Animal models of disease: pre-clinical animal models of cancer and their applications and utility in drug discovery

Precision Oncology Beyond Genomics: The Future Is Here-It Is Just Not Evenly Distributed

Cancer is a multifactorial disease with increasing incidence. There are more than 100 different cancer types, defined by location, cell of origin, and genomic alterations that influence oncogenesis and therapeutic response. This heterogeneity between tumors of different patients and also the heterogeneity within the same patient's tumor pose an enormous challenge to cancer treatment. In this review, we explore tumor heterogeneity on the longitudinal and the latitudinal axis, reviewing current and future approaches to study this heterogeneity and their potential to support oncologists in tailoring a patient's treatment regimen. We highlight how the ideal of precision oncology is reaching far beyond the knowledge of genetic variants to inform clinical practice and discuss the technologies and strategies already available to improve our understanding and management of heterogeneity in cancer treatment. We will focus on integrating multi-omics technologies with suitable in vitro models and their proficiency in mimicking endogenous tumor heterogeneity.

Proof-of-Concept Study of Multifunctional Hybrid Nanoparticle System Combined with NIR Laser Irradiation for the Treatment of Melanoma

The global impact of cancer emphasizes the importance of developing innovative, effective and minimally invasive therapies. In the context of superficial cancers, the development of a multifunctional nanoparticle-based system and its in vitro and in vivo safety and efficacy characterization are, herein, proposed as a proof-of-concept. This multifunctional system consists of gold nanoparticles coated with hyaluronic and oleic acids, and functionalized with epidermal growth factor for greater specificity towards cutaneous melanoma cells. This nanoparticle system is activated by a near-infrared laser. The characterization of this nanoparticle system included several phases, with in vitro assays being firstly performed to assess the safety of gold nanoparticles without laser irradiation. Then, hairless immunocompromised mice were selected for a xenograft model upon inoculation of A375 human melanoma cells. Treatment with near-infrared laser irradiation for five minutes combined with in situ administration of the nanoparticles showed a tumor volume reduction of approximately 80% and, in some cases, led to the formation of several necrotic foci, observed histologically. No significant skin erythema at the irradiation zone was verified, nor other harmful effects on the excised organs. In conclusion, these assays suggest that this system is safe and shows promising results for the treatment of superficial melanoma.

Bone-on-a-chip: microfluidic technologies and microphysiologic models of bone tissue

Bone is an active organ that continuously undergoes an orchestrated process of remodeling throughout life. Bone tissue is uniquely capable of adapting to loading, hormonal, and other changes happening in the body, as well as repairing bone that becomes damaged to maintain tissue integrity. On the other hand, diseases such as osteoporosis and metastatic cancers disrupt normal bone homeostasis leading to compromised function. Historically, our ability to investigate processes related to either physiologic or diseased bone tissue has been limited by traditional models that fail to emulate the complexity of native bone. Organ-on-a-chip models are based on technological advances in tissue engineering and microfluidics, enabling the reproduction of key features specific to tissue microenvironments within a microfabricated device. Compared to conventional in-vitro and in-vivo bone models, microfluidic models, and especially organs-on-a-chip platforms, provide more biomimetic tissue culture conditions, with increased predictive power for clinical assays. In this review, we will report microfluidic and organ-on-a-chip technologies designed for understanding the biology of bone as well as bone-related diseases and treatments. Finally, we discuss the limitations of the current models and point toward future directions for microfluidics and organ-on-a-chip technologies in bone research.

In Vitro and In Vivo Tumor Models for the Evaluation of Anticancer Nanoparticles

Multiple studies about tumor biology have revealed the determinant role of the tumor microenvironment in cancer progression, resulting from the dynamic interactions between tumor cells and surrounding stromal cells within the extracellular matrix. This malignant microenvironment highly impacts the efficacy of anticancer nanoparticles by displaying drug resistance mechanisms, as well as intrinsic physical and biochemical barriers, which hamper their intratumoral accumulation and biological activity.Currently, two-dimensional cell cultures are used as the initial screening method in vitro for testing cytotoxic nanocarriers. However, this fails to mimic the tumor heterogeneity, as well as the three-dimensional tumor architecture and pathophysiological barriers, leading to an inaccurate pharmacological evaluation.Biomimetic 3D in vitro tumor models, on the other hand, are emerging as promising tools for more accurately assessing nanoparticle activity, owing to their ability to recapitulate certain features of the tumor microenvironment and thus provide mechanistic insights into nanocarrier intratumoral penetration and diffusion rates.Notwithstanding, in vivo validation of nanomedicines remains irreplaceable at the preclinical stage, and a vast variety of more advanced in vivo tumor models is currently available. Such complex animal models (e.g., genetically engineered mice and patient-derived xenografts) are capable of better predicting nanocarrier clinical efficiency, as they closely resemble the heterogeneity of the human tumor microenvironment.Herein, the development of physiologically more relevant in vitro and in vivo tumor models for the preclinical evaluation of anticancer nanoparticles will be discussed, as well as the current limitations and future challenges in clinical translation.

Patient-derived ovarian cancer explants: preserved viability and histopathological features in long-term agitation-based cultures

Ovarian carcinoma (OvC) remains a major therapeutic challenge due to its propensity to develop resistance after an initial response to chemotherapy. Interactions of tumour cells with the surrounding microenvironment play a role in tumour survival, invasion capacity and drug resistance. Cancer models that retain tissue architecture and tumour microenvironment components are therefore essential to understand drug response and resistance mechanisms. Herein, our goal was to develop a long-term OvC patient-derived explant (OvC-PDE) culture strategy in which architecture and cell type heterogeneity of the original tumour would be retained. Samples from 25 patients with distinct OvC types and one with a benign tumour, were cultured for 30 days in agitation-based culture systems with 100% success rate. OvC-PDE cultures retained the original tumour architecture and main cellular components: epithelial cells, fibroblasts and immune cells. Epithelial cells kept their original levels of proliferation and apoptosis. Moreover, the major extracellular components, such as collagen-I and -IV, were retained in explants. OvC-PDE cultures were exposed to standard-of-care chemotherapeutics agents for 2 weeks, attesting the ability of the platform for drug assays employing cyclic drug exposure regimens. We established an OvC-PDE dynamic culture in which tumour architecture and cell type heterogeneity were preserved for the different OvC types, replicating features of the original tumour and compatible with long-term drug exposure for drug efficacy and resistance studies.

New technologies in developing recombinant-attenuated bacteria for cancer therapy

Cancer has always been a global problem, with more cases of cancer patients being diagnosed every year. Conventional cancer treatments, including radiotherapy, chemotherapy, and surgery, are still unable to bypass their obvious limitations, and developing effective targeted therapies is still required. More than one century ago, the doctor William B. Coley discovered that cancer patients had tumor regression by injection of Streptococcus bacteria. The studies of cancer therapy using bacterial microorganisms are now very widespread. In particular, the facultative anaerobic bacteria Salmonella typhimurium is widely investigated as it can selectively colonize different types of tumors, locally deliver various antitumor drugs, and inhibit tumor growth. The exciting antitumor efficacy and safety observed in animal tumor models prompted the well-known attenuated Salmonella bacterial strain VNP20009 to be tested in human clinical trials in the early 21st century. Regrettably, no patients showed significant therapeutic effects and even bacterial colonization in tumor tissue was undetectable in most patients. Salmonella bacteria are still considered as a promising agent or vehicle for cancer therapy. Recent efforts have been focused on the generation of attenuated bacterial strains with higher targeting for tumor tissue, and optimization of the delivery of therapeutic antitumor cargoes into the tumor microenvironment. This review will summarize new technologies or approaches that may improve bacteria-mediated cancer therapy.

Establishment and Characterization of Canine Mammary Gland Carcinoma Cell Lines With Vasculogenic Mimicry Ability in vitro and in vivo

Mammary tumors affect intact and elderly female dogs, and almost 50% of these cases are malignant. Cell culture offers a promising preclinical model to study this disease and creates the opportunity to deposit cell lines at a cell bank to allow greater assay reproducibility and more reliable validation of the results. Another important aspect is the possibility of establishing models and improving our understanding of tumor characteristics, such as vasculogenic mimicry. Because of the importance of cancer cell lines in preclinical models, the present study established and characterized primary cell lines from canine mammary gland tumors. Cell cultures were evaluated for morphology, phenotype, vasculogenic mimicry (VM), and tumorigenicity abilities. We collected 17 primary mammary carcinoma and three metastases and obtained satisfactory results from 10 samples. The cells were transplanted to a xenograft model. All cell lines exhibited a spindle-shaped or polygonal morphology and expressed concomitant pancytokeratin and cytokeratin 8/18. Four cell lines had vasculogenic mimicry ability in vitro, and two cell lines showed in vivo tumorigenicity and VM in the xenotransplanted tumor. Cellular characterization will help create a database to increase our knowledge of mammary carcinomas in dogs, including studies of tumor behavior and the identification of new therapeutic targets.

Relevance of humanized three-dimensional tumor tissue models: a descriptive systematic literature review

Despite numerous advances in tumor screening, diagnosis, and treatment, to date, tumors remain one of the leading causes of death, principally due to metastasis and the physiological damage produced by tumor growth. Among the main limits related to the study of tumor physiology there is the complex and heterogeneity nature of its environment and the absence of relevant, simple and inexpensive models able to mimic the biological processes occurring in patients allowing the correct clinical translation of results. To enhance the understanding of the mechanisms of tumors and to develop and evaluate new therapeutic approaches the set-up of advanced and alternative models is mandatory. One of the more translational approaches seems to be the use of humanized three-dimensional (3D) tissue culture. This model allows to accurately mimic tumor morphology and biology, maintaining the native microenvironment without any manipulation. However, little is still known on the real clinical relevance of these models for the study of tumor mechanisms and for the screening of new therapy. The aim of this descriptive systematic literature review was to evaluate and summarize the current knowledge on human 3D tumor tissue culture models. We reviewed the strategies employed by researchers to set-up these systems, also considering the different approaches and culture conditions used. All these aspects greatly contribute to the existing knowledge on tumors, providing a specific link to clinical scenarios and making the humanized 3D tumor tissue models a more attractive tool both for researchers and clinicians.

Use of translational modeling and simulation for quantitative comparison of PF-06804103, a new generation HER2 ADC, with Trastuzumab-DM1

A modeling and simulation approach was used for quantitative comparison of a new generation HER2 antibody drug conjugate (ADC, PF-06804103) with trastuzumab-DM1 (T-DM1). To compare preclinical efficacy, the pharmacokinetic (PK)/pharmacodynamic (PD) relationship of PF-06804103 and T-DM1 was determined across a range of mouse tumor xenograft models, using a tumor growth inhibition model. The tumor static concentration was assigned as the minimal efficacious concentration. PF-06804103 was concluded to be more potent than T-DM1 across cell lines studied. TSCs ranged from 1.0 to 9.8 µg/mL (n = 7) for PF-06804103 and from 4.7 to 29 µg/mL (n = 5) for T-DM1. Two experimental models which were resistant to T-DM1, responded to PF-06804103 treatment. A mechanism-based target mediated drug disposition (TMDD) model was used to predict the human PK of PF-06804103. This model was constructed and validated based on T-DM1 which has non-linear PK at doses administered in the clinic, driven by binding to shed HER2. Non-linear PK is predicted for PF-06804103 in the clinic and is dependent upon circulating HER2 extracellular domain (ECD) concentrations. The models were translated to human and suggested greater efficacy for PF-06804103 compared to T-DM1. In conclusion, a fit-for-purpose translational PK/PD strategy for ADCs is presented and used to compare a new generation HER2 ADC with T-DM1.

Preclinical Applications of Magnetic Resonance Imaging in Oncology

The evolving possibilities of molecular imaging (MI) are fundamentally changing the way we look at cancer, with imaging paradigms now shifting away from basic morphological measures toward the longitudinal assessment of functional, metabolic, cellular, and molecular information in vivo. Recent developments of imaging methodology and probe molecules utilizing the vast number of novel animal models of human cancers have enhanced our ability to non-invasively characterize neoplastic tissue and follow anticancer treatments. While preclinical molecular imaging offers a whole palette of excellent methodology to choose from, we will focus on magnetic resonance imaging (MRI) techniques, since they provide excellent molecular imaging capabilities and bear high potential for clinical translation. Prerequisites and consequences of using animal models as surrogates of human cancers in preclinical molecular imaging are outlined. We present physical principles, values, and limitations of MRI as molecular imaging modality and comment on its high potential to non-invasively assess information on metabolism, hypoxia, angiogenesis, and cell trafficking in preclinical cancer research.

Comparing the fate of brain metastatic breast cancer cells in different immune compromised mice with cellular magnetic resonance imaging

Metastasis is the leading cause of mortality in breast cancer patients, with brain metastases becoming increasingly prevalent. Studying this disease is challenging due to the limited experimental models and methods available. Here, we used iron-based cellular MRI to track the fate of a mammary carcinoma cell line (MDA-MB-231-BR) in vivo to characterize the growth of brain metastases in the nude and severely immune-compromised NOD/SCID/ILIIrg-/- (NSG) mouse. Nude and NSG mice received injections of iron-labeled MDA-MB-231-BR cells. Images were acquired with a 3T MR system and assessed for signal voids and metastases. The percentage of signal voids and the number and volume of metastases were quantified. Ex vivo imaging of the liver, histology, and immunofluorescence labeling was performed. Brain metastases grew more rapidly in NSG mice. At day 21 post cell injection, the average number of brain tumors in NSG mice was approximately four times greater than in nude mice. The persistence of iron-labeled cells, visualized as signal voids by MRI, was also examined. The percentage of voids decreased significantly over time for both nude and NSG mice. Body images revealed that the NSG mice also had metastases in the liver, lungs, and lymph nodes while tumors were only detected in the brains of nude mice. This work demonstrates the advantages of using the highly immune-compromised NSG mouse to study breast cancer metastasis, treatments aimed at inhibiting metastasis and outgrowth of breast cancer metastases in multiple organs, and the role that imaging can play toward credentialing these models that cannot be done with other in vitro or histopathologic methods alone.

Development of a Novel Orthotopic Primary Human Chordoma Xenograft Model: A Relevant Support for Future Research on Chordoma

Chordomas are slow-growing rare malignant neoplasms. The aim of this study was to establish a primary model of chordoma in the lumbosacral orthotopic area, to compare the growth rate to the subcutaneous site, and to show that this new graft site optimizes tumor growth and bony invasion. Eleven chordoma samples were transplanted subcutaneously in the flank and/or in contact with the lumbosacral region and grown into nude mice. Engraftment rate was significantly more successful in the lumbosacral environment compared with the flank at P0. Two xenografts from 2 patients showed bone invasion. One tumor was maintained through multiple rounds of serial transplantation, creating a model for study. Histological and immunostaining analysis confirmed that tumor grafts recapitulated the primary tumor from which they were derived, consisting of a myxoid chordoma expressing brachyury, cytokeratin AE1, EMA, and VEGF. Clear destruction of the bone by the tumor cells could be demonstrated. Molecular studies revealed PIK3CA and PTEN mutations involved in PI3K signaling pathway and most of the frequently reported chromosomal alterations. We present a novel orthotopic primary xenograft model of chordoma implanted for the first time in the lumbosacral area showing bone invasion, PIK3CA, and PTEN mutations that will facilitate preclinical studies.

Patient-Derived Tumor Xenograft Models: Toward the Establishment of Precision Cancer Medicine

Patient-derived xenografts (PDXs) describe models involving the implantation of patient-derived tumor tissue into immunodeficient mice. Compared with conventional preclinical models involving the implantation of cancer cell lines into mice, PDXs can be characterized by the preservation of tumor heterogeneity, and the tumor microenvironment (including stroma/vasculature) more closely resembles that in patients. Consequently, the use of PDX models has improved the predictability of clinical therapeutic responses to 80% or greater, compared with approximately 5% for existing models. In the future, molecular biological analyses, omics analyses, and other experiments will be conducted using recently prepared PDX models under the strong expectation that the analysis of cancer pathophysiology, stem cells, and novel treatment targets and biomarkers will be improved, thereby promoting drug development. This review outlines the methods for preparing PDX models, advances in cancer research using PDX mice, and perspectives for the establishment of precision cancer medicine within the framework of personalized cancer medicine.

Differential Monocyte Actuation in a Three-Organ Functional Innate Immune System-on-a-Chip

A functional, human, multiorgan, pumpless, immune system-on-a-chip featuring recirculating THP-1 immune cells with cardiomyocytes, skeletal muscle, and liver in separate compartments in a serum-free medium is developed. This in vitro platform can emulate both a targeted immune response to tissue-specific damage, and holistic proinflammatory immune response to proinflammatory compound exposure. The targeted response features fluorescently labeled THP-1 monocytes selectively infiltrating into an amiodarone-damaged cardiac module and changes in contractile force measurements without immune-activated damage to the other organ modules. In contrast to the targeted immune response, general proinflammatory treatment of immune human-on-a-chip systems with lipopolysaccharide (LPS) and interferon-γ (IFN-γ) causes nonselective damage to cells in all three-organ compartments. Biomarker analysis indicates upregulation of the proinflammation cytokines TNF-α, IL-6, IL-10, MIP-1, MCP-1, and RANTES in response to LPS + IFN-γ treatment indicative of the M1 macrophage phenotype, whereas amiodarone treatment only leads to an increase in the restorative cytokine IL-6 which is a marker for the M2 phenotype. This system can be used as an alternative to humanized animal models to determine direct immunological effects of biological therapeutics including monoclonal antibodies, vaccines, and gene therapies, and the indirect effects caused by cytokine release from target tissues in response to a drug's pharmacokinetics (PK)/pharmacodynamics (PD) profile.

Novel mitochondrial and cytosolic purification pipeline for compartment-specific metabolomics in mammalian disease model tissues

INTRODUCTION

Mitochondria represent an important milieu for studying the pathogenesis of several major diseases. The need for organelle-level metabolic resolution exists, as mitochondrial/cytosolic metabolites are often diluted beyond detection limits in complex samples. Compartment-specific studies are still hindered by the lack of efficient, cost-effective fractioning methods-applicable to laboratories of all financial/analytical standing.

OBJECTIVES

We established a novel mitochondrial/cytosolic purification pipeline for complimentary GC-TOF-MS and ¹H-NMR metabolomics using robust, commercially available fractionation strategies.

METHODS

Magnetic based mitochondria isolation kits (MACS) were adapted for this purpose, accompanied by cytosolic filtering. Yield was assessed through the percentage recovery of citrate synthase (CS; a mitochondrial marker), purity by immunoblotting against compartment-specific proteins and integrity interrogated through the respiratory coupling ratio (RCR). The effects of the kit-based buffers on MS/NMR analyses of pure metabolite standards were evaluated. Finally, biological applicability to mammalian disease models was shown using Ndufs4 mouse brain tissue.

RESULTS

With minor modifications, MACS produced around 60% more mitochondria compared to a differential centrifugation method. Less than 15% of lysosomal LAMP-2 protein was found in the MACS isolates, confirming relative purity-while RCR's above 6 indicate sufficient mitochondrial integrity. The filtering approach effectively depleted mitochondria from the cytosolic fraction, as indicated by negligible Hsp60 and CS levels. Our GC-MS pilot yielded 60-70 features per fraction, while NMR analyses could quantify 6-10 of the most abundant compounds in each fraction.

CONCLUSION

This study provides a simple and flexible solution for mitochondrial and cytosolic metabolomics in animal model tissues, towards large-scale application of such methodologies in disease research.

Integrating Systems Biology and an Ex Vivo Human Tumor Model Elucidates PD-1 Blockade Response Dynamics

Ex vivo human tumor models have emerged as promising, yet complex tools to study cancer immunotherapy response dynamics. Here, we present a strategy that integrates empirical data from an ex vivo human system with computational models to interpret the response dynamics of a clinically prescribed PD-1 inhibitor, nivolumab, in head and neck squamous cell carcinoma (HNSCC) biopsies (N = 50). Using biological assays, we show that drug-induced variance stratifies samples by T helper type 1 (Th1)-related pathways. We then built a systems biology network and mathematical framework of local and global sensitivity analyses to simulate and estimate antitumor phenotypes, which implicate a dynamic role for the induction of Th1-related cytokines and T cell proliferation patterns. Together, we describe a multi-disciplinary strategy to analyze and interpret the response dynamics of PD-1 blockade using heterogeneous ex vivo data and in silico simulations, which could provide researchers a powerful toolset to interrogate immune checkpoint inhibitors.

Best Practices for Preclinical In Vivo Testing of Cancer Nanomedicines

Significant advances have been made in the development of nanoparticles for cancer treatment in recent years. Despite promising results in preclinical animal models, cancer nanomedicines often fail in clinical trials. This failure rate could be reduced by defining stringent criteria for testing and quality control during the design and development stages, and by performing carefully planned preclinical studies in relevant animal models. This article discusses best practices for the evaluation of nanomedicines in murine tumor models. First, a recommended set of experiments to perform is introduced, including discussion of the types of data to collect during these studies. This is followed by an outline of various tumor models and their clinical relevance. Next, different routes of nanoparticle administration are overviewed, followed by a summary of important controls to include in in vivo studies of nanomedicine. Finally, animal welfare considerations are discussed, and an overview of the steps involved in achieving US Food and Drug Administration approval after animal studies are completed is provided. Researchers should use this report as a guideline for effective preclinical evaluation of cancer nanomedicine. As the community adopts best practices for in vivo testing, the rate of clinical translation of cancer nanomedicines is likely to improve.

The Biology of Malignant Mesothelioma and the Relevance of Preclinical Models

Malignant mesothelioma (MM), especially its more frequent form, malignant pleural mesothelioma (MPM), is a devastating thoracic cancer with limited therapeutic options. Recently, clinical trials that used immunotherapy strategies have yielded promising results, but the benefits are restricted to a limited number of patients. To develop new therapeutic strategies and define predictors of treatment response to existing therapy, better knowledge of the cellular and molecular mechanisms of MM tumors and sound preclinical models are needed. This review aims to provide an overview of our present knowledge and issues on both subjects. MM shows a complex pattern of molecular changes, including genetic, chromosomic, and epigenetic alterations. MM is also a heterogeneous cancer. The recently described molecular classifications for MPM could better consider inter-tumor heterogeneity, while histo-molecular gradients are an interesting way to consider both intra- and inter-tumor heterogeneities. Classical preclinical models are based on use of MM cell lines in culture or implanted in rodents, i.e., xenografts in immunosuppressed mice or isografts in syngeneic rodents to assess the anti-tumor immune response. Recent developments are tumoroids, patient-derived xenografts (PDX), xenografts in humanized mice, and genetically modified mice (GEM) that carry mutations identified in human MM tumor cells. Multicellular tumor spheroids are an interesting in vitro model to reduce animal experimentation; they are more accessible than tumoroids. They could be relevant, especially if they are co-cultured with stromal and immune cells to partially reproduce the human microenvironment. Even if preclinical models have allowed for major advances, they show several limitations: (i) the anatomical and biological tumor microenvironments are incompletely reproduced; (ii) the intra-tumor heterogeneity and immunological contexts are not fully reconstructed; and (iii) the inter-tumor heterogeneity is insufficiently considered. Given that these limitations vary according to the models, preclinical models must be carefully selected depending on the objectives of the experiments. New approaches, such as organ-on-a-chip technologies or in silico biological systems, should be explored in MM research. More pertinent cell models, based on our knowledge on mesothelial carcinogenesis and considering MM heterogeneity, need to be developed. These endeavors are mandatory to implement efficient precision medicine for MM.

Patient-derived xenograft (PDX) models: characteristics and points to consider for the process of establishment

Tumor research has largely relied on xenograft models created by the engraftment of cultured cell lines derived from tumor tissues into immunodeficient mice for in vivo studies. Like in vitro models, such models retain the ability of tumor cells to continuously proliferate, so they have been used to predict the clinical relevance of studies on proliferating cells. However, these models are composed of a limited population of tumor cells, which include only those tumor cells that are able to adapt to culture conditions, and thus they do not reflect the diversity and heterogeneity of tumors. This, at least in part, explains the poor predictivity of non-clinical data in the research and development of molecularly targeted drugs. Recently, research focus has been directed towards patient-derived xenograft (PDX) models created by directly engrafting tumor tissues, which have not been cultured in vitro, into immunodeficient mice. PDX models reflect the diversity and heterogeneity of tumors, and the evidence they provide can be verified in the patient tissues from which they were derived originally. PDX models are anticipated to efficiently bridge non-clinical and clinical data in translational research. Based on the evidence obtained from our research experience, this review describes the characteristics of PDX models for acting as tumor models, and elucidates the points to consider when attempting to establish these models.

Recent Advances in Microfluidic Platforms Applied in Cancer Metastasis: Circulating Tumor Cells' (CTCs) Isolation and Tumor-On-A-Chip

Cancer remains the leading cause of death worldwide despite the enormous efforts that are made in the development of cancer biology and anticancer therapeutic treatment. Furthermore, recent studies in oncology have focused on the complex cancer metastatic process as metastatic disease contributes to more than 90% of tumor-related death. In the metastatic process, isolation and analysis of circulating tumor cells (CTCs) play a vital role in diagnosis and prognosis of cancer patients at an early stage. To obtain relevant information on cancer metastasis and progression from CTCs, reliable approaches are required for CTC detection and isolation. Additionally, experimental platforms mimicking the tumor microenvironment in vitro give a better understanding of the metastatic microenvironment and antimetastatic drugs' screening. With the advancement of microfabrication and rapid prototyping, microfluidic techniques are now increasingly being exploited to study cancer metastasis as they allow precise control of fluids in small volume and rapid sample processing at relatively low cost and with high sensitivity. Recent advancements in microfluidic platforms utilized in various methods for CTCs' isolation and tumor models recapitulating the metastatic microenvironment (tumor-on-a-chip) are comprehensively reviewed. Future perspectives on microfluidics for cancer metastasis are proposed.

Choosing The Right Animal Model for Renal Cancer Research

The increase in the life expectancy of patients with renal cell carcinoma (RCC) in the last decade is due to changes that have occurred in the area of preclinical studies. Understanding cancer pathophysiology and the emergence of new therapeutic options, including immunotherapy, would not be possible without proper research. Before new approaches to disease treatment are developed and introduced into clinical practice they must be preceded by preclinical tests, in which animal studies play a significant role. This review describes the progress in animal model development in kidney cancer research starting from the oldest syngeneic or chemically-induced models, through genetically modified mice, finally to xenograft, especially patient-derived, avatar and humanized mouse models. As there are a number of subtypes of RCC, our aim is to help to choose the right animal model for a particular kidney cancer subtype. The data on genetic backgrounds, biochemical parameters, histology, different stages of carcinogenesis and metastasis in various animal models of RCC as well as their translational relevance are summarized. Moreover, we shed some light on imaging methods, which can help define tumor microstructure, assist in the analysis of its metabolic changes and track metastasis development.

Methods for Evaluation of a Snake Venom-Derived Disintegrin in Animal Models of Human Cancer

Integrin targeting has been shown to be an effective approach for anticancer therapy. We engineered a recombinant disintegrin, vicrostatin (VCN), that binds with high affinity and specificity to the Arg-Gly-Asp (RGD) class of integrins, including αvβ3, αvβ5, and α5β1, involved in tumor invasion and metastasis. We used three different delivery modalities to examine anticancer activity of VCN in mouse models of human ovarian cancer, glioma, and prostate cancer. A female mouse model was used to examine the treatment of established ovarian cancer (OC) using VCN delivered intraperitoneally (IP) weekly either in saline or impregnated in a viscoelastic gel. SKOV3^luc cells (a human OC cell line) were directly injected IP into immunodeficient mice. We also examined the antitumor activity of radioiodinated VCN delivered intravenously in a human glioma model in nude mice. We evaluated the effectiveness of ¹³¹I-VCN in combination with the DNA alkylating agent temozolomide in limiting glioma growth. Finally, treatment of a bone metastatic model of human prostate cancer (PC) in immunodeficient mice was examined using a liposomal formulation of VCN (LVCN) delivered intravenously. Human PC cells were suspended in a solution of Matrigel and injected into the left tibia of immunodeficient mice. Diameters of both the left and right (control) tibias were measured by caliper repeatedly after VCN treatment was initiated.

Simulation-based design and characterization of a microwave applicator for MR-guided hyperthermia experimental studies in small animals

Purpose

The objective of this study was to design and characterize a 2.45 GHz microwave hyperthermia applicator for delivering hyperthermia in experimental small animals to 2 - 4 mm diameter targets located 1 - 3 mm from the skin surface, with minimal heating of the surrounding tissue, under 14.1 T MRI real-time monitoring and feedback control.

Materials and methods

An experimentally validated 3D computational model was employed to design and characterize a non-invasive directional water-cooled microwave hyperthermia applicator. We assessed the effects of: reflector geometry, monopole shape, cooling water temperature, and flow rate on spatial-temperature profiles. The system was integrated with real-time MR thermometry and feedback control to monitor and maintain temperature elevations in the range of 4 - 5 °C at 1 - 3 mm from the applicator surface. The quality of heating was quantified by determining the fraction of the target volume heated to the desired temperature, and the extent of heating in non-targeted regions.

Results

Model-predicted hyperthermic profiles were in good agreement with experimental measurements (Dice Similarity Coefficient of 0.95 - 0.99). Among the four considered criteria, a reflector aperture angle of 120 °, S-shaped monopole antenna with 0.6 mm displacement, and coolant flow rate of 150 ml/min were selected as the end result of the applicator design. The temperature of circulating water and input power were identified as free variables, allowing considerable flexibility in heating target sizes within varying distances from the applicator surface. 2 - 4 mm diameter targets positioned 1 - 3 mm from the applicator surface were heated to hyperthermic temperatures, with target coverage ratio ranging between 76 - 93 % and 11 - 26 % of non-targeted tissue heated.

Conclusion

We have designed an experimental platform for MR-guided hyperthermia, incorporating a microwave applicator integrated with temperature-based feedback control to heat deep-seated targets for experimental studies in small animals.

Cancer Modeling-on-a-Chip with Future Artificial Intelligence Integration

Cancer is one of the leading causes of death worldwide, despite the large efforts to improve the understanding of cancer biology and development of treatments. The attempts to improve cancer treatment are limited by the complexity of the local milieu in which cancer cells exist. The tumor microenvironment (TME) consists of a diverse population of tumor cells and stromal cells with immune constituents, microvasculature, extracellular matrix components, and gradients of oxygen, nutrients, and growth factors. The TME is not recapitulated in traditional models used in cancer investigation, limiting the translation of preliminary findings to clinical practice. Advances in 3D cell culture, tissue engineering, and microfluidics have led to the development of "cancer-on-a-chip" platforms that expand the ability to model the TME in vitro and allow for high-throughput analysis. The advances in the development of cancer-on-a-chip platforms, implications for drug development, challenges to leveraging this technology for improved cancer treatment, and future integration with artificial intelligence for improved predictive drug screening models are discussed.

Insights into the success and failure of systemic therapy for hepatocellular carcinoma

Systemic treatment for hepatocellular carcinoma (HCC) has been boosted by the incorporation of new agents after many negative phase III trials in the decade since the approval of sorafenib. Sorafenib introduced the concept that targeting specific hallmarks of hepatocarcinogenesis could modify the dismal prognosis of this disease, with the drug remaining a cornerstone in the upfront therapy for advanced HCC. The design of clinical trials in this malignancy is complicated by important obstacles related to patient selection, prognostic assessment and the need for endpoints that correlate with improvement in survival outcomes. In addition, the currently used criteria to determine treatment response or progression might prevent physicians from making appropriate clinical judgements and interpreting evidence arising from trials. In this Review, we discuss the advances in systemic therapy for HCC and critically review trial designs in HCC. Although novel therapies, such as new targeted agents and immunotherapies, are being rapidly incorporated, it is paramount to design future clinical trials based on the lessons learned from past failures and successes.

Inappropriate modeling of chronic and complex disorders: How to reconsider the approach in the context of predictive, preventive and personalized medicine, and translational medicine

Preclinical investigations such as animal modeling make the basis of clinical investigations and subsequently patient care. Predictive, preventive, and personalized medicine (PPPM) not only highlights a patient-tailored approach by choosing the right medication, the right dose at the right time point but it as well essentially requires early identification, by the means of complex and state-of-the-art technologies of unmanifested pathological processes in an individual, in order to deliver targeted prevention early enough to reverse manifestation of a pathology. Such an approach can be achieved by taking into account clinical, pathological, environmental, and psychosocial characteristics of the patients or an individual who has a suboptimal health condition. Inappropriate modeling of chronic and complex disorders, in this context, may diminish the predictive potential and slow down the development of PPPM and consequently modern healthcare. Therefore, it is the common goal of PPPM and translational medicine to find the solution for the problem we present in our review. Both, translational medicine and PPPM in parallel, essentially need accurate surrogates for misleading animal models. This study was therefore undertaken to provide shreds of evidence against the validity of animal models. Limitations of current animal models and drug development strategies based on animal modeling have been systematically discussed. Finally, a variety of potential surrogates have been suggested to change the unfavorable situation in medical research and consequently in healthcare.

In-air production of 3D co-culture tumor spheroid hydrogels for expedited drug screening

Three-dimensional (3D) in vitro tumor spheroids are becoming popular as pre-clinical platforms for testing the performance of existing drugs or for discovery of innovative anti-cancer therapeutics. This focus is correlated with in vitro 3D tumor models ability to mimic the multicellular compact structure and spatial architecture of human solid tumors. However, these microphysiological systems generally lack the pre-existence of tumor-ECM, a critical aspect that can affect the overall therapeutic performance and the decision of advancing candidate drugs to later stages of the pipeline. Aiming to face this drawback and mimic tumors-ECM, herein we rapidly fabricated in-air hyaluronan-methacrylate (HA-MA) and gelatin-methacrylate (GelMA) photocrosslinkable 3D spheroid microgels by using superhydrophobic surfaces. These platforms were used for establishing heterotypic 3D co-culture models of prostate cancer cells (PC-3) and human osteoblasts (hOB) to mimic prostate cancer-to-bone metastasis cellular heterogeneity and the tumor-ECM microenvironment. 3D microgel microtumors morphology, size and cell number were easily controlled via digital droplet generation on polystyrene superhydrophobic surfaces and under solvent-free conditions when compared to microfluidics or electrospray. Co-culture 3D microgels formed by 2.5%HA-MA-5%GelMA and 5%HA-MA-5%GelMA ratios showed the highest calcium deposition after 14 days of culture, evidencing osteoblasts viability and the establishment of functional mineralization in the 3D hydrogel matrix. Cisplatin cytotoxicity evaluation showed that 3D microgels are more resistant to platin chemotherapeutics than single or co-culture 3D multicellular spheroid counterparts. Overall, our findings indicate that solvent-free, in-air produced 3D microgel microenvironments are cost-effective and robust tumor mimicking platforms for in vitro high-throughput screening of therapeutics targeted to prostate-to-bone metastasis microenvironments. STATEMENT OF SIGNIFICANCE: The generation of robust microphysiological systems that recapitulate the complexity of the metastatic prostate-to-bone tumor microenvironment is crucial for pre-clinical evaluation of new therapeutics that can eradicate these secondary tumors. In this study, we employed superhydrophobic (SH) surfaces to rapidly fabricate photocrosslinkable hyaluronan-methacrylate/gelatin-methacrylate 3D spheroid microgels for prostate cancer cells and human osteoblasts co-culture models that simultaneously mimic the cellular and ECM tumor components. The use of SH platforms overcomes the issues of standard in-liquid microgel production technologies by providing a robust control over 3D microgels size/morphology and cell-cell co-encapsulation numbers, while avoiding the use of oil-based microgel droplets generation. Overall, SH surfaces allowed a solvent-free, cost-effective, reproducible and adaptable fabrication of heterotypic 3D spherical microgels for high throughput drug screening.

Animal models of cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive biliary tract malignancy with a poor overall prognosis. There is a critical need to develop effective targeted therapies for the treatment of this lethal disease. In an effort to address this challenge, preclinical in vivo studies have become paramount in understanding CCA carcinogenesis, progression, and therapy. Various CCA animal models exist including carcinogen-based models in which animals develop CCA after exposure to a carcinogen, genetically engineered mouse models in which genetic changes are induced in mice leading to CCA, murine syngeneic orthotopic models, as well as xenograft tumors derived from xenotransplantation of CCA cells, organoids, and patient-derived tissue. Each type has distinct advantages as well as shortcomings. In the ideal animal model of CCA, the tumor arises from the biliary tract in an immunocompetent host with a species-matched tumor microenvironment. Such a model would also be time-efficient, recapitulate the genetic and histopathological features of human CCA, and predict therapeutic response in humans. Recently developed biliary tract transduction and orthotopic syngeneic transplant mouse models encompass several of these elements. Herein, we review the different animal models of CCA, their advantages and deficiencies, as well as features which mimic human CCA.

Microfluidic devices for embryonic and larval zebrafish studies

Zebrafish or Danio rerio is an established model organism for studying the genetic, neuronal and behavioral bases of diseases and for toxicology and drug screening. The embryonic and larval stages of zebrafish have been used extensively in fundamental and applied research due to advantages offered such as body transparency, small size, low cost of cultivation and high genetic homology with humans. However, the manual experimental methods used for handling and investigating this organism are limited due to their low throughput, labor intensiveness and inaccuracy in delivering external stimuli to the zebrafish while quantifying various neuronal and behavioral responses. Microfluidic and lab-on-a-chip devices have emerged as ideal technologies to overcome these challenges. In this review paper, the current microfluidic approaches for investigation of behavior and neurobiology of zebrafish at embryonic and larval stages will be reviewed. Our focus will be to provide an overview of the microfluidic methods used to manipulate (deliver and orient), immobilize and expose or inject zebrafish embryos or larvae, followed by quantification of their responses in terms of neuron activities and movement. We will also provide our opinion in terms of the direction that the field of zebrafish microfluidics is heading toward in the area of biomedical engineering.

Generation of lung organoids from human pluripotent stem cells in vitro

The lung epithelium is derived from the endodermal germ layer, which undergoes a complex series of endoderm-mesoderm-mediated signaling events to generate the final arborized network of conducting airways (bronchi, bronchioles) and gas-exchanging units (alveoli). These stages include endoderm induction, anterior-posterior and dorsal-ventral patterning, lung specification, lung budding, branching morphogenesis, and, finally, maturation. Here we describe a protocol that recapitulates several of these milestones in order to differentiate human pluripotent stem cells (hPSCs) into ventral-anterior foregut spheroids and further into two distinct types of organoids: human lung organoids and bud tip progenitor organoids. The resulting human lung organoids possess cell types and structures that resemble the bronchi/bronchioles of the developing human airway surrounded by lung mesenchyme and cells expressing alveolar-cell markers. The bud tip progenitor organoids possess a population of highly proliferative multipotent cells with in vitro multilineage differentiation potential and in vivo engraftment potential. Human lung organoids can be generated from hPSCs in 50-85 d, and bud tip progenitor organoids can be generated in 22 d. The two hPSC-derived models presented here have been benchmarked with human fetal tissue and found to be representative of human fetal-like tissue. The bud tip progenitor organoids are thus ideal for exploring epithelial fate decisions, while the human lung organoids can be used to model epithelial-mesenchymal cross-talk during human lung development. In addition to their applications in developmental biology, human lung organoids and bud tip progenitor organoids may be implemented in regenerative medicine, tissue engineering, and pharmaceutical safety and efficacy testing.

Bridging the translational gap: Implementation of multimodal small animal imaging strategies for tumor burden assessment in a co-clinical trial

In designing co-clinical cancer studies, preclinical imaging brings unique challenges that emphasize the gap between man and mouse. Our group is developing quantitative imaging methods for the preclinical arm of a co-clinical trial studying immunotherapy and radiotherapy in a soft tissue sarcoma model. In line with treatment for patients enrolled in the clinical trial SU2C-SARC032, primary mouse sarcomas are imaged with multi-contrast micro-MRI (T1 weighted, T2 weighted, and T1 with contrast) before and after immune checkpoint inhibition and pre-operative radiation therapy. Similar to the patients, after surgery the mice will be screened for lung metastases with micro-CT using respiratory gating. A systems evaluation was undertaken to establish a quantitative baseline for both the MR and micro-CT systems against which others systems might be compared. We have constructed imaging protocols which provide clinically-relevant resolution and contrast in a genetically engineered mouse model of sarcoma. We have employed tools in 3D Slicer for semi-automated segmentation of both MR and micro-CT images to measure tumor volumes efficiently and reliably in a large number of animals. Assessment of tumor burden in the resulting images was precise, repeatable, and reproducible. Furthermore, we have implemented a publicly accessible platform for sharing imaging data collected during the study, as well as protocols, supporting information, and data analyses. In doing so, we aim to improve the clinical relevance of small animal imaging and begin establishing standards for preclinical imaging of tumors from the perspective of a co-clinical trial.

Stromal integrin α11-deficiency reduces interstitial fluid pressure and perturbs collagen structure in triple-negative breast xenograft tumors

Background

Cancer progression is influenced by a pro-tumorigenic microenvironment. The aberrant tumor stroma with increased collagen deposition, contractile fibroblasts and dysfunctional vessels has a major impact on the interstitial fluid pressure (PIF) in most solid tumors. An increased tumor PIF is a barrier to the transport of interstitial fluid into and within the tumor. Therefore, understanding the mechanisms that regulate pressure homeostasis can lead to new insight into breast tumor progression, invasion and response to therapy. The collagen binding integrin α11β1 is upregulated during myofibroblast differentiation and expressed on fibroblasts in the tumor stroma. As a collagen organizer and a probable link between contractile fibroblasts and the complex collagen network in tumors, integrin α11β1 could be a potential regulator of tumor PIF.

Methods

We investigated the effect of stromal integrin α11-deficiency on pressure homeostasis, collagen organization and tumor growth using orthotopic and ectopic triple-negative breast cancer xenografts (MDA-MB-231 and MDA-MB-468) in wild type and integrin α11-deficient mice. PIF was measured by the wick-in-needle technique, collagen by Picrosirius Red staining and electron microscopy, and uptake of radioactively labeled 5FU by microdialysis. Further, PIF in heterospheroids composed of MDA-MB-231 cells and wild type or integrin α11-deficient fibroblasts was measured by micropuncture.

Results

Stromal integrin α11-deficiency decreased PIF in both the orthotopic breast cancer models. A concomitant perturbed collagen structure was seen, with fewer aligned and thinner fibrils. Integrin α11-deficiency also impeded MDA-MB-231 breast tumor growth, but no effect was observed on drug uptake. No effects were seen in the ectopic model. By investigating the isolated effect of integrin α11-positive fibroblasts on MDA-MB-231 cells in vitro, we provide evidence that PIF regulation was mediated by integrin α11-positive fibroblasts.

Conclusion

We hereby show the importance of integrin α11β1 in pressure homeostasis in triple-negative breast tumors, indicating a new role for integrin α11β1 in the tumor microenvironment. Our data suggest that integrin α11β1 has a pro-tumorigenic effect on triple-negative breast cancer growth in vivo. The significance of the local microenvironment is shown by the different effects of integrin α11β1 in the orthotopic and ectopic models, underlining the importance of choosing an appropriate preclinical model.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5449-z) contains supplementary material, which is available to authorized users.

Three-Dimensional Organoids in Cancer Research: The Search for the Holy Grail of Preclinical Cancer Modeling

Most solid tumors become therapy resistant and will relapse, with no durable treatment option available. One major impediment to our understanding of cancer biology and finding innovative approaches to cancer treatment stems from the lack of better preclinical tumor models that address and explain tumor heterogeneity and person-to-person differences in therapeutic and toxic responses. Past cancer research has been driven by inadequate in vitro assays utilizing two-dimensional monolayers of cancer cells and animal models. Additionally, animal models do not truly mimic the original human tumor, are time consuming, and usually costly. New preclinical models are needed for innovation in cancer translational research. Hence, it is time to welcome the three-dimensional (3D) organoids: self-organizing cells grown in 3D culture systems mimicking the parent tissues from which the primary cells originate. The 3D organoids offer deeper insights into the crucial cellular processes in tissue and organ formation and pathological processes. Generation of near-perfect physiological microenvironments allow 3D organoids to couple with gene editing tools, such as the clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated 9 and the transcription activator-like effector nucleases to model human diseases, offering distinct advantages over current models. We explain in this expert review that through recapitulating patients' normal and tumor tissues, organoid technology can markedly advance personalized medicine and help reveal once hidden aspects of cancers. The use of defined tissue- or organ-specific matrices, among other factors, will likely allow organoid technology to realize its potential in innovating many fields of life sciences.

Pediatric Formulations: Knowledge Gaps Limiting the Expedited Preclinical to Clinical Translation in Children

Traditionally, drug discovery and development research have been primarily focused on the mitigation of disease treatment for the general adult population, often overlooking the medical needs of pediatric patients. While remarkable progress toward the discovery of better medicines has been made, the pharmacological differences between children and adults are often neglected as part of the translation process. In fact, until recently, children have been considered therapeutic orphans due to the lack of significant drug discovery, formulation development, and dosage form design specifically tailored for pediatric patients. Perhaps the least understood is the significant physiological changes that occur during the maturation process from birth to adulthood. It requires careful considerations to achieve age-specific-desired therapeutic outcomes with minimal toxicity. This introduces considerable risk into the preclinical and clinical testing of new medicaments, which until recently, was avoided based on the conventional approach where a demonstration of safe and efficacious use in adults over several years potentially would minimize the chance of adverse juvenile responses. However, the lack of appropriate drug products for children has led to off-label use of adult medicines with potential life-threatening adverse reactions and health complications. Recent developments and future considerations regarding pediatric drug discovery and development using a patient-centric approach in the context of ontogenic biopharmaceutical considerations are discussed below.

Resveratrol: Twenty Years of Growth, Development and Controversy

Resveratrol was first isolated in 1939 by Takaoka from Veratrum grandiflorum O. Loes. Following this discovery, sporadic descriptive reports appeared in the literature. However, spurred by our seminal paper published nearly 60 years later, resveratrol became a household word and the subject of extensive investigation. Now, in addition to appearing in over 20,000 research papers, resveratrol has inspired monographs, conferences, symposia, patents, chemical derivatives, etc. In addition, dietary supplements are marketed under various tradenames. Once resveratrol was brought to the limelight, early research tended to focus on pharmacological activities related to the cardiovascular system, inflammation, and cancer but, over the years, the horizon greatly expanded. Around 130 human clinical trials have been (or are being) conducted with varying results. This may be due to factors such as disparate doses (ca. 5 to 5,000 mg/day) and variable experimental settings. Further, molecular targets are numerous and a dominant mechanism is elusive or nonexistent. In this context, the compound is overtly promiscuous. Nonetheless, since the safety profile is pristine, and use as a dietary supplement is prevalent, these features are not viewed as detrimental. Given the ongoing history of resveratrol, it is reasonable to advocate for additional development and further clinical investigation. Topical preparations seem especially promising, as do conditions that can respond to anti-inflammatory action and/or direct exposure, such as colon cancer prevention. Although the ultimate fate of resveratrol remains an open question, thus far, the compound has inspired innovative scientific concepts and enhanced public awareness of preventative health care.

Challenges and Opportunities of Nanotechnology as Delivery Platform for Tocotrienols in Cancer Therapy

Plant-derived phytonutrients have emerged as health enhancers. Tocotrienols from the vitamin E family gained high attention in recent years due to their multi-targeted biological properties, including lipid-lowering, neuroprotection, anti-inflammatory, antioxidant, and anticancer effects. Despite well-defined mechanism of action as an anti-cancer agent, their clinical use is hampered by poor pharmacokinetic profile and low oral bioavailability. Delivery systems based on nanotechnology were proven to be advantageous in elevating the delivery of tocotrienols to tumor sites for enhanced efficacy. To date, preclinical development of nanocarriers for tocotrienols include niosomes, lipid nanoemulsions, nanostructured lipid carriers (NLCs) and polymeric nanoparticles. Active targeting was explored via the use of transferrin as targeting ligand in niosomes. In vitro, nanocarriers were shown to enhance the anti-proliferative efficacy and cellular uptake of tocotrienols in cancer cells. In vivo, improved bioavailability of tocotrienols were reported with NLCs while marked tumor regression was observed with transferrin-targeted niosomes. In this review, the advantages and limitations of each nanocarriers were critically analyzed. Furthermore, a number of key challenges were identified including scale-up production, biological barriers, and toxicity profiles. To overcome these challenges, three research opportunities were highlighted based on rapid advancements in the field of nanomedicine. This review aims to provide a wholesome perspective for tocotrienol nanoformulations in cancer therapy directed toward effective clinical translation.

Zebrafish blastomere screen identifies retinoic acid suppression of MYB in adenoid cystic carcinoma

Pluripotent cells have been used to probe developmental pathways that are involved in genetic diseases and oncogenic events. To find new therapies that would target MYB-driven tumors, we developed a pluripotent zebrafish blastomere culture system. We performed a chemical genetic screen and identified retinoic acid agonists as suppressors of c-myb expression. Retinoic acid treatment also decreased c-myb gene expression in human leukemia cells. Translocations that drive overexpression of the oncogenic transcription factor MYB are molecular hallmarks of adenoid cystic carcinoma (ACC), a malignant salivary gland tumor with no effective therapy. Retinoic acid agonists inhibited tumor growth in vivo in ACC patient-derived xenograft models and decreased MYB binding at translocated enhancers, thereby potentially diminishing the MYB positive feedback loop driving ACC. Our findings establish the zebrafish pluripotent cell culture system as a method to identify modulators of tumor formation, particularly establishing retinoic acid as a potential new effective therapy for ACC.

Applications of tumor chip technology

Over the past six decades the inflation-adjusted cost to bring a new drug to market has been increasing constantly and doubles every 9 years - now reaching in excess of $2.5 billion. Overall, the likelihood of FDA approval for a drug (any disease indication) that has entered phase I clinical trials is a mere 9.6%, with the approval rate for oncology far below average at only 5.1%. Lack of efficacy or toxicity is often not revealed until the later stages of clinical trials, despite promising preclinical data. This indicates that the current in vitro systems for drug screening need to be improved for better predictability of in vivo outcomes. Microphysiological systems (MPS), or bioengineered 3D microfluidic tissue and organ constructs that mimic physiological and pathological processes in vitro, can be leveraged across preclinical research and clinical trial stages to transform drug development and clinical management for a range of diseases. Here we review the current state-of-the-art in 3D tissue-engineering models developed for cancer research, with a focus on tumor-on-a-chip, or tumor chip, models. From our viewpoint, tumor chip systems can advance innovative medicine to ameliorate the high failure rates in anti-cancer drug development and clinical treatment.

Engineered 3D tumour model for study of glioblastoma aggressiveness and drug evaluation on a detachably assembled microfluidic device

3D models of tumours have emerged as an advanced technique in pharmacology and tumour cell biology, in particular for studying malignant tumours such as glioblastoma multiforme (GBM). Herein, we developed a 3D GBM model on a detachably assembled microfluidic device, which could be used to study GBM aggressiveness and for anti-GBM drug testing. Fundamental characteristics of the GBM microenvironment in terms of 3D tissue organisation, extracellular matrices and blood flow were reproduced in vitro by serial manipulations in the integrated microfluidic device, including GBM spheroid self-assembly, embedding in a collagen matrix, and continuous perfusion culture, respectively. We could realize multiple spheroids parallel manipulation, whilst, compartmentalized culture, in a highly flexible manner. This method facilitated investigations into the viability, proliferation, invasiveness and phenotype transition of GBM in a 3D microenvironment and under continuous stimulation by drugs. Anti-invasion effect of resveratrol, a naturally isolated polyphenol, was innovatively evaluated using this in vitro 3D GBM model. Temozolomide and the combination of resveratrol and temozolomide were also evaluated as control. This scalable model enables research into GBM in a more physiologically relevant microenvironment, which renders it promising for use in translational or personalised medicine to examine the impact of, or identify combinations of, therapeutic agents.

Tumor xenograft animal models for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the predominant subtype of esophageal cancer worldwide and highly prevalent in less developed regions. Management of ESCC is challenging and involves multimodal treatments. Patient prognosis is generally poor especially for those diagnosed in advanced disease stage. One factor contributing to this clinical dismal is the incomplete understanding of disease mechanism, for which this situation is further compounded by the presence of other limiting factors for disease diagnosis, patient prognosis and treatments. Tumor xenograft animal models including subcutaneous tumor xenograft model, orthotopic tumor xenograft model and patient-derived tumor xenograft model are vital tools for ESCC research. Establishment of tumor xenograft models involves the implantation of human ESCC cells/xenografts/tissues into immunodeficient animals, in which mice are most commonly used. Different tumor xenograft models have their own advantages and limitations, and these features serve as key factors to determine the use of these models at different stages of research. Apart from their routine use on basic research to understand disease mechanism of ESCC, tumor xenograft models are actively employed for undertaking preclinical drug screening project and biomedical imaging research.

Predictive Value of CD44 in Muscle-Invasive Bladder Cancer and Its Relationship with IL-6 Signaling

BACKGROUND

CD44, a cancer stem cell surface marker, is associated with treatment resistance and prognosis in some cancers. In the present study, we examined the predictive value of CD44 in muscle-invasive bladder cancer (MIBC).

METHODS

We retrospectively analyzed the clinical outcomes of 105 MIBC patients and correlated these outcomes with the expression of CD44. Furthermore, the bladder cancer cell lines HT1197 and MB49 were selected for cellular and animal experiments to investigate the correlation between CD44 and tumor aggressiveness.

RESULTS

Analysis of clinical specimens indicated that CD44 staining was significantly associated with a higher clinical stage, higher locoregional failure rate, and lower disease-specific survival rate for MIBC patients. Using cellular experiments and orthotopic tumor models, we showed that CD44+ bladder cancer cells had a higher invasion ability and augmented epithelial-mesenchymal transition (EMT) compared with CD44 cells. There was a significant correlation between interleukin (IL)-6 and CD44 levels noted by in vitro testing, and clinical samples. Blockade of IL-6 attenuated the expression of CD44, cancer stem-cell-like properties, and aggressive tumor behavior in vitro and in vivo. The related changes included the attenuated STAT3 activation and EMT, and decreased programmed death ligand 1-mediated T-cell suppression.

CONCLUSION

Our findings suggest that CD44 expression is positively associated with tumor aggressiveness in bladder cancer, and activated IL-6 signaling provides a suitable microenvironment for the induction of CD44 expression.

Preclinical, non-genetic models of lung adenocarcinoma: a comparative survey

Lung cancer is the leading cause of cancer-related mortality worldwide. Animal models are key in analyzing cancer biology and therapy evaluation. We here compared relevant non-genetic lung cancer models with regard to tumor induction period, incidence, morbidity and mortality rate and the immunological composition of primary tumors and the occurrence of tertiary lymphoid organs (TLO): (I) intraperitoneal Urethane injection (1g/kg), (II) Lewis lung carcinoma (LLC) cell line model (intravenous or subcutaneous), and (III) ex vivo three-dimensional (3D) primary cell culture model established from subcutaneously developed LLC-induced tumors. The incidence of Urethane induced lung tumors was 100% in both, C57BL/6 and BALB/c strains without morbidity or mortality at twenty weeks after injection. The mean size of tumor nodules after Urethane injection was significantly larger in BALB/c mice vs. C57BL/6 (p<0.01). Three times of Urethane injection produced significantly more tumor nodules in both mouse strains compared to one injection (BALB/c: p<0.01; C57BL/6: p<0.05). TLOs were only found in the Urethane-induced model. Although the cell line models also showed 100% induction rate, morbidity was high due to skin ulceration on the inoculation site and the development of pleural effusions in the subcutaneous model and the intravenous model, respectively. Tendencies, but no significant differences (p>0.05) could be found in the count of CD4⁺, CD8⁺, F4/80⁺ and NKp46⁺ cells in a tumor nodule among investigated models. All discussed models provided a high tumor incidence rate. TLOs were exclusively found in the Urethane-induced model. No significant difference could be found regarding immune cells across models.

Biomimetic models to examine microenvironmental regulation of glioblastoma stem cells

Glioblastoma multiforme (GBM), a malignant brain tumor, is the deadliest form of human cancer with low survival rates because of its highly invasive nature. In recent years, there has been a growing appreciation for the role that glioblastoma stem cells (GSCs) play during tumorigenesis and tumor recurrence of GBM. GSCs are a specialized subset of GBM cells with stem cell-like features that contribute to tumor initiation and therapeutic resistance. Thus, to enhance therapeutic efficiency and improve survival, targeting GSCs and their microenvironmental niche appears to be a promising approach. To develop this approach, understanding GSC-microenvironment interactions is crucial. This review discusses various biomimetic model systems to understand the impact of biophysical, biochemical, and cellular microenvironmental cues on GSC behaviors. These models include two-dimensional or matrix-free environment models, engineered biomaterial-based three-dimensional models, co-culture models, and mouse and rat in vivo models. These systems have been used to study the effects of biophysical factors, modulation of signaling pathways, extracellular matrix components, and culture conditions on the GSC phenotype. The advantages and disadvantages of these model systems and their impact in the field of GSC research are discussed.