Mechanisms and future directions for angiogenesis-based cancer therapies

1,3,5-Tricaffeoylquinic Acid from Ipomoea batatas Vines Induced Ovarian Cancer Cell Apoptosis and Inhibited Endothelial Tube Formation

Ovarian cancer usually metastasizes from the ovary to adjacent organs through direct invasion with blood vessels formed by endothelial cells. Targeting apoptosis of ovarian cancer and angiogenesis is promising for anticancer therapy. Leaves of Ipomoea sp. have reportedly shown promise in treating ovarian cancer. Here, we investigated the apoptosis-inducing and anti-angiogenic effects of compounds isolated from Ipomoea batatas vines (IBV). Phytochemical examination of IBV led to the isolation and verification of eight compounds (1-8): chlorogenic acid (1), 3,4-dicaffeoylquinic acid (2), 3,5-dicaffeoylquinic acid (3), 4,5-dicaffeoylquinic acid (4), 1,3,5-tricaffeoylquinic acid (5), N-trans-feruloyltyramine (6), scopoletin (7), and esculetin (8). Of these, 1,3,5-tricaffeoylquinic acid (5) showed the highest cytotoxicity in A2780 human ovarian cancer cells, inducing apoptotic death in more than 37% cells and decreasing viability to less than 25% at 100 μM. Compound 5 increased the levels of cleaved caspase-8, Bax, cleaved PARP, and caspase-3/9, and decreased the levels of cleaved Bcl-2. Further, 5 inhibited tubule formation in HUVECs. VEGFR2, ERK, PI3K, Akt, and mTOR protein expression was also suppressed by 5. Then, a simple, rapid, and reliable LC-MS/ MS method was developed to determine the contents of the isolated compounds from IBV. Overall, 5 has potential for treating ovarian cancer as it induces apoptosis in ovarian cancer cells and inhibits tube formation.

Toxic metals in the regulation of epithelial-mesenchymal plasticity: demons or angels?

Epithelial cells can trans-differentiate into motile mesenchymal cells through a dynamic process known as epithelial-mesenchymal transition (EMT). EMT is crucial in embryonic development and wound healing but also contributes to human diseases such as organ fibrosis and cancer progression. Heavy metals are environmental pollutants that can affect human health in various ways, including causing cancers. The cytotoxicity and carcinogenicity of heavy metals are complex, and studies have demonstrated that some of these metals can affect the progress of EMT. Here, we focus on reviewing the roles of six environmentally common toxic metals concerning EMT: arsenic (AS), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni), and copper (Cu). Noteworthily, the effects of these elements on EMT may vary according to the form, dose, and exposure time; the dual role of heavy metals (e.g., AS, Cd, and Cu) on EMT is also observed, in which, sometimes they can promote while sometimes inhibit the EMT process. Given the vast number of toxicologically relevant metals that exist in nature, we believe a comprehensive understanding of their effects on EMT is required to dictate in what circumstances these metals act more likely as demons or angels.

Hypoxia and the Tumor Microenvironment

Hypoxia is an important feature of the tumor microenvironment, and is closely associated with cell proliferation, angiogenesis, metabolism and the tumor immune response. All these factors can further promote tumor progression, increase tumor aggressiveness, enhance tumor metastatic potential and lead to poor prognosis. In this review, these effects of hypoxia on tumor biology will be discussed, along with their significance for tumor detection and treatment.

Intersecting Mechanisms of Hypoxia and Prostaglandin E2-Mediated Inflammation in the Comparative Biology of Oral Squamous Cell Carcinoma

The importance of inflammation in the pathogenesis of cancer was first proposed by Rudolph Virchow over 150 years ago, and our understanding of its significance has grown over decades of biomedical research. The arachidonic acid pathway of inflammation, including cyclooxygenase (COX) enzymes, PGE2 synthase enzymes, prostaglandin E2 (PGE2) and PGE2 receptors has been extensively studied and has been associated with different diseases and different types of cancers, including oral squamous cell carcinoma (OSCC). In addition to inflammation in the tumour microenvironment, low oxygen levels (hypoxia) within tumours have also been shown to contribute to tumour progression. Understandably, most of our OSCC knowledge comes from study of this aggressive cancer in human patients and in experimental rodent models. However, domestic animals develop OSCC spontaneously and this is an important, and difficult to treat, form of cancer in veterinary medicine. The primary goal of this review article is to explore the available evidence regarding interaction between hypoxia and the arachidonic acid pathway of inflammation during malignant behaviour of OSCC. Overlapping mechanisms in hypoxia and inflammation can contribute to tumour growth, angiogenesis, and, importantly, resistance to therapy. The benefits and controversies of anti-inflammatory and anti-angiogenic therapies for human and animal OSCC patients will be discussed, including conventional pharmaceutical agents as well as natural products.

Sustained oxidative stress instigates differentiation of cancer stem cells into tumor endothelial cells: Pentose phosphate pathway, reactive oxygen species and autophagy crosstalk

Tumor angiogenesis plays a vital role in tumor growth and metastasis. It is proven that in tumor vasculature, endothelial cells (ECs) originate from a small population of cancer cells introduced as cancer stem cells (CSCs). Autophagy has a vital role in ECs differentiation from CSCs and tumor angiogenesis. High levels of reactive oxygen species (ROS) increased autophagy by inhibition of glucose-6-phosphate dehydrogenase (G6PD) and inactivation of the pentose phosphate pathway (PPP). Previously, we suggested that cancer cells initially increase the glycolysis rate when encountering ROS, then the metabolic balance is changed from glycolysis to PPP, following the continuation of oxidative stress. In this study, we investigate the possible role of persistent oxidative stress in the differentiation of CSCs into tumor ECs by relying on the relationship between the ROS, PPP and autophagy. Because tumor angiogenesis plays an important role in the growth and development of cancer, understanding the mechanisms involved in differentiating ECs from CSCs can help find promising treatments for cancer.

Correlation of gene polymorphisms of vascular endothelial growth factor with grade and prognosis of lung cancer

Background

Vascular endothelial growth factor (VEGF) gene is highly polymorphic, and single nucleotide polymorphisms (SNP) of VEGF gene are associate with cancer prognosis. This study aimed to analyze the correlation of VEGF gene polymorphisms with grade and prognosis of lung cancer.

Methods

A total of 458 Chinese patients with primary lung cancer were enrolled from September 2008 to October 2013. The genotypes of −2578C > A, −1154G > A, − 460 T > C, and + 405G > C were analyzed in white blood cells from patients using polymerase chain reaction based restriction fragment length polymorphism.

Results

Our data showed that –1154G > A polymorphism was significantly associated with tumor stages, but all four tested VEGF gene polymorphisms had no significant effect on survival.

Conclusions

VEGF polymorphisms may relate to stage of lung cancer in Chinese population.

Inhibition of constructed SEC3-ES lentiviral vector to proliferation, migration of Hela cells

AIM

To construct a lentiviral vector with endostatin (ES) and staphylococcal enterotoxin C₃(SEC3) gene, and investigate its capacities of inhibition on proliferation and migration of Hela cells.

METHODS

By inserting ES and SEC3 gene into the plasmid and then transfect 293 T cell, the co-expressed (SEC3-ES) vector were constructed. A series of experiments in vitro were carried out to detect its anti-tumor capacity.

RESULTS

SEC3 expression of the vector is about 3 times of GV365-SEC3 vector, and ES expression is over 22.5-fold compared with GV365-ES vector. Moreover, OD490 value of CO group (1.212 ± 0.003) was notably lower than NC (negative control) group (1.124 ± 0.01) (P < 0.05) in MTT assay. Cell cycle analysis showed it could block Hela cells in S phase. Meanwhile, in wound healing assay, cells of CO group migrated at a slower rate (0.59 ± 0.02) compared with NC group (0.65 ± 0.02)(P < 0.01).

CONCLUSION

The successful construction of co-expressed vector lays the foundation for further studies in vivo. These promising results suggest a new strategy to treating cervical cancer.

Reversal of Resistance in Targeted Therapy of Metastatic Melanoma: Lessons Learned from Vemurafenib (BRAFV600E-Specific Inhibitor)

Malignant melanoma is the most aggressive form of skin cancer and has a very low survival rate. Over 50% of melanomas harbor various BRAF mutations with the most common being the V600E. BRAF^V600E mutation that causes constitutive activation of the MAPK pathway leading to drug-, immune-resistance, apoptosis evasion, proliferation, survival, and metastasis of melanomas. The ATP competitive BRAF^V600E selective inhibitor, vemurafenib, has shown dramatic success in clinical trials; promoting tumor regression and an increase in overall survival of patients with metastatic melanoma. Regrettably, vemurafenib-resistance develops over an average of six months, which renders melanomas resistant to other therapeutic strategies. Elucidation of the underlying mechanism(s) of acquisition of vemurafenib-resistance and design of novel approaches to override resistance is the subject of intense clinical and basic research. In this review, we summarize recent developments in therapeutic approaches and clinical investigations on melanomas with BRAF^V600E mutation to establish a new platform for the treatment of melanoma.

Teucrium polium Extract Enhances the Anti-Angiogenesis Effect of Tranilast on Human Umbilical Vein Endothelial Cells

Purpose: Angiogenesis plays an important role in numerous pathophysiological events like cancer. As a result of this, tranilast as an anti-fibrotic drug induces the promising antitumor activities through the inhibition of angiogenesis. Further, Teucrium polium (TP) is a herbal medicine (family Lamaceae) with antitumor properties. This study was conducted to investigate the combination effects of tranilast and T. polium on human umbilical vein endothelial cells (HUVECs) viability and apoptotic genes expression. Methods: The HUVECs line was treated using different doses of tranilast and T. polium alone or their combination. The cell cytotoxicity was evaluated using MTT and LDH assays; apoptosis was examined using acridine orange/ethidium bromide staining, nitric oxide (NO) production was evaluated using Griess reaction and the expression of BAX and BCL-2 genes were detected using real-time RT-PCR. One-way analysis of variance (ANOVA) test was used to compare the data in different groups. Results: The survival rate of HUVECs was significantly reduced (p<0.05) in a dose dependent manner by tranilast and T. polium. However, T. polium and tranilast combination significantly (p<0.001) reduced cell viability and increased apoptotic cells as compared to each drug alone. Also, HUVECs treated with Tranilast / T. polium combination showed a reduced level of NO as regards to cells exposed only to Tranilast or T. polium (p<0.05). Furthermore, a significant increase in BAX and a decrease in BCL-2 mRNA expression were observed in combination group (p<0.001). Conclusion: T. polium synergistically increased the antiangiogenic effect of tranilast on in vitro angiogenic model of HUVECs.

Platelet function is disturbed by the angiogenesis inhibitors sunitinib and sorafenib, but unaffected by bevacizumab

INTRODUCTION

At the clinical introduction of antiangiogenic agents as anticancer agents, no major toxicities were expected as merely just endothelial cells (ECs) in tumors would be affected. However, several (serious) toxicities became apparent, of which underlying mechanisms are largely unknown. We investigated to what extent sunitinib (multitargeted antiangiogenic tyrosine kinase inhibitor (TKI)), sorafenib (TKI) and bevacizumab [specific antibody against vascular endothelial growth factor (VEGF)] may impair platelet function, which might explain treatment-related bleedings.

MATERIALS AND METHODS

In vitro, the influence of sunitinib, sorafenib, and bevacizumab on platelet aggregation, P-selectin expression and fibrinogen binding, platelet-EC interaction, and tyrosine phosphorylation of c-Src was studied by optical aggregation, flow cytometry, real-time perfusion, and western blotting. Ex vivo, platelet aggregation was analyzed in 25 patients upon sunitinib or bevacizumab treatment. Concentrations of sunitinib, VEGF, and platelet and EC activation markers were measured by LC-MS/MS and ELISA.

RESULTS

In vitro, sunitinib and sorafenib significantly inhibited platelet aggregation (20 μM sunitinib: 71.3%, p < 0.001; 25 μM sorafenib: 55.8%, p = 0.042). Sorafenib and sunitinib significantly inhibited P-selectin expression on platelets. Exposure to both TKIs resulted in a reduced tyrosine phosphorylation of c-Src. Ex vivo, within 24 h sunitinib impaired platelet aggregation (83.0%, p = 0.001, N = 8). Plasma concentrations of sunitinib, VEGF, and platelet/EC activation markers were not correlated with disturbed aggregation. In contrast, bevacizumab only significantly impaired platelet aggregation in vitro at high concentrations, but not ex vivo.

CONCLUSION

Sunitinib significantly inhibits platelet aggregation in patients already after 24 h of first administration, whereas bevacizumab had no effect on aggregation. These findings may explain the clinically observed bleedings during treatment with antiangiogenic TKIs.

Interleukin-8 in cancer pathogenesis, treatment and follow-up

Interleukin-8 (CXCL8) was originally described asa chemokine whose main function is the attraction of a polymorphonuclear inflammatory leukocyte infiltrate acting on CXCR1/2. Recently, it has been found that tumors very frequently coopt the production of this chemokine, which in this malignant context exerts different pro-tumoral functions. Reportedly, these include angiogenesis, survival signaling for cancer stem cells and attraction of myeloid cells endowed with the ability to immunosuppress and locally provide growth factors. Given the fact that in cancer patients IL-8 is mainly produced by tumor cells themselves, its serum concentration has been shown to correlate with tumor burden. Thus, IL-8 serum concentrations have been shown to be useful asa pharmacodynamic biomarker to early detect response to immunotherapy. Finally, because of the roles that IL-8 plays in favoring tumor progression, several therapeutic strategies are being developed to interfere with its functions. Such interventions hold promise, especially for therapeutic combinations in the field of cancer immunotherapy.

Roles of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) Oxidase in Angiogenesis: Isoform-Specific Effects

Angiogenesis is the formation of new blood vessels from preexisting ones and is implicated in physiologic vascular development, pathologic blood vessel growth, and vascular restoration. This is in contrast to vasculogenesis, which is de novo growth of vessels from vascular precursors, or from vascular repair that occurs when circulating endothelial progenitor cells home into an area and develop into blood vessels. The objective of this review is to discuss the isoform-specific role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) in physiologic and pathologic angiogenesis and vascular repair, but will not specifically address vasculogenesis. As the major source of reactive oxygen species (ROS) in vascular endothelial cells (ECs), NOX has gained increasing attention in angiogenesis. Activation of NOX leads to events necessary for physiologic and pathologic angiogenesis, including EC migration, proliferation and tube formation. However, activation of different NOX isoforms has different effects in angiogenesis. Activation of NOX2 promotes pathologic angiogenesis and vascular inflammation, but may be beneficial in revascularization in the hindlimb ischemic model. In contrast, activation of NOX4 appears to promote physiologic angiogenesis mainly by protecting the vasculature during ischemia, hypoxia and inflammation and by restoring vascularization, except in models of oxygen-induced retinopathy and diabetes where NOX4 activation leads to pathologic angiogenesis.

Kallistatin Suppresses Cell Proliferation and Invasion and Promotes Apoptosis in Cervical Cancer Through Blocking NF-κB Signaling

Kallistatin has been recognized as an endogenous angiogenesis inhibitor and exerts pleiotropic effects in inhibiting tumor growth, migration, apoptosis, and inflammation. The purpose of the present study was to investigate the potential role and mechanisms of kallistatin in cervical cancer. We demonstrated that kallistatin effectively inhibited cell proliferation and enhanced apoptosis in a dose-dependent manner. Additionally, kallistatin suppressed migration and invasion activities and markedly reduced the expression of matrix-degrading metalloproteinases, progelatinase (MMP-2), MMP-9, and urokinase-type PA (uPA). Kallistatin reversed the epithelial-mesenchymal transition (EMT) and caused the upregulation of epithelial markers such as E-cadherin and inhibited mesenchymal markers such as N-cadherin and vimentin. Moreover, kallistatin led to a marked decrease in the expression of vascular endothelial growth factor (VEGF) and HIF-1α. In a xenograft mouse model, kallistatin treatment reduced tumor growth. Importantly, kallistatin strikingly impeded NF-κB activation by suppressing IκBα degradation and the level of phosphorylation of p65. Interestingly, similar to kallistatin, treatment with PDTC (an inhibitor of NF-κB) also attenuated cell invasion and migration. Taken together, these findings suggest that kallistatin suppresses cervical cancer cell proliferation, migration, and EMT and promotes cell apoptosis by blocking the NF-κB signaling pathway, suggesting that kallistatin may be a novel therapeutic target for cervical cancer treatment.

Angiogenesis: Basic Mechanisms and Clinical Applications

The development and maintenance of an adequate vascular supply is critical for the viability of normal and neoplastic tissues. Angiogenesis, the development of new blood vessels from preexisting capillary networks, plays an important role in a number of physiologic and pathologic processes, including reproduction, wound repair, inflammatory diseases, and tumor growth. Angiogenesis involves sequential steps that are triggered in response to angiogenic growth factors released by inflammatory, mesenchymal, or tumor cells that act as ligands for endothelial cell receptor tyrosine kinases. Stimulated endothelial cells detach from neighboring cells and migrate, proliferate, and form tubes. The immature tubes are subsequently invested and stabilized by pericytes or smooth muscle cells. Angiogenesis depends upon complex interactions among various classes of molecules, including adhesion molecules, proteases, structural proteins, cell surface receptors, and growth factors. The therapeutic manipulation of angiogenesis targeted against ischemic and neoplastic diseases has been investigated in preclinical animal models and in clinical trials. Proangiogenic trials that have stimulated vessel growth in ischemic coronary or peripheral tissues through expression, delivery, or stimulated release of growth factors have shown efficacy in animal models and mixed results in human clinical trials. Antiangiogenic trials have used strategies to block the function of molecules critical for new vessel growth or maturation in the treatment of a variety of malignancies, mostly with results less encouraging than those seen in preclinical models. Pro-and antiangiogenic clinical trials demonstrate that strategies for optimal drug delivery, dosing schedules, patient selection, and endpoint measurements need further investigation and refinement before the therapeutic manipulation of angiogenesis will realize its full clinical potential.

A Widely Applicable, High-Throughput TR-FRET Assay for the Measurement of Kinase Autophosphorylation: VEGFR-2 as a Prototype

Homogeneous time-resolved fluorescence resonance energy transfer (TR-FRET) assays represent a highly sensitive and robust high-throughput screening (HTS) method for the quantification of kinase activity. Traditional TR-FRET kinase assays detect the phosphorylation of an exogenous substrate. The authors describe the development and optimization of a TR-FRET technique that measures the autophosphorylation of vascular endothelial growth factor receptor 2 (VEGFR-2) kinase and extend its applicability to a variety of other kinases. The VEGFR-2 assay demonstrated dose-dependent inhibition by compounds known to modulate the catalytic activity of this receptor. In addition, kinetic analysis of a previously characterized VEGFR-2 inhibitor was performed using the method, and results were consistent with those obtained using a different assay format. Because of the known involvement of VEGFR-2 in angiogenesis, this assay should facilitate HTS for antiangiogenic agents. In addition, this general technique should have utility for the screening for inhibitors of kinases as potential therapeutic agents for many other disease indications.

Emerging antibody-based therapeutic strategies for bladder cancer: A systematic review

Bladder cancer is the most common malignancy of the urinary tract, presents the highest recurrence rate among solid tumors and is the second leading cause of death in genitourinary cancers. Despite recent advances in understanding of pathophysiology of the disease, the management of bladder cancer patients remains a clinically challenging problem. Particularly, bladder tumors invading the muscularis propria and disseminated disease are often not responsive to currently available therapeutic approaches, which include surgery and conventional chemotherapy. Antibody-based therapeutic strategies have become an established treatment option for over a decade in several types of cancer. However, bladder cancer has remained mostly an "orphan disease" regarding the introduction of these novel therapeutics, which has been translated in few improvements in patients overall survival. In order to shift this paradigm, several clinical studies involving antibody-based therapeutic strategies targeting the most prominent bladder cancer-related biomolecular pathways and immunological mediators are ongoing. This systematic review explores antibody-based therapeutics for bladder cancer undergoing clinical trial and discusses the future perspectives in this field, envisaging the development of more effective guided therapeutics.

Copper depletion inhibits CoCl2-induced aggressive phenotype of MCF-7 cells via downregulation of HIF-1 and inhibition of Snail/Twist-mediated epithelial-mesenchymal transition

Copper, a strictly regulated trace element, is essential for many physiological processes including angiogenesis. Dysregulated angiogenesis has been associated with increased copper in tumors, and thus copper chelators have been used to inhibit tumor angiogenesis. However, it remains unclear whether copper has any effect on epithelial-mesenchymal transition (EMT). Using CoCl2-induced EMT of human breast carcinoma MCF-7 cells, we found that TEPA, a copper chelator, inhibited EMT-like cell morphology and cytoskeleton arrangement triggered by CoCl2; decreased the expression of vimentin and fibronectin, markers typical of EMT; inhibited HIF-1 activation and HIF1-α accumulation in nuclear; and down-regulated the expression of hypoxia-associated transcription factors, Snail and Twist1. Moreover, knockdown copper transport protein, Ctr1, also inhibited CoCl2-induced EMT and reversed the mesenchymal phenotype. In EMT6 xenograft mouse models, TEPA administration inhibited the tumor growth and increased mice survival. Immunohistochemical analysis of the xenograft further demonstrated that TEPA administration significantly inhibited tumor angiogenesis, down-regulated hypoxia-induced transcription factors, Snail and Twist1, leading to decreased transactivation of EMT-associated marker genes, vimentin and fibronectin. These results indicate that TEPA inhibits CoCl2-induced EMT most likely via HIF1-α-Snail/Twist signaling pathway, and copper depletion may be exploited as a therapeutic for breast cancer.

Treatment of Hepatic Epithelioid Hemangioendothelioma: Finding Uses for Thalidomide in a New Era of Medicine

Hepatic epithelioid hemangioendothelioma (HEH) is extremely rare, occurring in 1 to 2 per 100,000, with chemotherapy options not well defined. Our case involved a 49-year-old female who had hepatic masses and metastasis to the lungs with a liver biopsy revealing HEH. After developing a rash from sorafenib, thalidomide was started with the progression of disease stabilized. Resection is only an option in 10% of the cases; therefore, chemotherapy is the only line of treatment. Newer chemotherapy alternatives are targeting angiogenesis via the vascular endothelial growth factor. Thalidomide was first used as an antiemetic, but, sadly, soon linked to phocomelia birth defects. Given the mechanism of action against angiogenesis, thalidomide has a valid role in vascular tumors. In conclusion, the use of thalidomide as chemotherapy is novel and promising, especially in the setting of a rare vascular liver tumor such as HEH.

Novel angiogenesis inhibitors in nonsmall cell lung cancer

PURPOSE OF REVIEW

The fact that growth and spread of tumours are dependent on angiogenesis has led to the investigation of the role of antiangiogenic agents in the therapeutic strategies for thoracic tumours such as nonsmall cell lung cancer (NSCLC). This review summarizes and evaluates the recent developments in this field.

RECENT FINDINGS

Bevacizumab, an antivascular endothelial growth factor antibody, has been approved for the treatment of patients with advanced NSCLC of nonsquamous histology in combination with a platinum-containing chemotherapy. Like in other cancer entities, the antiangiogenic concept in NSCLC comprises maintenance therapy with the antiangiogenic compound until disease progression. Moreover, over the last years, new antiangiogenic agents have been tested in clinical trials in NSCLC patients. Recent trials have demonstrated the efficacy of antiangiogenic agents in combination with docetaxel in the second-line setting.

SUMMARY

These studies - together with experiences from other cancer entities - have revived the field of antiangiogenic treatment in lung cancer.

Natural phenolic metabolites with anti-angiogenic properties - a review from the chemical point of view

Considering the many secondary natural metabolites available from plants, phenolic compounds play a particularly important role in human health as they occur in significant amounts in many fruits, vegetables and medicinal plants. In this review natural phenolic compounds of plant origin with significant anti-angiogenic properties are discussed. Thirteen representatives from eight different natural or natural-like phenolic subclasses are presented with an emphasis on their synthesis and methods to modify the parent compounds. When available, the consequence of structural variation on the pharmacological activity of the molecules is described.

Antioxidant and antiangiogenic properties of phenolic extract from Pleurotus tuber-regium

Pleurotus tuber-regium (Fries) Singer (PTR), both an edible and a medicinal mushroom also known as tiger milk mushroom, has experienced growing popularity and economic importance due to its flavor, nutritive value, and medicinal effects. In this study, the antioxidant and antiangiogenic activities of a 60% ethanol extract (EE) obtained from the sclerotium of PTR were investigated. Typical phenolic compounds including protocatechuic, chlorogenic, syringic, ferulic, and folic acid were identified and quantified in EE by the HPLC-UV-ESI/MS analyses. EE possessed strong antioxidant activity and could dose-dependently inhibit vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cells (HUVEC) migration and tube formation. qPCR results showed that VEGF-induced FGF, ANG-Tie, and MMP gene expression as well as VEGFR were down-regulated at the mRNA level after treated with EE, suggesting that multiple molecular targets related to angiogenesis was involved. Furthermore, EE also inhibited the formation of subintestinal vessel plexus (SIVs) in zebrafish embryos in vivo. All of these suggested that EE of PTR could be the source of potential inhibitors to target angiogenesis.

Bacterial surface display of endoglin by antigen 43 induces antitumor effectiveness via bypassing immunotolerance and inhibition of angiogenesis

Various angiogenesis-related self-molecules have been considered to be therapeutic targets. However, the direct use of self-molecules as vaccines is not recommended because of the inherent ability of the host to develop immune tolerance. Antigen 43 (Ag43) is a surface protein found in E. coli and contains an α and a β subunits, which contains multiple T epitopes in α subunit. Here we construct a novel Ag43 surface display system (Ag43 system) to express Ag43 chimeric proteins to disrupt immune tolerance against self-molecules. The Ag43 system was constructed from an Escherichia coli strain Tan109, derived from JM109, in which the Ag43 gene was deleted and a recombinant plasmid (pETAg43') expressing a partial Ag43 gene was introduced. The extracellular domain of angiogenesis-related endoglin gene was then subcloned into plasmid pETAg43', resulting in a recombinant plasmid pETAg43'/END(e) which was then used to transform Tan109 for protein expression. We found that Ag43 and endoglin chimeric protein (Ag43'/END(e) ) was expressed on the bacterial surface. The chimeric protein could be separated from the bacterial surface by heating to 60°C and yet retain activity. We used Ag43'/END(e) as a protein vaccine and found that it could disrupt immune tolerance against endoglin by inducing significant antitumor activities and inhibit angiogenesis in several tumor models without significant side effects. These data suggest that Ag43'/END(e) chimeric protein is a potential model vaccine for active tumor immunotherapy, and that Ag43 system could be an effective tool for novel vaccine preparation to break immune tolerance to other angiogenesis-related self-molecules for cancer therapy.

Clinical trials of antiangiogenic therapy in non-small cell lung cancer: focus on bevacizumab and ZD6474

Lung cancer is the leading cause of cancer deaths in the USA. Despite the development of new chemotherapy regimens, the prognosis remains poor. Several studies comparing various platinum-based regimens failed to produce a significant impact in the outcomes for patients with non-small cell lung cancer and this therapeutic modality appears to be reaching a plateau. It has become clear that further advances will require the addition of agents with a different mechanism of action. Bevacizumab is the antiangiogenic agent at the most advanced stage of development in the treatment of cancer. Bevacizumab is synergistic with chemotherapy and usually well tolerated. The addition of bevacizumab to chemotherapy improved survival in patients with metastatic non-small cell lung cancer in a randomized clinical trial. Several small molecule antiangiogenic agents are in development. In this article, currently available data from clinical trials of antiangiogenic compounds in advanced non-small cell lung cancer are reviewed.

Molecular neuro-oncology and development of targeted therapeutic strategies for brain tumors. Part 2: PI3K/Akt/PTEN, mTOR, SHH/PTCH and angiogenesis

Brain tumors are a diverse group of malignancies that remain refractory to conventional treatment approaches. Molecular neuro-oncology has now begun to clarify the transformed phenotype of brain tumors and identify oncogenic pathways that might be amenable to targeted therapy. Activity of the phosphoinositide 3; kinase (PI3K)/Akt pathway is often upregulated in brain tumors due to excessive stimulation by growth factor receptors and Ras. Loss of function of the tumor suppressor gene PTEN also frequently contributes to upregulation of PI3K/Akt. Several compounds, such as wortmannin and LY-294002, can target PI3K and inhibit activity of this pathway. The mammalian target of rapamycin (mTOR) is an important regulator of cell growth and metabolism and is often upregulated by Akt. Clinical trials of CCI-779, an inhibitor of mTOR, are ongoing in recurrent malignant glioma patients. The sonic hedgehog/PTCH pathway is involved in the tumorigenesis of some familial and sporadic medulloblastomas. This pathway can be targeted by cyclopamine, which is under evaluation in preclinical studies. Angiogenesis is a critical process for development and progression of brain tumors. Targeted approaches to inhibit angiogenesis include monoclonal antibodies, receptor tyrosine kinase inhibitors, antisense oligonucleotides and gene therapy. Clinical trials are ongoing for numerous angiogenesis inhibitors, including thalidomide, CC-5103 and PTK 787/ZK 222584. Further development of targeted therapies and evaluation of these new agents in clinical trials will be needed to improve survival and quality of life of patients with brain tumors.

The role of vascular epithelial growth factor receptor-tyrosine kinase inhibitors in the treatment of advanced breast cancer: a meta-analysis of 12 randomized controlled trials

AIM

To perform a systematic review and meta-analysis of randomized controlled trials to determine the efficacy and toxicity of approved vascular epithelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) in advanced breast cancer.

METHODS

A comprehensive literature search for studies published up to August 2013 was performed. The endpoints were overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and grade 3 or 4 adverse event (AEs). The pooled hazard ratio (HR) or relative risk (RR), and 95% confidence intervals (CI) were calculated employing fixed- or random-effects models depending on the heterogeneity of the included trials.

RESULTS

Twelve randomized controlled trials involved 3256 patients were ultimately identified. The intention to treatment (ITT) analysis demonstrated that VEGFR-TKI therapy significantly improved ORR (RR 1.14, 95% CI: 1.03-1.28, p = 0.016), but it did not translate into benefits in PFS (HR 0.99, 95% CI: 0.81-1.22, p = 0.93) and OS (HR 1.11, 95% CI 0.99-1.24, p = 0.084) when compared to non-VEGFR-TKI therapy. Additionally, a higher incidence of grade 3 or 4 anemia, neutropenia, thrombocytopenia, diarrhea, hand-foot syndrome and fatigue was observed in VEGFR-TKI-based therapy.

CONCLUSIONS

The VEGFR-TKI-based therapy offered a significant improvement in ORR in patients with advanced breast cancer but did not benefit PFS and OS. With present available data from randomized clinical trials, we were still unable to clearly set the role of VEGFR-TKIs in the treatment of metastatic breast cancer (MBC).

Combination antiangiogenic therapy and radiation in head and neck cancers

Tumor angiogenesis is a hallmark of advanced cancers and promotes invasion and metastasis. Over 90% of head and neck squamous cell carcinomas (HNSCC) express angiogenic factors such as vascular endothelial growth factor (VEGF). Several preclinical studies support the prognostic implications of angiogenic markers for HNSCC and currently this is an attractive treatment target in solid tumors. Since radiotherapy is one of the most commonly used treatments for HNSCC, it is imperative to identify the interactions between antiangiogenic therapy and radiotherapy, and to develop combination therapy to improve clinical outcome. The mechanisms between antiangiogenic agents and ionizing radiation are complicated and involve many interactions between the vasculature, tumor stroma and tumor cells. The proliferation and metastasis of tumor cells rely on angiogenesis/blood vessel formation. Rapid growing tumors will cause hypoxia, which up-regulates tumor cell survival factors, such as hypoxia-inducing factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF), giving rise to more tumor proliferation, angiogenesis and increased radioresistance. Thus, agents that target tumor vasculature and new tumor vessel formation can modulate the tumor microenvironment to improve tumor blood flow and oxygenation, leading to enhanced radiosensitivity. In this review, we discuss the mechanisms of how antiangiogenic therapies improve tumor response to radiation and data that support this combination strategy as a promising method for the treatment of HNSCC in the future.

Targeted therapy against EGFR and VEGFR using ZD6474 enhances the therapeutic potential of UV-B phototherapy in breast cancer cells

Background

The hypoxic environment of tumor region stimulated the up regulation of growth factors responsible for angiogenesis and tumor proliferation. Thus, targeting the tumor vasculature along with the proliferation by dual tyrosine kinase inhibitor may be the efficient way of treating advanced breast cancers, which can be further enhanced by combining with radiotherapy. However, the effectiveness of radiotherapy may be severely compromised by toxicities and tumor resistance due to radiation-induced adaptive response contributing to recurrence and metastases of breast cancer. The rational of using ZD6474 is to evaluate the feasibility and efficacy of combined VEGFR2 and EGFR targeting with concurrent targeted and localized UV-B phototherapy in vitro breast cancer cells with the anticipation to cure skin lesions infiltrated with breast cancer cells.

Materials and methods

Breast cancer cells were exposed to UV-B and ZD6474 and the cell viability, apoptosis, invasion and motility studies were conducted for the combinatorial effect. Graphs and statistical analyses were performed using Graph Pad Prism 5.0.

Results

ZD6474 and UV-B decreased cell viability in breast cancers in combinatorial manner without affecting the normal human mammary epithelial cells. ZD6474 inhibited cyclin E expression and induced p53 expression when combined with UV-B. It activated stress induced mitochondrial pathway by inducing translocation of bax and cytochrome-c. The combination of ZD6474 with UV-B vs. either agent alone also more potently down-regulated the anti-apoptotic bcl-2 protein, up-regulated pro-apoptotic signaling events involving expression of bax, activation of caspase-3 and caspase-7 proteins, and induced poly (ADP-ribose) polymerase resulting in apoptosis. ZD6474 combined with UV-B inhibited invasion of breast cancer cells in vitro as compared to either single agent, indicating a potential involvement of pro-angiogenic growth factors in regulating the altered expression and reorganization of cytoskeletal proteins in combinatorial treated breast cancer cells. Involvement of combination therapy in reducing the expression of matrix metalloprotease was also observed.

Conclusions

Collectively, our studies indicate that incorporating an anti-EGFR plus VEGFR strategy (ZD6474) with phototherapy (UV-B), an alternative approach to the ongoing conventional radiotherapy for the treatment of infiltrating metastatic breast cancer cells in the skin and for locally recurrence breast cancer than either approach alone.

Development of a multiplex sandwich aptamer microarray for the detection of VEGF165 and thrombin

In this work we have developed a multiplex microarray system capable of detecting VEGF₁₆₅ and thrombin. We recently described a Sandwich Aptamer Microarray (SAM) for thrombin detection feasible for use in multiplex microarrays; here we describe a new aptasensor for VEGF₁₆₅ detection employing Vap7 and VEa5, two DNA aptamers recognizing different sites of the protein. The aptamers were modified to be adapted to the solid phase platform of SAM and their capability to simultaneously recognize VEGF₁₆₅ by forming a ternary complex was analyzed in solution. Having so defined the best tandem arrangement of modified aptamers, we set up the aptasensor for VEGF₁₆₅, and finally analyzed the multiplex system with the two aptasensors for the simultaneous detection of VEGF₁₆₅ and thrombin. The results indicate that each sandwich is specific, even when the two proteins are mixed. The system performance is consistent with the behavior evidenced by the biochemical analysis, which proves to be valuable to drive the evaluation and refinement of aptamers prior to or along the development of a detection platform. Since thrombin upregulates VEGF expression, the simultaneous recognition of these two proteins could be useful in the analysis of biomarkers in pathologies characterized by neo-angiogenesis.

Development of a biosensor-based immunogenicity assay capable of blocking soluble drug target interference

As with other protein therapeutics, trebananib (AMG 386), an investigational peptide Fc-fusion protein ("peptibody") that inhibits angiogenesis by neutralizing the interaction of angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) with the Tie2 receptor, has the potential to trigger an immune response in cancer patients treated with the therapeutic. An electrochemiluminescence bridging anti-drug antibody (ADA) assay that was utilized to support early-phase clinical trials in the development of trebananib was found to lack adequate sensitivity and drug tolerance in later-phase clinical studies when higher doses of trebananib were administered. Therefore, we developed a surface plasmon resonance (SPR) immunoassay method utilizing a secondary confirmatory detector antibody (goat anti-human IgG F[ab']2) known to cross-react with human IgG and IgM to better assess the potential impact of immunogenicity on the pharmacokinetics, pharmacodynamics, and toxicity of trebananib. The SPR method was more sensitive than the electrochemiluminescence bridging assay because of signal amplification from the confirmatory binding of the detector antibody; drug tolerance was improved since antibody binding avidity does not affect detection on this platform. Despite the inability of the confirmatory detector antibody to bind angiopoietins in protein-free buffer, false-positive ADA results were generated from patient serum samples containing Ang1 and Ang2 through an apparently specific binding between the angiopoietins and the confirmatory detector antibody, likely mediated by the interaction of the angiopoietins with serum immunoglobulins. Addition to the sample diluent of a human antibody that specifically binds to Ang1 and Ang2 with high affinity resulted in a complete block of angiopoietin interference without affecting ADA detection. This biosensor-based assay provides a reliable method for assessing immunogenicity in phase 3 clinical trials.

Phase 1 study of trebananib (AMG 386), an angiogenesis targeting angiopoietin-1/2 antagonist, in Japanese patients with advanced solid tumors

PURPOSE

To evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of trebananib (AMG 386)--a first-in-class angiopoietin-1/2 antagonist peptide-Fc fusion protein--in Japanese patients, we conducted a phase 1, dose escalation study.

METHODS

Eligible patients were men or women, aged between 20 and 74 years, who had histologically or cytologically confirmed advanced solid tumors refractory to standard treatment. Trebananib (3, 10, and 30 mg/kg) was administered intravenously over 60 min in weekly cycles.

RESULTS

From June 2009 to April 2010, a total of 18 patients (6 for each dose cohort) were enrolled into the study. Trebananib was tolerated at all dose levels. No dose-limiting toxicities were observed. The most common adverse events were peripheral edema, constipation, fatigue, and pyrexia. Exposure to trebananib appeared to increase according to the dose administered. Serum clearance appeared to be similar across the dose range with the mean terminal-phase half-life ranging from 93.9 to 95.9 h. No neutralizing antibodies were detected. Tumor response was assessed in 18 patients. Of these, one patient with colon cancer in the 3-mg/kg cohort and one with bladder cancer in the 30-mg/kg cohort had partial responses as their best responses. These 2 patients were on treatment at the time of data cutoff (January 17, 2012).

CONCLUSION

Trebananib was tolerated and showed acceptable safety profile in Japanese patients with advanced solid tumors. The pharmacokinetic profiles were similar to those in the previous studies in the United States. Trebananib also showed evidence of durable antitumor activity in some patients.

Three-dimensional power Doppler ultrasound for the study of cervical cancer and precancerous lesions

OBJECTIVE

To evaluate the blood flow characteristics of the cervix in normal women and in women with cervical precancerous lesions or cervical cancer.

METHODS

We studied 165 women with three-dimensional power Doppler ultrasound (3D-PDU), of whom 71 had cervical cancer, 61 had precancerous lesions and 33 were healthy controls. The cervix was manually traced in the stored volumes using 15° rotation steps and the following 3D-PDU indices were calculated: vascularization index (VI), flow index (FI) and vascularization flow index (VFI). These indices were compared among the study groups and were also correlated with features of the precancerous lesions group and cancer group.

RESULTS

The three indices were all statistically significantly higher in the cervical cancer group and precancerous lesions group than in controls (P < 0.001). In addition, significantly higher values of all indices were found in the cervical cancer group than in the precancerous lesions group (P < 0.001). Further analysis according to patient characteristics in the cancer group showed that VI, FI and VFI were not significantly different in relation to grade, histology, presence of positive lymph nodes or lymphovascular space involvement (P > 0.05). However, VI was significantly higher in patients with Stages IIIB-IV cancer than in patients with less advanced disease (P = 0.045). In the cervical cancer group there was a significant positive correlation between 3D-PDU indices and cervical volume.

CONCLUSION

3D-PDU assessment of the cervix reveals significant differences in all indices studied between women with cervical precancerous lesions or cancer and healthy women. In women with cervical cancer, an advanced stage is associated with higher VI, but 3D-PDU indices are not related to other pathological characteristics.

Thrombospondin-1 mimetic peptide ABT-898 affects neovascularization and survival of human endometriotic lesions in a mouse model

Endometriosis is a common cause of pelvic pain and infertility in women, and a common indication for hysterectomy, yet the disease remains poorly diagnosed and ineffectively treated. Because endometriotic lesions require new blood supply for survival, inhibiting angiogenesis could provide a novel therapeutic strategy. ABT-898 mimics the antiangiogenic properties of thrombospondin-1, so we hypothesized that ABT-898 will prevent neovascularization of human endometriotic lesions and that ABT-898 treatment will not affect reproductive outcomes in a mouse model. Endometriosis was induced in BALB/c-Rag2(-/-)Il2rg(-/-) mice by surgical implantation of human endometrial fragments in the peritoneal cavity. Mice received daily injections of ABT-898 for 21 days. Flow cytometry was performed to measure circulating endothelial progenitor cells in peripheral blood. Cytokines were measured in plasma samples. Half of the ABT-898-treated and control mice were euthanized to assess neovascularization of endometriotic lesions, using CD31(+) immunofluorescence. The remaining mice were mated and euthanized at gestation day 12. Endometriotic lesions increased circulating endothelial progenitor cells 13 days after engraftment, relative to baseline. Endometriotic lesions from ABT-898-treated mice exhibited reduced neovascularization, compared with controls, and lesions had fewer CD31(+) microvessels. Chronic treatment with ABT-898 did not lead to any fetal anomalies or affect litter size at gestation day 12, compared with controls. Our results suggest that ABT-898 inhibits neovascularization of human endometriotic lesions without affecting mouse fecundity.

Bioassay-guided isolation of an alkaloid with antiangiogenic and antitumor activities from the extract of Fissistigma cavaleriei root

Fissistigma cavaleriei (Levl) Rehd (Annonaceae) is used as a folklore medicine for treatment of inflammation, arthritis, and tuberculosis by Miao people in China. In the present study, the antiangiogenic activity of F. cavaleriei was investigated. The chorioallantoic membrane of the fertilized hen's egg (CAM assay) was used to determine antiangiogenic activity of the plant extract. Compound (1), a compound with antiangiogenic activity, was isolated by bioassay-guided fractionation from F. cavaleriei for the first time. The structure of compound (1) was elucidated on the basis of spectroscopic methods. Colorimetric COX (ovine) inhibitor screening assay was used to determine its inhibitory effect on COX-1 and COX-2. MTT and Sulforhodamine B assays were used to investigate its cytotoxic effects on tumor cell lines. As a result, compound (1) showed a selectively inhibiting effect on COX-2 and could inhibit the growth of tumor cells in vitro. The antitumor activity of compound (1) was further confirmed by the observation that compound (1) administration significantly inhibited the growth of S-180 cells in mice. Moreover, compound (1) was able to enhance the antitumor activity of doxorubicin in the mice bearing with S-180 cells while combined with doxorubicin. In conclusion, compound (1) is a multi-target molecule and further experimental investigations are needed to determine whether it can be used as a lead molecule for tumor treatment.

Prostate-specific membrane antigen as a potential novel vascular target for treatment of glioblastoma multiforme

CONTEXT

Prostate-specific membrane antigen (PSMA) is expressed in endothelium of vessels in malignant solid tumors but not in normal vessels.

OBJECTIVE

To examine whether neovasculature of glioblastoma multiforme (GBM) expresses PSMA. Design.-After institutional review board approval at Memorial Sloan-Kettering Cancer Center, formalin-fixed paraffin-embedded tissue from 32 patients who underwent a maximally safe neurologic resection during 2004 to 2005 for GBM (World Health Organization criteria) was obtained. We performed immunohistochemical staining on the vessels of the GBM specimens for PSMA expression in tumor endothelium. The tissue samples were also stained for CD31 to verify that the PSMA was staining tumor vessels. The PSMA percent staining was scored: less than 5%, 6% to 25%, 26% to 50%, 51% to 75%, and 76% to 100%. Staining intensity was ranked as follows: 0 (none), 1+ (faint), 2+ (moderately-intense), and 3+ (maximum-intensity).

RESULTS

Immunohistochemical staining on the vessels of 32 paraffin-embedded GBM specimens revealed that all 32 (100%) specimens exhibited staining for PSMA to a variable extent. Of these, 22 of 32 specimens (69%) had more than 51% vascular staining for PSMA. The intensity of staining was 2+ to 3+ in most of the specimens (29 of 32; 91%).

CONCLUSIONS

Prostate-specific membrane antigen is expressed in the vasculature of GBM vessels, thus rendering a potential novel therapeutic vascular target. A clinical trial with a cytotoxin-conjugated antibody to PSMA is planned.

Epidermal growth factor receptor and K-Ras in non-small cell lung cancer-molecular pathways involved and targeted therapies

Lung cancer is currently the leading cause of cancer death in Western nations. Non-small cell lung cancer (NSCLC) represents 80% of all lung cancers, and adenocarcinoma is the predominant histological type. Despite the intensive research carried out on this field and therapeutic advances, the overall prognosis of these patients remains unsatisfactory, with a 5-year overall survival rate of less than 15%. Nowadays, pharmacogenetics and pharmacogenomics represent the key to successful treatment. Recent studies suggest the existence of two distinct molecular pathways in the carcinogenesis of lung adenocarcinoma: one associated with smoking and activation of the K-Ras oncogene and the other not associated with smoking and activation of the epidermal growth factor receptor (EGFR). The K-ras mutation is mainly responsible for primary resistance to new molecules which inhibit tyrosine kinase EGFR (erlotinib and gefitinib) and most of the EGFR mutations are responsible for increased tumor sensitivity to these drugs. This article aims to conduct a systematic review of the literature regarding the molecular pathways involving the EGFR, K-Ras and EGFR targeted therapies in NSCLC tumor behavior.

Opportunities and pitfalls of cancer imaging in clinical trials

Cancer treatment strategies have changed considerably over the past two decades, with increasing emphasis on cancer-specific biological therapies. This situation has led to the incorporation of biomarkers, including those obtained by medical imaging, into trial designs to better understand mechanisms of action and, hopefully, to provide early evidence of treatment efficacy at a molecular or physiological level. Unlike blood tests and tissue samples, an imaging biomarker allows assessment of treatment in the whole tumor, in all tumors in the body, and at multiple time points. This situation has increased the complexity of clinical trials, as each imaging modality has issues related to cost, ease of use, patient compatibility, data analysis, and interpretation. This article reviews strengths and limitations of the current imaging methods available in clinical cancer trials, including MRI, CT, PET, and ultrasonography. The information gained by each test, and the difficulties in acquiring the data and interpreting it are also discussed in order to help researchers plan imaging in clinical trials and interpret data from such studies.

The disintegrin contortrostatin in combination with docetaxel is a potent inhibitor of prostate cancer in vitro and in vivo

BACKGROUND

There are few available treatments for hormone refractory prostate cancer. Through the inhibition of integrins, contortrostatin (CN) effects tumor cell growth directly as well as through the inhibition of angiogenesis. The effect of CN in combination with docetaxel on prostate cancer cell lines in vitro and in vivo is evaluated in the present study.

METHODS

FACS analysis of integrin expression, assessment of CN and docetaxel exposure on viability of plated cancer cells, and scratch test migration analysis were performed on PC-3 prostate cancer cells. CN and docetaxel inhibition of both PC-3 and CWR-22 prostate cancer cell lines were evaluated in a mouse xenograft bone model. Angiogenic activity in tumors were assessed using IHC with antibodies to CD31.

RESULTS

Cell culture experiments indicate that the combination of docetaxel and CN inhibits growth in an additive fashion. FACS analysis of PC-3 cells shows expression of alpha5beta1 and alphavbeta5 integrins, but little expression of the alphavbeta3. CN showed complete inhibition of PC-3 migration in cultures grown on matrigel plates. In mice xenograft bone models, CN with docetaxel showed increased inhibition of both PC-3 and CWR-22 derived tumors. Analysis of treated xenograft tumors showed significantly decreased expression of CD31 indicating suppression of angiogenesis.

Effects of a Chinese herbal health formula, "Gan-Lu-Yin", on angiogenesis

According to the known effects of each ingredient, Gan-Lu-Yin (GLY), a traditional Chinese herbal formula, has the potential to be an antiangiogenic agent. The purpose of this study was to explore the putative effect of GLY on antiangiogenesis. An ethanol extract of GLY was tested on chicken chorioallantoic membrane (CAM) and human umbilical vein endothelial cells (HUVEC) to evaluate the effects of GLY extract on cell proliferation, migration, and tube formation. The results showed that treatment with 1.0 mg/mL of GLY extract could markedly reduce cell migration and in vitro tube formation of HUVEC, and 1.5 mg/mL of GLY extract was sufficient to inhibit proliferation of HUVEC. The expression level of vascular endothelial growth factor (VEGF) of HUVEC was significantly decreased by 1.5 and 2.0 mg/mL of GLY extract. In chicken CAM assay, all tested concentrations of GLY extract were found to reduce the capillary mesh on the CAM of fertilized eggs. The inhibitory effects of GLY extract (1 mg/mL) were also found on tumor cell-induced HUVEC proliferation and tube formation. These observations suggested that GLY extract has an inhibitory effect on angiogenesis, which in turn may prevent tumor growth, and its mechanism might be partially associated with blocking VEGF protein expression of HUVEC.

The experimental design as practical approach to develop and optimize a formulation of peptide-loaded liposomes

To investigate the encapsulation of Print 3G, a peptidic agent that could reduce the angiogenic development of breast tumors, pegylated liposomes used as intravenous vectors were studied and characterized. Recently, the path of liposomes has been explored with success to improve the pharmacological properties of peptidic drugs and to stabilize them. In this study, loaded unilamellar vesicles composed of SPC:CHOL:mPEG2000-DSPE (47:47:6) were prepared by the hydration of lipid film technique. An HPLC method was developed and validated for the determination of Print 3G to calculate its encapsulation efficiency. Observed Print 3G adsorption on different materials employed during liposome preparation (such as glass beads, tubing, and connections for extrusion) led to the modification of the manufacturing method. The freeze-thawing technique was used to enhance the amount of Print 3G encapsulated into blank liposomes prepared using the hydration of lipid film procedure. Many factors may influence peptide entrapment, namely the number of freeze-thawing cycles, the lipid concentration, the peptide concentration, and the mixing time. Consequently, a design of experiments was performed to obtain the best encapsulation efficiency while minimizing the number of experiments. The lipid concentration and the number of freeze-thawing cycles were identified as the positive factors influencing the encapsulation. As a result of the optimization, an optimum was found and encapsulation efficiencies were improved from around 30% to 63%. Liposome integrity was evaluated by photon correlation spectroscopy and freeze-fracture electron microscopy to ensure that the selected formulation possesses the required properties to be a potential candidate for further in vitro and in vivo experiments.