Insights from animal models of bladder cancer: recent advances, challenges, and opportunities

Assessment of Tumor-Associated Tissue Eosinophilia (TATE) and Tumor-Associated Macrophages (TAMs) in Canine Transitional Cell Carcinoma of the Urinary Bladder

Transitional cell carcinoma of the urinary bladder is a significant neoplasm in dogs, characterized by a poor prognosis and a high metastatic potential. These canine spontaneous tumors share many characteristics with human transitional cell carcinoma, making them an excellent comparative model. The role of inflammatory infiltration in tumor development and progression is frequently contradictory, especially concerning tumor-associated tissue eosinophils (TATE) and tumor-associated macrophages (TAMs). This study aims to analyze TATE and TAMs in canine transitional cell carcinoma of the urinary bladder. Congo Red staining was used to identify TATE, and immunohistochemistry was performed to detect TAMs in 34 cases of canine transitional cell carcinoma of the bladder carcinomas, categorized into low and high grades. Statistically significant differences were observed between the number of eosinophils and macrophages in the two groups of tumors. The number of TATE was higher in low-grade malignant tumors, but the number of TAMs was higher in high-grade tumors. Our findings suggest the importance of TATEs and TAMs in the aggressiveness of canine transitional cell carcinoma and propose their potential use as therapeutic targets.

Evaluation of the safety and feasibility of electrochemotherapy with intravenous bleomycin as local treatment of bladder cancer in dogs

Local treatment of canine urothelial carcinoma (UC) of the bladder is a challenge. More than 90% of the cases invade the muscular layer, more than 50% develop on bladder sites with a difficult surgical approach and often requiring radical surgical procedures. This study aims to evaluate the safety and feasibility of electrochemotherapy (ECT) with intravenous bleomycin (BLM) as a local therapy for bladder UC. This prospective study included 21 dogs with spontaneous bladder UC. Regional/distant metastases and neoplastic infiltration of the serosa was considered the main exclusion criteria. We had no deaths during ECT or in the immediate postoperative period, and no suture dehiscence. Most dogs (19/21) developed mild adverse effects, whereas two dogs developed ureteral stenosis. Complete response (CR) was achieved in 62% of the cases (13/21), while partial response (PR) was achieved in 24% (5/21). The median survival and disease-free survival times were 284 and 270 days, respectively. Overall survival was significantly better in the dogs who achieved a CR. In conclusion, ECT was well-tolerated in dogs with UC, demonstrating its safety and feasibility. These data pave the way for new studies aimed at evaluating the effectiveness of ECT in canine bladder UC as a translational model for human disease.

Metformin-Loaded Chitosan Hydrogels Suppress Bladder Tumor Growth in an Orthotopic Mouse Model via Intravesical Administration

Our previous study found that the intravesical perfusion of metformin has excellent inhibitory effects against bladder cancer (BC). However, this administration route allows the drug to be diluted and excreted in urine. Therefore, increasing the adhesion of metformin to the bladder mucosal layer may prolong the retention time and increase the pharmacological activity. It is well known that chitosan (Cs) has a strong adhesion to the bladder mucosal layer. Thus, this study established a novel formulation of metformin to enhance its antitumor activity by extending its retention time. In this research, we prepared Cs freeze-dried powder and investigated the effect of metformin-loaded chitosan hydrogels (MLCH) in vitro and in vivo. The results showed that MLCH had a strong inhibitory effect against proliferation and colony formation in vitro. The reduction in BC weight and the expression of tumor biomarkers in orthotopic mice showed the robust antitumor activity of MLCH via intravesical administration in vivo. The non-toxic profile of MLCH was observed as well, using histological examinations. Mechanistically, MLCH showed stronger functional activation of the AMPKα/mTOR signaling pathway compared with metformin alone. These findings aim to make this novel formulation an efficient candidate for managing BC via intravesical administration.

Effects of Scaffolds on Urine- and Urothelial Carcinoma Tissue-Derived Organoids from Bladder Cancer Patients

Organoids are three-dimensional constructs generated by placing cells in scaffolds to facilitate the growth of cultures with cell-cell and cell-matrix interactions close to the in vivo situation. Organoids may contain different types of cells, including cancer cells, progenitor cells, or differentiated cells. As distinct culture conditions have significant effects on cell metabolism, we explored the expansion of cells and expression of marker genes in bladder cancer cells expanded in two different common scaffolds. The cells were seeded in basement membrane extract (BME; s.c., Matrigel®) or in a cellulose-derived hydrogel (GrowDex®, GD) and cultured. The size of organoids and expression of marker genes were studied. We discovered that BME facilitated the growth of significantly larger organoids of cancer cell line RT112 (p < 0.05), cells from a solid tumor (p < 0.001), and a voiding urine sample (p < 0.001). Expression of proliferation marker Ki76, transcription factor TP63, cytokeratin CK20, and cell surface marker CD24 clearly differed in these different tumor cells upon expansion in BME when compared to cells in GD. We conclude that the choice of scaffold utilized for the generation of organoids has an impact not only on cell growth and organoid size but also on protein expression. The disadvantages of batch-to-batch-variations of BME must be balanced with the phenotypic bias observed with GD scaffolds when standardizing organoid cultures for clinical diagnoses.

Non-Invasive Imaging Modalities in Intravesical Murine Models of Bladder Cancer

Bladder cancer (BCa) is the sixth most prevalent cancer in men and seventeenth most prevalent cancer in women worldwide. Current treatment paradigms have limited therapeutic impact, suggesting an urgent need for the investigation of novel therapies. To best emulate the progression of human BCa, a pre-clinical intravesical murine model is required in conjunction with existing non-invasive imaging modalities to detect and evaluate cancer progression. Non-invasive imaging modalities reduce the number of required experimental models while allowing for longitudinal studies of novel therapies to investigate long-term efficacy. In this review, we discuss the individual and multi-modal use of non-invasive imaging modalities; bioluminescence imaging (BLI), micro-ultrasound imaging (MUI), magnetic resonance imaging (MRI), and positron emission tomography (PET) in BCa evaluation. We also provide an update on the potential and the future directions of imaging modalities in relation to intravesical murine models of BCa.

Phenolic Extract from Extra Virgin Olive Oil Induces Different Anti-Proliferative Pathways in Human Bladder Cancer Cell Lines

Regular consumption of olive oil is associated with protection against chronic-degenerative diseases, such as cancer. Epidemiological evidence indicates an inverse association between olive oil intake and bladder cancer risk. Bladder cancer is among the most common forms of cancer; in particular, the transitional cell carcinoma histotype shows aggressive behavior. We investigated the anti-proliferative effects of a phenolic extract prepared from an extra virgin olive oil (EVOOE) on two human bladder cancer cell lines, namely RT112 and J82, representing the progression from low-grade to high-grade tumors, respectively. In RT112, the EVOOE reduced cell viability (IC50 = 240 μg/mL at 24 h), triggering a non-protective form of autophagy, evidenced by the autophagosome formation and the increase in LC-3 lipidation. In J82, EVOOE induced a strong decrease in cell viability after 24 h of treatment (IC50 = 65.8 μg/mL) through rapid and massive apoptosis, assessed by Annexin V positivity and caspase-3 and -9 activation. Moreover, in both bladder cancer cell lines, EVOOE reduced intracellular reactive oxygen species, but this antioxidant effect was not correlated with its anti-proliferative outcomes. Data obtained suggest that the mixture of phenolic compounds in extra virgin olive oil activates different anti-proliferative pathways.

Early diagnosis of bladder cancer by photoacoustic imaging of tumor-targeted gold nanorods

Detection and removal of bladder cancer lesions at an early stage is crucial for preventing tumor relapse and progression. This study aimed to develop a new technological platform for the visualization of small and flat urothelial lesions of high-grade bladder carcinoma in situ (CIS). We found that the integrin α5β1, overexpressed in bladder cancer cell lines, murine orthotopic bladder cancer and human bladder CIS, can be exploited as a receptor for targeted delivery of GNRs functionalized with the cyclic CphgisoDGRG peptide (Iso4). The GNRs@Chit-Iso4 was stable in urine and selectively recognized α5β1 positive neoplastic urothelium, while low frequency ultrasound-assisted shaking of intravesically instilled GNRs@Chit-Iso4 allowed the distribution of nanoparticles across the entire volume of the bladder. Photoacoustic imaging of GNRs@Chit-Iso4 bound to tumor cells allowed for the detection of neoplastic lesions smaller than 0.5 mm that were undetectable by ultrasound imaging and bioluminescence.

Identification of a naturally-occurring canine model for early detection and intervention research in high grade urothelial carcinoma

BACKGROUND

Early detection and intervention research is expected to improve the outcomes for patients with high grade muscle invasive urothelial carcinoma (InvUC). With limited patients in suitable high-risk study cohorts, relevant animal model research is critical. Experimental animal models often fail to adequately represent human cancer. The purpose of this study was to determine the suitability of dogs with high breed-associated risk for naturally-occurring InvUC to serve as relevant models for early detection and intervention research. The feasibility of screening and early intervention, and similarities and differences between canine and human tumors, and early and later canine tumors were determined.

METHODS

STs (n=120) ≥ 6 years old with no outward evidence of urinary disease were screened at 6-month intervals for 3 years with physical exam, ultrasonography, and urinalysis with sediment exam. Cystoscopic biopsy was performed in dogs with positive screening tests. The pathological, clinical, and molecular characteristics of the "early" cancer detected by screening were determined. Transcriptomic signatures were compared between the early tumors and published findings in human InvUC, and to more advanced "later" canine tumors from STs who had the typical presentation of hematuria and urinary dysfunction. An early intervention trial of an oral cyclooxygenase inhibitor, deracoxib, was conducted in dogs with cancer detected through screening.

RESULTS

Biopsy-confirmed bladder cancer was detected in 32 (27%) of 120 STs including InvUC (n=29, three starting as dysplasia), grade 1 noninvasive cancer (n=2), and carcinoma in situ (n=1). Transcriptomic signatures including druggable targets such as EGFR and the PI3K-AKT-mTOR pathway, were very similar between canine and human InvUC, especially within luminal and basal molecular subtypes. Marked transcriptomic differences were noted between early and later canine tumors, particularly within luminal subtype tumors. The deracoxib remission rate (42% CR+PR) compared very favorably to that with single-agent cyclooxygenase inhibitors in more advanced canine InvUC (17-25%), supporting the value of early intervention.

CONCLUSIONS

The study defined a novel naturally-occurring animal model to complement experimental models for early detection and intervention research in InvUC. Research incorporating the canine model is expected to lead to improved outcomes for humans, as well as pet dogs, facing bladder cancer.

Dog-human translational genomics: state of the art and genomic resources

Innovative models for medical research are strongly required nowadays. Convincing evidence supports dog as the most suitable spontaneous model for several human genetic diseases. Decades of studies on dog genome allowed the identification of hundreds of mutations causing genetic disorders, many of which are proposed as counterparts responsible for human diseases. Traditionally, the murine model is the most extensively used in human translational research. However, this species shows large physiological differences from humans, and it is kept under a controlled artificial environment. Conversely, canine genetic disorders often show pathophysiological and clinical features highly resembling the human counterpart. In addition, dogs share the same environment with humans; therefore, they are naturally exposed to many risk factors. Thus, different branches of translational medicine aim to study spontaneously occurring diseases in dogs to provide a more reliable model for human disorders. This review offers a comprehensive overview of the knowledge and resources available today for all the researchers involved in the field of dog-human translational medicine. Some of the main successful examples from dog-human translational genomics are reported, such as the canine association studies which helped to identify the causal mutation in the human counterpart. We also illustrated the ongoing projects aiming to create public canine big datasets. Finally, specific online databases are discussed along with several information resources that can speed up clinical translational research.

Persistent γ-H2AX formation and expression of stem cell markers in N-butyl-N-(4-hydroxybutyl)nitrosamine-induced bladder carcinogenesis in rats

We investigated γ-H2AX formation, a biomarker of DNA damage, and expression of stem cell markers (SCMs), including cytokeratin 14, aldehyde dehydrogenase 1A1 (ALDH1A1), and CD44, in the development of rat bladder tumors induced by short-term administration of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Histopathological examination showed that diffuse simple hyperplasia of the bladder urothelium induced by BBN recovered to the normal-appearing urothelium after withdrawal, whereas focal proliferative lesions were newly developed and subsequently progressed to benign papilloma and carcinoma. Immunohistochemical analysis revealed that BBN-induced γ-H2AX formation and ALDH1A1 and CD44 expression persisted at higher levels in the normal-appearing urothelium than those in the control group for long periods after withdrawal. Since persistent chronic inflammation was observed even after withdrawal, targeted gene expression analysis of inflammation-related factors revealed 101 genes, including Stat3 and Myc, that showed persistent high expression. Pathway analysis suggested that Stat3 and/or Myc activation may be associated with SCM expression. We focused on hepatocyte growth factor (Hgf), one of the genes predicted in relation to Stat3/Myc, and confirmed that HGF-positive cells increased by BBN persisted in the normal-appearing urothelium after withdrawal and colocalized with γ-H2AX and SCMs. These results suggested that the long-term persistence of γ-H2AX formation and SCM expression, which occurred during the early stages of bladder tumorigenesis, is not a transient response to exposure and might contribute to bladder tumorigenesis. Although further studies are needed, BBN-induced rat bladder tumors may originate from focal hyperplasia arising from SCM-positive cells via activation of the STAT3/MYC pathway after DNA damage involving γ-H2AX formation.

Urinary Tract Tumor Organoids Reveal Eminent Differences in Drug Sensitivities When Compared to 2-Dimensional Culture Systems

Generation of organoids from urinary tract tumor samples was pioneered a few years ago. We generated organoids from two upper tract urothelial carcinomas and from one bladder cancer sample, and confirmed the expression of cytokeratins as urothelial antigens, vimentin as a mesenchymal marker, and fibroblast growth factor receptor 3 by immunohistochemistry. We investigated the dose response curves of two novel components, venetoclax versus S63845, in comparison to the clinical standard cisplatin in organoids in comparison to the corresponding two-dimensional cultures. Normal urothelial cells and tumor lines RT4 and HT1197 served as controls. We report that upper tract urothelial carcinoma cells and bladder cancer cells in two-dimensional cultures yielded clearly different sensitivities towards venetoclax, S63845, and cisplatin. Two-dimensional cultures were more sensitive at low drug concentrations, while organoids yielded higher drug efficacies at higher doses. In some two-dimensional cell viability experiments, colorimetric assays yielded different IC₅₀ toxicity levels when compared to chemiluminescence assays. Organoids exhibited distinct sensitivities towards cisplatin and to a somewhat lesser extent towards venetoclax or S63845, respectively, and significantly different sensitivities towards the three drugs investigated when compared to the corresponding two-dimensional cultures. We conclude that organoids maintained inter-individual sensitivities towards venetoclax, S63845, and cisplatin. The preclinical models and test systems employed may bias the results of cytotoxicity studies.

Gold Glyconanoparticles Combined with 91–99 Peptide of the Bacterial Toxin, Listeriolysin O, Are Efficient Immunotherapies in Experimental Bladder Tumors

Simple Summary

We propose a novel type of immunotherapy for bladder cancer using gold nanoparticles bound to a peptide of a bacterial toxin with anti-tumor capacities as listeriolysin O called Listeria nanovaccines. Here, we present the pre-clinical experiments on a mice model of bladder cancer and blood cells of patients with bladder cancer using these Listeria nanovaccines that activate the immune system, block the tumor immunosuppression environment, and reduce the tumor size. The impact of Listeria nanovaccines on the field of immunotherapies for solid tumors can be extended to other solid tumors containing lymphocyte infiltration. Therefore, we propose Listeria nanovaccines as immunotherapy for tumors such as melanoma, urothelial bladder carcinoma, non-small cell lung carcinoma, and glioblastoma.

Abstract

This study presents proof of concept assays to validate gold nanoparticles loaded with the bacterial peptide 91–99 of the listeriolysin O toxin (GNP-LLO_91–99 nanovaccines) as immunotherapy for bladder tumors. GNP-LLO_91–99 nanovaccines showed adjuvant abilities as they induce maturation and activation of monocyte-derived dendritic cells (MoDCs) to functional antigen-presenting cells in healthy donors and patients with melanoma or bladder cancer (BC), promoting a Th1 cytokine pattern. GNP-LLO_91–99 nanovaccines were also efficient dendritic cell inducers of immunogenic tumor death using different bladder and melanoma tumor cell lines. The establishment of a pre-clinical mice model of subcutaneous BC confirmed that a single dose of GNP-LLO_91–99 nanovaccines reduced tumor burden 4.7-fold and stimulated systemic Th1-type immune responses. Proof of concept assays validated GNP-LLO_91–99 nanovaccines as immunotherapy by comparison to anti-CTLA-4 or anti-PD-1 antibodies. In fact, GNP-LLO_91–99 nanovaccines increased percentages of CD4⁺ and CD8⁺ T cells, B cells, and functional antigen-presenting DCs in tumor-infiltrated lymphocytes, while they reduced the levels of myeloid-derived suppressor cells (MDSC) and suppressor T cells (T_reg). We conclude that GNP-LLO_91–99 nanovaccines can work as monotherapies or combinatory immunotherapies with anti-CTLA-4 or anti-PD-1 antibodies for solid tumors with high T cell infiltration, such as bladder cancer or melanoma.

Cell death-induced immunogenicity enhances chemoimmunotherapeutic response by converting immune-excluded into T-cell inflamed bladder tumors

Chemoimmunotherapy has recently failed to demonstrate significant clinical benefit in advanced bladder cancer patients; and the mechanism(s) underlying such suboptimal response remain elusive. To date, most studies have focused on tumor-intrinsic properties that render them "immune-excluded". Here, we explore an alternative, drug-induced mechanism that impedes therapeutic response via disrupting the onset of immunogenic cell death. Using two immune-excluded syngeneic mouse models of muscle-invasive bladder cancer (MIBC), we show that platinum-based chemotherapy diminishes CD8+ T cell tumor infiltration and constraines their antitumoral activity, despite expression of activation markers IFNγ and granzyme B. Mechanistically, chemotherapy induces the release of prostaglandin E₂ (PGE₂) from dying cancer cells, which is an inhibitory damage-associated molecular pattern (iDAMP) that hinderes dendritic cell maturation. Upon pharmaceutical blockade of PGE₂ release, CD8+ T cells become tumoricidal and display an intraepithelial-infiltrating (or inflamed) pattern. This "iDAMP blockade" approach synergizes with chemotherapy and sensitizes bladder tumors towards anti-PD1 immune checkpoint inhibitor therapy. These findings provide a compelling rationale to evaluate this drug combination in future clinical trials.

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

Cancer of the urinary bladder is a neoplasm with considerable importance in veterinary medicine, given its high incidence in several domestic animal species and its life-threatening character. Bladder cancer in companion animals shows a complex and still poorly understood biopathology, and this lack of knowledge has limited therapeutic progress over the years. Even so, important advances concerning the identification of tumour markers with clinical applications at the diagnosis, prognosis and therapeutic levels have recently been made, for example, the identification of pathological BRAF mutations. Those advances are now facilitating the introduction of targeted therapies. The present review will address such advances, focusing on small animal oncology and providing the reader with an update on this field. When appropriate, comparisons will be drawn with bladder cancer in human patients, as well as with experimental models of the disease.

Retraction: Constantin et al. Animal Models in Bladder Cancer. Biomedicines 2021, 9, 1762

The journal retracts the article, “Animal Models in Bladder Cancer. Biomedicines 2021, 9, 1762” [...]

Animal Models in Bladder Cancer

BACKGROUND

Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with an increasing incidence and mortality. Mouse models of bladder cancer should possess a high value of reproducibility, predictability, and translatability to allow mechanistic, chemo-preventive, and therapeutic studies that can be furthered into human clinical trials.

OBJECTIVES

To provide an overview and resources on the origin, molecular and pathological characteristics of commonly used animal models in bladder cancer.

METHODS

A PubMed and Web of Science search was performed for relevant articles published between 1980 and 2021 using words such as: "bladder" and/or "urothelial carcinoma" and animal models. Animal models of bladder cancer can be categorized as autochthonous (spontaneous) and non-autochthonous (transplantable). The first are either chemically induced models or genetically engineered models. The transplantable models can be further subclassified as syngeneic (murine bladder cancer cells implanted into immunocompetent or transgenic mice) and xenografts (human bladder cancer cells implanted into immune-deficient mice). These models can be further divided-based on the site of the tumor-as orthotopic (tumor growth occurs within the bladder) and heterotopic (tumor growth occurs outside of the bladder).

Comparative Cancer Cell Signaling in Muscle-Invasive Urothelial Carcinoma of the Bladder in Dogs and Humans

Muscle-invasive urothelial carcinoma (MIUC) is the most common type of bladder malignancy in humans, but also in dogs that represent a naturally occurring model for this disease. Dogs are immunocompetent animals that share risk factors, pathophysiological features, clinical signs and response to chemotherapeutics with human cancer patients. This review summarizes the fundamental pathways for canine MIUC initiation, progression, and metastasis, emerging therapeutic targets and mechanisms of drug resistance, and proposes new opportunities for potential prognostic and diagnostic biomarkers and therapeutics. Identifying similarities and differences between cancer signaling in dogs and humans is of utmost importance for the efficient translation of in vitro research to successful clinical trials for both species.

Bibliometrics Analysis of Diagnostic Test Accuracy Studies of Bladder Cancer

Background

Bladder cancer is amongst the top 10 most common neoplasms worldwide. It is responsible for over 150,000 deaths per annum. It is of great importance to study its clinical diagnosis and management. As a literature synthesis technique, bibliometrics analysis helps us to take our knowledge of bladder cancer diagnosis research, topics, and trends a step further. It is critical to elucidate the literature landscape and its pertinent impact on this field, in order to have a better understanding and improved management of bladder cancer.

Materials and Methods

Search terms related to bladder cancer diagnosis were used to retrieval publications which met the predefined criteria in the Scopus database developed by Elsevier. Included articles were further evaluated by year of publication, country, language, institution, article type, source journal, coauthorship networks, and text mining of titles. The R software, as well as the tm, ggplot2 packages, and the VOSviewer (version 1.6.15) were used as software tools.

Results

A comprehensive literature search in the Scopus database returned a total of 824 publication items. Among them, 601 (72.94%) were published as journal articles, and 117 (14.20%) were published as reviews. The number of annual publications in this field has been increasing in recent years. English represents the language used in the majority of the articles (634, 77.13%). The highest number of citations received for a single article is as high as 628 times. We also clustered and visualized a network of 701 authors with no less than 3 publications. The term cloud and hierarchical clustering dendrogram which revealed with text mining were used to discover the hot research topics in this field. We also statistically analyzed evolution of the major journal impact indices, including Impact Factor, EigenFactor Score, and CiteScore of 11 journals with a period of 9 years.

Conclusion

Through bibliometrics analysis, we found hot topics and related research focuses and trends in bladder cancer diagnosis. This bibliometrics analysis has identified influential articles in the field and provides a useful guide to researchers as to what type of article constitutes a highly citable publication in this subject. In addition, a coauthorship network helps researchers find out which team may be a potential partner and where their studies focus on.

Intravesical Instillation of Azacitidine Suppresses Tumor Formation through TNF-R1 and TRAIL-R2 Signaling in Genotoxic Carcinogen-Induced Bladder Cancer

Azacitidine, an inhibitor of DNA methylation, shows therapeutic effects against several malignancies by inducing apoptosis and inhibiting tumor cell proliferation. However, the anti-tumor effects of azacitidine on urinary bladder urothelial carcinoma (UBUC), especially following intravesical instillation (IVI), are not established. Here, UBUC cell lines were used to analyze the in vitro therapeutic effects of azacitidine. Potential signaling pathways were investigated by antibody arrays and Western blotting. The N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced rat UBUC model was used for in vivo quantitative analysis of tumor burden. Azacitidine significantly inhibited DNMT expression in UBUC cell lines and reduced cell viability and clonogenic activity, as determined by MTT and colony formation assays, while also inducing significant cytotoxic effects in the form of increased sub-G1 and Annexin V-PI populations (all p < 0.05). Antibody arrays confirmed the in vitro suppression of TNF-R1 and the induction of TRAIL-R2 and their downstream signaling molecules. TNF-R1 suppression reduced claspin and survivin expression, while TRAIL-R2 activation induced cytochrome C and caspase 3 expression. Rats with BBN-induced bladder cancer had a significantly reduced tumor burden and Ki67 index following IVI of azacitidine (p < 0.01). Our study provides evidence for a reduction in BBN-induced bladder cancer by IVI of azacitidine through alterations in the TRAIL-R2 and TNF-R1 signaling pathways. These findings might provide new insights for further clinical trials.

Preclinical Models for Bladder Cancer Research

At diagnosis, more than 70% of bladder cancers (BCs) are at the non-muscle-invasive bladder cancer (NMIBC) stages, which are usually treated with transurethral resection followed by intravesical instillation. For the remaining advanced cancers, systemic therapy is the standard of care, with addition of radical cystectomy in cases of locally advanced cancer. Because of the difference in treatment modalities, different models are needed to advance the care of NMIBC and advanced BC. This article gives a comprehensive review of both in vitro and in vivo BC models and compares the advantages and drawbacks of these preclinical systems in BC research.

Vitamin A and Retinoids in Bladder Cancer Chemoprevention and Treatment: A Narrative Review of Current Evidence, Challenges and Future Prospects

Bladder cancer (BC) is the tenth most common cancer worldwide with a high recurrence rate, morbidity and mortality. Therefore, chemoprevention and improved treatment of BC are of paramount importance. Epidemiological studies suggest that adequate vitamin A intake may be associated with reduced BC risk. In addition, retinoids, natural and synthetic derivatives of vitamin A, are intensively studied in cancer research due to their antioxidant properties and their ability to regulate cell growth, differentiation, and apoptosis. Findings from in vivo and in vitro models of BC show great potential for the use of retinoids in the chemoprevention and treatment of BC. However, translation to the clinical practice is limited. In this narrative review we discuss: (i) vitamin A and retinoid metabolism and retinoic acid signalling, (ii) the pathobiology of BC and the need for chemoprevention, (iii) the epidemiological evidence for the role of dietary vitamin A in BC, (iv) mechanistic insights obtained from in vivo and in vitro models, (v) clinical trials of retinoids and the limitations of retinoid use, (vi) novel systems of retinoid delivery, and (vii) components of retinoid signalling pathways as potential novel therapeutic targets.

Preventive effect of pomegranate juice against chemically induced bladder cancer: An experimental study

OBJECTIVES

Pomegranate juice (PJ) is rich in important compounds with anti-cancer activities. This study aims to investigate the preventive effect of pomegranate juice (PJ) against bladder cancer (BC).

METHODS

Eighty male Sprague Dawley rats were randomly classified into 4 equal groups: (1) Normal controls; (2) PJ group: supplied by PJ for 12 weeks; (3) Cancer-induced group: intake 0.05% v/v N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) for 8 weeks; (4) Cancer-prevented group: BBN + PJ. After 12 weeks, all rats were sacrificed and their urinary bladder tissues were subjected to histopathological and immunohistochemical (p53) examinations, expression of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), hypoxia-inducible factor 1 (HIF-1) and the tumor protein p53 (TP53) and analysis of oxidative stress markers.

RESULTS

The development of BC was: 0/20 (0%) in normal, PJ and cancer-prevented groups and 20/20 (100%) in cancer-induced group. Significant neoplastic lesions were observed in cancer-induced group. Mild preneoplastic alterations were noticed in 25% (5/20) of cancer-prevented group. p53 immunostaining were significantly elevated in the cancer-induced group, which was decreased in the cancer-prevented group. The relative expressions of IL-6, TNF-α, HIF-1 and TP53 were significantly lower in the cancer-prevented group compared to the cancer-treated group. Correction in the oxidative stress markers were also observed in the cancer-prevented group.

CONCLUSION

PJ possesses a promising inhibitory effect on BC development, probably due to its anti-oxidant and anti-inflammatory properties.

Spontaneous and Induced Animal Models for Cancer Research

Considering the complexity of the current framework in oncology, the relevance of animal models in biomedical research is critical in light of the capacity to produce valuable data with clinical translation. The laboratory mouse is the most common animal model used in cancer research due to its high adaptation to different environments, genetic variability, and physiological similarities with humans. Beginning with spontaneous mutations arising in mice colonies that allow for pursuing studies of specific pathological conditions, this area of in vivo research has significantly evolved, now capable of generating humanized mice models encompassing the human immune system in biological correlation with human tumor xenografts. Moreover, the era of genetic engineering, especially of the hijacking CRISPR/Cas9 technique, offers powerful tools in designing and developing various mouse strains. Within this article, we will cover the principal mouse models used in oncology research, beginning with behavioral science of animals vs. humans, and continuing on with genetically engineered mice, microsurgical-induced cancer models, and avatar mouse models for personalized cancer therapy. Moreover, the area of spontaneous large animal models for cancer research will be briefly presented.

Mechanisms of Macrophage Immunomodulatory Activity Induced by a New Polysaccharide Isolated From Polyporus umbellatus (Pers.) Fries

Bladder cancer is one of the most malignant tumors closely associated with macrophage immune dysfunction. The Chinese medicine polyporus has shown excellent efficacy in treating bladder cancer, with minimal side effects. However, its material basis and mechanism of action remain unclear. A new water-soluble polysaccharide (HPP) with strong immunomodulatory activity was isolated from the fungus Polyporus umbellatus (Pers.) Fries. HPP had an average molecular weight of 6.88 kDa and was composed mainly of an <-(1 → 4)-linked D-galactan backbone. The immunomodulatory activity of HPP was determined in vitro, and the results revealed that it could obviously increase the secretion of immune factors by IFN-γ-stimulated macrophages, including nitric oxide (NO), interleukin-6 (IL-6), interleukin-1β (IL-1β), RANTES and interleukin-23 (IL-23), and the expression of the cell membrane molecule CD80. In addition, HPP was recognized by Toll-like receptor 2 (TLR2) and activated the signaling pathways of NF-κB and NLRP3 in a bladder cancer microenvironment model, indicating that HPP could enhance host immune system function. These findings demonstrated that HPP may be a potential immune modulator in the treatment of immunological diseases or bladder cancer therapy.

Enhanced metastatic potential in the MB49 urothelial carcinoma model

Recent data suggest that patients with a basal/stem-like bladder cancer (BC) subtype tend to have metastatic disease, but this is unconfirmed. Here we report the identification of murine MB49 cell line sub-clones with stem-like characteristics in culture. Subcutaneous implantation of S2 and S4 MB49 sub-clones into immunocompetent mice resulted in lung metastases in 50% and 80% of mice respectively, whereas none of the mice implanted with the parental cells developed metastasis. Gene profiling of cells cultured from S2 and S4 primary and metastatic tumors revealed that a panel of genes with basal/stem-like/EMT properties is amplified during metastatic progression. Among them, ITGB1, TWIST1 and KRT6B are consistently up-regulated in metastatic tumors of both MB49 sub-clones. To evaluate clinical relevance, we examined these genes in a human public dataset and found that ITGB1 and KRT6B expression in BC patient tumor samples are positively correlated with tumor grade. Likewise, the expression levels of these three genes are correlated with worse clinical outcomes. This MB49 BC metastatic pre-clinical model provides a unique opportunity to validate and recapitulate results discovered in patient studies and to pursue future mechanistic therapeutic interventions for BC metastasis.

Xenografting for disease modeling of intramedullary spinal cord tumors: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVES

The overall incidence of intramedullary spinal cord tumors (IMSCT) remains low and clinical trials or standardized treatment strategies are missing. Therefore, multiple animal-based xenograft models (AXM) have been developed to foster preclinical research efforts on IMSCT. We constructed a systematic literature review to summarize and compare all AXM for IMSCT, published until April 16, 2018.

METHODS

The review was conducted using 4 independent research databases following the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines. Studies were included, if they reported on surgical transplantation of tumor cells or tumor tissue to the spinal cord. Methodological study quality was assessed according to the SYRCLE (systematic review center for laboratory animal experimentation) risk of Bias tool.

RESULTS

Systematic search yielded 20 publications dealing with AXM for IMSCT. In summary, 4 tumor entities were analyzed in 23 experiments using ~337 animals, mainly investigating glioblastoma or gliosarcoma biology. Studies varied regarding the use of engrafted animals, surgical techniques and tumor burden. Most commonly authors used heterotopic, transdural injection of immortalized brain tumor cell lines (1 × 10⁵ in 5 µl) into the thoracic spinal cord of immunocompromised rats. Quality assessment demonstrated an unclear risk of bias in most cases.

CONCLUSION

Although different AXM for IMSCT have been described so far, one rat model is technically feasible, enables robust experiments and demonstrates reproducible results. However, there is a need for new AXM using orthotopic engraftment of patient-derived tumor cells and for genetically engineered animal models.

Implantable orthotopic bladder cancer model in Wistar rats: A pilot and feasibility study

Purpose: The implantable bladder cancer (BC) models allow the researchers to perform rapid and useful experiments for BC. We investigated the implantation success of BC cells obtained from Wistar rats (grown in vitro), into bladders of syngeneic Wistar rats, which are commonly used in the laboratories.

Methods: The Nara Bladder Tumor No.2 (NBT-II) BC cells induced with 4-hydroxybutylnitrosamine were grown with passages in Kocaeli University Center for Stem-Cell and Gene-Therapies. After urothelial denudation, 2x106 NBT-II cells were then implanted into bladders of 24 female Wistar rats (aged 7-8 weeks). The rats were randomly divided into four experimental groups; three instillation groups (8 per group) and one sham-operated control group consisting of 6 rats. First, second and third instillation groups were sacrificed at days 7, 14, and 21, respectively, and, bladders were histopathologically evaluated for BC according to WHO / International Society of Urological Pathology.

Results: All tumors were pT1 (including 1 rat that prematurely died at 5th day), except one rat that died prematurely at 8th day had pT2 tumor. Implantation rates were 28.58% (2/7) in the first group, and 42.85% (3/7) in the second, for a cumulative rate of 35.71% (5/14) in these two-groups (until 14th day). Interestingly, there was no tumor in the third group, but there was an inflammatory granulation tissue.

Conclusion: Seeding NBT-II cells into bladders of Wistar rats was described, successfully tested and demonstrated in this study. This implantable BC model of Wistar rats may be improved to increase the success rate of BC cell implantation in new studies with higher number of animals.

Association of Glutathione S-transferase gene polymorphism with bladder Cancer susceptibility

BACKGROUND

We conducted a meta-analysis to evaluate the relationship between the glutathione S-transferase μ1 (GSTM1)- and glutathione S-transferase θ1 (GSTT1)- null genotypes and susceptibility to bladder cancer.

METHODS

We identified association reports from the databases of PubMed, Embase, the Cochrane Library and the China Biological Medicine Database (CBM disc) on July 1, 2017 and synthesized eligible investigations. Results were expressed using odds ratios (ORs) for dichotomous data, and we also calculated 95% confidence intervals (CIs).

RESULTS

In this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians (overall population: OR = 1.40, 95% CI: 1.31-1.48, P<0.00001; whites: OR = 1.39, 95% CI: 1.26-1.54, P<0.00001; Africans: OR = 1.54, 95% CI: 1.16-2.05, P = 0.003; Asians: OR = 1.45, 95% CI: 1.33-1.59, P<0.00001). The GSTT1-null genotype was associated with bladder cancer risk in the overall population, but not in whites, in Africans or Asians (overall population: OR = 1.11, 95% CI: 1.01-1.22, P = 0.03; whites: OR = 1.16, 95% CI: 0.99-1.36, P = 0.07; Africans: OR = 1.07, 95% CI: 0.65-1.76, P = 0.79; Asians: OR = 1.05, 95% CI: 0.91-1.22, P = 0.51). Interestingly, a dual-null GSTM1-GSTT1 genotype was associated with bladder cancer risk in the overall population and in Asians (overall population: OR = 1.48, 95% CI: 1.15-1.92, P = 0.002; Asians: OR = 1.62, 95% CI: 1.15-2.28, P = 0.006). In conclusion, the GSTM1-null, GSTT1-null and dual-null GSTM1-GSTT1 genotypes might be associated with the onset of bladder cancer, but additional genetic-epidemiological studies should be conducted to explore this association further.

IC-2 Suppresses Proliferation and Induces Apoptosis of Bladder Cancer Cells via the Wnt/β-Catenin Pathway

Background

The Wnt/β-catenin signaling pathway participates in many important tumorigeneses processes, including bladder cancer. The inhibition of abnormal activation of Wnt pathways might provide a new approach to tumor treatment. In the present study, we investigated the role of IC-2, a novel Wnt pathways small molecular inhibitor, in bladder cancer tumorigenesis.

Material/Methods

Bladder cancer cells were treated with various concentrations of IC-2 (0–5 μM) in vitro. The proliferation ability was measured using colony formation assay and apoptosis was measured using flow cytometry analysis. The protein expression was detected using Western blot analysis. Xenograft in vivo assay was performed to assess tumor growth.

Results

IC-2 suppressed the proliferation and aggravated the apoptosis of bladder cancer cells in dose-dependent and time-dependent manners in vitro. Moreover, high concentrations of IC-2 inhibited the Wnt pathway-related protein expression levels, including β-catenin, Cyclin D1, and TCF4. In vivo, administration of IC-2 in xenograft mice decreased the β-catenin expression and reduced the tumor volume.

Conclusions

Our results validate the tumor-inhibition effect of IC-2 on bladder cancer in vivo and in vitro, providing a novel therapeutic strategy for bladder cancer.

Tumor inhibitory effects of intravesical Ganoderma lucidum instillation in the syngeneic orthotopic MB49/C57 bladder cancer mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (GL) has been traditionally used in oriental medicine as superior health tonic, and there are numerous scientific evidences of its antitumorigenic activities.

AIM OF THE STUDY

To evaluate the intravesical chemopreventive effects of ethanol extract of GL (GLe) on bladder cancer.

MATERIALS AND METHODS

Intravesical therapy is defined as the direct instillation of a liquid drug into bladder through a catheter. Bacille Calmette-Guerin(BCG) solution is applied intravesically as a conventional immunotherapy for preventing recurrence of bladder cancer. By adopting the MB49/C57 bladder cancer mice model, an overall 60 MB49-implanted mice were randomized into 3 groups and treated according to 3 treatment arms, including GLe, BCG and PBS. Additionally, wild-type mice without MB49 cell inoculation and treated with PBS were used as the negative control group. Testing agents were instilled intravesically for 2 h and repeated after one week for evaluating the effects on preventing the tumor formation and growth. The treated-mice were closely monitored for major adverse effects.

RESULTS

GLe demonstrated more potent cytotoxic effects than BCG on MB49 cells, although both in dose-dependent manner. In the MB49-implanted mice, 80 µg/ml GLe was shown to delay the tumor formation by one week, whereas the averaged tumor volume measured at endpoint was 3.6-fold and 4.6-fold smaller than that of the BCG or PBS, respectively. However, no significant effects were observed on body weight and hematuria.

CONCLUSION

Current findings in mice suggested intravesical GLe therapy as an effective and safe chemopreventive strategy for inhibiting bladder tumor formation.

Oncogene miR-187-5p is associated with cellular proliferation, migration, invasion, apoptosis and an increased risk of recurrence in bladder cancer

BACKGROUND

Bladder cancer, the ninth-most-common malignancy worldwide with an estimated 356,000 new cases and 145,000 deaths annually, has a propensity to relapse, requiring lifelong monitoring after diagnosis. 75% patients diagnosed with BC are non-muscle invasive BC and over 50% of them experience recurrences within 6-12 years of initial diagnosis. miRNA are small, noncoding RNA and shown to be oncogenes or anti-oncogenes in bladder cancer, contributing to numerous BC cell processes, including cell proliferation, differentiation, migration and apoptosis.

METHODS

RT-qPCR were performed to detect the expression of miR-187-5p in tissues and cell lines, After which, clinicopathological variables and the prognostic value of altered miR-187-5p expression in BC was analyzed with the 48 formalin-fixed paraffin-embedded BC samples. Moreover, Cell functional assays (wound healing assay, CCK-8 assay, transwell assay and flow cytometry assay) were performed to explore the relationship between miR-187-5p expression and cell proliferation, migration, invasion and apoptosis in BC.

RESULTS

Up-regulation of miR-187-5p was observed in BC tissues and BC cell lines. Cox proportional hazard regression analysis demonstrated that the patients with low expression of miR-187-5p experience lower risks of recurrence in the univariate and multivariate analysis. The Kaplan-Meier recurrence-free curves suggested that the patients with low expression of miR-187-5p experience lower risks of recurrence. Up-regulation of miR-187-5p promotes cell proliferation and mobility and inhibits the apoptosis of 5637 and UM-UC-3 cell, while down-regulation of miR-187-5p reverses these effects.

CONCLUSIONS

The results of our study demonstrated that oncogene miR-187-5p is associated with cellular proliferation, migration, invasion, apoptosis and an increased risk of recurrence in bladder cancer.

The dog as an animal model for bladder and urethral urothelial carcinoma: Comparative epidemiology and histology

Despite the recent approval of several novel agents for patients with metastatic urothelial carcinoma (UC), survival in this setting remains poor. As such, continued investigation into novel therapeutic options remains warranted. Pre-clinical development of novel treatments requires an animal model that accurately simulates the disease in humans. The aim of the present study was to evaluate the dog as an animal model for human UC. A total of 260 cases of spontaneous, untreated canine primary urethral and urinary bladder UC, were epidemiologically and histologically assessed and classified based on the current 2016 World Health Organization (WHO) tumor classification system. Canine data was compared with human data available from scientific literature. The mean age of dogs diagnosed with UC was 10.22 years (range, 4–15 years), which is equivalent to 60–70 human years. The results revealed a high association between UC diagnosis with the female sex [odds ratio (OR) 3.51; 95% confidence interval (CI) 2.57–4.79; P<0.001], surgical neutering (OR 4.57; 95% CI 1.87–11.12; P<0.001) and breed (OR 15.11 for Scottish terriers; 95% CI 8.99–25.41; P<0.001). Based on the 2016 WHO tumor (T), node and metastasis staging system, the primary tumors were characterized as T1 (38%), T2a (28%), T2b (13%) and T3 (22%). Non-papillary, flat subgross tumor growth was strongly associated with muscle invasion (OR 31.00; P<0.001). Irrespective of subgross growth pattern, all assessable tumors were invading beyond the basement membrane compatible with infiltrating UC. Conventional, not further classifiable infiltrating UC was the most common type of tumor (90%), followed by UC with divergent, squamous and/or glandular differentiation (6%). Seven out of the 260 (2.8%) cases were classified as non-urothelial based on their histological morphology. These cases included 5 (2%) squamous cell carcinomas, 1 (0.4%) adenocarcinoma and 1 (0.4%) neuroendocrine tumor. The 2 most striking common features of canine and human UC included high sex predilection and histological tumor appearance. The results support the suitability of the dog as an animal model for UC and confirm that dogs also spontaneously develop rare UC subtypes and bladder tumors, including plasmacytoid UC and neuroendocrine tumor, which are herein described for the first time in a non-experimental animal species.

Systematic Review: Characteristics and Preclinical Uses of Bladder Cancer Cell Lines

BACKGROUND

Bladder cancer (BC) cell lines are indispensable in basic and preclinical research. Currently, an up-to-date and comprehensive overview of available BC cell lines is not available.

OBJECTIVE

To provide an overview and resources on the origin, pathological and molecular characteristics of commonly used human, murine and canine BC cell lines.

METHODS

A PubMed search was performed for relevant articles published between 1980 and 2017 according to the following MeSH terms: cell line; cell line, tumor; urinary bladder neoplasms; carcinoma, transitional cell. The Cellosaurus database was searched, using the term "bladder" and/or "urothelial carcinoma". We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

We provide information on 157 human, murine and canine BC cell lines. 103 human BC cell lines have molecular data available, of which 69 have been profiled by at least one "omic" technology. We outline how these cell lines are currently being used for in vitro and in vivo experimental models. These results allow direct comparison of BC cell lines to patient samples, providing information needed to make informed decisions on the most genomically appropriate cell line to answer research questions. Furthermore, we show that cross-contamination remains an issue and describe guidelines for prevention.

CONCLUSIONS

In the BC field, multiple human, murine and canine BC cell lines have been developed and many have become indispensable for in vitro and in vivo research. High-throughput -omic technologies have dramatically increased the amount of molecular data on these cell lines. We synthesized a comprehensive overview of these data as a resource for the BC scientific community.

Hurdles in Basic Science Translation

In the past century there have been incredible advances in the field of medical research, but what hinders translation of this knowledge into effective treatment for human disease? There is an increasing focus on the failure of many research breakthroughs to be translated through the clinical trial process and into medical practice. In this mini review, we will consider some of the reasons that findings in basic medical research fail to become translated through clinical trials and into basic medical practices. We focus in particular on the way that human disease is modeled, the understanding we have of how our targets behave in vivo, and also some of the issues surrounding reproducibility of basic research findings. We will also look at some of the ways that have been proposed for overcoming these issues. It appears that there needs to be a cultural shift in the way we fund, publish and recognize quality control in scientific research. Although this is a daunting proposition, we hope that with increasing awareness and focus on research translation and the hurdles that impede it, the field of medical research will continue to inform and improve medical practice across the world.