Tumor-associated Angiogenesis Research Articles

Exosome-Based Cell-Cell Communication in the Tumor Microenvironment.

Tumors are not isolated entities, but complex systemic networks involving cell-cell communication between transformed and non-transformed cells. The milieu created by tumor-associated cells may either support or halt tumor progression. In addition to cell-cell contact, cells communicate through secreted factors via a highly complex system involving characteristics such as ligand concentration, receptor expression and integration of diverse signaling pathways. Of these, extracellular vesicles, such as exosomes, are emerging as novel cell-cell communication mediators in physiological and pathological scenarios. Exosomes, membrane vesicles of endocytic origin released by all cells (both healthy and diseased), ranging in size from 30 to 150 nm, transport all the main biomolecules, including lipids, proteins, DNAs, messenger RNAs and microRNA, and perform intercellular transfer of components, locally and systemically. By acting not only in tumor cells, but also in tumor-associated cells such as fibroblasts, endothelium, leukocytes and progenitor cells, tumor- and non-tumor cells-derived exosomes have emerged as new players in tumor growth and invasion, tumor-associated angiogenesis, tissue inflammation and immunologic remodeling. In addition, due to their property of carrying molecules from their cell of origin to the peripheral circulation, exosomes have been increasingly studied as sources of tumor biomarkers in liquid biopsies. Here we review the current literature on the participation of exosomes in the communication between tumor and tumor-associated cells, highlighting the role of this process in the setup of tumor microenvironments that modulate tumor initiation and metastasis.

BMP-2 induces angiogenesis by provoking integrin α6 expression in human endothelial progenitor cells

Bone morphogenetic protein-2 (BMP-2) is a multifunctional cytokine, capable of governing several cellular functions, including proliferation, motility, differentiation, and angiogenesis. Circulating endothelial progenitor cells (EPCs) have been shown to facilitate tissue repair, postnatal neovascularization, and tumor associated angiogenesis. Nevertheless, the impact of BMP-2 on angiogenesis of human EPCs has largely remained a mystery. In this study, we found that BMP-2 promoted cell migration and tube formation of EPCs in a concentration-dependent manner, indicating BMP-2 induced in vitro angiogenesis in human EPCs. Furthermore, BMP-2 significantly increased microvessel formation in Matrigel plug assay, and BMP-2 antagonist noggin prevented BMP-2-induced in vivo angiogenesis. Mechanistic investigations showed BMP-2 profoundly induced the expression of Id-1 and integrin α6 as well as EPCs angiogenesis by activating PI3K/Akt and MEK/ERK signaling pathways. Moreover, knockdown of Id-1 and integrin α6 by siRNA transfection obviously attenuated BMP-2-indueced tube formation of EPCs. These results suggest that BMP-2 promotes angiogenesis in human EPCs through the activation of PI3K/Akt, MEK/ERK, and Id-1/integrin α6 signaling cascades. This is the first demonstration that BMP-2 exhibits the angiogenesis property on human EPCs. BMP-2 might serve as the potential therapeutic target for treatment of angiogenesis-related diseases.

Abstract P3-05-16: A mathematical model for predicting immune response in a trastuzumab treated HER2+ breast cancer animal model: Preliminary efforts

Abstract Introduction: Trastuzumab is a targeted antibody to the human epidermal growth factor receptor 2 (HER2) that induces cell cycle arrest and is used in the treatment of HER2+ positive breast cancer. We have recently presented in vivo evidence in a murine model that trastuzumab also improves vascular delivery of subsequent cytotoxic therapies. The mechanism by which trastuzumab and the immune system interact to regulate tumor-associated angiogenesis is not well characterized. Therefore, we offer a preliminary report on a mathematical framework to systematically investigate the potential interactions among the immune response, tumor cells, vasculature, and other environmental factors based on experimental data for the BT474 murine model of HER2+ breast cancer. Experimental: BT474 breast cancer cells were implanted subcutaneously into athymic nude mice. After tumors reached 250 mm3, mice were treated with trastuzumab or saline, tumor volumes were recorded, and tumors were extracted at various times over seven days. Immunohistochemistry for treated and control tumors were evaluated for 0, 1, 3, 4, and 7 days post trastuzumab treatment. Histology data includes: percent hypoxia (pimonidazole), percent necrosis, and vascular maturation index (VMI, ratio of alpha-smooth muscle actin to total vessel counts as stained with CD31). Ongoing studies are quantifying immune cell infiltration through immunofluorescent imaging of F4/80 and CD11c expression. Modeling: We developed a system of five coupled, ordinary differential equations that accounts for the temporal variation in tumor growth, vasculature, hypoxia, necrosis, and immune response. The general immune response component corresponds to the mouse's pro-inflammatory responses, as T cell driven responses are absent in this murine model. Uncertainty analysis was performed to verify plausible overlap between the model's predictions and the experimental data—where local and global samplings of all parameters were used to generate potential model results to be compared to the data for both control and treated mouse sets. Sensitivity analysis was performed using Sobol' Indices to determine the driving parameters of the system to identify target parameters for experimental estimation. The model parameters were calibrated using mean and standard deviations for the available data (tumor volume, VMI, percentage of hypoxia, and percentage of necrosis) for each experimental time point to predict the differences of the immune component between the treated and control tumors. Results and Discussion: The model is well behaved and can be calibrated with the available data. The model predicts distinct differences for the immune response between the control and treated groups—showing increasing versus decreasing immune component values over time for treated versus control results, respectively. Preliminary results from the immunofluorescent imaging data support the immunological predictions of the model; in particular, the amount of immune infiltration (i.e., more immune cells) in necrotic areas is greater in the treated than the untreated tumors (p<0.025). We acknowledge the support of CPRIT RR160005 and NCI R01CA186193. Citation Format: Jarrett AM, Yankeelov TE, Ehrlich LI, Godfrey W, Sorace AG. A mathematical model for predicting immune response in a trastuzumab treated HER2+ breast cancer animal model: Preliminary efforts [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-16.

Biophysical evidence for differential gallated green tea catechins binding to membrane type-1 matrix metalloproteinase and its interactors

Membrane type-1 matrix metalloproteinase (MT1-MMP) is a transmembrane MMP which triggers intracellular signaling and regulates extracellular matrix proteolysis, two functions that are critical for tumor-associated angiogenesis and inflammation. While green tea catechins, particularly epigallocatechin gallate (EGCG), are considered very effective in preventing MT1-MMP-mediated functions, lack of structure-function studies and evidence regarding their direct interaction with MT1-MMP-mediated biological activities remain. Here, we assessed the impact in both cellular and biophysical assays of four ungallated catechins along with their gallated counterparts on MT1-MMP-mediated functions and molecular binding partners. Concanavalin-A (ConA) was used to trigger MT1-MMP-mediated proMMP-2 activation, expression of MT1-MMP and of endoplasmic reticulum stress biomarker GRP78 in U87 glioblastoma cells. We found that ConA-mediated MT1-MMP induction was inhibited by EGCG and catechin gallate (CG), that GRP78 induction was inhibited by EGCG, CG, and gallocatechin gallate (GCG), whereas proMMP-2 activation was inhibited by EGCG and GCG. Surface plasmon resonance was used to assess direct interaction between catechins and MT1-MMP interactors. We found that gallated catechins interacted better than their ungallated analogs with MT1-MMP as well as with MT1-MMP binding partners MMP-2, TIMP-2, MTCBP-1 and LRP1-clusterIV. Overall, current structure-function evidence supports a role for the galloyl moiety in both direct and indirect interactions of green tea catechins with MT1-MMP-mediated oncogenic processes.

Endoglin interacts with VEGFR2 to promote angiogenesis.

Endoglin, a TGF-β coreceptor predominantly expressed in endothelial cells, plays an important role in vascular development and tumor-associated angiogenesis. However, the mechanism by which endoglin regulates angiogenesis, especially during tip cell formation, remains largely unknown. In this study, we report that endoglin promoted VEGF-induced tip cell formation. Mechanistically, endoglin interacted with VEGF receptor (VEGFR)-2 in a VEGF-dependent manner, which sustained VEGFR2 on the cell surface and prevented its degradation. Endoglin mutants deficient in the ability to interact with VEGFR2 failed to sustain VEGFR2 on the cell surface and to promote VEGF-induced tip cell formation. Further, an endoglin-targeting monoclonal antibody (mAb), TRC105, cooperated with a VEGF-A targeting mAb, bevacizumab, to inhibit VEGF signaling and tip cell formation in vitro and to inhibit tumor growth, metastasis, and tumor-associated angiogenesis in a murine tumor model. This study demonstrate a novel mechanism by which endoglin initiates and regulates VEGF-driven angiogenesis while providing a rationale for combining anti-VEGF and anti-endoglin therapy in patients with cancer.-Tian, H., Huang, J. J., Golzio, C., Gao, X., Hector-Greene, M., Katsanis, N., Blobe, G. C. Endoglin interacts with VEGFR2 to promote angiogenesis.

Tumor associated macrophages and angiogenesis dual-recognizable nanoparticles for enhanced cancer chemotherapy

Tumor-associated macrophages (TAMs) and angiogenesis are increasingly considered as the pivotal factors that affect tumor progress. Herein, we developed the paclitaxel (PTX)-loaded nanoparticles (NP/PTX) and decorated it with an innovative peptide YI (YINP/PTX) for simultaneously targeting delivery of drug to TAMs and angiogenesis. We demonstrated that the modification of YI peptide significantly enhanced the internalization of nanoparticles by cells and accumulation of nanoparticles in tumor tissues, but down regulated the distribution of them in normal tissues especially the liver. We also made a confirmation that the YI peptide decorated nanoparticles had an excellent co-localization with TAMs and angiogenesis in vivo. Finally, in the HT-26 colorectal tumor-bearing mice, a pharmacodynamic evaluation was performed and results showed that the YINP/PTX was more effective than other PTX formulations in anti-tumor growth. These results together suggested that the prepared nanoparticles are promising in targeting delivery of chemotherapeutics to tumor microenvironment for enhancing tumor therapy effect.

Role of dalteparin sodium on the growth of cancer cells and tumor-associated angiogenesis in A549 human lung cancer cell line and grafted mouse model.

To investigate the effects of dalteparin sodium on the expression of vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and hypoxia-inducible factor 1α (HIF-1α) in A549 human lung cancer (LC) cell line and a human A549-grafted nude mouse model. A549 human lung adenocarcinoma cell line was divided into control group, treated using normal saline (NS); and dalteparin sodium groups, receiving 5, 15, 50, and 150 IU/ml of dalteparin sodium, respectively. Human A549-grafted nude mouse was induced through subcutaneous (SC) injection of A549 (5 × 106/0.2 ml) into the right armpit, and randomly assigned into control group (n = 6) receiving intraperitoneal (i.p.) injection of NS, cisplatin (DDP) group (n = 6, 3 mg/kg DDP alone, i.p., for 3 days), low molecular weight heparin (LMWH) group (n = 6) receiving SC injection of 1500 IU/kg dalteparin sodium for 35 days, and DDP plus LMWH group (n = 6, 3 mg/kg DDP, i.p., for 3 days, followed by SC injection of 1500 IU/kg dalteparin sodium for 35 days). Significant difference was noted in the messenger RNA expression of VEGF, VEGFR, and HIF-1α after treating with heparin with a concentration of 15, 50, or 150 IU/ml in the A549 cell line at 24 and 48 h, respectively. In the human A549-grafted nude mouse model, a significant reduction was noted in the expression of VEGF, VEGFR, and HIF-1α in the tumor mass harvested from the mice receiving administration of dalteparin sodium plus DDP. Dalteparin sodium had the inhibitory effects on the growth of human LC A549 cells in vitro and A549 LC xenograft model, which could be enhanced when administrated together with DDP.

Anti-angiogenic and anti-inflammatory effects of long-circulating liposomes co-encapsulating curcumin and doxorubicin on C26 murine colon cancer cells.

Emerging treatment options for colon cancer are needed to overcome the limitations regarding the side effects of current chemotherapeutics and drug resistance. The goal of this study was to assess the antitumor actions of PEGylated long-circulating liposomes (LCL) co-delivering curcumin (CURC) and doxorubicin (DOX) on murine colon carcinoma cells (C26). The cytotoxicity of CURC and DOX, administered alone or in combination, either in free or LCL form, was evaluated with regard to antiproliferative effects on C26 cells and to protumor processes that might be affected. Our results indicated that PEGylated LCL-CURC-DOX exerted strong antiproliferative effects on C26 cells, slightly exceeding those induced by free CURC-DOX, but higher than either agent administered alone in their free form. These effects of LCL-CURC-DOX were due to the inhibition of the production of angiogenic/inflammatory proteins in a NF-κB-dependent manner, but were independent of ROS production or AP-1 c-Jun activation. Notable, the anti-angiogenic actions of LCL-CURC-DOX appeared to be much stronger than those induced by the co-administration of CURC and DOX in their free form, on C26 colon cancer cells. LCL-CURC-DOX demonstrated enhanced cytotoxicity on C26 murine colon cancer cells by inhibiting the production of the majority of factors involved in tumor-associated angiogenesis and inflammation and is now being evaluated in vivo regarding its efficacy towards tumor growth in colon cancer.

Celecoxib normalizes the tumor microenvironment and enhances small nanotherapeutics delivery to A549 tumors in nude mice

Barriers presented by the tumor microenvironment including the abnormal tumor vasculature and interstitial matrix invariably lead to heterogeneous distribution of nanotherapeutics. Inspired by the close association between cyclooxygenase-2 (COX-2) and tumor-associated angiogenesis, as well as tumor matrix formation, we proposed that tumor microenvironment normalization by COX-2 inhibitors might improve the distribution and efficacy of nanotherapeutics for solid tumors. The present study represents the first time that celecoxib, a special COX-2 inhibitor widely used in clinics, was explored to normalize the tumor microenvironment and to improve tumor nanotherapeutics delivery using a human-derived A549 tumor xenograft as the solid tumor model. Immunofluorescence staining of tumor slices demonstrated that oral celecoxib treatment at a dose of 200 mg/kg for two weeks successfully normalized the tumor microenvironment, including tumor-associated fibroblast reduction, fibronectin bundle disruption, tumor vessel normalization, and tumor perfusion improvement. Furthermore, it also significantly enhanced the in vivo accumulation and deep penetration of 22-nm micelles rather than 100-nm nanoparticles in tumor tissues by in vivo imaging and distribution experiments and improved the therapeutic efficacy of paclitaxel-loaded micelles in tumor xenograft-bearing mouse models in the pharmacodynamics experiment. As celecoxib is widely and safely used in clinics, our findings may have great potential in clinics to improve solid tumor treatment.

Zoledronic acid inhibits infiltration of tumor-associated macrophages and angiogenesis following transcatheter arterial chemoembolization in rat hepatocellular carcinoma models.

Hepatic transcatheter arterial chemoembolization (TACE), a minimally invasive procedure to block the blood supply of tumors and release of cytotoxic agents, is preferentially applied to patients with hepatocellular carcinoma (HCC) who are not able to receive radical treatments. However, the long-term effects of TACE are unsatisfactory, as the microenvironment following procedure stimulates tumor angiogenesis, which promotes recurrence and metastasis of residual tumors. Tumor associated macrophages (TAMs) have been revealed to stimulate tumor growth and angiogenesis associated with poor prognosis in HCC. The present study focused on the changes in TAMs following TACE, and explored the effects of TACE in combination with the TAM inhibitor zoledronic acid (ZA) in rat HCC models. Orthotropic HCC rats were divided into three groups: Sham TACE, TACE alone and TACE combined with ZA treatment. At 7 or 14 days following TACE, tumor growth was evaluated by magnetic resonance imaging (MRI). Infiltration of TAMs was assessed by histological analysis and flow cytometry. Tumor angiogenesis was measured as the mean vessel density, and initial slope was calculated from dynamic contrast enhancement MRI. Local and systemic levels of vascular endothelial growth factor (VEGF) were determined by western blotting or an ELISA, respectively. The results revealed that TACE inhibited tumor growth at 7 days following the procedure, but this inhibition was attenuated at 14 days following the procedure compared with the sham TACE control. If combined with ZA treatment, TACE exhibited a stable inhibition effect on tumor growth until the end of observation. Investigation of the underlying mechanisms demonstrated that TACE combined with ZA treatment inhibited infiltration of F4/80 positive TAMs and tumor angiogenesis compared with the TACE alone group at 14 days following the procedure. Additionally, the combination treatment significantly inhibited secretion of VEGF in the present models. In conclusion, ZA treatment enhanced the effects of TACE through inhibiting TAM infiltration and tumor angiogenesis in rat HCC models.

The Prostaglandin EP3 Receptor Is an Independent Negative Prognostic Factor for Cervical Cancer Patients.

We know that one of the main risk factors for cervical cancer is an infection with high-risk human papillomavirus (HR-HPV). Prostaglandins and their receptors are very important for the tumour growth and tumour-associated angiogenesis. Little is known about the expression of the Prostaglandin E receptor type 3 (EP3) or the Prostaglandin (PG)E2-EP3 signalling in cervical cancer, so the aim of the study was to analyse the expression of the EP3 receptor in cervical cancer and find prognostic factors in relation to survival; EP3 immunohistological staining of 250 cervical cancer slides was performed and analysed with a semi-quantitative score. The statistical evaluation was performed with Statistical Package for the Social Sciences (SPSS) to evaluate the staining results and the survival analyses of the cervical cancer cases. A significant difference was observed in EP3 expression in Fédération Internationale de Gynécologie et d’Obstétrique (FIGO) stadium I versus FIGO stadium II–IV cases. High expression of EP3 (IRS ≥ 1.5) in cervical cancer patients was correlated with poor prognosis in overall survival rates. Survival in adenocarcinoma (AC) of the cervix was lower than in squamous cell carcinoma (SCC). Cox regression analysis shows that EP3 is an independent prognosticator. In this study we could show that the membrane-bound prostaglandin receptor EP3 is an independent prognosticator for cervical cancer patient survival. Targeting the EP3 receptor seems to be an interesting candidate for endocrine therapy. Therefore, more research is needed on the influence of the receptor system and its influence on cervical cancer growth.

Synergistic Suppression of Tumor Angiogenesis by the Co-delivering of Vascular Endothelial Growth Factor Targeted siRNA and Candesartan Mediated by Functionalized Carbon Nanovectors.

Single-walled carbon nanotubes (SWNTs) with unique physicochemical properties have exhibited promising biomedical applications as drug and gene carriers. In this study, polyethylenimine (PEI)-modified SWNT conjugates linked with candesartan (CD) were developed to deliver vascular endothelial growth factor (VEGF)-targeted siRNA (siVEGF) for the synergistic and targeted treatment of tumor angiogenesis. The characterization results revealed that SWNT-PEI-CD conjugates were successfully synthesized and exhibited desirable dispersibility and superior stability. Confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) results showed that SWNT-PEI-CD/siVEGF complexes could achieve high cellular uptake and specific intracellular distribution of siRNA in AT1R overexpressed PANC-1 cells. Strong down-regulation of VEGF was also verified by qualitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot in complex-treated PANC-1 cells. The in vitro angiogenesis assay showed that SWNT-PEI-CD/siVEGF complexes highly inhibited tube formation of human umbilical vein endothelial cells. Furthermore, in vivo observation in PANC-1 xenografted nude mice demonstrated that SWNT-PEI-CD/siVEGF complexes exhibited significant distribution at tumor sites and caused obvious inhibition of tumor growth and tumor-associated angiogenesis repression induced by the drug combination of CD and siVEGF. Finally, a WST-1 assay indicated that SWNT-PEI-CD possessed low cytotoxicity, and a hemolysis test showed good biocompatibility of SWNT-PEI-CD. Hematological and histological analyses confirmed that SWNT-PEI-CD/siVEGF complexes did not cause any obvious toxic effects to blood and major organs. These findings suggested that the SWNT-PEI-CD/siVEGF co-delivery system with tumor-targeting specificity, improved endosomal escaping properties, and collaboration of angiogenesis inhibition could be a prospective method for efficient tumor antiangiogenic therapy.

Abstract 2066: Delivery of 2`F-PS2 PTGER3 siRNA-DOPC enhances anti-tumoral activity in cisplatin resistant ovarian cancer model

Abstract RNAi-based therapeutics approaches holds a big promise for clinical translation. However, siRNAs are very weak and highly susceptible to degradation by nucleases. Nanoparticle delivery systems and chemical modifications of small interfering RNA (siRNA) can enhance efficient intracellular delivery and resistance to degradation for various siRNAs resulting in an increase in their clinical therapeutic potential. Here, we hypothesized that DOPC nanoparticles incorporated with a chemically fluoro phosphorodithioate (2`F-PS2) modified-PTGER3 siRNA will enhance the stability, prolong the silencing effect in vitro and increase the anti-tumoral effect when is combined with cisplatin in vivo. We screened 51 different chemically modified PTGER3-siRNAs which have 2'-F-PS2 or 2'-O-methyl modification on selectively protected nuclease-sensitive sites. We determined PTGER3 gene expression after siRNA-2'-F-PS2 or 2'-O-methyl modified mediated silencing, stability, time-response silencing effect and the therapeutic effect in xenograft OC in vivo model. We demonstrated that siRNA-2'-F-PS2 prolong the stability for more than 24 hours and enhance the silencing for more than 96 hours. Moreover, we found that PTGER3-silencing effect can control the expression of CFTR multidrug resistant pump by regulating ERK-ELK1-ETS1-CFTR axis, resulting in an increase of the cisplatin uptake, decreased the tumor-associated angiogenesis and tumor growth in xenograft OC in vivo model. SiRNA-PTGER3-2'-F-PS2 modification increase the stability and time-response silencing effect, leading to a synergistic anti-tumor in combination with cisplatin in ovarian cancer models. Citation Format: Emine Bayraktar, Cristian Rodriguez-Aguayo, Zahid Siddik, Gabriel Lopez-Berestein. Delivery of 2`F-PS2 PTGER3 siRNA-DOPC enhances anti-tumoral activity in cisplatin resistant ovarian cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2066. doi:10.1158/1538-7445.AM2017-2066

Intravitreal itraconazole inhibits laser-induced choroidal neovascularization in rats.

Choroidal neovascularization (CNV) is a major cause of severe visual loss in patients with age-related macular degeneration (AMD). Recently, itraconazole has shown potent and dose-dependent inhibition of tumor-associated angiogenesis. We evaluated the anti-angiogenic effect of itraconazole in a rat model of laser-induced CNV. After laser photocoagulation in each eye to cause CNV, right eyes were administered intravitreal injections of itraconazole; left eyes received balanced salt solution (BSS) as controls. On day 14 after laser induction, fluorescein angiography (FA) was used to assess abnormal vascular leakage. Flattened retinal pigment epithelium (RPE)-choroid tissue complex was stained with Alexa Fluor 594-conjugated isolectin B4 to measure the CNV area and volume. Vascular endothelial growth factor receptor 2 (VEGFR2) mRNA and protein expression was determined 1, 4, 7, and 14 days after intravitreal injection by quantitative RT-PCR or Western blot. VEGF levels were analyzed by enzyme-linked immunosorbent assay (ELISA). Intravitreal itraconazole significantly reduced leakage from CNV as assessed by FA and CNV area and volume on flat mounts compared with intravitreal BSS (p = 0.002 for CNV leakage, p<0.001 for CNV area and volume). Quantitative RT-PCR showed significantly lower expression of VEGFR2 mRNA in the RPE-choroid complexes of itraconazole-injected eyes than those of BSS-injected eyes on days 7 and 14 (p = 0.003 and p = 0.006). Western blots indicated that VEGFR2 was downregulated after itraconazole treatment. ELISA showed a significant difference in VEGF level between itraconazole-injected and BSS-injected eyes on days 7 and 14 (p = 0.04 and p = 0.001). Our study demonstrated that intravitreal itraconazole significantly inhibited the development of laser-induced CNV in rats. Itraconazole had anti-angiogenic activity along with the reduction of VEGFR2 and VEGF levels. Itraconazole may prove beneficial for treating CNV as an alternative or adjunct to other therapies.

MicroRNA-7 suppresses the homing and migration potential of human endothelial cells to highly metastatic human breast cancer cells

Background:MicroRNA-7 (miR-7) has been observed as a potent tumour suppressor in multiple cancer types including breast cancer. The aim of this study was to investigate the response sensitivities of metastatic breast cancer cells to miR-7 and the roles of miR-7 in the interaction of endothelial cells and metastatic cancer cells.Methods:Expression profile of miRNAs in a breast cancer specimen cohort and breast cancer cells were determined using real-time quantitative miRNA assays. Effect of the altering expression of miR-7 on migration, invasion, proliferation, interaction and underlying molecular mechanism of breast cancer cells and endothelial cells was investigated after treatment with the synthesised mimic of miR-7. Luciferase activity analysis was performed to validate Wave-3 as a novel target of miR-7.Results:miR-7 expression was negatively correlated with the stage, grade and survival of the breast cancer patients. There was also differential expression of miRNAs including miR-7 in the breast cancer cells. The synthesised mimic of miR-7 inhibits the motility and wound healing potential of breast cancer cells. The highly metastatic MDA-MB-231 cells are more sensitive to the miR-7 treatment than the poorly invasive MCF-7 cells. Treatment with miR-7 downregulated the expression of EGFR, IGF1R and Wave3 in MDA-MB-231 cells but not in MCF-7 cells. In addition, we further demonstrated that miR-7 inhibited the proliferation, migration and invasion of endothelial cells. And more importantly, miR-7 suppressed the homing and migration of endothelial cells to more aggressive tumour cell conditions.Conclusions:Given the dual inhibitory effect of miR-7 on metastatic breast cancer cells alone and the interaction of endothelial cells with the tumour-conditioned microenvironment, we suggest miR-7 may be a new therapeutic candidate for its capacity not only to prevent breast cancer cell spreading but also to inhibit tumour-associated angiogenesis in the metastatic breast cancer.

The angiostatic molecule Multimerin 2 is processed by MMP-9 to allow sprouting angiogenesis

Angiogenesis is a crucial process occurring under physiological and pathological conditions, including cancer. The development of blood vessels is tightly regulated by a plethora of cytokines, endothelial cell (EC) receptors and extracellular matrix (ECM) components. In this context, we have shown that Multimerin 2 (MMRN2), an ECM molecule specifically secreted by ECs, exerts angiostatic functions by binding VEGFA and other pro-angiogenic cytokines. Here, we demonstrate that during angiogenic stimuli MMRN2 mRNA levels significantly decrease. Furthermore, we provide evidence that MMRN2 is processed by matrix metalloproteinases (MMPs) including MMP-9 and, to a lesser degree, by MMP-2. This proteolytic cleavage correlates with an increased migration of ECs. Accordingly, MMRN2 down-regulation is associated with an increased number of EC pseudopodia at the migrating front and this effect is attenuated using specific MMP-9 inhibitors. The down-modulation of MMRN2 occurs also in the context of tumor-associated angiogenesis. Immunofluorescence performed on tumor sections indicate a broad co-localization of MMP-9 and MMRN2, suggesting that the molecule may be extensively remodeled during tumor angiogenesis. Given the altered expression in tumors and the key role of MMRN2 in blood vessel function, we postulate that analyses of its expression may serve as a marker to predict the efficacy of the treatments. In conclusion, these data further support the role of MMRN2 as a key molecule regulating EC function and sprouting angiogenesis.

Association of Macrophages With Angiogenesis in Oral Epithelial Dysplasia, Oral Verrucous Carcinoma, and Oral Squamous Cell Carcinoma: An Immunohistochemical Study.

The present study aimed to elucidate the role of tumor-associated macrophages (TAMs) and angiogenesis in tumor progression by assessing their immunohistochemical expression in oral epithelial dysplasia (OED), oral verrucous carcinoma (OVC), and oral squamous cell carcinoma (OSCC). About 20 histopathologically confirmed cases of OED, OVC, and OSCC each and 10 cases of normal oral mucosa taken as controls were stained immunohistochemically using CD68 and CD31 antibodies. The average TAM count and the microvessel density (MVD) were calculated for each group and expressed as mean±SD and compared using the Mann-Whitney U Test. Pearson correlation was applied to assess the correlation between TAM and MVD in different groups. The CD68 count was found to be significantly higher in all the groups as compared with controls, with the highest counts in OSCC, followed by OED and OVC. MVD was significantly higher in all the test groups as compared with controls. The increase in MVD was highly significant in OSCC as compared with OVC, and in OVC as compared with OED. No association could be determined between TAM and MVD. There does not seem to be any direct influence of macrophages on angiogenesis in the microenvironment of OED, OVC, and OSCC.

Dual roles of protein tyrosine phosphatase kappa in coordinating angiogenesis induced by pro-angiogenic factors.

A potential role may be played by receptor-type protein tyrosine phosphatase kappa (PTPRK) in angiogenesis due to its critical function in coordinating intracellular signal transduction from various receptors reliant on tyrosine phosphorylation. In the present study, we investigated the involvement of PTPRK in the cellular functions of vascular endothelial cells (HECV) and its role in angiogenesis using in vitro assays and a PTPRK knockdown vascular endothelial cell model. PTPRK knockdown in HECV cells (HECVPTPRKkd) resulted in a decrease of cell proliferation and cell-matrix adhesion; however, increased cell spreading and motility were seen. Reduced focal adhesion kinase (FAK) and paxillin protein levels were seen in the PTPRK knockdown cells which may contribute to the inhibitory effect on adhesion. HECVPTPRKkd cells were more responsive to the treatment of fibroblast growth factor (FGF) in their migration compared with the untreated control and cells treated with VEGF. Moreover, elevated c-Src and Akt1 were seen in the PTPRK knockdown cells. The FGF-promoted cell migration was remarkably suppressed by an addition of PLCγ inhibitor compared with other small inhibitors. Knockdown of PTPRK suppressed the ability of HECV cells to form tubules and also impaired the tubule formation that was induced by FGF and conditioned medium of cancer cells. Taken together, it suggests that PTPRK plays dual roles in coordinating angiogenesis. It plays a positive role in cell proliferation, adhesion and tubule formation, but suppresses cell migration, in particular, the FGF-promoted migration. PTPRK bears potential to be targeted for the prevention of tumour associated angiogenesis.

The Polyclonal Antibodies Induced by VBP3 Complex Peptide Targeting Angiogenesis and Tumor Suppression

Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) play a critical role in tumor-associated angiogenesis and have become the targets of anti-tumor therapy. The BALB/c mice were immunized with VEGF/bFGF complex peptide (VBP3) constructed with different epitope peptides of human VEGF and bFGF. The results of the immunogenicity showed that the VBP3 could effectively stimulate immune response in mice and elicit the mice to produce high titer specific anti-VEGF and anti-bFGF antibodies (anti-VBP3 antibodies). The polyclonal anti-VBP3 antibodies separated from the mouse immune serum could effectively inhibit the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) and block the proliferation and migration of lung cancer A549 cells. Besides, the anti-VBP3 antibodies could effectively inhibit tumor growth and tumor angiogenesis in BABL/c nude mice. The results demonstrated that the VBP3 complex peptide could elicit the body to produce the high titer anti-VEGF and anti-bFGF antibodies, which showed anti-tumor and anti-angiogenic effects in vitro and in vivo. The results revealed that the VBP3 complex peptide could be used as a potential peptide vaccine in tumor therapy.

Epimedin C Promotes Vascularization during BMP2-Induced Osteogenesis and Tumor-Associated Angiogenesis.

Epimedin C is one of the chemical markers and major flavonoids in Herba Epimedii (Yinyanghuo), which is traditionally used to treat bone diseases and gonadal dysfunction in China. Our previous study indicated that epimedin C could induce endothelial-like, but not osteogenic differentiation of C3H/10T1/2 cells in vitro. As vasculogenesis plays a pivotal role in bone formation, this study used the bone morphogenetic protein 2 (BMP2) induced ectopic bone formation model and mice 4T1 breast cancer cells co-implanted with luciferase labeled C3H/10T1/2 cells (4T1 [Formula: see text] C3H/10T1/2-Luc) model to examine the in vivo effects of Epimedin C on vasculogenesis. As a result, Epimedin C significantly increased the bone weight and blood perfusion of mice in the BMP2 induced ectopic osteogenesis model, and the bone in Epimedin C [Formula: see text] BMP2 group was more mature than that in BMP2 group. In addition, the tumor weight, blood perfusion and tumor-associated angiogenesis were also significantly increased in the Epimedin C treated 4T1 tumor bearing mice. The mRNA levels of endothelial markers, such as the platelet endothelial adhesive factor-1(CD31), the endothelial cell specific molecule-1(ESM-1), and the vascular von Willebrand factor (vWF) in mouse 4T1 mammary tumor tissue, were commonly found to occur alongside the luciferase (labeled in C3H/10T1/2 cells) expression and significantly increased after Epimedin C treatment. Taken together, Epimedin C can effectively promote vascularization both in the BMP2-depended bone formation model and in the 4T1 mammary tumor-bearing model by inducing an endothelial-like differentiation of C3H/10T1/2 in BALB/c nude mice.