Inhibition of angiogenesis and vascular leakiness by angiopoietin-related protein 4

Angiopoietins and angiopoietin-related proteins (ARPs) have been shown to regulate angiogenesis, a process essential for various neovascular diseases including tumors. Here, we identify ARP4/fasting-induced adipose factor/peroxisome proliferator-activated receptor gamma angiopoietin-related as a novel antiangiogenic modulatory factor. We hypothesized that ARP4 may regulate angiogenesis. In vitro experiments using purified recombinant ARP4 protein revealed that ARP4 markedly inhibited the proliferation, chemotaxis, and tubule formation of endothelial cells. Moreover, using corneal neovascularization and Miles permeability assays, we found that both vascular endothelial growth factor-induced in vivo angiogenesis and vascular leakiness were significantly inhibited by the addition of ARP4. Finally, we found remarkable suppression of tumor growth within the dermal layer associated with decreased numbers of invading blood vessels in transgenic mice that express ARP4 in the skin driven by the keratinocyte promoter. These findings demonstrate that ARP4 functions as a novel antiangiogenic modulatory factor and indicate a potential therapeutic effect of ARP4 in neoplastic diseases.     

肺腺癌肿瘤相关巨噬细胞的表达及与肿瘤血管生成的关系

目的:研究肺腺癌(Pulmonary adenocarcinoma)组织中肿瘤相关巨噬细胞(tumor-associated macro-phages,TAMs)的表达与临床病理学特征的关系及对肿瘤血管生成的影响。方法:应用免疫组化S-P法检测49例肺腺癌组织中TAMs、微血管密度(microvessel density,MVD)、血管内皮细胞因子(vascular endothelialgrowth factor,VEGF)的分布,并用计算机图像分析系统进行分析。结果:TAMs定量与淋巴结转移密切相关(P<0.01);与TNM分期有显著相关性(P<0.05)。肿瘤组织中MVD及VEGF表达高于对照组(P<0.05)。TAMs分布与MVD及VEGF呈正相关(r=0.56,P<0.05;r=0.58,P<0.05),VEGF表达与MVD呈显著正相关(r=0.334,P<0.01)。结论:TAMs表达可能与肿瘤血管生成有关,且影响肿瘤的生物学行为。     

Inhibition of growth factor-induced Ras signaling in vascular endothelial cells and angiogenesis by 3,3'-diindolylmethane

3,3'-Diindolylmethane (DIM), an indole derivative produced on consumption of broccoli and other cruciferous vegetables, has been shown to have multiple anticancer effects in both in vivo and in vitro models. The present study was carried out to clarify the mechanism of DIM's antiangiogenic activity. We found that DIM can inhibit vascular endothelial growth factor (VEGF)-induced cell proliferation and DNA synthesis in human umbilical vascular endothelial cells (HUVECs). Consistent with this inhibition, VEGF-induced extracellular signal-regulated kinase (ERK1/2) phosphorylation was greatly reduced. However, VEGF receptor phosphorylation induced by VEGF was not affected by DIM, indicating that DIM does not exert a direct and specific effect on the tyrosine kinase activity of this receptor. Further studies showed that DIM had a similar inhibitory effect on ERK1/2 phosphorylation induced by a variety of growth factors. Furthermore, Ras-GTP content, which dramatically increased after HUVECs were challenged by either individual growth factors or serum, was reduced by approximately 80% with 25 muM DIM treatment, which in turn resulted in the reduced activities of Raf and MEK, culminating in the drop of ERK1/2 activation. Overexpression of constitutively active GTPase mutant, Ras G12V, in HUVECs reversed the inhibitory effect of DIM on ERK1/2 activation. In a rodent Matrigel plug model, the presence of DIM strongly reduced VEGF-induced neovascularization, indicating that DIM is active in vivo. These data provide evidence that DIM inhibits Ras signaling induced by VEGF and other growth factors, which interferes with its downstream biological effects necessary for angiogenesis.     

Inhibition of tumor angiogenesis by a single-chain antibody directed against vascular endothelial growth factor

Monoclonal antibody (Ab) directed against the vascular endothelial growth factor, one of the major inducers of angiogenesis, can inhibit tumor growth in mice. Treatment of cancer patients with monoclonal Ab requires large-scale production of the clean Ab and frequent application of the Ab. This might be improved by using single-chain Ab fragments (scFvs), which can be produced in large quantities in bacteria and are attractive for gene therapeutic approaches. Here we describe anti-vascular endothelial growth factor scFvs derived from a human phage-display library able to block the vascularization of the chorioallantoic membrane of chick embryos and reduce the growth of s.c. tumors in nude mice. This work opens the way to develop gene therapy-based strategies using a scFv to treat angiogenesis-dependent diseases.     

Inhibition of angiogenesis by suramin.

In this study, we have determined the ability of suramin to inhibit angiogenesis in the chick chorioallantoic membrane. Suramin alone showed significant angiostatic activity in a dose-related manner. Suramin also potentiated the activity of the angiostatic steroids, cortisol-21-phosphate, 17 alpha-hydroxyprogesterone, tetrahydrocortisol, and tetrahydrocortexolone. The presence of heparin decreased the angiostatic activity of suramin. These results suggest that suramin may decrease tumor growth by inhibiting angiogenesis. These novel findings indicate that suramin, perhaps in combination with angiostatic steroids, may be the basis for important new therapeutic approaches for diseases of neovascularization.     

Inhibition of renal cell carcinoma angiogenesis and growth by antisense oligonucleotides targeting vascular endothelial growth factor

Angiogenesis is critical for growth and metastatic spread of solid tumours. It is tightly controlled by specific regulatory factors. Vascular endothelial growth factor has been implicated as the key factor in tumour angiogenesis. In the present studies we evaluated the effects of blocking vascular endothelial growth factor production by antisense phosphorothioate oligodeoxynucleotides on the growth and angiogenic activity of a pre-clinical model of renal cell carcinoma (Caki-1). In vitro studies showed that treating Caki-1 cells with antisense phosphorothioate oligodeoxynucleotides directed against vascular endothelial growth factor mRNA led to a reduction in expressed vascular endothelial growth factor levels sufficient to impair the proliferation and migration of co-cultured endothelial cells. The observed effects were antisense sequence specific, dose dependent, and could be achieved at a low, non-toxic concentration of phosphorothioate oligodeoxynucleotides. When vascular endothelial growth factor antisense treated Caki-1 cells were injected into nude mice and evaluated for their angiogenic potential, the number of vessels initiated were approximately half that induced by untreated Caki-1 cells. To test the anti-tumour efficacy of vascular endothelial growth factor antisense, phosphorothioate oligodeoxynucleotides were administrated to nude mice bearing macroscopic Caki-1 xenografts. The results showed that the systemic administration of two doses of vascular endothelial growth factor antisense phosphorothioate oligodeoxynucleotides given 1 and 4 days after the tumours reached a size of approximately 200 mm(3) significantly increased the time for tumours to grow to 1000 mm(3).     

Inhibition of endothelial cell migration and angiogenesis by a vascular endothelial growth factor receptor-1 derived peptide

Vascular endothelial growth factor receptor-1 (VEGFR-1) exists in two isoforms: a membrane-bound isoform (mVEGFR-1) and a soluble one (sVEGFR-1). mVEGFR-1 is involved in endothelial cell migration and survival supported by VEGF-A and placenta growth factor (PlGF), whereas the biologic function of sVEGFR-1 has not been fully elucidated. We previously reported that sVEGFR-1 induces endothelial cell motility and promotes endothelial cell adhesion. In this study, we tested a set of VEGFR-1-derived peptides for their ability to interfere with endothelial cell migration. Peptide B3 was found to specifically inhibit cell migration induced by sVEGFR-1 and by mVEGFR-1-specific ligands. Moreover, peptide B3 markedly hampered angiogenesis in vitro and in vivo and was found to interfere with VEGFR-1 homodimerisation. Altogether, these data demonstrate that peptide B3 might be a useful tool for the specific inhibition of VEGFR-1 function and might represent a basis for the development of new anti-angiogenic compounds.     

Inhibition of neuroblastoma-induced angiogenesis by fenretinide.

Retinoids are a class of natural or synthetic compounds that participate in the control of cell proliferation, differentiation and fetal development. The synthetic retinoid fenretinide (HPR) inhibits carcinogenesis in various animal models. Retinoids have also been suggested to be effective inhibitors of angiogenesis. The effects of HPR on certain endothelial cell functions were investigated in vitro, and its effects on angiogenesis was studied in vivo, by using the chorioallantoic membrane (CAM) assay. HPR inhibited vascular endothelial growth factor- (VEGF-) and fibroblast growth factor-2- (FGF-2)-induced endothelial cell proliferation without affecting endothelial motility; moreover, HPR inhibited growth factor-induced angiogenesis in the CAM assay. Furthermore, a significant antiangiogenic potential of HPR has also been observed in neuroblastoma (NB) biopsy-induced angiogenesis in vivo. We previously demonstrated that supernatants derived from NB cell lines stimulated endothelial cell proliferation. In the present study, we found that this effect was abolished when NB cells were incubated in the presence of HPR. VEGF- and FGF-2-specific ELISA assays, performed on both NB cells derived from conditioned medium and cellular extracts, indicated no consistent effect of HPR on the level of these angiogenic cytokines. Moreover, RT-PCR analysis of VEGF and FGF-2 gene expression confirmed the above lack of effect. HPR was also able to significantly repress the spontaneous growth of endothelial cells, requiring at least 48-72 hr of treatment with HPR, followed by a progressive accumulation of cells in G(1) at subsequent time points. Finally, immunohistochemistry experiments performed in the CAM assay demonstrated that endothelial staining of both VEGF receptor 2 and FGF-2 receptor-2 was reduced after implantation of HPR-loaded sponges, as compared to control CAMs. These data suggest that HPR exerts its antiangiogenic activity through both a direct effect on endothelial cell proliferative activity and an inhibitory effect on the responsivity of the endothelial cells to the proliferative stimuli mediated by angiogenic growth factors.     

Inhibition of vascular endothelial growth-factor induced cell-growth by an angiogenesis inhibitor agm-1470 in capillary endothelial-cells

It is known that an anti-angiogenic compound AGM-1470 inhibits cells in vitro and in vivo, on mitogen-induced cell growth in capillary endothelial cells. In monolayer cultures, 1 ng/ml AGM-1470 completely inhibited both basic fibroblast growth factor (bFGF) induced cell growth and vascular endothelial growth factor (VEGF) induced cell growth in a cytostatic manner. IC50 was 85 pg/ml and 55 pg/ml for bFGF and VEGF induced cell growth, respectively. Moreover, in collagen gels, AGM-1470 suppressed the colony formation induced by bFGF and by VEGF in a dose dependent manner. Few colonies appeared 25 days after co-culuture with I ng/ml AGM-1470 and either 1 ng/ml bFGF or 5 ng/ml VEGF. It is suggested that a potent; inhibition of growth signals of more than one growth factor for endothelial cells might be involved in anti-angiogenic activity of AGM-1470.     

Inhibition of tumor cell invasion and angiogenesis by motuporamines

Tissue invasion is an important determinant of angiogenesis and metastasis and constitutes an attractive target for cancer therapy. We have developed an assay to identify agents that inhibit invasion by mechanisms other than inhibition of cell attachment or cytotoxicity. A screen of marine sponge extracts identified motuporamines as micromolar inhibitors of invasion of basement membrane gels by MDA-231 breast carcinoma, PC-3 prostate carcinoma, and U-87 and U-251 glioma cells. Motuporamine C inhibits cell migration in monolayer cultures and impairs actin-mediated membrane ruffling at the leading edge of lamellae. Motuporamine C also reduces beta1-integrin activation, raising the possibility that it interferes with "inside-out" signaling to integrins. In addition, motuporamine C inhibits angiogenesis in an in vitro sprouting assay with human endothelial cells and an in vivo chick chorioallantoic membrane assay. The motuporamines show little or no toxicity or inhibition of cell proliferation, and they are structurally simple and easy to synthesize, making them attractive drug candidates.     

血管内皮生长因子及其受体双靶向阻断对膀胱癌细胞生长及血管生成的抑制作用

目的 探讨血管内皮生长因子(VEGF)及其受体(KDR)双靶向阻断对人膀胱癌T24细胞和裸鼠膀胱癌移植瘤生长的抑制作用.方法 构建VEGF siRNA和可溶性KDR(sKDR)表达质粒的共转染细胞系,采用二苯基溴化四氮唑蓝(MTT)法和流式细胞仪测定T24细胞的增殖和凋亡,采用免疫组化法检测裸鼠移植瘤组织中VEGF的表达、瘤间质微血管密度(MVD)和细胞DNA拓扑异构酶(Topo)Ⅱα的表达,采用原位末端标记(TUNEL)法检测裸鼠移植瘤中肿瘤细胞的凋亡.结果 MTT法检测结果显示,VEGF siRNA、sKDR和联合应用组细胞的生存率分别为56.3%±8.3%、42.6%±13.8%和32.5%±4.3%,均明显低于阴性对照组(97.3%±11.6%,P＜0.0001).流式细胞仪分析显示,VEGF siRNA、sKDR和联合应用组在G.期前均出现亚二倍体凋亡峰,凋亡率分别为5.1%±0.9%、4.2%±0.5%和8.8%±0.7%,均高于阴性对照组(0.9%±0.4%,P＜0.05),而且联合应用组的凋亡率还明显高于VEGF siRNA和sKDR组(P＜0.01).体内实验结果显示,VEGF siRNA、sKDR和联合应用组的肿瘤生长均受到不同程度的抑制,联合应用组从16 d开始肿瘤体积即明显小于阴性对照组(P＜0.05),28 d起肿瘤生长几乎处于停滞状态.免疫组化分析显示,联合应用组肿瘤组织中VEGF的表达水平为54.37±5.28,显著低于阴性对照组(141.66±8.59,P＜0.0001);瘤间质MVD仅为8.22±3.79,明显低于阴性对照组(61.76±5.28,P＜0.0001)和sKDR组(19.46±4.16,P=0.0089);瘤细胞增殖指数为1.5%±0.7%,显著低于阴性对照组(11.8%±5.2%,P＜0.0001);而凋亡率达到67.2%±8.5%,明显高于阴性对照组(8.7%±2.7%,P＜0.0001)、VEGF siRNA组(54.3%±4.8%,P=0.0492)和sKDR组(52.3%±6.4%,P=0.0293).结论 VEGF siRNA与sKDR单独应用均可不同程度地抑制肿瘤细胞增殖并诱导细胞凋亡,但二者联合应用时靶向双位点的治疗效果更为显著.     

Inhibition of tumor angiogenesis by hexuronyl hexosaminoglycan sulfate

The efficacy of heparin (HEP), the heparin analogue hexuronyl hexosaminoglycan sulfate (HHS), and hydrocortisone (HC) was studied in inhibiting the growth of four morphologically distinct pancreatic adenocarcinoma lines (CBP, LHP2, LSP3, and Pour-LVG) in hamsters. Animals were inoculated with LD100 doses of one of the four tumor lines and were randomly allocated to groups of five animals, which received in their drinking water either: HEP (1000 U/ml) alone, HHS (10 mg/ml) alone, HC (0.5 mg/ml) alone, HEP plus HC, HHS plus HC, or no additives (control). Tumors were measured, growth rates calculated, and nonparametric statistical comparisons made among the median growth rates of all of the treatment groups. All four tumors were tested in the rabbit cornea assay for their ability to induce angiogenesis. Extracts of tumors from control animals as well as from animals treated with HHS plus HC were prepared for quantitative testing in vitro by endothelial cell migration assay. All four tumor lines caused angiogenesis as measured in the rabbit cornea assay. A reduction in median tumor growth rates was observed in animals treated with HHS plus HC bearing the CBP, Pour-LVG, and LSP3 tumors. Similarly, in vitro capillary endothelial cell migration was decreased by HHS plus HC treatment in animals bearing CBP, Pour-LVG, and LSP3 tumors. Animals bearing the LHP2 tumor showed no effect of HHS plus HC treatment on tumor growth rate and no effect on endothelial cell migration. HEP alone, HHS alone, HC alone, and HEP plus HC showed no effect on tumor growth rate in any of the four tumors tested.     

Inhibition of angiogenesis by extracellular protein kinase A

The cyclic-AMP dependent protein kinase (PKA) signaling pathway regulates cell growth, development, metabolism, and gene expression. Peripheral blood of cancer patients but not normal individuals, shows increased catalytic subunit levels of PKA (PKAc). We showed here that this extracellular form of PKAc (ECPKA) from conditioned media of cultured cancer cells as well as purified PKAc inhibit angiogenesis, using the in utero chicken embryo chorioallantoic membrane assay. Inhibition of angiogenesis is partially reversed by PKI, a peptide inhibitor of PKA, thus suggesting an anti-angiogenic role for ECPKA. The significance of ECPKA in cancer is discussed.     

Inhibition of angiogenesis.

The concept of antiangiogenic therapy was first proposed in the early 1970s as a method of restricting tumor growth by inhibiting angiogenesis. In subsequent years sufficient knowledge about the process of angiogenesis itself was obtained so that it is now possible to begin to develop antiangiogenic therapy for clinical use. At least three strategies are feasible: (i) inhibition of release of angiogenic molecules from tumor cells; (ii) neutralization of angiogenic molecules that have already been released; and (iii) inhibition of vascular endothelial cells from responding to angiogenic stimulation. Most of the angiogenic inhibitors that have been discovered at the time of writing, directly interfere with the ability of endothelial cells to form new capillary blood vessels. Antiangiogenic activity is a newly found property of alpha-interferon. Although alpha-interferon is a relatively weak angiogenesis inhibitor in comparison to others, it has been very successful in the treatment of life-threatening hemangiomas in children. Early clinical experience with this first angiogenesis inhibitor to reach clinical trial, indicates that optimal antiangiogenic therapy in the future is likely to be based on the long-term use of inhibitors with low toxicity, and with little chance of inducing drug-resistance. It is apparent that different types of angiogenesis inhibitor may be administered together and that these compounds may also be administered to cancer patients as adjuncts to conventional chemotherapy. It is important to recognize that tumor vasculature has other properties besides angiogenesis, which make it a potential specific target for anti-cancer therapy.     

Inhibition of angiogenesis by salmosin expressed in vitro

Recently, salmosin, a novel snake venom-derived disintegrin containing the Arg-Gly-Asp (RGD) sequence, was reported to be both antiangiogenic and antitumorigenic. The antitumor activity was substantiated by in vivo administration of recombinant salmosin into mice bearing tumors. However, it was difficult to prepare functionally active recombinant salmosin and to maintain a therapeutically effective concentration of the protein in the circulatory system by daily injections. Hence, we have suggested that salmosin gene transfer mediated by cationic liposomes may be a practical alternative for cancer treatment. Plasmids encoding the salmosin gene were constructed and then transferred by means of cationic liposomes into transformed human embryonic kidney (HEK) 293 cells. The transfected genes were able to produce functionally active salmosin proteins in vitro. In fact, the expressed salmosin remarkably inhibited proliferation of bovine capillary endothelial (BCE) cells and effectively inhibited the migration of highly metastatic B16BL6 mouse melanoma cells. Neovascularization in chick chorio-allantoic membranes (CAM) and in Matrigel implanted subcutaneously into mice was greatly inhibited in the presence of the expressed salmosin. Based on these experimental results, we suggest that the antitumor effect induced by salmosin gene transfection may be due to the antiangiogenic activity of the expressed salmosin proteins.     

Inhibition of tumor metastasis by sodium caffeate and its effect on angiogenesis

OBJECTIVE: Sodium caffeate (SC), the sodium salt of caffeic acid, was synthesized in our laboratory. We studied the antimetastatic effect induced by SC and its inhibition of tumor angiogenesis using various in vitro and in vivo metastasis assays. METHODS: The in vivo inhibitory effect of SC on metastasis and angiogenesis was examined in the Lewis lung carcinoma pulmonary metastasis model and chicken chorioallantoic membrane (CAM) model, respectively. MTT assay and flow cytometry were used to measure the inhibition by SC of the proliferation of transformed human umbilical vein endothelial cells (ECV304) and the apoptosis induced by SC in ECV304 cells, respectively. A cell attachment assay was used to evaluate inhibition by SC of the adhesion activity of human high metastatic giant cell carcinoma of the lung (PG) cells. A cell invasion assay was used to evaluate the effect of SC on the ability of PG cells to cross tissue barriers. Inhibition by SC of gelatinase secretion in PG cells was determined by zymography. RESULTS: In vivo results showed that SC (1 g/kg i.p. for 14 days) inhibited pulmonary metastasis at a rate of 55%. There were no differences in animal weights among the groups. The angiogenesis of CAM was inhibited by SC (200 microg/egg) at a rate of 70%. In vitro studies showed that SC inhibited the proliferation of ECV304 cells by inducing apoptosis. SC also reduced the adhesion and invasion ability of PG cells and inhibited the secretion of MMP-2 and MMP-9 in PG cells. CONCLUSION: SC might be a potential antimetastatic agent with an antiangiogenic effect.     

Inhibition of heparanase activity and heparanase-induced angiogenesis by suramin analogues

Heparanase, a heparan sulfate-specific endo-beta-D-glucuronidase, plays an important role in tumor cell metastasis through the degradation of extracellular matrix heparan sulfate proteoglycans (ECM HSPG). Heparanase activity correlates with the metastatic propensity of tumor cells. Suramin, a polysulfonated naphthylurea, is an inhibitor of heparanase with suramin analogues shown to possess antiangiogenic and antiproliferative properties. We investigated the effects of selected suramin analogues (NF 127, NF 145 and NF 171) on heparanase activity and heparanase-driven angiogenesis. Studies of the ability of cellular extracts and purified heparanase from human, highly invasive and brain-metastatic melanoma (70W) cells revealed that heparanase expressed by these cells was effectively inhibited by suramin analogues in a dose-dependent manner. These analogues possessed more potent heparanase inhibitory activities than suramin: The concentrations required for 50% heparanase inhibition (IC(50)) were 20-30 microM, or at least 2 times lower than that for suramin. One hundred percent inhibition was observed at concentrations of 100 microM and higher. Of relevance, these compounds significantly decreased (i) the invasive capacity of human 70W cells by chemoinvasion assays performed with filters coated with purified HSPG or Matrigel trade mark, and (ii) blood vessel formation by in vivo angiogenic assays, thus linking their antiangiogenic properties with impedance of heparanase-induced angiogenesis. Specifically, inhibition of invasion by NF 127, NF 145 and NF 171 was found at 10 microM concentrations of compounds with a significant decrease of invasive values at concentrations as low as 1.5 microM. In addition, NF 127, NF 145 and NF 171 promoted nearly complete inhibition of heparanase-induced angiogenesis at values ranging from 236 microM (for NF 145) to 362 microM (for NF 127). These results further emphasize the importance of heparanase in invasive and angiogenic mechanisms and the potential clinical application of heparanase inhibitors such as suramin analogues in cancers and angiogenesis-dependent diseases.     

Inhibition of tumor growth and angiogenesis by soluble EphB4

EphB receptors and their ephrinB ligands play a key role in the formation of a regular vascular system. Recent studies have also shown the involvement of Eph/ephrin interactions in malignant tumor progression and angiogenesis. We have generated soluble monomeric EphB4 (sEphB4)-expressing A375 melanoma cells to study the effect of dominant negatively acting sEphB4 on tumor growth and angiogenesis. Soluble EphB4-expressing A375 tumors grown subcutaneously in nude mice show dramatically reduced tumor growth compared to control tumors. The proliferative capacity of sEphB4-expressing cells in monolayer culture is not altered. Yet, sEphB4-expressing A375 cells cannot establish proper cell-cell contacts in three-dimensional spheroids. However, sEphB4 transfectants have reduced proliferation and apoptosis rates when grown in three-dimensional culture in vitro or in subcutaneous tumors in vivo. Analysis of the vascular phenotype of the tumors revealed a reduction of intratumoral microvessel density in sEphB4-expressing tumors. Corresponding to these mouse experiments, a matched pair analysis of EphB4 and ephrinB2 expression in human colon carcinomas revealed significantly upregulated levels of EphB4 expression compared to adjacent normal tissue. Taken together, the data identify dual effects of sEphB4 on the tumor and the vascular compartment that collectively inhibit tumor growth.     

Inhibition of K562 leukemia angiogenesis and growth by expression of antisense vascular endothelial growth factor (VEGF) sequence

Vascular endothelial growth factor (VEGF), a major angiogenic factor, plays a key role in the growth of solid tumor. Recently, expression of VEGF and its receptors has been found on leukemic cells as well as on endothelial cells. VEGF may fulfill a fundamental role in promoting tumor angiogenesis and proliferation by stimulating both endothelial cells and leukemic cells. To investigate the role of VEGF in the angiogenesis and growth of leukemic cell, we used an antisense strategy to downregulate VEGF expression in K562 cells, a human erythroleukemia cell line. Expression of antisense-VEGF in K562 cells reduced the secretion of VEGF protein and inhibited cell survival. The proliferation and migration of human umbilical vein endothelial cells were decreased in response to the conditioned medium (CM) from K562 cells expressed antisense-VEGF, compared to CM from K562 cells transfected with vector control. Moreover, subcutaneous injection of nude mice with antisense-VEGF K562 cells inhibited tumor growth with a reduction of the density of microvessels and an increased apoptosis in those tumors, compared to vector control K562 cells. These results suggest that the efficient downregulation of the VEGF production in leukemic cells using antisense-VEGF may constitute a novel strategy of treatment in leukemia.     

iNOS反义寡核苷酸对肿瘤血管生成抑制的研究

目的:探讨诱导型一氧化氮合成酶(induciblenitricoxidesynthase,iNOS)的反义寡核苷酸对肿瘤血管生成的抑制作用。方法:将人工合成的互补于iNOS基因翻译起始部位的反义-寡核苷酸(AS-ODN)及其错义-寡核苷酸(Mis-ODN)经脂质体介导转染入A549细胞后,了解其产生一氧化氮(nitricoxide,NO)的能力;将AS-ODN及其错义序列、空白对照分别在第1、4、7、12和18天注入接种有A549肺腺癌细胞的裸鼠的腹腔中,于第21天检测小鼠体内肿瘤的大小、肿瘤内血管密度(microvesseldensity,MVD)和肿瘤组织血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)表达的情况。结果:体外实验显示,iNOS的AS-ODN组和对照组相比,对A549细胞产生NO的抑制能力较强,并呈时间和剂量依赖性。在动物实验中,iNOS的AS-ODN对肿瘤的抑制作用较Mis-ODN和空白序列为强,差异均有统计学意义,F值分别为3·24和3·89,P值分别为0·044和0·032;AS-ODN组、Mis-ODN组及空白对照组中MVD的平均值分别为6·9±3·2、11·8±6·8和12·9±5·4,AS-ODN组MVD较Mis-ODN组和空白组明显降低,差异均有统计学意义,F值分别为5·53和7·63,P值分别为0·006和0·001;同时其VEGF的表达阳性率较Mis-ODN组明显下降,u=-2·457,P=0·017。结论:iN-OS的AS-ODN可降低肿瘤细胞产生NO的能力,在动物体内可降低肿瘤VEGF的表达和新生血管的生成,抑制肿瘤的生长。