Anti-angiogenic cancer therapy based on integrin alphavbeta3 antagonism

The roles of templates consisting of amino acids in the synthesis and application of gold nanoclusters

Gold nanoclusters (AuNCs) with low toxicity, high photostability, and facile synthesis have attracted great attention. The ligand is of great significance in stabilizing AuNCs and regulating their properties. Ligands consisting of amino acids (proteins and peptides) are an ideal template for synthesizing applicative AuNCs due to their inherent bioactivity, biocompatibility, and accessibility. In this review, we summarize the correlation of the template consisting of amino acids with the properties of AuNCs by analyzing different peptide sequences. The selection of amino acids can regulate the fluorescence excitation/emission and intensity, size, cell uptake, and light absorption. By analyzing the role played by AuNCs stabilized by proteins and peptides in the application, universal rules and detailed performances of sensors, antibacterial agents, therapeutic reagents, and light absorbers are reviewed. This review can guide the template design and application of AuNCs when selecting proteins and peptides as ligands.

Recent Advances, Challenges, and Future Perspectives of ZnO Nanostructure Materials Towards Energy Applications

In this approach, zinc oxide (ZnO) is a multipurpose substance with remarkable characteristics such as high sensitivity, a large specific area, non-toxicity, excellent compatibility, and a high isoelectric point, which make it attractive for discussion with some limitations. It is the most favorable possible option for the collection of nanostructures in terms of structure and their characteristics. The development of numerous ZnO nanostructure-based electrochemical sensors and biosensors used in health diagnosis, pharmaceutical evaluation, food hygiene, and contamination of the environment monitoring is described, as well as the production of ZnO nanostructures. Nanostructured ZnO has good chemical and temperature durability as an n-type semiconducting material, making it useful in a wide range of uses, from luminous materials to supercapacitors, batteries, solar cells, photocatalysis, biosensors, medicinal devices, and more. When compared to the bulk materials, the nanosized materials have both a higher rate of disintegration and a higher solubility. Furthermore, ZnO nanoparticles are regarded as top contenders for electrochemical sensors due to their strong electrochemical behaviors and electron transmission characteristics. The impact of many factors, including selectivity, sensitivity, detection limit, strength, and structures, arrangements, and their respective functioning processes, has been investigated. This study concentrated a substantial amount of its attention on the recent advancements that have been made in ZnO-based nanoparticles, composites, and modified materials for use in the application areas of energy storage and conversion devices as well as biological applications. Supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, medicinal, and biological systems have been studied. ZnO-based materials are constantly analyzed for their advantages in energy and life science applications.

Engineering Proteins for Cell Entry

Proteins are essential for life, as they participate in all vital processes in the body. In the past decade, delivery of active proteins to specific cells and organs has attracted increasing interest. However, most proteins cannot enter the cytoplasm due to the cell membrane acting as a natural barrier. To overcome this challenge, various proteins have been engineered to acquire cell-penetrating capacity by mimicking or modifying natural shuttling proteins. In this review, we provide an overview of the different types of engineered cell-penetrating proteins such as cell-penetrating peptides, supercharged proteins, receptor-binding proteins, and bacterial toxins. We also discuss some strategies for improving endosomal escape such as pore formation, the proton sponge effect, and hijacking intracellular trafficking pathways. Finally, we introduce some novel methods and technologies for designing and detecting engineered cell-penetrating proteins.

Multifunctional nanoplatforms application in the transcatheter chemoembolization against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has the sixth-highest new incidence and fourth-highest mortality worldwide. Transarterial chemoembolization (TACE) is one of the primary treatment strategies for unresectable HCC. However, the therapeutic effect is still unsatisfactory due to the insufficient distribution of antineoplastic drugs in tumor tissues and the worsened post-embolization tumor microenvironment (TME, e.g., hypoxia and reduced pH). Recently, using nanomaterials as a drug delivery platform for TACE therapy of HCC has been a research hotspot. With the development of nanotechnology, multifunctional nanoplatforms have been developed to embolize the tumor vasculature, creating conditions for improving the distribution and bioavailability of drugs in tumor tissues. Currently, the researchers are focusing on functionalizing nanomaterials to achieve high drug loading efficacy, thorough vascular embolization, tumor targeting, controlled sustained release of drugs, and real-time imaging in the TACE process to facilitate precise embolization and enable therapeutic procedures follow-up imaging of tumor lesions. Herein, we summarized the recent advances and applications of functionalized nanomaterials based on TACE against HCC, believing that developing these functionalized nanoplatforms may be a promising approach for improving the TACE therapeutic effect of HCC.

Ameliorating the antitumor activity of gemcitabine against breast tumor using αvβ3 integrin-targeting lipid nanoparticles

OBJECTIVE

The main objective is to formulate solid lipid nanoparticles conjugated with cyclic RGDfk peptide encapsulated with gemcitabine hydrochloride drug for targeting breast cancer.

SIGNIFICANCE

The hydrophilic nature of gemcitabine hampers passive transport by cell membrane permeation that may lead to drug resistance as it has to enter the cells via nucleoside transporters. The art of encapsulating the drug in nanovesicle and then anchoring it with targeting ligand is one of the present areas of research in cancer chemotherapy.

METHODS

In this study solid lipid nanoparticles were prepared by double emulsification and solvent evaporation method. Cyclic RGDfk and gemcitabine hydrochloride were used as targeting ligand and chemotherapeutic drug, respectively, for targeting breast cancer. The prepared nanoparticles were evaluated for in vitro and in vivo performance to showcase the targeting efficiency and therapeutic benefits of the gemcitabine loaded ligand conjugated nanoparticles.

RESULTS

When compared with gemcitabine (GEM) and GEM loaded nanoparticles (GSLN), the ligand conjugated GEM nanoparticles (cGSLN) showed superior cytotoxicity, apoptosis and inhibition of 3D multicellular spheroids in human breast cancer cells (MDA MB 231). The in vivo tumor regression studies in orthotopic breast cancer induced Balb/C mice showed that cGSLN displayed superior tumor suppression and also the targeting potential of the cGSLN towards induced breast cancer.

CONCLUSION

Prepared nanoformulations showed enhanced anticancer activity in both 2D and 3D cell culture models along with antitumor efficacy in orthotopic breast cancer mouse models.

Functional drug carriers formed by RGD-modified β-CD-HPG for the delivery of docetaxel for targeted inhibition of nasopharyngeal carcinoma cells

In this study, a drug delivery system was prepared by grafting the targeting molecule arginine-glycine-aspartic acid (RGD) onto hyperbranched polyglycerol (HPG)-modified β-cyclodextrin (β-CD-HPG) for the targeted inhibition of nasopharyngeal carcinoma (NPC) cells. The obtained β-CD-HPG-RGD with a relatively small size and low surface charge delivered docetaxel (Doc) effectively and displayed a targeting effect to human NPC HNE-1 cells, as confirmed by confocal laser scanning microscopy and flow cytometry. The in vitro drug release analysis exhibited the controlled drug release kinetics of the β-CD-HPG-RGD/Doc nanomedicine. β-CD-HPG-RGD/Doc effectively inhibited the proliferation of HNE-1 cells and promoted apoptosis. Moreover, its biocompatibility in vitro and in vivo was assessed. The results indicate that the β-CD-HPG-RGD/Doc nanomedicine has potential application in NPC targeting therapy.

Comparative use of CRISPR and RNAi to modulate integrin α3β1 in triple negative breast cancer cells reveals that some pro-invasive/pro-metastatic α3β1 functions are independent of global regulation of the transcriptome

Integrin receptors for the extracellular matrix play critical roles at all stages of carcinogenesis, including tumor growth, tumor progression and metastasis. The laminin-binding integrin α3β1 is expressed in all epithelial tissues where it has important roles in cell survival, migration, proliferation, and gene expression programs during normal and pathological tissue remodeling. α3β1 signaling and adhesion functions promote tumor growth and metastasis in a number of different types of cancer cells. Previously, we used RNA interference (RNAi) technology to suppress the expression of the ITGA3 gene (encoding the α3 subunit) in the triple-negative breast cancer cell line, MDA-MB-231, thereby generating variants of this line with reduced expression of integrin α3β1. This approach revealed that α3β1 promotes pro-tumorigenic functions such as cell invasion, lung metastasis, and gene regulation. In the current study, we used CRISPR technology to knock out the ITGA3 gene in MDA-MB-231 cells, thereby ablating expression of integrin α3β1 entirely. RNA-seq analysis revealed that while the global transcriptome was altered substantially by RNAi-mediated suppression of α3β1, it was largely unaffected following CRISPR-mediated ablation of α3β1. Moreover, restoring α3β1 to the latter cells through inducible expression of α3 cDNA failed to alter gene expression substantially, suggesting that use of CRISPR to abolish α3β1 led to a decoupling of the integrin from its ability to regulate the transcriptome. Interestingly, both cell invasion in vitro and metastatic colonization in vivo were reduced when α3β1 was abolished using CRISPR, as we observed previously using RNAi to suppress α3β1. Taken together, our results show that pro-invasive/pro-metastatic roles for α3β1 are not dependent on its ability to regulate the transcriptome. Moreover, our finding that use of RNAi versus CRISPR to target α3β1 produced distinct effects on gene expression underlines the importance of using multiple approaches to obtain a complete picture of an integrin’s functions in cancer cells.

Current Perspectives on Therapies, Including Drug Delivery Systems, for Managing Glioblastoma Multiforme

Glioblastoma multiforme (GBM), a standout among the most dangerous class of central nervous system (CNS) cancer, is most common and is an aggressive malignant brain tumor in adults. In spite of developments in modality therapy, it remains mostly incurable. Consequently, the need for novel systems, strategies, or therapeutic approaches for enhancing the assortment of active agents meant for GBM becomes an important criterion. Currently, cancer research focuses mainly on improving the treatment of GBM via diverse novel drug delivery systems. The treatment options at diagnosis are multimodal and include radiation therapy. Moreover, significant advances in understanding the molecular pathology of GBM and associated cell signaling pathways have opened opportunities for new therapies. Innovative treatment such as immunotherapy also gives hope for enhanced survival. The objective of this work was to collect and report the recent research findings to manage GBM. The present review includes existing novel drug delivery systems and therapies intended for managing GBM. Reported novel drug delivery systems and diverse therapies seem to be precise, secure, and relatively effective, which could lead to a new track for the obliteration of GBM.

A combined "eat me/don't eat me" strategy based on extracellular vesicles for anticancer nanomedicine

A long-term and huge challenge in nanomedicine is the substantial uptake and rapid clearance mediated by the mononuclear phagocyte system (MPS), which enormously hinders the development of nanodrugs. Inspired by the natural merits of extracellular vesicles, we therefore developed a combined "eat me/don't eat me" strategy in an effort to achieve MPS escape and efficient drug delivery. Methodologically, cationized mannan-modified extracellular vesicles derived from DC2.4 cells were administered to saturate the MPS (eat me strategy). Then, nanocarriers fused to CD47-enriched exosomes originated from human serum were administered to evade phagocytosis by MPS (don't eat me strategy). The nanocarriers were also loaded with antitumor drugs and functionalized with a novel homing peptide to promote the tumour tissue accumulation and cancer cell uptake (eat me strategy). The concept was proven in vitro as evidenced by the reduced endocytosis of macrophages and enhanced uptake by tumour cells, whereas prolonged circulation time and increased tumour accumulation were demonstrated in vivo. Specially, the strategy induced a 123.53% increase in tumour distribution compared to conventional nanocarrier. The study both shed light on the challenge overcoming of phagocytic evasion and provided a strategy for significantly improving therapeutic outcomes, potentially permitting active drug delivery via targeted nanomedicines.

Peptide-Drug Conjugates and Their Targets in Advanced Cancer Therapies

Cancer became recently the leading cause of death in industrialized countries. Even though standard treatments achieve significant effects in growth inhibition and tumor elimination, they cause severe side effects as most of the applied drugs exhibit only minor selectivity for the malignant tissue. Hence, specific addressing of tumor cells without affecting healthy tissue is currently a major desire in cancer therapy. Cell surface receptors, which bind peptides are frequently overexpressed on cancer cells and can therefore be considered as promising targets for selective tumor therapy. In this review, the benefits of peptides as tumor homing agents are presented and an overview of the most commonly addressed peptide receptors is given. A special focus was set on the bombesin receptor family and the neuropeptide Y receptor family. In the second part, the specific requirements of peptide-drug conjugates (PDC) and intelligent linker structures as an essential component of PDC are outlined. Furthermore, different drug cargos are presented including classical and recent toxic agents as well as radionuclides for diagnostic and therapeutic approaches. In the last part, boron neutron capture therapy as advanced targeted cancer therapy is introduced and past and recent developments are reviewed.

Targeting Tumors Using Peptides

To penetrate solid tumors, low molecular weight (Mw < 10 KDa) compounds have an edge over antibodies: their higher penetration because of their small size. Because of the dense stroma and high interstitial fluid pressure of solid tumors, the penetration of higher Mw compounds is unfavored and being small thus becomes an advantage. This review covers a wide range of peptidic ligands—linear, cyclic, macrocyclic and cyclotidic peptides—to target tumors: We describe the main tools to identify peptides experimentally, such as phage display, and the possible chemical modifications to enhance the properties of the identified peptides. We also review in silico identification of peptides and the most salient non-peptidic ligands in clinical stages. We later focus the attention on the current validated ligands available to target different tumor compartments: blood vessels, extracelullar matrix, and tumor associated macrophages. The clinical advances and failures of these ligands and their therapeutic conjugates will be discussed. We aim to present the reader with the state-of-the-art in targeting tumors, by using low Mw molecules, and the tools to identify new ligands.

Integrin β3 promotes cardiomyocyte proliferation and attenuates hypoxia-induced apoptosis via regulating the PTEN/Akt/mTOR and ERK1/2 pathways

Objective: Integrin β3 is one of the main integrin heterodimer receptors on the surface of cardiac myocytes. Our previous studies showed that hypoxia induces apoptosis and increases integrin β3 expression in cardiomyocytes. However, the exact mechanism by which integrin β3 protects against apoptosis remains unclear. Hence, the present investigation aimed to explore the mechanism of integrin β3 in cardiomyocyte proliferation and hypoxia-induced cardiomyocyte apoptosis. Methods: Stable cells and in vivo acute and chronic heart failure rat models were generated to reveal the essential role of integrin β3 in cardiomyocyte proliferation and apoptosis. Western blotting and immunohistochemistry were employed to detect the expression of integrin β3 in the stable cells and rat cardiac tissue. Flow cytometer was used to investigate the role of integrin β3 in hypoxia-induced cardiomyocyte apoptosis. Confocal microscopy was used to detect the localization of integrin β3 and integrin αv in cardiomyocytes. Results: A cobaltous chloride-induced hypoxic microenvironment stimulated cardiomyocyte apoptosis and increased integrin β3 expression in H9C2 cells, AC16 cells, and cardiac tissue from acute and chronic heart failure rats. The overexpression of integrin β3 promoted cardiomyocyte proliferation, whereas silencing integrin β3 expression resulted in decreased cell proliferation in vitro. Furthermore, knocking down integrin β3 expression using shRNA or the integrin β3 inhibitor cilengitide exacerbated cobaltous chloride-induced cardiomyocyte apoptosis, whereas overexpression of integrin β3 weakened cobaltous chloride-induced cardiomyocytes apoptosis. We found that integrin β3 promoted cardiomyocytes proliferation through the regulation of the PTEN/Akt/mTOR and ERK1/2 signaling pathways. In addition, we found that knockdown of integrin αv or integrin β1 weakened the effect of integrin β3 in cardiomyocyte proliferation. Conclusion: Our findings revealed the molecular mechanism of the role of integrin β3 in cardiomyocyte proliferation and hypoxia-induced cardiomyocyte apoptosis, providing new insights into the mechanisms underlying myocardial protection.

A review on ZnO nanostructured materials: energy, environmental and biological applications

Zinc oxide (ZnO) is an adaptable material that has distinctive properties, such as high-sensitivity, large specific area, non-toxicity, good compatibility and a high isoelectric point, which favours it to be considered with a few exceptions. It is the most desirable group of nanostructure as far as both structure and properties. The unique and tuneable properties of nanostructured ZnO shows excellent stability in chemically as well as thermally stable n-type semiconducting material with wide applications such as in luminescent material, supercapacitors, battery, solar cells, photocatalysis, biosensors, biomedical and biological applications in the form of bulk crystal, thin film and pellets. The nanosized materials exhibit higher dissolution rates as well as higher solubility when compared to the bulk materials. This review significantly focused on the current improvement in ZnO-based nanomaterials/composites/doped materials for the application in the field of energy storage and conversion devices and biological applications. Special deliberation has been paid on supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, biomedical and biological applications. Finally, the benefits of ZnO-based materials for the utilizations in the field of energy and biological sciences are moreover consistently analysed.

γ-AApeptides as a New Strategy for Therapeutic Development

A new class of peptidomimetics termed as "γ-AApeptides" was recently developed by our group. Similar to other peptidomimetics, γ-AApeptides are resistant to proteolytic degradation, and possess limitless potential to introduce chemically diverse functional groups. γ-AApeptides have shown great promise in biomedical applications. In this article, we will review a few examples of γ-AApeptides with biological potential. Certain γ-AApeptides can permeate cell membranes and therefore they can be used as potential drug carrier. γ-AApeptides can also bind to HIV RNA with high specificity and affinity, suggesting their potential application as anti-HIV agents. Moreover, they can mimic host-defense peptides and display potent and broad-spectrum activity towards a range of drug-resistant bacterial pathogens. They are also potential anti-cancer agents. For instance, they have shown great promise in targeted imaging of tumor in mouse model, and they are also capable of disrupting p53/DNA interactions, and thus antagonize STAT3 signaling pathway. Recently, from combinatorial screening, γ-AApeptides are identified to inhibit Aβ peptide aggregation, and thus they can be developed into potential anti- Alzheimer's disease agent.

Role of Integrins in Resistance to Therapies Targeting Growth Factor Receptors in Cancer

Integrins contribute to cancer progression and aggressiveness by activating intracellular signal transduction pathways and transducing mechanical tension forces. Remarkably, these adhesion receptors share common signaling networks with receptor tyrosine kinases (RTKs) and support their oncogenic activity, thereby promoting cancer cell proliferation, survival and invasion. During the last decade, preclinical studies have revealed that integrins play an important role in resistance to therapies targeting RTKs and their downstream pathways. A remarkable feature of integrins is their wide-ranging interconnection with RTKs, which helps cancer cells to adapt and better survive therapeutic treatments. In this context, we should consider not only the integrins expressed in cancer cells but also those expressed in stromal cells, since these can mechanically increase the rigidity of the tumor microenvironment and confer resistance to treatment. This review presents some of these mechanisms and outlines new treatment options for improving the efficacy of therapies targeting RTK signaling.

ANGPTL3: a novel biomarker and promising therapeutic target

Angiopoietin-like protein 3 (ANGPTL3) belongs to a multifunctional secreted protein that mainly expresses in the liver, and is regulated by numerous post-translational modifications, including multiple cleavage and glycosylation. Accumulating evidences have revealed that ANGPTL3 plays a critical role in both biological processes, such as lipid metabolism, angiogenesis and haematopoietic function and pathological changes, including atherosclerosis, carcinogenesis, nephrotic syndrome, diabetes, liver diseases and so on. Thus, ANGPTL3 may serve as a potential biomarker in these diseases. Furthermore, ANGPTL3 signalling pathways including LXR/ANGPTL3, thyroid hormone/ANGPTL3, insulin/ANGPTL3 and leptin/ANGPTL3 are also involved in physiological and pathological processes. Some biological ANGPTL3 inhibitors, chemical drugs and traditional Chinese medicine exert beneficial effects by targeting ANGPTL3 directly or indirectly. Therefore, elucidating the effects and underlying mechanisms of ANGPTL3 is essential to develop promising strategies in the diagnosis and treatment of related diseases.

Non-genomic Actions of Thyroid Hormones Regulate the Growth and Angiogenesis of T Cell Lymphomas

T-cell lymphomas (TCL) are a heterogeneous group of aggressive clinical lymphoproliferative disorders with considerable clinical, morphological, immunophenotypic, and genetic variation, including ~10-15% of all lymphoid neoplasms. Several evidences indicate an important role of the non-neoplastic microenvironment in promoting both tumor growth and dissemination in T cell malignancies. Thus, dysregulation of integrin expression and activity is associated with TCL survival and proliferation. We found that thyroid hormones acting via the integrin αvβ3 receptor are crucial factors in tumor microenvironment (TME) affecting the pathophysiology of TCL cells. Specifically, TH-activated αvβ3 integrin signaling promoted TCL proliferation and induced and an angiogenic program via the up-regulation of the vascular endothelial growth factor (VEGF). This was observed both on different TCL cell lines representing the different subtypes of human hematological malignancy, and in preclinical models of TCL tumors xenotransplanted in immunodeficient mice as well. Moreover, development of solid tumors by inoculation of murine TCLs in syngeneic hyperthyroid mice, showed increased tumor growth along with increased expression of cell cycle regulators. The genomic or pharmacological inhibition of integrin αvβ3 decreased VEGF production, induced TCL cell death and decreased in vivo tumor growth and angiogenesis. Here, we review the non-genomic actions of THs on TCL regulation and their contribution to TCL development and evolution. These actions not only provide novel new insights on the endocrine modulation of TCL, but also provide a potential molecular target for its treatment.

From Supramolecular Vesicles to Micelles: Controllable Construction of Tumor-Targeting Nanocarriers Based on Host-Guest Interaction between a Pillar[5]arene-Based Prodrug and a RGD-Sulfonate Guest

The targeting ability, drug-loading capacity, and size of the drug nanocarriers are crucial for enhancing the therapeutic index for cancer therapy. Herein, the morphology and size-controllable fabrication of supramolecular tumor-targeting nanocarriers based on host-guest recognition between a novel pillar[5]arene-based prodrug WP5-DOX and a Arg-Gly-Asp (RGD)-modified sulfonate guest RGD-SG is reported. The amphiphilic WP5-DOX⊃RGD-SG complex with a molar ratio of 5:1 self-assembles into vesicles, whereas smaller-sized micelles can be obtained by changing the molar ratio to 1:3. This represents a novel strategy of controllable construction of supramolecular nanovehicles with different sizes and morphologies based on the same host-guest interactions by using different host-guest ratios. Furthermore, in vitro and in vivo studies reveal that both these prodrug nanocarriers could selectively deliver doxorubicin to RGD receptor-overexpressing cancer cells, leading to longer blood retention time, enhanced antitumor efficacy, and reduced systematic toxicity in murine tumor model, suggesting their potential application for targeted drug delivery.

Computational modeling of synergistic interaction between αVβ3 integrin and VEGFR2 in endothelial cells: Implications for the mechanism of action of angiogenesis-modulating integrin-binding peptides

Cooperation between VEGFR2 and integrin αVβ3 is critical for neovascularization in wound healing, cardiovascular ischemic diseases, ocular diseases, and tumor angiogenesis. In the present study, we developed a rule-based computational model to investigate the potential mechanism by which the Src-induced integrin association with VEGFR2 enhances VEGFR2 activation. Simulations demonstrated that the main function of integrin is to reduce the degradation of VEGFR2 and hence stabilize the activation signal. In addition, receptor synthesis rate and recruitment from internal compartment were found to be sensitive determinants of the activation state of VEGFR2. The model was then applied to simulate the effect of integrin-binding peptides such as tumstatin and cilengitide on VEGFR2 signaling. Further, computational modeling proposed potential molecular mechanisms for the angiogenesis-modulating activity of other integrin-binding peptides. The model highlights the complexity of the crosstalk between αVβ3 integrin and VEGFR2 and the necessity of utilizing models to elucidate potential mechanisms in angiogenesis-modulating peptide therapy.

Formation of Twisted β-Sheet Tapes from a Self-Complementary Peptide Based on Novel Pillararene-GCP Host-Guest Interaction with Gene Transfection Properties

Small peptides capable of assembling into well-defined nanostructures have attracted extensive attention due to their interesting applications as biomaterials. This work reports the first example of a pillararene functionalized with a guanidiniocarbonyl pyrrole (GCP)-conjugated short peptide segment. The obtained amphiphilic peptide 1 spontaneously self-assembles into a supramolecular β-sheet in aqueous solution based on host-guest interaction between pillararene and GCP unit as well as hydrogen-bonding between the peptide strands. Interestingly, peptide 1 at low concentration shows transitions from small particles to "pearl necklace" assemblies, and finally to branched fibers in a time-dependent process. At higher concentration, it directly assembles into twisted β-sheet tapes. Notably, without pillararene moiety, the control peptide A forms α-helix structure with morphology changing from particles to bamboo-like assemblies depending on concentration, indicating a significant role of the pillararene-GCP host-guest interaction for the secondary structure formation. Moreover, peptide 1 can serve as an efficient gene transfection vector.

Hypoxia-targeted gold nanorods for cancer photothermal therapy

Tumor hypoxia is a well-recognized driver of resistance to traditional cancer therapies such as chemotherapy and radiation therapy. We describe development of a new nanoconstruct composed of gold nanorods (GNRs) conjugated to carbonic anhydrase IX (CAIX) antibody that specifically binds to CAIX, a biomarker of hypoxia, to facilitate targeting tumor hypoxic areas for focused photothermal ablation. Physicochemical characterization studies confirmed the size, shape, monodispersity, surface charge, and serum stability of the GNRs. Enzyme-linked immunosorbent assays and cellular binding and uptake studies confirmed successful conjugation of antibody to the GNRs and specificity for CAIX. Near-infrared irradiation of CAIX-overexpressing cells treated with GNR/anti-CAIX resulted in significantly higher cell death than cells treated with control GNRs. In vivo biodistribution studies using hyperspectral imaging and inductively coupled plasma mass spectrometry confirmed intravenous administration results not only in greater accumulation of GNR/anti-CAIX in tumors than control GNRs but also greater penetration into hypoxic areas of tumors. Near-infrared ablation of these tumors showed no tumor regression in the sham-treated group, regression but recurrence in the non-targeted-GNR group, and complete tumor regression in the targeted-GNR group. GNR/anti-CAIX nanoconstructs show promise as hypoxia targeting and photothermal ablation agents for cancer treatment.

On the design principles of peptide-drug conjugates for targeted drug delivery to the malignant tumor site

Cancer is the second leading cause of death affecting nearly one in two people, and the appearance of new cases is projected to rise by >70% by 2030. To effectively combat the menace of cancer, a variety of strategies have been exploited. Among them, the development of peptide–drug conjugates (PDCs) is considered as an inextricable part of this armamentarium and is continuously explored as a viable approach to target malignant tumors. The general architecture of PDCs consists of three building blocks: the tumor-homing peptide, the cytotoxic agent and the biodegradable connecting linker. The aim of the current review is to provide a spherical perspective on the basic principles governing PDCs, as also the methodology to construct them. We aim to offer basic and integral knowledge on the rational design towards the construction of PDCs through analyzing each building block, as also to highlight the overall progress of this rapidly growing field. Therefore, we focus on several intriguing examples from the recent literature, including important PDCs that have progressed to phase III clinical trials. Last, we address possible difficulties that may emerge during the synthesis of PDCs, as also report ways to overcome them.

Comparing the Differential Diagnostic Values of 18F-Alfatide II PET/CT between Tuberculosis and Lung Cancer Patients

Purpose

To compare the differential diagnostic values of ¹⁸F-Alfatide II PET/CT between tuberculosis and lung cancer patients and in patients with sarcoidosis and common inflammation.

Methods

Nine inflammation patients (4 tuberculosis, 3 sarcoidosis, and 2 common inflammation) and 11 lung cancer patients were included in this study. All patients underwent ¹⁸F-FDG and ¹⁸F-Alfatide II PET/CT within 2 weeks, followed by biopsy and surgery. The maximized standard uptake value (SUVmax) and the mean standard uptake value (SUVmean) were evaluated.

Results

The active tuberculosis lesions showed a high accumulation of ¹⁸F-FDG, but varying degrees of accumulation of ¹⁸F-Alfatide II, including negative results. The SUVmax of ¹⁸F-Alfatide II in malignant lesions was significantly higher than that in tuberculosis (4.08 ± 1.51 versus 2.63 ± 1.34, P = 0.0078). Three patients with sarcoidosis showed negative results in ¹⁸F-Alfatide II PET/CT.

Conclusions

The expression of α_Vβ₃ is much lower in tuberculosis as compared to that in lung cancer, and accumulation of ¹⁸F-Alfatide II varied even in lesions of the same patient. The negative results of sarcoidosis patients led to the speculation that α_Vβ₃ was not expressed in those lesions.

Non-invasive assessment of inter-and intrapatient variability of integrin expression in metastasized prostate cancer by PET

Purpose

Due to the high expression of the integrin αvβ3 not only on endothelial cells, but also on mature osteoclasts and prostate cancer cells, imaging of osseous metastases with αvβ3-targeted tracers seems promising. However, little is known about the patterns of αvβ3-expression in metastasized prostate cancer lesions in-vivo. Thus we evaluated the uptake of the αvβ3-specific PET tracer [¹⁸F]Galacto-RGD for assessment of bone metastases in prostate cancer patients.

Results

[¹⁸F]Galacto-RGD PET identified 58/74 bone-lesions (detection rate of 78.4%) and lymph node metastases in 2/5 patients. The SUV_mean was 2.12+/−0.94 (range 0.70–4.38; tumor/blood 1.36+/−0.53; tumor/muscle 2.82+/−1.31) in bone-lesions and 2.21+/−1.18 (range 0.75–3.56) in lymph node metastases. Good visualization and detection of bone metastases was feasible due to a low background activity of the surrounding normal bone tissue.

Methods

12 patients with known metastasized prostate cancer according to conventional staging (including bone-scintigraphy and contrast-enhanced CT; median PSA 68.63 ng/ml, range 3.72-1935) were examined with PET after i.v.-injection of [¹⁸F]Galacto-RGD. Two blinded nuclear-medicine physicians evaluated the PET-scans in consensus concerning lesion detectability. Volumes-of-interest were drawn in the PET-scans over all metastases defined by conventional staging (maximum of 11 lesions/patient), over the left ventricle, liver and muscle and standardized-uptake-values (SUVs) were calculated.

Conclusions

Our data show generally elevated uptake of [¹⁸F]Galacto-RGD in bone metastases from prostate cancer with a marked inter- and intrapatient variability. While [¹⁸F]Galacto-RGD PET is inferior to bone scintigraphy for detection of osseous metastases, it might be valuable in patient screening and monitoring of αvβ3-targeted therapies due to the high variability of αvβ3-expression.

Integrins: Integrating the Biology and Therapy of Cell-cell Interactions

PURPOSE

Although the role of integrins has been described in a variety of diseases, these roles seem to be distinct. To date, no study has attempted to provide links to the various pathways by which such integrins can be involved in these diverse disease settings. The purpose of this review was to address this gap in our knowledge with the hypothesis that there is, in fact, a common pathway by which integrins may function.

METHODS

This article provides an in-depth perspective on the discovery, development, and design of therapeutics that modulate cellular function by targeting integrin:ligand interactions by reviewing the literature on this subject; the review included the most recent results of clinical and subclinical studies. A MEDLINE search was conducted for articles pertaining to the various issues related to integrins, and the most relevant articles are discussed (ie, not only those published in journals with a higher impact factor).

FINDINGS

It seems that the ligation of the integrins with their cognate ligands plays a major role in translating membrane dialogue into biological function. In addition, they also seem to play a major regulatory role that can enhance or inhibit biological function depending on the context within which such receptor:ligand interactions occur and the organ and tissues at which interactions occurs and is manipulated. Those studies that used statistical analyses have been included where appropriate.

IMPLICATIONS

Our findings show that anti-integrin treatment has the potential to become a valid coadjuvant in the treatment of several diseases including cancer, inflammatory diseases, HIv infection and cardiovascular diseases.

Angiogenesis regulation by nanocarriers bearing RNA interference

Since the approval of bevacizumab as anti-angiogenic therapy in 2004 by the FDA, an array of angiogenesis inhibitors have been developed and approved. However, results were disappointing with regard to their therapeutic efficacy. RNA interference approaches offer the possibility of rational design with high specificity, lacking in many current drug treatments for various diseases including cancer. However, in vivo delivery issues still represent a significant obstacle for widespread clinical applications. In the current review, we summarize the advances in the last decade in the field of angiogenesis-targeted RNA interference approaches, with special emphasis on oncology applications. We present pro-angiogenic and anti-angiogenic factors as potential targets, experimental evidence and clinical trials data on angiogenesis regulation by RNA interference. Consequent challenges and opportunities are discussed.

Multimodality Imaging in Tumor Angiogenesis: Present Status and Perspectives

Angiogenesis is a complex biological process that plays a central role in progression of tumor growth and metastasis. It led to a search for antiangiogenic molecules, and to design antiangiogenic strategies for cancer treatment. Noninvasive molecular imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), could be useful for lesion detection, to select patients likely to respond to antiangiogenic therapies, to confirm successful targeting, and dose optimization. Additionally, nuclear imaging techniques could also aid in the development of new angiogenesis-targeted drugs and their validation. Angiogenesis imaging can be categorized as targeted at three major cell types: (I) non-endothelial cell targets, (II) endothelial cell targets, and (III) extracellular matrix proteins and matrix proteases. Even if radiopharmaceuticals studying the metabolism and hypoxia can be also used for the study of angiogenesis, many of the agents used in nuclear imaging for this purpose are yet to be investigated. The purpose of this review is to describe the role of molecular imaging in tumor angiogenesis, highlighting the advances in this field.

Cell targeting peptides as smart ligands for targeting of therapeutic or diagnostic agents: a systematic review

Cell targeting peptides (CTP) are small peptides which have high affinity and specificity to a cell or tissue targets. They are typically identified by using phage display and chemical synthetic peptide library methods. CTPs have attracted considerable attention as a new class of ligands to delivery specifically therapeutic and diagnostic agents, because of the fact they have several advantages including easy synthesis, smaller physical sizes, lower immunogenicity and cytotoxicity and their simple and better conjugation to nano-carriers and therapeutic or diagnostic agents compared to conventional antibodies. In this systematic review, we will focus on the basic concepts concerning the use of cell-targeting peptides (CTPs), following the approaches of selecting them from peptide libraries. We discuss several developed strategies for cell-specific delivery of different cargos by CTPs, which are designed for drug delivery and diagnostic applications.

Endothelial cells: From innocent bystanders to active participants in immune responses

The endothelium is crucially important for the delivery of oxygen and nutrients throughout the body under homeostatic conditions. However, it also contributes to pathology, including the initiation and perpetuation of inflammation. Understanding the function of endothelial cells (ECs) in inflammatory diseases and molecular mechanisms involved may lead to novel approaches to dampen inflammation and restore homeostasis. In this article, we discuss the various functions of ECs in inflammation with a focus on pathological angiogenesis, attraction of immune cells, antigen presentation, immunoregulatory properties and endothelial-to-mesenchymal transition (EndMT). We also review the current literature on approaches to target these processes in ECs to modulate immune responses and advance anti-inflammatory therapies.

Evaluation of 99mTc-3PRGD2 integrin receptor imaging in hepatocellular carcinoma tumour-bearing mice: comparison with 18F-FDG metabolic imaging

Objective

Our study was designed to explore the utility of ^99mTc-HYNIC-PEG₄-E[PEG₄-c(RGDfK)]₂ (^99mTc-3PRGD₂) for the detection of hepatocellular carcinoma (HCC) and specifically to compare the diagnostic performance of ^99mTc-3PRGD₂ integrin receptor imaging and 2-18-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) metabolic imaging in a nude mouse model.

Methods

^99mTc-3PRGD₂ was synthesized using a HYNIC-3PRGD₂ lyophilized kit with ^99mTcO₄ labelling. The nude mouse animal model was established by subcutaneously injecting 5 × 10⁷/ml HepG2 cells into the shoulder flank of each mouse. Biodistribution studies were performed at 0.5, 1, 2 and 4 h after intravenous administration of 0.37 MBq of ^99mTc-3PRGD₂. Immunohistochemistry was performed to evaluate the expression level of integrin αvβ3 in the HCC tissues. Dynamic imaging was performed using list-mode after the administration of 55.5 MBq of ^99mTc-3PRGD₂, to reconstruct the multiphase images and acquire the best initial scan time. At 8, 12, 16, 20 and 24 days after inoculation with HepG2 cells, 55.5 MBq of ^99mTc-3PRGD₂ and 37 MBq of ¹⁸F-FDG were injected successively into the nude mouse model, subsequently, simultaneous SPECT/PET imaging was performed to calculate the tumour volume and tumour uptake of ^99mTc-3PRGD₂ and ¹⁸F-FDG.

Results

The biodistribution study first validated that the tumour uptake of ^99mTc-3PRGD₂ at the different time points was higher than that of all the other organs tested in the experiment, except for the kidney. Integrin αvβ3 expressed highly in early stage HCC and declined for further necrosis of the tumour tissue. Subcutaneous tumours were visualized clearly with excellent contrast under ^99mTc-3PRGD₂ SPECT/CT imaging, and the multiphase imaging comparison showed the tumours were prominent at 0.5 h, suggesting that the best initial scan time is 0.5 h post-injection. The comparison of the imaging results of the two methods showed that ^99mTc-3PRGD₂ integrin receptor imaging was more sensitive than ¹⁸F-FDG metabolic imaging for the detection of early stage HCC, meanwhile the tumour uptake of ^99mTc-3PRGD₂ was consistently higher than that of ¹⁸F-FDG. However, as tumour necrosis further increased in HCC tissues, the uptake of ¹⁸F-FDG was higher than that of ^99mTc-3PRGD₂.

Conclusion

Our study demonstrated that ^99mTc-3PRGD₂ is a valuable tumour molecular probe for the detection of early stage HCC compared with ¹⁸F-FDG, meriting further investigation of ^99mTc-3PRGD₂ as a novel SPECT tracer for tumour imaging.

Erianin inhibits indoleamine 2, 3-dioxygenase -induced tumor angiogenesis

Tumor angiogenesis is the key process in tumor growth and metastasis, and transfers essential nutrients for solid tumor. Inhibition of tumor angiogenesis has been recognized as a more effective anti-cancer strategy for NSCLC and has acquired certain therapeutic effects. IDO has non-immune functions including regulating tumor angiogenesis and IDO dysregulation in cancer pathogenesis has been valued. Erianin is a natural product isolated from Dendrobium chrysotoxum Lindl. The antitumor activity of erianin in many kinds of cancers had been demonstrated in previous studies. In this study, we demonstrated that IDO could promote the attachment of 2LL cells, the ability of migration, invasion and VM formation, as well as the tubules forming ability of HUVECs. We also find that erianin suppressed expression and enzyme ability of IDO and erianin could inhibit IDO-induced metastasis and invasion ability of 2LL cells significantly. Erianin not only blocked IDO-induced tube formation of HUVECs, but also suppressed VM formation of 2LL-IDO cells. What's more, we examined that Erianin might play its role in angiogenesis through down-regulating phosphorylation of JAK2/STAT3, inhibiting its downstream target genes MMP-2/-9 and some inflammatory mediators (COX-2, HIF-1α and IL-6), which were all induced by IDO. All these results indicated that erianin had anti-angiogenesis ability and could inhibit the expresison of IDO to prevent and treat the malignant tumors.

Carboplatin-Complexed and cRGD-Conjugated Unimolecular Nanoparticles for Targeted Ovarian Cancer Therapy

Platinum-based chemotherapy has been widely used to treat cancers including ovarian cancer; however, it suffers from dose-limiting toxicity. Judiciously designed drug nanocarriers can enhance the anticancer efficacy of platinum-based chemotherapy while reducing its systemic toxicity. Herein the authors report a stable and water-soluble unimolecular nanoparticle constructed from a hydrophilic multi-arm star block copolymer poly(amidoamine)-b-poly(aspartic acid)-b-poly(ethylene glycol) (PAMAM-PAsp-PEG) conjugated with both cRGD (cyclo(Arg-Gly-Asp-D-Phe-Cys) peptide and cyanine5 (Cy5) fluorescent dye as a platinum-based drug nanocarrier for targeted ovarian cancer therapy. Carboplatin is complexed to the poly(aspartic acid) inner shell via pH-responsive ion-dipole interactions between carboplatin and the carboxylate groups of poly(aspartic acid). Based on flow cytometry and confocal laser scanning microscopy analyses, cRGD-conjugated unimolecular nanoparticles exhibit much higher cellular uptake by ovarian cancer cells overexpressing α_v β₃ integrin than nontargeted (i.e., cRGD-lacking) ones. Carboplatin-complexed cRGD-conjugated nanoparticles also exhibit higher cytotoxicity than nontargeted nanoparticles as well as free carboplatin, while empty unimolecular nanoparticles show no cytotoxicity. These results indicate that stable unimolecular nanoparticles made of individual hydrophilic multi-arm star block copolymer molecules conjugate with tumor-targeting ligands and dyes (i.e., PAMAM-PAsp-PEG-cRGD/Cy5) are promising nanocarriers for platinum-based anticancer drugs for targeted cancer therapy.

Fabrication of RGD-conjugated Gd(OH)3:Eu nanorods with enhancement of magnetic resonance, luminescence imaging and in vivo tumor targeting

The development of multimodal probes with magnetic resonance imaging (MRI) and intraoperative fluorescence imaging is the most challenging task in the field of tumor diagnosis. Herein, a simple one-pot hydrothermal method is used to prepare Eu-doped Gd(OH)₃ nanorods (Gd(OH)₃:Eu NRs) with good fluorescence and the longitudinal relaxivity r₁ value of 4.78 (Gd mM s^-1). After dual-functionalized maleimide-polyethylene glycol-succinimide (Mal-PEG-NHS) macromolecules are coated on the surface of Gd(OH)₃:Eu NRs (PEG-NRs), the results of a lower degradation ratio in newborn calf serum (NCS), reactive oxygen species (ROS) generation in L929 cells and the hemolytic rate of PEG-NRs show their good cyto-compatibility and longer blood circulation time. Moreover, the actively tumor-targeting properties are endowed to NRs through the conjugation of cyclic arginine-glycine-aspartic acid (cRGD) (denoted RGD-NRs). The bio-distributions of RGD-NRs in tumor-bearing nude mice via tail-vein injection indicate that RGD-NRs are specifically taken-up by gliomas. The tests of in vivo T₁-weighted MR imaging via tail-vein injection confirm that RGD-NRs possess a higher positive signal-enhancement ability in gliomas. Besides, the better luminescence imaging of living cells under a fluorescence microscope and the clear in vivo fluorescence imaging further confirm the targeting properties and better in vivo optical imaging behavior of RGD-NRs.

In vitro and in vivo activities of an antitumor peptide HM-3: A special dose-efficacy relationship on an HCT‑116 xenograft model in nude mice

Anti-angiogenesis is an important therapy for cancer treatment. Peptide HM-3 is an integrin antagonist with anti-angiogenic and antitumor activity. Previous research found that HM-3 at an effective dose inhibited tumor growth whereas at higher doses, the inhibitory effect gradually decreased. In the present study, three human tumor cell lines, human colorectal cancer cell (HCT-116) and human hepatic cancer cell (Hep G-2 and SMMC-7721), were selected and their interactions with HM-3 were compared with western blot and flow cytometric assays. The effect of HM-3 on the migration of two tumor cell lines (HCT-116 and Hep G-2) was also evaluated and a bell-shaped dose-efficacy curve was found for both cell lines. Furthermore, in vivo imaging in BALB/c nude mice confirmed that HM-3 had a short half-life and targeted the tumor tissue. Moreover, on an HCT-116 xenograft model in BALB/c nude mice, HM-3 at 3 mg/kg inhibited tumor growth with an inhibition rate of 71.5% (by tumor mass) whereas at 12 and 48 mg/kg, the inhibition rates were 59.2 and 36.0%, respectively. Immunohistochemistry analyses found that both sunitinib (60 mg/kg) and HM-3 (3 and 48 mg/kg) decreased microvascular density and increased percent of HIF-1α and VEGF expressing cells. The present study investigated the effect of tumor microenvironments on the antitumor effect of HM-3 and concluded that HM-3 inhibited angiogenesis and thereafter tumor growth by directly inhibiting HUVEC migration. The special dose-efficacy curves for antitumor effect and for cell migration inhibition were correlated. The present study also confirmed that the effective dose has to be strictly defined for better clinical applications of anti‑angiogenic drugs such as HM-3.

WISP1-αvβ3 integrin signaling positively regulates TLR-triggered inflammation response in sepsis induced lung injury

We recently noted that the matricellular protein WISP1 contributes to sepsis induced acute lung injury (ALI) via integrin β6. In the current study, we pursued further aspects of WISP1 modulation of TLR signaling in lungs of mice after sepsis and TLR4 mediated release of TNF-α in macrophages. After confirming that TLR4 and CD14 are critical in transducing sepsis mediated ALI, we now demonstrate that intrapulmonary αvβ3 is increased by polymicrobrial sepsis in a TLR4, CD14 dependent fashion. Comparison of cultured macrophages revealed that WISP1 increased release of TNF-α from RAW264.7 cells with baseline expression of αvβ3, but primary cultures of peritoneal macrophages (PMø) required activation of TLR4 to induce de novo synthesis of αvβ3 enabling WISP1 to stimulate release of TNF-α. The specific requirement for β3 integrin was apparent when the effect of WISP1 was lost in PMø isolated from β3(-/-) mice. WISP1 enhanced TLR4 mediated ERK signaling and U0126 (an ERK inhibitor) blocked LPS induced β3 integrin expression and WISP1 enhanced TNF-α release. Collectively these data suggest that WISP1-αvβ3 integrin signaling is involved in TLR4 pathways in macrophages and may be an important contributor to TLR4/CD14 mediated inflammation in sepsis induced lung injury.

Transarterial administration of integrin inhibitor loaded nanoparticles combined with transarterial chemoembolization for treating hepatocellular carcinoma in a rat model

AIM: To compare the effect of transarterial chemoembolization (TACE) plus GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro, integrin-inhibitor) loaded nanoparticles with TACE alone or TACE + GRGDSP in a rat model of liver tumor.

METHODS: Morris hepatoma 3924A tumors were implanted in the livers of 30 ACI rats. The ACI rats were divided randomly into three groups (10 animals each). Tumor volume before treatment (V1) was examined by magnetic resonance imaging (MRI), and then, after laparotomy and placement of a PE-10 catheter into the hepatic artery, the following interventional protocols were performed: TACE (mitomycin C + lipiodol + degradable starch microspheres) + GRGDSP loaded nanoparticles for group A; TACE + GRGDSP for group B (control group 1); TACE alone for group C (control group 2). Tumor volume (V2) was assessed by MRI and the mean ratio of the post-treatment to pretreatment tumor volumes (V2/V1) was calculated. Immunohistochemical analysis was performed to assess the quantification of matrix metalloprotein 9 (MMP-9) and vascular endothelial growth factor (VEGF) positive tumor cells in each treatment group.

RESULTS: The mean tumor growth ratios (V2/V1) were 1.3649 ± 0.1194 in group A, 2.0770 ± 0.1595 in group B, and 3.2148 ± 0.1075 in group C. Compared with groups B and C, group A showed a significant reduction in tumor volume. Lower expression of MMP-9 and VEGF in hepatocellular carcinoma was observed in group A than in groups B and C. The angiogenesis of tumor was evaluated using anti-VEGF antibodies, and the metastasis of tumor was assessed using anti-MMP-9 antibody. MMP-9 and VEGF were expressed in all specimens. The immunoexpression of these proteins was confirmed by the presence of red cytoplasmic staining in tumor cells. Lower expression of MMP-9 and VEGF in hepatocellular carcinoma was observed in group A than in groups B and C.

CONCLUSION: Transarterial administration of integrin inhibitor loaded nanoparticles combined with TACE evidently retards tumor growth and intrahepatic metastases compared with TACE alone or TACE plus integrin inhibitor in an animal model of hepatocellular carcinoma.

Design, preparation and characterization of cyclic RGDfK peptide modified poly(ethylene glycol)-block-poly(lactic acid) micelle for targeted delivery

Molecular targeted cancer therapy is a promising strategy to overcome the lack of specificity of anticancer drug. While the binding of c(RGDfK) (cyclic Arginine-Glycine-Aspartic acid-Phenylalanine-Lysine) to αvβ3 over-expressed on tumor cell has been validated, the underlying interaction remains poorly understood. In this work, docking calculation was applied to investigate the interactions between c(RGDfK)/c(RGDfK)-PEG and αvβ3. The calculated results indicated that c(RGDfK) interacted with αvβ3 mainly by electrostatic interaction, stabilization interaction, and hydrophobic interaction. Conjugation of PEG chain to the c(RGDfK) weakened the binding affinity of c(RGDfK) to αvβ3. Accordingly, docetaxel(DTX)-loaded target micelles (c(RGDfK)-PEG-PLA/PEG-PLA/DTX) were designed, characterized and evaluated using HeLa cells. In vitro release studies demonstrated both target and non-target micelles displayed almost the same profiles, which best fit in Ritger-Peppas model. Cellular uptake and MTT studies revealed that the target micelles with the presence of c(RGDfK) were more efficiently taken up by HeLa cells and significantly improved the cytotoxicity compared to that of non-target micelles. Cell inhibition rate of target micelles was improved by 20% after 24h. Our findings suggest that target micelles may be a potential anticancer drug delivery system in the treatment of integrin αvβ3 over-expressed on tumor cell.

γ-AApeptides: Design, Structure, and Applications

The development of sequence-specific peptidomimetics has led to a variety of fascinating discoveries in chemical biology. Many peptidomimetics can mimic primary, secondary, and even tertiary structure of peptides and proteins, and because of their unnatural backbones, they also possess significantly enhanced resistance to enzymatic hydrolysis, improved bioavailability, and chemodiversity. It is known that peptide nucleic acids (PNAs) are peptidic sequences developed for the mimicry of nucleic acids; however, their unique backbone as the molecular scaffold of peptidomimetics to mimic structure and function of bioactive peptides has not been investigated systematically. As such, we recently developed a new class of peptidomimetics, "γ-AApeptides", based on the chiral γ-PNA backbone. They are termed γ-AApeptides because they are the oligomers of γ-substituted-N-acylated-N-aminoethyl amino acids. Similar to other classes of peptidomimetics, γ-AApeptides are also resistant to proteolytic degradation and possess the potential to enhance chemodiversity. Moreover, in our scientific journey on the exploration of this class of peptidomimetics, we have discovered some intriguing structures and functions of γ-AApeptides. In this Account, we summarize the current development and application of γ-AApeptides with biological potential. Briefly, both linear and cyclic (either through head-to-tail or head-to-side-chain cyclization) γ-AApeptides with diverse functional groups can be synthesized easily on the solid phase using the synthetic protocol we developed. γ-AApeptides could mimic the primary structure of peptides, as they project the same number of side chains as peptides of the same lengths. For instance, they could mimic the Tat peptide to permeate cell membranes and bind to HIV RNA with high specificity and affinity. Certain γ-AApeptides show similar activity to the RGD peptide and target integrin specifically on the cell surface. γ-AApeptides with function akin to fMLF peptides are also identified. More importantly, we found that γ-AApeptides can fold into discrete secondary structures, such as helical and β-turn-like structures. Therefore, they could be rationally designed for a range of biological applications. For instance, γ-AApeptides can mimic host-defense peptides and display potent and broad-spectrum activity toward a panel of drug-resistant bacterial pathogens. Meanwhile, because of their stability against proteolysis and their chemodiversity, γ-AApeptides are also amenable for combinatorial screening. We demonstrate that, through combinatorial selection, certain γ-AApeptides are identified to inhibit Aβ40 peptide aggregation, suggesting their potential use as a molecular probe to intervene in Alzheimer's disease. In addition, a few γ-AApeptides identified from the γ-AApeptide library have been shown to bind to the DNA-binding domain of STAT3 and antagonize STAT3/DNA interactions. Our studies suggest that, with further studies and exploration on both structures and functions, γ-AApeptides may emerge to be a new class of peptidomimetics that play an important role in chemical biology and biomedical sciences.

In Vivo Biodistribution and Anti-Tumor Efficacy Evaluation of Doxorubicin and Paclitaxel-Loaded Pluronic Micelles Decorated with c(RGDyK) Peptide

The treatment of squamous carcinoma, especially multidrug resistance (MDR) tumors, represents one of the most formidable challenges in oncology. In this study, integrin-mediated Pluronic-based micellar system (c(RGDyK)-FP-DP) was proposed as a drug delivery system to enhance the in vivo anti-tumor efficacy in MDR human squamous carcinoma (KBv)-bearing. Following the recognition by integrin proteins express on the cell surface, cellular uptake and in vitro anti-tumor efficacy of c(RGDyK)-FP-DP were better than conventional PF-DP in KBv cells. The tumor homing specificity and further in vivo anticancer efficacy of c(RGDyK)-FP-DP were performed using subcutaneous KBv tumor-bearing mice model, respectively. Compared with PF-DP, c(RGDyK)-FP-DP demonstrated more drug accumulation in tumor and relatively less drug accumulation in heart, and an extended median survival time in the KBv tumor-bearing mice model. Furthermore, preliminary in vivo subacute toxicity evaluation was also conducted by the measurement of histopathology, blood cell counts and clinical biochemistry parameters. Results showed that no obvious toxicity was observed to the hematological system or heart after a series of intravenous administration of c(RGDyK)-FP-DP. In conclusion, our results suggested that c(RGDyK) peptide conjugated Pluronic micelles could be a promising vehicle for enhancing the treatment of MDR human squamous carcinoma.

RGD and polyhistidine tumor homing peptides potentiates the action of human Maspin as an antineoplastic candidate

Maspin, a non-inhibitory member of serine protease family, acts as an effective tumor suppressor by inhibiting cell inhesion and mobility. We found that exogenous wild-type rMaspin had a low effect on tumor growth in vivo. However, when the peptide Arg-Gly-Asp-hexahistidine (RGD-6His) was introduced into rMaspin, the modified rMaspin showed significant inhibitory activity in angiogenic assays and tumor-bearing animal models. Overall, our data suggested that both the RGD and hexahistidine fragments contributed to improve the fusion protein activity and polyhistidine peptide could be considered as flexible linker to separate RGD and Maspin moieties to avoid function interference. Besides, it is an efficient tag to achieve purified recombinant proteins. Furthermore, rMaspin fusing with RGD and hexahistidine could be a viable anticancer candidate.

The Effect of Stromal Integrin β3-Deficiency on Two Different Tumors in Mice

There is an increasing focus on the tumor microenvironment in carcinogenesis. Integrins are important receptors and adhesion molecules in this environment and have been shown to be involved in cell adhesion, proliferation, differentiation and migration. The present study aimed to evaluate the effect of stromal integrin β3-deficiency on tumor growth, angiogenesis, interstitial fluid pressure (PIF), fibrosis and metastasis in a murine breast cancer (4T1) and a prostate tumor (RM11) model. We showed that stromal integrin β3-deficiency led to an elevation in PIF that correlated to a shift towards thicker collagen fibrils in the 4T1 mammary tumor. In the RM11 prostate carcinoma model there was no effect of integrin β3-deficiency on PIF and collagen fibril thickness. These findings support the notion that changes in the collagen scaffold influence PIF, and also indicate that there must be important crosstalk between the stroma and tumor cells, in a tumor cell line specific manner. Furthermore, stromal integrin β3-deficiency had no effect on tumor growth or angiogenesis in both tumor models and no effect on lung metastasis in the 4T1 mammary tumor model. In conclusion, the stromal β3 integrin influence PIF, possibly via its effect on the structure of the collagen network, in a tumor cell line dependent manner.

In Vitro Assays for Endothelial Cell Functions Required for Angiogenesis: Proliferation, Motility, Tubular Differentiation, and Matrix Proteolysis

This chapter deconstructs the process of angiogenesis into its component parts in order to provide simple assays to measure discrete endothelial cell functions. The techniques described will be suitable for studying stimulators and/or inhibitors of angiogenesis and determining which aspect of the process is modulated. The assays are designed to be robust and straightforward, using human umbilical vein endothelial cells, but with an option to use other sources such as microvascular endothelial cells from various tissues or lymphatic endothelial cells. It must be appreciated that such reductionist approaches cannot cover the complexity of the angiogenic process as a whole, incorporating as it does a myriad of positive and negative signals, three-dimensional interactions with host tissues and many accessory cells including fibroblasts, macrophages, pericytes and platelets. The extent to which in vitro assays predict physiological or pathological processes in vivo (e.g., wound healing, tumor angiogenesis) or surrogate techniques such as the use of Matrigel™ plugs, sponge implants, corneal assays etc remains to be determined.