Zebrafish Model: Worth Considering in Defining Tumor Angiogenesis

Antiangiogenic potential of Lepista nuda extract suppressing MAPK/p38 signaling-mediated developmental angiogenesis in zebrafish and HUVECs

The medicinal properties of natural/edible plant products and their use are popular in traditional practice owing to their nutritional contents with little to no side effects. Lepista nuda (L. nuda), an edible mushroom (Clitocybe nuda, commonly known as blewit), has attracted researchers to evaluate its contents and the mechanism of its activities. In the current study, we focused on evaluating the antiangiogenic effects of L. nuda water extract on zebrafish development and in vitro human umbilical vein endothelial cell (HUVEC) tube formation. Bioactive components such as ergothioneine, eritadenine, and adenosine were identified and quantified by HPLC analysis. The L. nuda extract showed antiangiogenic properties and inhibited intersegmental vessel (ISV), caudal vein plexus (CVP), hyaloid vessel (HV), and subintestinal vessel (SIV) development in Tg (fli1: EGFP) zebrafish embryos. The expression of angiogenesis-related genes (vegfaa, kdrl, vegfba, flt1, kdr) was affected following L. nuda extract treatment. L. nuda extract attenuated in vitro HUVEC tube formation, migration, and invasion. Furthermore, inhibition of MAPK/p38 signaling and depletion of proangiogenic genes, including growth factors (fgf, ang2, and vegfa); primary and accessory receptors (tie2, vegfr2, and eng); MMPs (mmp1 and mmp2); and cytokines (il-1α, il-1β, il-6, and tnf-α) was observed in HUVECs following L. nuda treatment. An in vivo zebrafish xenograft assay showed that L. nuda extract inhibited HuCCT1 cell-induced SIV sprouting in HuCCT1-injected embryos. Collectively, the results suggest that L. nuda could be a potential inhibitor of angiogenesis limiting cancer progression.

Oxidative Stress and AKT-Associated Angiogenesis in a Zebrafish Model and Its Potential Application for Withanolides

Oxidative stress and the AKT serine/threonine kinase (AKT) signaling pathway are essential regulators in cellular migration, metastasis, and angiogenesis. More than 300 withanolides were discovered from the plant family Solanaceae, exhibiting diverse functions. Notably, the relationship between oxidative stress, AKT signaling, and angiogenesis in withanolide treatments lacks comprehensive understanding. Here, we summarize connecting evidence related to oxidative stress, AKT signaling, and angiogenesis in the zebrafish model. A convenient vertebrate model monitored the in vivo effects of developmental and tumor xenograft angiogenesis using zebrafish embryos. The oxidative stress and AKT-signaling-modulating abilities of withanolides were highlighted in cancer treatments, which indicated that further assessments of their angiogenesis-modulating potential are necessary in the future. Moreover, targeting AKT for inhibiting AKT and its AKT signaling shows the potential for anti-migration and anti-angiogenesis purposes for future application to withanolides. This particularly holds for investigating the anti-angiogenetic effects mediated by the oxidative stress and AKT signaling pathways in withanolide-based cancer therapy in the future.

Zebrafish Xenograft Model to Study Human Cancer

The zebrafish, Danio rerio, has been an important animal model for cancer research over the last decade. The capability of a high-throughput screen in zebrafish and a wide range of pharmacologically active compounds elicit physiological responses in zebrafish embryos comparable to those in mammalian systems, making zebrafish ideal for identifying clinically relevant drug targets and compounds that regulate tumor progression. The zebrafish model is suitable for patient-derived xenograft (pdx) and large-scale screening of lead compounds against specific malignancies. This established vertebrate model has many advantages, including fast response time, cost efficiency for drug testing, efficient manipulation of the host microenvironment by genetic tools, suitable for small molecule drug screening in high-throughput setting, easy maintenance, transparency for easy observation, high fecundity, and rapid generation time. The zebrafish model is a good alternative in vivo model to mammals for robust testing of drug candidates for cancer therapy.

Anti-angiogenesis and anti-metastasis effects of Polyphyllin VII on Hepatocellular carcinoma cells in vitro and in vivo

Background

Polyphyllin VII (PP7), a steroidal saponin from P. polyphylla has been found to exert strong anticancer activity. Little is known about the anti-angiogenesis and anti-metastasis properties of PP7. In this study, the anti-angiogenic and anti-metastatic effects of PP7 on HCC and the molecular mechanisms were evaluated.

Methods

Effect of PP7 on angiogenesis was assessed by tube formation assay and applied a transgenic Tg(fli1:EGFP) zebrafish model. Effects of PP7 on tumor metastasis and invasion were examined in cell migration and invasion assay, zebrafish tumor xenograft models and lung metastasis mouse models. The protein levels were examined by Western blotting.

Results

PP7 significantly decreased the tube formation of human umbilical vein endothelial cells, the number and length of ISVs and SIVs of transgenic zebrafish, and the metastasis and invasion of cancer cells in vitro and in vivo. The anti-angiogenic and anti-metastatic effects of PP7 in HepG2 cells were attributable, at least partially, to downregulated NF-κB/MMP-9/VEGF signaling pathway.

Conclusion

This study demonstrates that PP7 possesses strong anti-angiogenesis and anti-metastasis activities, suggesting that PP7 could be a potential candidate agent for HCC treatment.

Inhibitory Effects of Euphorbia ebracteolata Hayata Extract ECB on Melanoma-Induced Hyperplasia of Blood Vessels in Zebrafish Embryos

Melanoma is a serious malignant form of skin cancer. Euphorbiaceae compound B (ECB, 2,4-dihydroxy-6-methoxy-3-methylacetophenone) is an acetophenone compound that is isolated from Euphorbia ebracteolata Hayata (EEH), an herbaceous perennial, and has antitumor activity. Here, we transplanted human melanoma cells into zebrafish embryos to establish a zebrafish/melanoma model. We showed that this model can be used to evaluate the therapeutic effect of EEH and ECB and discussed its potential mechanism of action. The results showed that ECB was an active ingredient of EEH in inhibiting melanoma-induced hyperplasia of blood vessels in zebrafish embryos, similar to the angiogenic inhibitor vatalanib. ECB inhibited the number and length of subintestinal veins (p < 0.05), as well as the distribution of melanoma in zebrafish embryos (p < 0.05). More importantly, unlike vatalanib, ECB only inhibited melanoma-induced abnormal and excessive growth of blood vessels in xenografts. In addition, ECB inhibited the mRNA expression of vegfr2 and vegfr3 in zebrafish. Both vegfr2 and vegfr3 are essential genes that regulate blood vessel formation and upregulate the expression of p53 and casp3a genes in zebrafish. Together, the above-mentioned results indicate that ECB has a potential antimelanoma effect in vivo, which may be mediated by inhibiting vascular endothelial growth factor receptors.

Targeted therapy of human leukemia xenografts in immunodeficient zebrafish

Personalized medicine holds tremendous promise for improving safety and efficacy of drug therapies by optimizing treatment regimens. Rapidly developed patient-derived xenografts (pdx) could be a helpful tool for analyzing the effect of drugs against an individual's tumor by growing the tumor in an immunodeficient animal. Severe combined immunodeficiency (SCID) mice enable efficient in vivo expansion of vital tumor cells and generation of personalized xenografts. However, they are not amenable to large-scale rapid screening, which is critical in identifying new compounds from large compound libraries. The development of a zebrafish model suitable for pdx could facilitate large-scale screening of drugs targeted against specific malignancies. Here, we describe a novel strategy for establishing a zebrafish model for drug testing in leukemia xenografts. We used chronic myelogenous leukemia and acute myeloid leukemia for xenotransplantation into SCID zebrafish to evaluate drug screening protocols. We showed the in vivo efficacy of the ABL inhibitor imatinib, MEK inhibitor U0126, cytarabine, azacitidine and arsenic trioxide. We performed corresponding in vitro studies, demonstrating that combination of MEK- and FLT3-inhibitors exhibit an enhanced effect in vitro. We further evaluated the feasibility of zebrafish for transplantation of primary human hematopoietic cells that can survive at 15 day-post-fertilization. Our results provide critical insights to guide development of high-throughput platforms for evaluating leukemia.

Characterization of prostate cancer cell progression in zebrafish xenograft model

Early diagnosis of prostate cancer (PCa) is critical for the application of efficient treatment to PCa patients. However, the majority of PCas remains indolent from several months to several years before malignancy. Current diagnosis methods have limitations in their reliability and are inefficient in time cost. Thus, an efficient in vivo PCa cell xenograft model is highly desired for diagnostic studies in PCas. In the present study we present a standardized procedure to create a PCa cell xenograft model using zebrafish (Danio rerio) as the host. PC3-CTR cells, a cell line from adenocarcinoma with stable expression of calcitonin receptor (CRT), were subcutaneously injected into zebrafish larvae at 48 h post fertilization. The nursing conditions for the larvae were optimized with stable survival rates of post hatch and post PC3-CTR cell injection. In this system, the progression of PC3-CTR cells in vivo was evaluated by migration and proliferation of the cells. Massive migrations of PC3 cells in vivo were observed at post injection day (PID)3. The injected PC3-CTR cells eventually invaded the whole larval zebrafish at PID5. Quantification of PC3-CTR cell proliferation was done using quantitative PCR (qPCR) analysis targeting the expression profiles of two PCa housekeeping genes, TATA-binding protein (TBP) and hypoxanthine phosphoribosyltransferase 1 (HPRT1) encoding genes. The excessive proliferation of PC3 cells in vivo was detected with both qPCR assays. Expression levels of one non-coding gene, prostate cancer associated 3 gene (pca3), and two other genes encoding transient receptor potential ion channel Melastatin 8 (trpm8) and prostate-specific membrane antigen (psma), showed a significantly enhanced aggressiveness of PC3-CTR cells in vivo. The model established in the present study provides an improved in vivo model for the diagnosis of PCas efficiently. This PCa cell xenograft model can also serve as a tool for high throughput anti-PCa drug screening in therapeutic treatments.

Nanodiamond for biolabelling and toxicity evaluation in the zebrafish embryo in vivo

Nanodiamond (ND) has been proposed for various biomedical applications, including bioimaging, biosensing and drug delivery, owing to its physical-chemical properties and biocompatibility. Particularly, ND has been demonstrated as fluorescence- and Raman-detectable labels in many cellular models. Different surface functionalization methods have been developed, varying the ND's surface properties and rendering the possibility to attach biomolecules to provide interaction with biological targets. For this, toxicity is of major concern in animal models. Aside from cellular models, a cost-effective animal test will greatly facilitate the development of applications. In this study, we use the rapid, sensitive and reproducible zebrafish embryo model for in vivo nanotoxicity test. We optimize the conditions for using this animal model and analyze the zebrafish embryonic development in the presence of ND. ND is observed in the embryo in vivo using laser confocal fluorescence microscopy and fluorescence lifetime imaging. Using the zebrafish model for a safety evaluation of ND-based nanolabel is discussed.

Zebrafish xenotransplantation as a tool for in vivo cancer study

Zebrafish represents a powerful model for cancer research. Particularly, the xenotransplantation of human cancer cells into zebrafish has enormous potential for further evaluation of cancer progression and drug discovery. Various cancer models have been established in adults, juveniles and embryos of zebrafish. This xenotransplantation zebrafish model provides a unique opportunity to monitor cancer proliferation, tumor angiogenesis, metastasis, self-renewal of cancer stem cells, and drug response in real time in vivo. This review summarizes the use of zebrafish as a model for cancer xenotransplantation, and highlights its advantages and disadvantages.

A novel association of neuropilin-1 and MUC1 in pancreatic ductal adenocarcinoma: role in induction of VEGF signaling and angiogenesis

We report that MUC1, a transmembrane glycoprotein that is overexpressed in >80% of pancreatic ductal adenocarcinoma (PDA) induced a pro-angiogenic tumor microenvironment by increasing the levels of neuropilin-1 (NRP1, a co-receptor of VEGF) and its ligand, VEGF. Expression of tumor-associated MUC1 (tMUC1) positively correlated with NRP1 levels in human and mouse PDA. Further, tMUC1^hi PDA cells secreted high levels of VEGF and expressed high levels of VEGF receptor 2 and its phosphorylated forms as compared to tMUC1^low/null PDA. This enabled the tMUC1^hi/NRP1^hi PDA cells to a) induce endothelial cell tube formation, b) generate long ectopic blood vessels and c) enhance distant metastasis in a zebrafish xenograft model. Concurrently, the proteins associated with epithelial to mesenchymal transition, N-cadherin and Vimentin, were highly induced in these tMUC1/NRP1^hi PDA cells. Hence, blocking signaling via the NRP1-VEGF axis significantly reduced tube formation, new vessel generation, and metastasis induced by tMUC1^hi PDA cells. Finally, we show that blocking the interaction between VEGF₁₆₅ and NRP1 with a NRP1 antagonist significantly reduced VEGFR signaling and PDA tumor growth in vivo. Taken together, our data suggests a novel molecular mechanism by which tMUC1 may modulate NRP1-dependent VEGFR signaling in PDA cells.

A zebrafish in vivo phenotypic assay to identify 3-aminothiophene-2-carboxylic acid-based angiogenesis inhibitors

Abstract Small molecules that inhibit angiogenesis are attractive drug candidates for cancer, retinopathies, and age-related macular degeneration. In vivo, phenotypic screening in zebrafish (Danio rerio) emerges as a powerful methodology to identify and optimize novel compounds with pharmacological activity. Zebrafish provides several advantages for in vivo phenotypic screens especially for angiogenesis, since it develops rapidly, externally, and does not rely on a functional cardiovascular system to survive for several days during development. In this study, we utilize a transgenic line that allows the noninvasive monitoring of angiogenesis at a cellular level. The inhibition of angiogenesis can be observed under a fluorescent stereoscope and quantified. To exemplify the versatility and robustness of the zebrafish screen, we have employed a series of 60 novel compounds that were designed based on a potent VEGFR2 inhibitor. Herein, we report their structure-based design, synthesis, and in vivo zebrafish screening for optimal activity, toxicity, and off-target effects, which revealed six reversible inhibitors of angiogenesis.

Sp1-driven up-regulation of miR-19a decreases RHOB and promotes pancreatic cancer

Cancer treatment alters microRNA (miRNA) expression, revealing potential therapeutic targets (oncotarget). Here we treated pancreatic cancer (ASPC-1) cells with either recombinant human endostatin (rh-endostatin) or gemcitabine. Then high-throughput sequencing assay was performed to screen for altered miRNAs. Both treatments decreased levels of MiR-19a. We found that miR-19a stimulated cell proliferation, migration, invasion in vitro and tumor growth in vivo. High levels of miR-19a correlated with poor prognosis in patients. Ras homolog family member B (RHOB) was identified as a direct target of miR-19a. Furthermore, RHOB was down-regulated in human pancreatic cancer samples. Restoration of RHOB induced apoptosis, inhibited proliferation and migration of ASPC-1 cells. SP-1 was identified as an upstream transcription factor of miR-19a gene, promoting miR-19a transcription. Rh-endostatin decreased miR-19a expression by down-regulating SP-1. These findings suggest that miR-19a is a potential therapeutic target in pancreatic cancer.

Generation of Viable Plant-Vertebrate Chimeras

The extreme dependence on external oxygen supply observed in animals causes major clinical problems and several diseases are related to low oxygen tension in tissues. The vast majority of the animals do not produce oxygen but a few exceptions have shown that photosynthetic capacity is physiologically compatible with animal life. Such symbiotic photosynthetic relationships are restricted to a few aquatic invertebrates. In this work we aimed to explore if we could create a chimerical organism by incorporating photosynthetic eukaryotic cells into a vertebrate animal model. Here, the microalgae Chlamydomonas reinhardtii was injected into zebrafish eggs and the interaction and viability of both organisms were studied. Results show that microalgae were distributed into different tissues, forming a fish-alga chimera organism for a prolonged period of time. In addition, microscopic observation of injected algae, in vivo expression of their mRNA and re-growth of the algae ex vivo suggests that they survived to the developmental process, living for several days after injection. Moreover microalgae did not trigger a significant inflammatory response in the fish. This work provides additional evidence to support the possibility that photosynthetic vertebrates can be engineered.

Photosynthetic biomaterials: a pathway towards autotrophic tissue engineering

Engineered tissues are highly limited by poor vascularization in vivo, leading to hypoxia. In order to overcome this challenge, we propose the use of photosynthetic biomaterials to provide oxygen. Since photosynthesis is the original source of oxygen for living organisms, we suggest that this could be a novel approach to provide a constant source of oxygen supply independently of blood perfusion. In this study we demonstrate that bioartificial scaffolds can be loaded with a solution containing the photosynthetic microalgae Chlamydomonas reinhardtii, showing high biocompatibility and photosynthetic activity in vitro. Furthermore, when photosynthetic biomaterials were engrafted in a mouse full skin defect, we observed that the presence of the microalgae did not trigger a native immune response in the host. Moreover, the analyses showed that the algae survived for at least 5 days in vivo, generating chimeric tissues comprised of algae and murine cells. The results of this study represent a crucial step towards the establishment of autotrophic tissue engineering approaches and suggest the use of photosynthetic cells to treat a broad spectrum of hypoxic conditions.

Antiangiogenic cancer drug using the zebrafish model

The process of de novo vessel formation, called angiogenesis, is essential for tumor progression and spreading. Targeting of molecular pathways involved in such tumor angiogenetic processes by using specific drugs or inhibitors is important for developing new anticancer therapies. Drug discovery remains to be the main focus for biomedical research and represents the essence of antiangiogenesis cancer research. To pursue these molecular and pharmacological goals, researchers need to use animal models that facilitate the elucidation of tumor angiogenesis mechanisms and the testing of antiangiogenic therapies. The past few years have seen the zebrafish system emerge as a valid model organism to study developmental angiogenesis and, more recently, as an alternative vertebrate model for cancer research. In this review, we will discuss why the zebrafish model system has the advantage of being a vertebrate model equipped with easy and powerful transgenesis as well as imaging tools to investigate not only physiological angiogenesis but also tumor angiogenesis. We will also highlight the potential of zebrafish for identifying antitumor angiogenesis drugs to block tumor development and progression. We foresee the zebrafish model as an important system that can possibly complement well-established mouse models in cancer research to generate novel insights into the molecular mechanism of the tumor angiogenesis.

Zebrafish xenografts as a tool for in vivo studies on human cancer

The zebrafish has become a powerful vertebrate model for genetic studies of embryonic development and organogenesis and increasingly for studies in cancer biology. Zebrafish facilitate the performance of reverse and forward genetic approaches, including mutagenesis and small molecule screens. Moreover, several studies report the feasibility of xenotransplanting human cells into zebrafish embryos and adult fish. This model provides a unique opportunity to monitor tumor-induced angiogenesis, invasiveness, and response to a range of treatments in vivo and in real time. Despite the high conservation of gene function between fish and humans, concern remains that potential differences in zebrafish tissue niches and/or missing microenvironmental cues could limit the relevance and translational utility of data obtained from zebrafish human cancer cell xenograft models. Here, we summarize current data on xenotransplantation of human cells into zebrafish, highlighting the advantages and limitations of this model in comparison to classical murine models of xenotransplantation.

A novel zebrafish human tumor xenograft model validated for anti-cancer drug screening

The development of a relatively simple, reliant and cost-effective animal test will greatly facilitate drug development. In this study, our goal was the establishment of a rapid, simple, sensitive and reproducible zebrafish xenograft model for anti-cancer drug screening. We optimized the conditions for the cancer cell xenograft in terms of injected cell numbers, incubation temperature and time. A range of human carcinoma cell types were stained with a fluorescent dye prior to injection into the fish larvae. Subsequent cancer cell dissemination was observed under fluorescent microscopy. Differences in injected cell numbers were reflected in the rate of dissemination from the xenograft site. Paclitaxel, known as a microtubule stabilizer, dose-dependently inhibited cancer cell dissemination in our zebrafish xenograft model. An anti-migratory drug, LY294002 (phosphatidylinositol 3-kinase inhibitor) also decreased the cancer cell dissemination. Chemical modifications to increase cancer drug pharmacokinetics, such as increased solubility (17-DMAG compared to geldanamycin) could also be assessed in our xenograft model. In addition to testing our new model using known anti-cancer drugs, we carried out further validation by screening a tagged triazine library. Two novel anti-cancer drug candidates were discovered. Therefore, our zebrafish xenograft model provides a vertebrate animal system for the rapid screening and pre-clinical testing of novel anti-cancer agents, prior to the requirement for testing in mammals. Our model system should greatly facilitate drug development for cancer therapy because of its speed, simplicity and reproducibility.

Discriminating different cancer cells using a zebrafish in vivo assay

Despite the expanded understanding of tumor angiogenesis phenomenon and how it impacts cancer treatment outcomes, we have yet to develop a robust assay that can quickly, easily, and quantitatively measure tumor-induced angiogenesis. Since the zebrafish/tumor xenograft represents an emerging tool in this regard, the present study strives to capitalize on the ease, effectiveness, and the adaptability of this model to quantify tumor angiogenesis. In order to test a range of responses, we chose two different tumorigenic cell lines, the human non-small cell lung carcinoma (H1299) and the mouse lung adenocarcinoma (CL13). Non-tumorigenic 3T3-L1 cells served as negative control. The cells were grafted near to the perivitelline space of the zebrafish embryos and the angiogenic response was analyzed using whole-mount alkaline phosphatase (AP) vessel staining and fluorescence microscopy. Angiogenic activity was scored based on the length and number of the newly formed ectopic vessels and the percentage of embryos with ectopic vessels. At 2 day-post-implantation, we detected a significant increase in the length and number of ectopic vessels with H1299 cell implantation compared to CL13 cell transplantation, both are higher than 3T3-L1 control. We also observed a significantly higher percentage of embryos with ectopic vessels with H1299 and CL13 transplantation compared to the 3T3-L1 control, but this parameter is not as robust and reliable as measuring the length and number of ectopic vessels. Furthermore, the systemic exposure of zebrafish embryos to an anti-angiogenesis drug (PTK 787, inhibitor of vascular endothelial growth factor receptor tyrosine kinase) inhibited tumor-induced angiogenesis, suggesting that the assay can be used to evaluate anti-angiogenic drugs. This study implicates the feasibility of using zebrafish xenotransplantation to perform quantitative measurement of the angiogenic activity of cancer cells which can be further extended to measure cancer cell metastasis. This assay represents not only the useful test for patient diagnosis, but also has the potential for evaluating anti-cancer drugs treatment.