Urinary protein profiles in patients with urothelial bladder tumours

Differential regulation of urine proteins in urothelial neoplasm

Urothelial neoplasm of the urinary bladder has a high rate of multifocality and recurrence. To understand this we first need to understand the changes in the molecular level that distinguishes a normal individual from a patient and also a low grade neoplasm from a high grade. In this work we aim to study the urine proteome of Indian patients with urothelial neoplasm categorised on the basis of their p53 immunohistochemistry. The urine samples of pre-operative patients were subjected to two dimensional gel electrophoresis followed by densitometric analysis and spot identification using MALDI mass spectrometry. Our study shows that few proteins such as albumin, alpha 1 antitrypsin, apolipoprotein A1, transferrin, transthyretin, haptoglobin and haemoglobin β chain were upregulated and inter alpha trypsin inhibitor heavy chain was downregulated in the disease samples. Further we have reported that some of these proteins show an association with disease severity. The present study marks the first step in the identification of new diagnostic markers as well as therapeutic targets.

BIOLOGICAL SIGNIFICANCE

Bladder carcinoma is the ninth most common cancer worldwide. It has gained attention within both clinicians and cancer biologists because of its recurrence and mortality rate. Identifying the prognostic factors of progression is a challenge, so that high risk patients who may be a candidate for a radical cystectomy may be identified. In this study we have attempted to study the changes observed in the urinary protein levels of urothelial neoplasm patients. The samples were graded based on p53 immunohistochemistry staining. We have reported eight (8) proteins, mostly highly abundant; those have exhibited differential regulation in case of diseased samples. This study is first of its kind that associates the changes in the urinary protein levels to that of the severity of the disease. We believe that the findings can be used as a stepping stone in the development of a noninvasive prognostic tool for the disease. This article is part of a Special Issue entitled: Proteomics in India.

IMAC fractionation in combination with LC-MS reveals H2B and NIF-1 peptides as potential bladder cancer biomarkers

Improvement in bladder cancer (BC) management requires more effective diagnosis and prognosis of disease recurrence and progression. Urinary biomarkers attract special interest because of the noninvasive means of urine collection. Proteomic analysis of urine entails the adoption of a fractionation methodology to reduce sample complexity. In this study, we applied immobilized metal affinity chromatography in combination with high-resolution LC-MS/MS for the discovery of native urinary peptides potentially associated with BC aggressiveness. This approach was employed toward urine samples from patients with invasive BC, noninvasive BC, and benign urogenital diseases. A total of 1845 peptides were identified, corresponding to a total of 638 precursor proteins. Specific enrichment for proteins involved in nucleosome assembly and for zinc-finger transcription factors was observed. The differential expression of two candidate biomarkers, histone H2B and NIF-1 (zinc finger 335) in BC, was verified in independent sets of urine samples by ELISA and by immunohistochemical analysis of BC tissue. The results collectively support changes in the expression of both of these proteins with tumor progression, suggesting their potential role as markers for discriminating BC stages. In addition, the data indicate a possible involvement of NIF-1 in BC progression, likely as a suppressor and through interactions with Sox9 and HoxA1.

A case with significant proteinuria caused by secreted protein from urothelial carcinoma

58-year-old female was admitted to our hospital complaining isolated proteinuria of 1.7 g/day. Abdominal echography showed right-sided unilateral hydronephrosis, and computed tomography pointed out a tumor of the right renal pelvis, suggesting cancer of renal pelvis. The right nephroureterectomy was carried out. Pathological diagnosis was urothelial carcinoma. Renal tissue revealed no apparent glomerulopathy with tubular atrophy, interstitial fibrosis, and mildly-to-moderately interstitial mononuclear cell infiltration. Immunofluorescence study showed no deposition of immunoreactanct, and electron microscopy showed almost normal glomerulus without electron dense deposit. Proteinuria disappeared within 6 days after the operation. Moderate amount of proteinuria in our patient was probably caused by secreted protein from urothelial carcinoma. This condition is rare but should be taken into account in patients with even moderate amount of proteinuria.

Identification of genes up-regulated in urothelial tumors: the 67-kd laminin receptor and tumor-associated trypsin inhibitor

Studies investigating changes in gene expression in urothelial carcinoma have generally compared tumors of different stages and grades but comparisons between low-grade, noninvasive tumors and normal urothelium are needed to identify genes involved in early tumor development. We isolated the urothelium from a low-grade tumor and corresponding normal mucosa by laser capture microdissection on frozen sections. The RNA extracted was amplified to generate suppressive subtractive cDNA libraries. Random sequencing of cDNA clones identified approximately 100 unique species. Of these 83% were known genes, 15% had homology to genes with an unknown function in humans, and 2% did not show homology to any published gene sequence. Two of the known genes, the 67-kd laminin receptor (67LR) and tumor-associated trypsin inhibitor (TATI), had previously been associated with metastatic progression in many tumor types, although 67LR has not been investigated in urothelial tumors. Immunolabeling of the original tissue with antibodies against these two genes confirmed overexpression, validating our strategy: 67LR was not expressed in the normal urothelium but was present in the tumor, whereas TATI expression was confined to umbrella cells in the normal urothelium, but extended to all cell layers in the tumor. We investigated both markers further in a separate series of tumors of different stages and grades. TATI was more consistently overexpressed than 67LR in all tumor grades and stages. Levels of secreted TATI were significantly higher in urine samples from patients with tumors compared to controls. Our strategy, combining laser capture microdissection and cDNA library construction, has identified genes that may be involved in the early phases of urothelial tumor development rather than with disease progression, highlighting the importance of comparing tumor with normal rather than just tumors of different stages and grades.

GL. Development of a novel proteomic approach for the detection of transitional cell carcinoma of the bladder in urine

Development of noninvasive methods for the diagnosis of transitional cell carcinoma (TCC) of the bladder remains a challenge. A ProteinChip technology (surface enhanced laser desorption/ionization time of flight mass spectrometry) has recently been developed to facilitate protein profiling of biological mixtures. This report describes an exploratory study of this technology as a TCC diagnostic tool. Ninety-four urine samples from patients with TCC, patients with other urogenital diseases, and healthy donors were analyzed. Multiple protein changes were reproducibly detected in the TCC group, including five potential novel TCC biomarkers and seven protein clusters (mass range, 3.3 to 133 kd). One of the TCC biomarkers (3.4 kd) was also detected in bladder cancer cells procured from bladder barbotage and was identified as defensin. The TCC detection rates provided by the individual markers ranged from 43 to 70% and specificities from 70 to 86%. Combination of the protein biomarkers and clusters, increased significantly the sensitivity for detecting TCC to 87% with a specificity of 66%. Interestingly, this combinatorial approach provided sensitivity of 78% for detecting low-grade TCC compared to only 33% of voided urine or bladder-washing cytology. Collectively these results support the potential of this proteomic approach for the development of a highly sensitive urinary TCC diagnostic test.

The utility of fibrin/fibrinogen degradation products in superficial bladder cancer

Fibrin/fibrinogen degradation products are either absent or present at exceedingly low levels in the urine of healthy persons. Although various nonspecific inflammatory conditions of the urinary tract can result in detectable amounts of FDP in the urine, the presence of FDP is far more prevalent in urine from patients with bladder cancer. Urinary FDP levels tend to be higher in patients with tumors of increasing grade and stage. This correlation results in improved sensitivity in detecting more aggressive tumors. Current monoclonal antibody immunoassays are simple, rapid, and inexpensive, and can be performed on urine samples in the clinical setting. The overall accuracy of these immunoassays ranges from 75% to 80% (Table 1), suggesting that the urine FDP test should not be used alone for the surveillance of superficial bladder cancer. When assays for urine FDP are combined with urine cytology, the sensitivity for detecting tumors is improved. Prospective data are needed to determine whether using these tests in combination can safely permit a reduced frequency of endoscopic surveillance.

Urinary concentrations of the soluble adhesion molecule E-cadherin and total protein in patients with bladder cancer

Reduced expression of the adhesion molecule E-cadherin has been associated with increased invasiveness and poorer survival in patients with bladder cancer. We have examined soluble E-cadherin (sE-cadherin) and total protein concentrations in urine from patients with bladder cancer (n = 34), non-neoplastic benign urological diseases (n = 14) and healthy controls (n = 21) to determine their diagnostic and prognostic significance. Soluble E-cadherin concentrations of the cancer group were significantly higher (P < 0.001) than those of the controls but the benign group was not significantly different from either the cancer group or the controls. When sE-cadherin concentrations were adjusted for creatinine, similar but more statistically significant results were obtained and the benign group was significantly elevated compared with the controls (P < 0.01). No differences were apparent between the invasive (pT1-4) and non-invasive (pTa) cancers. Urinary total protein concentrations in the cancer group were significantly higher than the controls (P < 0.001) and the benign group (P < 0.05) although no difference was seen between the benign group and patients with non-invasive (pTa) cancer or between the benign group and controls. When expressed as the protein/creatinine index, results were similar but more statistically significant and a significant difference was seen between invasive and non-invasive cancers (P < 0.01). Only the protein/creatinine index correlated significantly with stage of the tumour (P < 0.01). It is concluded that urinary sE-cadherin measurements are of no greater value than urinary total protein.

Increased immunodetection of acidic fibroblast growth factor in bladder cancer, detectable in urine

Acidic fibroblast growth factor is a regulatory peptide involved in cell proliferation, differentiation and motility. We used a polyclonal antiserum raised against purified native bovine acidic fibroblast growth factor, with no cross-reactivity for basic fibroblast growth factor to detect acidic fibroblast growth factor in tissue extracts and urine samples by means of a competitive enzyme immunoassay. Histochemical analysis was also performed on 10 specimens of normal urothelium and 50 of bladder cancer. Acidic fibroblast growth factor immunoreactive material was found in normal urothelium (1.77 +/- 2 ng./gm. tissue) and was increased more than 10-fold in patients with transitional cell carcinoma of the bladder (20.36 +/- 12 ng./gm. tissue). Immunohistochemical analysis localized immunoreactivity in the epithelial compartment of bladder tumors. Acidic fibroblast growth factor was assayed in urine from 579 individuals comprising a control group (114) and patients with benign prostatic hypertrophy (133), carcinoma of the prostate (96) or transitional cell carcinoma of the bladder (236). There was a significant difference in the frequency of urinary acidic fibroblast growth factor detection among the patients with invasive transitional cell carcinoma, the control group (p < 0.001) and the patients with prostatic disease (p < 0.01). The sensitivity was 72% and the specificity was 91%. Furthermore, the frequency of acidic fibroblast growth factor detection by enzyme immunoassay in the urine and the intensity of immunostaining was correlated with the stage of the disease. These data strongly suggest that acidic fibroblast growth factor is a potential marker for bladder tumors that may be of use in the noninvasive followup of patients with bladder cancer. We present a simple and reliable enzyme immunoassay for the detection of acidic fibroblast growth factor in voided urine that might be useful to quantitate this marker.

Transferrin receptor expression by human bladder transitional cell carcinomas

The expression of transferrin receptors (TFR) by normal and neoplastic urothelial cells was studied in "control" patients and in patients with transitional cell carcinoma of the bladder. These tumours were graded independently and consisted of 19 grade I, 30 grade II and 19 grade III lesions. TFRs were identified using a monoclonal antibody specific for TFR (OKT9) in an immunofluorescent or avidin/biotin-immunoperoxidase technique on fresh frozen sections. TFRs were not detected on normal urothelium. However, positive staining was found to increase with increasing pathological grade and stage of the tumours, ranging from 31.6% of grade I to 78.9% of grade III tumours and 51.2% of pTa (mucosa only lesions) to 87.5% of pT2/pT2+ (muscle invasion +/- deeper) primary urothelial malignancies.

Urinary fibrin/fibrinogen degradation products in transitional cell carcinoma of the bladder

Urinary fibrin/fibrinogen degradation products (FDPs) were measured in 210 specimens from 174 patients with newly or previously diagnosed transitional cell carcinoma of the bladder. They were detected in 94% of patients with deeply invasive bladder tumours (pT2-4) compared with 17% of superficial tumours. Microalbuminuria (greater than 50 micrograms/g creatinine) was also found in 80% of patients with pT2-4 lesions. Both were compared with urine cytology. Urinary FDPs are markers of bladder tumour invasion. Our results suggest that urinary FDPs are not of value in screening for the presence of bladder neoplasia but their role may be in following patients with superficial bladder tumours to detect those tumours which become invasive. The mode of excretion of the FDPs in the urine is discussed.

Normal and abnormal aspects of proteinuria. Part I: Mechanisms, characteristics and analyses of urinary protein. Part II: Clinical considerations

Part I highlights the mechanisms of glomerular filtration and tubular reabsorption of plasma proteins, selected characteristics of urinary proteins based upon electrophoretic properties and recent advances in clinical laboratory analysis of proteinuria. Both structural characteristic of the glomerular capillary wall and molecular properties of plasma proteins are important determinants of glomerular filtration. Proteins filtered by the glomerulus subsequently appear in urine only after escaping the efficient mechanisms of tubular reabsorption. Albumin is one such protein and constitutes the major protein in normal urine although trace amounts of alpha, beta, and gamma globulins are also detectable. Several techniques of protein analysis have thus been developed to specifically measure albumin as well as other plasma proteins. Other methods have been adapted to measure total urinary protein content enabling the clinician to readily monitor renal function in health and disease. The second part of this review will consider conditions associated with proteinuria in both asymptomatic individuals and patients with renal disease. Asymptomatic proteinuria encompasses states of excess protein excretion during conditions of orthostasis, exercise, travel to high altitude of fever. Proteinuria during renal disease has received considerable interest as a means to monitor kidney function. It is therefore classified according to the type of damage incurred: (1) glomerular-type where large molecular weight proteins are excreted (2) tubular-type where small molecular weight proteins are excreted and (3) mixed-type characterized by both large and small molecular weight proteinuria.