Molecular markers for predicting recurrence, progression and outcomes of bladder cancer (do the poster boys need new posters?)

Soluble Expression of Bladder Cancer Biomarker Matrix Metalloproteinase 1

BACKGROUND

Matrix metalloproteinase 1 (MMP1) has been shown as a novel unique biomarker of bladder cancer in urine. MMP1 can only be detected using conventional and time-consuming methods, such as ELISA and Western. Refolded MMP1 has been achieved and used in probe screen for many years, while there is no clinical application for MMP1 detection until now. Soluble expression of MMP1 is necessary in urine detection.

METHODS

cDNA of MMP1 has been isolated from human embryonic kidney 293(HEK293) cells. The catalytic domain of MMP1 is expressed as fusion protein with Escherichia coli thioredoxin (TrxA). The 30 kDa recombinant proteins were purified by Ni-chelating chromatography. The activity of soluble MMP1 was determined and compared with refolded MMP1 by zymography.

RESULTS

Compared with refolded MMP1, TrxA can increase the solubility of MMP1. The soluble MMP1 has the same protein sequences with refolded MMP1 and increased 1.54-fold of gelatin-degradation activities than refolded MMP1.

CONCLUSION

Successfully soluble expression of MMP1 has been achieved by fusion expression and will make progress in discovering specific molecular probes against MMP1.

Prognostic significance of heme oxygenase-1, S100 calcium-binding protein A4, and syndecan-1 expression in primary non-muscle-invasive bladder cancer

We investigated the prognostic significance of heme oxygenase-1 (HO-1), S100 calcium-binding protein A4 (S100A4), and syndecan-1 (SYND1) expression in patients with primary non-muscle-invasive bladder cancer (NMIBC). Immunohistochemical studies were performed on tissue specimens from 109 patients diagnosed with primary NMIBC following complete transurethral resection, with the expression dichotomized as negative/mild ("low") versus moderate/strong ("high") according to scores based on staining area and intensity. The effect of each biomarker on recurrence-free survival (RFS) and progression-free survival (PFS) was analyzed. The predictive accuracy for RFS and PFS in multivariate Cox regression models with or without (the baseline model) biomarkers was estimated using the Harrell concordance index. High HO-1, S100A4, and SYND1 expressions were observed in 33.0%, 36.7%, and 63.3% cases, respectively. High HO-1 and S100A4 expressions were significantly associated with various adverse pathological characteristics (high T stage and grade); SYND1 expression was inversely correlated with these characteristics (all, P < .05). In the baseline multivariate model, multifocality, intravesical therapy, and T stage were significant predictors for RFS, whereas intravesical therapy and T stage had marginal statistical significance in predicting PFS. In the multivariate model with the biomarkers, the 3 biomarkers were significant predictors for RFS; and HO-1 expression was a significant predictor for PFS. Addition of the 3 biomarkers to the baseline model significantly increased the predictive accuracy for RFS from 0.754 to 0.828 (P = .043). Our findings suggest that HO-1, S100A4, and SYND1 expressions have prognostic value in primary NMIBC; thus, their evaluation might be useful for determining treatment strategies.

Noninvasive multianalyte diagnostic assay for monitoring bladder cancer recurrence

Background

The purpose of this study was to establish the clinical performance of a urine-based assay, called a multianalyte diagnostic readout, in monitoring for bladder cancer recurrence.

Methods

This was a prospective, multicenter, single assessment observational study. The multianalyte diagnostic readout uses a combination of one protein and three DNA biomarkers. Urine samples from 733 patients undergoing monitoring for bladder cancer recurrence were analyzed for matrix metalloproteinase-2 levels, the presence of mutant FGFR3 DNA, and hypermethylation of the NID2 and VIM genes. The probability of a patient having (positive predictive value) or not having (negative predictive value) recurrent bladder cancer was determined by FGFR3 alone or all four biomarkers combined, respectively.

Results

Cystoscopy/biopsy diagnosed 63 patients with bladder cancer recurrence at the time of study assessment. The four-biomarker assay identified 237 patients as having a low probability of disease recurrence, 231 of whom were determined by cystoscopy as not having recurrent cancer, resulting in a negative predictive value of 97.5% at 90.5% sensitivity. The FGFR3 assay identified 49 patients with FGFR3 mutations, 19 of whom were confirmed by biopsy as having cancer, resulting in a positive predictive value of 38.8%, with 95.5% specificity.

Conclusion

The urine-based multianalyte diagnostic readout assay was able to delineate the patient population into those highly likely to have bladder cancer recurrence, those unlikely to have recurrent disease, and those with an average risk for bladder cancer recurrence.

A noninvasive multianalyte urine-based diagnostic assay for urothelial cancer of the bladder in the evaluation of hematuria

OBJECTIVE

To test whether a noninvasive urine-based multianalyte diagnostic readout assay that uses protein and DNA biomarkers can risk stratify patients with hematuria into those who are or are not likely to have bladder cancer and those who should receive standard care.

PATIENTS AND METHODS

This prospective, observational, multicenter, single-assessment study was conducted between June 12, 2009, and April 15, 2011. Eligible patients presented with hematuria and as part of their evaluation underwent cystoscopy. Urine samples were analyzed for the presence of mutant FGFR3 and quantified matrix metalloproteinase 2 and the hypermethylation of TWIST1 and NID2. A patient's chance of having (positive predictive value [PPV]) or not having (negative predictive value [NPV]) cancer was determined by FGFR3 alone or by all 4 biomarkers, respectively.

RESULTS

Cystoscopy/biopsy diagnosed 690 of 748 patients as negative and 58 as positive for bladder cancer. Of 21 patients identified by FGFR3 as highly likely to have cancer, 20 were also positive by cystoscopy/biopsy, resulting in a PPV of 95.2% (20 of 21), with specificity of 99.9% (689 of 690). The 4-marker combination identified 395 patients as having a low likelihood of cancer. Of these, 56.2% (388 of 690) also had negative biopsy/cystoscopy findings, resulting in an NPV of 98.2% (388 of 395). In total, 416 of the 748 patients with hematuria (55.6%) were identified with extremely high NPV and PPV to have or not have bladder cancer.

CONCLUSION

This multianalyte assay accurately stratified patients with high confidence into those who likely do or do not have bladder cancer. This test was developed to enhance and not to eliminate referrals for urologic evaluation.

Benzalkonium bromide as a new potential instillation drug for bladder cancer: hypothesis and pilot study

Non-muscle-invasive urothelial carcinoma of the bladder has a high rate of recurrence, necessitating use of a variety of adjuvant treatments. A single, immediate post-operative administration of chemotherapy is an important measure for reducing the rate of recurrences, but the overall effect is not satisfactory and the treatment is a burden to the patient. Hence, there is a need for a new, more effective and cheaper agent for adjuvant treatment of non-muscle-invasive bladder carcinomas.

Although cationic surfactants such as benzalkonium salts are used clinically and hygienically for the control of bacterial growth, there have been reports that cationic surfactants such as benzethonium chloride induce apoptosis in normal and in cancerous cells. We report our experience with benzalkonium bromide (BB) accidentally administered into a patient‘s bladder as saline. It caused severe hematuria and pain, but after a week of persistent administration in the bladder, the patient was cured, as supported by evidence from cystoscopy, indicating that BB destroys bladder mucosa and suggesting that BB maybe a novel agent for use in a single, immediate post-operative administration. We present preliminary data to support this hypothesis and provide discussion we hope will be useful as the foundation for further experiments.

A noninvasive multi-analyte diagnostic assay: combining protein and DNA markers to stratify bladder cancer patients

Purpose

The authors recently reported the development of a noninvasive diagnostic assay using urinary matrix metalloproteinases (MMPs) as monitors of disease-free status and bladder cancer in high-risk populations. Using an approach called clinical intervention determining diagnostic (CIDD), they identified with high confidence those patients who could be excluded from additional intervention. To maximize performance, MMPs were combined with DNA-based markers and CIDD was applied to a population of patients undergoing monitoring for recurrence.

Patients and methods

Urine samples were obtained from 323 patients, 48 of whom had a recurrence and 275 of whom did not have cancer upon cytoscopic evaluation. Twist1 and Nid2 methylation status was determined using methylation-specific polymerase chain reaction, FGFR3 mutational status by quantitative PCR, and MMP levels by enzyme-linked immunosorbent assay.

Results

Using a combination of these DNA and protein markers, the authors identified with high confidence (97% negative predicted value) those patients who do not have cancer. Cutoffs were adjusted such that at 92% sensitivity, 51% of disease-free patients might be triaged from receiving further tests.

Conclusion

The multi-analyte diagnostic readout assay described here is the first to combine protein and DNA biomarkers into one assay for optimal clinical performance. Using this approach, the detection of FGFR3 mutations and Twist1 and Nid2 methylation in the urine of patients undergoing bladder cancer recurrence screening increase the sensitivity and negative predictive value at an established MMP protein cutoff. This noninvasive urinary diagnostic assay could lead to the more efficient triage of patients undergoing recurrence monitoring.

Role of systemic peri-operative chemotherapy in management of transitional cell carcinoma of bladder

Bladder cancer has variable biological behavior pattern in different individuals and the debate regarding peri-operative use of systemic chemotherapy with the surgical management remains. The optimal treatment strategy, regimen and the timing of peri-operative chemotherapy are not yet known. Here we review the existing literature for the use of systemic peri-operative chemotherapy in management of advanced bladder cancer.

Current therapeutic strategies for invasive and metastatic bladder cancer

BACKGROUND

Bladder cancer is one of the most common cancers in Europe, the United States, and Northern African countries. Muscle-invasive bladder cancer is an aggressive epithelial tumor, with a high rate of early systemic dissemination. Superficial, noninvasive bladder cancer can most often be cured; a good proportion of invasive cases can also be cured by a combined modality approach of surgery, chemotherapy, and radiation. Recurrences are common and mostly manifest as metastatic disease. Those with distant metastatic disease can sometime achieve partial or complete remission with combination chemotherapy.

RECENT DEVELOPMENTS

Better understanding of the biology of the disease has led to the incorporation of molecular and genetic features along with factors such as tumor grade, lympho-vascular invasion, and aberrant histology, thereby allowing identification of 'favorable' and 'unfavorable' cancers which helps a more accurate informed and objective selection of patients who would benefit from neoadjuvant and adjuvant chemotherapy. Gene expression profiling has been used to find molecular signature patterns that can potentially be predictive of drug sensitivity and metastasis. Understanding the molecular pathways of invasive bladder cancer has led to clinical investigation of several targeted therapeutics such as anti-angiogenics, mTOR inhibitors, and anti-EGFR agents.

CONCLUSION

With improvements in the understanding of the biology of bladder cancer, clinical trials studying novel and targeted agents alone or in combination with chemotherapy have increased the armamentarium for the treatment of bladder cancer. Although the novel biomarkers and gene expression profiles have been shown to provide important predictive and prognostic information and are anticipated to be incorporated in clinical decision-making, their exact utility and relevance calls for a larger prospective validation.

Biomarkers in bladder cancer

Detailed molecular insights into bladder cancer biology might allow more detailed prognostication and optimization of treatment with the objective of improving patient outcome and quality of life. However, in bladder cancer research the search for biomarkers has been called into question and has even obtained notoriety. It is unlikely that any single marker will be able to improve prognostication for patients with bladder cancer above and beyond grade and stage, but a combination of multiple independent markers might more precisely predict the outcome. From a previous review, we identified seven biomarkers to study within the setting of the Bladder Cancer Prognosis Programme (BCPP), a 5-year multicentre programme of research based at the University of Birmingham and funded by Cancer Research UK, investigating their effectiveness in predicting recurrence and progression. As part of the ongoing quality-assurance process for BCPP we present an updated review of our selected biomarkers, as well as highlighting other recent important developments in bladder cancer research.

DEK proto-oncogene expression interferes with the normal epithelial differentiation program

Overexpression of the DEK gene is associated with multiple human cancers, but its specific roles as a putative oncogene are not well defined. DEK transcription was previously shown to be induced by the high-risk human papillomavirus (HPV) E7 oncogene via E2F and Rb pathways. Transient DEK overexpression was able to inhibit both senescence and apoptosis in cultured cells. In at least the latter case, this mechanism involved the destabilization of p53 and the decreased expression of p53 target genes. We show here that DEK overexpression disrupts the normal differentiation program in a manner that is independent of either p53 or cell death. DEK expression was distinctly repressed upon the differentiation of cultured primary human keratinocytes, and stable DEK overexpression caused epidermal thickening in an organotypic raft model system. The observed hyperplasia involved a delay in keratinocyte differentiation toward a more undifferentiated state, and expansion of the basal cell compartment was due to increased proliferation, but not apoptosis. These phenotypes were accompanied by elevated p63 expression in the absence of p53 destabilization. In further support of bona fide oncogenic DEK activities, we report here up-regulated DEK protein levels in both human papilloma virus-positive hyperplastic murine skin and a subset of human squamous cell carcinomas. We suggest that DEK up-regulation may contribute to carcinoma development at least in part through increased proliferation and retardation of differentiation.

Molecular profiling of ADAM12 in human bladder cancer

PURPOSE

We have previously found ADAM12, a disintegrin and metalloprotease, to be an interesting biomarker for breast cancer. The purpose of this study was to determine the gene and protein expression profiles of ADAM12 in different grades and stages of bladder cancer.

EXPERIMENTAL DESIGN

ADAM12 gene expression was evaluated in tumors from 96 patients with bladder cancer using a customized Affymetrix GeneChip. Gene expression in bladder cancer was validated using reverse transcription-PCR, quantitative PCR, and in situ hybridization. Protein expression was evaluated by immunohistochemical staining on tissue arrays of bladder cancers. The presence and relative amount of ADAM12 in the urine of cancer patients were determined by Western blotting and densitometric measurements, respectively.

RESULTS

ADAM12 mRNA expression was significantly up-regulated in bladder cancer, as determined by microarray analysis, and the level of ADAM12 mRNA correlated with disease stage. Reverse transcription-PCR, quantitative PCR, and in situ hybridization validated the gene expression results. Using immunohistochemistry, we found ADAM12 protein expression correlated with tumor stage and grade. Finally, ADAM12 could be detected in the urine by Western blotting; ADAM12 was present in higher levels in the urine from patients with bladder cancer compared with urine from healthy individuals. Significantly, following removal of tumor by surgery, in most bladder cancer cases examined, the level of ADAM12 in the urine decreased and, upon recurrence of tumor, increased.

CONCLUSIONS

ADAM12 is a promising biomarker of bladder cancer.

Molecular biomarkers for cancer detection in blood and bodily fluids

Cancer is a major and increasing public health problem worldwide. Traditionally, the diagnosis and staging of cancer, as well as the evaluation of response to therapy have been primarily based on morphology, with relatively few cancer biomarkers currently in use. Conventional biomarker studies have been focused on single genes or discrete pathways, but this approach has had limited success because of the complex and heterogeneous nature of many cancers. The completion of the human genome project and the development of new technologies have greatly facilitated the identification of biomarkers for assessment of cancer risk, early detection of primary cancers, monitoring cancer treatment, and detection of recurrence. This article reviews the various approaches used for development of such markers and describes markers of potential clinical interest in major types of cancer. Finally, we discuss the reasons why so few cancer biomarkers are currently available for clinical use.

The pharmacogenetic impact of inflammatory genes on bladder cancer recurrence

Although superficial bladder cancer can generally be treated successfully, tumor recurrence is a serious clinical problem, with a recurrence rate of approximately 70%. Clinicopathologic markers for superficial bladder cancer recurrence remain the best prognostic predictors in clinical decision making. Biomarkers that may complement clinicopathological parameters and increase the accuracy of outcome prediction have been extensively studied. A large number of molecular markers, including inflammatory genes, have been suggested to have predictive value for bladder cancer recurrence. The role of inflammation in the development and progression of bladder cancer, as in other malignancies, is gaining increased recognition. This review will summarize recent data regarding the impact of genetic variations in inflammatory genes on de novo bladder cancer recurrence, as well as recurrence in the context of bacillus Calmette-Guerin (BCG) treatment. Genomic variation as a mechanism that may modify BCG efficacy is discussed in detail.

Molecular characterization of early-stage bladder carcinomas by expression profiles, FGFR3 mutation status, and loss of 9q

We used gene expression profiling, mutation analyses of FGFR3 and TP53, and LOH analyses of chromosome 9 and the TP53 region on chromosome arm 17p, to molecularly characterize 75 Ta and T1 bladder carcinomas. We identified four major cellular processes related to cell cycle, protein synthesis, immune response, and extra cellular components that contribute to the expressional heterogeneity of early-stage urothelial cell carcinoma (UCC). Activating FGFR3 mutations were found at the highest frequency in G1 tumors (80%), and showed a strong correlation with FGFR3 expression. In contrast, G3 tumors displayed mutations in less than 10% of the cases and a low level of FGFR3 expression. Even though LOH on chromosome 9 was not associated with any specific expression pattern, our data indicate that loss of chromosome 9 is associated with tumor development rather than initiation. The combined analyses suggest the existence of two types of UCC tumors, one which is characterized by FGFR3 mutation or expression, high expression of protein synthesis genes, and low expression of cell cycle genes. Furthermore, the presented data underscore FGFR3 receptor involvement in urothelial cell transformation as the presence of FGFR3 mutations has a major impact on the global gene expression profile of bladder carcinomas.

Cancer Specific Outcomes in Patients With PT0 Disease Following Radical Cystectomy

PURPOSE

We assessed clinical outcomes in patients found to have no evidence of disease, ie pT0, in the cystectomy specimen following radical cystectomy for transitional cell carcinoma.

MATERIALS AND METHODS

Between 1984 and 2003, 955 consecutive patients underwent bilateral pelvic lymphadenectomy and radical cystectomy for bladder cancer at 3 institutions, namely The Johns Hopkins Hospital, University of Texas Southwestern Medical Center and Baylor College of Medicine. Excluding nonTCC histology and patients with missing data resulted in 888 evaluable cases. Primary end points were recurrence-free survival and bladder cancer specific survival.

RESULTS

Final pathological evaluation revealed absent transitional cell carcinoma in the cystectomy specimen, ie pT0, in 59 patients (7%), of whom 2 (3%) had pathologically positive lymph nodes. Transurethral resection stage or clinical stage data were available on 56 patients (95%), including Tis in 5 (9%), Ta in 2 (4%), T1 in 18 (32%), T2 in 29 (52%) and T3 in 2 (4%). Overall 6 recurrences (10%) were noted, including cTis in 1 case, cT1 in 1, cT2 in 3 and cT3 in 1. Median followup in patients with pT0 disease was 56 months (range 3 to 183). Three patients (5%) died of bladder cancer and another 4 (7%) died of other causes. Five and 10-year bladder cancer progression-free and cancer specific survival estimates in patients with pT0 disease were 90% and 81%, and 95% and 85%, respectively.

CONCLUSIONS

Despite excellent clinical outcomes in the majority of patients with no evidence of tumor on final pathological evaluation not all patients with pT0 disease in the cystectomy specimen are cured of bladder cancer. These events may even occur in patients with nonmuscle invasive or muscle invasive organ confined pathology at staging transurethral resection. Further study is needed to identify prognostic factors in this population.

Discovery and validation of new protein biomarkers for urothelial cancer: a prospective analysis

BACKGROUND

Non-invasive methods for diagnosis of urothelial carcinoma have reduced specificity in patients with non-malignant genitourinary disease or other disorders. We aimed to use mass spectrometry and bioinformatics to define and validate a cancer-specific proteomic pattern.

METHODS

We used capillary-electrophoresis-coupled mass spectrometry to obtain polypeptide patterns from urine samples of 46 patients with urothelial carcinoma and 33 healthy volunteers. From signatures of polypeptide mass, we established a model for predicting the presence of cancer. The model was refined further by use of 366 urine samples obtained from other healthy volunteers and patients with malignant and non-malignant genitourinary disease. We estimated the proportion of correct classifications from the refined model by applying it to a masked group containing 31 patients with urothelial carcinoma, 11 healthy individuals, and 138 patients with non-malignant genitourinary disease. We also sequenced several diagnostic polypeptides for urothelial carcinoma.

FINDINGS

We identified a diagnostic urothelial-carcinoma pattern of 22 polypeptide masses. On masked assessment, prediction models based on these polypeptides correctly classified all samples of urothelial carcinoma (sensitivity 100% [95% CI 87-100) and all healthy samples (specificity 100% [84-100]). Correct identification of patients with urothelial carcinoma from those with other malignant and non-malignant genitourinary disease ranged from 86% to 100%. A prominent polypeptide from the diagnostic pattern for urothelial carcinoma was identified as fibrinopeptide A-a known biomarker of ovarian cancer and gastric cancer.

INTERPRETATION

Validation of a highly specific biomarker pattern for urothelial carcinoma in a large group of patients with various urological disorders could be used in the diagnosis of other diseases that are identified in urine samples or in other body fluids.

FGFR3 and p53 protein expressions in patients with pTa and pT1 urothelial bladder cancer

AIMS

This study is designed to evaluate the expression and prognostic value of FGFR3 protein expression in patients with pTa/pT1 tumours and to determine the significance of the combinations of FGFR3 and p53 protein expressions in bladder pathogenesis.

MATERIALS AND METHODS

A tissue microarray (TMA) of 107 pTa, and 147 pT1 tumours was constructed. The TMA sections were immunostained with FGFR3 and p53 monoclonal antibodies.

RESULTS

There were significant associations between loss of FGFR3 and tumour stage (p<0.001) and grade (p<0.001) and between p53 overexpression and tumour stage and grade (p<0.001 and p<0.001, respectively). There was no association between FGFR3 and p53 proteins (p=0.107). In addition, tumours with FGFR3+/p53- phenotype have slower recurrence rate than other (FGFR3+/p53+, FGFR3-/p53- and FGFR3-/p53+).

CONCLUSION

1-FGFR3 expression is significantly associated with two important prognostic factors; stage and grade. 2-FGFR3 protein expression is not an independent predictive factor for pTa/pT1 tumour recurrence and progression. 3-Tumours with FGFR3+/p53- phenotype seem to have a distinctive pathway in bladder tumorigenesis.

Neoadjuvant Chemotherapy in Transitional-cell Carcinoma of the Bladder

Neoadjuvant chemotherapy in transitional-cell carcinoma of the bladder (TCC) improves survival. This is one of the most important developments in the management of muscle-invasive bladder cancer in recent times. There is an improved absolute 5-year survival of at least 5% for T2-T4 disease. To achieve this benefit, a cisplatin-containing combination is required. There is no difference in survival whether radical radiotherapy or radical cystectomy is given as subsequent definitive treatment.

From proteomics to biomarker discovery in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly. AD is an invariably fatal neurodegenerative disorder with no effective treatment or definitive antemortem diagnostic test. Little is known about the changes in the brain preceding or accompanying initiation of the disease. Understanding the biological processes, which occur during AD onset and/or progression, will improve the diagnosis and treatment of the disease. As we will discuss in this review article, using high-throughput cDNA microarray we identified candidate genes whose expression is altered in the brain of cases at risk for AD dementia. However, it is possible that the use of the cDNA microarray technology alone may underestimate post-transcriptional modifications and therefore provides only a partial view of the biological problem of interest. As such, the combination of cDNA and protein arrays may provide a more global picture of the biological processes being studied. Based on this hypothesis, we initiated a series of high-throughput proteomic studies and found that the expressions of proteins involved in synaptic plasticity are selectively altered in the brain of cases at high risk to develop AD dementia (mild cognitive impairment; MCI). This is consistent with our cDNA microarray evidence showing that the expression of a-type synapsins is selectively altered in the brain of MCI cases. Collectively, these studies support the feasibility and usefulness of high-throughput cDNA microarray and proteomics techniques to study the sequential changes of distinctive gene expression patterns in the brain as a function of the progression of AD dementia.

Loss of expression of the adipocyte-type fatty acid-binding protein (A-FABP) is associated with progression of human urothelial carcinomas

Bladder cancer is the fifth most common malignancy in the world and represents the second most common cause of death among genitourinary tumors. Current prognostic parameters such as grade and stage cannot predict with certainty the long-term outcome of bladder cancer, and as a result there is a pressing need to identify markers that may predict tumor behavior. Earlier we identified the adipocyte fatty acid-binding protein (A-FABP), a small-molecular-mass fatty acid-binding protein that functions by facilitating the intracellular diffusion of fatty acids between cellular compartments as a putative marker of progression based on a limited study of fresh bladder urothelial carcinomas (UCs) (Celis, J. E., Ostergaard, M., Basse, B., Celis, A., Lauridsen, J. B., Ratz, G. P., Andersen, I., Hein, B., Wolf, H., Orntoft, T. F., and Rasmussen, H. H. (1996) Loss of adipocyte-type fatty acid binding protein and other protein biomarkers is associated with progression of human bladder transitional cell carcinomas. Cancer Res.56, 4782-4790). Here we have comprehensively examined the protein expression profiles of a much larger sample set consisting of 153 bladder specimens (46 nonmalignant biopsies, 11 pTa G1, 40 pTa G2, 10 pTa G3, 13 pT1 G3, 23 pT2-4 G3, and 10 pT2-4 G4) by gel-based proteomics in combination with immunohistochemistry (IHC) using a peptide-based rabbit polyclonal antibody that reacts specifically with this protein. Proteomic profiling showed a striking down-regulation of A-FABP in invasive lesions, a fact that correlated well with immunohistochemical analysis of the same samples. The IHC results were confirmed by using a tissue microarray (TMA) containing 2,317 samples derived from 1,849 bladder cancer patients. Moreover, we found that the altered expression of A-FABP in invasive UCs is not due to deregulated expression of peroxisome proliferator-activated receptor gamma (PPARgamma), a trans-activator of A-FABP. Taken together, these results provide evidence that deregulation of A-FABP may play a role in bladder cancer progression and suggest that A-FABP could have a significant prognostic value in combination with other biomarkers.