A novel four-step system for screening angiogenesis inhibitors

Antiproliferative Activity of Buddleja saligna (Willd.) against Melanoma and In Vivo Modulation of Angiogenesis

Melanoma cells secrete pro-angiogenic factors, which stimulates growth, proliferation and metastasis, and therefore are key therapeutic targets. Buddleja saligna (BS), and an isolated triterpenoid mixture (DT-BS-01) showed a fifty percent inhibitory concentration (IC₅₀) of 33.80 ± 1.02 and 5.45 ± 0.19 µg/mL, respectively, against melanoma cells (UCT-MEL-1) with selectivity index (SI) values of 1.64 and 5.06 compared to keratinocytes (HaCat). Cyclooxygenase-2 (COX-2) inhibition was observed with IC₅₀ values of 35.06 ± 2.96 (BS) and 26.40 ± 4.19 µg/mL (DT-BS-01). BS (30 µg/mL) significantly inhibited interleukin (IL)-6 (83.26 ± 17.60%) and IL-8 (100 ± 0.2%) production, whereas DT-BS-01 (5 µg/mL) showed 51.07 ± 2.83 (IL-6) and 0 ± 6.7% (IL-8) inhibition. Significant vascular endothelial growth factor (VEGF) inhibition, by 15.84 ± 4.54 and 12.21 ± 3.48%, respectively, was observed. In the ex ovo chick embryo yolk sac membrane assay (YSM), BS (15 µg/egg) significantly reduced new blood vessel formation, with 53.34 ± 11.64% newly formed vessels. Silver and palladium BS nanoparticles displayed noteworthy SI values. This is the first report on the significant anti-angiogenic activity of BS and DT-BS-01 and should be considered for preclinical trials as there are currently no US Food and Drug Administration (FDA) approved drugs to inhibit angiogenesis in melanoma.

Empagliflozin induces apoptotic-signaling pathway in embryonic vasculature: In vivo and in silico approaches via chick’s yolk sac membrane model

The present investigation was conducted to evaluate the vascular-toxicity of empagliflozin (EMP) in embryonic vasculature. Firstly, the vascular-toxicity of the drug as well as its interaction with apoptotic regulator proteins was predicted via in silico approach. In the next step, the apoptotic-signaling pathway in embryonic vasculature was evaluated using a chick’s YSM model. In silico simulation confirmed vascular-toxicity of EMP. There was also an accurate affinity between EMP, Bax and Bcl-2 (−7.9 kcal/mol). Molecular dynamics assay revealed complex stability in the human body conditions. Furthermore, EMP is suggested to alter Bcl-2 more than BAX. Morphometric quantification of the vessels showed that the apoptotic activity of EMP in embryonic vasculature was related to a marked reduction in vessel area, vessel diameter and mean capillary area. Based on the qPCR and immunohistochemistry assays, enhanced expression level of BAX and reduced expression level of Bcl-2 confirmed apoptotic responses in the vessels of the YSM. We observed that induction of an apoptotic signal can cause the embryonic defect of the vascular system following EMP treatment. The acquired data also raised suspicions that alteration in apoptotic genes and proteins in the vasculature are two critical pathways in vascular-toxicity of EMP.

A novel method of screening combinations of angiostatics identifies bevacizumab and temsirolimus as synergistic inhibitors of glioma-induced angiogenesis

Tumor angiogenesis is critical for the growth and progression of cancer. As such, angiostasis is a treatment modality for cancer with potential utility for multiple types of cancer and fewer side effects. However, clinical success of angiostatic monotherapies has been moderate, at best, causing angiostatic treatments to lose their early luster. Previous studies demonstrated compensatory mechanisms that drive tumor vascularization despite the use of angiostatic monotherapies, as well as the potential for combination angiostatic therapies to overcome these compensatory mechanisms. We screened clinically approved angiostatics to identify specific combinations that confer potent inhibition of tumor-induced angiogenesis. We used a novel modification of the ex ovo chick chorioallantoic membrane (CAM) model that combined confocal and automated analyses to quantify tumor angiogenesis induced by glioblastoma tumor onplants. This model is advantageous due to its low cost and moderate throughput capabilities, while maintaining complex in vivo cellular interactions that are difficult to replicate in vitro. After screening multiple combinations, we determined that glioblastoma-induced angiogenesis was significantly reduced using a combination of bevacizumab (Avastin®) and temsirolimus (Torisel®) at doses below those where neither monotherapy demonstrated activity. These preliminary results were verified extensively, with this combination therapy effective even at concentrations further reduced 10-fold with a CI value of 2.42E-5, demonstrating high levels of synergy. Thus, combining bevacizumab and temsirolimus has great potential to increase the efficacy of angiostatic therapy and lower required dosing for improved clinical success and reduced side effects in glioblastoma patients.

Applications of the Chick Chorioallantoic Membrane as an Alternative Model for Cancer Studies

A variety of in vivo experimental models have been established for the studies of human cancer using both cancer cell lines and patient-derived xenografts (PDXs). In order to meet the aspiration of precision medicine, the in vivomurine models have been widely adopted. However, common constraints such as high cost, long duration of experiments, and low engraftment efficiency remained to be resolved. The chick embryo chorioallantoic membrane (CAM) is an alternative model to overcome some of these limitations. Here, we provide an overview of the applications of the chick CAM model in the study of oncology. The CAM model has shown significant retention of tumor heterogeneity alongside increased xenograft take rates in several PDX studies. Various imaging techniques and data analysis have been applied to study tumor metastasis, angiogenesis, and therapeutic response to novel agents. Lastly, to practically illustrate the feasibility of utilizing the CAM model, we summarize the general protocol used in a case study utilizing an ovarian cancer PDX.

R5, a neutralizing antibody to Robo1, suppresses breast cancer growth and metastasis by inhibiting angiogenesis via down-regulating filamin A

Breast cancer (BC) is one of the most common cancers among women in both developed and developing countries with a rising incidence. Using the MMTV-PyMT transgenic mouse model and xenografted breast cancer model, we found that R5, a neutralizing antibody to Robo1, significantly inhibited BC growth and metastasis. Angiogenesis is involved in the growth and metastasis of BC. Interestingly, R5 significantly decreases microvessel density in BC tissues, and inhibits blood vessel formation and development in in vivo chick embryo chorioallantoic membrane (CAM), yolk sac membrane (YSM) and Matrigel plug models. To investigate whether its anti-breast cancer efficacy is ascribed to its direct antiangiogenic properties, xenografted breast cancer model on CAM was established. Furthermore, R5 significantly reduces the tube formation of the vascular plexus on xenografted breast tumor on CAM. R5 also suppresses the migration and the tubular structure formation of human umbilical vein endothelial cells (HUVECs) by down-regulating the expression of filamin A (FLNA). These findings show that R5 has the potential to be a promising agent for the treatment of BC by suppressing the tumor-induced angiogenesis.

Establishment of an in ovo chick embryo yolk sac membrane (YSM) assay for pilot screening of potential angiogenic and anti-angiogenic agents

Angiogenesis, the process of new blood vessel formation from pre-existing vessels, is essential for growth and development. Development of drugs that can accelerate or decelerate angiogenesis in the context of various diseases requires appropriate preclinical screening. As angiogenesis involves complex cellular and molecular processes, in vivo studies are superior to in vitro investigations. Conventional in vitro, in vivo, and ex ovo models of angiogenesis are time consuming and tedious, and require sophisticated infrastructure for embryo culture. In the present study, we established an in ovo chick embryo yolk sac membrane (YSM) assay for angiogenesis and tested the angiogenic potential of arginine, conditioned medium (CM) from human adipose tissue and placenta-derived mesenchymal stem cells (ADMSCs-CM and PDMSCs-CM), avastin and vitamin C. The obtained results were confirmed with the routinely employed chick embryo Chorioallantoic Membrane (CAM) assay. Both assays revealed the pro-angiogenic nature of arginine, ADMSCs-CM, and PDMSCs-CM, and the anti-angiogenic effect of avastin and vitamin C. This novel in ovo YSM model is simple, reproducible, and highly economic in terms of the time frame and cost incurred. The proposed model is thus a suitable substitute to the CAM model for pilot screening of potential angiogenic and anti-angiogenic agents.

Omega-3 polyunsaturated fatty acids promote angiogenesis in placenta derived mesenchymal stromal cells

Enhancement of angiogenesis is solicited in wound repair and regeneration. Mesenchymal stromal cells derived from the placenta (P-MSCs) have an inherent angiogenic potential. Polyunsaturated fatty acids (PUFAs) in turn, specifically the omega-3 (N-3) are essential for growth and development. They are also recommended as dietary supplements during pregnancy. We therefore hypothesized that addition of N-3 PUFAs in P-MSC culture media may enhance their angiogenic potential. Hence, we treated P-MSCs with omega-3 (N-3) fatty acids -Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA) at different concentrations and tested their angiogenic potential. We saw an upregulation of both bFGF and VEGFA. We also found enhanced in vitro tube formation ability of P-MSCs treated with DHA: EPA. We then looked at the influence of the conditioned medium (CM) collected from P-MSCs exposed to DHA: EPA on the key effector cells -HUVECs (Human Umbilical Vein derived endothelial cells and their functionality was further confirmed on chick yolk sac membrane. We found that the CM of P-MSCs exposed to DHA: EPA could enhance angiogenesis in both cases. These result were finally validated in an in vivo matrigel plug assay which revealed enhanced migration and vessel formation in CM treated with DHA: EPA. Our data thus reveals for the first time that supplementation with lower concentration of PUFA enhances the angiogenic potential of P-MSCs making them suitable for chronic wound healing applications.

HMGA1 Overexpression is Associated With the Malignant Status and Progression of Breast Cancer

Breast cancer is the most common malignant tumor among women, and the incidence and mortality of breast cancer has rapidly increased in recent years. Studies have indicated that high mobility group A1 (HMGA1), an important member of the HMGA family, plays a role in the pathogenesis and progression of malignant tumors, including breast cancer. This study aims to evaluate the effect of HMGA1 in breast cancer. Interestingly, we found that HMGA1 expression was significantly higher in breast cancer tissues than in adenoma tissues and closely correlated with the clinical stage and histological grade in breast cancer patients. Further study showed that HMGA1 knockdown inhibited the proliferation and migration of breast cancer cells. Thus, the results demonstrated that HMGA1 could act as an independent prognostic indicator in breast cancer. HMGA1 expression was closely correlated with the clinical stage, histological grade, and tumor size in breast cancer patients and breast cancer progression in transgenic MMTV-PyMT mice. Anat Rec, 301:1061-1067, 2018. © 2018 Wiley Periodicals, Inc.

Use of animal models for the imaging and quantification of angiogenesis

Angiogenesis is the process of developing new blood vessels from the original vascular network; it is necessary for normal physiological processes, such as embryonic development and wound healing. Angiogenesis is also involved in pathological events, including myocardial ischemia and tumor growth. To investigate the molecular mechanisms of this important process, a variety of methods and models are employed. These strategies can also be used to provide insight into the etiology of angiogenesis-related diseases, thereby contributing to the development of new diagnostics and treatments. Commonly used animal models include the chorioallantoic membrane and yolk sac membrane of chick embryos, the mouse retina and aortic ring, and angiogenesis reactors implanted into mice. These animal models have been instrumental in the study of the angiogenic process. For example, the chorioallantoic membrane undergoes robust angiogenesis during the development of chick embryos, and, because its surface is easily accessible, this membrane provides a convenient model for experimentation. Here, we discuss the methods that employ animal models for the imaging and quantification of angiogenesis. In addition, we propose potential novel directions for future investigations in this area.