Experimental models of human bladder carcinogenesis

Modelling the Tumour Microenvironment, but What Exactly Do We Mean by "Model"?

The Oxford English Dictionary includes 17 definitions for the word "model" as a noun and another 11 as a verb. Therefore, context is necessary to understand the meaning of the word model. For instance, "model railways" refer to replicas of railways and trains at a smaller scale and a "model student" refers to an exemplary individual. In some cases, a specific context, like cancer research, may not be sufficient to provide one specific meaning for model. Even if the context is narrowed, specifically, to research related to the tumour microenvironment, "model" can be understood in a wide variety of ways, from an animal model to a mathematical expression. This paper presents a review of different "models" of the tumour microenvironment, as grouped by different definitions of the word into four categories: model organisms, in vitro models, mathematical models and computational models. Then, the frequencies of different meanings of the word "model" related to the tumour microenvironment are measured from numbers of entries in the MEDLINE database of the United States National Library of Medicine at the National Institutes of Health. The frequencies of the main components of the microenvironment and the organ-related cancers modelled are also assessed quantitatively with specific keywords. Whilst animal models, particularly xenografts and mouse models, are the most commonly used "models", the number of these entries has been slowly decreasing. Mathematical models, as well as prognostic and risk models, follow in frequency, and these have been growing in use.

Chronic Arsenic Exposure Upregulates the Expression of Basal Transcriptional Factors and Increases Invasiveness of the Non-Muscle Invasive Papillary Bladder Cancer Line RT4

The bladder is a target organ for inorganic arsenic, a carcinogen and common environmental contaminant found in soil and water. Urothelial carcinoma (UC) is the most common type of bladder cancer (BC) that develops into papillary or non-papillary tumors. Papillary tumors are mostly non-muscle invasive (NMIUC), easier treated, and have a better prognosis. Urothelial carcinoma can be molecularly sub-typed as luminal or basal, with papillary tumors generally falling into the luminal category and basal tumors exclusively forming muscle invasive urothelial carcinomas (MIUC). It is unclear why some UCs develop more aggressive basal phenotypes. We hypothesized that chronic arsenic exposure of a papillary luminal bladder cancer would lead to the development of basal characteristics and increase in invasiveness. We treated the human papillary bladder cancer cell line RT4 with 1 µM arsenite (As³⁺) for twenty passages. Throughout the study, key luminal and basal gene/protein markers in the exposed cells were evaluated and at passage twenty, the cells were injected into athymic mice to evaluate tumor histology and measure protein markers using immunohistochemistry. Our data indicates that chronic As³⁺- treatment altered cellular morphology and decreased several luminal markers in cell culture. The histology of the tumors generated from the As³⁺-exposed cells was similar to the parent (non-treated) however, they appeared to be more invasive in the liver and displayed elevated levels of some basal markers. Our study demonstrates that chronic As³⁺ exposure is able to convert a non-invasive papillary bladder cancer to an invasive form that acquires some basal characteristics.

Pre-clinical and clinical studies on the role of RBM3 in muscle-invasive bladder cancer: longitudinal expression, transcriptome-level effects and modulation of chemosensitivity

Background

The response to neoadjuvant cisplatin-based chemotherapy (NAC) in muscle-invasive bladder cancer (MIBC) is impaired in up to 50% of patients due to chemoresistance, with no predictive biomarkers in clinical use. The proto-oncogene RNA-binding motif protein 3 (RBM3) has emerged as a putative modulator of chemotherapy response in several solid tumours but has a hitherto unrecognized role in MIBC.

Methods

RBM3 protein expression level in tumour cells was assessed via immunohistochemistry in paired transurethral resection of the bladder (TURB) specimens, cystectomy specimens and lymph node metastases from a consecutive cohort of 145 patients, 65 of whom were treated with NAC. Kaplan-Meier and Cox regression analyses were applied to estimate the impact of RBM3 expression on time to recurrence (TTR), cancer-specific survival (CSS), and overall survival (OS) in strata according to NAC treatment. The effect of siRNA-mediated silencing of RBM3 on chemosensitivity was examined in RT4 and T24 human bladder carcinoma cells in vitro. Cellular functions of RBM3 were assessed using RNA-sequencing and gene ontology analysis, followed by investigation of cell cycle distribution using flow cytometry.

Results

RBM3 protein expression was significantly higher in TURB compared to cystectomy specimens but showed consistency between primary tumours and lymph node metastases. Patients with high-tumour specific RBM3 expression treated with NAC had a significantly reduced risk of recurrence and a prolonged CSS and OS compared to NAC-untreated patients. In high-grade T24 carcinoma cells, which expressed higher RBM3 mRNA levels compared to RT4 cells, RBM3 silencing conferred a decreased sensitivity to cisplatin and gemcitabine. Transcriptomic analysis revealed potential involvement of RBM3 in facilitating cell cycle progression, in particular G₁/S-phase transition, and initiation of DNA replication. Furthermore, siRBM3-transfected T24 cells displayed an accumulation of cells residing in the G₁-phase as well as altered levels of recognised regulators of G₁-phase progression, including Cyclin D1/CDK4 and CDK2.

Conclusions

The presented data highlight the potential value of RBM3 as a predictive biomarker of chemotherapy response in MIBC, which could, if prospectively validated, improve treatment stratification of patients with this aggressive disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09168-7.

Testosterone status is not associated with bladder cancer parameters in adult male patients: results of a prospective controlled study

PURPOSE

This controlled study assessed whether there was a correlation between serum total testosterone levels and bladder cancer (BCa) in terms of tumor grade and stage as objective measures in adult men.

MATERIALS AND METHOD

Our prospectively-designed study included 257 patients who were diagnosed with primary BCa and its surgery between January 2017 and January 2020. Hundred and forty patients who had surgery in the same period with TUR for prostate or endoscopic ureteral stone treatment were included in the study as a control group. All patients in the study and control groups were male. The age range of the patients was between 34 and 90 years old. In order to examine groups, fasting blood glucose, lipid profile, albumin, total testosterone, and vitamin D levels of all patients included in the study.

RESULTS

The relationship between tumor aggression and total testosterone level was investigated with a multinomial logistic regression model, where the control group was accepted as a reference, following adjustment for potential confounding variables, including age and serum albumin levels. Testosterone level was not found to be associated with any of the categories that determine tumor aggressiveness (p > 0.05).

CONCLUSION

In the present study, there was no correlation between any categories that determine tumor aggressiveness of BCa and total testosterone levels in adult men. It is obvious that our findings should be supported and further investigations are needed.

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).

Method for Biomonitoring DNA Adducts in Exfoliated Urinary Cells by Mass Spectrometry

Tobacco smoking contributes to about 50% of the bladder-cancer (BC) cases in the United States. Some aromatic amines in tobacco smoke are bladder carcinogens; however, other causal agents of BC are uncertain. Exfoliated urinary cells (EUCs) are a promising noninvasive biospecimen to screen for DNA adducts of chemicals that damage the bladder genome, although the analysis of DNA adducts in EUCs is technically challenging because of the low number of EUCs and limiting quantity of cellular DNA. Moreover, EUCs and their DNA adducts must remain viable during the time of collection and storage of urine to develop robust screening methods. We employed RT4 cells, a well-differentiated transitional epithelial bladder cell line, as a cell-model system in urine to investigate cell viability and the chemical stability of DNA adducts of two prototypical bladder carcinogens: 4-aminobiphenyl (4-ABP), an aromatic amine found in tobacco smoke, and aristolochic acid I (AA-I), a nitrophenanthrene found in Aristolochia herbaceous plants used for medicinal purposes worldwide. The cell viability of RT4 cells pretreated with 4-ABP or AA-I in urine exceeded 80%, and the major DNA adducts of 4-ABP and AA-I, quantified by liquid chromatography-mass spectrometry, were stable for 24 h. Thereafter, we successfully screened EUCs of mice treated with AA-I to measure DNA adducts of AA-I, which were still detected 25 days following treatment with the carcinogen. EUCs are promising biospecimens that can be employed for the screening of DNA adducts of environmental and dietary genotoxicants that may contribute to the development of BC.

Modeling human bladder cancer

INTRODUCTION

Bladder cancer is a major public health concern and the treatment options available are unable to significantly prevent disease recurrence and progression. The need for experimental tumor models to efficiently reproduce the pathology of human cancers has prompted researchers to attempt various approaches.

METHODS

A PubMed search combining the MeSH bladder cancer and models was executed in March 2017.

RESULTS

We review the advantages and limitations of currently available in vitro 2D and 3D bladder cancer models as well as in vivo rodent models. To date, despite the description of a variety of animal models (including transplantable, carcinogen-induced and genetically engineered models), the establishment of reliable, simple, practicable and reproducible animal models remains an ongoing challenge. Recently, sophisticated 3D culture systems have been designed to better recapitulate the phenotypic and cellular heterogeneity as well as microenvironmental aspects of in vivo tumor growth, while being more flexible to conduct repeated experiments.

CONCLUSION

Selecting the most appropriate model for a specific application will maximize the conversion of potential therapies from the laboratory to clinical practice and requires an understanding of the various models available.

Tobacco-Specific Carcinogens Induce Hypermethylation, DNA Adducts, and DNA Damage in Bladder Cancer

Smoking is a major risk factor for the development of bladder cancer; however, the functional consequences of the carcinogens in tobacco smoke and bladder cancer-associated metabolic alterations remain poorly defined. We assessed the metabolic profiles in bladder cancer smokers and non-smokers and identified the key alterations in their metabolism. LC/MS and bioinformatic analysis were performed to determine the metabolome associated with bladder cancer smokers and were further validated in cell line models. Smokers with bladder cancer were found to have elevated levels of methylated metabolites, polycyclic aromatic hydrocarbons, DNA adducts, and DNA damage. DNA methyltransferase 1 (DNMT1) expression was significantly higher in smokers than non-smokers with bladder cancer. An integromics approach, using multiple patient cohorts, revealed strong associations between smokers and high-grade bladder cancer. In vitro exposure to the tobacco smoke carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene (BaP) led to increase in levels of methylated metabolites, DNA adducts, and extensive DNA damage in bladder cancer cells. Cotreatment of bladder cancer cells with these carcinogens and the methylation inhibitor 5-aza-2'-deoxycytidine rewired the methylated metabolites, DNA adducts, and DNA damage. These findings were confirmed through the isotopic-labeled metabolic flux analysis. Screens using smoke-associated metabolites and DNA adducts could provide robust biomarkers and improve individual risk prediction in bladder cancer smokers. Noninvasive predictive biomarkers that can stratify the risk of developing bladder cancer in smokers could aid in early detection and treatment. Cancer Prev Res; 10(10); 588-97. ©2017 AACR.

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

Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with increasing incidence and mortality. Treatment of bladder cancer has not advanced in the past 30 years. Therefore, there is a crucial unmet need for novel therapies, especially for high grade/stage disease that can only be achieved by preclinical model systems that faithfully recapitulate the human disease. Animal models are essential elements in bladder cancer research to comprehensively study the multistep cascades of carcinogenesis, progression and metastasis. They allow for the investigation of premalignant phases of the disease that are not clinically encountered. They can be useful for identification of diagnostic and prognostic biomarkers for disease progression and for preclinical identification and validation of therapeutic targets/candidates, advancing translation of basic research to clinic. This review summarizes the latest advances in the currently available bladder cancer animal models, their translational potential, merits and demerits, and the prevalent tumor evaluation modalities. Thereby, findings from these model systems would provide valuable information that can help researchers and clinicians utilize the model that best answers their research questions.

A redox state-dictated signalling pathway deciphers the malignant cell specificity of CD40-mediated apoptosis

CD40, a member of the tumour necrosis factor receptor (TNFR) superfamily, has the capacity to cause extensive apoptosis in carcinoma cells, while sparing normal epithelial cells. Yet, apoptosis is only achieved by membrane-presented CD40 ligand (mCD40L), as soluble receptor agonists are but weakly pro-apoptotic. Here, for the first time we have identified the precise signalling cascade underpinning mCD40L-mediated death as involving sequential TRAF3 stabilisation, ASK1 phosphorylation, MKK4 (but not MKK7) activation and JNK/AP-1 induction, leading to a Bak- and Bax-dependent mitochondrial apoptosis pathway. TRAF3 is central in the activation of the NADPH oxidase (Nox)-2 component p40phox and the elevation of reactive oxygen species (ROS) is essential in apoptosis. Strikingly, CD40 activation resulted in down-regulation of Thioredoxin (Trx)-1 to permit ASK1 activation and apoptosis. Although soluble receptor agonist alone could not induce death, combinatorial treatment incorporating soluble CD40 agonist and pharmacological inhibition of Trx-1 was functionally equivalent to the signal triggered by mCD40L. Finally, we demonstrate using normal, ‘para-malignant' and tumour-derived cells that progression to malignant transformation is associated with increase in oxidative stress in epithelial cells, which coincides with increased susceptibility to CD40 killing, while in normal cells CD40 signalling is cytoprotective. Our studies have revealed the molecular nature of the tumour specificity of CD40 signalling and explained the differences in pro-apoptotic potential between soluble and membrane-bound CD40 agonists. Equally importantly, by exploiting a unique epithelial culture system that allowed us to monitor alterations in the redox-state of epithelial cells at different stages of malignant transformation, our study reveals how pro-apoptotic signals can elevate ROS past a previously hypothesised ‘lethal pro-apoptotic threshold' to induce death; an observation that is both of fundamental importance and carries implications for cancer therapy.

The New Immortalized Uroepithelial Cell Line HBLAK Contains Defined Genetic Aberrations Typical of Early Stage Urothelial Tumors

Background: Cell culture models of normal urothelial cells are important for studying differentiation, disease mechanisms and anticancer drug development. Beyond primary cultures with their limitations in lifespan, interindividual heterogeneity and supply, few conditionally immortalized cell lines with limited applicability due to partial transformation or impaired differentiation capacity are available. We describe characteristics of the new spontaneously immortalized cell line HBLAK derived from a primary culture of uroepithelial cells.

Objective: To characterize utility and limitations of HBLAK cells as an urothelial cell culture model.

Methods: Differentiation markers were investigated by immunofluorescence and RT-PCR, genetic changes by standard karyotyping, array-CGH, PCR, RT-PCR and exome sequencing; expression of p53 and p21 by Western blotting.

Results: HBLAK cells proliferated for >50 passages without senescing. They expressed cytokeratins of basal urothelial cells. Terminal differentiation markers appeared only after induction of differentiation by specific protocols. The karyotype was stable, with few chromosomal changes, especially gains of chromosomes 5 and 20 and a chromosome 9p21 deletion resulting in p16^INK4A loss. A C228T TERT promoter mutation was present, but no other mutation typical of urothelial carcinoma. TP53 was wild-type and the cell cycle was arrested in response to genomic stress.

Conclusions: HBLAK cells retain some differentiation potential and respond to cytotoxic agents similar to normal urothelial cells, but contain genetic changes contributing to immortalization in urothelial tumors. HBLAK may be valuable for evaluating the tumor specificity of novel cancer drugs, but may also be applied as an urothelial in vitro carcinogenesis model.

Bladder cancer and occupational exposure to diesel and gasoline engine emissions among Canadian men

The International Agency for Research on Cancer has classified diesel exhaust as a carcinogen based on lung cancer evidence; however, few studies have investigated the effect of engine emissions on bladder cancer. The purpose of this study was to investigate the association between occupational exposure to diesel and gasoline emissions and bladder cancer in men using data from the Canadian National Enhanced Cancer Surveillance System; a population‐based case–control study. This analysis included 658 bladder cancer cases and 1360 controls with information on lifetime occupational histories and a large number of possible cancer risk factors. A job‐exposure matrix for engine emissions was supplemented by expert review to assign values for each job across three dimensions of exposure: concentration, frequency, and reliability. Odds ratios (OR) and their corresponding 95% confidence intervals were estimated using logistic regression. Relative to unexposed, men ever exposed to high concentrations of diesel emissions were at an increased risk of bladder cancer (OR = 1.64, 0.87–3.08), but this result was not significant, and those with >10 years of exposure to diesel emissions at high concentrations had a greater than twofold increase in risk (OR = 2.45, 1.04–5.74). Increased risk of bladder cancer was also observed with >30% of work time exposed to gasoline engine emissions (OR = 1.59, 1.04–2.43) relative to the unexposed, but only among men that had never been exposed to diesel emissions. Taken together, our findings support the hypothesis that exposure to high concentrations of diesel engine emissions may increase the risk of bladder cancer.

The emerging role of the androgen receptor in bladder cancer

Men are three to four times more likely to get bladder cancer than women. The gender disparity characterizing bladder cancer diagnoses has been investigated. One hypothesis is that androgen receptor (AR) signaling is involved in the etiology and progression of this disease. Although bladder cancer is not typically described as an endocrine-related malignancy, it has become increasingly clear that AR signaling plays a role in bladder tumors. This review summarizes current findings regarding the role of the AR in bladder cancer. We discuss work demonstrating AR expression in bladder cancer and its role in promoting formation and progression of tumors. Additionally, we discuss the therapeutic potential of targeting the AR in this disease.

Effect of targeted ovarian cancer therapy using amniotic fluid mesenchymal stem cells transfected with enhanced green fluorescent protein-human interleukin-2 in vivo

The aim of the present study was to investigate the effect of using amniotic fluid mesenchymal stem cells (AF-MSCs) in targeted ovarian cancer therapy in vivo. AF-MSCs were isolated from human second trimester AF and a plasmid, enhanced green fluorescent protein-human interleukin-2 (pEGFP-hIL-2) was formed. The plasmid was stably transfected into the AF-MSCs and the cells were intravenously injected into ovarian cancer nude mice models. Following stable transfection of the vector, tumor formation, and the expression and activity of hIL-2 were investigated, and microscopic pathological examinations of the tumor were performed. It was found that AF-MSCs exhibited high motility during migration in vivo, and the vector, pEGFP-hIL-2 can be stably transfected into AF-MSCs. Following stable transfection, this type of stem cell is able to successfully transport the therapeutic gene, IL-2, migrate to the ovarian cancer tumor site to secrete the functional IL-2 and treat the tumor. Thus, AF-MSCs may serve as transporters for therapeutic genes targeting ovarian tumor sites and, therefore, be involved in the treatment of tumors.

Urothelial carcinogen resistance driven by stronger Toll-like receptor 2 (TLR2) and Uroplakin III (UP III) defense mechanisms: a new model

OBJECTIVE

The objective of the study was to illustrate the applicability and significance of the novel Lewis urothelial cancer model compared to the classic Fisher 344.

METHODS

Fischer 344 and Lewis females rats, 7 weeks old, were intravesical instilled N-methyl-N-nitrosourea 1.5 mg/kg every other week for a total of four doses. After 15 weeks, animals were sacrificed and bladders analyzed: histopathology (tumor grade and stage), immunohistochemistry (apoptotic and proliferative indices) and blotting (Toll-like receptor 2-TLR2, Uroplakin III-UP III and C-Myc). Control groups received placebo.

RESULTS

There were macroscopic neoplastic lesions in 20 % of Lewis strain and 70 % of Fischer 344 strain. Lewis showed hyperplasia in 50 % of animals, normal bladders in 50 %. All Fischer 344 had lesions, 20 % papillary hyperplasia, 30 % dysplasia, 40 % neoplasia and 10 % squamous metaplasia. Proliferative and apoptotic indices were significantly lower in the Lewis strain (p < 0.01). The TLR2 and UP III protein levels were significantly higher in Lewis compared to Fischer 344 strain (70.8 and 46.5 % vs. 49.5 and 16.9 %, respectively). In contrast, C-Myc protein levels were significantly higher in Fischer 344 (22.5 %) compared to Lewis strain (13.7 %).

CONCLUSIONS

The innovative Lewis carcinogen resistance urothelial model represents a new strategy for translational research. Preservation of TLR2 and UP III defense mechanisms might drive diverse urothelial phenotypes during carcinogenesis in differently susceptible individuals.

Induction of invasive transitional cell bladder carcinoma in immune intact human MUC1 transgenic mice: a model for immunotherapy development

A preclinical model of invasive bladder cancer was developed in human mucin 1 (MUC1) transgenic (MUC1.Tg) mice for the purpose of evaluating immunotherapy and/or cytotoxic chemotherapy. To induce bladder cancer, C57BL/6 mice (MUC1.Tg and wild type) were treated orally with the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN) at 3.0 mg/day, 5 days/week for 12 weeks. To assess the effects of OH-BBN on serum cytokine profile during tumor development, whole blood was collected via submandibular bleeds prior to treatment and every four weeks. In addition, a MUC1-targeted peptide vaccine and placebo were administered to groups of mice weekly for eight weeks. Multiplex fluorometric microbead immunoanalyses of serum cytokines during tumor development and following vaccination were performed. At termination, interferon gamma (IFN-γ)/interleukin-4 (IL-4) ELISpot analysis for MUC1 specific T-cell immune response and histopathological evaluations of tumor type and grade were performed. The results showed that: (1) the incidence of bladder cancer in both MUC1.Tg and wild type mice was 67%; (2) transitional cell carcinomas (TCC) developed at a 2:1 ratio compared to squamous cell carcinomas (SCC); (3) inflammatory cytokines increased with time during tumor development; and (4) administration of the peptide vaccine induces a Th1-polarized serum cytokine profile and a MUC1 specific T-cell response. All tumors in MUC1.Tg mice were positive for MUC1 expression, and half of all tumors in MUC1.Tg and wild type mice were invasive. In conclusion, using a team approach through the coordination of the efforts of pharmacologists, immunologists, pathologists and molecular biologists, we have developed an immune intact transgenic mouse model of bladder cancer that expresses hMUC1.

Genome-wide methylation profiling and the PI3K-AKT pathway analysis associated with smoking in urothelial cell carcinoma

Urothelial cell carcinoma (UCC) is the second most common genitourinary malignant disease in the USA, and tobacco smoking is the major known risk factor for UCC development. Exposure to carcinogens, such as those contained in tobacco smoke, is known to directly or indirectly damage DNA, causing mutations, chromosomal deletion events and epigenetic alterations in UCC. Molecular studies have shown that chromosome 9 alterations and P53, RAS, RB and PTEN mutations are among the most frequent events in UCC. Recent studies suggested that continuous tobacco carcinogen exposure drives and enhances the selection of epigenetically altered cells in UCC, predominantly in the invasive form of the disease. However, the sequence of molecular events that leads to UCC after exposure to tobacco smoke is not well understood. To elucidate molecular events that lead to UCC oncogenesis and progression after tobacco exposure, we developed an in vitro cellular model for smoking-induced UCC. SV-40 immortalized normal HUC1 human bladder epithelial cells were continuously exposed to 0.1% cigarette smoke extract (CSE) until transformation occurred. Morphological alterations and increased cell proliferation of non-malignant urothelial cells were observed after 4 months (mo) of treatment with CSE. Anchorage-independent growth assessed by soft agar assay and increase in the migratory and invasive potential was observed in urothelial cells after 6 mo of CSE treatment. By performing a PCR mRNA expression array specific to the PI3K-AKT pathway, we found that 26 genes were upregulated and 22 genes were downregulated after 6 mo of CSE exposure of HUC1 cells. Among the altered genes, PTEN, FOXO1, MAPK1 and PDK1 were downregulated in the transformed cells, while AKT1, AKT2, HRAS, RAC1 were upregulated. Validation by RT-PCR and western blot analysis was then performed. Furthermore, genome-wide methylation analysis revealed MCAM, DCC and HIC1 are hypermethylated in CSE-treated urothelial cells when compared with non-CSE exposed cells. The methylation status of these genes was validated using quantitative methylation-specific PCR (QMSP), confirming an increase in methylation of CSE-treated urothelial cells compared to untreated controls. Therefore, our findings suggest that a tobacco signature could emerge from distinctive patterns of genetic and epigenetic alterations and can be identified using an in vitro cellular model for the development of smoking-induced cancer.

Selenoproteins in bladder cancer

Selenoproteins with genetically encoded selenium (Se) are very important in response to oxidative stress, redox balance and regulation of various metabolic and developmental processes. Although increased circulating Se has been associated with 33% risk reduction of bladder cancer, there are little data on selenoprotein expression at the protein and genetic level from both human and animal studies. Data from the Mammalian Gene Collection (MGC) Project clearly showed that highest mRNA expression in human urinary epithelium for TRXR1 (thioredoxin reductase 1), GPX1 (glutathione peroxidase 1), SEP15 (15 kDa selenoprotein), SELT (selenoprotein T) and SEPW1 (selenoprotein W1). Although bladder tumor has been characterized by increased Se, GPX and TRXR activity, circulating Se and GPX was interestingly decreased in these cancer patients. As such, selenoprotein expression in urinary epithelium may be involved in bladder cancer (development, progression and recurrence) and may play a significant role in chemotherapeutic intervention. Despite these findings, the role of selenoproteins in bladder cancer has rarely been investigated and the significance of selenoproteins in normal and malignant uroepithelium remains poorly understood.

In vivo and in vitro effects of RAD001 on bladder cancer

OBJECTIVE

To evaluate the influence of Everolimus (RAD001) on chemically induced urothelial lesions in mice and its influence on in vitro human bladder cancer cell lines.

METHODS

ICR male mice were given N-butyl-N-(4-hydroxybutyl) nitrosamine in drinking water for a period of 12 weeks. Subsequently, RAD001 was administered via oral gavage, for 6 weeks. At the end of the experiment, all the animals were sacrificed and tumor development was determined by means of histopathologic evaluation; mammalian target of rapamycin (mTOR) expressivity was evaluated by immunohistochemistry. Three human bladder cancer cell lines (T24, HT1376, and 5637) were treated using a range of RAD001 concentrations. MTT assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and flow cytometry were used to assess cell proliferation, apoptosis index, and cell cycle analysis, respectively. Immunoblotting analysis of 3 cell line extracts using mTOR and Akt antibodies was performed in order to study the expression of Akt and mTOR proteins and their phosphorylated forms.

RESULTS

The incidence of urothelial lesions in animals treated with RAD001 was similar to those animals not treated. RAD001 did not block T24 and HT1376 cell proliferation or induce apoptosis. A reduction in cell proliferation rate and therefore G0/G1 phase arrest, as well as a statistically significant induction of apoptosis (P = 0.001), was only observed in the 5637 cell line.

CONCLUSION

RAD001 seems not to have a significant effect on chemically induced murine bladder tumors. The effect of RAD001 on tumor proliferation and apoptosis was achieved only in superficial derived bladder cancer cell line, no effect was observed in invasive cell lines.

Human amniotic fluid-derived mesenchymal stem cells as therapeutic vehicles: a novel approach for the treatment of bladder cancer

Recent studies support cell-based therapies for cancer treatment. An advantageous cell type for such therapeutic schemes are the mesenchymal stem cells (MSCs) that can be easily propagated in culture, genetically modified to express therapeutic proteins, and exhibit an innate tropism to solid tumors in vivo. Recently, we successfully isolated and expanded MSCs from second-trimester amniotic fluid (AF-MSCs). The main characteristic of AF-MSCs is their efficient and rapid expansion in vitro. Herein, we investigated the AF-MSCs tropism and capability to transport interferon beta (IFNβ) to the region of neoplasia in a bladder tumor model. To this end, we used the T24M bladder cancer cell line, previously generated from our studies, and developed a disease progression model in immunosuppressed mice, that can recapitulate the molecular events of bladder carcinogenesis. Our results documented that AF-MSCs exhibited high motility, when migrated either to T24M cells or to T24M-conditioned medium, and we further identified and studied the secreted factors which may trigger these enhanced migratory properties. Further, lentivirus-transduced AF-MSCs, expressing green fluorescent protein (GFP) or IFNβ, were intravenously administered to T24M tumor-bearing animals at multiple doses to examine their therapeutic effect. GFP- and IFNβ-AF-MSCs successfully migrated and colonized at the tumor site. Notably, significant inhibition of tumor growth as well as prolonged survival of mice were observed in the presence of IFNβ-AF-MSCs. Collectively, these results document the great potential of AF-MSCs as anti-cancer vehicles, implemented by the targeting of the tumor site and further facilitated by their high proliferation rate and expansion efficiency in culture.

Origins of injection-site sarcomas in cats: the possible role of chronic inflammation-a review

The etiology of feline injection-site sarcomas remains obscure. Sarcomas and other tumors are known to be associated with viral infections in humans and other animals, including cats. However, the available evidence suggests that this is not the case with feline injection-site sarcomas. These tumors have more in common with sarcomas noted in experimental studies with laboratory animals where foreign materials such as glass, plastics, and metal are the causal agent. Tumors arising with these agents are associated with chronic inflammation at the injection or implantation sites. Similar tumors have been observed, albeit infrequently, at microchip implantation sites, and these also are associated with chronic inflammation. It is suggested that injection-site sarcomas in cats may arise at the administration site as a result of chronic inflammation, possibly provoked by adjuvant materials, with subsequent DNA damage, cellular transformation, and clonal expansion. However, more fundamental research is required to elucidate the mechanisms involved.

Urine from current smokers induces centrosome aberrations and spindle defects in vitro in nonmalignant human cell lines

Tobacco smoke containing numerous derived chemical carcinogens is the main risk factor for urothelial carcinoma. These carcinogens can induce DNA damage leading to chromosomal instability, which plays a fundamental role in urothelial carcinogenesis. Possible mechanisms could be centrosomal aberrations, which cause defective spindles and may be responsible for genetic instability. We evaluated the effect of urine from never smokers (NS) and current smokers (CS) in concentrations of 0 to 50% on cell proliferation, chromosomes, centrosomes, and the spindle status of normal human dermal fibroblasts and normal human urothelial cells (UROtsa). After 2 weeks of urine treatment, cell cultures were analyzed by centrosome and spindle immunostaining and conventional cytogenetics. Effects were compared to results of untreated controls. Analysis of normal human dermal fibroblasts and UROtsa cells revealed that urine from CS induced higher values of centrosome aberrations in a dose-dependent and cell line-independent manner when compared to cultures treated with urine from NS and untreated controls. Centrosomal alterations correlated with spindle defects and an increase of sporadic chromosomal aberrations. The observations suggest a causative role of chemical carcinogens in urine from CS in the origin of centrosome and spindle defects in vitro leading to chromosomal instability and may be involved in urothelial carcinogenesis.

Organotypic and 3D reconstructed cultures of the human bladder and urinary tract

Three-dimensional organotypic cultures of human urinary tract tissue have been established as intact and reconstituted tissues, with the latter generated by combining cultured normal human urothelial (NHU) cells with an appropriate stroma. Organoids may be maintained at an air-liquid interface in static culture for periods of up to 20 weeks, with analysis by immunohistology for expression of urothelial differentiation-associated markers providing a qualitative, but objective assessment criterion. Where reconstructed using bladder cancer cell lines, the resultant organoids recapitulate the invasive characteristics of the originating tumour, but the need to use authenticated cell line stocks is emphasised. The organoid approach represents an important tool for investigating urothelial-stromal cell interactions during homeostasis and disease, and for testing bladder tissue engineering and reconstructive strategies. Potential future developments of the technique are discussed and include genetic manipulation of the urothelial cells to generate disease models and incorporation of biomaterial scaffolds to support artificial stroma development.

Use of fluorescein isothiocyanate-human serum albumin for the intravesical photodiagnosis of non-muscle-invasive bladder cancer: an in vitro study using multicellular spheroids composed of normal human urothelial and urothelial cell carcinoma cell lines

OBJECTIVE

• To evaluate human serum albumin (HSA), fluorescently labelled with fluorescein isothiocyanate (FITC), as a potential intravesical photodiagnostic method for the early detection of non-muscle-invasive bladder cancer.

PATIENTS AND METHODS

• By using multicellular spheroids prepared from normal human urothelial (NHU) cells and from different urothelial cell carcinoma (UCC) cell lines (T24, J82), we simulated three-dimensionally the normal urothelium and non-muscle-invasive UCCs present in the bladder of patients. • The distribution of FITC-HSA in these spheroids was investigated.

RESULTS

• Our data showed that fluorescently labelled albumin is quite evenly dispersed throughout the spheroids. However, in the case of the 10 mg/mL incubations, the fluorescence intensity seems to increase slightly towards the spheroid core. • Using 1 mg/mL, the penetration of FITC-HSA in T24 differed significantly from the penetration in NHU spheroids, but this was not the case for J82 spheroids. • When the concentration of FITC-HSA was increased 10-fold, all UCC spheroids exhibited a significantly different accumulation of FITC-HSA.

CONCLUSIONS

• As spheroids represent a suitable in vitro model for predicting the in vivo behaviour of compounds, our data suggest that FITC-HSA could be used for the early detection of non-muscle-invasive bladder cancer. • Human serum albumin conjugates of new or already available intravesical drugs could be generated to create alternative bladder cancer therapies with increased selectivity.

Differential regulation of growth-promoting signalling pathways by E-cadherin

BACKGROUND

Despite the well-documented association between loss of E-cadherin and carcinogenesis, as well as the link between restoration of its expression and suppression of proliferation in carcinoma cells, the ability of E-cadherin to modulate growth-promoting cell signalling in normal epithelial cells is less well understood and frequently contradictory. The potential for E-cadherin to co-ordinate different proliferation-associated signalling pathways has yet to be fully explored.

METHODOLOGY/PRINCIPAL FINDINGS

Using a normal human urothelial (NHU) cell culture system and following a calcium-switch approach, we demonstrate that the stability of NHU cell-cell contacts differentially regulates the Epidermal Growth Factor Receptor (EGFR)/Extracellular Signal-Regulated Kinase (ERK) and Phosphatidylinositol 3-Kinase (PI3-K)/AKT pathways. We show that stable cell contacts down-modulate the EGFR/ERK pathway, whilst inducing PI3-K/AKT activity, which transiently enhances cell growth at low density. Functional inactivation of E-cadherin interferes with the capacity of NHU cells to form stable calcium-mediated contacts, attenuates E-cadherin-mediated PI3-K/AKT induction and enhances NHU cell proliferation by allowing de-repression of the EGFR/ERK pathway and constitutive activation of β-catenin-TCF signalling.

CONCLUSIONS/SIGNIFICANCE

Our findings provide evidence that E-cadherin can differentially and concurrently regulate specific growth-related signalling pathways in a context-specific fashion, with direct, functional consequences for cell proliferation and population growth. Our observations not only reveal a novel, complex role for E-cadherin in normal epithelial cell homeostasis and tissue regeneration, but also provide the basis for a more complete understanding of the consequences of E-cadherin loss on malignant transformation.

Cell damage and death by autoschizis in human bladder (RT4) carcinoma cells resulting from treatment with ascorbate and menadione

A human bladder carcinoma cell line RT4 was sham-treated with buffer or treated with ascorbate (VC) alone, menadione alone (VK(3)), or a combination of ascorbate:menadione (VC+VK(3)) for 1, 2, and 4 h. Cytotoxic damage was found to be treatment-dependent in this sequence: VC+VK(3)>VC>VK(3)>sham. The combined treatment induced the greatest oxidative stress, with early tumor cell injury affecting the cytoskeletal architecture and contributing to the self-excisions of pieces of cytoplasm freed from organelles. Additional damage, including a reduction in cell size, organelle alterations, nuclear damage, and nucleic acid degradation as well as compromised lysosome integrity, is caused by reactivation of DNases and the redox cycling of VC or VC+VK(3). In addition, cell death caused by VC+VK(3) treatment as well as by prolonged VC treatment is consistent with cell demise by autoschizis, not apoptosis. This report confirms and complements previous observations about this new mode of tumor cell death. It supports the contention that a combination of VC+VK(3), also named Apatone, could be co-administered as a nontoxic adjuvant with radiation and/or chemotherapies to kill bladder tumor cells and other cancer cells without any supplementary risk or side effects for patients.

Evolution on experimental animal model for upper urothelium carcinogenesis

PURPOSE

No optimal, well designed and reproducible animal model for upper urothelial carcinogenesis exists. This study characterized the histopathological features on top of immunolocalization of alpha-dystroglycans (alpha-DG) and matrix metalloproteinase (MMP-9) and cell turn-over in the upper urinary tract using a novel experimental model.

METHODS

Seventy-five female Fischer 344 rats were divided into three groups: the control group received a 0.30-ml dose of 0.9% physiological saline; the MNU group (chemical carcinogen N-methyl-N-nitrosourea) received 0.30 ml of MNU; and the MNU-citrate group received 0.30 ml of MNU plus sodium citrate, every one intravesically every other week for a total of 4 doses. After 15 weeks, bladder, ureters and renal pelvis were collected for morphological and molecular analysis.

RESULTS

Associated management with MNU and sodium citrate was able to lead to 100% of both urinary bladder and upper urinary tract tumors, being the high-grade noninvasive papillary urothelial carcinoma the most frequent lesion. The upper urothelium showed reduced alpha-DG and increased MMP-9 and Ki-67 immunoreactivities in the MNU-citrate group in relation to the other groups. MNU group presented no upper urothelium tumor and 100% bladder tumor.

CONCLUSIONS

This is a relevant evolution on experimental animal model for upper urinary tract carcinogenesis field. MMP-dependent disruption of the DG complex plays an important role in urothelial tumor carcinogenesis and showed the model applicability and significance. MNU-citrate model could contribute to a better understanding of human upper urothelial cancer development as well as to its local treatment strategies in a near future.

Biological similarities between murine chemical-induced and natural human bladder carcinogenesis

The present study investigated the similarities between rodent and human urothelial carcinogenesis models using DNA content, p53 and Ki-67 immunoexpression as surrogate markers of bladder carcinogenesis. Following N-butyl-N-(4-hydroxybutyl)-nitrosamine exposure, 49 human cystectomy specimens of bladder cancer and 53 rat bladder specimens were studied. All of the tumours and adjacent mucosa present in each specimen were evaluated. High similarities were observed between the rodent urothelium carcinogenesis process and the corresponding process in humans, in regards to the histopathological features and biological alteration profile: DNA aneuploidy, p53 overexpression and high proliferative index measured by Ki-67 immunoexpression. Despite these similarities, a higher frequency of alterations was observed in earlier stages in the rat chemical-induced carcinogenesis, namely in 5c aneuploid cells, p53 overexpression and higher Ki-67 labelling index. These results confirm that this experimental animal model is a suitable and reproducible model of bladder carcinogenesis, particularly in regards to high-risk non-invasive and invasive urothelial carcinomas. These features mandate its use in the identification of new molecular targets and evaluation of tumour response to new cytotoxic drugs or drug combinations in bladder cancer therapeutic intervention.

Key concerns about the current state of bladder cancer: a position paper from the Bladder Cancer Think Tank, the Bladder Cancer Advocacy Network, and the Society of Urologic Oncology

Bladder cancer is the fifth most common cancer in the United States and, on a per capita basis, is the most expensive cancer from diagnosis to death. Unfortunately, National Cancer Institute funding for bladder cancer is quite low when compared with other common malignancies. Limited funding has stifled research opportunities for new and established investigators, ultimately encouraging them to redirect research efforts to other organ sites. Waning interest of scientists has further fueled the cycle of modest funding for bladder cancer. One important consequence of this has been a lack of scientific advancement in the field. Patient advocates have decidedly advanced research efforts in many cancer sites. Breast, prostate, pancreatic, and ovarian cancer advocates have organized highly successful campaigns to lobby the federal government and the medical community to devote increased attention and funding to understudied malignancies and to conduct relevant studies to better understand the therapy, diagnosis, and prevention of these diseases. Bladder cancer survivors have lacked a coordinated advocacy voice until recently. A concerted effort to align bladder cancer advocates, clinicians, and urologic organizations is essential to define the greatest needs in bladder cancer and to develop related solutions. This position paper represents a collaborative discussion to define the most concerning trends and greatest needs in the field of bladder cancer as outlined by the Bladder Cancer Think Tank, the Bladder Cancer Advocacy Network, and the Society of Urologic Oncology.

Three clonal types of urothelium with different capacities for replication

OBJECTIVES

Similar to other epithelia, urothelium in vivo has a hierarchal organization of cells each with specific gradients of differentiation. While distinct cell types have been described as important in bladder cancer in vitro, clonal and proliferative capacities of normal urothelial cells have not been characterized.

MATERIALS AND METHODS

Three cell types and colony types were identified from primary porcine urothelial culture. Proliferative activity, patterns of apoptosis and differentiation, colony forming efficiency and ability to change phenotype with passage were determined and compared.

RESULTS

Small, T-I colonies with large flattened (type-1) cells had low levels of proliferation and high levels of apoptosis. Large T-III colonies had a central area of small (type-3) cells surrounded by type-1 and type-2 cells. Proliferation and apoptosis were asymmetrically distributed in the periphery of T-II and T-III colonies. T-III colonies proved to be significantly more clonogenic and proliferative. With appropriate induction, type-1 cells were able to proliferate upon passage and form type-3 cells, yet long-term culture demonstrated that progeny of type-1 cells appeared to have inherited a clonogenic handicap.

CONCLUSIONS

Type-3 cells in the centre of T-III colonies appear to harbour stem-like qualities with a relatively low proliferative and apoptotic index at homeostasis and the ability to become highly proliferative upon passage. This study demonstrates that distinct urothelial cell types with differing clonal capacities can be isolated from the bladder and these cells may have implications for tissue engineering and carcinogenesis.

Rat Urinary Bladder Carcinogenesis by Dual-Acting PPARalpha + gamma Agonists

Despite clinical promise, dual-acting activators of PPARalpha and gamma (here termed PPARalpha+gamma agonists) have experienced high attrition rates in preclinical and early clinical development, due to toxicity. In some cases, discontinuation was due to carcinogenic effect in the rat urothelium, the epithelial layer lining the urinary bladder, ureters, and kidney pelvis. Chronic pharmacological activation of PPARalpha is invariably associated with cancer in rats and mice. Chronic pharmacological activation of PPARgamma can in some cases also cause cancer in rats and mice. Urothelial cells coexpress PPARalpha as well as PPARgamma, making it plausible that the urothelial carcinogenicity of PPARalpha+gamma agonists may be caused by receptor-mediated effects (exaggerated pharmacology). Based on previously published mode of action data for the PPARalpha+gamma agonist ragaglitazar, and the available literature about the role of PPARalpha and gamma in rodent carcinogenesis, we propose a mode of action hypothesis for the carcinogenic effect of PPARalpha+gamma agonists in the rat urothelium, which combines receptor-mediated and off-target cytotoxic effects. The proposed mode of action hypothesis is being explored in our laboratories, towards understanding the human relevance of the rat cancer findings, and developing rapid in vitro or short-term in vivo screening approaches to faciliate development of new dual-acting PPAR agonist compounds.

[Bladder carcinoma cell lines as models of the pathobiology of bladder cancer. Review of the literature and establishment of a new progression series]

BACKGROUND

Tumour cell lines represent valuable preclinical models to decipher underlying biology and identify potential therapy targets and pharmacologically useful compounds. Approximately 50 human bladder cancer cell lines have been established to date, mainly from invasive and metastatic tumours. Two of these, namely T24 and 253J, were experimentally further developed into progression series. These models have provided important insights into later tumour progression events and metastatic dissemination. Only a few cell lines are available as models of non-invasive papillary bladder cancer and no progression series have yet been established.

MATERIAL AND METHODS

During the course of establishing a doxorubicin-resistant variant cell line of the human papillary bladder carcinoma cell line BFTC-905, a unique cell colony was identified, apparently involving cells with divergent growth patterns. Subsequent subculturing yielded three daughter cell lines, BFTC-905-compact, BFTC-905-diffuse und BFTC-905-diffuse M. Their fundamental characterization included basic cell morphology, cell membrane expression of E-Cadherin, karyotype analysis, invasion and colony forming capacity in soft agar. The clonal origin of the newly established daughter cell lines was assessed by means of molecular genetic methods.

RESULTS

We could identify important differences in multiple transformation related traits among the cell lines of the BFTC-905 progression series. Both diffuse cell lines (BFTC-905-diffuse und BFTC-905-diffuse M) differed from the BFTC-905-compact cell line by growing in a less organized,"diffuse" manner, which involved colonies of cells exhibiting apparently normal cell-to-cell adhesion as well as individual cells outside of them. This diminution of the cell-to-cell adhesion was accompanied by a corresponding decrease of membranous E-Cadherin. The BFTC-905-diffuse M cell line displayed a dramatic increase in the overall chromosome number, resulting in a hypertetraploid karyotype. At the same time, this cell line, as the only one in the progression series, acquired the ability to grow independent of anchorage in soft agar. All three cell lines remained noninvasive. Allelic distribution of highly polymorphic DNA-markers in the cell lines of the BFTC-905 progression series provided unequivocal evidence of their common origin.

CONCLUSION

The newly established BFTC-905 progression series manifests two aspects of the early progression of non-invasive bladder carcinoma, not exhibited by any other progression series published so far, namely dynamic changes in the expression of E-Cadherin and a complex karyotypic evolution. It may thus contribute important insights into further understanding of the pathobiology of bladder cancer.

Topical chemotherapy in human urothelial carcinoma explants: a novel translational tool for preclinical evaluation of experimental intravesical therapies

BACKGROUND

Urothelial carcinoma (UC) is associated with a high local recurrence rate despite intravesical therapy. There is a lack of representative preclinical models for standardized testing of novel experimental therapies.

OBJECTIVE

To develop an ex vivo model for human UC and to evaluate its ability to generate reproducible and reliable results when testing cytotoxic agents.

DESIGN, SETTING, AND PARTICIPANTS

Normal human urothelium (NHU) and bladder UC explants were collected from patients treated at our institution. A total of 195 surgical explants were cultured on a gelatine matrix. Tissue viability was regularly assessed using nicotinamide adenine dinucleotide (NADH) diaphorase enzymehistochemistry. Topical paclitaxel (PTX) or mitomycin C (MMC) chemotherapy was performed in a subset of 45 UC specimens.

INTERVENTION

All patients underwent radical cystectomy (RC) or primary transurethral resection (TUR) of a bladder UC.

MEASUREMENTS

Triple immunofluorescence (pan-cytokeratin [pan-CK]; 4',6-diamidin-2'-phenylindol-dihydrochloride [DAPI]; terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling [TUNEL]) and caspase-3 staining of paraffin sections was performed. Proliferation rates were assessed using Ki-67 labelling indices. Apoptosis (percent) was quantified in representative tissue areas to characterize culture stability and to assess antineoplastic effects.

RESULTS AND LIMITATIONS

No signs of necrosis and no significant changes in apoptosis were observed during the first 12 d of culture. Of all explants, 88.5% were vital after 20 d. In a highly reproducible fashion, topical chemotherapy resulted in significantly increased apoptosis (37.4% [19.0-75.0%] for PTX and 36.2% [18.8-46.7%] for MMC) compared with controls (7.5% [3.0-26.8%]; p<0.001]). No statistically significant difference was observed regarding the effects of the two chemotherapeutic agents (p=0.119).

CONCLUSIONS

The presented human ex vivo model takes UC heterogeneity into account and serves as a valuable translational tool. It offers an attractive alternative to preclinical cell line experiments or animal models and may even be used for prospective toxicity and drug efficacy tests in individual patients.

Intravesical chemotherapy of high-grade bladder cancer with HTI-286, a synthetic analogue of the marine sponge product hemiasterlin

PURPOSE

HTI-286 is a fully synthetic analogue of the natural tripeptide hemiasterlin that inhibits tubulin polymerization and has strong cytotoxic potential. In this study, we evaluate the inhibitory effects of HTI-286 on human bladder cancer growth, both in vitro and as an intravesical agent in an orthotopic murine model.

EXPERIMENTAL DESIGN

Various bladder cancer cell lines were treated with HTI-286 and mitomycin C (MMC) in vitro. Human KU-7 bladder tumor cells that stably express firefly luciferase were inoculated in female nude mice by intravesical instillation and quantified using bioluminescence imaging. Mice with established KU-7-luc tumors were given HTI-286 or MMC intravesically twice a week for 2 h. Pharmacokinetic data was obtained using high-performance liquid chromatography-mass spectrometry analyses.

RESULTS

In vitro, HTI-286 was a potent inhibitor of proliferation in all tested cell lines and induced marked increases in apoptosis of KU-7-luc cells even after brief exposure. In vivo, HTI-286 significantly delayed cancer growth of bladder tumors in a dose-dependent fashion. HTI-286, at a concentration of 0.2 mg/mL, had comparable strong cytotoxicity as 2.0 mg/mL of MMC. The estimated systemic bioavailability of intravesically given HTI-286 was 1.5% to 2.1% of the initial dose.

CONCLUSIONS

Intravesical HTI-286 instillation therapy showed promising antitumor activity and minimal toxicity in an orthotopic mouse model of high-grade bladder cancer. These findings provide preclinical proof-of-principle for HTI-286 as an intravesical therapy for nonmuscle-invasive bladder cancer and warrant further evaluation of efficacy and safety in early-phase clinical trials.

Primary cultures of human urothelial cells for genotoxicity testing

A cell culture system with human-derived urothelial cells was established based upon previous experience with cultures of porcine urinary bladder epithelial cells. Human tissue specimens used were derived from urinary bladders (n = 17) or ureters (n = 50) of patients undergoing urological operations. The epithelial origin and differentiation status was evaluated by an immunohistochemical staining for cytokeratins 7, 8, 18, 19, and 20 for isolated and cultured cells. Specimens from human ureters were better suited for primary cell cultures of the urothelium than specimens from human urinary bladders. Successful attachment and proliferation were reached by 98% of the ureter specimens (urinary bladder: 71%) and confluency was reached by 78% of the ureter cultures (urinary bladder: 18%). In the first 14 d of culture the cytokeratin patterns of cultured cells were comparable to those of native mucosa cells. During prolonged cell culture the cytokeratin patterns of the human urothelial cells (HUC) changed into a beginning dedifferentiation: Cytokeratin (CK) 18 was only detectable in cell cultures cultured for more than 29 d, whereas CK 19 was not detectable at d 29. Cell cultures of primary human urothelial cells may be used for in vitro testing of cytotoxic or genotoxic effects.

A new and reliable culture system for superficial low-grade urothelial carcinoma of the bladder

Several bladder cancer culture systems have been developed in recent years. However, reports about successful primary cultures of superficial urothelial carcinomas (UC) are sparse. Based on the specific growth requirements of UC described previously, we developed a new and reliable culture system for superficial low-grade UC. Between November 2002 and April 2006, 64 primary cultures of bladder cancer specimens were performed. After incubating the specimens overnight in 0.1% ethylenediaminetetraacetic acid solution, tumour cells could easily be separated from the submucosal tissue. Subsequently, cells were seeded in a low-calcium culture medium supplemented with 1% serum, growth factors, non-essential amino acids and glycine. The malignant origin of the cultured cells was demonstrated by spectral karyotyping. Overall culture success rate leading to a homogenous tumour cell population without fibroblast contamination was 63%. Culture success could be remarkably enhanced by the addition of glycine to the culture medium. Interestingly, 86.4% of pTa tumours were cultured successfully compared to only 50% of the pT1 and 38% of advanced stage tumours, respectively. G1 and G2 tumours grew significantly better than G3 tumours (86, 73 and 41%, respectively). Up to three passages of low-grade UC primary cultures were possible. We describe a new and reliable culture system, which is highly successful for primary culture and passage of low-grade UC of the bladder. Therefore, this culture system can widely be used for functional experiments on early stage bladder cancer.