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“Urothelial Cell Physiology in
Normal and Disease States” http://www.urothelium2005.com a Satellite
Symposium to the International Physiology, 2005 (San Diego- March 29-30,
2005).
This was a well-balanced group of outstanding speakers who addressed key
issues of lower urinary tract physiology and dysfunction. Thirty five
speakers (21 males and 14 females) have participated. Among those, 40
percent were from abroad (Australia, Denmark, France, Italy, Netherlands,
Sweden, and UK).
The symposium specific objectives were to review bladder physiology and to
discuss the principal aspects of lower urinary tract dysfunction, including:
detrusor instability, stress incontinence, interstitial cystitis, bladder
cancer, infection, inflammation, and immunity. In addition, the participants
sought to identify new post-genomic research approaches.
The symposium specific goals were to attract new scientists to this
important area of research and to stimulate the participation of
postdoctoral fellows and graduate students by providing travel awards for
selected poster presentations. More than 100 attendees, mostly young
investigators, participated in this meeting and 43 posters were presented.
A sensory role for the urothelium. A sensory role for the urothelium. Lori
Birder (University of Pittsburgh) presented data demonstrating a sensory
function for the urothelium. Although the urinary bladder urothelium has
classically been thought of as a passive barrier to ions/solutes, a number
of novel properties have been recently attributed to these cells. Studies
have revealed that the urothelium is involved in sensory mechanisms (i.e.,
ability to express a number of sensor molecules including TRPV1 or respond
to thermal, mechanical, and chemical stimuli) and can release chemical
mediators (nitric oxide; ATP). Localization of afferent nerves next to the
urothelium suggests these cells may be targets for transmitters released
from bladder nerves or that chemicals released by urothelial cells may alter
afferent excitability. Research priorities: elucidation of mechanisms
impacting on urothelial function may provide insights into the pathology of
bladder dysfunction.
Role of the bladder urothelial cell in sensory signal transduction using
interstitial cystitis as a human model. Toby Chai (University of Maryland)
presented results indicating that human interstitial cystitis (IC)
urothelial cells persist with an abnormal phenotype within a cultured in
vitro system. The theory of augmented purinergic signal transduction in IC
bladder urothelial cells has been supported by several observations
including augmented ATP release and increased expression of P2X3/P2X2
receptors. Patch-clamp electrophysiological studies of both normal and IC
urothelial cells revealed a persistent altered phenotype in IC urothelial
cells with decreased activity of Kir2.1 inward rectifying potassium current
in the IC cells. Research priorities: to determine whether the altered
phenotype in ion-channel function relates to increased bladder sensory
signaling.
P2X receptors and ATP regulation of urinary bladder function. Debra Cockayne
(Roche Bioscience) presented results indicating that distension of the
urinary bladder results in release of ATP from the urothelium and excitation
of P2X3 receptors on adjacent primary sensory neurons. More recently, the
role of P2X3 and P2X2/3 receptors in urinary bladder function was defined by
using P2X3 KO, P2X2 KO and P2X2/P2X3 double KO mice. Activation of P2X3
and/or P2X2/3 receptors on bladder afferent terminals are important in
mechanosensation and represent a critical step in sensing bladder filling
information under anesthesia, or following capsaicin or inflammation,
suggesting an important action of ATP acting via a c-fiber mediated reflex
pathway. Research priorities: defining the role of P2X3 and P2X2/3 receptors
in mediating sensory fiber dependent responses in models of bladder function
and pain transmission. Lastly, significant advances must be made in
developing safe and effective small molecule antagonists to P2X3 receptors
if preclinical research in this area is to advance to the clinic.
Cystitis-Induced Plasticity of Micturition Reflexes. Margaret Vizzard
(University of Vermont) described effects of cyclophosphamide (CYP)-induced
cystitis on two downstream transcription factors, CREB and c-Jun in dorsal
root ganglia (DRG). Also discussed were the effects of a recombinant NGF
sequestering protein (REN1820) on lower urinary tract reflexes with
cystitis. Research priorities: 1) Additional characterization of NGF and
BDNF in sensory innervation (afferent and urothelium) to the bladder in the
context of cystitis; 2) Additional characterization of NGF and BDNF effects
on the efferent limb of the micturition reflex; 3) Development of additional
tools directed at neurotrophins and neurotrophin receptors.
Plasticity of bladder sensory and motor nerves: the role of neurotrophins
and steroids. Janet Keast (University of Sydney, Australia) emphasized that
in adult female rats many bladder afferent neurons express estrogen
receptors (ERs) co-localized with TRPV1. This raises the possibility that
estrogens affect bladder pain by influencing sensory transduction. She
presented results indicating that neurturin, a member of the GDNF family,
plays a role in maintaining these neurons in adult mice. Research
priorities: to reveal new drug targets for modulating responses of bladder
afferent and efferent neurons to tissue damage, inflammation or nerve
injury.
Central processing of nociceptive input from the urinary bladder. Robert D.
Foreman (University of Oklahoma) recorded extracellular action potentials of
lumbosacral spinal neurons to determine their responses to urinary bladder
distension in pentobarbital anesthetized rats with an inflamed or normal
colon. His results show that colitis caused an increase in the sensitization
of lumbosacral spinal neurons receiving input from a “normal urinary
bladder.” Research priorities: to determine the basic neural and humoral
mechanisms involved in visceral cross-sensitization and whether humoral
mechanisms may also have secondary effects on smooth muscle function.
Detrusor Instability–Clinical Perspective. Karl-Erik Andersson (Institute of
Laboratory Medicine, Sweden) discussed the fact that detrusor overactivity
(DO) is an urodynamic diagnosis that may or may not be associated with the
overactive bladder (OAB). DO is defined as “a urodynamic observation
characterized by involuntary detrusor contractions during the filling phase
which may be spontaneous or provoked. DO may be neurogenic (previously
hyperreflexia)—when there is a relevant neurological condition—or
idiopathic—when there is no defined cause. Idiopathic detrusor overactivity
now replaces the term detrusor instability. Treatment options include
conservative bladder retraining, biofeedback, electrical stimulation,
neuromodulation, pharmacotherapy, and, as a last resort, surgery.
Pharmacotherapy is based on blocking bladder muscarinic receptors, but
unfortunately, antimuscarinic treatment is far from optimal. Research
priorities: to define targets and mechanisms for effective therapeutic
interventions.
The cellular basis of contraction in human detrusor smooth muscle from
patients with stable and over-active bladders. Chris Fry (U. College London,
UK) reviewed the role of Ca2+ channels, intracellular Ca-stores, purinergic
mechanisms, and interstitial cells in the over-active bladder. Research
priorities: the identification and characterization of changes to human
detrusor function associated with bladder over-activity including: 1)
Characterization of the control of transmitter function on the detrusor by
pre- and post-synaptic mechanisms; 2) The mechanisms regulating
intracellular Ca2+ homeostasis; 3) The interplay between
electrophysiological and chemical signaling pathways in regulating cellular
and intercellular mechanisms controlling detrusor contractility; and 4) The
regulation of quantal Ca2+ release from intracellular stores.
Overactive bladder and incontinence in the absence of the large conductance
calcium activated potassium (BK) channel. Matthias Werner (University of
Vermont) studied the large conductance and calcium-activated potassium (BK)
channels in the urinary bladder smooth muscle cells of Slo-/- mice; these
mice lack calcium-activated BK currents, but exhibit normal calcium
transients and voltage-dependent potassium currents. In the absence of BK
channels, spontaneous and nerve-evoked contractions of the urinary bladder
were significantly enhanced. Consistent with this increased bladder
contractility, Slo-/- mice demonstrated a marked increase in voiding
frequency coupled with reduced bladder capacity. Furthermore the average
bladder pressure was increased in Slo-/- mice compared to controls, as well
as the frequency of oscillations in bladder pressure. These results revealed
a central role for BK channels in urinary bladder function, and indicated
that BK channel dysfunction leads to overactive bladder and urinary
incontinence. Research priorities: in addition to electrophysiological
studies on isolated myocytes and monitoring of intracellular Ca2+ dynamics,
in vitro and in vivo approaches should be applied on transgenic mice lacking
the BK channel to clarify its role in the urogenital tract.
Functional genomics of detrusor smooth muscle. George J. Christ, (Wake
Forest University) emphasized that functional Genomics provides an important
cornerstone for the new age of molecular medicine, and lends itself to
identifying small molecules and genes that may be of therapeutic utility.
This approach was successfully used to identify targets for gene transfer of
erectile dysfunction and a similar strategy for the treatment of bladder
overactivity is now being pursued. However, in severely diseased tissues,
pharmacological and gene transfer approaches may no longer be feasible, as
the tissue damage is too extensive to permit pharmacological or genetic
manipulation. In such cases, tissue-engineering approaches are utilized for
total tissue/organ replacement. Research priorities: identification of the
mechanistic basis of changes critical to the improved understanding,
diagnosis and treatment of bladder dysfunction leading to urinary
incontinence. Multidisciplinary, translational research approaches are
required to identify, develop and distribute the required technologies. In
this scenario, microarray (gene chip) technologies can be used to identify
the genetic changes in smooth muscle cells that are associated with bladder
dysfunction.
Urothelial-Smooth Muscle Communication as Revealed by Optical Imaging.
Anthony J. Kanai (University of Pittsburgh) described the use of optical
imaging techniques to study detrusor spontaneous activity. A dual photodiode
array system was developed to simultaneously record action potentials and
Ca2+ transients from 256 sites across the bladder wall. In adult mice,
spontaneous Ca2+ transients are disorganized, arising at multiple sites and
resulting in low amplitude (2-5 cm H2O) contractions. In spinal cord
transected or partially obstructed animals however, pacemaker-like activity
at the dome initiates Ca2+ waves that spread uniformly through the detrusor
resulting in large amplitude (15-25 cm H2O) contractions. Gap junction
blockade (10 mM glycyrrhetinic acid) abolished spontaneous activity in
transected and obstructed mice, but not in adults. IHC revealed that
connexin 43 is localized to lamina propria myofibroblasts (LPM) and connexin
45 to detrusor smooth muscle cells. In transected and obstructed mice, only
connexin 43 was elevated. This suggests that in the pathological bladder,
organized spontaneous activity spreads through gap junctions interconnecting
the LPM and not the smooth muscle cells. The LPM in turn may communicate
with urothelial cells or nerves with which they are in close contact.
Research priorities: to better understand the mechanisms underlying detrusor
overactivity: 1) The involvement of the urothelium, afferent nerves and
smooth muscle cells; 2) The importance of gap junctions and their site of
expression; and 3) The role of lamina propria myofibroblasts and spontaneous
bladder activity.
Functional and Disease Implications of Uroplakins: Lessons from Knockout
Studies. Tung-Tien Sun (New York University) described the apical surface of
the mammalian urothelium which is covered by 16 nm protein particles packed
hexagonally to form 2D crystals of asymmetric unit membranes (AUM); this
structure contributes to the remarkable permeability barrier function of the
urinary bladder. He has previously shown that bovine AUMs contain four major
integral membrane proteins, i.e., uroplakins Ia, Ib, II and III, and that
UPIa and Ib form heterodimers with UPII and III, respectively. Using a panel
of antibodies recognizing different conformational states of uroplakins,
this demonstrates that the UPIa-dependent, furin-mediated cleavage of the
prosequence of UPII leads to global conformational changes in mature UPII,
and that UPIb also induces conformational changes in its partner UPIII.
These results indicate that tetraspanin uroplakins, and possibly other
tetraspanin CD molecules, can induce conformational changes leading to the
ER exit, stabilization and cell-surface expression of their associated,
single-pass partner proteins. A model of AUM assembly was proposed in which
conformational alterations of integral membrane proteins induced by
differentiation-dependent glycosylation and the removal of the prosequence
of UPII play a key role in regulating the assembly of uroplakins to form AUM.
Urothelial permeability. Simon Lewis (University of Texas at Galveston)
emphasized that the prime function of the bladder epithelium is to act as a
barrier between the urine and plasma. The key players in maintaining this
barrier and those candidates that alter this function such as reactive
oxygen species (ROS) were reviewed. Although a number of transgenic animals
are available, methods for studying the urothelial physiology of these
animals is lacking. Research Priorities: what is the molecular basis for the
low permeability of the luminal membrane and tight junctions of the
urothelium? Does the urothelium facilitate communication between the luminal
compartment and the serosal compartment? What receptor families are present
in the urothelium and what is their distribution? How does the urothelium
deal with the leak of urinary constituents into the interstitial space? What
is the response of and the consequences to the urothelium of bladder
inflammation?
ATP and Purinergic Receptor-Dependent Membrane Traffic in Bladder Umbrella
Cells. Gerard Apodaca (University of Pittsburgh) described the umbrella
cells lining the urinary bladder as mechanosensors which participate in the
augmentation of the apical surface area during bladder filling. His data
indicated that increased hydrostatic pressure stimulates the release of ATP
from the uroepithelium, and that upon binding to P2X and possibly P2Y
receptors on the umbrella cells, mobilizes downstream Ca2+ and activates
protein kinase A. This promotes membrane insertion at the apical pole of
umbrella cells. Research Priorities: to better understand membrane
trafficking pathways in polarized epithelial cells, it is necessary to
determine how umbrella cells sense changes in pressure and how these changes
are translated through secondary messenger cascades into vesicle fusion
events followed by membrane recovery through endocytosis.
Signal Transduction in the Bladder. Michael R. Freeman (Harvard University)
identified heparin-binding epidermal growth factor-like growth factor (HB-EGF)
as an urothelial cell and bladder smooth muscle cell (SMC) mitogen that is
synthesized in both the bladder epithelial and muscle tissue compartments.
In published studies it has been shown that following a mechanical stimulus,
HB-EGF gene is upregulated by a mechanism involving angiotensin-, receptor
tyrosine kinase- and mitogen activated protein kinase- (MAPK-) dependent
pathways. HB-EGF localizes to the cell nuclei of transitional cell carcinoma
(TCC); this histologic feature is an indicator of poor prognosis in human
bladder cancer. Recent studies have employed DNA microarray, proteomics, and
organ culture approaches to further understand the signaling processes that
drive pathologic cell and tissue growth in the bladder. Nuclear-localized
HB-EGF can be mobilized into an EGF receptor-dependent autocrine loop in
response to the intracellular production of reactive oxygen species in TCC
cells. Collectively, these studies have shown that HB-EGF is an important
signaling peptide in the bladder in multiple physiologic and
pathophysiologic contexts.
Antiproliferative factor, heparin-binding epidermal growth factor-like
growth factor, and epidermal growth factor in interstitial cystitis. Susan
Keay (University of Maryland) identified an antiproliferative factor in the
urine of interstitial cystitis patients. APF is a small sialylated
glycopeptide whose backbone peptide sequence bears 100% homology to the
sixth transmembrane segment of frizzled 8. It is hypothesized that APF may
cause the bladder epithelial abnormalities associated with IC. It is propose
that APF may be useful as a noninvasive diagnostic biomarker for this
disorder. Research priorities: identification or development of agents that
inhibit the production or activity of APF.
Role of sensory peptides on the physiology of the lower urinary tract.
Karl-Erik Andersson (Institute of Laboratory Medicine, Sweden) discussed the
functional roles of many of the neuropeptides that have been demonstrated to
be synthetized, stored, and released in the human lower urinary tract.
Defining sensory peptides as the peptides found in sensory nerves, the
functional effects of substance P (SP) and other tachykinins, calcitonin
gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and
pituitary adenylyl cyclase activating peptide (PACAP), have been the most
widely investigated. However, the importance of VIP and also of PACAP, which
is often co-localized with VIP, for normal and /or disturbed detrusor
function, remains to be established. It is well known that both the
expression and functional importance of sensory peptides may change by
disease. Future studies of such changes in animal models of, and in patients
with lower urinary tract disorders, are necessary to reveal their roles in
the pathogenesis of disturbances of bladder function, and for identifying
targets for possible therapeutic interventions.
The role of cysteinyl-leukotrienes in cystitis. Kirsten Bouchelouche
(University of Copenhagen, Denmark) presented evidence for the existence of
specific leukotriene D4 (LTD4) receptors in human detrusor smooth muscle
cells. A role of cysteinyl-leukotrienes is supported by the increase in
urinary excretion of LTE4 in patients with interstitial cystitis and
detrusor mastocytosis compared to healthy controls. A pilot study using the
specific LTD4 receptor antagonist SingulairÒ in IC patients with detrusor
mastocytosis, resulted in a significant decrease in voiding frequency and
pain. Future studies should be focused on the role of these factors in mast
cell recruitment and survival in interstitial cystitis.
Urothelium-derived inhibitory factor. Russ Chess-Williams (The Royal
Hallamshire Hospital, UK) presented evidence for an urothelium derived
inhibitory factor (UDIF). Using selective antagonists, it was shown that the
inhibition by UDIF is prevented in the presence of selective M2 but not M3
muscarinic receptor antagonists. This confirms the importance of the M2
receptor subtype in mediating UDIF release. Research Priorities: to identify
the UDIF, to investigate whether its release is altered in the overactive
bladder, and to identify the cells types responsible for producing the
factor.
Tachykinin and vanilloid receptors in human urinary bladder. Elizabeth
Burcher (University of New South Wales, Australia) presented results on the
density of capsaicin (TRPV1) and substance P (neurokinin) receptors in the
bladders of control and sensory urgency (SU) patients. In control patients,
there was a higher expression of TRPV1 in the mucosa compared with the
detrusor. In sensory urgency (SU) patients, there was a higher expression in
the trigone (mucosa) compared with the body (mucosa). As the trigone is
embryologically different from the bladder body, it is hypothesized that
excessive afferent signaling from the trigonal mucosa may be related to an
early first desire to void. The presence of tachykinin NK2 receptor mRNA in
detrusor is in accordance with previous reports of high levels of the
receptor protein.
Tachykinins as modulators of the micturition reflex in the central and
peripheral nervous system. Alessandro Lecci (Menarini Ricerche Firenze,
Italy) presented evidence indicating that tachykinins (TKs) modulate the
afferent arm of the micturition reflex by acting at the peripheral and
spinal cord level. The target of supraspinal modulation remains to be
determined. In addition, clinical studies with TK receptor antagonists
indicate that blockade of this modulation is a suitable therapeutic approach
for the treatment of bladder overactivity.
Interplay between tachykinin, muscarinic and purinergic receptors. Kate
Moore (University of New South Wales, Australia) presented an overview on
idiopathic detrusor overactivity, the second most common cause of urinary
incontinence in women. Integrating the changes that occur in tachykinin,
purinergic, and muscarinic receptor expression in the urothelium and
detrusor of IDO patients will lead to careful characterization of the
clinical and urodynamic features. In addition, it will permit the
classification of patients with predominantly afferent deficit or efferent
deficit.
Visualization of lymphatic vessels through NF-kB activity. Ricardo Saban
(University of Oklahoma) using a transgenic mice with a reporter gene for
NF-kB activity (kB-lacZ) in combination with immunohistochemical staining
with a specific lymphatic marker (LYVE-1), showed, for the first time, that
NF-kB is constitutively active in the lymphatic endothelium of the urinary
bladder (Blood 104: 3228-3230, 2004). This new mouse model permits the
visualization of lymphatics and the definition of the following research
priorities: 1) Determination of the mechanisms involved in lymphatic vessel
proliferation, 2) Characterization of specific pro- and anti-lymphangiogenic
factors, and 3) Determination of the role of lymphatics in bladder
obstruction, inflammation, and cancer.
Functional analysis of the role of NF-kB in vivo using transgenic mice.
Sylvie Memet (Pasteur Institute, France) described NF-kappab as a crucial
transcription factor mainly involved in immune and inflammatory responses,
cell growth and proliferation. This factor is upregulated in a number of
human cancers and diseases. To analyze basal and inducible NF-kB activity
and to understand the impact of its modulation on immune and brain functions
in vivo, several transgenic mouse models has been developed. These various
models, mice with a lacZ reporter gene under the control of kB sites,
knock-out mice for one or several IkBs, or mice over-expressing in a
conditional fashion a transdominant negative mutant of NF-kB
(super-repressor) were presented. Research Priorities: conditional
tissue-specific expression of super-repressor molecules will permit the
elucidation of the role of NF-kB in bladder cancer and inflammation. For
this purpose, we urgently need to develop new transgenic mouse models with a
urothelial-targeted inducible super-repressor.
Cellular Hypoxia-Response Signaling Pathway and its Implications for Human
Bladder Function in Disease States. Ralph Buttyan (Columbia University)
discussed the role of hypoxia-inducible factor (HIF) with regards to the
obstructed bladder, presenting evidence linking activation of the bladder’s
hypoxia response with the hypertrophy. It was shown that this early
hypertrophy is associated with increased bladder vasculogenesis. A follow-up
at longer periods after outlet obstruction shows that the pro-angiogenic
activity associated with the early bladder response to obstruction is
replaced by progressively increased expression of anti-angiogenic substances
that might drive the bladder into the decompensated state. Research
Priorities: to determine whether bladder decompensation might be prevented
by blocking the expression of anti-angiogenic substances and on the
potential long term effects of hypoxia on the differentiated state of
various bladder cell components.
Caught in a storm but not without an umbrella: uropathogenic Escherichia
coli and cystitis. Patrick Seed (Washington University) discussed the
relationship of uropathogenic Escherichia coli (UPEC) with the bladder
epithelium. This represents an outstanding model for understanding acute
pathogen-mucosal interactions. It was also revealed that UPEC has the
capacity to invade the bladder superficial umbrella cells and reinitiate a
cyclical pattern of infection.
Transgenic Models of Urothelial Transformation. Xue-Ru Wu (New York
University) presented research on the development and characterization of
several transgenic and knockout mouse models of bladder cancer. These
included mice with specific urothelial expression of Ha-ras, epidermal
growth factor, or Simian virus 40 large T antigen. Research Priorities: in
the next few years, the urothelial field will likely see a significant
increase in the utilization of transgenic and knockout approaches to study
gene function and disease pathogenesis. The focus of genes to be targeted
will be shifted from globally acting to pathway-specific ones. Newer models
that allow not only urothelium-specific, but also temporally controlled gene
expression and inactivation need to be developed, so that they more closely
simulate the somatic events in humans. Compound mice harboring multiple
genetic alterations will be extremely useful for elucidating gene synergy
and factors controlling cancer progression. Finally, the mouse models will
serve as invaluable in vivo tools for identifying and validating drug
targets and evaluating chemoprevention strategies.
In vitro models of human urothelium: differentiation and function. Jenny
Southgate (University of York, UK) presented procedures to isolate and
propagate normal human urothelial (NHU) cells. While normal urothelium in
situ is mitotically quiescent and displays stratification into basal,
intermediate and specialized superficial cell zones, monocultures of
urothelial cells are highly proliferative and show little evidence of
differentiation. A critical aim has been to determine whether disruption of
urothelial tissue architecture and/or removal of cells from the in vivo
environment irreversibly compromises the differentiation and functional
potential of urothelial cells. Results suggest that in vitro-propagated NHU
cells show a normal and reversible adaptive response to culture, adopting a
proliferative and migratory “wound-healing” phenotype. Furthermore, the
cells retain the capacity to undergo urothelium-specific differentiation and
to form a functional barrier urothelium. The NHU cell culture system can,
therefore, be used to study normal physiological mechanisms, such as the
regulation of proliferation and cytodifferentiation, and may be adapted to
study pathogenic processes, including interstitial cystitis and cancer. In
conclusion, the NHU cell culture phenotype appears to reflect a ‘normal’
response to an artificial in vitro environment, but the cells remain
responsive to exogenous regulatory factors. This has important implications,
both for the use of in vitro systems as models of normal human urothelial
physiology, function and pathogenesis, and ultimately for using tissue
engineering strategies to restore urinary bladder function.
Genomic approach in bladder cancer biology. Robert E. Hurst (University of
Oklahoma) studied the three-dimensional growth of normal and abnormal
urothelial cells. The contributions of inherent malignancy and the effect of
extracellular matrix on phenotype in culture on gene expression were also
studied by combining modern genomics with bioinformatics. This approach can
be used to make sense of the almost bewildering richness of potential genes
and pathways by identifying key promoter motifs and transcription factors
that may be active in a process. These regulatory motifs are compared to the
correlational clusters with the finding that a significant fraction of genes
whose expression is correlated share one or more regulatory motifs. Research
Priorities: the key problems of the 21st century will revolve around
integration of the huge amount of experimental data and the development of
system-level models that can be used to understand diseases such as cancer,
interstitial cystitis, susceptibility to infection, developmental defects,
regeneration, and the adverse effects of aging processes and trauma. For the
urothelium, learning how urothelial growth and differentiation are regulated
is important to the effective cure or management of interstitial cystitis,
recurrent UTI and incontinence. Building more realistic models of
carcinogenesis and progression that take into account genetic instability
and selection and the interactions between cells and stroma seems important
to controlling bladder cancer.
Genomic and expression alterations in bladder cancer. Dr. Frederic Waldman
(University of California at San Francisco) used Array-based comparative
genomic hybridization (CGH) and cDNA expression arrays to analyze a single
sample set of bladder tumors. A total of 97 tumors were analyzed by CGH, and
80 tumors by expression arrays, including both TCC and SCC histology and all
stages of superficial and muscle-invasive disease. Both unsupervised and
supervised approaches were used to separate tumor subgroups and identify
gene loci. Array CGH showed clear differences among pTa, pT1 and
muscle-invasive tumors. Expression analysis showed a separation of the
tumors into superficial versus muscle-invasive groups using unsupervised
hierarchical clustering and also using Prediction Analysis of Microarrays.
There was excellent correlation between frequent copy number alterations and
expression at the level of the whole genome as well as at individual gene
levels. The combination of the two array technologies has the power to
highlight candidate genes implicated in bladder cancer development and
progression. Genes showing altered copy number and/or expression have the
potential to be developed as biomarkers leading to the development of new
approaches to clinical management of bladder cancer.
Immunohistochemical expression of TRPV1 receptors in normal urothelium. Dr.
Massimo Lazzeri (Ferrara University, Italy) presented results indicating the
presence of TRPV1 on normal human urothelium and showed a progressive loss
of the expression of this receptor as the tumoral stage increased. The value
of this finding remains unknown, and further studies are mandatory in order
to confirm the results and suggest a hypothesis on the role of TRPV1 as a
potential target for chemotherapy or tumoral chemoprevention.
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