Tumour vasculature targeting agents in hybrid/conjugate drugs

A detailed insight of the tumor targeting using nanocarrier drug delivery system

Human struggle against the deadly disease conditions is continued since ages. The contribution of science and technology in fighting against these diseases cannot be ignored exclusively due to the invention of novel procedure and products, extending their size ranges from micro to nano. Recently nanotechnology has been gaining more consideration for its ability to diagnose and treat different cancers. Different nanoparticles have been used to evade the issues related with conservative anticancer delivery systems, including their nonspecificity, adverse effects and burst release. These nanocarriers including, solid lipid nanoparticles (SLNs), liposomes, nano lipid carriers (NLCs), nano micelles, nanocomposites, polymeric and magnetic nanocarriers, have brought revolutions in antitumor drug delivery. Nanocarriers improved the therapeutic efficacy of anticancer drugs with better accumulation at the specific site with sustained release, improved bioavailability and apoptosis of the cancer cells while bypassing the normal cells. In this review, the cancer targeting techniques and surface modification on nanoparticles are discussed briefly with possible challenges and opportunities. It can be concluded that understanding the role of nanomedicine in tumor treatment is significant, and therefore, the modern progressions in this arena is essential to be considered for a prosperous today and an affluent future of tumor patients.

Non-Cationic RGD-Containing Protein Nanocarrier for Tumor-Targeted siRNA Delivery

Despite the recent successes in siRNA therapeutics, targeted delivery beyond the liver remains the major hurdle for the widespread application of siRNA in vivo. Current cationic liposome or polymer-based delivery agents are restricted to the liver and suffer from off-target effects, poor clearance, low serum stability, and high toxicity. In this study, we genetically engineered a non-cationic non-viral tumor-targeted universal siRNA nanocarrier (MW 26 KDa). This protein nanocarrier consists of three function domains: a dsRNA binding domain (dsRBD) (from human protein kinase R) for any siRNA binding, 18-histidine for endosome escape, and two RGD peptides at the N- and C-termini for targeting tumor and tumor neovasculature. We showed that cloned dual-RGD-dsRBD-18his (dual-RGD) protein protects siRNA against RNases, induces effective siRNA endosomal escape, specifically targets integrin α_vβ₃ expressing cells in vitro, and homes siRNA to tumors in vivo. The delivered siRNA leads to target gene knockdown in the cell lines and tumor xenografts with low toxicity. This multifunctional and biomimetic siRNA carrier is biodegradable, has low toxicity, is suitable for mass production by fermentation, and is serum stable, holding great potential to provide a widely applicable siRNA carrier for tumor-targeted siRNA delivery.

A combination of LightOn gene expression system and tumor microenvironment-responsive nanoparticle delivery system for targeted breast cancer therapy

A light-switchable transgene system called LightOn gene expression system could regulate gene expression with a high on/off ratio under blue light, and have great potential for spatiotemporally controllable gene expression. We developed a nanoparticle drug delivery system (NDDS) to achieve tumor microenvironment-responsive and targeted delivery of diphtheria toxin A (DTA) fragment-encoded plasmids to tumor sites. The expression of DTA was induced by exposure to blue light. Nanoparticles composed of polyethylenimine and vitamin E succinate linked by a disulfide bond, and PEGylated hyaluronic acid modified with RGD peptide, accumulated in tumor tissues and were actively internalized into 4T1 cells via dual targeting to CD44 and α_vβ₃ receptors. The LightOn gene expression system was able to control target protein expression through regulation of the intensity or duration of blue light exposure. In vitro studies showed that light-induced DTA expression reduced 4T1 cell viability and induced apoptosis. Furthermore, the LightOn gene expression system enabled spatiotemporal control of the expression of DTA in a mouse 4T1 tumor xenograft model, which resulted in excellent antitumor effects, reduced tumor angiogenesis, and no systemic toxicity. The combination of the LightOn gene expression system and NDDS may be an effective strategy for treatment of breast cancer.

Synthesis and Investigation of the Role of Benzopyran Dihydropyrimidinone Hybrids in Cell Proliferation, Migration and Tumor Growth

BACKGROUND

Cancer is the second leading cause of mortality worldwide after heart diseases, and lung cancer is the topmost cause of all cancer-related deaths in both sexes. Dihydropyrimidinones (DHPMs) are medicinally important class of molecules with diverse pharmacological activities including anticancer activity. The present study focuses on the molecular hybridization of novel Benzopyran with Dihydropyrimidinone and evaluation of the resulting hybrids for cancer cell proliferation, migration and tumor growth.

METHODS

We have synthesized a focused library of dihydropyrimidinone benzopyran hybrids (compounds 1-11) by joining the aromatic as well as pyran portions of the benzopyran core with dihydropyrimidinone. All the synthesized hybrid molecules were evaluated for their cytotoxic activities against a panel of four human cancer cell lines of diverse tissue origin, viz: A549 (lung carcinoma), MCF7 (mammary gland adenocarcinoma), HCT-116 (colorectal carcinoma), and PANC-1 (pancreatic duct carcinoma) with the help of MTT cell viability assay. A structure-activity relationship was made on the basis of IC50 values of different hybrids. Effect on cell proliferation was examined through colony formation assay, reactive oxygen species generation and mitochondrial membrane potential studies. Wound healing assays and cell scattering assays were employed to check the effect on cell migration. Western blotting experiments were performed to find out the molecular mechanism of action and anti-tumor studies were carried out to evaluate the in vivo efficacy of the selected lead molecule.

RESULTS

Two types of novel hybrids were synthesized efficiently from benzopyran aldehydes, ethylacetoacetate and urea under heteropolyacid catalysis. Compound 3 was found to be the most potent hybrid among the synthesized compounds with consistent cytotoxic activities against four human cancer cell lines (IC50 values: 0.139 - 2.32 μM). Compound 3 strongly inhibited proliferation abilities of A549 cells in colony formation assay. Compound 3 exerted oxidative stress-mediated mitochondrial dysfunction, in which mitochondrial reactive oxygen species (ROS) generation as a mechanism of its anti-proliferative effects was analysed. Further, the molecule abrogated migration and cell scattering properties of aggressive PANC-1 cells. Mechanistic studies revealed that compound 3 modulated NF-kB expression and its downstream oncogenic proteins involved in cancer cell proliferation and invasion. Finally, compound 3 confirmed its in vivo anti-tumor efficacy; there observed 41.87% tumor growth inhibition at a dose of 30 mg/kg/body weight against a mouse model of Ehrlich solid tumor.

CONCLUSION

Our study unravels a potential anticancer lead (compound 3) from DHPMs that have opened up new research avenues for the development of promising anticancer therapeutic agents.

Flow-Responsive Vascular Endothelial Growth Factor Receptor-Protein Kinase C Isoform Epsilon Signaling Mediates Glycolytic Metabolites for Vascular Repair

AIMS

Hemodynamic shear stress participates in maintaining vascular redox status. Elucidating flow-mediated endothelial metabolites enables us to discover metabolic biomarkers and therapeutic targets. We posited that flow-responsive vascular endothelial growth factor receptor (VEGFR)-protein kinase C isoform epsilon (PKCɛ)-6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) signaling modulates glycolytic metabolites for vascular repair.

RESULTS

Bidirectional oscillatory flow (oscillatory shear stress [OSS]: 0.1 ± 3 dyne·cm-2 at 1 Hz) upregulated VEGFR-dependent PKCɛ expression to a greater degree than did unidirectional pulsatile flow (pulsatile shear stress [PSS]: 23 ± 8 dyne·cm-2 at 1 Hz) in human aortic endothelial cells (p < 0.05, n = 3). PSS and OSS further upregulated PKCɛ-dependent PFKFB3 expression for glycolysis (p < 0.05, n = 4). Constitutively active PKCɛ increased, whereas dominant-negative PKCɛ reduced both basal and maximal extracellular acidification rates for glycolytic flux (p < 0.01, n = 4). Metabolomic analysis demonstrated an increase in PKCɛ-dependent glycolytic metabolite, dihydroxyacetone (DHA), but a decrease in gluconeogenic metabolite, aspartic acid (p < 0.05 vs. control, n = 6). In a New Zealand White rabbit model, both PKCɛ and PFKFB3 immunostaining was prominent in the PSS- and OSS-exposed aortic arch and descending aorta. In a transgenic Tg(flk-1:EGFP) zebrafish model, GATA-1a morpholino oligonucleotide injection (to reduce viscosity-dependent shear stress) impaired vascular regeneration after tail amputation (p < 0.01, n = 20), which was restored with PKCɛ messenger RNA (mRNA) rescue (p < 0.05, n = 5). As a corollary, siPKCɛ inhibited tube formation and vascular repair, which were restored by DHA treatment in our Matrigel and zebrafish models. Innovation and Conclusion: Flow-sensitive VEGFR-PKCɛ-PFKFB3 signaling increases the glycolytic metabolite, dihydroxyacetone, to promote vascular repair. Antioxid. Redox Signal. 28, 31-43.

Podophyllotoxin derivatives as an excellent anticancer aspirant for future chemotherapy: A key current imminent needs

Cancer is one of the leading groups of threatened caused by abnormal state cell growth and second leading diseases involved in the major global death. To treat this, research looking for promising anticancer drugs from natural resource, or synthesized novel molecules by diverse group of scientists worldwide. Currently, drugs get into clinical practices and showing side effects with target actions which in turn leading to multidrug resistance unknowingly. Podophyllotoxin, a naturally occurring lignan and with hybrids have become one of the most attractive subjects due to their broad spectrum of pharmacological activities. Podophyllotoxin derivatives have been the centre of attention of extensive chemical amendment and pharmacological investigation in modern decades. Mainly, the innovation of the semi-synthetic anticancer drugs etoposide and teniposide has stimulated prolonged research interest in this structural phenotype. The present review focuses mainly onnew anticancer drugs from podophyllotoxin analogs, mechanism of action and their structure-activity relationships (SAR) as potential anticancer candidates for future discovery of suitable drug candidates.

Monitoring Tumor Response to Antivascular Therapy Using Non-Contrast Intravoxel Incoherent Motion Diffusion-Weighted MRI

Antivascular therapy is a promising approach to the treatment of non-small cell lung cancer (NSCLC), where an imaging modality capable of longitudinally monitoring treatment response could provide early prediction of the outcome. In this study, we sought to investigate the feasibility of using intravoxel incoherent motion (IVIM) diffusion MRI to quantitatively assess the efficacy of the treatments of a vascular-disrupting agent CA4P or its combination with bevacizumab on experimental NSCLC tumors. CA4P caused a strong but reversible effect on tumor vasculature; all perfusion-related parameters-D*, f, fD*, and K^trans-initially showed a decrease of 30% to 60% at 2 hours and then fully recovered to baseline on day 2 for CA4P treatment or on days 4 to 8 for CA4P + bevacizumab treatment; the diffusion coefficient in tumors decreased initially at 2 hours and then increased from day 2 to day 8. We observed a good correlation between IVIM parameters and dynamic contrast-enhanced MRI (DCE-MRI; K^trans). We also found that the relative change in f and fD* at 2 hours correlated well with changes in tumor volume on day 8. In conclusion, our results suggest that IVIM is a promising alternative to DCE-MRI for the assessment of the change in tumor perfusion as a result of antivascular agents and can be used to predict the efficacy of antivascular therapies without the need for contrast media injection. Cancer Res; 77(13); 3491-501. ©2017 AACR.

Marsdeniae tenacissimae extract (MTE) suppresses cell proliferation by attenuating VEGF/VEGFR2 interactions and promotes apoptosis through regulating PKC pathway in human umbilical vein endothelial cells

Marsdeniae tenacissimae extract (MTE), commonly known as Xiao-Ai-Ping in China, is a traditional Chinese herb medicine capable of inhibiting proliferation and metastasis and boosting apoptosis in various cancer cells. However, little is known about the contribution of MTE towards tumor angiogenesis and the underlying mechanism. The present study aimed to evaluate the effects of MTE on the proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) and the molecular mechanism. 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenyl)-2-(4-sulfopheny)-2H-tetrazolium, inner salt (MTS) and PI-stained flow cytometry assays revealed that MTE dose-dependently reduced the proliferation of HUVECs by arresting cell cycle at S phase (P < 0.05). Annexin V-FITC/PI-stained flow cytometry confirmed that MTE (160 μL·L^-1) enhanced the apoptosis of HUVECs significantly (P < 0.001). Real-time quantitative RT-PCR and Western blot analyses showed an increase in Bax expression and a sharply decline in Bcl-2 expression; caspase-3 was activated simultaneously in a dose-dependent manner (P < 0.05). Further study observed the dose-dependent down-regulation of vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2), P2Y6 receptor (P2Y6R), and chemokine (C-C motif) ligand 2 (CCL-2), along with the activation of PKC Δ and up-regulation of p53 in a dose-dependent manner in MTE-treated selected cells (P < 0.05). Collectively, the results from the present study suggested that MTE suppressed the proliferation by attenuating CCL-2-mediated VEGF/VEGFR2 interactions and promoted the apoptosis through PKCΔ-induced p53-dependent mitochondrial pathway in HUVECs, supporting that MTE may be developed as a potent anti-cancer medicine.

Synthesis of Novel c(AmpRGD)-Sunitinib Dual Conjugates as Molecular Tools Targeting the αvβ3 Integrin/VEGFR2 Couple and Impairing Tumor-Associated Angiogenesis

On the basis of a previously discovered anti-α_Vβ₃ integrin peptidomimetic (c(AmpRGD)) and the clinically approved antiangiogenic kinase inhibitor sunitinib, three novel dual conjugates were synthesized (compounds 1-3), featuring the covalent and robust linkage between these two active modules. In all conjugates, the ligand binding competence toward α_Vβ₃ (using both isolated receptors and α_Vβ₃-overexpressing endothelial progenitor EP cells) and the kinase inhibitory activity (toward both isolated kinases and EPCs) remained almost untouched and comparable to the activity of the single active units. Compounds 1-3 showed interesting antiangiogenesis properties in an in vitro tubulogenic assay; furthermore, dimeric-RGD conjugate 3 strongly inhibited in vivo angiogenesis in Matrigel plug assays in FVB mice. These results offer proof-of-concept of how the covalent conjugation of two angiogenesis-related small modules may result in novel and stable molecules, which impair tumor-related angiogenesis with equal or even superior ability as compared to the single modules or their simple combinations.

Current Advances of Tubulin Inhibitors in Nanoparticle Drug Delivery and Vascular Disruption/Angiogenesis

Extensive research over the last decade has resulted in a number of highly potent tubulin polymerization inhibitors acting either as microtubule stabilizing agents (MSAs) or microtubule destabilizing agents (MDAs). These inhibitors have potent cytotoxicity against a broad spectrum of human tumor cell lines. In addition to cytotoxicity, a number of these tubulin inhibitors have exhibited abilities to inhibit formation of new blood vessels as well as disrupt existing blood vessels. Tubulin inhibitors as a vascular disrupting agents (VDAs), mainly from the MDA family, induce rapid tumor vessel occlusion and massive tumor necrosis. Thus, tubulin inhibitors have become increasingly popular in the field of tumor vasculature. However, their pharmaceutical application is halted by a number of limitations including poor solubility and toxicity. Thus, recently, there has been considerable interests in the nanoparticle drug delivery of tubulin inhibitors to circumvent those limitations. This article reviews recent advances in nanoparticle based drug delivery for tubulin inhibitors as well as their tumor vasculature disruption properties.

Tunable release of chemotherapeutic and vascular disrupting agents from injectable fiber fragments potentiates combination chemotherapy

Cancer progression and metastasis relies much on vasculature networks in tumor microenvironment, and the combination treatment with chemotherapeutic drugs and vascular disrupting agents represents apparent clinical benefits. In the current study, fiber fragments with loadings of hydroxycamptothecin (HCPT) or combretastatin A-4 (CA4) were proposed for tumor inhibition and blood vessel disruption after local administration in tumors. To address challenges in balancing the disruption of tumor vessels and intratumoral uptake of chemotherapeutic agents, this study is focus on release tuning of HCPT and CA4 from the fiber fragment mixtures. Hydroxypropyl-β-cyclodextrin (HPCD) was blended at ratios from 0 to 10% into CA4-loaded fiber fragments (Fc) to modulate CA4 release durations from 0.5 to 24days, and HCPT-loaded fiber fragments (Fh) indicated a sustained release for over 35days. In vitro cytotoxicity tests indicated a sequential inhibition on the endothelial and tumor cell growth, and the growth inhibition of tumor cells was more significant after treatment with mixtures of Fh and Fc containing 2% HPCD (Fc2) than that of other mixtures. In an orthotopic breast tumor model, compared with those of free CA4, or Fc with a fast or slow release of CA4, Fh/Fc mixtures with CA4 release durations from 2 to 12days indicated a lower tumor growth rate, a prolonged animal survival, a lower vessel density in tumors, and a less significant tumor metastasis. In addition, the tumor cell proliferation rate, hypoxia-inducible factor-1α expression within tumors, and the number of surface metastatic nodules in lungs were significantly lower after treatment with Fh/Fc2 mixtures with a CA4 release duration of 5days than those of other mixtures. It demonstrates the advantages of fiber fragment mixtures in independently modulating the release of multiple drugs and the essential role of release tuning of chemotherapeutic drugs and vascular disrupting agents in improving the therapeutic efficacy.

Synergistic active targeting of dually integrin αvβ3/CD44-targeted nanoparticles to B16F10 tumors located at different sites of mouse bodies

Conventional enhanced permeation and retention (EPR) mediates the effects of many drugs, including the accumulation of nanocarriers at tumor sites, but its efficiency remains low. In this study, this limitation was overcome by developing a dual-targeting delivery system based on hyaluronan (HA, a major ligand of CD44) and tetraiodothyroacetic acid (tetrac, a specific ligand of αvβ3), which was exploited to carry docetaxel (DTX) for the synergistic active targeting to tumors. First, a tetrac-HA (TeHA) conjugate was synthesized and grafted onto the surfaces of solid lipid nanoparticles (SLNs) (TeHA-SLNs/DTX), with a high encapsulation efficiency of >91.6%. The resulting SLNs exhibited an approximately toroid morphology revealed using TEM. The cellular uptake and cytotoxicity of various formulations on CD44/αvβ3-enriched B16F10 cells were then assessed, and both results confirmed the selective uptake and high cytotoxicity of the TeHA-SLNs/DTX in a TeHA-dependent manner. In vivo imaging and vessel distribution tests revealed the efficiency of synergistic active targeting was higher than that of EPR-mediated passive targeting by the TeHA-SLNs to αvβ3-expressing tumor blood vessels and CD44-expressing tumor cells via selective targeting. Finally, in both xenograft tumor mice and in situ lung metastasis tumor mice, tumor growth was significantly inhibited by TeHA-SLNs/DTX. Therefore, TeHA-SLNs are an efficient system for the dual-targeted delivery of drugs to treat cancer in vivo.

Deciphering the anti-angiogenic effect of endostatin/cyclophosphamide to normalize tumor micrangium through notch signaling pathway in colon cancer

Background

The invasion of colon cancer is associated with the tumor angiogenesis. Endostatin is an important anti-angiogenic agent, and the additive effect of endostatin with a chemotherapeutic agent, cyclophosphamide, on micrangium has not been established.

Methods

Male BALB/c strain nude mice were injected with human colorectal carcinoma cells (HCT-116). The mice were divided into four groups (n = 15, each group) and were treated with different concentrations of endostatin (15, 10, and 5 mg/kg/day), cyclophosphamide (20, 10, and 5 mg/kg/day), and combination of endostatin/cyclophosphamide (15 + 20, 15 + 10, and 15 + 5 mg/kg/day). The tumor inhibition rate was evaluated, followed by the quantification of messenger ribonucleic acid (mRNA) and protein expression of notch signaling components NOTCH-1, NOTCH-3, NOTCH-4, JAG-1, DLL-4, Hes-1, and Hey-1 using quantitative polymerase chain reaction (qPCR). The protein expression of NOTCH-3, JAG-1, and DLL-4 was confirmed using western blotting. Microvessel density (MVD) was evaluated to detect micrangium following the treatment.

Results

The endostatin/cyclophosphamide-treated samples exhibited an additive effect on the tumor inhibition rate and the microvessel count. NOTCH-1, NOTCH-3, NOTCH-4, JAG-1, Hes-1, and Hey-1 expression levels were highly correlated and downregulated in the treated samples, whereas DLL-4 expression was upregulated that accounted for its anti-angiogenic property.

Conclusions

The combination treatment of colon cancer with endostatin and a chemotherapeutic agent, cyclophosphamide proves to be an efficient therapeutic strategy to inhibit the rapid vasculature formation confirmed by the differential expression of notch signaling components.

An overview of molecular hybrids in drug discovery

INTRODUCTION

The hybridization of biologically active molecules is a powerful tool for drug discovery used to target a variety of diseases. It offers the prospect of better drugs for the treatment of a number of illnesses including cancer, malaria, tuberculosis and AIDS. Hybrid drugs can provide combination therapies in a single multi-functional agent and, by doing so, be more specific and powerful than conventional classic treatments. This research field is in great expansion and attracts many researchers worldwide.

AREA COVERED

This review covers the main research published between early 2013 to mid-2015 and takes into account several previous reviews on the subject. Its intention is to showcase the most recent advances reported towards the development of molecular hybrids in drug discovery. Particular attention is given to anticancer hybrids throughout the review.

EXPERT OPINION

Current advances show that molecular hybrids of biologically active molecules can lead to powerful therapeutics. Natural products play a key role in this field. It is also believed that toxin hybrids present a great opportunity for future progress and should be further explored. Furthermore, the synthesis of hybrid organometallics should be systematically studied as it can lead to potent drugs. The crucial requirement for growth still remains the efficacy of synthesis. Hence, the development of efficient synthetic methods allowing rapid access to diverse series of hybrids must be further investigated by researchers.

A new target ligand Ser-Glu for PEPT1-overexpressing cancer imaging

Nanoparticles functionalized with active target ligands have been widely used for tumor-specific diagnosis and therapy. The target ligands include antibodies, peptides, proteins, small molecules, and nucleic acid aptamers. Here, we utilize dipeptide Ser–Glu (DIP) as a new ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for pancreatic cancer target imaging. We demonstrate that in the first step, Ser–Glu-conjugated NPs (NPs-DIP) efficiently bind to AsPC-1 and in the following NPs-DIP are internalized into AsPC-1 in vitro. The peptide transporter 1 inhibition experiment reveals that the targeting effects mainly depend on the specific binding of DIP to peptide transporter 1, which is remarkably upregulated in pancreatic cancer cells compared with varied normal cells. Furthermore, NPs-DIP specifically accumulate in the site of pancreatic tumor xenograft and are further internalized into the tumor cells in vivo after intravenous administration, indicating that DIP successfully enhanced nanoparticles internalization efficacy into tumor cells in vivo. This work establishes Ser–Glu to be a new tumor-targeting ligand and provides a promising tool for future tumor diagnostic or therapeutic applications.

AMP-guided tumour-specific nanoparticle delivery via adenosine A1 receptor

Active targeting-ligands have been increasingly used to functionalize nanoparticles for tumour-specific clinical applications. Here we utilize nucleotide adenosine 5'-monophosphate (AMP) as a novel ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for tumour-targeted imaging. We demonstrate that AMP-conjugated NPs (NPs-AMP) efficiently bind to and are following internalized into colon cancer cell CW-2 and breast cancer cell MDA-MB-468 in vitro. RNA interference and inhibitor assays reveal that the targeting effects mainly rely on the specific binding of AMP to adenosine A1 receptor (A1R), which is greatly up-regulated in cancer cells than in matched normal cells. More importantly, NPs-AMP specifically accumulate in the tumour site of colon and breast tumour xenografts and are further internalized into the tumour cells in vivo via tail vein injection, confirming that the high in vitro specificity of AMP can be successfully translated into the in vivo efficacy. Furthermore, NPs-AMP exhibit an active tumour-targeting behaviour in various colon and breast cancer cells, which is positively related to the up-regulation level of A1R in cancer cells, suggesting that AMP potentially suits for more extensive A1R-overexpressing cancer models. This work establishes AMP to be a novel tumour-targeting ligand and provides a promising strategy for future diagnostic or therapeutic applications.

Wogonoside inhibits angiogenesis in breast cancer via suppressing Wnt/β-catenin pathway

Wogonoside, a main flavonoid component derived from the root of Scutellaria baicalensis Georgi, has been reported to have anti-angiogenesis and anti-leukemia activities. However, whether it can inhibit tumor angiogenesis is unclear. In this study, we investigate the inhibitory effect of wogonoside on angiogenesis in breast cancer and its underlying mechanisms. ELISA assay shows that wogonoside (25, 50, and 100 µM) decreases the secretion of VEGF in MCF-7 cells by 30.0%, 35.4%, and 40.1%, respectively. We find it inhibits angiogenesis induced by the conditioned media from MCF-7 cells in vitro and in vivo by migration, tube formation, rat aortic ring, and chicken chorioallantoic membrane (CAM) assay. Meanwhile, wogonoside can inhibit the growth and angiogenesis of MCF-7 cells xenografts in nude mice. The reduction of tumor weight can be found both in wogonoside (80 mg/kg) and bevacizumab (20 mg/kg) treated group, and the tumor inhibition rate is 42.1% and 48.7%, respectively. In addition, mechanistic studies demonstrate that wogonoside suppresses the activation of Wnt/β-catenin pathway in MCF-7 cells. Wogonoside (100 µM) decreases the intracellular level of Wnt3a, increases the expression of GSK-3β, AXIN, and promotes the phosphorylation of β-catenin for proteasome degradation significantly. Furthermore, the nuclear accumulation of β-catenin and the DNA-binding activity of β-catenin/TCF/Lef complex are inhibited by 49.2% and 28.7%, respectively, when treated with 100 µM wogonoside. Taken together, our findings demonstrate that wogonoside is a potential inhibitor of tumor angiogenesis and can be developed as a therapeutic agent for breast cancer. © 2015 Wiley Periodicals, Inc.

Monitoring Combretastatin A4-induced tumor hypoxia and hemodynamic changes using endogenous MR contrast and DCE-MRI

PURPOSE

To benchmark MOBILE (Mapping of Oxygen By Imaging Lipid relaxation Enhancement), a recent noninvasive MR method of mapping changes in tumor hypoxia, electron paramagnetic resonance (EPR) oximetry, and dynamic contrast-enhanced MRI (DCE-MRI) as biomarkers of changes in tumor hemodynamics induced by the antivascular agent combretastatin A4 (CA4).

METHODS

NT2 and MDA-MB-231 mammary tumors were implanted subcutaneously in FVB/N and nude NMRI mice. Mice received 100 mg/kg of CA4 intraperitoneally 3 hr before imaging. The MOBILE sequence (assessing R1 of lipids) and the DCE sequence (assessing K(trans) hemodynamic parameter), were assessed on different cohorts. pO2 changes were confirmed on matching tumors using EPR oximetry consecutive to the MOBILE sequence. Changes in tumor vasculature were assessed using immunohistology consecutive to DCE-MRI studies.

RESULTS

Administration of CA4 induced a significant decrease in lipids R1 (P = 0.0273) on pooled tumor models and a reduction in tumor pO2 measured by EPR oximetry. DCE-MRI also exhibited a significant drop of K(trans) (P < 0.01) that was confirmed by immunohistology.

CONCLUSION

MOBILE was identified as a marker to follow a decrease in oxygenation induced by CA4. However, DCE-MRI showed a higher dynamic range to follow changes in tumor hemodynamics induced by CA4.

Nanoscale drug delivery for taxanes based on the mechanism of multidrug resistance of cancer

Taxanes are one type of the most extensively used chemotherapeutic agents to treat cancers. However, their clinical use is severely limited by intrinsic and acquired resistance. A diverse variety of mechanisms has been implicated about taxane resistance, such as alterations of drug targets, overexpression of efflux transporters, defective apoptotic machineries, and barriers in drug transport. The deepening understanding of molecular mechanisms of taxane resistance has spawned a number of targets for reversing resistance. However, circumvention of taxane resistance would not only possess therapeutic potential, but also face with clinical challenge, which accelerates the development of optimal nanoscale delivery systems. This review highlights the current understanding on the mechanisms of taxane resistance, and provides a comprehensive analysis of various nanoscale delivery systems to reverse taxane resistance.

Anti-tumor effect of a novel soluble recombinant human endostatin: administered as a single agent or in combination with chemotherapy agents in mouse tumor models

Background

Angiogenesis has become an attractive target in cancer treatment. Endostatin is one of the potent anti-angiogenesis agents. Its recombinant form expressed in the yeast system is currently under clinical trials. Endostatin suppresses tumor formation through the inhibition of blood vessel growth. It is anticipated that combined therapy using endostatin and cytotoxic compounds may exert an additive effect. In the present study, we expressed and purified recombinant human endostatin (rhEndostatin) that contained 3 additional amino acid residues (arginine, glycine, and serine) at the amino-terminus and 6 histidine residues in its carboxyl terminus. The recombinant protein was expressed in E. Coli and refolded into a soluble form in a large scale purification process. The protein exhibited a potent anti-tumor activity in bioassays. Furthermore, rhEndostatin showed an additive effect with chemotherapy agents including cyclophosphamide (CTX) and cisplatin (DDP).

Methods

rhEndostatin cDNA was cloned into PQE vector and expressed in E. Coli. The protein was refolded through dialysis with an optimized protocol. To establish tumor models, nude mice were subcutaneously injected with human cancer cells (lung carcinoma A549, hepatocellular carcinoma QGY-7703, or breast cancer Bcap37). rhEndostatin and/or DDP was administered peritumorally to evaluate the rate of growth inhibition of A549 tumors. For the tumor metastasis model, mice were injected intravenously with mouse melanoma B16 cells. One day after tumor cell injection, a single dose of rhEndostatin, or in combination with CTX, was administered intravenously or at a site close to the tumor.

Results

rhEndostatin reduced the growth of A549, QGY-7703, and Bcap37 xenograft tumors in a dose dependent manner. When it was administered peritumorally, rhEndostatin exhibited a more potent inhibitory activity. Furthermore, rhEndostatin displayed an additive effect with CTX or DDP on the inhibition of metastasis of B16 tumors or growth of A549 tumors.

Conclusion

Soluble rhEndostatin exhibits a potent anti-tumor activity in mouse xenograft models and it also has an additive effect with CTX and DDP, implying possible applications in clinical settings.

Passive versus active tumor targeting using RGD- and NGR-modified polymeric nanomedicines

Enhanced permeability and retention (EPR) and the (over-) expression of angiogenesis-related surface receptors are key features of tumor blood vessels. As a consequence, EPR-mediated passive and Arg-Gly-Asp (RGD) and Asn-Gly-Arg (NGR) based active tumor targeting have received considerable attention in the last couple of years. Using several different in vivo and ex vivo optical imaging techniques, we here visualized and quantified the benefit of RGD- and NGR-based vascular vs EPR-mediated passive tumor targeting. This was done using ∼ 10 nm sized polymeric nanocarriers, which were either labeled with DY-676 (peptide-modified polymers) or with DY-750 (peptide-free polymers). Upon coinjection into mice bearing both highly leaky CT26 and poorly leaky BxPC3 tumors, it was found that vascular targeting did work, resulting in rapid and efficient early binding to tumor blood vessels, but that over time, passive targeting was significantly more efficient, leading to higher overall levels and to more efficient retention within tumors. Although this situation might be different for larger carrier materials, these insights indicate that caution should be taken not to overestimate the potential of active over passive tumor targeting.

TRAIL negatively regulates VEGF-induced angiogenesis via caspase-8-mediated enzymatic and non-enzymatic functions

Solid tumors supply oxygen and nutrients required for angiogenesis by producing vascular endothelial growth factor (VEGF). Thus, inhibitors of VEGF signaling abrogate tumor angiogenesis, resulting in the suppression of tumor growth and metastasis. We here investigated the effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on VEGF-induced angiogenesis. TRAIL inhibited VEGF-induced in vitro angiogenesis of human umbilical vein endothelial cells (HUVECs) and in vivo neovascularization in chicken embryos and mice. TRAIL blocked VEGF-induced angiogenic signaling by inhibiting ERK, Src, FAK, paxillin, Akt, and eNOS. Further, TRAIL blocked intracellular Ca(2+) elevation and actin reorganization in HUVECs stimulated with VEGF, without inhibiting VEGF receptor-2 tyrosine phosphorylation. TRAIL increased caspase-8 activity, without inducing caspase-9/-3 activation and apoptosis. Moreover, TRAIL resulted in cleavage of FAK into FAK-related non-kinase-like fragments in VEGF-stimulated HUVECs, which was blocked by a caspase-8 inhibitor and cellular caspase-8-like inhibitory protein. Biochemical and pharmacological inhibition of caspase-8 and FAK blocked the inhibitory effects of TRAIL on VEGF-stimulated anti-angiogenic signaling and events. In addition, caspase-8 knockdown also suppressed VEGF-mediated signaling and angiogenesis, suggesting that procaspase-8 plays a role of a non-apoptotic modulator in VEGF-induced angiogenic signaling. These results suggest that TRAIL inhibits VEGF-induced angiogenesis by increasing caspase-8 activity and subsequently decreasing non-apoptotic signaling functions of procaspase-8, without inducing caspase-3 activation and endothelial cell cytotoxicity. These data indicate that caspase-8 may be used as an anti-angiogenic drug for solid tumors resistant to TRAIL and anti-tumor drugs.