Inhibition Of Tumor-induced Angiogenesis Research Articles

Macrolide Antibiotics By Modulating the Autophagic Flux Exert an Antileukemic Effect through the Involvement of hERG1 Potassium Channel

Macrolide Antibiotics (MAs) have been recently shown to exert an antineoplastic activity in different types of cancers, including hematologic malignancies alone or in combination with either chemotherapeutic drugs or tyrosine kinase inhibitors. How MAs can exert an antineoplastic activity is still under investigation and different mechanisms have been proposed, such as inhibition of late phase autophagy, induction of apoptosis, inhibition of tumor-induced angiogenesis, reactive oxygen species production, reduction of mitochondrial biogenesis and inhibition of P-glycoprotein (PgP). MAs are also known to block cardiac hERG1 currents and for this reason can cause QT prolongation. Among MAs antibiotics, erythromycin (Er) and clarithromycin (Cla) have no particularly harmful side effects, have a low risk of TdP and in fact are in clinical use by many years. In addition, it was recently reported that the concomitant administration of Er may provide a reduction in cardiac liability of potent hERG1-blocking drugs due to the occupancy by Er of the external site that reduces the affinity of hERG1 blockers for their specific binding site inside the pore region of the channel. We have provided several evidences that hERG1 channels are often aberrantly expressed in human cancers including leukemias and two conductive isoforms of the channel have been identified so far, hERG1A and hERG1B, the latter prevailing in leukemias. hERG1 blockade exerts an antileukemic effect in vitro and in vivo in preclinical models. In acute myeloid leukemias (AML), hERG1 mediates the FLT-1-dependent cell migration and invasion hence conferring a greater malignancy, while in acute lymphoblastic leukemia (ALL), hERG1 channels modulate pro-survival signals triggered by bone marrow stromal cells (MSC) in the bone marrow microenvironment and the block of hERG1 activity overcomes chemoresistance. MAs are also known to inhibit hERG1 currents, which, conversely, are emerging as regulators of leukemia cell survival and chemoresistance. We analyzed the role of hERG1 on the MAs-induced effects on AL, providing evidence that (1) both hERG1 blockade and silencing modulate autophagy, triggering autophagic and apoptotic cell death, similarly to MAs; (2) MAs block hERG1-sustained currents in AL and (3) the effects of MAs depend on hERG1 inhibition. We tested the activity of a panel of MAs on acute leukemias (AL), both myeloid and lymphoid, alone and in combination with chemotherapeutic agents commonly used for AL treatment. MA's effects were tested both in vitro and in preclinical mouse models. We provide evidence that MAs in AL (1) have an antileukemic effect; (2) modulate autophagy, triggering it and then blocking the autophagic flux; (3) affect intracellular signaling pathways, in turn leading to both apoptotic and autophagic cell death. Overall we propose to include MAs in the treatment schedule of ALs, especially for chemoresistant forms. DisclosuresNo relevant conflicts of interest to declare.

Pleiotropic effects of bisphosphonates on osteosarcoma

Osteosarcoma is the most common primary malignant tumor of bone and accounts for half of all primary skeletal malignancies in children and teenagers. The prognosis for patients who fail or progress on first-line chemotherapy protocols is poor, therefore, additional adjuvant therapeutic strategies are needed. A recent feasibility study has demonstrated that the nitrogen-containing bisphosphonate zoledronic acid (ZOL) can be combined safely with conventional chemotherapy. However, the pharmacodynamics of bisphosphonate therapy is not well characterized. Osteosarcoma is a highly angiogenic tumor. Recent reports of the anti-angiogenic effects of bisphosphonates prompted us to determine whether nitrogen-containing bisphosphonate (ZOL and alendronate) treatment attenuates osteosarcoma growth by inhibition of osteoclast activity, tumor-mediated angiogenesis, or direct inhibitory effects on osteosarcoma. Here, we demonstrate that bisphosphonates directly inhibit VEGFR2 expression in endothelial cells, as well as endothelial cell proliferation and migration. Additionally, bisphosphonates also decrease VEGF-A expression in osteosarcoma (K7M3) cells, resulting in reduced stimulation of endothelial cell migration in co-culture assays. ZOL also decreases VEGFR1 expression in aggressive osteosarcoma cell lines (K7M3, 143B) and induces apoptosis of these cells, but has negligible effects on less aggressive osteosarcoma cell lines (K12 and TE85). In vivo ZOL treatment results in significant reduction in osteosarcoma-initiated angiogenesis and tumor growth in a murine model of osteosarcoma. In conclusion, bisphosphonates have diverse growth inhibitory effects on osteosarcoma through: (1) activation of apoptosis and inhibition of cell proliferation, (2) inhibition of VEGF-A and VEGFR1 expression by tumor cells, (3) inhibition of tumor-induced angiogenesis, and (4) direct inhibitory actions on endothelial cells.

Ganoderma lucidum: A Potential for Biotechnological Production of Anti-Cancer and Immunomodulatory Drugs

Based on the analysis of more than 270 patents and scientific articles, this state-of-the-art review presents Ganoderma lucidum, a medicinal basidiomycete mushroom with immunomodulatory and anti-cancer effects. Cultivation methods for the commercial production of G. lucidum fruit bodies and mycelia are summarized, with main active compounds of triterpenoids, polysaccharides, and proteins, often found in forms of proteoglycans or glycopeptides. Pharmacological effects with emphasis on anti-cancer and immunomodulatory functions are presented, separately for spores and dry mycelia, and for the groups of triterpenoids, polysaccharides, proteins and glycoproteins. Patents disclosing preparation methods of extracts and purified pharmaceutical isolates are reviewed, and examples of anti-cancer formulations, used as pharmaceuticals or nutraceuticals, are given. The review suggests that according to the present understanding, the anti-cancer activity of G. lucidum may be attributed to at least five groups of mechanisms: (1) activation/modulation of the immune response of the host, (2) direct cytotoxicity to cancer cells, (3) inhibition of tumor-induced angiogenesis, (4) inhibition of cancer cells proliferation and invasive metastasis behaviour, and (5) carcinogens deactivation with protection of cells. Although, the data from recent in vitro and in vivo studies demonstrate promising anti-cancer effects, a need is identified for further (1) isolation and purification of compounds, with deeper understanding of their individual and synergistic pharmacological effects, (2) molecular level studies of the antitumor and immuno-supportive mechanisms, (3) well designed in vivo tests and controlled clinical studies, and (4) standardisation and quality control for G. lucidum strains, cultivation processes, extracts and commercial formulations.

Cetuximab: still an option in the treatment of pancreatic cancer?

Introduction: In this review, we analyzed the current literature about cetuximab to clarify its role in the treatment of pancreatic cancer. Using single-agent gemcitabine has been the standard treatment for more than 15 years for advanced pancreatic cancer. The attempts at improving the results by combining it with several other drugs, such as fluorouracil, cisplatin, irinotecan, oxaliplatin, or pemetrexed produced no clear survival benefit. Recently, however, new combination chemotherapy regimens (e.g., FOLFIRINOX, nab-paclitaxel plus gemcitabine) achieved a significant survival benefit compared to gemcitabine alone.Areas covered: Epidermal growth factor receptor (EGFR) transmembrane glycoprotein has been demonstrated to be overexpressed in pancreatic cancer, and it correlates with more advanced disease, poor survival, and the presence of metastases. Therefore, inhibition of the EGFR signaling pathway could be an attractive therapeutic target in this tumor. Although several combinations of EGFR inhibitors with chemotherapy demonstrate inhibition of tumor-induced angiogenesis, tumor cell apoptosis, and regression in xenograft models, these benefits remain to be confirmed.Expert opinion: The encouraging results from preclinical and early clinical studies with cetuximab in pancreatic cancer were not confirmed in a Phase III trial. Cetuximab failed to demonstrate improved patient outcome when paired with various chemotherapeutic regimens and/or other biological agents.

P14ARF inhibits human glioblastoma–induced angiogenesis by upregulating the expression of TIMP3

Malignant gliomas are the most common and the most lethal primary brain tumors in adults. Among malignant gliomas, 60%-80% show loss of P14ARF tumor suppressor activity due to somatic alterations of the INK4A/ARF genetic locus. The tumor suppressor activity of P14ARF is in part a result of its ability to prevent the degradation of P53 by binding to and sequestering HDM2. However, the subsequent finding of P14ARF loss in conjunction with TP53 gene loss in some tumors suggests the protein may have other P53-independent tumor suppressor functions. Here, we report what we believe to be a novel tumor suppressor function for P14ARF as an inhibitor of tumor-induced angiogenesis. We found that P14ARF mediates antiangiogenic effects by upregulating expression of tissue inhibitor of metalloproteinase-3 (TIMP3) in a P53-independent fashion. Mechanistically, this regulation occurred at the gene transcription level and was controlled by HDM2-SP1 interplay, where P14ARF relieved a dominant negative interaction of HDM2 with SP1. P14ARF-induced expression of TIMP3 inhibited endothelial cell migration and vessel formation in response to angiogenic stimuli produced by cancer cells. The discovery of this angiogenesis regulatory pathway may provide new insights into P53-independent P14ARF tumor-suppressive mechanisms that have implications for the development of novel therapies directed at tumors and other diseases characterized by vascular pathology.

Inhibition of tumor-induced angiogenesis and its mechanism by ardipusilloside I purified from Ardisia pusilla

The aim of this study was to evaluate the effects of ardipusilloside I isolated from Ardisia pusilla on tumor angiogenesis and its mechanism of action. The anti-angiogenic effect in vivo was evaluated on xenograft in the athymic mice model and the chicken chorioallantoic membrane (CAM) neovascularization model, the inhibition of growth in vitro was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and the mechanism was demonstrated through detecting microvessel density (MVD), vascular endothelial growth factor (VEGF), VEGF receptor 2 (VEGFR2) and P-VEGFR2 protein expressions, as well as mRNA expressions of VEGF and VEGFR2. The results showed that ardipusilloside I had a good inhibitory effect on A549 xenografted tumor growth, angiogenesis of CAM, and A549 cell growth. Compared to the negative control, MVD protein and mRNA expressions of VEGF and VEGFR were significantly inhibited by ardipusilloside I in a dose-dependent manner. These findings suggested that ardipusilloside I might be a promising candidate as angiogenesis inhibitors.

Mesenchymal stem cells as vehicles for targeted delivery of anti‐angiogenic protein to solid tumors

Inhibition of tumor-induced angiogenesis may restrict tumor growth and metastasis. Long-term systemic delivery of angiogenic inhibitors is associated with toxicity, as well as other severe side-effects. The utility of cells as vehicles for gene therapy to deliver therapeutic molecules has been suggested to represent an efficient approach. Mesenchymal stem cells (MSCs) exhibit a tropism to cancer tissue, and may serve as a cellular delivery vehicle and a local producer of anti-angiogenic agents. In the present study, we attempted to assess production of the transgene, α1-antitrypsin (AAT), in lentivirus-transduced human MSCs and its cytotoxicity against human umbilical cord vein endothelial cells (HUVEC). The secreted protein from these effector cells was determined by an enzyme-linked immunosorbent assay. The cytotoxicity of hMSCs that overexpress the human AAT gene against HUVEC was evaluated with an apoptotic assay. Lentivirus-transduced hMSCs produced functional AAT and displayed much higher cytotoxicity against HUVEC than untransduced hMSCs. Moreover, AAT secreted from transduced hMSCs significantly inhibited HUVEC proliferation compared to untransduced hMSCs. The data obtained demonstrate for the first time that genetically modified hMSCs released abundant and functional AAT that caused obvious cytotoxicity to HUVEC. hMSC may serve as an effective platform for the targeted delivery of therapeutic proteins to cancer sites.

Expression of MASPIN and angiogenin in nasopharyngeal carcinoma: Novel preliminary clinico-pathological evidence

Conclusions: Further studies based on large series are necessary to investigate the role of MASPIN and angiogenin (ANG) in angiogenetic mechanisms of nasopharyngeal carcinoma (NPC) and their potential as prognostic markers. Objectives: NPC is a malignancy with an incidence among Caucasians of < 1 per 100 000 per year. In NPC, the aberrations of many pathways and the alteration in expression of several proteins have been reported. Tumor angiogenesis is the result of an imbalance between pro- and anti-angiogenic factors. MASPIN exerts several anti-tumor effects including inhibition of tumor-induced angiogenesis. ANG regulates angiogenesis under both physiological and pathological conditions supporting primary and metastatic tumor growth. Methods: For the first time, we preliminarily investigated by immunohistochemistry the subcellular localization and expression of MASPIN, and the expression of ANG (in both carcinoma cells and intra-tumor vessels) and Ki-67 in 15 Caucasian patients with NPC treated with the same chemo-radiotherapeutic protocol. Results: MASPIN-positive NPCs had a prevalent cytoplasmic localization pattern. A trend towards significant direct correlation between MASPIN presence and disease-free survival (DFS) (p = 0.08) and a trend towards significant inverse correlation between ANG expression and DFS (p = 0.07) were found. An association between MASPIN presence and lower ANG expression in carcinoma cells was disclosed (statistical trend, p = 0.10).

Anti-angiogenic and Anti-metastatic Effects of .BETA.-1,3-D-Glucan Purified from Hanabiratake, Sparassis crispa

Sparassis crispa (SC), Hanabiratake in Japanese, is an edible mushroom with medicinal properties, that contains more than 40% beta-D-glucan. It was concluded from results of the methylation study that beta-D-glucan from SC (SBG) was composed of a backbone of beta-(1-->3)-linked D-glucopyranosyl residues, and had beta-D-glucopyranosyl groups joined through O-6 and O-2 of D-glucose of the backbone. We purified SBG and investigated its anti-angiogenic functions and anti-metastatic effects on neoplasm using different animal models. The oral administration of the purified SBG suppressed B16-F10 cell-induced angiogenesis in the dorsal air sac assay using female ICR mice as well as vascular endothelial growth factor induced neovascularization in the Matrigel plug assay using female C57BL/6J mice. Furthermore, it suppressed the growth and numbers of the metastatic tumor foci in lung, along with the primary tumor growth in the spontaneous metastatic model using female C57BL/6J mice. From these results, it is apparent that the oral administration of SBG results in suppressive effect on tumor growth and metastasis in lung through the inhibition of tumor induced-angiogenesis. These effects are not a result of direct action on the endothelial cells because cell growth, migration and capillary-like tube formation were not affected in the human umbilical vein endothelial cells by SBG application. This is the first report showing that the oral administration of SBG is capable of suppressing angiogenesis and metastasis.

Anti-tumor actions of major component 3′- O-acetylhamaudol of Angelica japonica roots through dual actions, anti-angiogenesis and intestinal intraepithelial lymphocyte activation

We recently demonstrated that two chalcones isolated from Angelica keiskei roots have anti-tumor and anti-metastatic activities through the inhibition of tumor-induced angiogenesis, but the anti-tumor substances of Angelica japonica roots are unknown. We attempted to clarify the anti-tumor action and its mechanisms of a major component 3′- O-acetylhamaudol isolated from A. japonica roots. We first examined the effects of 3′- O-acetylhamaudol on tumor growth in colon 26-bearing mice. Furthermore, we examined the effects of 3′- O-acetylhamaudol on angiogenic factors (vascular endothelial growth factor receptor-2 (VEGFR-2) phosphorylation in human umbilical vein endothelial cells (HUVECs), and vascular endothelial growth factor (VEGF) production and hypoxia-inducible factor (HIF)-1α expression in tumors). 3′- O-Acetylhamaudol (25 and 50 mg/kg, twice daily) inhibited the tumor growth in colon 26-bearing mice. Although 3′- O-acetylhamudol had no effect on the VEGF production and HIF-1α in colon 26 cells, it (10 μM) inhibited the VEGF-induced angiogenesis and VEGF-induced VEGFR-2 phosphorylation in HUVECs. 3′- O-Acetylhamaudol has anti-tumor effects mediated through dual mechanisms, i.e., anti-angiogenic actions and the modulation of the immune system in the spleen and small intestine in tumor-bearing mice.

Discovery of N-phenyl nicotinamides as potent inhibitors of Kdr

Inhibition of tumor-induced angiogenesis is a promising strategy in anticancer research. Neovascularization is a process required for both tumor growth and metastasis. Enhanced understanding of the underlying molecular mechanisms has led to the discovery of a variety of pharmaceutically attractive targets. Decades of investigation suggest that vascular endothelial growth factor (VEGF) and its receptors, in particular VEGFR2 or kinase insert-domain-containing receptor (Kdr), play a critical role in the growth and survival of endothelial cells in newly forming vasculature. The clinical utility of inhibitors of this receptor tyrosine kinase is currently under intense investigation. Herein we report our efforts in this arena.

The retinoid X receptor-selective ligand, LGD1069, inhibits tumor-induced angiogenesis via suppression of VEGF in human non-small cell lung cancer

The present study determined the influence of a retinoid X receptor agonist LGD1069 on angiogenesis in non-small cell lung cancer. In A549 xenograft models, treatment with LGD1069 inhibited the growth and CD31 expression compared with control. In vivo angiogenesis assay utilizing hollow fiber, LGD1069 reduced density of capillary network induced by tumor cells. To determine the basis of these observations, we examined the expression of VEGF and activation of JNK and ERK in A549 cells exposed to LGD1069. Our data showed that LGD1069 decrease the VEGF expression of tumor cells in a dose-dependent manner. Furthermore, it was demonstrated that the decreasing expression of VEGF was consist with inhibition of JNK and ERK activation induced by LGD1069. Collectively, our results suggest a role of LGD1069 in treatment for non-small cell lung cancer by inhibition of tumor-induced angiogenesis.

Adeno-associated virus vector-mediated delivery of pigment epithelium-derived factor restricts neuroblastoma angiogenesis and growth

Purpose The purpose of this study was to evaluate the ability of adeno-associated virus (AAV) vector-mediated delivery of pigment epithelium-derived factor (PEDF) to inhibit neuroblastoma (NB) xenograft growth. Pigment epithelium-derived factor was chosen for this study because, in addition to being a potent inhibitor of angiogenesis, it is capable of inducing neuronal differentiation. Methods Cohorts of mice received either recombinant AAV encoding human PEDF (rAAV-hPEDF) at a range of doses or control vector via tail vein. Subsequent hPEDF expression was measured by enzyme-linked immunoassay. After 6 weeks, the mice were given human NB cells by retroperitoneal injection and then killed 5 weeks later. Tumor weight, microvessel density, tumor differentiation, apoptosis, and levels of intratumoral vascular endothelial growth factor (VEGF) expression were determined at that time. In subsequent cohorts of mice, AAV-mediated murine PEDF expression was tested against both human NB xenografts and murine tumors. Results In a series of in vitro studies, PEDF was shown to inhibit endothelial cell activation and to stimulate differentiation of NB cell lines. After tail vein injection of rAAV-hPEDF, stable transgene expression was generated and correlated with levels of vector administration. Human NB xenograft growth was restricted by hPEDF in a dose-dependent fashion. Intratumoral VEGF expression and microvessel density were decreased, and tumor cell apoptosis was increased in PEDF-treated mice. Conclusions Treatment with PEDF had a significant impact on NB growth in mice when delivered continuously using a gene therapy–mediated approach. The activity of PEDF appears to be mediated in part by inhibition of tumor-induced angiogenesis through down-regulation of tumor-elaborated VEGF, with subsequent intratumoral apoptosis. Furthermore, hPEDF was able to induce NB differentiation in vitro and in vivo. In addition, antitumor efficacy was seen when mouse PEDF was used to treat syngeneic murine tumors. In our murine models, gene therapy–mediated delivery of PEDF appears promising for the treatment of neuroblastoma.

Restriction of neuroblastoma angiogenesis and growth by interferon-α/β

PurposeWe tested the hypothesis that the antiangiogenic activity of the type I interferons (IFNs), could affect tumor engraftment and growth in murine xenograft models of neuroblastoma. MethodsSubcutaneous and retroperitoneal human neuroblastoma xenografts were established in SCID mice. Five days after tumor cell inoculation, daily subcutaneous injections of human IFN-α at several different doses were initiated and continued for 30 days. The effectiveness of continuous delivery of low-dose interferon was then tested using a gene therapy approach in which an adeno-associated virus vector encoding IFN-β (rAAV-IFN-β) was used to mediate expression prior to retroperitoneal tumor implantation. ResultsSubcutaneous and retroperitoneal tumors were significantly smaller in IFN-α–treated mice, as compared with control mice. Intratumoral basic fibroblast growth factor and vascular endothelial growth factor expression were also decreased, as was mean intratumoral endothelial cell density. Interestingly, the lower doses of IFN-α were more effective than the higher dose. No tumors developed in any of the mice given rAAV-IFN–β, whereas each of the mice that received control vector developed large tumors. ConclusionsTreatment with IFN had a significant impact on neuroblastoma engraftment and growth in mice, particularly when delivered continuously using a gene therapy approach. This activity appears to be mediated in part by inhibition of tumor-induced angiogenesis through the downregulation of tumor-elaborated factors, including basic fibroblast growth factor and vascular endothelial growth factor.

Radiolabeled tracers for imaging of tumor angiogenesis and evaluation of anti-angiogenic therapies.

A variety of therapeutic strategies in oncology are focused on the inhibition of tumor-induced angiogenesis. Thus, there is a keen interest in methods which allow non-invasive monitoring of molecular targets involved in angiogenesis which would support information for planning and controlling corresponding therapies. Moreover, such techniques would provide an insight into the formation of new sprouting blood vessels, the involved processes and regulatory mechanisms in patients. At the moment, development of radiotracer based techniques is mainly concentrated on three different targets which include peptidic and non-peptidic alpha v beta 3-integrin binding antagonists, matrix metalloproteinase inhibitors and single chain anti-fibronectin antibody fragments. Development of radiolabeled MMP inhibitors is based on either the decapeptide Cys-Thr-Thr-His-Trp-Gly-Phe-Thr-Leu-Cys resulting from a phage display library or small molecular weight compounds. The in vitro data for these tracers are very promising. However, more detailed in vivo data are necessary to evaluate the potency of MMP-inhibitors for in-vivo imaging. The radiolabelled anti-ED-B single chain antibody fragment scFv L-19 shows selective accumulation in the tumor vasculature in a murine tumour model. In a first patient study a selective localisation of the (123)I-labeled tracer in lesions of different tumours was found. On the basis of the lead structure cyclo(-Arg-Gly-Asp-dPhe-Val) a variety of different radiolabeled RGD-peptides has been developed for the non-invasive determination of the alpha v beta 3 expression. These developments include peptides labeled with minimum structural alteration, peptide carbohydrate conjugates, peptidomimetics based on the RGD-structure as well as heterodimeric, homodimeric and homotetrameric ligand systems. Many of the tracers show high alpha v beta 3-affinity and selectivity in vitro and receptor selective tumour accumulation with high image contrast in different murine tumour models. Further studies have to demonstrate that this approach can be translated to clinical settings allowing visualisation of alpha v beta 3-positive tumours and alpha v beta 3 expression during tumour-induced angiogenesis in patients.

Identification and Biological Characterization of Angiogenic and Tumor Growth Inhibitors derived from Sinica cetorhinus maximum Cartilage

Shark (Sinica cetorhinus maximum) cartilage was extracted in 1 mol/L Gu-HCl guanidine. Two purified active proteins with apparent molecular weights of 15.2x103 Da and 8.0×103 Da (designated as Sp15 and Sp8, respectively) were obtained through ultrafiltration and Superdex 75 chromatography. The activities of the samples were studied in terms of their potential inhibition of vascular endothelial cell growth in vitro, of angiogenesis both in rabbit cornea and chick embryo chorioallantoic membrane (CAM) assay models in vivo, and of growth of transplanted S180 sarcoma in mice in vivo. The results showed that Sp15 expressed a typical lysozymatic activity up to 223,000 U/mg and its N-terminus was highly homologous to lysozymes of various mammalian origins. Sp15 exhibited a strong anti-angiogenic activity only in vitro, whereas Sp8 shared this effect both in vitro and in vivo. Both Sp15 and Sp8 provided an effective anti-tumor activity in mice bearing transplanted S180 sarcoma. These results suggest that Sp15 is a shark cartilage-derived lysozyme that participates in the defense to bacterial invasion to the body, while Sp8 is an angiogenic inhibitor that mediates at least part of the anti-tumor activity associated with shark cartilage probably through the inhibition of tumor-induced angiogenesis.

Inhibition of Tumor-Induced Angiogenesis and Matrix-Metalloproteinase Expression in Confrontation Cultures of Embryoid Bodies and Tumor Spheroids by Plant Ingredients Used in Traditional Chinese Medicine

Tumor-induced angiogenesis is a prerequisite for excessive tumor growth. Blood vessels invade the tumor tissue after degradation of the extracellular matrix scaffold by matrix metalloproteinases (MMPs). Inhibition of MMPs has been therefore suggested to be a useful tool to abolish neoangiogenesis of solid tumors. In the present study, antioxidative plant ingredients used in traditional Chinese medicine were investigated for their capacity to down-regulate MMP expression and to inhibit angiogenesis in embryonic stem cell–derived embryoid bodies and tumor-induced angiogenesis in confrontation cultures consisting of embryoid bodies and multicellular DU-145 prostate tumor spheroids. Embryoid bodies transiently expressed MMP-1, MMP-2, and MMP-9 during the time of differentiation of capillary-like structures. In confrontation cultures, MMP expression was increased compared with control tumor spheroids and embryoid bodies cultivated separately. The increased expression of MMPs in confrontation cultures was a result of elevated levels of reactive oxygen species (ROS) upon confrontation culture and was totally abolished in the presence of the free radical scavenger vitamin E. Incubation of embryoid bodies with baicalein, epicatechin, berberine, and acteoside, which are herbal ingredients used in traditional Chinese medicine, significantly inhibited angiogenesis in embryoid bodies and decreased intracellular ROS levels. Tumor-induced angiogenesis in confrontation cultures was totally abolished in the presence of the free radical scavenger vitamin E. Because herbal ingredients down-regulated MMP expression, we conclude that ROS generated during confrontation culture induce the expression of MMPs that are necessary for endothelial cell invasion into the tumor tissue.

Inhibitory effect of BCG cell-wall skeletons (BCG-CWS) emulsified in squalane on tumor growth and metastasis in mice.

The antimetastatic effect of BCG-CWS, which was emulsified in an oil-in-water form with either Drakeol 6VR mineral oil (BCG-CWS/DK) or squalane (BCG-CWS/SQA), on lung metastasis produced by highly metastatic murine tumor cells, Colon26-M3.1 carcinoma cells and B16-BL6 melanoma cells, was investigated in syngeneic mice. An intravenous (i.v.) administration of BCG-CWS (100 mg/mouse) 1 day after tumor inoculation significantly inhibited tumor metastasis of both Colon26-M3.1 carcinoma and B16-BL6 melanoma cells in experimental lung metastasis models. No differences in the antitumor activity of the two oil-based formulations (BCG-CWS/DK and BCG-CWS/SQA) were obverved. However, BCG-CWS/SQA administered through subcutaneous (s.c.) route was shown to be effective only when it was consecutively injected (3 times) after tumor inoculation. An in vivo analysis for tumor-induced angiogenesis showed that a single i.v. administration of BCG-CWS/SQA inhibited the number of tumor-induced blood vessels and suppressed tumor growth. Furthermore, the multiple administration of BCG-CWS/SQA given at on week intervals led to a significant reduction in spontaneous lung metastasis of B16-BL6 melanoma cells in a spontaneous metastasis model. These results suggest that BCG-CWS emulsified with squalane is a potent inhibitory agent of lung metastasis, and that the antimetastatic effect of BCG-CWS is related to the suppression of tumor growth and the inhibition of tumor-induced angiogenesis.

Expression of angiostatin cDNA in a murine renal cell carcinoma suppresses tumor growth in vivo

Objectives. To investigate the effectiveness of angiostatin gene therapy for renal cancer using a mouse model. The generally poor prognosis of advanced renal cancer indicates the need for new therapeutic modalities. The dependency of solid tumor growth on angiogenesis suggests that antiangiogenic therapy would be effective against renal cell carcinoma, which is generally a hypervascular tumor. Methods. Murine renal cancer cells (Renca) transfected with murine angiostatin cDNA (AST-Renca) were subcutaneously implanted in BALB/c mice. Subsequently, the macroscopic appearance and volume of tumors were evaluated once per week. Renca cells transfected with empty plasmid DNA (mock-Renca) were used as a control. In addition, histologic sections of tumor were analyzed for neovascularization on the basis of an immunohistochemical analysis for CD31. The antitumor effect of AST-Renca on a parental Renca tumor at a distant site was also evaluated. Results. The mean volume of AST-Renca tumors was significantly less than that of the control vector-transfected tumors 3 weeks after implantation. In the cell proliferation assay, the expression of angiostatin did not inhibit the proliferation of Renca cells in vitro. Immunohistochemical analysis of neovascularization by staining with anti-CD31 antibody revealed that angiostatin suppressed tumor vessel formation. Moreover, implantation of AST-Renca inhibited the growth of parental Renca implanted simultaneously at a distant site. Conclusions. Expression of an angiostatin transgene can suppress the growth of murine renal cancer through the inhibition of tumor-induced angiogenesis. Angiostatin gene therapy may be effective against renal cancer.

Wound-induced angiogenesis and its pharmacologic inhibition in a murine model

A novel synthetic compound, SU5416, inhibits subcutaneous tumor growth of cells. Because angiogenesis in tumor growth and wound healing involves similar mechanisms, we examined whether SU5416 inhibits wound-induced angiogenesis. Sixteen female BALB/c mice were randomized to receive either SU5416 (n = 8) or vehicle alone (n = 8) on day -2. On day 0, transparent window chambers were implanted into the dorsal skin flap. Treatment was stopped on day 7. On days 1, 7, and 14, micrographs of the windows were taken and microvessel density was estimated. On day 1, no statistically significant difference was noted between the microvessel density in controls and treatments. After the mice underwent treatment from day -2 to day 7 and microvessel densities were analyzed on day 7, angiogenesis was significantly inhibited in the SU5416 group (P <.001). Seven days after cessation of treatment, however, the SU5416 group showed complete recovery in angiogenesis. The increase in microvessel density in the SU5416 group on day 14 from day 7 was not significantly different from that of the control group (P >.05). We observed that SU5416, a known inhibitor of tumor-induced angiogenesis, also inhibited wound-induced angiogenesis in our murine wound model. This inhibitory effect is significant while the mice are undergoing treatment.