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Keywords:

  • upper urinary tumours;
  • prognostic factors;
  • molecular characterization;
  • bladder cancer

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

OBJECTIVES

To assess gene-expression patterns of BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, TP53, AGR2, HER2 and VEGF, widely known markers of bladder urothelial carcinoma (UC) in upper tract UC, and to determine their value as prognostic factors of tumour progression and cancer-specific survival.

PATIENTS AND METHODS

The study included 83 formalin-fixed paraffin-embedded tissue specimens (68 and 15 from patients with UTUC and controls, respectively) collected between 1990 and 2004. Thirteen bladder cancer-related genes were selected from previous reports and analysed by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) in all samples.

RESULTS

Six genes were over-expressed (BIRC5, FGFR3, KRT20, UPK2, FXYD3 and hTERT) and three under-expressed (AGR2, TP53 and VEGF) in the tumour group (P < 0.05). For four genes (IGF2, EBF1, CDH1 and HER2) there was no statistically significant difference between the tumour and control groups. Overall, 21 patients developed tumour progression and 13 died from UTUC after a mean follow-up of 35.24 months. The 5-year disease-free progression and cancer-specific survival rates were 65.8% and 72.9%, respectively. In a multivariate regression analysis, the independent predictive variable for tumour progression and cancer-specific survival was pathological stage (hazard ratio 3.60, P < 0.001; and 3.73, P < 0.005, respectively), but none of the studied genes were identified as prognostic factors of tumour progression or cancer-specific survival.

CONCLUSIONS

Our data suggest that bladder cancer and UTUC share some characteristics, but have differences in gene expression. None of BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, TP53, AGR2, HER2 and VEGF were correlated either tumour progression or survival.


Abbreviations
UT

upper urinary tract

UC

urothelial carcinoma

PFS

progression-free survival

CSS

cancer-specific survival

NU

nephroureterectomy

qRT-PCR

quantitative reverse transcription-PCR

TPAMMK

TaqMan Pre-amplification Master Mix Kit

HR

hazard ratio.

INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

Upper urinary tract urothelial carcinoma (UTUC) is an infrequent tumour, with an annual incidence of 0.7–1.1 per 100 000 inhabitants in Europe, that has increased slightly over the last 30 years. It represents 8% of all patients with urothelial cancers. Of UTUCs, 80% are detected after a diagnosis of bladder cancer; two-thirds of these patients will develop other urothelial tumours in the future [1]. Radical surgery, e.g. nephroureterectomy (NU), is the accepted treatment for localized UTUC. Pathological stage and tumour grade are the only established prognostic factors associated with tumour progression and survival, but they are insufficient to predict the individual outcome of these tumours [2]. More accurate knowledge of the biological behaviour of tumours would allow tailored treatment schedules to be offered to patients, in an attempt to increase survival and decrease morbidity.

Genetic abnormalities occur in the initial stages of tumour development and they are the primary determinants of neoplastic transformation. Detecting such genetic aberrations can assist in detecting early tumours, surveillance of patients with cancer, and risk assessment of tumour progression and outcome of the tumour [3]. Several keys molecules and pathways that regulate critical cellular processes have been identified as important in the course of urothelial tumorigenesis and progression. These processes that can respond to external carcinogenic cues or become internally dysregulated due to genetic alterations, e.g. cell-cycle regulation, cell death, cell growth, signal transduction, and gene regulation. Also important are two ‘extrinsic’ processes that contribute to tumour maintenance and progression by interacting with stromal elements and adjoining cells, i.e. angiogenesis and tumour cell invasion [4].

In bladder cancer, several studies have reported genomic profiles to improve knowledge about diagnosis, prognosis and therapeutic targets. Most of these reports describe diagnostic tests to identify molecular alterations in tumour cells exfoliated in the urine [5,6]. Survivin or BIRC5 is an anti-apoptotic protein, a member of the inhibitor-of-apoptosis family [7]. Higher survivin levels are associated with a higher risk of bladder cancer and higher-grade tumours [8]. A recent report using quantitative reverse transcription-PCR (qRT-PCR) showed that overexpression of BIRC5 in bladder tumour correlated with a poor prognosis [9]. IGF2 is thought to be involved in growth regulation and has already been shown to be overexpressed in some UCs [10]. Oya et al.[10] reported no correlation of altered IGF2 expression with tumour stage or grade, using qRT-PCR in tumour tissue and cell lines. AGR2 and FXYD3 have been related to bladder cancer dissemination, using qRT-PCR [11]. KRT20 and UPK2 are widely known conventional markers for epithelial cells and have already been considered as markers for bladder tumour dissemination and other different types of cancer [12,13]. KRT20 is also used in urine samples as a diagnostic tool for bladder cancer by RT-PCR [14]. HTERT might be important in the tumorigenic process; its activation is known to immortalize cells in many cancers [15]. In bladder cancer, HTERT correlated with the progression of stage and grade, using RT-PCR [16]. FGFR3, HER2 and VEGF are involved in cell growth and carcinogenic processes, and they are related to increase recurrence, decreased survival and higher stage, invasion and nodal metastasis, respectively, in bladder cancer [4]. P53 is involved in cell-cycle regulation and it is related to increased recurrence, decreased survival and amenability to cisplatin chemotherapy [4]. EBF1 and CDH1 are included in a DNA microarray expression profiling of bladder cancer using qRT-PCR in urine samples [17].

The molecular technique of qRT-PCR has been used in various solid tumours to determine differential gene expression of tumour samples compared with healthy tissues. Until recently, qRT-PCR was used only to analyse fresh-frozen tissue samples, which yield a high quality and quantity of RNA. However, the recent use of this technique to analyse formalin-fixed, paraffin-embedded samples has greatly facilitated retrospective studies in which correlations with surveillance and molecular data are possible. In addition, a novel system has been described, the TaqMan Pre-amplification Master Mix Kit (TPAMMK; Applied Biosystems Inc., Foster City, CA, USA), to increase cDNA quantity before gene-expression analysis by conventional qPCR [18,19]. This system allows a measurement of gene expression in formalin-fixed, paraffin-embedded samples that yield scarce quantities of RNA.

In the present study we tested a group of genes (BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, AGR2, TP53, HER2 and VEGF) related to bladder cancer to correlate their expression with tumour progression-free survival (PFS) and cancer-specific survival (CSS).

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

We conducted a retrospective study in which 86 patients (mean age 69.42 years, range 49.4–101.4) with UTUC and who underwent NU between 1990 and 2004 were included. The only exclusion criterion was lack of tissue from the archived blocks. Fifteen normal UTs were also collected as controls (mean age 42.6 years, range 35.2–69.7; eight women and seven men). This control group also had NU for living donor transplantation; the characteristics of the study population are shown in Table 1.

Table 1.  Characteristics of studied population
Stage/gradeN patientsTumour location, n
PelvisUreter
Stage (TNM)
 Ta 9 63
 T117 98
 T210 73
 T321165
 T4 11 83
Grade (WHO)
 I 4 31
 II32248
 III32266

The median (range) follow-up was 37.2  (0.3–182.7) months; patients were followed at 3-month intervals for the first year, 6-month intervals for the next 2 years, and if they were disease-free after 3 years, were assessed annually. Abdominal and pelvic CT, cytology and cystoscopy were used to assess the patients. The disease was considered to be progressing when distant metastasis or pathological nodes developed during the follow-up.

Tumours were graded and classified according to the WHOs [20] and TNM systems of the International Union Against Cancer [21]. Samples were obtained under an institutional review board-approved protocol. The tissue was fixed in 10% formalin within 24 h and embedded in paraffin. Each specimen was stained with haematoxylin and eosin to determine the presence of tumour cells. These stained sections were reviewed and a representative tumour area was selected for each block. Four sections of each tissue paraffin block was cut at 20-µm thick and used for RNA isolation. Total RNA was isolated from specimens using the RecoverAll Total Nucleic Acid Isolation Kit (Ambion Inc., Applied Biosystems) according to the manufacturer’s protocol. Total RNA was quantified with a spectrophotometer (NanoDrop Technologies, Wilmington, DE, USA).

RNA RT and cDNA pre-amplification cDNA were synthesized from 1 µg of total RNA with the use of the High-Capacity cDNA Archive kit (Applied Biosystems) according to the manufacturer’s instructions. A multiplex PCR pre-amplification of the BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, AGR2, TP53, HER2 and VEGF specific cDNA targets and the endogenous control PPIA was performed using TPAMMK following the manufacturer’s instructions, except that the final volume of the reaction was 10 µL. Briefly, the BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, AGR2, TP53, HER2 and VEGF TaqMan Gene Expression Assays were pooled together at 0.2 × final concentration. Subsequently, 2.5 µL of the pooled assay mix (0.2×) were combined with 100 ng of each cDNA sample and 5 µL of the TPAMM (2×) in a final volume of 10 µL. Thermal cycling conditions were an initial hold at 95 °C for 10 min, 14 pre-amplification cycles of 15 s at 95 °C, and 4 min at 60 °C.

For the amplification reactions we used TaqMan Gene Expression Assays (Applied Biosystems) according to the manufacturer’s instructions, except that the final volume was 20 µL. The reaction mix components for each case were 10 µL TaqMan Universal PCR Master Mix (2×), 1 µL of TaqMan assay and 7 µL of RNase-free water. The reactions, carried out with 2 µL of total RNA, were performed with a real-time PCR system (7500/7500 Fast, Applied Biosystems) by 40 cycles of denaturation, annealing and extension (30 s at 60 °C, 10 min at 95 °C, 15 s at 92 °C and 1.30 min at 60 °C). During the amplification process, the fluorescent intensities of the reporter dye (FAM) were recorded. These data allowed a calculation of the normalized reporter signals that are linked to the amount of product amplified.

The cyclophilin A gene (PPIA) was used as an endogenous control. All samples were analysed in duplicate and the cycle threshold (Ct) mean was obtained for further calculations. Those samples with a PPIA Ct mean of >27 were considered of low RNA quality and were excluded from the analysis. Each experiment included a negative non-template control and an inter-experiment control. The relative expression level of the marker genes for each sample (ΔCt) was described as the difference between the mean Ct from the target gene and the mean Ct from PPIA. Those samples with a Ct of ≤40 were excluded from the analyses. We constructed heat-maps to show gene expression by groups (case-control).

The Mann–Whitney test was used to compare gene expression values between control and tumour samples. The probabilities of PFS and CSS were calculated using Kaplan-Meier curves, with statistical differences assessed by the log-rank test. Hazard ratios (HRs) and 95% CIs were calculated. The Spearman test was used for correlations. The multivariate analysis was by forward stepwise Cox regression. In all tests, P < 0.05 was taken to indicate statistical significance, and accordingly 95% CI for the HRs are presented.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

Thirteen genes related to bladder cancer were evaluated by qRT-PCR in 68 UTUC samples and 15 controls. Six genes were over-expressed (BIRC5, FGFR3, KRT20, UPK2, FXYD3 and hTERT) and three under-expressed (AGR2, TP53 and VEGF) in the tumour group (P < 0.05). For four genes (IGF2, EBF1, CDH1 and HER2) there were no statistically significant differences between tumour and control groups (Fig. 1). Figure 2 shows differential gene expression values according for each of the groups; the gene subcluster over-expressed in control group is clearly apparent (HER2, VEGFA, TP53, FXYD3 and HTERT).

image

Figure 1. Box plots of overexpressed (A) and underexpressed (B) genes in patients with UTUC. Positive and negative values indicate over- and under-expression of UTUC compared with controls. *Significant statistical differences in expression.

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image

Figure 2. A heat map representing unsupervised hierarchical clustering of genes. Samples are grouped as control and tumour; rows, individual genes; columns, samples. High expression levels are in red and low expression levels in green.

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Histological grade correlated with KRT20 and UPK2 overexpression (R = −0.272, P = 0.036, and R = −0.248, P = 0.05, respectively). Pathological stage correlated with KRT20 and FXYD3 overexpression (R = −0.345, P = 0.007, and R = −0.412, P = 0.001, respectively).

Overall 21 patients developed tumour progression after a mean (range) follow-up of 35.24 (0.3–182.7) months. Nine patients had positive lymph nodes at diagnosis. They received adjuvant treatment (platinum-based regimen), but all of them developed tumour progression during the follow-up. The 5-year disease-free progression of the series was 65.8%.

Results from univariate analysis showed that pathological stage was a prognostic factor of tumour progression (HR 3.9, P < 0.05), but none of the studied genes were prognostic. The estimated 5-year tumour PFS rate by pathological stage was 100%, 95%, 80%, 51% and 29% for pTa, pT1, pT2, pT3 and pT4, respectively (Fig. 3A). In the multivariate regression analysis, the only independent predictive variable for tumour progression was pathological stage (HR 3.6, P < 0.001).

image

Figure 3. Kaplan-Meier analysis of tumour PFS (A) and CSS (B) by pathological stage.

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Overall 13 patients died from UTUC during the surveillance period; the 5-year CSS of the series was 72.9%. Pathological stage was the only factor indicative of CSS in the univariate analysis (HR 4.27, P = 0.002). Among genetic markers, a comparison of the 5-year CSS showed no statistically significant differences. The 5-year CSS was 100%, 95%, 89%, 52% and 18% for pTa, pT1, pT2, pT3 and pT4, respectively (Fig. 3B). In the multivariate regression analysis, the only independent predictive variable for CSS was pathological stage (HR 3.73, P < 0.005).

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

UTUC is considered to have a worse prognosis than urothelial bladder cancer. In the present series, more than a quarter of the patients developed tumour progression after 4 years of follow-up. As pathological stage and histological grade are the only established prognostic factors for UTUC, this study focused on the search for molecular markers to improve and individualize the prognosis and disease status.

Gene-expression profiling has been used for the molecular classification of several cancers, including breast, prostate, colon, nonsmall cell lung, lung adenocarcinoma, medulloblastoma and melanoma, as well as lymphoma [22]. This classification has been shown to correlate with clinical phenotype as defined by tumour progression and survival.

Both bladder cancer and UTUC share similar carcinogenic mechanisms, reflecting a common pathology. Patients with UTUC have a 30–40% risk of developing bladder cancer after NU, while patients with primary bladder cancer have only a 0.5–2% risk of subsequent UT tumours [23]. This was the main reason for assessing the 13 genes widely known as markers of bladder UC in patients with UTUC.

There are only a few published reports of the expression of these genes in UTUC. Nakanishi et al.[24] showed, in 125 cases of UTUC, no relationship between HTERT and clinicopathological findings, using in situ hybridization. Jeong et al.[25] reported, from 112 patients, that BIRC5 expression assessed by immunohistochemistry was a poor prognostic factor for survival in patients with UTUC. They found no correlation between P53 and survival. Langner et al.[26], using immunohistochemistry and in situ hybridization in 53 cases, found that HER2 overexpression and HER2 gene amplification were infrequent in their series, and did not correlate with survival. Most of these 13 genes were overexpressed in bladder cancer and constituted prognostic factors for disease progression and survival, but not in UTUC. Although both UTUC and bladder tumours derive from urothelial tissue, there are biological and behavioural variations between them [27].

To our knowledge, the prognostic significance of this set of genes in UTUC, assessed using qRT-PCR in tissue samples, has not reported previously. Genes involved in the behaviour, diagnosis and prognosis of bladder cancer were the starting point for our study. It is necessary to continue searching for new markers to understand the nature and development of these tumours.

In conclusion, our data suggest that bladder cancer and UTUC share some characteristics, but have differences in gene expression. None of BIRC5, FGFR3, IGF2, KRT20, UPK2, EBF1, CDH1, FXYD3, HTERT, TP53, AGR2, HER2 and VEGF were correlated with either tumour progression or survival.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment
  • 1
    Munoz JJ, Ellison LM. Upper tract urothelial neoplasms: incidence and survival during the last 2 decades. J Urol 2000; 164: 15235
  • 2
    Huben RP, Mounzer AM, Murphy GP. Tumor grade and stage as prognostic variables in upper tract urothelial tumors. Cancer 1988; 62: 201620
  • 3
    Marin-Aguilera M, Mengual L, Ribal MJ et al. Utility of fluorescence in situ hybridization as a non-invasive technique in the diagnosis of upper urinary tract urothelial carcinoma. Eur Urol 2007; 51: 40915
  • 4
    Mitra AP, Cote RJ. Molecular pathogenesis and diagnostics of bladder cancer. Annu Rev Pathol 2009; 4: 25185
  • 5
    Sozen S, Biri H, Sinik Z, Kupeli B, Alkibay T, Bozkirli I. Comparison of the nuclear matrix protein 22 with voided urine cytology and BTA stat test in the diagnosis of transitional cell carcinoma of the bladder. Eur Urol 1999; 36: 2259
  • 6
    Lokeshwar VB, Habuchi T, Grossman HB et al. Bladder tumor markers beyond cytology. International Consensus Panel on bladder tumor markers. Urology 2005; 66: 3563
  • 7
    Sharp JD, Hausladen DA, Maher MG, Wheeler MA, Altieri DC, Weiss RM. Bladder cancer detection with urinary survivin, an inhibitor of apoptosis. Front Biosci 2002; 7: e3641
  • 8
    Shariat SF, Casella R, Khoddami SM et al. Urine detection of survivin is a sensitive marker for the noninvasive diagnosis of bladder cancer. J Urol 2004; 171: 62630
  • 9
    Nouraee N, Mowla SJ, Ozhand A, Parvin M, Ziaee SA, Hatefi N. Expression of survivin and its spliced variants in bladder tumors as a potential prognostic marker. Urol J 2009; 6: 1018
  • 10
    Oya M, Schulz WA. Decreased expression of p57 (KIP2) mRNA in human bladder cancer. Br J Cancer 2000; 83: 62631
  • 11
    Marin-Aguilera M, Mengual L, Burset M et al. Molecular lymph node staging in bladder urothelial carcinoma: impact on survival. Eur Urol 2008; 54: 136372
  • 12
    Kurahashi T, Hara I, Oka N, Kamidono S, Eto H, Miyake H. Detection of micrometastases in pelvic lymph nodes in patients undergoing radical cystectomy for locally invasive bladder cancer by real-time reverse transcriptase-PCR for cytokeratin 19 and uroplakin II. Clin Cancer Res 2005; 11: 37737
  • 13
    Ismail MS, Wynendaele W, Aerts JL et al. Detection of micrometastatic disease and monitoring of perioperative tumor cell dissemination in primary operable breast cancer patients using real-time quantitative reverse transcription-PCR. Clin Cancer Res 2004; 10: 196210
  • 14
    Guo B, Luo C, Xun C, Xie J, Wu X, Pu J. Quantitative detection of cytokeratin 20 mRNA in urine samples as diagnostic tools for bladder cancer by real-time PCR. Exp Oncol 2009; 31: 437
  • 15
    Kim NW, Piatyszek MA, Prowse KR et al. Specific association of human telomerase activity with immortal cells and cancer. Science 1994; 266: 20115
  • 16
    Takihana Y, Tsuchida T, Fukasawa M, Araki I, Tanabe N, Takeda M. Real- time quantitative analysis for human telomerase reverse transcriptase mRNA and human telomerase RNA component mRNA expressions as markers for clinicopathologic parameters in urinary bladder cancer. Int J Urol 2006; 13: 4018
  • 17
    Mengual L, Burset M, Ars E et al. DNA microarray expression profiling of bladder cancer allows identification of noninvasive diagnostic markers. J Urol 2009; 182: 7418
  • 18
    Barrachina M, Moreno J, Juves S, Moreno D, Olive M, Ferrer I. Target genes of neuron-restrictive silencer factor are abnormally up-regulated in human myotilinopathy. Am J Pathol 2007; 171: 131223
  • 19
    Denning KM, Smyth PC, Cahill SF et al. A molecular expression signature distinguishing follicular lesions in thyroid carcinoma using preamplification RT-PCR in archival samples. Mod Pathol 2007; 20: 1095102
  • 20
    Mostofi Sorbin LH, Torloni H. Histological Typing of Urinary Bladder Tumors. International Histological Classification of Tumors, No. 10. Geneva: World Health Organization, 1973
  • 21
    Sobin LH, Wittekind Ch. TNM Classification of Malignant Tumours. New York: Wiley, 2002
  • 22
    Modlich O, Prisack HB, Pitschke G et al. Identifying superficial, muscle-invasive, and metastasizing transitional cell carcinoma of the bladder: use of cDNA array analysis of gene expression profiles. Clin Cancer Res 2004; 10: 341021
  • 23
    Habuchi T. Origin of multifocal carcinomas of the bladder and upper urinary tract: molecular analysis and clinical implications. Int J Urol 2005; 12: 70916
  • 24
    Nakanishi K, Hiroi S, Kawai T et al. Expression of telomerase catalytic subunit (hTERT) mRNA does not predict survival in patients with transitional cell carcinoma of the upper urinary tract. Mod Pathol 2001; 14: 10738
  • 25
    Jeong IG, Kim SH, Jeon HG et al. Prognostic value of apoptosis-related markers in urothelial cancer of the upper urinary tract. Hum Pathol 2009; 40: 66877
  • 26
    Langner C, Gross C, Rehak P, Ratschek M, Ruschoff J, Zigeuner R. HER2 protein overexpression and gene amplification in upper urinary tract transitional cell carcinoma: systematic analysis applying tissue microarray technique. Urology 2005; 65: 17680
  • 27
    Phé V, Cussenot O, Rouprêt M. Interest of methylated genes as biomarkers in urothelial cell carcinomas of the urinary tract. BJU Int 2009; 104: 896901

Editorial comment

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES
  9. Editorial comment

This is a retrospective study involving 68 UTUC and 15 control tissues in which the expression level of 13 genes related to UC of the bladder was assessed using real-time qRT-PCR. Genes selected for analysis in this study had been identified as differentially expressed in bladder UC and were evaluated in UTUC as potential biomarkers of prognostic significance. There are no specific grouping of genes selected for study either with respect to the compartmentalization of proteins or function.

The results show that none of the genes studied were correlated with tumour progression or survival, denoting a distinction between the neoplastic pathways underlying UTUC and bladder UC, although genes probably with a primary role in urothelial tumorigenesis had a significantly different expression from control tissue. Despite the uncommon occurrence of UTUC these patients present a clinical challenge, as UTUC has a significantly poorer prognosis than that recorded in bladder UC, where 34% had tumour progression after a 5-year follow-up in this study. Such a scenario justifies a further search for biomarkers of progression in UTUC that should be driven from the expression profile studies in UTUC, executed in a high-throughput microarray format (e.g. mRNA, microRNA, protein) rather than an extrapolation of events from comparative tumours. In this way analytical data are derived directly from the tissue of interest, and investigations would provide insights into the tumorigenic mechanism and clinical behaviour of UTUC. It is likely that in this small patient group such an approach will help to identify a subgroup of UTUC at risk of progression, enabling a more aggressive clinical course of treatment in these patients. Such information will also distinguish differential expression profiles between UTUC and the better characterized counterparts in bladder UC, with the possibility of identifying new therapeutic targets for UTUC. Although this work provides no new clinically useful biomarkers for UTUC it highlights a patient population at risk of progression, and describes an initial foray into the analysis of events underlying tumorigenesis, with the possibility of aiding clinical decision-making in the future.

Ian Summerhayes

Lahey Clinic Medical Center – Cell & Molecular Biology, Burlington, MA, USA