Urothelial umbrella cells of human ureter are heterogeneous with respect to their uroplakin composition: different degrees of urothelial maturity in ureter and bladder?

Upper Tract Urinary Carcinoma: A Unique Immuno-Molecular Entity and a Clinical Challenge in the Current Therapeutic Scenario

Urothelial carcinoma (UC) is the most frequent malignancy of the urinary tract, which consists of bladder cancer (BC) for 90%, while 5% to 10%, of urinary tract UC (UTUC). BC and UTUC are characterized by distinct phenotypical and genotypical features as well as specific gene- and protein- expression profiles, which result in a diverse natural history of the tumor. With respect to BC, UTUC tends to be diagnosed in a later stage and displays poorer clinical outcome. In the present review, we seek to highlight the individuality of UTUC from a biological, immunological, genetic-molecular, and clinical standpoint, also reporting the most recent evidence on UTUC treatment. In this regard, while the role of surgery in nonmetastatic UTUC is undebated, solid data on adjuvant or neoadjuvant chemotherapy are still an unmet need, not permitting a definite paradigm shift in the standard treatment. In advanced setting, evidence is mainly based on BC literature and retrospective studies and confirms platinum-based combination regimens as bedrock of first-line treatment. Recently, immunotherapy and target therapy are gaining a foothold in the treatment of metastatic disease, with pembrolizumab and atezolizumab showing encouraging results in combination with chemotherapy as a first-line strategy. Moreover, atezolizumab performed well as a maintenance treatment, while pembrolizumab as a single agent achieved promising outcomes in second-line setting. Regarding the target therapy, erdafitinib, a fibroblast growth factor receptor inhibitor, and enfortumab vedotin, an antibody-drug conjugate, proved to have a strong antitumor property, likely due to the distinctive immune-genetic background of UTUC. In this context, great efforts have been addressed to uncover the biological, immunological, and clinical grounds in UTUC patients in order to achieve a personalized treatment.

Adjuvant Radiotherapy for Upper Tract Urothelial Carcinoma: Systematic Review and Meta-Analysis

PURPOSE

Upper tract urothelial carcinoma (UTUC) is a rare form of malignancy comprising only 5% of urothelial cancers. The mainstay of treatment is radical nephroureterectomy (RNU) with bladder cuff excision. Neoadjuvant or adjuvant chemotherapy is often used in locally advanced disease. The role of adjuvant radiotherapy (RT), however, remains controversial. To further explore the potential role of adjuvant RT, we performed a systematic review and meta-analysis of the literature from 1990 to present.

METHODS AND MATERIALS

We identified 810 candidate articles from database searches, of which 67 studies underwent full-text review, with final inclusion of 20 eligible studies. Among the included studies, there were no randomized controlled trials and a single prospective trial, with the remainder being retrospective series. We performed quantitative synthesis of the results by calculating the pooled odds ratios (OR) for the primary outcome of locoregional recurrence (LRR) and secondary outcomes of overall survival (OS), cancer-specific survival (CSS) and distant recurrence (DR).

RESULTS

Adjuvant RT, which was mostly prescribed for locally advanced or margin-positive disease following RNU, significantly reduced locoregional recurrence risk OR 0.43 (95% CI: 0.23-0.70), and the effect remained significant even following subgroup analysis to account for adjuvant systemic therapy. The effect of adjuvant RT on 3-year OS, 5-year CSS and DR was non-significant. However, 5-year OS was unfavourable in the adjuvant RT arm, but study heterogeneity was high, and analysis of small-study effects and subgroups suggested bias in reporting of outcomes.

CONCLUSIONS

Adjuvant RT in the setting of locally advanced UTUC improves locoregional control following definitive surgery, but does not appear to improve OS. Higher-quality studies, ideally randomized controlled trials, are needed to further quantify its benefit in this setting, and to explore multi-modal treatments that include systemic agents given concomitantly or sequentially with RT, which may offer an OS benefit in addition to the locoregional control benefit of RT.

Single-cell and spatial mapping Identify cell types and signaling Networks in the human ureter

Tissue engineering offers a promising treatment strategy for ureteral strictures, but its success requires an in-depth understanding of the architecture, cellular heterogeneity, and signaling pathways underlying tissue regeneration. Here, we define and spatially map cell populations within the human ureter using single-cell RNA sequencing, spatial gene expression, and immunofluorescence approaches. We focus on the stromal and urothelial cell populations to enumerate the distinct cell types composing the human ureter and infer potential cell-cell communication networks underpinning the bi-directional crosstalk between these compartments. Furthermore, we analyze and experimentally validate the importance of the sonic hedgehog (SHH) signaling pathway in adult progenitor cell maintenance. The SHH-expressing basal cells support organoid generation in vitro and accurately predict the differentiation trajectory from basal progenitor cells to terminally differentiated umbrella cells. Our results highlight the essential processes involved in adult ureter tissue homeostasis and provide a blueprint for guiding ureter tissue engineering.

The origin of bladder cancer from mucosal field effects

Whole-organ mapping was used to study molecular changes in the evolution of bladder cancer from field effects. We identified more than 100 dysregulated pathways, involving immunity, differentiation, and transformation, as initiators of carcinogenesis. Dysregulation of interleukins signified the involvement of inflammation in the incipient phases of the process. An aberrant methylation/expression of multiple HOX genes signified dysregulation of the differentiation program. We identified three types of mutations based on their geographic distribution. The most common were mutations restricted to individual mucosal samples that targeted uroprogenitor cells. Two types of mutations were associated with clonal expansion and involved large areas of mucosa. The α mutations occurred at low frequencies while the β mutations increased in frequency with disease progression. Modeling revealed that bladder carcinogenesis spans 10-15 years and can be divided into dormant and progressive phases. The progressive phase lasted 1-2 years and was driven by β mutations.

The urothelium: a multi-faceted barrier against a harsh environment

All mucosal surfaces must deal with the challenge of exposure to the outside world. The urothelium is a highly specialized layer of stratified epithelial cells lining the inner surface of the urinary bladder, a gruelling environment involving significant stretch forces, osmotic and hydrostatic pressures, toxic substances, and microbial invasion. The urinary bladder plays an important barrier role and allows the accommodation and expulsion of large volumes of urine without permitting urine components to diffuse across. The urothelium is made up of three cell types, basal, intermediate, and umbrella cells, whose specialized functions aid in the bladder's mission. In this review, we summarize the recent insights into urothelial structure, function, development, regeneration, and in particular the role of umbrella cells in barrier formation and maintenance. We briefly review diseases which involve the bladder and discuss current human urothelial in vitro models as a complement to traditional animal studies.

Patient-Derived Upper Tract Urothelial Carcinoma Organoids as a Platform for Drug Screening

Upper tract urothelial carcinomas (UTUCs) are rare entities that are usually diagnosed at advanced stages. Research on UTUC pathobiology and clinical management has been hampered by the lack of models accurately reflecting disease nature and diversity. In this study, a modified organoid culture system is used to generate a library of 25 patient-derived UTUC organoid lines retaining the histological architectures, marker gene expressions, genomic landscapes, and gene expression profiles of their parental tumors. The study demonstrates that the responses of UTUC organoids to anticancer drugs can be identified and the model supports the exploration of novel treatment strategies. This work proposes a modified protocol for generating patient-derived UTUC organoid lines that may help elucidate UTUC pathophysiology and assess the responses of these diseases to various drug therapies in personalized medicine.

Initial Evaluation of Uroplakins UPIIIa and UPII in Selected Benign Urological Diseases

BACKGROUND

Uroplakins (UPs) are glycoproteins that play a specific role in the structure and function of the urothelium. Disorders which affect the normal expression of UPs are associated with the pathogenesis of infections and neoplasms of the urinary tract, primary vesicoureteral reflux, hydronephrosis and renal dysfunction. The appearance of uroplakins in the urine and/or plasma may be of potential importance in the detection of urinary tract dysfunction. The aim of the present study was to investigate uroplakin IIIa (UPIIIa) and uroplakin II (UPII) expression in patients with selected urological diseases.

METHODS

Plasma and urine from patients with benign prostatic hyperplasia (BPH), urethral stricture (US), urinary tract infection (UTI) and urolithiasis were compared to healthy people without urological disorders. UPs concentrations were measured by the immunoenzymatic method.

RESULTS

In patients with BPH and UTI, concentrations of UPIIIa in urine and plasma, as well as UPII in urine, were statistically significantly higher than in the control groups. In the US group, only the plasma UPIIIa concentration differed significantly from the control.

CONCLUSION

The conducted research shows that benign urological diseases may affect the state of the urothelium, as manifested by increased concentrations of both UPs in patients' urine and plasma, especially in BPH and UTI.

The Urothelium: Life in a Liquid Environment

The urothelium, which lines the renal pelvis, ureters, urinary bladder, and proximal urethra, forms a high-resistance but adaptable barrier that surveils its mechanochemical environment and communicates changes to underlying tissues including afferent nerve fibers and the smooth muscle. The goal of this review is to summarize new insights into urothelial biology and function that have occurred in the past decade. After familiarizing the reader with key aspects of urothelial histology, we describe new insights into urothelial development and regeneration. This is followed by an extended discussion of urothelial barrier function, including information about the roles of the glycocalyx, ion and water transport, tight junctions, and the cellular and tissue shape changes and other adaptations that accompany expansion and contraction of the lower urinary tract. We also explore evidence that the urothelium can alter the water and solute composition of urine during normal physiology and in response to overdistension. We complete the review by providing an overview of our current knowledge about the urothelial environment, discussing the sensor and transducer functions of the urothelium, exploring the role of circadian rhythms in urothelial gene expression, and describing novel research tools that are likely to further advance our understanding of urothelial biology.

Roles for urothelium in normal and aberrant urinary tract development

Congenital anomalies of the kidney and urinary tract (CAKUTs) represent the leading cause of chronic kidney disease and end-stage kidney disease in children. Increasing evidence points to critical roles for the urothelium in the developing urinary tract and in the genesis of CAKUTs. The involvement of the urothelium in patterning the urinary tract is supported by evidence that CAKUTs can arise as a result of abnormal urothelial development. Emerging evidence indicates that congenital urinary tract obstruction triggers urothelial remodelling that stabilizes the obstructed kidney and limits renal injury. Finally, the diagnostic potential of radiological findings and urinary biomarkers derived from the urothelium of patients with CAKUTs might aid their contribution to clinical care.

Urine Composition in Pigs is Regulated in Both the Ureter and the Bladder

The former perception of the urothelium as an impermeable barrier has been revised during the last decade, as increasing evidence of changes in urine composition during its passage of the urinary tract has been presented. Since differences in urothelial permeability between upper and lower urinary tract have been found, our aim is to demonstrate whether changes in urine composition occur during passage through the ureter. We studied consecutive urine samples from both renal pelvises in six pigs and compared them to samples from the bladder and distal ureter. We further sampled urine during storage in the bladder at a fixed volume. All samples were analysed by measuring osmolality and pH, along with the concentration of the following parameters: Na+, K+, Cl-, creatinine, urea. Urine alkalinity increased significantly during passage of the ureter. Creatinine concentration, pH and K+ increased significantly during the passage from pelvis to the bladder. All other parameters increased non-significantly during the passage to the bladder. The increase in concentration was more pronounced at low concentrations in the pelvis. During storage in the bladder, there was a significant increase in urea concentration. Changes in the composition of urine occur during its passage from the renal pelvis to the bladder and during storage in the bladder. Despite the brief transit time, significant changes in alkalinity were found already during passage through the ureter.

ENaC in Cholinergic Brush Cells

Cholinergic polymodal chemosensory cells in the mammalian urethra (urethral brush cells = UBC) functionally express the canonical bitter and umami taste transduction signaling cascade. Here, we aimed to determine whether UBC are functionally equipped for the perception of salt through ENaC (epithelial sodium channel). Cholinergic UBC were isolated from ChAT-eGFP reporter mice (ChAT = choline acetyltransferase). RT-PCR showed mRNA expression of ENaC subunits Scnn1a, Scnn1b, and Scnn1g in urethral epithelium and isolated UBC. Scnn1a could also be detected by next generation sequencing in 4/6 (66%) single UBC, two of them also expressed the bitter receptor Tas2R108. Strong expression of Scnn1a was seen in some urothelial umbrella cells and in 65% of UBC (30/46 cells) in a Scnn1a reporter mouse strain. Intracellular [Ca²⁺] was recorded in isolated UBC stimulated with the bitter substance denatonium benzoate (25 mM), ATP (0.5 mM) and NaCl (50 mM, on top of 145 mM Na⁺ and 153 mM Cl⁻ baseline in buffer); mannitol (150 mM) served as osmolarity control. NaCl, but not mannitol, evoked an increase in intracellular [Ca²⁺] in 70% of the tested UBC. The NaCl-induced effect was blocked by the ENaC inhibitor amiloride (IC₅₀ = 0.47 μM). When responses to both NaCl and denatonium were tested, all three possible positive response patterns occurred in a balanced distribution: 42% NaCl only, 33% denatonium only, 25% to both stimuli. A similar reaction pattern was observed with ATP and NaCl as test stimuli. About 22% of the UBC reacted to all three stimuli. Thus, NaCl evokes calcium responses in several UBC, likely involving an amiloride-sensitive channel containing α-ENaC. This feature does not define a new subpopulation of UBC, but rather emphasizes their polymodal character. The actual function of α-ENaC in cholinergic UBC—salt perception, homeostatic ion transport, mechanoreception—remains to be determined.

Perioperative chemotherapy for urothelial carcinoma of the upper urinary tract: A systematic review and meta-analysis

INTRODUCTION

Upper tract urothelial carcinomas are rare malignancies with differences in anatomy and biology requiring therapeutic strategies that differ from bladder cancer. The role of perioperative systemic therapy in this disease remains uncertain with limited data to support its use. A systematic review of the literature and meta-analysis was therefore undertaken to provide more information and guide clinical practice.

METHODS

A literature search was performed using Embase and Medline databases with additional searches performed manually using terms associated with upper tract urothelial malignancies. Data was extracted from studies of patients that underwent nephrouretectomy for the management of upper tract urothelial carcinoma and received either neoadjuvant or adjuvant systemic therapy. Overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS) were summated and analyzed using Cochrane Revman software Version 5.3.

RESULTS

There were 13 comparative studies and no randomized studies identified for data extraction; 11 adjuvant and 2 neoadjuvant with 1170 patients receiving perioperative systemic therapy and 3472 controls that did not. Perioperative chemotherapy was associated with improved OS (HR 0.75, 95%CI 0.57-0.99), DFS (HR 0.54, 95%CI 0.32-0.92), and CSS (HR 0.69, 95%CI 0.42-1.15).

CONCLUSIONS

The available data suggests that perioperative systemic therapy is associated with improved survival in patients with upper tract urothelial cancer.

Molecular mechanisms of development of the human fetal female reproductive tract

Human female reproductive tract development rests mostly upon hematoxilyn and eosin stained sections despite recent advances on molecular mechanisms in mouse studies. We report application of immunohistochemical methods to explore the ontogeny of epithelial and mesenchymal differentiation markers (keratins, homobox proteins, steroid receptors), transcription factors and signaling molecules (TP63 and RUNX1) during human female reproductive tract development. Keratins 6, 7, 8, 10, 14 and 19 (KRT6, KRT7, KRT8, KRT10, KRT14, KRT19) were expressed in a temporally and spatially dynamic fashion. The undifferentiated Müllerian duct and uterovaginal canal, lined by simple columnar epithelia, expressed KRT7, KRT8 and KRT19. Glandular derivatives of the Müllerian duct (uterine tube, uterine corpus and endocervix) maintained expression of these keratins, while tissues that undergo stratified squamous differentiation (exocervix and vagina) expressed KRT6, KRT14 and KRT10 during development in an age-dependent fashion. TP63 and RUNX1 were expressed prior to KRT14, as these two transcription factors are known to be upstream from KRT14 in developing Müllerian epithelium. In the vagina, KRT10, a marker of terminal differentiation, appeared after endogenous estrogens transformed the epithelium to a thick glycogenated squamous epithelium. Uroplakin, a protein unique to urothelium, was expressed only in the bladder, urethra and vaginal introitus, but not in the female reproductive tract itself. Mesenchymal differentiation was examined through immunostaining for HOXA11 (expressed in uterine mesenchyme) and ISL1 (expressed in vaginal mesenchyme). A detailed ontogeny of estrogen receptor alpha (ESR1), progesterone receptor (PGR) and the androgen receptor (AR) provides the mechanistic underpinning for the teratogenicity of estrogens, progestins and androgens on female reproductive tract development. Immunohistochemical analysis of differentiation markers and signaling molecules advance our understanding of normal development of the human female reproductive tract. These observations demonstrate remarkable similarities in mouse and human female reproductive tract development, but also highlight some key differences.

Upper tract urothelial carcinoma: a different disease entity in terms of management

Upper tract urothelial carcinomas (UTUCs) consist of 5%–10% of all urothelial carcinomas, the rest being urothelial carcinomas of the bladder (UCB). There is increasing evidence to show that UTUC is a distinct disease entity from UCB based on phenotypical and genotypical (genetic and epigenetic) differences. This may account for why the natural history of UTUC is different from that of UCB, with >60% of UTUCs and only 15%–25% of UCB presenting with invasion at diagnosis. Management of UTUC is thus different from UCB in a variety of ways, ranging from surgical management, postoperative instillation therapy, postoperative surveillance and medical management (neoadjuvant and adjuvant chemotherapy). This review paper aims to highlight these differences with an emphasis on the distinct management of UTUC, along with the latest updates.

L1CAM in the Early Enteric and Urogenital System

L1 cell adhesion molecule (L1CAM) is a transmembrane molecule belonging to the L1 protein family. It has shown to be a key player in axonal guidance in the course of neuronal development. Furthermore, L1CAM is also crucial for the establishment of the enteric and urogenital organs and is aberrantly expressed in cancer originating in these organs. Carcinogenesis and embryogenesis follow a lot of similar molecular pathways, but unfortunately, comprehensive data on L1CAM expression and localization in human developing organs are lacking so far. In the present study we, therefore, examined the spatiotemporal distribution of L1CAM in the early human fetal period (weeks 8-12 of gestation) by means of immunohistochemistry and in situ hybridization (ISH). In the epithelia of the gastrointestinal organs, L1CAM localization cannot be observed in the examined stages most likely due to their advanced polarization and differentiation. Despite these results, our ISH data indicate weak L1CAM expression, but only in few epithelial cells. The genital tracts, however, are distinctly L1CAM positive throughout the entire fetal period. We, therefore, conclude that in embryogenesis L1CAM is crucial for further differentiation of epithelia.

Anatomy and Physiology of the Urinary Tract: Relation to Host Defense and Microbial Infection

The urinary tract exits to a body surface area that is densely populated by a wide range of microbes. Yet, under most normal circumstances, it is typically considered sterile, i.e., devoid of microbes, a stark contrast to the gastrointestinal and upper respiratory tracts where many commensal and pathogenic microbes call home. Not surprisingly, infection of the urinary tract over a healthy person's lifetime is relatively infrequent, occurring once or twice or not at all for most people. For those who do experience an initial infection, the great majority (70% to 80%) thankfully do not go on to suffer from multiple episodes. This is a far cry from the upper respiratory tract infections, which can afflict an otherwise healthy individual countless times. The fact that urinary tract infections are hard to elicit in experimental animals except with inoculum 3-5 orders of magnitude greater than the colony counts that define an acute urinary infection in humans (105 cfu/ml), also speaks to the robustness of the urinary tract defense. How can the urinary tract be so effective in fending off harmful microbes despite its orifice in a close vicinity to that of the microbe-laden gastrointestinal tract? While a complete picture is still evolving, the general consensus is that the anatomical and physiological integrity of the urinary tract is of paramount importance in maintaining a healthy urinary tract. When this integrity is breached, however, the urinary tract can be at a heightened risk or even recurrent episodes of microbial infections. In fact, recurrent urinary tract infections are a significant cause of morbidity and time lost from work and a major challenge to manage clinically. Additionally, infections of the upper urinary tract often require hospitalization and prolonged antibiotic therapy. In this chapter, we provide an overview of the basic anatomy and physiology of the urinary tract with an emphasis on their specific roles in host defense. We also highlight the important structural and functional abnormalities that predispose the urinary tract to microbial infections.

Uroplakin II is a more sensitive immunohistochemical marker than uroplakin III in urothelial carcinoma and its variants

OBJECTIVES

Uroplakin (UP) II and UPIII are highly specific immunohistochemical markers for urothelial differentiation. Here we studied the sensitivity of UPII and UPIII in conventional and variant urothelial carcinomas (UCs).

METHODS

Immunohistochemical staining for UPII and UPIII was performed on tissue microarray slides, including 105 conventional bladder UCs (BUCs), 90 upper urinary tract UCs (UUTUCs), and 47 micropapillary, 16 plasmacytoid, 22 small cell carcinoma, and 41 sarcomatoid UC variants.

RESULTS

UPII expression was significantly higher than UPIII expression in conventional BUC (44% vs 17%, P < .001) and UUTUC (67% vs 46%, P = .045). UPIII expression was significantly higher in UUTUC than in BUC (P < .001). In UC variants, UPII expression was significantly higher than UPIII expression in micropapillary (91% vs 25%, P < .001), plasmacytoid (63% vs 6%, P < .001), and sarcomatoid (29% vs 5%, P = .032) variants. Only rare cases of the small cell carcinoma variant had focal UPII and UPIII expression. Compared with conventional UC, the sarcomatoid variant had significantly lower UPII expression, whereas the micropapillary variant had significantly higher UPII expression (P < .001).

CONCLUSIONS

UPII demonstrates a significantly higher sensitivity than UPIII in conventional and variant UCs. Thus, UPII is a more valuable marker than UPIII in immunohistochemical analyses for confirming the urothelial origin of carcinomas.

Comparison of urine cytology and fluorescence in situ hybridization in upper urothelial tract samples

BACKGROUND

The cytologic diagnosis of urothelial carcinoma (UC) of the upper urothelial tract (UT) is challenging. Using the UroVysion probe set adds diagnostic value for the detection of bladder cancer in voided urine. In instrumented UT specimens, the authors encountered positive UT cytology and fluorescence in situ hybridization (FISH) cases that did not demonstrate subsequent UT carcinoma.

METHODS

The performance of cytology and FISH in the presence or absence of concomitant bladder cancer within 2 years was compared in 61 patients (112 samples) from 2003 through 2009. The mean follow-up was 3.2 years. The authors also compared the performance of near-tetrasomy versus hypertetrasomy. Biopsy confirmation of UTUC in 21 patients was considered the gold standard.

RESULTS

Cytology alone was found to be poorly sensitive (38%) but highly specific (89%) for the detection of UTUC. FISH was found to increase the sensitivity of cytology and decrease specificity. Tetrasomy FISH resulted in many false-positive cases. Other false-positive FISH results were likely due to the presence of bladder cancer cells contaminating the UT specimen.

CONCLUSIONS

Caution should be used when evaluating instrumented urine specimens of the UT from patients with a previous history of bladder carcinoma, and tetrasomy FISH results should not be interpreted as abnormal because it significantly lowers the specificity of the test. The combination of cytology and FISH appears to have good specificity while maintaining good sensitivity in evaluating UTUC when using modified scoring criteria for the appropriate patient population.

Application of systems biology principles to protein biomarker discovery: urinary exosomal proteome in renal transplantation

PURPOSE

In mass spectrometry (MS)-based studies to discover urinary protein biomarkers, an important question is how to analyze the data to find the most promising potential biomarkers to be advanced to large-scale validation studies. Here, we describe a "systems biology-based" approach to address this question.

EXPERIMENTAL DESIGN

We analyzed large-scale liquid chromatography-tandem mass spectrometry (LC-MS/MS) data of urinary exosomes from renal allograft recipients with biopsy-proven evidence of immunological rejection or tubular injury (TI). We asked whether bioinformatic analysis of urinary exosomal proteins can identify biological-process based protein groups that correlate with biopsy findings and whether the protein groups fit with general knowledge of the pathophysiological mechanisms involved.

RESULTS

LC-MS/MS analysis of urinary exosomal proteomes identified more than 1000 proteins in each pathologic group. These protein lists were analyzed computationally to identify the Biological Process and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway terms that are significantly associated with each pathological group. Among the most informative terms for each group were: "sodium ion transport" for TI; "immune response" for all rejection; "epithelial cell differentiation" for cell-mediated rejection; and "acute inflammatory response" for antibody-mediated rejection. Based on these terms, candidate biomarkers were identified using a novel strategy to allow a dichotomous classification between different pathologic categories.

CONCLUSIONS AND CLINICAL RELEVANCE

The terms and candidate biomarkers identified make rational connections to pathophysiological mechanisms, suggesting that the described bioinformatic approach will be useful in advancing large-scale biomarker identification studies toward a validation phase.

Randomized phase III study comparing paclitaxel/cisplatin/gemcitabine and gemcitabine/cisplatin in patients with locally advanced or metastatic urothelial cancer without prior systemic therapy: EORTC Intergroup Study 30987

PURPOSE

The combination of gemcitabine plus cisplatin (GC) is a standard regimen in patients with locally advanced or metastatic urothelial cancer. A phase I/II study suggested that a three-drug regimen that included paclitaxel had greater antitumor activity and might improve survival.

PATIENTS AND METHODS

We conducted a randomized phase III study to compare paclitaxel/cisplatin/gemcitabine (PCG) with GC in patients with locally advanced or metastatic urothelial carcinoma. Primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS), overall response rate, and toxicity.

RESULTS

From 2001 to 2004, 626 patients were randomly assigned; 312 patients were assigned to PCG, and 314 patients were assigned to GC. After a median follow-up of 4.6 years, the median OS was 15.8 months on PCG versus 12.7 months on GC (hazard ratio [HR], 0.85; P = .075). OS in the subgroup of all eligible patients was significantly longer on PCG (3.2 months; HR, 0.82; P = .03), as was the case in patients with bladder primary tumors. PFS was not significantly longer on PCG (HR, 0.87; P = .11). Overall response rate was 55.5% on PCG and 43.6% on GC (P = .0031). Both treatments were well tolerated, with more thrombocytopenia and bleeding on GC than PCG (11.4% v 6.8%, respectively; P = .05) and more febrile neutropenia on PCG than GC (13.2% v 4.3%, respectively; P < .001).

CONCLUSION

The addition of paclitaxel to GC provides a higher response rate and a 3.1-month survival benefit that did not reach statistical significance. Novel approaches will be required to obtain major improvements in survival of incurable urothelial cancer.

Formation and maintenance of blood-urine barrier in urothelium

Blood-urine barrier, which is formed during differentiation of superficial urothelial cells, is the tightest and most impermeable barrier in the body. In the urinary bladder, the barrier must accommodate large changes in the surface area during distensions and contractions of the organ. Tight junctions and unique apical plasma membrane of superficial urothelial cells play a critical role in the barrier maintenance. Alterations in the blood-urine barrier function accompany most of the urinary tract diseases. In this review, we discuss recent discoveries on the role of tight junctions, dynamics of Golgi apparatus and post-Golgi compartments, and intracellular membrane traffic during the biogenesis and maintenance of blood-urine barrier.

Cell biology and physiology of the uroepithelium

The uroepithelium sits at the interface between the urinary space and underlying tissues, where it forms a high-resistance barrier to ion, solute, and water flux, as well as pathogens. However, the uroepithelium is not simply a passive barrier; it can modulate the composition of the urine, and it functions as an integral part of a sensory web in which it receives, amplifies, and transmits information about its external milieu to the underlying nervous and muscular systems. This review examines our understanding of uroepithelial regeneration and how specializations of the outermost umbrella cell layer, including tight junctions, surface uroplakins, and dynamic apical membrane exocytosis/endocytosis, contribute to barrier function and how they are co-opted by uropathogenic bacteria to infect the uroepithelium. Furthermore, we discuss the presence and possible functions of aquaporins, urea transporters, and multiple ion channels in the uroepithelium. Finally, we describe potential mechanisms by which the uroepithelium can transmit information about the urinary space to the other tissues in the bladder proper.

Uroplakins in urothelial biology, function, and disease

Urothelium covers the inner surfaces of the renal pelvis, ureter, bladder, and prostatic urethra. Although morphologically similar, the urothelia in these anatomic locations differ in their embryonic origin and lineages of cellular differentiation, as reflected in their different uroplakin content, expandability during micturition, and susceptibility to chemical carcinogens. Previously thought to be an inert tissue forming a passive barrier between the urine and blood, urothelia have recently been shown to have a secretory activity that actively modifies urine composition. Urothelial cells express a number of ion channels, receptors, and ligands, enabling them to receive and send signals and communicate with adjoining cells and their broader environment. The urothelial surface bears specific receptors that not only allow uropathogenic E. coli to attach to and invade the bladder mucosa, but also provide a route by which the bacteria ascend through the ureters to the kidney to cause pyelonephritis. Genetic ablation of one or more uroplakin genes in mice causes severe retrograde vesicoureteral reflux, hydronephrosis, and renal failure, conditions that mirror certain human congenital diseases. Clearly, abnormalities of the lower urinary tract can impact the upper tract, and vice versa, through the urothelial connection. In this review, we highlight recent advances in the field of urothelial biology by focusing on the uroplakins, a group of urothelium-specific and differentiation-dependent integral membrane proteins. We discuss these proteins' biochemistry, structure, assembly, intracellular trafficking, and their emerging roles in urothelial biology, function, and pathological processes. We also call attention to important areas where greater investigative efforts are warranted.

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.

Using LongSAGE to Detect Biomarkers of Cervical Cancer Potentially Amenable to Optical Contrast Agent Labelling

Sixteen longSAGE libraries from four different clinical stages of cervical intraepithelial neoplasia have enabled us to identify novel cell-surface biomarkers indicative of CIN stage. By comparing gene expression profiles of cervical tissue at early and advanced stages of CIN, several genes are identified to be novel genetic markers. We present fifty-six cell-surface gene products differentially expressed during progression of CIN. These cell surface proteins are being examined to establish their capacity for optical contrast agent binding. Contrast agent visualization will allow real-time assessment of the physiological state of the disease process bringing vast benefit to cancer care. The data discussed in this publication have been submitted to NCBIs Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/ ) and are accessible through GEO Series accession number GSE6252.

The Physiological Function of the Urothelium – More than a Simple Barrier

The urothelium, the epithelium lining the surface of the urinary bladder, is a unique cell type with high plasticity and a variety of cellular functions. The urothelium represents the first line of bladder defense and an interface between pathogens and defense mechanisms. Functions of the urothelium include control of permeability, immune responses and cell-cell communication, which seems to play a pivotal role in responding to injuries and infections. The urothelium responds to stretch, during the filling phase of micturition reflex, by increasing the size of apical umbrella cells and by releasing mediators which activate the sensory fibers. For this reason the concept of 'neuron-like properties' was suggested. Finally, despite the fact that the urothelium is a frequent site of cancer formation, few experimental model systems are currently available or well characterized for studying urothelial cancer in the era of genomics and proteomics. The purpose of this review is to give emphasis to urothelial physiology and pathophysiology in different bladder disorders and to offer an up-to-date contribution to the field of urothelial research.

The complexus adhaerens of mammalian lymphatic endothelia revisited: a junction even more complex than hitherto thought

The significance of a special kind of VE-cadherin-based, desmoplakin- and plakoglobin-containing adhering junction, originally identified in certain endothelial cells of the mammalian lymphatic system (notably the retothelial cells of the lymph node sinus and a subtype of lining endothelial cells of peripheral lymphatic vessels), has been widely confirmed and its importance in the formation of blood and lymph vessels has been demonstrated in vivo and in vitro. We have recently extended the molecular and structural characterization of the complexus adhaerens and can now report that it represents a rare and special combination of components known from three other major types of cell junction. It comprises zonula adhaerens proteins (VE-cadherin, alpha- and beta-catenin, protein p120(ctn), and afadin), desmosomal plaque components (desmoplakin and plakoglobin), and tight-junction proteins (claudin-5 and ZO-1) and forms junctions that vary markedly in size and shape. The special character and the possible biological roles of the complexus adhaerens and its unique ensemble of molecules in angiogenesis, immunology, and oncology are discussed. The surprising finding of claudin-5 and protein ZO-1 in substructures of retothelial cell-cell bridges, i.e. structures that do not separate different tissues or cell layer compartments, suggests that such tight-junction molecules are involved in functions other than the "fence" and "barrier" roles of zonulae occludentes.

Distribution of junction- and differentiation-related proteins in urothelial cells at the leading edge of primary explant outgrowths

Leading edge cells, which are located at the forefront of a wound margin, play a significant role in coordinating the wound healing process. In this study, leading edge cells of the urothelial explant outgrowth, resembling leading edge cells during urothelial full-thickness wound healing in vivo, were analyzed for expression and distribution of junction and differentiation-related proteins. Ultrastructural and immunofluorescence studies revealed that urothelial cells at the leading edge expressed ZO-1, claudin-4, occludin, E-cadherin, cytokeratin 7 and cytokeratin 20, while no expression of claudin-8 was noted. ZO-1, claudin-4, occludin and E-cadherin were localized along the cell membranes where neighbouring leading edge cells were in contact. Cytokeratin 7 was detected as filaments and cytokeratin 20 as small dots and sparse filaments. In conclusion, we detected early expression of ZO-1, claudin-4 and occludin at the urothelial leading edge, predicating the later formation of tight junctions as a necessary stage for the differentiation process that subsequently begins. The expression of occludin and cytokeratin 20 in urothelial cells at the leading edge suggests that leading edge cells may develop into fully differentiated superficial cells.