Animal models of urinary bladder cancer and their application to novel drug discovery

Current views on in vivo models for breast cancer research and related drug development

INTRODUCTION

Animal models play a crucial role in breast cancer research, in particular mice and rats, who develop mammary tumors that closely resemble their human counterparts. These models allow the study of mechanisms behind breast carcinogenesis, as well as the efficacy and safety of new, and potentially more effective and advantageous therapeutic approaches. Understanding the advantages and disadvantages of each model is crucial to select the most appropriate one for the research purpose.

AREA COVERED

This review provides a concise overview of the animal models available for breast cancer research, discussing the advantages and disadvantages of each one for searching new and more effective approaches to treatments for this type of cancer.

EXPERT OPINION

Rodent models provide valuable information on the genetic alterations of the disease, the tumor microenvironment, and allow the evaluation of the efficacy of chemotherapeutic agents. However, in vivo models have limitations, and one of them is the fact that they do not fully mimic human diseases. Choosing the most suitable model for the study purpose is crucial for the development of new therapeutic agents that provide better care for breast cancer patients.

Zebrafish in Lung Cancer Research

Zebrafish is increasingly used as a model organism for cancer research because of its genetic and physiological similarities to humans. Modeling lung cancer (LC) in zebrafish has received significant attention. This review focuses on the insights gained from using zebrafish in LC research. These insights range from investigating the genetic and molecular mechanisms that contribute to the development and progression of LC to identifying potential drug targets, testing the efficacy and toxicity of new therapies, and applying zebrafish for personalized medicine studies. This review provides a comprehensive overview of the current state of LC research performed using zebrafish, highlights the advantages and limitations of this model organism, and discusses future directions in the field.

MicroRNA-494-3p facilitates the progression of bladder cancer by mediating the KLF9/RGS2 axis

Bladder cancer (BC) is a familiar malignancy with high morbidity and mortality. The effect of treatment is unsatisfactory after the metastasis and invasion of BC. Hence, more studies should be carried out to explore the metastasis of BC. RT-qPCR or/and western blot was conducted to evaluate miR-494-3p, KLF9, and RGS2 expression. Cell proliferation and invasion were estimated by MTT assay and transwell assay, respectively. Cell migration was tested by wound healing assay and transwell assay. Dual-luciferase reporter gene assay was employed to validate the interplay between miR-494-3p and KLF9 mRNA. The interaction between KLF9 and RGS2 promoter was verified using dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay. miR-494-3p expression was upregulated, whereas KLF9 and RGS2 were downregulated in BC cells. miR-494-3p inhibition was competent to limit the growth of BC cells. KLF9 knockdown abolished the miR-494-3p depletion-mediated inhibitory growth of BC cells. Mechanistically, we found that KLF9 was a downstream gene of miR-494-3p and could bind to the promoter region of RGS2 to promote the expression of RGS2. Moreover, RGS2 knockdown abrogated the suppressive effects of miR-494-3p knockdown on the proliferation, migration, and invasion of BC cells. Notably, miR-494-3p inhibition obstructed the tumor growth in nude mice. miR-494-3p silencing inhibited the progression of BC by regulating the KLF9/RGS2 axis in vitro and in vivo, which laid the foundation for experiments of miR-494-3p in BC and provided therapeutic targets for BC.

Establishment of 2.5D organoid culture model using 3D bladder cancer organoid culture

Three-dimensional (3D) organoid culture holds great promises in cancer precision medicine. However, Matrigel and stem cell-stimulating supplements are necessary for culturing 3D organoid cells. It costs a lot of money and consumes more time and effort compared with 2D cultured cells. Therefore, the establishment of cheaper and Matrigel-free organoid culture that can maintain the characteristics of a part of 3D organoids is demanded. In the previous study, we established a dog bladder cancer (BC) 3D organoid culture system by using their urine samples. Here, we successfully isolated cells named "2.5D organoid" from multiple strains of dog BC 3D organoids using 2.5 organoid media. The cell proliferation speed of 2.5D organoids was faster than parental 3D organoid cells. The expression pattern of stem cell markers was close to 3D organoids. Injection of 2.5D organoid cells into immunodeficient mice formed tumors and showed the histopathological characteristics of urothelial carcinoma similar to the injection of dog BC 3D organoids. The 2.5D organoids had a similar sensitivity profile for anti-cancer drug treatment to their parental 3D organoids. These data suggest that our established 2.5D organoid culture method might become a reasonable and useful tool instead of 3D organoids in dog BC research and therapy.

Conditional reprogramming: Modeling urological cancer and translation to clinics

Patient-derived models, including cell models (organoids and conditionally reprogrammed cells [CRCs]) and patient-derived xenografts, are urgently needed for both basic and translational cancer research. Conditional reprogramming (CR) technique refers to a co-culture system of primary human normal or tumor cells with irradiated murine fibroblasts in the presence of a Rho-associated kinase inhibitor to allow the primary cells to acquire stem cell properties and the ability to proliferate indefinitely in vitro without any exogenous gene or viral transfection. Considering its robust features, the CR technique may facilitate cancer research in many aspects. Under in vitro culturing, malignant CRCs can share certain genetic aberrations and tumor phenotypes with their parental specimens. Thus, tumor CRCs can promisingly be utilized for the study of cancer biology, the discovery of novel therapies, and the promotion of precision medicine. For normal CRCs, the characteristics of normal karyotype maintenance and lineage commitment suggest their potential in toxicity testing and regenerative medicine. In this review, we discuss the applications, limitations, and future potential of CRCs in modeling urological cancer and translation to clinics.

Porcine cancer models: potential tools to enhance cancer drug trials

INTRODUCTION

The amount of time and money invested into cancer drug research, development, and clinical trials has continually increased over the past few decades. Despite record high cancer drug approval rates, cancer remains a leading cause of death. This suggests the need for more effective tools to help bring novel therapies to clinical practice in a timely manner.

AREAS COVERED

In this review, current issues associated with clinical trials are discussed, specifically focusing on poor accrual rates and time for trial completion. In addition, details regarding preclinical studies required before advancing to clinical trials are discussed, including advantages and limitations of current preclinical animal cancer models and their relevance to human cancer trials. Finally, new translational porcine cancer models (Oncopig Cancer Model (OCM)) are presented as potential co-clinical trial models.

EXPERT OPINION

In order to address issues impacting the poor success rate of oncology clinical trials, we propose the incorporation of the transformative OCM 'co-clinical trial' pathway into the cancer drug approval process. Due to the Oncopig's high homology to humans and similar tumor phenotypes, their utilization can provide improved preclinical prediction of both drug safety and efficacy prior to investing significant time and money in human clinical trials.

The N-butyl-N-4-hydroxybutyl Nitrosamine Mouse Urinary Bladder Cancer Model

Urinary bladder cancer (UBC) is a common and complex malignancy, with a multifactorial etiology, like environmental factors, such as cigarette smoking, occupational exposure, and genetic factors.UBC exhibits considerable genotypic and phenotypic heterogeneity. Among all UBC lesions, urothelial carcinoma is the most frequently observed histological type. Despite all the developments made in urologic oncology field, therapeutic options remain inadequate. There is urgency for the identification and development of new antineoplastic drugs to replace or improve current protocols and in vivo models have been proven to be essential for this step. There are different animal models of UBC: Spontaneous and experimentally induced models (genetically engineered, transplantable-xenograft and syngeneic animals- and chemically induced models). N-butyl-N(4-hydroxybutil)nitrosamine (BBN) is the most suitable reagent to generate chemically induced in vivo models of UBC and to study bladder carcinogenesis. BBN has proven, over the years, to be very realistic and reliable. It is bladder specific, and induces high tumor incidence.

Tissue-engineered human 3D model of bladder cancer for invasion study and drug discovery

The tumour microenvironment is critical to both the initiation and maintenance of tumorigenesis. Reconstitution of the microenvironment is a major challenge for in vitro cancer models. Indeed, conventional 2D culture systems cannot replicate the complexity, diversity and dynamic nature of the tumour microenvironment. In this study, we have developed a 3D endotheliazed vesical equivalent by using tissue engineering from primary human cells in which non-invasive or invasive bladder cancer (BCa) cell lines, cultured as compact spheroids, were incorporated. Invasive BCa cells cross the basement membrane and invade the stromal compartment whereas non-invasive BCa cells are confined to the urothelium. Our 3D BCa model could be used as a reliable model for assessing drug responses, potentially reducing or partially replacing animal experiments, and thus should have applications in the identification of novel targets as well as toxicological evaluation of anti-cancer therapies.

Altered expression of CKs 14/20 is an early event in a rat model of multistep bladder carcinogenesis

Cytokeratins (CKs) 14 and 20 are promising markers for diagnosing urothelial lesions and for studying their prognosis and histogenesis. This work aimed to study the immunohistochemical staining patterns of CK14/20 during multistep carcinogenesis leading to papillary bladder cancer in a rat model. Thirty female Fischer 344 rats were divided into three groups: group 1 (control); group 2, which received N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 20 weeks plus 1 week without treatment; and group 3, which received BBN for 20 weeks plus 8 weeks without treatment. Bladder lesions were classified histologically. CK14 and CK20 immunostaining was assessed according to its distribution and intensity. In control animals, 0-25% of basal cells and umbrella cells stained positive for CK14 and CK20 respectively. On groups 2 and 3, nodular hyperplastic lesions showed normal CK20 and moderately increased CK14 staining (26-50% of cells). Dysplasia, squamous metaplasia, papilloma, papillary tumours of low malignant potential and low- and high-grade papillary carcinomas showed increased CK14 and CK20 immunostaining in all epithelial layers. Altered CK14 and CK20 expression is an early event in urothelial carcinogenesis and is present in a wide spectrum of urothelial superficial neoplastic and preneoplastic lesions.

Canine urothelial carcinoma: genomically aberrant and comparatively relevant

Urothelial carcinoma (UC), also referred to as transitional cell carcinoma (TCC), is the most common bladder malignancy in both human and canine populations. In human UC, numerous studies have demonstrated the prevalence of chromosomal imbalances. Although the histopathology of the disease is similar in both species, studies evaluating the genomic profile of canine UC are lacking, limiting the discovery of key comparative molecular markers associated with driving UC pathogenesis. In the present study, we evaluated 31 primary canine UC biopsies by oligonucleotide array comparative genomic hybridization (oaCGH). Results highlighted the presence of three highly recurrent numerical aberrations: gain of dog chromosome (CFA) 13 and 36 and loss of CFA 19. Regional gains of CFA 13 and 36 were present in 97 % and 84 % of cases, respectively, and losses on CFA 19 were present in 77 % of cases. Fluorescence in situ hybridization (FISH), using targeted bacterial artificial chromosome (BAC) clones and custom Agilent SureFISH probes, was performed to detect and quantify these regions in paraffin-embedded biopsy sections and urine-derived urothelial cells. The data indicate that these three aberrations are potentially diagnostic of UC. Comparison of our canine oaCGH data with that of 285 human cases identified a series of shared copy number aberrations. Using an informatics approach to interrogate the frequency of copy number aberrations across both species, we identified those that had the highest joint probability of association with UC. The most significant joint region contained the gene PABPC1, which should be considered further for its role in UC progression. In addition, cross-species filtering of genome-wide copy number data highlighted several genes as high-profile candidates for further analysis, including CDKN2A, S100A8/9, and LRP1B. We propose that these common aberrations are indicative of an evolutionarily conserved mechanism of pathogenesis and harbor genes key to urothelial neoplasia, warranting investigation for diagnostic, prognostic, and therapeutic applications.