Human bladder cancer: evidence for a potential irritation-induced mechanism

ICH S1 prospective evaluation study and weight of evidence assessments: commentary from industry representatives

Industry representatives on the ICH S1B(R1) Expert Working Group (EWG) worked closely with colleagues from the Drug Regulatory Authorities to develop an addendum to the ICH S1B guideline on carcinogenicity studies that allows for a weight-of-evidence (WoE) carcinogenicity assessment in some cases, rather than conducting a 2-year rat carcinogenicity study. A subgroup of the EWG composed of regulators have published in this issue a detailed analysis of the Prospective Evaluation Study (PES) conducted under the auspices of the ICH S1B(R1) EWG. Based on the experience gained through the Prospective Evaluation Study (PES) process, industry members of the EWG have prepared the following commentary to aid sponsors in assessing the standard WoE factors, considering how novel investigative approaches may be used to support a WoE assessment, and preparing appropriate documentation of the WoE assessment for presentation to regulatory authorities. The commentary also reviews some of the implementation challenges sponsors must consider in developing a carcinogenicity assessment strategy. Finally, case examples drawn from previously marketed products are provided as a supplement to this commentary to provide additional examples of how WoE criteria may be applied. The information and opinions expressed in this commentary are aimed at increasing the quality of WoE assessments to ensure the successful implementation of this approach.

A machine learning-based nomogram model for predicting the recurrence of cystitis glandularis

Background

Cystitis glandularis is a chronic inflammatory disease of the urinary system characterized by high recurrence rates, the reasons for which are still unknown.

Objectives

This study aims to identify potential factors contributing to recurrence and propose a simple and feasible prognostic model through nomogram construction.

Design

Patients with confirmed recurrence based on outpatient visits or readmissions were included in this study, which was subsequently divided into training and validation cohorts.

Methods

Machine learning techniques were utilized to screen for the most important predictors, and these were then employed to construct the nomogram. The reliability of the nomogram was assessed through receiver operating characteristic curve analysis, decision curve analysis, and calibration curves.

Results

A total of 252 patients met the screening criteria and were enrolled in this study. Over the 12-month follow-up period, the relapse rate was found to be 57.14% (n = 144). The five final predictors identified through machine learning were urinary infections, urinary calculi, eosinophil count, lymphocyte count, and serum magnesium. The area under curve values for all three time points assessing recurrence exceeded 0.75. Furthermore, both calibration curves and decision curve analyses indicated good performance of the nomogram.

Conclusion

We have developed a reliable machine learning-based nomogram for predicting recurrence in cystitis glandularis.

Characterisation of tumour-immune phenotypes and PD-L1 positivity in squamous bladder cancer

AIMS

Immune checkpoint inhibitor (ICI) therapy has become a viable treatment strategy in bladder cancer. However, treatment responses vary, and improved biomarkers are needed. Crucially, the characteristics of immune cells remain understudied especially in squamous differentiated bladder cancer (sq-BLCA). Here, we quantitatively analysed the tumour-immune phenotypes of sq-BLCA and correlated them with PD-L1 expression and FGFR3 mutation status.

METHODS

Tissue microarrays (TMA) of n = 68 non-schistosomiasis associated pure squamous cell carcinoma (SCC) and n = 46 mixed urothelial carcinoma with squamous differentiation (MIX) were subjected to immunohistochemistry for CD3, CD4, CD8, CD56, CD68, CD79A, CD163, Ki67, perforin and chloroacetate esterase staining. Quantitative image evaluation was performed via digital image analysis.

RESULTS

Immune infiltration was generally higher in stroma than in tumour regions. B-cells (CD79A) were almost exclusively found in stromal areas (sTILs), T-lymphocytes and macrophages were also present in tumour cell areas (iTILs), while natural killer cells (CD56) were nearly missing in any area. Tumour-immune phenotype distribution differed depending on the immune cell subset, however, hot tumour-immune phenotypes (high density of immune cells in tumour areas) were frequently found for CD8 + T-cells (33%), especially perforin + lymphocytes (52.2%), and CD68 + macrophages (37.6%). Perforin + CD8 lymphocytes predicted improved overall survival in sq-BLCA while high PD-L1 expression (CPS ≥ 10) was significantly associated with higher CD3 + , CD8 + and CD163 + immune cell density and high Ki67 (density) of tumour cells. Furthermore, PD-L1 expression was positively associated with CD3 + /CD4 + , CD3 + /CD8 + and CD68 + /CD163 + hot tumour-immune phenotypes. FGFR3 mutation status was inversely associated with CD8 + , perforin + and CD79A + lymphocyte density.

CONCLUSIONS

Computer-based image analysis is an efficient tool to analyse immune topographies in squamous bladder cancer. Hot tumour-immune phenotypes with strong PD-L1 expression might pose a promising subgroup for clinically successful ICI therapy in squamous bladder cancer and warrant further investigation.

Bacteria in Carcinogenesis and Cancer Prevention: A Review Study

Context: Although conventional therapies improve the conditions of patients with cancer, adverse side effects, and resistance to different therapies have convinced scientists to use alternative methods to overcome these problems. One of the most promising research directions is the application of specific types of bacteria and their components to prevent and treat different cancers. Apart from the ability of bacteria to modulate immune responses, various particular properties such as toxin production and anaerobic lifestyle, have made them one of the potential candidates to help cancer therapy. Evidence Acquisition: In this review, the latest information on the role of bacteria in carcinogenesis and cancer prevention in PubMed, Google scholar, and Science Direct databases in 2020 were considered using a combination of keywords “bacteria”, “carcinogenesis”, “cancer” and “prevention”. Results: Bacteria-cancer interactions can be studied in 2 areas of bacteria and carcinogenesis and the other bacteria and cancer treatment or prevention. In this review, bacterial carcinogenicity has been mentioned with 3 main mechanisms: bacterial toxin, bacterial metabolites, and chronic inflammation caused by bacteria. Bacterial-mediated tumor therapy (BMTT) is briefly discussed in 8 mechanisms including tumor-targeting bacterial therapy, gene therapy and vectors, bacterial products, arginine metabolism, magnetotactic bacteria, combination bacteriolytic therapy (COBALT), immunomodulation of bacteria in cancer, and immune survival. Conclusions: The importance of bacteria in terms of diversity in their interaction with humans, as well as their components that can affect homeostasis and the immune system, has made them a powerful factor in describing the human condition in health and disease. These important elements can be used in the prevention and treatment of many complex diseases with different origins like cancer. The present study can provide an overview of the role of bacteria in cancer development or prevention and potential approaches for bacteria in cancer therapy.

Risk Assessment in the Genomic Era

The sequencing of the human and mouse genomes, and soon that of the rat, offers a foundation to evaluate biological phenomena, including toxicologic effects. Numerous tools are being developed to evaluate aspects of biology based on the DNA sequence. These tools can be utilized to evaluate absorption, distribution, metabolism and excretion, and effects of the toxicologically active product on the target organ. The genes involved can be broadly categorized as those affecting susceptibility to a toxicologic effect and those that are involved in the biologic response. For risk assessment to be performed in a rational manner, fundamental mechanisms of toxicologic processes must be ascertained. Based on successes already achieved, such as development of transgenic and knockout mouse strains, the application of aspects of the genomics revolution could be useful in developing a better understanding of mechanisms, and possibly in identifying specific markers of responses. In addition, genomics are likely to be useful in translating effects between species. However, genomics are being portrayed as the ultimate solution to all of toxicology. This is hardly the case. Basic chemistry, biochemistry, toxicokinetics, pharmacology, and pathology will continue to be needed in the overall weight of evidence approach to risk assessment. Genomics are likely to be of limited usefulness in predicting individual, in contrast to population susceptibility to various toxicological responses. Concordance of various diseases in identical twins, for example, different cancers, is rarely greater than 20% over the lifetime of these individuals. Similarly, genomics are likely to be of limited usefulness in screening for toxicologic end points. As with other tools of biology, those to be developed based on the genome are likely to provide greater usefulness in dissecting the mechanistic processes involved and defining the basis for susceptibility.

Nonkeratinised squamous metaplasia of the urinary bladder in children: a report of case experiences

Background. Squamous metaplasia refers to the pathological transformation of the urothelium leading to nonkeratinised stratified squamous metaplasia (N-KSM). Objective. To present our experiences in the diagnosis and treatment of N-KSM of the urinary bladder in children. Materials and Methods. In this study, we present our experiences in the diagnosis and treatment of N-KSM of the urinary bladder in children aged from 5 to 17 years. From 2005 to 2013, metaplasia was diagnosed in 119 patients. The reasons behind visiting the hospital were nonspecific intense pain in the abdomen, recurrent urinary tract infections, and urination disorders. The most common symptoms of urinary bladder dysfunction were pollakiuria and difficulties in initiating micturition and retention of urine (reduced detrusor muscle activity). Results. In 20/119 patients (16.8%), metaplasia was incidentally diagnosed during cystoscopy performed for other causes. The changes characteristic for squamous metaplasia were diagnosed—in all these patients, a biopsy was performed. In all 119 patients, a squamous metaplasia was histopathologically diagnosed. Conclusions. Squamous metaplasia of the urinary bladder mucosa occurs in children and adolescents. Symptomatic treatment is administered mainly to improve the patients' quality of life and disease prognosis.

Crosstalk among dietary polyunsaturated fatty acids, urolithiasis, chronic inflammation, and urinary tract tumor risk

Based on a consistent bulk of experimental and epidemiologic works, we proposed that abnormal metabolism and/or dietary deprivation of essential polyunsaturated fatty acids by inducing a chronic and subclinical essential fatty acid deficiency (EFAD) in urothelial cell membranes may enhance the risk for urinary tract tumor (UTT) development. This threat may be enhanced by the unusual fact that the fatty-acid profile of the normal urothelium is similar to that reported in EFAD. The risk for UTT may be worsened when coexisting with a low-grade chronic inflammation (LGCI) state induced by urolithiasis or disbalance management of peroxides, free radical molecules, and their quenchers. There is cumulative evidence linking the LGCI of the urinary tract mucosa, calculi, and UTT, due to the long-standing release of promitotic, promutagen, and pro-inflammatory antiapoptotic cytokines in these conditions. The dual role played by pro- and anti-inflammatory eicosanoids and bioactive lipids, cytokines, and the disbalance of lipid peroxidation is discussed, concluding that the moderate, long-standing consumption or dietary supplementation of ω-3 PUFAs may improve the chances of avoiding UTT development.

A case-control study on the association between bladder cancer and prior bladder calculus

Background

Bladder calculus is associated with chronic irritation and inflammation. As there is substantial documentation that inflammation can play a direct role in carcinogenesis, to date the relationship between stone formation and bladder cancer (BC) remains unclear. This study aimed to examine the association between BC and prior bladder calculus using a population-based dataset.

Methods

This case–control study included 2,086 cases who had received their first-time diagnosis of BC between 2001 and 2009 and 10,430 randomly selected controls without BC. Conditional logistic regressions were employed to explore the association between BC and having been previously diagnosed with bladder calculus.

Results

Of the sampled subjects, bladder calculus was found in 71 (3.4%) cases and 105 (1.1%) controls. Conditional logistic regression analysis revealed that the odds ratio (OR) of having been diagnosed with bladder calculus before the index date for cases was 3.42 (95% CI = 2.48-4.72) when compared with controls after adjusting for monthly income, geographic region, hypertension, diabetes, coronary heart disease, and renal disease, tobacco use disorder, obesity, alcohol abuse, and schistosomiasis, bladder outlet obstruction, and urinary tract infection. We further analyzed according to sex and found that among males, the OR of having been previously diagnosed with bladder calculus for cases was 3.45 (95% CI = 2.39-4.99) that of controls. Among females, the OR was 3.05 (95% CI = 1.53-6.08) that of controls.

Conclusions

These results add to the evidence surrounding the conflicting reports regarding the association between BC and prior bladder calculus and highlight a potential target population for bladder cancer screening.

Peroxisome proliferator-activated receptor agonists and bladder cancer: lessons from animal studies

This article reviews available animal studies on the possible link between the use of peroxisome proliferator-activated receptor (PPAR) agonists and bladder cancer, with further discussion on the possible implications to humans. Carcinogenicity studies suggest that the PPARγ agonist pioglitazone and dual PPARα/γ agonists such as ragaglitazar, muraglitazar, and naveglitazar may increase the risk of bladder cancer in a dose-responsive pattern in rats. It is interesting that bladder cancer related to PPAR agonists shows remarkable species- and sex-specificity and has a predilection to occur in the ventral dome of bladder in rodents. While male rats treated with pioglitazone or muraglitazar have a higher propensity to develop bladder cancer than female rats, mice of both sexes do not develop bladder cancer even when exposed to very high doses. Direct genotoxicity or cytotoxicity of PPAR agonists is unlikely to be the mode of action because most of the parent compounds or their metabolites of the PPAR agonists are neither mutagenic nor genotoxic, and they are rarely excreted in the urine; but a receptor-mediated PPAR effect cannot be excluded. Some suggest a "urolithiasis hypothesis" referring to the formation of urinary solids and calculi, which subsequently causes bladder necrosis, regenerative proliferation, hypertrophy, and cancer. However, whether these animal findings could have human relevance is not yet fully understood. Some argue that the urolithiasis-induced bladder cancer might be rat-specific and would probably not be applicable to humans. An effect of increased urinary growth factors induced by PPAR agonists has also been proposed, but this requires more investigations. Before fully clarified, a balance between the risks and benefits of the use of pioglitazone, an approved oral antidiabetic agent that has recently been linked to an increased but not yet confirmed risk of bladder cancer in humans, should be justified for individual use.

Urinary bladder cancer risk factors in Egypt: a multicenter case-control study

BACKGROUND

We investigated associations between tobacco exposure, history of schistosomiasis, and bladder cancer risk in Egypt.

METHODS

We analyzed data from a case-control study (1,886 newly diagnosed and histologically confirmed cases and 2,716 age-, gender-, and residence-matched, population-based controls). Using logistic regression, we estimated the covariate-adjusted ORs and 95% confidence interval (CI) of the associations.

RESULTS

Among men, cigarette smoking was associated with an increased risk of urothelial carcinoma (OR = 1.8; 95% CI, 1.4-2.2) but not squamous cell carcinoma (SCC); smoking both water pipes and cigarettes was associated with an even greater risk for urothelial carcinoma (OR = 2.9; 95% CI, 2.1-3.9) and a statistically significant risk for SCC (OR = 1.8; 95% CI, 1.2-2.6). Among nonsmoking men and women, environmental tobacco smoke exposure was associated with an increased risk of urothelial carcinoma. History of schistosomiasis was associated with increased risk of both urothelial carcinoma (OR = 1.9; 95% CI, 1.2-2.9) and SCC (OR = 1.9; 95% CI, 1.2-3.0) in women and to a lesser extent (OR = 1.4; 95% CI, 1.2-1.7 and OR = 1.4; 95% CI, 1.1-1.7, for urothelial carcinoma and SCC, respectively) in men.

CONCLUSIONS

The results suggest that schistosomiasis and tobacco smoking increase the risk of both SCC and urothelial carcinoma.

IMPACT

This study provides new evidence for associations between bladder cancer subtypes and schistosomiasis and suggests that smoking both cigarettes and water pipes increases the risk for SCC and urothelial carcinoma in Egyptian men.

Toxicological review and oral risk assessment of terephthalic acid (TPA) and its esters: A category approach

Polyethylene terephthalate, a copolymer of terephthalic acid (TPA) or dimethyl terephthalate (DMT) with ethylene glycol, has food, beverage, and drinking water contact applications. Di-2-ethylhexyl terephthalate (DEHT) is a plasticizer in food and drinking water contact materials. Oral reference doses (RfDs) and total allowable concentrations (TACs) in drinking water were derived for TPA, DMT, and DEHT. Category RfD and TAC levels were also established for nine C(1)-C(8) terephthalate esters. The mode of action of TPA, and of DMT, which is metabolized to TPA, involves urinary acidosis, altered electrolyte elimination and hypercalciuria, urinary supersaturation with calcium terephthalate or calcium hydrogen terephthalate, and crystallization into bladder calculi. Weanling rats were more sensitive to calculus formation than dams. Calculi-induced irritation led to bladder hyperplasia and tumors in rats fed 1000 mg/kg-day TPA. The lack of effects at 142 mg/kg-day supports a threshold for urine saturation with calcium terephthalate, a key event for calculus formation. Chronic dietary DMT exposure in rodents caused kidney inflammation, but not calculi. Chronic dietary DEHT exposure caused general toxicity unrelated to calculi, although urine pH was reduced suggesting the TPA metabolite was biologically-active, but of insufficient concentration to induce calculi. Respective oral reference doses of 0.5, 0.5, and 0.2 mg/kg-day and total allowable drinking water concentrations of 3, 3, and 1 mg/L were derived for TPA, DMT, and DEHT. An oral RfD of 0.2 mg/kg-day for the terephthalate category chemicals corresponded to a drinking water TAC of 1 mg/L.

An EGFR-ERK-SOX9 signaling cascade links urothelial development and regeneration to cancer

Like many carcinomas, urothelial carcinoma (UroCa) is associated with chronic injury. A better understanding of this association could inform improved strategies for preventing and treating this disease. We investigated the expression, regulation, and function of the transcriptional regulator SRY-related high-mobility group box 9 (Sox9) in urothelial development, injury repair, and cancer. In mouse bladders, Sox9 levels were high during periods of prenatal urothelial development and diminished with maturation after birth. In adult urothelial cells, Sox9 was quiescent but was rapidly induced by a variety of injuries, including exposure to the carcinogen cyclophosphamide, culture with hydrogen peroxide, and osmotic stress. Activation of extracellular signal-regulated kinases 1/2 (ERK1/2) was required for Sox9 induction in urothelial injury and resulted from activation of the epidermal growth factor receptor (Egfr) by several Egfr ligands that were dramatically induced by injury. In UroCa cell lines, SOX9 expression was constitutively upregulated and could be suppressed by EGFR or ERK1/2 blockade. Gene knockdown showed a role for SOX9 in cell migration and invasion. Accordingly, SOX9 protein levels were preferentially induced in invasive human UroCa tissue samples (n = 84) compared with noninvasive cancers (n = 56) or benign adjacent urothelium (n = 49). These results identify a novel, potentially oncogenic signaling axis linking urothelial injury to UroCa. Inhibiting this axis is feasible through a variety of pharmacologic approaches and may have clinical utility.

Suppressive effects of acid-forming diet against the tumorigenic potential of pioglitazone hydrochloride in the urinary bladder of male rats

Pioglitazone hydrochloride (PIO), a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, was administered orally for 85 weeks at 16 mg/kg/day to male rats fed either a diet containing 1.5% ammonium chloride (acid-forming diet) or a control diet to investigate the effects of urinary acidification induced by the acid-forming diet on the tumorigenic potential of PIO in the urinary bladder. The surviving animals at the end of the administration period were followed to the end of the 2-year study period without changes in the diet and were subjected to terminal necropsy on Week 104. The number of urinary microcrystals, evaluated by manual counting with light microscopy and by an objective method with a laser diffraction particle size analyzer, was increased by PIO on Weeks 12 and 25 and the increases were markedly suppressed by urinary acidification. Urinary citrate was decreased by PIO throughout the study period, but no changes were seen in urinary oxalate at any timepoint. The incidences of PIO-treated males bearing at least one of the advanced proliferative changes consisting of papillary hyperplasia, nodular hyperplasia, papilloma or carcinoma were significantly decreased from 11 of 82 males fed the control diet to 2 of 80 males fed the acid-forming diet. The acid-forming diet did not show any effects on the toxicokinetic parameters of PIO and its metabolites. Microcrystalluria appears to be involved in the development of the advanced stage proliferative lesions in bladder tumorigenesis induced by PIO in male rats.

Role of bacteria in oncogenesis

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

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.

Guidance for the classification of carcinogens under the Globally Harmonised System of Classification and Labelling of Chemicals (GHS)

The United Nations Conference on Environment and Development (UNCED) has developed criteria for a globally harmonised system of classification and labelling of chemicals (GHS). With regard to carcinogenicity, GHS distinguishes between Category 1 ('known or presumed human carcinogens') and Category 2 ('suspected human carcinogens'). Category 1 carcinogens are divided into Category 1A ('known to have carcinogenic potential for humans'), based largely on human evidence, and 1B ('presumed to have carcinogenic potential for humans'), based largely on experimental animal data. Concerns have been raised that the criteria for applying these carcinogenicity classifications are not sufficiently well defined and potentially allow different conclusions to be drawn. The current document describes an attempt to reduce the potential for diverse conclusions resulting from the GHS classification system through the application of a series of questions during the evaluation of data from experiments with rodents; epidemiological data, which could lead to Category 1A, have not been considered. Answers to each question can lead either to a classification decision or to the next question, but this process should only be implemented in an environment of informed scientific opinion. The scheme is illustrated with five case studies. These questions are: (1) Has a relevant form of the substance been tested? (2) Is the study design relevant to human exposure? (3) Is there a substance-related response? (4) Is the target tissue exposure relevant to humans? (5) Can a mode of action be established? (6) Is the mode of action relevant to humans? (7) What is the potency?

Derivation of a melamine oral reference dose (RfD) and drinking-water total allowable concentration

Due to its high nitrogen content, melamine has been used to adulterate food to increase apparent protein content. In 2008, thousands of Chinese infants consumed reconstituted formula derived from melamine-adulterated milk. Urinary-tract stones (comprised of melamine and uric acid) accumulated in some victims and lead to acute renal failure or death. Premature infants and children (<2 yr) have an increased susceptibility to ingested melamine. Due to incomplete reporting, the human data were inadequate to identify a no-observed-adverse-effect level (NOAEL) for melamine-induced pediatric urolithiasis. Urolithiasis, urinary bladder cystitis, and ulcerations were observed in F344 rats after subchronic or chronic ingestion of melamine at > or =72 mg/kg-d. Bladder epithelial damage was followed by epithelial hyperplasia that progressed to bladder papillomas and carcinomas in male but not female F344 rats or male or female B6C3F1 mice. Short-term assays suggest, at best, weak genotoxic activity, and kinetic data show that melamine is not metabolized. Since reliable exposure information was lacking from the clinical reports, an oral reference dose (RfD) based on urolithiasis in male rats after 13 wk of continuous melamine ingestion was calculated as a 10% benchmark dose (38 mg/kg-d). Incorporation of 10-fold interspecies and intraspecies (for the increased susceptibility of infants) uncertainty factors and a threefold database uncertainty factor (for the lack of immunological, neurological and reproduction toxicity data) yields an oral RfD of 0.13 mg/kg-d. Assuming the 70-kg adult consumes 2 L of drinking water daily, a total allowable concentration of 0.9 mg/L (900 microg/L) was calculated for melamine in drinking water.

An enhanced 13-week bioassay: an alternative to the 2-year bioassay to screen for human carcinogenesis

The 2-year rodent bioassay has become the standard carcinogenicity screen for chemicals, despite concerns of costs, time, and excessive doses. More importantly, there are increasing concerns regarding its relevance to human carcinogenic risk, especially for non-DNA reactive chemicals. Cancer risk can be increased either by direct damage to DNA (DNA reactivity) or by increased cell proliferation. Utilizing the scientific basis for mode of action analysis in the framework that has been developed for extrapolating to human relevance, a short-term screen is proposed as a replacement for the 2-year bioassay. Chemicals are evaluated for DNA reactivity, immunosuppression, and estrogenic activity, known mechanisms of human carcinogenesis, by in vitro and/or in vivo tests. The chemical can then be evaluated for toxicity and/or increased cell proliferation in target tissues. This relies primarily on evaluation of organ weights and histopathology, and also utilizes data from blood and urine chemistries and DNA-labeling indices. Significant concern is raised regarding the relevance of evaluation of tissues that are present in rats or mice but not humans, and the relevance of proliferative responses in rodent endocrine tissues. In developing alternative procedures to evaluate chemicals for possible carcinogenic activity in humans, it is important not to rely on the 2-year rodent bioassay for validation of the new procedure. It is time to discontinue the performance of the 2-year rodent bioassay.

Urinary tract infections and reduced risk of bladder cancer in Los Angeles

We investigated the association between urinary tract infections (UTIs) and transitional cell carcinoma of the bladder in a population-based case–control study in Los Angeles covering 1586 cases and age-, gender-, and race-matched neighbourhood controls. A history of bladder infection was associated with a reduced risk of bladder cancer among women (odds ratio (OR), 0.66; 95% confidence interval (CI), 0.46–0.96). No effect was found in men, perhaps due to power limitations. A greater reduction in bladder cancer risk was observed among women with multiple infections (OR, 0.37; 95% CI, 0.18–0.78). Exclusion of subjects with a history of diabetes, kidney or bladder stones did not change the inverse association. A history of kidney infections was not associated with bladder cancer risk, but there was a weak association between a history of other UTIs and slightly increased risk among men. Our results suggest that a history of bladder infection is associated with a reduced risk of bladder cancer among women. Cytotoxicity from antibiotics commonly used to treat bladder infections is proposed as one possible explanation.

Multipathogenetic origin of a pelvic mass

A 69-yr-old woman presented with a bulky hypogastric mass and abdominal pain. Computed tomography scan showed a mass anterosuperior and contiguous to the bladder wall, with a hypodense content, a voluminous bladder stone, and bilateral hydroureteronephrosis. Intraoperatively, the supravesical mass had the appearance of an infected urachal cyst. An unsuspected high-grade noninvasive papillary transitional cell carcinoma (TCC) of the bladder thoroughly surrounding the bladder stone became evident during the cystolithotomy. Postoperative videourodynamic study showed a normal voiding pattern with bilateral grade 4 vesicoureteral reflux. Early cystectomy was performed for uncontrolled recurrent bladder cancer, and the final pathology indicated pT1G3N0 TCC.

Possible Contribution of Indomethacin to the Carcinogenicity of Nongenotoxic Bladder Carcinogens That Cause Bladder Calculi

Nongenotoxic bladder carcinogens that form bladder calculi have been concluded to be of low carcinogenic risk to humans because bladder stones would be expelled or surgically removed before they had a chance to exert their carcinogenic effect. It is the aim of this report to examine the possible contribution of indomethacin to the carcinogenic risk posed by nongenotoxic bladder carcinogens that cause bladder stones. Indomethacin may act as a tumor promoter in the bladder by interfering with the synthesis of prostaglandins. Prostaglandins have a cytoprotective function in the gastric mucosa and possibly also in the urinary bladder. Diminished cytoprotection may be implicated in bladder carcinogenesis as beta-naphthylamine, a human bladder carcinogen, also inhibits prostaglandin synthesis in vitro. The presence of other tumor promoters in the bladder may further ensure that tumors would be formed even if bladder stones were expelled. People who are exposed to nongenotoxic bladder carcinogens that are present in the environment and that form bladder stones, therefore, may be at an increased risk for developing bladder cancer if they are also exposed to tumor promoters, such as indomethacin.

A Framework for Human Relevance Analysis of Information on Carcinogenic Modes of Action

The human relevance framework (HRF) outlines a four-part process, beginning with data on the mode of action (MOA) in laboratory animals, for evaluating the human relevance of animal tumors. Drawing on U.S. EPA and IPCS proposals for animal MOA analysis, the HRF expands those analyses to include a systematic evaluation of comparability, or lack of comparability, between the postulated animal MOA and related information from human data sources. The HRF evolved through a series of case studies representing several different MOAs. HRF analyses produced divergent outcomes, some leading to complete risk assessment and others discontinuing the process, according to the data available from animal and human sources. Two case examples call for complete risk assessments. One is the default: When data are insufficient to confidently postulate a MOA for test animals, the animal tumor data are presumed to be relevant for risk assessment and a complete risk assessment is necessary. The other is the product of a data-based finding that the animal MOA is relevant to humans. For the specific MOA and endpoint combinations studied for this article, full risk assessments are necessary for potentially relevant MOAs involving cytotoxicity and cell proliferation in animals and humans (Case Study 6, chloroform) and formation of urinary-tract calculi (Case Study 7, melamine). In other circumstances, when data-based findings for the chemical and endpoint combination studied indicate that the tumor-related animal MOA is unlikely to have a human counterpart, there is little reason to continue the risk assessment for that combination. Similarly, when qualitative considerations identify MOAs specific to the test species or quantitative considerations indicate that the animal MOA is unlikely to occur in humans, such hazard findings are generally conclusive and further risk assessment is not necessary for the endpoint-MOA combination under study. Case examples include a tumor-related protein specific to test animals (Case Study 3, d-limonene), the tumor consequences of hormone suppression typical of laboratory animals but not humans (Case Study 4, atrazine), and chemical-related enhanced hormone clearance rates in animals relative to humans (Case Study 5, phenobarbital). The human relevance analysis is highly specific for the chemical-MOA-tissue-endpoint combination under analysis in any particular case: different tissues, different endpoints, or alternative MOAs for a given chemical may result in different human relevance findings. By providing a systematic approach to using MOA data, the HRF offers a new tool for the scientific community's overall effort to enhance the predictive power, reliability and transparency of cancer risk assessment.

Profiling of genetic variations in inflammation pathway genes in relation to bladder cancer predisposition

PURPOSE

Compelling evidence has indicated that inflammation plays an important role in cancer development. We sought to test the hypothesis that common sequence variants in the inflammation pathway modulate bladder cancer risk.

EXPERIMENTAL DESIGN

We genotyped 59 potentially functional single nucleotide polymorphisms from 35 candidate inflammation genes in a case-control study including 635 Caucasian bladder cancer patients and 635 matched controls.

RESULTS

The most significant finding was in the 3'-untranslated region of PTGS2 (exon10+837T>C, rs5275), which was associated with a significantly reduced risk (odds ratio, 0.68; 95% confidence interval, 0.54-0.87; P=0.002) and remained significant after multiple comparison adjustment. Consistently, the most common PTGS2 haplotype containing the common allele of exon10+837T>C was associated with a significantly increased risk (odds ratio, 1.27; 95% confidence interval, 1.06-1.52; P=0.008). In contrast, the haplotypes containing at least one variant allele of exon10+837T>C were all associated with a decreased risk. In a combined analysis to assess the cumulative effects of inflammation single nucleotide polymorphisms on bladder cancer risk, we found that in the anti-inflammation pathway, but not in the proinflammation pathway, when compared with individuals with a few adverse alleles, individuals with more adverse alleles had a significantly increased risk in a dose-dependent manner (P(trend)=0.012). To further elucidate the functional mechanism of these associations, we redefined the adverse alleles based on literature-reported functional results and found that individuals with a higher number of inflammation-enhancing alleles in the anti-inflammation pathway exhibited a greater bladder cancer risk.

CONCLUSIONS

Our results strongly suggest that common variants in inflammation genes affect bladder cancer susceptibility individually and jointly.

Rodent Carcinogenicity Profile of the Antidiabetic Dual PPAR α and γ Agonist Muraglitazar

The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated receptor alpha/gamma agonist, was evaluated in 2-year studies in mice (1, 5, 20, and 40 mg/kg) and rats (1, 5, 30, and 50 mg/kg). Benign gallbladder adenomas occurred at low incidences in male mice at 20 and 40 mg/kg (area under the curve [AUC] exposures > or = 62 times human exposure at 5 mg/day) and were considered drug related due to an increased incidence of gallbladder mucosal hyperplasia at these doses. There was a dose-related increased incidence of transitional cell papilloma and carcinoma of the urinary bladder in male rats at 5, 30, and 50 mg/kg (AUC exposures > or = 8 times human exposure at 5 mg/day). At 30 and 50 mg/kg, the urinary bladder tumors were accompanied by evidence of increased urine solids. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Incidences of subcutaneous liposarcoma in male rats and subcutaneous lipoma in female rats were increased at 50 mg/kg (AUC exposures > or = 48 times human exposure at 5 mg/day) and attributed, in part, to persistent pharmacologic stimulation of preadipocytes. Toxicologically relevant nonneoplastic changes in target tissues included thinning of cortical bone in mice and hyperplastic and metaplastic adipocyte changes in mice and rats. Considering that muraglitazar is nongenotoxic, the observed tumorigenic effects in mice and rats have no established clinical relevance since they occurred at either clinically nonrelevant exposures (gallbladder and adipose tumors) or by a species-specific mechanism (urinary bladder tumors).

Urothelial carcinogenesis in the urinary bladder of male rats treated with muraglitazar, a PPAR alpha/gamma agonist: Evidence for urolithiasis as the inciting event in the mode of action

Muraglitazar, a PPARalpha/gamma agonist, dose-dependently increased urinary bladder tumors in male Harlan Sprague-Dawley (HSD) rats administered 5, 30, or 50 mg/kg/day for up to 2 years. To determine the mode of tumor development, male HSD rats were treated daily for up to 21 months at doses of 0, 1, or 50 mg/kg while being fed either a normal or 1% NH4Cl-acidified diet. Muraglitazar-associated, time-dependent changes in urine composition, urothelial mitogenesis and apoptosis, and urothelial morphology were assessed. In control and treated rats fed a normal diet, urine pH was generally > or = 6.5, which facilitates formation of calcium-and magnesium-containing solids, particularly in the presence of other prolithogenic changes in rat urine. Urinary citrate, an inhibitor of lithogenesis, and soluble calcium concentrations were dose dependently decreased in association with increased calcium phosphate precipitate, crystals and/or microcalculi; magnesium ammonium phosphate crystals and aggregates; and calcium oxalate-containing thin, rod-like crystals. Morphologically, sustained urothelial cytotoxicity and proliferation with a ventral bladder predilection were noted in treated rats by month 1 and urinary carcinomas with a similar distribution occurred by month 9. Urothelial apoptotic rates were unaffected by muraglitazar treatment or diet. In muraglitazar-treated rats fed an acidified diet, urine pH was invariably < 6.5, which inhibited formation of calcium-and magnesium-containing solids. Moreover, dietary acidification prevented the urothelial cytotoxic, proliferative, and tumorigenic responses. Collectively, these data support an indirect pharmacologic mode of urinary bladder tumor development involving alterations in urine composition that predispose to urolithiasis and associated decreases in urine-soluble calcium concentrations.

Bladder squamous metaplasia of the urothelium - introductory report

Seven female patients hospitalized in the Surgery Ward of Warsaw's Hospital for Children are described. Nonspecific abdominal pains, recurrent urinary tract infections, and voiding disorders (difficulty in voiding commencement) were the primary causes of hospitalization. Urodynamics and cystoscopy with a histopathology section of the urothelium achieved the diagnosis of nonkeratizing squamous cell metaplasia of the urothelium. The topic is not new, although the diagnosis is particularly rare in the pediatric patient. Until now, the existing world literature has described only a few cases of this kind of metaplasia in children. These findings may be helpful in differential diagnosis of urinary bladder disease. It is postulated that nonkeratizing squamous cell metaplasia of the urothelium, in the future, may lead to malignant changes in the urothelium. Therefore, the therapeutic process merits close monitoring.

Bladder epithelial cell proliferation of rats induced by terephthalic acid-calculi

OBJECTIVE

Urinary bladder hyperplasia associated with terephthalic acid (TPA) treatment was examined with concomitant use of sodium bicarbonate (NaHCO3) or hydrochlorothiazide to allow assessment of the relationship among bladder stones, epithelial hyperplasia, and corresponding cell cycle checkpoint gene expression in Sprague-Dawley (SD) rat.

METHODS

A total of 112 weanling male SD rats that divided between six groups were given basal diet (control), diets containing 5% TPA or in combination with either 4% sodium NaHCO3 or 0.02% hydrochlorothiazide. After 90-day feeding, bladder samples were collected for histopathological diagnoses, and immunohistochemical method was used to characterize the expression of p16Ink4a cyclin D1, CDK4, EGFr and cyclin E in relation to that of proliferating cell nuclear antigen (PCNA).

RESULTS

In TPA treatment groups, bladder stone incidence was 40% (21/52) with 14 cases of proliferative bladder. In control and other groups, neither stone nor epithelial cell proliferation was diagnosed. PCNA-positive focal hyperplasic lesions involved all epithelial layers. Overexpressions of cyclin D1, CDK4, EGFr are found in the corresponding lesion. p16Ink4a nuclear staining reduced in proliferative bladders especially with a great quantity of stone. In addition, no positive expression was detected on cyclin E.

CONCLUSION

The present study provides a strong evidence of a link between induction of bladder hyperplasia, deregulation of the p16Ink4a-cyclin D1/CDK4 pathway, and abnormal EGFr mediated signal transduction pathway.

Neoplastic and preneoplastic lesions induced by melamine in rat urothelium are modulated by dietary polyunsaturated fatty acids

The modulatory effects of polyunsaturated fatty acids (PUFA) on urinary tract tumorigenesis of 275 Wistar rats were evaluated by treating animals with the tumorigenic agent melamine. Rats were fed with formulae containing 6% of 4 varieties of fats: fish oil enriched in n-3 PUFA (FO), corn oil enriched in n-6 (CO), olein containing mainly n-9 oleic acid (O), and 98% stearic acid (SA), the latter two being essential (EFA)-deficient inducers. Two commercially fed control groups with (CM) and without (C) melamine were used. Animals were autopsied at 22-25 and at 36-40 weeks. Hepatic fatty acids showed that O and SA groups were EFA-deficient. Simple well differentiated hyperplasias were significantly higher in the FO lot, whereas dysplasia was increased in the CO, O and SA lots. Most of the animals fed for 36-40 weeks with the three latter formulae developed the more severe lesions. Increased urothelial proliferation was more frequent in EFA-deficient rats. The apoptosis/mitosis ratio was higher in O, SA and CO fed animals with respect to FO and chow ones. Results show that dietary PUFA modulate differentially both normal and pre-neoplastic urothelial proliferation induced by melamine. FO, rich in n-3 fatty acids, showed a strong protective effect.

Fluid intake and risk of bladder and other cancers

There are appreciable differences in total fluid intake at the individual and population level, and substantial difficulties in obtaining valid measures of fluid intake. Epidemiological studies have examined the association between fluid intake and different types of cancer. For bladder cancer, fluid consumption has been associated with a moderate increase of risk in some studies, including a multicentric case-control study from the United States, based on about 3000 cases, with a decrease in others, including the Health Professional Follow-up study, or with no material association. The evidence, therefore, is far from consistent. Sources and components of fluids were also different across different types studies. From a biological point of view, a decreased fluid intake could result in a greater concentration of carcinogens in the urine or in a prolonged time of contact with the bladder mucosa because of less frequent micturition. Carcinogenic or anticarcinogenic components of various beverages excreted in the urine may also play a role in the process. It has been suggested that fluid consumption has a favorable effect on colorectal cancer risk. Fluid intake may reduce colon cancer risk by decreasing bowel transit time and reducing mucosal contact with carcinogens. Low fluid intake may also compromise cellular concentration, affect enzyme activity in metabolic regulation, and inhibit carcinogen removal. However, epidemiological data are inadequate for evaluation. Data are sparse and inconsistent for other neoplasms, including breast cancer. The fluid constituent of foods, confounding, interactions and possible influences of specific types of beverages should be investigated further. In conclusion therefore the association between total fluid intake and cancer risk remains still open to debate.

The Potential Contributions of Chronic Inflammation to Lung Carcinogenesis

A number of lines of evidence suggests that chronic inflammation contributes to the process of carcinogenesis. In this article, this theme is explored with particular emphasis on the involvement of inflammation in the development of lung cancer. A number of molecular pathways activated in chronic inflammation may contribute to lung carcinogenesis. The challenge is to conceptualize a cohesive picture of this complex biology that allows for effective pharmaceutical intervention. Initial therapeutic efforts involve strategies to block single pathways, such as with cyclooxygenase (COX) activity. However, the more that is learned about the consequences of COX activity, the more evident are the relationships of this enzyme to other classes of regulatory molecules such as the potent nuclear factor-kB. In light of this emerging picture, more global intervention strategies, such as with drug combinations, may be essential for success. Further basic study is essential to sort out possible molecular relationships and to permit elucidation of the most critical regulatory circuits. Given the complexity of these molecular interactions, well-designed clinical trials that specifically evaluate the precise effects of particular antiinflammatory drugs on lung carcinogenesis will also be critical to sort out the complexity and to validate successful approaches to arresting lung carcinogenesis.

Comparative pathology of proliferative lesions of the urinary bladder

Bladder neoplasia in humans consists of 2 diseases, a low-grade papillary tumor that does not invade or metastasize, and a high-grade lesion that usually invades and metastasizes. Bladder carcinogenesis in rats is most like the low-grade, papillary tumor, although it eventually does progress and invade. In the mouse, models are available that mimic each of these disease processes. Preneoplastic lesions in humans and rodents include various types of hyperplasia, proliferative cystitis, and dysplasia. These preneoplastic and neoplastic lesions arise throughout the urothelium, from the renal pelvis to the urethra, although most commonly in the bladder. Rarely, benign and malignant mesenchymal lesions occur in rats and mice, with a unique submucosal mesenchymal lesion present in some strains of mice. In addition, eosinophilic and clear inclusions in the superficial layer of urothelium in mice, which do not appear to be associated with toxicity or carcinogenesis, have been reported. An approach to evaluation of carcinogenic mechanisms involved in the urothelium is presented. It focuses on distinguishing between DNA reactive carcinogens vs those that act by increasing cell proliferation. Although rodent models do not precisely mimic the human disease, they have provided useful models for furthering our understanding of the carcinogenic process in the urothelium as it pertains to human diseases.

Urinary tract calculi and thresholds in carcinogenesis

Numerous chemicals administered to rodents at relatively high doses produce urinary tract calculi, resulting in erosions or ulcerations of the urothelium, consequent regenerative hyperplasia, and ultimately tumors. This is a high-dose (threshold) phenomenon, which appears to occur more readily in rodents than in primates, including humans. Several anatomic and urinary physiologic differences between rodents and humans affect the quantitative extrapolation from results in rodent bioassays to human risk assessment. For most chemicals producing tumors by this mode of action, human exposures are significantly lower than would be expected to be required for production of calculi, and therefore pose no carcinogenic hazard to humans.

Lack of enhancing effect of two Kampo medicines, Sho-saiko-to (TJ-9) and Sairei-to (TJ-114), on rat urinary bladder carcinogenesis initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine

The modifying potential of two Kampo medicines (Japanese traditional herbal medicines), Sho-saiko-to (TJ-9) and Sairei-to (TJ-114), on urinary bladder carcinogenesis in male F344 rats initiated with N-butyl-N-(4-hydroxybutyl)- nitrosamine (BBN) was evaluated. Groups of 20 animals were given 0.05% BBN in their drinking water for 4 weeks and then 0.7 or 2.8% TJ-9, 0.9 or 3.6% TJ-114, or 3.0% sodium bicarbonate (NaHCO(3)) as a positive control substance in their diet for 32 weeks. All rats were killed after 36 weeks and examined histopathologically. No adverse effects of the test compounds were found in terms of survival, clinical sign, and body weight. Administration of 0.7 and 2.8% TJ-9 and 0.9 and 3.6% TJ-114 in the diet did not affect the incidences or extent of PN hyperplasia in the BBN-treated rats. Incidences and multiplicities of papillomas were also not affected in rats fed 0.7 or 2.8% TJ-9 and 0.9% TJ-114, while they were significantly decreased in animals given 3.6% TJ-114 in the diet. The results thus demonstrated that neither of the test chemicals exerted any promotional activity on urinary bladder carcinogenesis, in clear contrast to NaHCO(3). In addition, bladder carcinogenesis was reduced by 3.6% TJ-114 in the diet, under the present experimental conditions.

Inflammation, carcinogenesis and cancer

To fulfill their role in host-defense, granulocytes secrete chemically reactive oxidants, radicals, and electrophilic mediators. While this is an effective way to eradicate pathogenic microbes or parasites, it inevitably exposes epithelium and connective tissue to certain endogenous genotoxic agents. In ordinary circumstances, cells have adequate mechanisms to reduce the genotoxic burden imposed by these agents to a negligible level. However, inflammation persisting for a decade eventually elevates the risk of cancer sufficiently that it is discernible in case control epidemiological studies. Advances in our understanding of tumor suppressors and inflammatory mediators offer an opportunity to assess the molecular and cellular models used to guide laboratory investigations of this phenomenon. Disappointing results from recent clinical trials with anti-oxidant interventions raise questions about the risks from specific endogenous agents such as hydrogen peroxide and oxy radicals. Simultaneously, the results from the anti-oxidant trials draw attention to an alternate hypothesis, favoring epigenetic inactivation of key tumor suppressors, such as p53, and the consequent liability this places on genomic integrity.

Effect of sulfosulfuron on the urine and urothelium of male rats

Sulfosulfuron, developed as a herbicide, caused increased microcrystalluria and the formation of urinary tract calculi when fed to male and female rats in a chronic 2-year study at doses of 5,000 ppm and 20,000 ppm. Hyperplasia was also seen in urinary bladders at 5,000 ppm and 20,000 ppm, almost exclusively in the presence of observable calculi/microcalculi. Urinary bladder tumors were found in 2 females in the 5000 ppm group, both in the presence of calculi. No increased microcrystalluria, calculi, or tumors were found at doses of 500 ppm and lower. In the current study, 5 groups of male Sprague-Dawley rats were fed sulfosulfuron at doses of 50, 500, 5,000, and 20,000 ppm for 10 weeks. Ten animals were co-administered 5,000 ppm sulfosulfuron with 12,300 ppm NH4Cl to determine if inhibition of the formation of calculi would prevent any urothelial effects of treatment with sulfosulfuron. Ten animals in the control group and in the high-dose sulfosulfuron group were fed only basal diet for an additional 10 weeks to determine if the effects of sulfosulfuron on the bladder epithelium were reversible. There was an increased incidence of microcrystalluria observed at 5,000 and 20,000 ppm. There was no increase in microcrystalluria observed in the urine of rats co-administered sulfosulfuron and NH4Cl. Urinary bladder calculi were found in the bladder of 1 animal fed 20,000 ppm. Examination by light microscopy showed diffuse papillary/nodular hyperplasia of the bladder epithelium in this animal. No increased microcrystalluria was observed after withdrawal of the chemical from the diet and the bladder epithelium was normal by light microscopy. The hyperplastic effects associated with the feeding of high doses of sulfosulfuron occur only with the appearance of urinary tract calculi. Based on these results and anatomical differences between rats and humans, it may be concluded that the hyperplastic and carcinogenic effects of sulfosulfuron in rats are high-dose, threshold phenomena that are not likely to occur in humans under environmentally relevant exposures.

Cyclooxygenase-2 and carcinogenesis

Numerous investigations have shown that COX-2 is a participant in the pathway of colon carcinogenesis, especially when mutation of the APC tumor suppressor is the initiating event. Moreover, it seems that the amount of COX-2 is important, since there is a correlation between its level of expression and the size of the tumors and their propensity to invade underlying tissue [40]. Inhibiting COX-2 at an early stage blocks the development of malignant tumors, causes pre-malignant tumors to regress and may improve the outcome once the cancer is completely established. This set of findings seems to link very strongly with the traditional observation that chronic inflammation is a precursor to a variety of types of cancer. By this formulation, inflammatory stimuli increase COX-2 and the downstream events that it induces promote tumor formation. All of these finding suggest that existing NSAIDs will be useful for the prophylaxis of colon cancer and polyps and we eagerly await clinical investigations that will generate guidelines that suggest those individuals that are the most appropriate recipients for such therapy. Although this field has progressed rapidly in the last few years, many important questions remain.

Cancer cell necrosis by autoschizis: synergism of antitumor activity of vitamin C: vitamin K3 on human bladder carcinoma T24 cells

Scanning and transmission electron microscopy and fluorescence light microscopy were employed to characterize the cytotoxic effects of vitamin C (VitC), vitamin K3 (VitK3) or a VitC:VK3 combination on a human bladder carcinoma cell line (T24) following 1-h and 2-h vitamin treatment. T24 cells exposed to VitC alone exhibited membranous damage (blebs and endoplasmic extrusions, elongated microvilli). VitK3-treated cells displayed greater membrane damage and enucleation than those treated with VitC as well as cytoplasmic defects characteristic of cytoskeletal damage. VitC:VitK3-treated cells showed exaggerated membrane damage and an enucleation process in which the perikarya separate from the main cytoplasmic cell body by self-excision. Self-excisions continued for perikarya which contained an intact nucleus surrounded by damaged organelles. After further excisions of cytoplasm, the nuclei exhibited nucleolar segregation and chromatin decondensation followed by nuclear karryorhexis and karyolysis. This process of cell death induced by oxidative stress was named autoschizis because it showed both apoptotic and necrotic morphologic characteristics.

Smoking and urological disease

It is important to realise that virtually every part of the body, including the urological system, is adversely affected by smoking. Smoking is the most important known preventable cause of urinary bladder cancer and is also associated with a risk of prostatic and renal cancer. The exact mechanism by which smoking increases the incidence of urological malignancy is not known. One possibility is that chemicals in cigarette smoke inhibit the synthesis of cytoprotective eicosanoids. Deficient local protection, against the hostile environment caused by the presence of urine, could then encourage the process of carcinogenesis. Smoking is a powerful predictor of erectile dysfunction; cessation may restore normal function. Cigarette smoke also exerts adverse effects on sperm motility and count. Although there is no convincing evidence of reduced fertility in male smokers, it is advisable for men to quit smoking should they have marginal semen quality and wish to start a family. Smoking causes substantial urological pathology; these facts can be used to convince patients with urological problems to quit smoking.

Urinary bladder carcinogenesis

Urinary bladder carcinogenesis in rodents bears numerous similarities to the diseases in humans. In rats, the process progresses through the morphologic stages of simple hyperplasia, papillary and nodular hyperplasia, papilloma, noninvasive, and invasive carcinoma. In mice, the pathogenesis can be similar or can follow a sequence of marked dysplasia with or without hyperplasia, leading to carcinoma in situ and ultimately to high-grade invasive carcinoma. Although the papillary and nonpapillary diseases appear to be related in rodents and in humans, they are distinct morphologically, biologically, and molecularly. Numerous classes of genotoxic chemicals have been identified as bladder carcinogens in rodents, and some of these have also been identified as carcinogenic in humans, most notably, aromatic amines, nitrosamines, and cyclophosphamide. In contrast, nongenotoxic chemicals appear to be highly specific with respect to species, strain, diet, agent, dose, and mechanism. For some, it is unclear whether the results at high doses in rodents can be extrapolated to low doses or to humans, e.g., chemicals that cause bladder cancer only at high doses related to the formation of calculi. Numerous observations in rodents can assist in identifying possible mechanisms involved for these nongenotoxic chemicals and therefore can be important for a rational evaluation of human risk.

Epidemiology and etiology of bladder cancer

The incidence of bladder cancer continues to increase, with an estimated 53,000 new cases diagnosed in the United States in 1996-90% of which are transitional cell carcinomas. The male-to-female ratio is 3:1. A number of etiological factors are associated with the development of bladder cancer, but in industrialized countries, cigarette smoking is the most important. Specific chemicals have also been identified as causing bladder cancer, as have a number of occupational exposures to less well-defined specific agents. Treatment with cytostatic drugs, especially cyclophosphamide, is associated with increased risk of bladder cancer, as is treatment with radiotherapy for uterine cancer. In developing countries, especially in the Middle East and parts of Africa, infections with members of the genus Schistosoma are responsible for a high incidence of bladder cancer-75% of which are squamous cell carcinomas. Arsenic has been indicated as a bladder carcinogen in Argentina, Chile, and Taiwan. The reason for the high incidence of urinary tract cancer in individuals suffering from Balkan nephropathy has yet to be determined. A careful history of patients with bladder cancer is an important and useful process in helping to identify causal factor and, in more than one-half the cases, a known relationship is found. Bladder cancer is a potentially preventable disease, with a significant morbidity and mortality in many parts of the world.

Effects of diet on urinary bladder carcinogenesis and cancer prevention

Urine plays a major role in bladder carcinogenesis, acting as a transport mechanism for carcinogens, containing several growth factors stimulating cell proliferation, and indirectly affecting chemicals by alterations in concentrations of normal urinary components such as electrolytes, water and proteins. These latter effects are greatly modified by diet composition and consumption and also by water consumption. Several examples of these effects are presented.

Role of cell proliferation in regenerative and neoplastic disease

DNA replication does not have 100% fidelity. Consequently, a chemical can increase the risk of cancer either by directly damaging DNA (genotoxic) or by increasing the number of cell replications, or both. Increased cell proliferation can be produced by increasing cell births (by direct mitogenesis or regeneration following toxicity), or decreasing cell deaths (by inhibiting apoptosis or differentiation). Cell proliferation can affect the dose-response curve for genotoxic carcinogens and is the basis for carcinogenicity by nongenotoxic agents. Bladder carcinogens will be used to illustrate these mechanisms, and their implications with respect to human risk assessment will be presented.

Epithelial tumours of the lower urinary tract in humans and rodents

Bladder neoplasms that are morphologically similar to those occurring in the human bladder can be induced in rats and mice. Thus, these animal models can provide useful information in elucidating the histogenesis of the human bladder cancer. It is unknown whether human and rodent bladder cancers share similar molecular mechanism(s). There are species-specific differences in the type of neoplastic lesions. In rats, irrespective of the carcinogen used, the lesions tend to be polypoid exophytic masses and invasion is a late event, occurring only after a large dose of carcinogen and after an extended period of observation. On the other hand, mice tend to develop nodular invasive carcinomas readily preceded by the development of CIS. In both species, the neoplasms tend to show squamous differentiation, and metastatic spread is rare. Nevertheless, both species provide a useful model for the assessment of human risk of test chemicals because the principal neoplastic lesions that develop in response to test carcinogens are transitional cell neoplasms. Further study of cases of chemically, induced bladder cancer in rodents is essential to determine the applicability of the mode of action to humans.

Rodent bladder tumors do not always predict for humans

Dr. David Clayson, 20 years ago, suggested that chemicals which lead to the formation of calculi in rodents might pose an artifact with respect to extrapolation to potential carcinogenic risk to humans. We reviewed what has been learned about the role of calculi in urinary bladder carcinogenesis in the ensuing 20 years, along with several examples. Formation of microcrystalluria and amorphous precipitate also poses problems in interpretation and examples are described. The chemicals producing these solid urinary materials are non-genotoxic, with marked increase in cell proliferation being the mode of action by which they are able to produce cancer in long-term rodent bioassays.