Fighting cancer by attacking its blood supply

miR-181a Targets RGS16 to Promote Chondrosarcoma Growth, Angiogenesis, and Metastasis

Chondrosarcoma is the most common primary malignant bone tumor in adults, has no effective systemic treatment, and patients with this disease have poor survival. Altered expression of microRNA (miR) is involved in tumorigenesis; however, its role in chondrosarcoma is undetermined. miR-181a is overexpressed in high-grade chondrosarcoma, is upregulated by hypoxia, and increases VEGF expression. Here, the purpose was to determine the mechanism of miR-181a regulation of VEGF, determine whether miR-181a overexpression promotes tumor progression, and to evaluate an antagomir-based approach for chondrosarcoma treatment. Therapeutic inhibition of miR-181a decreased expression of VEGF and MMP1 in vitro, and angiogenesis, MMP1 activity, tumor growth, and lung metastasis, all by more than 50%, in a xenograft mouse model. A target of miR-181a is a regulator of G-protein signaling 16 (RGS16), a negative regulator of CXC chemokine receptor 4 (CXCR4) signaling. CXCR4 signaling is increased in chondrosarcoma, its expression is also increased by hypoxia, and is associated with angiogenesis and metastasis; however, receptor blockade is only partially effective. RGS16 expression is restored after miR-181a inhibition and partially accounts for the antiangiogenic and antimetastatic effects of miR-181a inhibition. These data establish miR-181a as an oncomiR that promotes chondrosarcoma progression through a new mechanism involving enhancement of CXCR4 signaling by inhibition of RGS16.

IMPLICATIONS

Targeting miR-181a can inhibit tumor angiogenesis, growth, and metastasis, thus suggesting the possibility of antagomir-based therapy in chondrosarcoma.

Advanced targeted nanomedicine

Targeted drug delivery has been the major topic in drug formulation and delivery. As nanomedicine emerges to create nano scale therapeutics and diagnostics, it is still essential to embed targeting capability to these novel systems to make them useful. Here we discuss various targeting approaches for delivery of therapeutic and diagnostic nano materials in view of search for more universal methods to target diseased tissues. Many diseases are accompanied with hypoxia and acidosis. Coating nanoparticles with pH Low Insertion Peptides (pHLIPs) increases efficiency of targeting acidic diseased tissues. It has been showing promising results to create future nanotheranostics for cancer and other diseases which are dominating in the present world.

Antivascular ultrasound therapy: magnetic resonance imaging validation and activation of the immune response in murine melanoma

OBJECTIVES

The purpose of this study was to investigate the treatment effects of antivascular ultrasound (US) with dynamic contrast-enhanced magnetic resonance imaging (MRI), contrast-enhanced sonography, and histopathologic analysis in a murine melanoma model.

METHODS

Subcutaneous K1735 murine melanoma tumors were grown in syngeneic C3H/HeN mice. Quantitative tumor perfusion characteristics were measured before antivascular US treatment with both dynamic contrast-enhanced MRI and high-resolution contrast-enhanced sonography. Tumors were subsequently treated with 1 or 3 minutes of continuous low-intensity US after intravenous administration of a US contrast agent. Treatment effects were assessed by quantitative dynamic contrast-enhanced MRI, contrast-enhanced sonography, histopathologic analysis, and immunohistochemistry.

RESULTS

Low-intensity antivascular US treatment resulted in approximately a doubling and tripling of the time to peak enhancement on dynamic contrast-enhanced MRI in the 1- and 3-minute treatment groups, respectively, along with a significant decrease in contrast wash-out (P < .01). There was a potent reduction in tumor perfusion on contrast-enhanced sonography, with approximately 40% and 70% reductions in the tumor area perfused as assessed by contrast-enhanced sonography after 1 (P < .05) and 3 (P < .01) minutes of antivascular US. The pathologic and histologic changes spatially correlated with the regions of diminished perfusion seen on contrast-enhanced sonography and dynamic contrast-enhanced MRI. Antivascular US therapy resulted in a significant increase in the number of hypoxia-inducible factor 1A(+) cells, indicating tumor hypoxia (P < .01), and of CD45(+)/CD3(+) cells in tumors after treatment, in keeping with increased T-cell infiltration (P < .01).

CONCLUSIONS

Antivascular US treatment effects extend beyond direct cytotoxicity from hemorrhagic necrosis to include ischemia-mediated cytotoxicity, enhanced small molecule retention, and intratumoral immune activation.

Immunopreventive effects against murine H22 hepatocellular carcinoma in vivo by a DNA vaccine targeting a gastrin- releasing peptide

There is a continuing need for innovative alternative therapies for liver cancer. DNA vaccines for hormone/ growth factor immune deprivation represent a feasible and attractive approach for cancer treatment. We reported a preventive effect of a DNA vaccine based on six copies of the B cell epitope GRP18-27 with optimized adjuvants against H22 hepatocarcinoma. Vaccination with pCR3.1-VS-HSP65-TP-GRP6-M2 (vaccine) elicited much higher level of anti-GRP antibodies and proved efficacious in preventing growth of transplanted hepatocarcinoma cells. The tumor size and weight were significantly lower (p<0.05) in the vaccine subgroup than in the control pCR3.1-VS-TP-HSP65-TP-GRP6, pCR3.1-VS-TP-HSP65-TP-M2 or saline subgroups. In addition, significant reduction of tumor-induced angiogenesis associated with intradermal tumors of H22 cells was observed. These potent effects may open ways towards the development of new immunotherapeutic approaches in the treatment of liver cancer.

Increased angiogenesis and FGFR protein expression indicate a favourable prognosis in bladder cancer

Compared to other members of the fibroblast growth factor receptor (FGFR) family, only few studies investigate FGFR3 in tumour angiogenesis. We investigated the connection between angiogenesis and FGF/FGFR expression including FGFR3 mutation status in urothelial carcinomas. Immunohistochemistry was performed in invasive and non-invasive urothelial cancers of 61 patients. Protein expression of CD31, factor VIII (FVIII), FGF-1/2, FGFR1, FGFR3 and FGFR4 and FGFR3 mutation status were evaluated. Morphometric assessment of angiogenesis including microvessel count (MVC) and vascular surface area (VSA) was analysed. Correlation and survival analyses (overall survival (OS) and disease-free survival (DFS)) with univariate and multivariate analyses were performed. CD31 values (MVC and VSA) significantly correlated with OS and DFS. OS and DFS were significantly better in patients with FGFR3 overexpression. Multivariate analysis revealed FGFR3 protein expression and tumour grading (WHO classification 2004) as independent prognostic factors of OS and VSA of CD31 and FGFR3 protein expression of DFS. FGFR3 mutation status was correlated with VSA measured by FVIII. FGFR3 may be able to induce a pro-angiogenic phenotype in urothelial carcinomas and significantly influence prognosis. Consequently, FGFR3 is a potential therapeutic target also from the angiogenesis perspective.

Orphan nuclear receptor TR3/Nur77 improves wound healing by upregulating the expression of integrin β4

Tissue repair/wound healing, in which angiogenesis plays an important role, is a critical step in many diseases including chronic wound, myocardial infarction, stroke, cancer, and inflammation. Recently, we were the first to report that orphan nuclear receptor TR3/Nur77 is a critical mediator of angiogenesis and its associated microvessel permeability. Tumor growth and angiogenesis induced by VEGF-A, histamine, and serotonin are almost completely inhibited in Nur77 knockout mice. However, it is not known whether TR3/Nur77 plays any roles in wound healing. In these studies, skin wound-healing assay was performed in 3 types of genetically modified mice having various Nur77 activities. We found that ectopic induction of Nur77 in endothelial cells of mice is sufficient to improve skin wound healing. Although skin wound healing in Nur77 knockout mice is comparable to the wild-type control mice, the process is significantly delayed in the EC-Nur77-DN mice, in which a dominant negative Nur77 mutant is inducibly and specifically expressed in mouse endothelial cells. By a loss-of-function assay, we elucidate a novel feed-forward signaling pathway, integrin β4 → PI3K → Akt → FAK, by which TR3 mediates HUVEC migration. Furthermore, TR3/Nur77 regulates the expression of integrin β4 by targeting its promoter activity. In conclusion, expression of TR3/Nur77 improves wound healing by targeting integrin β4. TR3/Nur77 is a potential candidate for proangiogenic therapy. The results further suggest that TR3/Nur77 is required for pathologic angiogenesis but not for developmental/physiologic angiogenesis and that Nur77 and its family members play a redundant role in normal skin wound healing.

The role of tight junctions in cancer metastasis

Over the last decade, it has become apparent that the tight junction (TJ) is a key component in tumour progression and metastasis. In addition to its role in the control of paracellular diffusion of ions and certain molecules, the TJ has a vital role in maintaining cell to cell adhesion and tissue integrity. Changes in the expression and/or distribution of TJ proteins can result in loss in cohesion of the TJ structure, which in turn results in the ability of cancer cells to become invasive and then ultimately lead to the metastasis of cancer cells. This review will discuss recent insights into how TJ are involved in the process of tumour metastasis.

Differential regulation of orphan nuclear receptor TR3 transcript variants by novel vascular growth factor signaling pathways

Angiogenesis is a hallmark of many diseases, including cancer, ischemic heart disease, inflammation, and others. It is well known that vascular endothelial growth factor (VEGF) is the most important angiogenic factor. Recently, we demonstrated that orphan nuclear receptor TR3 (mouse Nur77 and rat NGFI-B) plays critical roles in tumor growth and angiogenesis induced by VEGF-A in vitro and in vivo. However, the signaling pathways that mediate the expression of TR3 induced by VEGF are still not completely understood. Here we reported that 3 TR3 transcript variants (TR3-TVs) are expressed at differential levels, and regulated differentially in endothelial cells. While the expression of TR3-TV1 is relatively low, the expression of TR3-TV2 is up-regulated markedly, and the expression of TR3-TV3 is up-regulated moderately in endothelial cells induced by VEGF-A. The kinetics of the induction of these TR3-TVs is different. We also found that several signaling pathways, including calcium-PLC-PKC-PKD1 pathway, NF-κB pathway, and MAP kinase (ERK, p38, and JNK) pathways are important for VEGF-A-induced TR3-TV2 and TR3-TV3 mRNA induction. More important, we found that VEGF-A or VEGF-E, but not VEGF-B, nor placenta growth factor (PlGF), induces the phosphorylation of insulin-like growth factor-1 receptor (IGF-1R) and the interaction of VEGF receptor 2/kinase insert domain receptor (VEGFR2/KDR) with IGF-1R, which mediates the expression of TR3-TV2, but not TR3-TV3. Taking together, we demonstrate that TR3-TVs are differentially regulated by VEGF-A and identify a novel signaling pathway by which VEGF-A and VEGF-E, but neither VEGF-B, nor PlGF, induce the interaction of VEGFR2/KDR with IGF-1R, resulting in IGF-1R transactivation to induce the high level expression of TR3-TV2. Our data not only elucidate the signaling pathways by which TR3-TVs are regulated, but extend the molecular mechanism, by which VEGF-A-induced angiogenesis. These studies should permit the development of screening assays for compounds that inhibit VEGF signaling.

Factor-inhibiting hypoxia-inducible factor expression in patients with high-risk locally advanced renal cell carcinoma and its relationship with tumor progression

Hypoxia-inducible factor (HIF) plays an important role in renal cell carcinoma (RCC) associated with angiogenesis. Factor-inhibiting HIF (FIH), which is the upstream mediator protein of HIF, is receiving more attention today. In the present study, the role of FIH expression in high-risk locally advanced renal cell carcinoma (LARCC) was explored. Eighty-eight high-risk LARCC cases were divided into two groups based on their prognosis. Using immunohistochemical staining, the correlations of FIH expression along with clinicopathological factors, progression-free survival (PFS), and overall survival (OS) were analyzed. FIH was mainly located in the cytoplasm (34/88) and nucleus (31/88) of the renal tumor cell. Nuclear negative expression or cytoplasmic positive expression of FIH were associated with an increased risk of disease progression (p = 0.007 and p < 0.001, respectively) and worse OS (p = 0.020 and p = 0.008, respectively). Using the group with nuclear and cytoplasmic FIH negative expression as reference, further stratified analysis found that the exclusive nuclear FIH expression group had a better PFS and OS [hazard ratio (HR) = 0.153, p = 0.07 and HR = 0, p = 0.961, respectively], and the exclusive cytoplasmic FIH positive group experienced the worst PFS and OS (HR = 2.876, p = 0.005 and HR = 2.799, p = 0.034, respectively). In addition, nuclear negative expression of FIH was associated with a significant negative predictive value for the effect of interferon-alpha (IFN-α) on PFS (p = 0.045). The nuclear negative and cytoplasmic positive expressions of FIH were identified not only as risk factors for disease progression in high-risk LARCC postoperative patients, but also to be associated with poor OS. Furthermore, the nuclear negative expression of FIH may be a promising biomarker for postoperative adjuvant therapy.

Early detection of antiangiogenic treatment responses in a mouse xenograft tumor model using quantitative perfusion MRI

Angiogenesis plays a major role in tumor growth and metastasis, with tumor perfusion regarded as a marker for angiogenesis. To evaluate antiangiogenic treatment response in vivo, we investigated arterial spin labeling (ASL) magnetic resonance imaging (MRI) to measure tumor perfusion quantitatively. Chronic and 24-h acute treatment responses to bevacizumab were assessed by ASL and dynamic-contrast-enhanced (DCE) MRI in the A498 xenograft mouse model. After the MRI, tumor vasculature was assessed by CD34 staining. After 39 days of chronic treatment, tumor perfusion decreased to 44.8 ± 16.1 mL/100 g/min (P < 0.05), compared to 92.6 ± 42.9 mL/100 g/min in the control group. In the acute treatment study, tumor perfusion in the treated group decreased from 107.2 ± 32.7 to 73.7 ± 27.8 mL/100 g/min (P < 0.01; two-way analysis of variance), as well as compared with control group post dosing. A significant reduction in vessel density and vessel size was observed after the chronic treatment, while only vessel size was reduced 24 h after acute treatment. The tumor perfusion correlated with vessel size (r = 0.66; P < 0.005) after chronic, but not after acute treatment. The results from DCE-MRI also detected a significant change between treated and control groups in both chronic and acute treatment studies, but not between 0 and 24 h in the acute treatment group. These results indicate that tumor perfusion measured by MRI can detect early vascular responses to antiangiogenic treatment. With its noninvasive and quantitative nature, ASL MRI would be valuable for longitudinal assessment of tumor perfusion and in translation from animal models to human.

Theranostic tumor homing nanocarriers for the treatment of lung cancer

The drugs/strategies to selectively inhibit tumor blood supply have generated interest in recent years for enhancement of cancer therapeutics. The objective of this study was to formulate tumor homing PEGylated CREKA peptide conjugated theranostic nanoparticles of DIM-C-pPhC6H5 (DIM-P) and investigate in vivo antitumor activity as well as evaluate the targeted efficiency to lung tumors using imaging techniques. DIM-P loaded Nanoparticles (NCs-D) were prepared using lipids, and DOGS-NTA-Ni and the surface of NCs-D were modified with PEGylated CREKA peptide (PCNCs-D). PCNCs-D showed 3 fold higher binding to clotted plasma proteins in tumor vasculature compared to NCs-D. PCNCs-D showed 26%±4% and 22%±5% increase in tumor reduction compared to NCs-D in metastatic and orthotopic models respectively. In-vivo imaging studies showed ~40 folds higher migration of PCNCs-Di in tumor vasculature than NCs-Di. Our studies demonstrate the role of PCNCs-D as theranostic tumor homing drug delivery and imaging systems for lung cancer diagnosis and treatment.

FROM THE CLINICAL EDITOR

This study demonstrates a very efficient delivery system to address lung cancer growth through blood supply inhibition.

Methyl 4-(benz-yloxy)-3-meth-oxy-benzo-ate

In the title compound, C₁₆H₁₆O₄, the aromatic rings are almost normal to one another, making a dihedral angle of 85.81 (10)°. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming chains propagating along the b-axis direction. There are also C—H⋯π inter­actions present which link the chains, forming two-dimensional networks lying parallel to (102).

Fisetin inhibits matrix metalloproteinases and reduces tumor cell invasiveness and endothelial cell tube formation

Matrix metalloproteinases (MMPs) play an important role in tissue remodeling during normal physiological situations and pathological implications such as tumor invasion and metastasis. MMP inhibitors were screened from extracts of medicinal herbs by an enzymatic assay using the MMP-14 catalytic domain. Among samples tested, a methanol extract of the root of Dalbergia odorifera T. CHEN (Leguminosae) showed the strongest inhibitory activity. The inhibitory component was purified through fractionation methods and identified as fisetin, abundant in many fruits and vegetables. In addition to inhibition of MMP-14, fisetin inhibits MMP-1, MMP-3, MMP-7, and MMP-9, more efficiently than a naturally occurring MMP inhibitor tetracycline. Fisetin dose-dependently inhibits proliferation of fibrosarcoma HT-1080 cells and human umbilical vascular endothelial cells (HUVECs), MMP-14-mediated activation of proMMP-2 in HT-1080 cells, invasiveness of HT-1080 cells, and in vitro tube formation of HUVECs. Therefore, fisetin could be valuable as a chemopreventive agent against cancer and a lead compound for development of therapeutic MMP inhibitors.

Photodynamic therapy involves an antiangiogenic mechanism and is enhanced by ferrochelatase inhibitor in urothelial carcinoma

The purpose of the present study was to investigate the mechanism of photodynamic therapy (PDT) supplemented with exogenously added 5-aminolevulinic acid (ALA) on human urothelial cancer (UC). Moreover, we aimed to determine whether the therapeutic effects of ALA-based PDT (ALA-PDT) for UC could be enhanced by deferoxamine (DFX), an inhibitor of ferrochelatase. The efficiency of ALA-PDT on these cells was analyzed using flow cytometry and the type of cell death was also assessed. The ALA-PDT promoting effect of DFX was examined on both UC cells and human umbilical vein endothelial cells (HUVEC). The ALA-PDT decreased levels of mitochondrial membrane potential and induced cell death mainly via apoptosis in these cells. Moreover, inhibition of ferrochelatase by DFX led to an increase of protoporphyrin IX (PpIX) accumulation and enhanced the effect of ALA-PDT on UC cells. We further investigated the effect of DFX on in vivo PDT with a tumor-bearing animal model and found that DFX efficiently enhanced tumor cell apoptosis. ALA-PDT induced death of neovascular endothelial cells in tumors but did not affect small vessel endothelial cells in normal tissues surrounding the tumor. Furthermore, DFX enhanced inhibition of neovascularization. These results demonstrated ALA-PDT dominantly induced apoptosis over necrosis by direct action on UC as well as via antiangiogenic action on neovacular endothelial cells, suggesting that the therapeutic damage by ALA-PDT could be kept to a minimum in the surrounding normal tissues. In addition, increased accumulation of PpIX by DFX could enhance this effectiveness of ALA-PDT.

Angiogenesis is a link between atherosclerosis and tumorigenesis: role of LOX-1

Angiogenesis is defined as the formation of new blood vessels sprouting from pre-existing vessels. It plays an important role not only in physiological situations such as embryonic vascular development and wound healing, but also in pathological conditions including atherogenesis and evolution and spread of certain tumors. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a receptor for oxidized low density lipoprotein (ox-LDL), is mainly expressed in endothelial cells. It has diverse physiological functions and it could be a link between atherogenesis and tumorigenesis. The risk factors for atherosclerosis like hypertension, diabetes mellitus and hyperlipidemia are associated with LOX-1. Dyslipidemia and obesity are also being recognized as risk factor for certain tumors. LOX-1 is also found to be important for maintaining the transformed state in developmentally diverse cancer cell lines and for tumor growth. There is emerging evidence that LOX-1 plays an important role in the angiogenesis process. In this review, we outline the roles of angiogenesis in atherogenesis and tumorigenesis, and describe the role of LOX-1 as a potential molecular target for blocking angiogenesis.

The role of neurokinin-1 receptor in the microenvironment of inflammation and cancer

The recent years have witnessed an exponential increase in cancer research, leading to a considerable investment in the field. However, with few exceptions, this effort has not yet translated into a better overall prognosis for patients with cancer, and the search for new drug targets continues. After binding to the specific neurokinin-1 (NK-1) receptor, the peptide substance P (SP), which is widely distributed in both the central and peripheral nervous systems, triggers a wide variety of functions. Antagonists against the NK-1 receptor are safe clinical drugs that are known to have anti-inflammatory, analgesic, anxiolytic, antidepressant, and antiemetic effects. Recently, it has become apparent that SP can induce tumor cell proliferation, angiogenesis, and migration via the NK-1 receptor, and that the SP/NK-1 receptor complex is an integral part of the microenvironment of inflammation and cancer. Therefore, the use of NK-1 receptor antagonists as a novel and promising approach for treating patients with cancer is currently under intense investigation. In this paper, we evaluate the recent scientific developments regarding this receptor system, its role in the microenvironment of inflammation and cancer, and its potentials and pitfalls for the usage as part of modern anticancer strategies.

Xanthohumol inhibits growth and vascularization of developing endometriotic lesions

BACKGROUND

Xanthohumol is a prenylated flavonoid isolated from hops, which is known to act as a pleiotropic cancer chemopreventive agent owing to its anti-proliferative, anti-inflammatory and anti-angiogenic properties. In the present study, we analyzed, for the first time, whether this dietary compound may also be used for the treatment of endometriosis.

METHODS

Peritoneal and mesenteric endometriotic lesions were surgically induced in BALB/c mice by uterine tissue transplantation into the abdominal cavity. The animals were treated daily with 100 µM xanthohumol (n= 8) or vehicle (control, n= 8) via the drinking water, starting 3 days before tissue transplantations. Lesion growth, cyst formation and vascularization were subsequently analyzed by means of high-resolution ultrasound imaging (at Day 0 and then once per week for 28 days), caliper measurements, western blotting, histology and immunohistochemistry over 4 weeks.

RESULTS

In the treatment and control groups, uterine grafts developed typical endometriotic lesions with cyst-like dilated glands surrounded by a vascularized endometrial stroma. However, xanthohumol efficiently decreased the size of these lesions at Day 28, independent of their localization within the peritoneal cavity, compared with control (peritoneal: P =0.041; mesenteric: P =0.038). This was associated with a reduced level of phosphoinositide 3-kinase protein. Moreover, vascularization of xanthohumol-treated lesions was suppressed, as indicated by a significantly lower microvessel density at Day 28 when compared with vehicle-treated controls (peritoneal: P =0.026; mesenteric: P =0.004). Additional analyses revealed that treatment with xanthohumol did not affect the histomorphology, proliferation and vascularization of the uterine horns and ovaries.

CONCLUSIONS

Taken together, these experimental findings suggest that xanthohumol inhibits the development of endometriotic lesions in mice without inducing serious side effects in the reproductive organs. Thus, xanthohumol represents a promising dietary phytochemical that, after further testing, may be considered for the use in the selective treatment of endometriotic lesions.

Semaphorin 3A suppresses tumor growth and metastasis in mice melanoma model

BACKGROUND

Recent understanding on cancer therapy indicated that targeting metastatic signature or angiogenic switch could be a promising and rational approach to combat cancer. Advancement in cancer research has demonstrated the potential role of various tumor suppressor proteins in inhibition of cancer progression. Current studies have shown that axonal sprouting inhibitor, semaphorin 3A (Sema 3A) acts as a potent suppressor of tumor angiogenesis in various cancer models. However, the function of Sema 3A in regulation of melanoma progression is not well studied, and yet to be the subject of intense investigation.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, using multiple in vitro and in vivo approaches we have demonstrated that Sema 3A acts as a potent tumor suppressor in vitro and in vivo mice (C57BL/6) models. Mouse melanoma (B16F10) cells overexpressed with Sema 3A resulted in significant inhibition of cell motility, invasiveness and proliferation as well as suppression of in vivo tumor growth, angiogenesis and metastasis in mice models. Moreover, we have observed that Sema 3A overexpressed melanoma clone showed increased sensitivity towards curcumin and Dacarbazine, anti-cancer agents.

CONCLUSIONS

Our results demonstrate, at least in part, the functional approach underlying Sema 3A mediated inhibition of tumorigenesis and angiogenesis and a clear understanding of such a process may facilitate the development of novel therapeutic strategy for the treatment of cancer.

Mechanisms of resistance to vascular endothelial growth factor blockade

Angiogenesis is essential for the growth of primary tumors and for their metastasis. This process is induced by factors, such as vascular endothelial growth factors (VEGFs), that bind to transmembrane VEGF receptors (VEGFRs). VEGF-A is the primary factor involved with angiogenesis; it binds to both VEGFR-1 and VEGFR-2. The inhibition of angiogenesis by obstructing VEGF-A signaling has been investigated as a method to treat solid tumors, but the development of resistance to this blockade has complicated treatment. The major mechanisms of this resistance to VEGF-A blockade include signaling by redundant receptors, such as the fibroblast growth factors, angiopoietin-1, ephrins, and other forms of VEGF. Other major mechanisms of resistance are increased metastasis of hypoxia-resistant tumor cells, recruitment of cell types capable of promoting VEGF-independent angiogenesis, and increased circulation of nontumor proangiogenic factors. Additional mechanisms of resistance to VEGF-A blockade include heterogeneity of responsiveness among tumor cells, use of anti-VEGF-A agents at insufficient doses or for insufficient duration, altered sensitivity to anti-VEGF-A agents by mutations in endothelial cells or vascular remodeling, maintenance of vascular sleeves that allow for easy regrowth of tumor vasculature upon discontinuation of therapy, vascular cooption, and intussusceptive angiogenesis. An understanding of these mechanisms may lead to the development of targeted therapies that overcome this resistance. Some of these approaches include the combined inhibition of redundant angiogenic pathways, proper patient selection for various therapies based on gene expression profiles, blockade of cellular migration by inhibition of colony-stimulating factor, or the use of agents to disrupt vascular architecture.

Osteopontin as a key mediator for vasculogenic mimicry in hepatocellular carcinoma

Osteopontin (OPN) is overexpressed in a variety of cancers including hepatocellular carcinoma (HCC), and is likely involved in the process of vasculogenic mimicry (VM) in some tumor cells. In this study, we explored whether OPN plays a role for VM in HCC. Metastatic MHCC97-H human HCC cells and non-metastatic Hep3B human HCC cells were compared for their abilities to establish VM. Three dimensional-culture assays showed that MHCC97-H cells but not Hep3B cells were able to form the chord-like structure that represents VM. Real-time RT-PCR arrays were used to detect gene expression profiles of the two HCC cell lines in three-dimensional culture. PCR array analyses revealed the increased expression of OPN in MHCC97-H cells forming VM compared with Hep3B cells. Small interfering RNA was employed to investigate whether OPN knockdown could influence VM, and the expression of matrix metalloproteinase (MMP)-2, MMP-9 and urokinase-type plasminogen activator (uPA) in MHCC97-H cells. OPN knockdown resulted in a significant decrease in the ability of MHCC97-H cells to form VM, which was accompanied by the down-regulation of MMP-2 and uPA expression. Furthermore, human HCC tissue samples were studied by immunohistochemistry to analyze the correlations between VM and the expression of OPN, MMP-2 and uPA. There existed significant positive correlations between VM and the expression of OPN, MMP-2 and uPA in HCC tissue samples. In conclusion, OPN is required for VM in HCC cells, and its action may be associated with activation of MMP-2 and uPA. OPN-targeted therapeutics may be useful for patients with advanced HCC.

Celastrus orbiculatus extract inhibits tumor angiogenesis by targeting vascular endothelial growth factor signaling pathway and shows potent antitumor activity in hepatocarcinomas in Vitro and in Vivo

OBJECTIVE

Celastrus orbiculatus Thunb. has been used for thousands of years in China as a remedy against cancer and inflammatory diseases. This study aims to investigate whether C. orbiculatus extract (COE) could inhibit angiogenesis, which is the pivotal step in tumor growth, invasiveness, and metastasis.

METHODS

In this study, the extract from the stem of C. orbiculatus was used. Mouse hepatic carcinoma cells (Hepa1-6) were treated with COE in different nontoxic concentrations (10, 20, 40, 80, and 160 μg/mL). The mRNA and protein expression levels of vascular endothelial growth factor (VEGF) were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively; the active fractions were further tested on C57BL/6 mice and human umbilical vein endothelial cells (HUVEC) for any antiangiogenic effects.

RESULTS

COE significantly inhibited proliferation and induced apoptosis in Hepa1-6 cells and inhibited VEGF expression at both mRNA and protein levels. Furthermore, this agent inhibited the formation of the capillary-like structure in primary cultured HUVEC in a dose-dependent manner. In vivo, COE significantly reduced the volume and weight of solid tumors with low adverse effects and decreased tumor angiogenesis.

CONCLUSIONS

In summary, COE could be used to treat hepatic carcinoma. The mechanisms of the antitumor activity of COE may be due to its effects against tumor angiogenesis by targeting the VEGF protein.

Vaccines targeting the neovasculature of tumors

Angiogenesis has a critical role in physiologic and disease processes. For the growth of tumors, angiogenesis must occur to carry sufficient nutrients to the tumor. In addition to growth, development of new blood vessels is necessary for invasion and metastases of the tumor. A number of strategies have been developed to inhibit tumor angiogenesis and further understanding of the interplay between tumors and angiogenesis should allow new approaches and advances in angiogenic therapy. One such promising angiogenic approach is to target and inhibit angiogenesis with vaccines. This review will discuss recent advances and future prospects in vaccines targeting aberrant angiogenesis of tumors. The strategies utilized by investigators have included whole endothelial cell vaccines as well as vaccines with defined targets on endothelial cells and pericytes of the developing tumor endothelium. To date, several promising anti-angiogenic vaccine strategies have demonstrated marked inhibition of tumor growth in pre-clinical trials with some showing no observed interference with physiologic angiogenic processes such as wound healing and fertility.

Pigment epithelium-derived factor as an anticancer drug and new treatment methods following the discovery of its receptors: a patent perspective

Traditional forms of cancer therapy, which include chemotherapy, have largely been overhauled due to the significant degree of toxicity they pose to normal, otherwise healthy tissue. It is hoped that the use of biological agents, most of which are endogenously present in the body, will lead to safer treatment outcomes, without sacrificing efficacy. The finding that pigment epithelium-derived factor (PEDF), a naturally-occurring protein, is a potent angiogenesis inhibitor has become the basis for studying the role of PEDF in tumours that are highly resistant to chemotherapy. The determination of the direct role of PEDF against cancer paves the way for understanding and developing PEDF as a novel drug. This review focuses on the patent applications behind testing the anticancer therapeutic effect of PEDF via its receptors as an antiangiogenic agent and as a direct anticancer agent. The majority of the PEDF patents describe the antiangiogenic ability and usage of recombinant vectors as the mode of treatment delivery. PEDF's therapeutic potential against different diseases and the discovery of its receptors open possibilities for improving PEDF-based peptide design and drug delivery modes.

Derived vascular endothelial cells induced by mucoepidermoid carcinoma cells: 3-dimensional collagen matrix model

Mucoepidermoid carcinoma undergoes uniquely vigorous angiogenic and neovascularization processes, possibly due to proliferation of vascular endothelial cells (ECs) induced by mucoepidermoid carcinoma cells (MCCs) in their three-dimensional (3D) microenvironment. To date, no studies have dealt with tumor cells and vascular ECs from the same origin of mucoepidermoid carcinoma using the in vitro 3D microenvironment model. In this context, the current research aims to observe neovascularization with mucoepidermoid carcinoma microvascular ECs (MCMECs) conditioned by the microenvironment in the 3D collagen matrix model. We observed the growth of MCMECs purified by immunomagnetic beads and induced by MCCs, and characteristics of tubule-like structures (TLSs) formed by induced MCMECs or non-induced MCMECs. The assessment parameters involved the growth curve, the length, the outer and inner diameters, and the wall thickness of the TLSs, and the cell cycle. Results showed that MCCs induced formation of the TLSs in the 3D collagen matrix model. A statistically significant difference was noted regarding the count of TLSs between the control group and the induction group on the 4th day of culture (t=5.00, P=0.001). The outer and inner diameters (t(1)=5.549, P(1)=0.000; t(2)=10.663, P(2)=0.000) and lengths (t=18.035, P=0.000) of the TLSs in the induction group were statistically significant larger than those in the control group. The TLSs were formed at the earlier time in the induction group compared with the control group. It is concluded that MCCs promote growth and migration of MCMECs, and formation of the TLSs. The 3D collagen matrix model with MCMECs induced by MCCs in the current research may be a favorable choice for research on pro-angiogenic factors in progression of mucoepidermoid carcinoma.

Pigment epithelium-derived factor as an impending therapeutic agent against vascular epithelial growth factor-driven tumor-angiogenesis

In spite of the recent epidemiological study indicating a positive decrease in cancer trends, cancer remains to be one of the major causes of deaths and there is an anticipated increase in the number of new cancer cases to be recorded in the following years to come. It is important for researchers to improve the current therapeutic agents involved against cancer, particularly targeting to inhibit tumor cell growth, survival, and metastasis. Many researchers investigate the crucial role of a proangiogenic factor, vascular endothelial growth factor (VEGF) in the process of tumor angiogenesis, where the formation of new blood vessels carrying essential nutrients to the tumor cell becomes a critical factor for tumor growth. Since the establishment of VEGF's integral role in mediating tumor angiogenesis and tumor cell survival, current efforts are dedicated to developing therapeutic agents against VEGF and one of the emerging candidate under this category is pigment epithelium-derived factor (PEDF).

Inorganic nanoparticle-based contrast agents for molecular imaging

Inorganic nanoparticles (NPs) including semiconductor quantum dots (QDs), iron oxide NPs and gold NPs have been developed as contrast agents for diagnostics by molecular imaging. Compared with traditional contrast agents, NPs offer several advantages: their optical and magnetic properties can be tailored by engineering the composition, structure, size and shape; their surfaces can be modified with ligands to target specific biomarkers of disease; the contrast enhancement provided can be equivalent to millions of molecular counterparts; and they can be integrated with a combination of different functions for multimodal imaging. Here, we review recent advances in the development of contrast agents based on inorganic NPs for molecular imaging, and also touch on contrast enhancement, surface modification, tissue targeting, clearance and toxicity. As research efforts intensify, contrast agents based on inorganic NPs that are highly sensitive, target-specific and safe to use are expected to enter clinical applications in the near future.

The role of angiogenesis in the transformation of plexiform neurofibroma into malignant peripheral nerve sheath tumors in children with neurofibromatosis type 1

PURPOSE

The role of angiogenesis in the transformation of peripheral neurofibroma (PNF) to malignant peripheral nerve sheath tumor (MPNST) in neurofibromatosis type 1 (NF1) remains elusive and forms the objective of this study.

EXPERIMENTAL DESIGN

Archival tissue from 5 children with NF1 and PNF, who developed MPNST between the ages of 8 and 15 years were analyzed for differences in microvasculature. The role of proangiogenic growth factors such as Vascular Endothelial Growth Factor (VEGF), and its receptors Flk-1 and Flt-1, and vessel maturity, defined as von Willebrand factor (vWf), α-smooth muscle actin+ (SMA+), were evaluated by immuno-histochemistry.

RESULTS

A qualitative evaluation of the vasculature showed predominantly α-SMA+/vWf+ more stable vessels in PNF, and an irregular meshwork of α-SMA-/vWf+ endothelial cells structures in MPNST. In NF and PNF tumor cells were VEGF-, in contrast to VEGF+ tumor cells in MPNST. If present, the VEGF stain was confined mainly to the perivascular spaces in PNF, unlike the mainly stromal VEGF stain in MPNST. VEGF receptors also manifested a tumor stage-specific pattern. Flk-1 and Flt-1 were restricted to the mature, well-formed vasculature in PNF, but exhibited a diffuse pattern in MPNST.

CONCLUSION

Our study provides a rare opportunity to document consistent and histologically detectable differences in the vascular organization of PNF and MPNST. It permits a pair-wise evaluation of the malignant conversion of benign PNF into its malignant counterpart, in the same patients. The phenotypic variations and characteristics of the vessels in these tumors are consistent with the idea that a strong proangiogenic drive contributes to the progressive growth in MPNST.

Eph receptors and ephrin ligands: important players in angiogenesis and tumor angiogenesis

Eph receptors and their ephrin ligands were identified in the late 1980's. Subsequently, they were linked to different physiological and pathophysiological processes like embryonic development, angiogenesis, and tumorigenesis. In this regard, recent work focused on the distribution and effects of Eph receptors and ephrins on tumor cells and tumor microenvironment. The purpose of this review is to outline the role of these molecules in physiological angiogenesis and pathophysiological tumor angiogenesis. Furthermore, novel therapeutical approaches are discussed as Eph receptors and ephrins represent attractive targets for antiangiogenic therapy.

Ascorbate inhibition of angiogenesis in aortic rings ex vivo and subcutaneous Matrigel plugs in vivo

Background

Angiogenesis is critical to tumor growth and is therefore a potential target for cancer therapy. As many current inhibitors of angiogenesis exhibit host toxicity, natural alternatives are needed. At millimolar concentrations, ascorbate (vitamin C) inhibits migration and tubule formation by mature endothelial cells and endothelial progenitors. In the present study, we examined the effects of ascorbate, at levels relevant during intravenous infusion therapy, on angiogenesis using an ex vivo an in vivo assay.

Methods

Two assays were used to evaluate effect of high-doses ascorbic acid on angiogenesis: ex vivo rat aortic ring explant assay in Matrigel matrices and in vivo Matrigel plug assay. In aortic rings, we quantified microvessel growth, branching and vessel regression under different treatment conditions. In murine angiogenesis assay, male C57 mice 6-8 weeks old were treated by high-dose ascorbic acid and the number of microvessels was analyzed by histological method. To characterize the population of cells that formed capillary network and microvessels, the sections were stained by CD34 and CD31 antibodies.

Results

Results show that sprouting of endothelial tubules from aortic rings was reduced in a concentration-dependent fashion by ascorbate: while controls roughly tripled sprout densities during the study, ascorbate (1 mg/mL, 5.5 mM) actually reduced sprout density. In vivo, the ability of mice to vascularize subcutaneously implanted Matrigel plug was diminished if the mice were treated with 430 mg/kg vitamin C: numbers of vessels, and vessel densities, in plugs from treated mice were roughly 30% less than those in plugs from untreated mice.

Conclusions

We conclude that the inhibition of angiogenesis by ascorbate suggested in vitro is confirmed in vivo, and that angiogenesis inhibition may be one mechanism by which intravenous ascorbate therapy shows efficacy in animal experiments and clinical case studies.

Urinary angiostatin levels are elevated in patients with epithelial ovarian cancer

OBJECTIVE

The poor prognosis associated with epithelial ovarian cancer (EOC) is due to the lack of overt early symptoms and the absence of reliable diagnostic screening methods. Since many tumors over express angiogenic regulators, the purpose of this study was to determine whether elevated levels of the angiogenic or angiostatic molecules vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), endostatin (ES), and angiostatin (AS) were elevated in plasma and urine from patients with EOC.

METHODS

VEGF, HGF, ES and AS were assayed by ELISA in samples from pilot cohort consisting of healthy women (N=48; pre-menopausal N=23, post-menopausal N=25), women with benign gynecological disease (N=54), patients with primary peritoneal cancer (PP) (N=2) and EOC (N=35). Wherever possible, parallel serum samples were measured for CA125 levels by ELISA.

RESULTS

AS was the angioregulator that independently discriminated EOC patients from healthy individuals. Levels of urinary AS (uAS) from healthy individuals or women with benign gynecological disease averaged 21.4 ng/mL+/-3.7 and 41.5 ng/mL+/-8.8, respectively. In contrast, uAS averaged 115 ng/mL+/-39.2 and 276 ng/mL+/-45.8 from women with Stage I (N=6) and late stage (N=31) EOC, respectively. Furthermore, uAS was elevated in EOC patients regardless of tumor grade, stage, size, histological subtype, creatinine levels, menopausal status, or patient age, but appeared to complement CA125 measurements.

CONCLUSIONS

Levels of AS are elevated in the urine of patients with EOC and may be of diagnostic and/or prognostic clinical importance. Further studies of uAS as a biomarker for EOC alone or in combination with other markers are warranted.

Bisphosphonates suppress insulin-like growth factor 1-induced angiogenesis via the HIF-1alpha/VEGF signaling pathways in human breast cancer cells

Adjunctive chemotherapy with bisphosphonates has been reported to delay bone metastasis and improve overall survival in breast cancer. Aside from its antiresorptive effect, bisphosphonates exhibit antitumor activities, in vitro and in vivo, via several mechanisms, including antiangiogenesis. In this study, we investigated the potential molecular mechanisms underlying the antiangiogenic effect of non-nitrogen-containing and nitrogen-containing bisphosphonates, clodronate and pamidronate, respectively, in insulin-like growth factor (IGF)-1 responsive human breast cancer cells. We tested whether bisphosphonates had any effects on hypoxia-inducible factor (HIF)-1alpha/vascular endothelial growth factor (VEGF) axis that plays a pivotal role in tumor angiogenesis, and our results showed that both pamidronate and clodronate significantly suppressed IGF-1-induced HIF-1alpha protein accumulation and VEGF expression in MCF-7 cells. Mechanistically, we found that either pamidronate or clodronate did not affect mRNA expression of HIF-1alpha, but they apparently promoted the degradation of IGF-1-induced HIF-1alpha protein. Meanwhile, we found that the presence of pamidronate and clodronate led to a dose-dependent decease in the newly-synthesized HIF-1alpha protein induced by IGF-1 in breast cancer cells after proteasomal inhibition, thus, indirectly reflecting the inhibition of protein synthesis. In addition, our results indicated that the inhibitory effects of bisphosphonates on the HIF-1alpha/VEGF axis are associated with the inhibition of the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin signaling pathways. Consistently, we demonstrated that pamidronate and clodronate functionally abrogated both in vitro and in vivo tumor angiogenesis induced by IGF-1-stimulated MCF-7 cells. These findings have highlighted an important mechanism of the pharmacological action of bisphosphonates in the inhibition of tumor angiogenesis in breast cancer cells.

Von Hippel-Lindau gene product modulates TIS11B expression in renal cell carcinoma: impact on vascular endothelial growth factor expression in hypoxia

TIS11B belongs to a group of RNA-binding proteins (including TIS11/tristetraprolin and TIS11D) that share characteristic tandem CCCH-type zinc-finger domains and can be rapidly induced by multiple stimuli. TIS11B has been shown to regulate vascular endothelial growth factor (VEGF) mRNA stability in adrenocorticotropic hormone-stimulated primary adrenocortical cells. TIS11B has also been documented as a negative regulator of VEGF during development, but nothing has yet been reported in the context of human cancers. The Von Hippel-Lindau (VHL) tumor suppressor protein regulates VEGF gene expression at both the transcriptional and post-transcriptional levels in normoxia. However, whether it can do so in hypoxia is still unclear. Here, we report a unique regulatory function of VHL in VEGF expression in hypoxia that is mediated through modulation of TIS11B protein levels in renal cancer cells. In normoxia, we detected increased expression of the microRNA hsa-miR-29b in the VHL-overexpressing renal cancer cell line 786-O. We also show that this increased expression of hsa-miR-29b decreased TIS11B protein expression by post-transcriptional regulation in normoxia. In contrast, in hypoxia, increased TIS11B expression paralleled an increased TIS11B mRNA stability in VHL-overexpressing 786-O cells. This VHL-mediated TIS11B up-regulation in hypoxia may be important for TIS11B-regulated gene expression: we observed a down-regulation of VEGF mRNA in hypoxia in VHL-overexpressing cells compared with parental 786-O cells, and this effect was reversible by silencing TIS11B expression.

Active targeting schemes for nanoparticle systems in cancer therapeutics

The objective of this review is to outline current major cancer targets for nanoparticle systems and give insight into the direction of the field. The major targeting strategies that have been used for the delivery of therapeutic or imaging agents to cancer have been broken into three sections. These sections are angiogenesis-associated targeting, targeting to uncontrolled cell proliferation markers, and tumor cell targeting. The targeting schemes explored for many of the reported nanoparticle systems suggest the great potential of targeted delivery to revolutionize cancer treatment.

Biology and potential clinical implications of tissue inhibitor of metalloproteinases-1 in colorectal cancer treatment

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the industrialized world. About half of "curatively" resected patients develop recurrent disease within the next 3-5 years despite the lack of clinical, histological and biochemical evidence of remaining overt disease after resection of the primary tumour. Availability of validated biological markers for early detection, selection for adjuvant therapy, prediction of treatment efficacy and monitoring of treatment efficacy would most probably increase survival. Tissue inhibitor of metalloproteinases-1 (TIMP-1) may be such a marker. TIMP-1 inhibits the proteolytic activity of metalloproteinases, which are centrally involved in tumour invasion and metastases. However, in clinical investigations high tumour tissue or plasma levels of TIMP-1 have shown a strong and independent association with a shorter survival time in CRC patients, suggesting that TIMP-1 could have a tumour-promoting function. Furthermore, measurement of plasma TIMP-1 has been shown to be useful for disease detection, with a high sensitivity and high specificity for early-stage colon cancer. This review describes some basic information on the current knowledge of the biology of TIMP-1 as well as the potential use of TIMP-1 as a biological marker in the management of CRC patients.

Cancer gene therapy with iCaspase-9 transcriptionally targeted to tumor endothelial cells

Antiangiogenic therapies have shown varying results partly because each tumor type secretes a distinct panel of angiogenic factors to sustain its own microvascular network. In addition, recent evidence demonstrated that tumors develop resistance to antiangiogenic therapy by turning on alternate angiogenic pathways when one pathway is therapeutically inhibited. Here, we test the hypothesis that expression of a caspase-based artificial death switch in tumor-associated endothelial cells will disrupt tumor blood vessels and slow down tumor progression irrespective of tumor type. Adenoviral vectors expressing inducible Caspase-9 (iCaspase-9) under transcriptional regulation with the endothelial cell-specific vascular endothelial growth factor receptor-2 (VEGFR2) promoter (Ad-hVEGFR2-iCaspase-9) induced apoptosis of proliferating human dermal microvascular endothelial cells (HDMECs), but not human tumor cells (UM-SCC-17B, head and neck squamous cell carcinoma; HepG2, hepatocellular carcinoma; PC-3, prostate adenocarcinoma; SLK, Kaposi's sarcoma; MCF-7, breast adenocarcinoma). Notably, apoptosis was dependent upon activation of iCaspase-9 with the dimerizer drug AP20187. Local delivery of Ad-hVEGFR2-iCaspase-9 followed by intraperitoneal injection of AP20187 ablated tumor microvessels and inhibited xenografted tumor growth in all tumor models evaluated here. We conclude that a cancer gene therapy strategy based on a transcriptionally targeted viral vector expressing an inducible caspase allows for selective and controlled ablation of microvessels of histopathologically diverse tumor types.