Fishing for cures: The alLURE of using zebrafish to develop precision oncology therapies

PDX models for functional precision oncology and discovery science

Precision oncology relies on detailed molecular analysis of how diverse tumours respond to various therapies, with the aim to optimize treatment outcomes for individual patients. Patient-derived xenograft (PDX) models have been key to preclinical validation of precision oncology approaches, enabling the analysis of each tumour's unique genomic landscape and testing therapies that are predicted to be effective based on specific mutations, gene expression patterns or signalling abnormalities. To extend these standard precision oncology approaches, the field has strived to complement the otherwise static and often descriptive measurements with functional assays, termed functional precision oncology (FPO). By utilizing diverse PDX and PDX-derived models, FPO has gained traction as an effective preclinical and clinical tool to more precisely recapitulate patient biology using in vivo and ex vivo functional assays. Here, we explore advances and limitations of PDX and PDX-derived models for precision oncology and FPO. We also examine the future of PDX models for precision oncology in the age of artificial intelligence. Integrating these two disciplines could be the key to fast, accurate and cost-effective treatment prediction, revolutionizing oncology and providing patients with cancer with the most effective, personalized treatments.

A zebrafish xenotransplant model of anaplastic thyroid cancer to study tumor microenvironment and innate immune cell interactions in vivo

Anaplastic thyroid cancer (ATC) is of the most aggressive thyroid cancer. While ATC is rare, it accounts for a disproportionately high number of thyroid cancer-related deaths. Here, we developed an ATC xenotransplant model in zebrafish larvae, where we can study tumorigenesis and therapeutic response in vivo. Using both mouse (T4888M) and human (C643)-derived fluorescently labeled ATC cell lines, we show these cell lines display different engraftment rates, mass volume, proliferation, cell death, angiogenic potential, and neutrophil and macrophage recruitment and infiltration. Next, using a PIP-FUCCI reporter to track proliferation in vivo, we observed cells in each phase of the cell cycle. Additionally, we performed long-term non-invasive intravital microscopy over 48 h to understand cellular dynamics in the tumor microenvironment at the single-cell level. Lastly, we tested two drug treatments, AZD2014 and a combination therapy of dabrafenib and trametinib, to show our model could be used as an effective screening platform for new therapeutic compounds for ATC. Altogether, we show that zebrafish xenotransplants make a great model to study thyroid carcinogenesis and the tumor microenvironment, while also being a suitable model to test new therapeutics in vivo.

Beyond drug discovery: Exploring the physiological and methodological dimensions of zebrafish in diabetes research

Diabetes mellitus is a chronic disease that is now considered a global epidemic. Chronic diabetes conditions include type 1 and type 2 diabetes, both of which are normally irreversible. As a result of long-term uncontrolled high levels of glucose, diabetes can progress to hyperglycaemic pathologies, such as cardiovascular diseases, retinopathy, nephropathy and neuropathy, among many other complications. The complete mechanism underlying diabetes remains unclear due to its complexity. In this scenario, zebrafish (Danio rerio) have arisen as a versatile and promising animal model due to their good reproducibility, simplicity, and time- and cost-effectiveness. The Zebrafish model allows us to make progress in the investigation and comprehension of the root cause of diabetes, which in turn would aid in the development of pharmacological and surgical approaches for its management. The current review provides valuable reference information on zebrafish models, from the first zebrafish diabetes models using genetic, disease induction and chemical approaches, to the newest ones that further allow for drug screening and testing. This review aims to update our knowledge related to diabetes mellitus by gathering the most authoritative studies on zebrafish as a chemical, dietary and insulin induction, and genetic model for diabetes research.

Mapping the Metabolic Characteristics and Perturbation of Adult Casper Zebrafish by Ambient Mass Spectrometry Imaging

Casper, a type of transparent mutant-line zebrafish, was generated to overcome the opaque trunk of an adult zebrafish for tumor modeling to realize real-time visualization of transplanted cells in vivo. However, the molecular information at the metabolic level has not received much attention. Herein, a spatially resolved metabolomics method based on an airflow-assisted desorption electrospray ionization-mass spectrometry imaging (AFADESI-MSI) system for whole-body zebrafish was used to investigate small molecules and the distribution of adult casper (Mitfaw2/w2, roya9/a9) and the differences from wild-type zebrafish. Finally, the spatial distribution information of more than 1500 endogenous ions was obtained in positive and negative detection modes, and 186 metabolites belonging to a variety of structural categories were identified or annotated. Compared with wild-type samples, 85 variables, including 37 known metabolites, were screened out. In addition, the disordered metabolic pathways caused by the genetic mutation were excavated, involving downregulation of purine metabolism and arachidonic acid metabolism, upregulation of glycerophospholipid metabolism, and biosynthesis of unsaturated fatty acids. All these results were observed in the most intuitive way through MSI. This study revealed important metabolic characteristics of and perturbation in adult casper zebrafish, and provides indispensable fundamental knowledge for tumor research based on it.

Myeloid differentiation factor-2/LY96, a potential predictive biomarker of metastasis and poor outcomes in prostate cancer: clinical implications as a potential therapeutic target

Prostate cancer (CaP) is the most diagnosed cancer in males and the second leading cause of cancer deaths. Patients with localized tumors are generally curable. However, no curative treatment exists for patients with advanced and metastatic disease. Therefore, identifying critical proteins involved in the metastatic process would help to develop new therapeutic options for patients with advanced and aggressive CaP. We provide strong evidence that Myeloid differentiation factor-2 (MD2) plays a critical role in metastasis and CaP progression. Analysis of tumor genomic data showed that amplifications of MD2 and increased expression are associated with poor outcomes in patients. Immunohistochemistry analysis of tumor tissues showed a correlation between the expression of MD2 and cancer progression. The Decipher-genomic test validated the potential of MD2 in predicting metastasis. In vitro studies demonstrated that MD2 confers invasiveness by activating MAPK and NF-kB signaling pathways and inducing epithelial-mesenchymal transition. Furthermore, we show that metastatic cells release MD2 (sMD2). We measured serum-sMD2 in patients and found that the level is correlated to disease extent. We determined the significance of MD2 in metastasis in vivo and as a therapeutic target, showing that the molecular and pharmacological targeting of MD2 significantly inhibited metastasis in murine models. We conclude that MD2 predicts metastatic behavior, and serum-MD2 could be studied as a potential non-invasive biomarker for metastasis, whereas MD2 presence on prostate biopsy predicts adverse disease outcome. We suggest MD2-targeted therapies could be developed as potential treatments for aggressive metastatic disease.

Phytochemicals Showing Antiangiogenic Effect in Pre-clinical Models and their Potential as an Alternative to Existing Therapeutics

Angiogenesis, the formation of new blood vessels from a pre-existing vascular network, is an important hallmark of several pathological conditions, such as tumor growth and metastasis, proliferative retinopathies, including proliferative diabetic retinopathy and retinopathy of prematurity, age-related macular degeneration, rheumatoid arthritis, psoriasis, and endometriosis. Putting a halt to pathology-driven angiogenesis is considered an important therapeutic strategy to slow down or reduce the severity of pathological disorders. Considering the attrition rate of synthetic antiangiogenic compounds from the lab to reaching the market due to severe side effects, several compounds of natural origin are being explored for their antiangiogenic properties. Employing pre-clinical models for the evaluation of novel antiangiogenic compounds is a promising strategy for rapid screening of antiangiogenic compounds. These studies use a spectrum of angiogenic model systems that include HUVEC two-dimensional culture, nude mice, chick chorioallantoic membrane, transgenic zebrafish, and dorsal aorta from rats and chicks, depending upon available resources. The present article emphasizes the antiangiogenic activity of the phytochemicals shown to exhibit antiangiogenic behavior in these well-defined existing angiogenic models and highlights key molecular targets. Different models help to get a quick understanding of the efficacy and therapeutics mechanism of emerging lead molecules. The inherent variability in assays and corresponding different phytochemicals tested in each study prevent their immediate utilization in clinical studies. This review will discuss phytochemicals discovered using suitable preclinical antiangiogenic models, along with a special mention of leads that have entered clinical evaluation.

The application of zebrafish patient-derived xenograft tumor models in the development of antitumor agents

The cost of antitumor drug development is enormous, yet the clinical outcomes are less than satisfactory. Therefore, it is of great importance to develop effective drug screening methods that enable accurate, rapid, and high-throughput discovery of lead compounds in the process of preclinical antitumor drug research. An effective solution is to use the patient-derived xenograft (PDX) tumor animal models, which are applicable for the elucidation of tumor pathogenesis and the preclinical testing of novel antitumor compounds. As a promising screening model organism, zebrafish has been widely applied in the construction of the PDX tumor model and the discovery of antineoplastic agents. Herein, we systematically survey the recent cutting-edge advances in zebrafish PDX models (zPDX) for studies of pathogenesis mechanisms and drug screening. In addition, the techniques used in the construction of zPDX are summarized. The advantages and limitations of the zPDX are also discussed in detail. Finally, the prospects of zPDX in drug discovery, translational medicine, and clinical precision medicine treatment are well presented.

Zebrafish Models of Paediatric Brain Tumours

Paediatric brain cancer is the second most common childhood cancer and is the leading cause of cancer-related deaths in children. Despite significant advancements in the treatment modalities and improvements in the 5-year survival rate, it leaves long-term therapy-associated side effects in paediatric patients. Addressing these impairments demands further understanding of the molecularity and heterogeneity of these brain tumours, which can be demonstrated using different animal models of paediatric brain cancer. Here we review the use of zebrafish as potential in vivo models for paediatric brain tumour modelling, as well as catalogue the currently available zebrafish models used to study paediatric brain cancer pathophysiology, and discuss key findings, the unique attributes that these models add, current challenges and therapeutic significance.

Patient-Derived Xenotransplant of CNS Neoplasms in Zebrafish: A Systematic Review

Glioblastoma and neuroblastoma are the most common central nervous system malignant tumors in adult and pediatric populations. Both are associated with poor survival. These tumors are highly heterogeneous, having complex interactions among different cells within the tumor and with the tumor microenvironment. One of the main challenges in the neuro-oncology field is achieving optimal conditions to evaluate a tumor’s molecular genotype and phenotype. In this respect, the zebrafish biological model is becoming an excellent alternative for studying carcinogenic processes and discovering new treatments. This review aimed to describe the results of xenotransplantation of patient-derived CNS tumors in zebrafish models. The reviewed studies show that it is possible to maintain glioblastoma and neuroblastoma primary cell cultures and transplant the cells into zebrafish embryos. The zebrafish is a suitable biological model for understanding tumor progression and the effects of different treatments. This model offers new perspectives in providing personalized care and improving outcomes for patients living with central nervous system tumors.

Assessing Molecular Regulation of Vascular Permeability Using a VEGF-Inducible Zebrafish Model

Vascular endothelial growth factor (VEGF) stimulates vascular permeability in a variety of human pathologies, such as cancer, ischemic stroke, cardiovascular disease, retinal conditions, and COVID-19-associated pulmonary edema, sepsis, acute lung injury, and acute respiratory distress syndrome. Comprehensive investigation of the molecular mechanisms of VEGF-induced vascular permeability has been hindered by the lack of in vivo models that easily facilitate genetic manipulation studies in real time. To address this need, we generated a heat-inducible VEGF transgenic zebrafish model of vascular permeability. Here, we describe how this zebrafish model can be used to monitor VEGF-induced vascular permeability through live in vivo imaging to identify genetic regulators that play key roles in vascular barrier integrity in physiological conditions and human disease processes.

Suppressing STAT3 activity protects the endothelial barrier from VEGF-mediated vascular permeability

Vascular permeability triggered by inflammation or ischemia promotes edema, exacerbates disease progression and impairs tissue recovery. Vascular endothelial growth factor (VEGF) is a potent inducer of vascular permeability. VEGF plays an integral role in regulating vascular barrier function physiologically and in pathologies, including cancer, stroke, cardiovascular disease, retinal conditions and COVID-19-associated pulmonary edema, sepsis and acute lung injury. Understanding temporal molecular regulation of VEGF-induced vascular permeability will facilitate developing therapeutics to inhibit vascular permeability, while preserving tissue-restorative angiogenesis. Here, we demonstrate that VEGF signals through signal transducer and activator of transcription 3 (STAT3) to promote vascular permeability. We show that genetic STAT3 ablation reduces vascular permeability in STAT3-deficient endothelium of mice and VEGF-inducible zebrafish crossed with CRISPR/Cas9-generated Stat3 knockout zebrafish. Intercellular adhesion molecule 1 (ICAM-1) expression is transcriptionally regulated by STAT3, and VEGF-dependent STAT3 activation is regulated by JAK2. Pyrimethamine, an FDA-approved antimicrobial agent that inhibits STAT3-dependent transcription, substantially reduces VEGF-induced vascular permeability in zebrafish, mouse and human endothelium. Collectively, our findings suggest that VEGF/VEGFR-2/JAK2/STAT3 signaling regulates vascular barrier integrity, and inhibition of STAT3-dependent activity reduces VEGF-induced vascular permeability.

This article has an associated First Person interview with the first author of the paper.

Summary: Genetic STAT3 ablation in mice and VEGF-inducible zebrafish reveals that VEGF signals through STAT3 to promote vascular permeability. Pyrimethamine reduces VEGF-induced permeability in animal models.

Zebrafish Avatar to Develop Precision Breast Cancer Therapies

BACKGROUND

Zebrafish (Danio rerio) is a vertebrate that has become a popular alternative model for the cellular and molecular study of human tumors and for drug testing and validating approaches. Notably, zebrafish embryos, thanks to their accessibility, allow rapid collection of in vivo results prodromal to validation in the murine models in respect to the 3R principles. The generation of tumor xenograft in zebrafish embryos and larvae, or zebrafish avatar, represents a unique opportunity to study tumor growth, angiogenesis, cell invasion and metastatic dissemination, interaction between tumor and host in vivo avoiding immunogenic rejection, representing a promising platform for the translational research and personalized therapies.

OBJECTIVE

In this mini-review we report recent advances in breast cancer research and drug testing that took advantage of the zebrafish xenograft model using both breast cancer cell lines and patient's biopsy.

CONCLUSION

Patient derived xenograft, together with the gene editing, the omics biotechnology, the in vivo time lapse imaging and the high-throughput screening that are already set up and largely used in zebrafish, could represent a step forward towards precision and personalized medicine in the breast cancer research field.

Image-based profiling for drug discovery: due for a machine-learning upgrade?

Image-based profiling is a maturing strategy by which the rich information present in biological images is reduced to a multidimensional profile, a collection of extracted image-based features. These profiles can be mined for relevant patterns, revealing unexpected biological activity that is useful for many steps in the drug discovery process. Such applications include identifying disease-associated screenable phenotypes, understanding disease mechanisms and predicting a drug's activity, toxicity or mechanism of action. Several of these applications have been recently validated and have moved into production mode within academia and the pharmaceutical industry. Some of these have yielded disappointing results in practice but are now of renewed interest due to improved machine-learning strategies that better leverage image-based information. Although challenges remain, novel computational technologies such as deep learning and single-cell methods that better capture the biological information in images hold promise for accelerating drug discovery.

Studying the Tumor Microenvironment in Zebrafish

The tumor microenvironment significantly contributes to tumor initiation, progression, neo-angiogenesis, and metastasis, and a better understanding of the role of the different cellular players would facilitate the development of novel therapeutic strategies for cancer treatment. Towards this goal, intravital imaging is a powerful method to unravel interaction partners of tumor cells. Among vertebrate model organisms, zebrafish is uniquely suited for in vivo imaging studies. In recent years zebrafish has also become a valuable model in cancer research. In this chapter, we will summarize, how zebrafish has been used to characterize cells of the tumor microenvironment. We will cover both genetically engineered cancer models and xenograft models in zebrafish. The majority of work has been done on the role of innate immune cells and their role during tumor initiation and metastasis, but we will also cover studies focusing on adipocytes, fibroblasts, and endothelial cells. Taken together, we will highlight the versatile use of the zebrafish model for in vivo tumor microenvironment studies.

Sialyltransferase Inhibitors Suppress Breast Cancer Metastasis

We report the synthesis and evaluation of a series of cell-permeable and N- versus O-selective sialyltransferase inhibitors. Inhibitor design entailed the functionalization of lithocholic acid at C(3) and at the cyclopentane ring side chain. Among the series, FCW34 and FCW66 were shown to inhibit MDA-MB-231 cell migration as effectively as ST3GALIII-gene knockdown did. FCW34 was shown to inhibit tumor growth, reduce angiogenesis, and delay cancer cell metastasis in animal models. Furthermore, FCW34 inhibited vessel development and suppressed angiogenic activity in transgenic zebrafish models. Our results provide clear evidence that FCW34-induced sialyltransferase inhibition reduces cancer cell metastasis by decreasing N-glycan sialylation, thus altering the regulation of talin/integrin/FAK/paxillin and integrin/NFκB signaling pathways.

CircCDKN2B-AS1 interacts with IMP3 to stabilize hexokinase 2 mRNA and facilitate cervical squamous cell carcinoma aerobic glycolysis progression

Background

Circular RNAs (circRNAs) have been reported to play key roles in the development of various cancers. However, the biological functions and clinical significance of most circRNAs are still elusive. The purpose of this study was to explore the function and mechanism of a certain circRNA named circCDKN2B-AS1 in cervical cancer development and its potential value in the clinic.

Methods

qRT-PCR was used to verify the expression level of circCDKN2B-AS1. CCK-8, Transwell, and flow cytometry (FCM) assays were performed to detect cellular proliferation, migration, and apoptosis, respectively. A Seahorse XFe96 Analyzer was used to measure glycolysis metabolism level. RNA pull-down, RNA immunoprecipitation (RIP), actinomycin-D addition assays and Western blotting were used to screen and elucidate the potential mechanisms involved. BALB/c nude mice and zebrafish embryos (AB, WT) were used as animal models to investigate tumorigenesis capability. ¹⁸FDG-microPET/CT imaging and lactic acid (LA) and pyruvic acid (PA) content detection assays were used to detect the level of glucose metabolism in subcutaneous tumors from nude mice.

Results

CircCDKN2B-AS1, a circular isoform of the long noncoding RNA (lncRNA) CDKN2B-AS1, was upregulated in cervical cancer and precancerous tissues. We found that circCDKN2B-AS1 associated with the IMP3 protein depending on a specific binding site and regulated the stability of Hexokinase 2 (HK2) mRNA, the rate-limiting enzyme of the aerobic glycolysis pathway. The expression level of circCDKN2B-AS1 fated the binding of IMP3 to the 3′ untranslated region (UTR) of HK2 mRNA, consequently affecting the malignant cell phenotype and aerobic glycolysis in cervical cancer in vitro and in vivo. Mutant circCDKN2B-AS1, lacking the IMP3 binding site, did not have such effects. Utilization of an inhibitory peptide to block the interaction between circCDKN2B-AS1 and the IMP3 protein impeded the binding of IMP3 to the 3’UTR of HK2 mRNA and suppressed aerobic glycolysis in cervical cancer cells.

Conclusions

Our findings demonstrate that circCDKN2B-AS1 facilitates aerobic glycolysis by sponging the IMP3 protein to stabilize HK2 mRNA, consequently promoting the malignant phenotype in cervical cancer, which may provide a potential approach for cervical cancer therapeutics.

Suppressing STAT3 activity protects the endothelial barrier from VEGF-mediated vascular permeability

Vascular permeability triggered by inflammation or ischemia promotes edema, exacerbates disease progression, and impairs tissue recovery. Vascular endothelial growth factor (VEGF) is a potent inducer of vascular permeability. VEGF plays an integral role in regulating vascular barrier function physiologically and in pathologies, such as cancer, ischemic stroke, cardiovascular disease, retinal conditions, and COVID-19-associated pulmonary edema and sepsis, which often leads to acute lung injury, including acute respiratory distress syndrome. However, after initially stimulating permeability, VEGF subsequently mediates angiogenesis to repair damaged tissue. Consequently, understanding temporal molecular regulation of VEG-Finduced vascular permeability will facilitate developing therapeutics that achieve the delicate balance of inhibiting vascular permeability while preserving tissue repair. Here, we demonstrate that VEGF signals through signal transducer and activator of transcription 3 (STAT3) to promote vascular permeability. Specifically, we show that genetic STAT3 ablation reduces vascular permeability in STAT3-deficient endothelium of mice and VEGF-inducible zebrafish crossed with CRISPR/Cas9 generated genomic STAT3 knockout zebrafish. Importantly, STAT3 deficiency does not impair vascular development and function in vivo. We identify intercellular adhesion molecule 1 (ICAM-1) as a STAT3-dependent transcriptional regulator and show VEGF-dependent STAT3 activation is regulated by JAK2. Pyrimethamine, an FDA-approved antimicrobial agent that inhibits STAT3-dependent transcription, substantially reduces VEGF-induced vascular permeability in zebrafish, mouse, and human endothelium. Indeed, pharmacologically targeting STAT3 increases vascular barrier integrity using two additional compounds, atovaquone and C188-9. Collectively, our findings suggest that the VEGF, VEGFR-2, JAK2, and STAT3 signaling cascade regulates vascular barrier integrity, and inhibition of STAT3-dependent activity reduces VEGF-induced vascular permeability in vertebrate models.

Rapid In Vivo Validation of HDAC Inhibitor-Based Treatments in Neuroblastoma Zebrafish Xenografts

The survival rate among children with relapsed neuroblastomas continues to be poor, and thus new therapeutic approaches identified by reliable preclinical drug testing models are urgently needed. Zebrafish are a powerful vertebrate model in preclinical cancer research. Here, we describe a zebrafish neuroblastoma yolk sac model to evaluate efficacy and toxicity of histone deacetylase (HDAC) inhibitor treatments. Larvae were engrafted with fluorescently labeled, genetically diverse, established cell lines and short-term cultures of patient-derived primary cells. Engrafted tumors progressed locally and disseminated remotely in an intact environment. Combination treatments involving the standard chemotherapy doxorubicin and HDAC inhibitors substantially reduced tumor volume, induced tumor cell death, and inhibited tumor cell dissemination to the tail region. Hence, this model allows for fast, cost-efficient, and reliable in vivo evaluation of toxicity and response of the primary and metastatic tumor sites to drug combinations.

Modeling Cancer Using Zebrafish Xenografts: Drawbacks for Mimicking the Human Microenvironment

The first steps towards establishing xenografts in zebrafish embryos were performed by Lee et al., 2005 and Haldi et al., 2006, paving the way for studying human cancers using this animal species. Since then, the xenograft technique has been improved in different ways, ranging from optimizing the best temperature for xenografted embryo incubation, testing different sites for injection of human tumor cells, and even developing tools to study how the host interacts with the injected cells. Nonetheless, a standard protocol for performing xenografts has not been adopted across laboratories, and further research on the temperature, microenvironment of the tumor or the cell-host interactions inside of the embryo during xenografting is still needed. As a consequence, current non-uniform conditions could be affecting experimental results in terms of cell proliferation, invasion, or metastasis; or even overestimating the effects of some chemotherapeutic drugs on xenografted cells. In this review, we highlight and raise awareness regarding the different aspects of xenografting that need to be improved in order to mimic, in a more efficient way, the human tumor microenvironment, resulting in more robust and accurate in vivo results.

Use of zebrafish embryos as avatar of patients with pancreatic cancer: A new xenotransplantation model towards personalized medicine

BACKGROUND

The response to chemotherapy treatment of patients with pancreatic ductal adenocarcinoma (PDAC) is difficult to predict and the identification of patients who most likely will benefit from aggressive chemotherapy approaches is crucial. The concept of personalized medicine has emerged in the last years with the objective to tailor the medical treatment to the individual characteristics of each patient, and particularly to the tumor biology of each patient. The need for in-vivo xenotransplantation models for cancer patients has increased exponentially, and for this reason zebrafish avatars have gained popularity. Preliminary studies were conducted also with PDAC tissue.

AIM

To develop a simple, not expensive, diffusible zebrafish embryo model as avatar for patients affected by PDAC.

METHODS

Tumor tissue was taken from the surgical specimen by the histopathologist. After its fragmentation into small pieces, they are stained with CM-Dil. Small pieces of stained tissue were transplanted into the yolk of wt AB zebrafish embryos with a glass capillary needle. Embryos were incubated at 35 °C in E3 medium supplemented with 1% Pen/Strep in the presence or absence of drugs for the following days in respect of the treatment plan (Gemcitabine; Gemcitabine and Oxaliplatin; Gemcitabine and nab-Paclitaxel; 5-Fluorouracil and Folinic acid and Oxaliplatin and Irinotecan). The response of zebrafish xenografts to the chemotherapy options has been analyzed by monitoring the fluorescent stained area at 2 h post injection (hpi), 1 d and 2 d post injection (dpi). In each time point, the mean size of the stained area was measured by ImageJ and it was normalized with respect to the 1 dpi time point mean relative tumor area (RTA). We evaluated the effect of the chemotherapy exposition comparing the mean RTA of each treated subgroup and the control group and evaluating the percentage reduction of the mean RTA by comparing each treated subgroup with the control group.

RESULTS

Between July 2018 and October 2019, a total of 15 patients with pancreatic cancer were prospectively enrolled. In all cases, it was possible to take a fragment of the tumor from the surgical specimen for the xenotransplantation in the zebrafish embryos. The histological examination confirmed the presence of a PDAC in all cases. In absence of chemotherapy (control group), over time the Dil-stained area showed a statistically significant increase in all cases. A statistically significant reduction of the mean RTA in the treated subgroups for at least one chemotherapy scheme was reported in 6/15 (40%) cases. The analysis of the percentage reduction of the RTA in treated subgroups in comparison to the control group revealed the presence of a linear relationship in each subgroup between the percentage reduction of the RTA and the number of cases reporting each percentage threshold considered for the analysis.

CONCLUSION

Our model seems to be effective for the xenotransplantation of PDAC tissue and evaluation of the effect of each chemotherapy scheme on the xenotransplanted tumor tissue.

Zebrafish Xenografts for Drug Discovery and Personalized Medicine

Cancer is the second leading cause of death in the world. Given that cancer is a highly individualized disease, predicting the best chemotherapeutic treatment for individual patients can be difficult. Ex vivo models such as mouse patient-derived xenografts (PDX) and organoids are being developed to predict patient-specific chemosensitivity profiles before treatment in the clinic. Although promising, these models have significant disadvantages including long growth times that introduce genetic and epigenetic changes to the tumor. The zebrafish xenograft assay is ideal for personalized medicine. Imaging of the small, transparent fry is unparalleled among vertebrate organisms. In addition, the speed (5-7 days) and small patient tissue requirements (100-200 cells per animal) are unique features of the zebrafish xenograft model that enable patient-specific chemosensitivity analyses.

Zebrafish Avatars towards Personalized Medicine-A Comparative Review between Avatar Models

Cancer frequency and prevalence have been increasing in the past decades, with devastating impacts on patients and their families. Despite the great advances in targeted approaches, there is still a lack of methods to predict individual patient responses, and therefore treatments are tailored according to average response rates. “Omics” approaches are used for patient stratification and choice of therapeutic options towards a more precise medicine. These methods, however, do not consider all genetic and non-genetic dynamic interactions that occur upon drug treatment. Therefore, the need to directly challenge patient cells in a personalized manner remains. The present review addresses the state of the art of patient-derived in vitro and in vivo models, from organoids to mouse and zebrafish Avatars. The predictive power of each model based on the retrospective correlation with the patient clinical outcome will be considered. Finally, the review is focused on the emerging zebrafish Avatars and their unique characteristics allowing a fast analysis of local and systemic effects of drug treatments at the single-cell level. We also address the technical challenges that the field has yet to overcome.

Zebrafish for Personalized Regenerative Medicine; A More Predictive Humanized Model of Endocrine Disease

Regenerative medicine is a multidisciplinary field that aims to determine different factors and develop various methods to regenerate impaired tissues, organs, and cells in the disease and impairment conditions. When treatment procedures are specified according to the individual's information, the leading role of personalized regenerative medicine will be revealed in developing more effective therapies. In this concept, endocrine disorders can be considered as potential candidates for regenerative medicine application. Diabetes mellitus as a worldwide prevalent endocrine disease causes different damages such as blood vessel damages, pancreatic damages, and impaired wound healing. Therefore, a global effort has been devoted to diabetes mellitus investigations. Hereupon, the preclinical study is a fundamental step. Up to now, several species of animals have been modeled to identify the mechanism of multiple diseases. However, more recent researches have been demonstrated that animal models with the ability of tissue regeneration are more suitable choices for regenerative medicine studies in endocrine disorders, typically diabetes mellitus. Accordingly, zebrafish has been introduced as a model that possesses the capacity to regenerate different organs and tissues. Especially, fine regeneration in zebrafish has been broadly investigated in the regenerative medicine field. In addition, zebrafish is a suitable model for studying a variety of different situations. For instance, it has been used for developmental studies because of the special characteristics of its larva. In this review, we discuss the features of zebrafish that make it a desirable animal model, the advantages of zebrafish and recent research that shows zebrafish is a promising animal model for personalized regenerative diseases. Ultimately, we conclude that as a newly introduced model, zebrafish can have a leading role in regeneration studies of endocrine diseases and provide a good perception of underlying mechanisms.

Zebrafish as a preclinical in vivo screening model for nanomedicines

The interactions of nanomedicines with biological environments is heavily influenced by their physicochemical properties. Formulation design and optimization are therefore key steps towards successful nanomedicine development. Unfortunately, detailed assessment of nanomedicine formulations, at a macromolecular level, in rodents is severely limited by the restricted imaging possibilities within these animals. Moreover, rodent in vivo studies are time consuming and expensive, limiting the number of formulations that can be practically assessed in any one study. Consequently, screening and optimisation of nanomedicine formulations is most commonly performed in surrogate biological model systems, such as human-derived cell cultures. However, despite the time and cost advantages of classical in vitro models, these artificial systems fail to reflect and mimic the complex biological situation a nanomedicine will encounter in vivo. This has acutely hampered the selection of potentially successful nanomedicines for subsequent rodent in vivo studies. Recently, zebrafish have emerged as a promising in vivo model, within nanomedicine development pipelines, by offering opportunities to quickly screen nanomedicines under in vivo conditions and in a cost-effective manner so as to bridge the current gap between in vitro and rodent studies. In this review, we outline several advantageous features of the zebrafish model, such as biological conservation, imaging modalities, availability of genetic tools and disease models, as well as their various applications in nanomedicine development. Critical experimental parameters are discussed and the most beneficial applications of the zebrafish model, in the context of nanomedicine development, are highlighted.

Developing zebrafish disease models for in vivo small molecule screens

The zebrafish is a model organism that allows in vivo studies to be performed at a scale usually restricted to in vitro studies. As such, the zebrafish is well suited to in vivo screens, in which thousands of small molecules are tested for their ability to modify disease phenotypes in zebrafish disease models. Numerous approaches have been developed for modeling human diseases in zebrafish, including mutagenesis, transgenesis, pharmacological approaches, wounding, and exposure to infectious or cancerous agents. We review the various strategies for modeling human diseases in zebrafish and discuss important considerations when developing zebrafish models for use in in vivo small molecule screens.

An efficient method to generate xenograft tumor models of acute myeloid leukemia and hepatocellular carcinoma in adult zebrafish

Zebrafish is emerging as a promising model for the study of human cancers. Several xenograft models of zebrafish have been developed, particularly in larval stages (<48 h post fertilization) when the immune system of fish is not developed. However, xenografting in adult zebrafish requires laborious and transient methods of immune suppression (γ- irradiation or dexamethasone) that limits engraftment and survival of the tumor or fail to recapitulate specific characteristics of malignancies. Thus, the availability of a simple protocol to successfully engraft adult zebrafish, remains a challenge. The current study addresses this limitation and describes a robust method of xenografting in adult zebrafish. We describe a protocol that involves pre-conditioning of Casper, a pigmentation mutant of zebrafish with busulfan that led to a higher rate of engraftment of hepatocellular carcinoma and acute myeloid leukemia cells. To further ascertain the homing characteristics of the injected cancer cells, we transplanted adult zebrafish by two routes of administration and then studied their compartmentalization. This model presents a valuable alternative to rodents to study the biology of these cancers and also a cost-effective platform for evaluation of potential anti-cancer agents.

2-Ethoxycarbonyl-2-β-hydroxy-a-nor-cholest-5-ene-4one: Extraction, structural characterization, antimicrobial, antioxidant, anticancer and acute toxicity studies

Identification and characterization of marine natural products with antimicrobial, antioxidant activity with minimal toxicity has received much interest over the past few years. Among, Acropora formosa is one of the unexplored marine organism for the screening of natural products in marine resources. In this study, a novel steroid 2-ethoxycarbonyl-2-β-hydroxy-A-nor-cholest-5-ene-4one (ECHC) was isolated from butanol extracts of A. formosa using vacuum liquid chromatography and sequentially purified by column chromatography. The chemical structure of the compound was elucidated based on spectroscopic analysis including GC-MS, ¹H NMR and ¹³C NMR and identified as ECHC. Moreover, in vitro antioxidant activity showed that ECHC was highly scavenged the oxidative stress generative molecules. The in vitro cytotoxic activity of ECHC showed excellent activity against human breast cancer cells. Further, in vivo acute toxicity of ECHC on zebrafish Danio rerio was showed no toxicity as well as no morphological damage was observed after 21 days exposure. Histological analysis revealed that there is no apparent difference was observed between ECHC exposure and control group of D. rerio. Together, these results confirmed that ECHC has in vitro antioxidant and anticancer activity and could be developed as a potential drug against most contagious disease like cancer.

Zebrafish: Speeding Up the Cancer Drug Discovery Process

Zebrafish (Danio rerio) is an ideal in vivo model to study a wide variety of human cancer types. In this review, we provide a comprehensive overview of zebrafish in the cancer drug discovery process, from (i) approaches to induce malignant tumors, (ii) techniques to monitor cancer progression, and (iii) strategies for compound administration to (iv) a compilation of the 355 existing case studies showing the impact of zebrafish models on cancer drug discovery, which cover a broad scope of scenarios. Finally, based on the current state-of-the-art analysis, this review presents some highlights about future directions using zebrafish in cancer drug discovery and the potential of this model as a prognostic tool in prospective clinical studies. Cancer Res; 78(21); 6048-58. ©2018 AACR.

BMI1 Drives Metastasis of Prostate Cancer in Caucasian and African-American Men and Is A Potential Therapeutic Target: Hypothesis Tested in Race-specific Models

PURPOSE

Metastasis is the major cause of mortality in prostate cancer patients. Factors such as genetic makeup and race play critical role in the outcome of therapies. This study was conducted to investigate the relevance of BMI1 in metastatic prostate cancer disease in Caucasian and African-Americans.

EXPERIMENTAL DESIGN

We employed race-specific prostate cancer models, clinical specimens, clinical data mining, gene-microarray, transcription-reporter assay, chromatin-immunoprecipitation (ChIP), IHC, transgenic-(tgfl/fl) zebrafish, and mouse metastasis models.

RESULTS

BMI1 expression was observed to be elevated in metastatic tumors (lymph nodes, lungs, bones, liver) of Caucasian and African-American prostate cancer patients. The comparative analysis of stage III/IV tumors showed an increased BMI1 expression in African-Americans than Caucasians. TCGA and NIH/GEO clinical data corroborated to our findings. We show that BMI1 expression (i) positively correlates to metastatic (MYC, VEGF, cyclin D1) and (ii) negative correlates to tumor suppressor (INKF4A/p16, PTEN) levels in tumors. The correlation was prominent in African-American tumors. We show that BMI1 regulates the transcriptional activation of MYC, VEGF, INKF4A/p16, and PTEN. We show the effect of pharmacological inhibition of BMI1 on the metastatic genome and invasiveness of tumor cells. Next, we show the anti-metastatic efficacy of BMI1-inhibitor in transgenic zebrafish and mouse metastasis models. Docetaxel as monotherapy has poor outcome on the growth of metastatic tumors. BMI1 inhibitor as an adjuvant improved the taxane therapy in race-based in vitro and in vivo models.

CONCLUSIONS

BMI1, a major driver of metastasis, represents a promising therapeutic target for treating advanced prostate cancer in patients (including those belonging to high-risk group).

In silico cancer research towards 3R

BACKGROUND

Improving our understanding of cancer and other complex diseases requires integrating diverse data sets and algorithms. Intertwining in vivo and in vitro data and in silico models are paramount to overcome intrinsic difficulties given by data complexity. Importantly, this approach also helps to uncover underlying molecular mechanisms. Over the years, research has introduced multiple biochemical and computational methods to study the disease, many of which require animal experiments. However, modeling systems and the comparison of cellular processes in both eukaryotes and prokaryotes help to understand specific aspects of uncontrolled cell growth, eventually leading to improved planning of future experiments. According to the principles for humane techniques milestones in alternative animal testing involve in vitro methods such as cell-based models and microfluidic chips, as well as clinical tests of microdosing and imaging. Up-to-date, the range of alternative methods has expanded towards computational approaches, based on the use of information from past in vitro and in vivo experiments. In fact, in silico techniques are often underrated but can be vital to understanding fundamental processes in cancer. They can rival accuracy of biological assays, and they can provide essential focus and direction to reduce experimental cost.

MAIN BODY

We give an overview on in vivo, in vitro and in silico methods used in cancer research. Common models as cell-lines, xenografts, or genetically modified rodents reflect relevant pathological processes to a different degree, but can not replicate the full spectrum of human disease. There is an increasing importance of computational biology, advancing from the task of assisting biological analysis with network biology approaches as the basis for understanding a cell's functional organization up to model building for predictive systems.

CONCLUSION

Underlining and extending the in silico approach with respect to the 3Rs for replacement, reduction and refinement will lead cancer research towards efficient and effective precision medicine. Therefore, we suggest refined translational models and testing methods based on integrative analyses and the incorporation of computational biology within cancer research.