成的影响。方法 将成功建立的红色荧光蛋白标记的人骨肉瘤143-B裸鼠原位种植模型随机分为3组：对照组（生理盐水）、低剂量贝伐单抗组（Avastin-L,2.0mg/kg）和高剂量贝伐单抗组（Avastin-H,5.0mg/kg）,每组7只。贝伐单抗每次腹腔注射0.2ml,1周2次,持续3周;对照组给予等体积生理盐水。每隔3天记录各组体质量,每隔7天用荧光影像系统测量原位肿瘤大小并计算抑瘤率;采用免疫组化En Vision法检测各组肿瘤组织中的CD34表达并计算微血管密度（MVD）;酶联免疫吸附法检测各组血浆和肿瘤组织的血管内皮生长因子（VEGF）的水平。结果 3组实验裸鼠体质量及肺部转移率的差异无统计学意义（P＞0.05）;与对照组相比,Avastin-L组和Avastin-H组的肿瘤体积减小,MVD、血浆及肿瘤组织的VEGF水平降低,差异均有统计学意义（P＜0.05）;Avastin-H组对上述指标的改善程度优于Avastin-L组（P＜0.05）。结论 Avastin对人骨肉瘤143-B肿瘤生长有抑制作用,同时可降低血管生成及VEGF水平,但对肺部转移无明显抑制作用。     

Cancer and Leukemia Group B 90206: A randomized phase III trial of interferon-alpha or interferon-alpha plus anti-vascular endothelial growth factor antibody (bevacizumab) in metastatic renal cell carcinoma.

The majority of sporadic clear cell renal cell carcinoma (RCC) is characterized by loss of heterozygosity of the von Hippel-Lindau (VHL) tumor suppressor gene and somatic inactivation of the remaining VHL allele. The resulting VHL gene silencing leads to induction of hypoxia-regulated genes including vascular endothelial growth factor (VEGF). Thus, therapeutic inhibition of VEGF holds promise for treatment of this historically refractory malignancy. An antibody to VEGF (bevacizumab, Avastin) has demonstrated a significant prolongation of time to disease progression compared with placebo in patients with metastatic RCC. Interferon-alpha (IFN-alpha) is a standard initial cytokine therapy in RCC with a modest response rate and a survival advantage demonstrated in randomized trials. We hypothesized that the addition of anti-VEGF therapy to IFN-alpha would prolong survival in untreated metastatic RCC patients. A Phase III trial is now being conducted randomizing untreated, metastatic clear cell RCC patients to IFN-alpha alone or IFN-alpha plus Avastin.     

The VEGF signaling pathway in cancer: the road ahead

The vascular endothelial growth factor (VEGF) family of soluble protein growth factors consists of key mediators of angiogenesis and lymphangiogenesis in the context of tumor biology. The members of the family, VEGF-A (also known as VEGF), VEGF-B, VEGF-C, VEGF-D, and placenta growth factor (PlGF), play important roles in vascular biology in both normal physiology and pathology. The generation of a humanized neutralizing antibody to VEGF-A (bevacizumab, also known as Avastin) and the demonstration of its benefit in numerous human cancers have confirmed the merit of an anti-angiogenesis approach to cancer treatment and have validated the VEGF-A signaling pathway as a therapeutic target. Other members of the VEGF family are now being targeted, and their relevance to human cancer and the development of resistance to anti-VEGF-A treatment are being evaluated in the clinic. Here, we discuss the potential of targeting VEGF family members in the diagnosis and treatment of cancer.     

Challenges for patient selection with VEGF inhibitors

As targeted therapies for cancer become increasingly integrated into standard practice, appropriate selection of the patients most likely to benefit from these therapies is now receiving critical scrutiny. Early experience with therapies directed at targets that are definitively overactive (e.g. the bcr-abl tyrosine kinase targeted by imatinib) or over-expressed [e.g. the human epidermal growth factor receptor 2 (HER2) targeted by trastuzumab] has generated the perception that pre-treatment target assessment is a pre-requisite for therapy with all targeted agents. However, emerging evidence suggests that this is not presently feasible for anti-angiogenic agents. Despite considerable evidence for the association of intratumoral and/or plasma vascular endothelial growth factor (VEGF) levels with tumor progression and/or poor prognosis, pre-treatment VEGF levels do not appear to be predictive of response to anti-angiogenic therapy. This may possibly be due to the complexity of the angiogenic pathways and the limitations associated with current methods of VEGF detection and quantification; e.g. low assay sensitivity and lack of standardized methods could prevent detection of very small increases in VEGF, which may be clinically important in patients with tumors that are highly dependent on this growth factor. In addition to a general lack of agreement as to the relative clinical relevance of circulating versus tumor VEGF levels, the absence of a 'gold standard' VEGF detection assay and the lack of a predefined, clinically relevant cut-off pose a significant hindrance to the clinical utility of VEGF measurements for therapy selection. Given the fundamental importance of angiogenesis for tumor growth and progression, and the key role of VEGF in these processes, presently it seems appropriate to view anti-VEGF agents such as bevacizumab (Avastin) as having potential utility, independently of pre-treatment screening. Further research is needed to define the relationship between potential surrogate markers of VEGF pathway activity and clinical outcomes.     

Inhibition of carcinoma cell-derived VEGF reduces inflammatory characteristics in xenograft carcinoma

The stroma of carcinomas shares several characteristics with inflamed tissues including a distorted vasculature, active angiogenesis and macrophage infiltration. In addition, the tumor interstitial fluid pressure (P(IF)) of the stroma is pathologically elevated. We show here that bevacizumab [rhuMab vascular endothelial growth factor (VEGF), Avastin], a monoclonal antibody to VEGF, at a dose of 5 mg/kg modulated inflammation in KAT-4 xenograft human anaplastic thyroid carcinoma tissue. At this dose, bevacizumab reduced the density of macrophages, MHC class II antigen expression by macrophages and IL-1beta mRNA expression. Furthermore, bevacizumab lowered tumor extracellular fluid volume, plasma protein leakage from tumor vessels, the number of CD31-positive structures and tumor P(IF). The tumor plasma volume and the number of alpha-smooth muscle actin-positive vessels, however, remained unchanged. Our data suggest that carcinoma cell-derived VEGF either directly or indirectly participates in maintaining an inflammatory microenvironment in experimental KAT-4 carcinoma. Furthermore, our data indicate that the reduction of inflammation resulting in reduced vascular permeability and decrease in the tumor extracellular fluid volume by bevacizumab contributes to reduced tumor P(IF).     

Bevacizumab in the treatment of breast cancer: rationale and current data

Vascular endothelial growth factor (VEGF) has emerged as a key target for the treatment of cancer. As the ligand to the VEGF receptor, it plays a central role in promoting tumor angiogenesis. Overexpression of VEGF leads to poor outcomes in patients with breast cancer and other tumors. Preclinical studies have shown that the humanized monoclonal antibody to VEGF, bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA), can reduce tumor angiogenesis and inhibit the growth of solid tumors, either alone or in combination with chemotherapy. As a single agent or added to vinorelbine, bevacizumab has produced encouraging results in phase II clinical trials in patients with refractory metastatic breast cancer. When added to capecitabine chemotherapy in a phase III trial, bevacizumab produced a greater response rate, but did not prolong progression-free survival. This may reflect the late disease stage and poor prognostic factors in the patient population. A large, ongoing, phase III, cooperative group trial is evaluating the effect of bevacizumab in combination with paclitaxel as first-line therapy for metastatic disease. The adverse effect profile of bevacizumab differs from that of cytotoxic chemotherapy and includes hypertension, proteinuria, thrombosis, and epistaxis.     

Anti-tumor effects of bevacizumab in combination with paclitaxel on head and neck squamous cell carcinoma

Human tumors are dependent on angiogenesis for growth, and the vascular endothelial growth factor (VEGF) is a major regulator of this process. Bevacizumab (Avastin), a monoclonal antibody directed against VEGF, has shown promise in treating a variety of cancers. In this study, we first examined the anti-tumor effects of bevacizumab on head and neck squamous cell carcinoma (HNSCC). Then we examined the effects of bevacizumab combined with paclitaxel, a chemotherapeutic agent, in HNSCC. This is the first demonstration of the anti-tumor effects of bevacizumab on HNSCC. In vitro, bevacizumab did not show any antiproliferative effects against the HNSCC cell lines. However, in vivo, bevacizumab showed dramatic anti-tumor effects against HNSCC tumor xenografts in mice. In addition, treatment with a bevacizumab-paclitaxel combination resulted in a remarkable inhibition of the HNSCC tumor xenografts, compared to the effects of each agent separately. A decreased blood vessel density and an increased apoptotic index were seen in the shrunken tumors. These results suggest that bevacizumab in combination with paclitaxel could have useful clinical application in HNSCC.