Biomarkers for detection and surveillance of bladder cancer.

INTRODUCTION: Bladder cancer is the fourth most common cancer in men and the ninth most common cancer in women in Canada. Early detection of tumours is essential for improved prognosis and long-term survival. The standard method for detection and surveillance is cystoscopy together with urine cytology. Cystoscopy is relatively sensitive but is expensive and invasive. Urinary cytology is a noninvasive method that has poor sensitivity but high specificity; it is relied on for the detection of carcinoma in situ. Currently, several urinary-based bladder tumour biomarkers with USFDA/Health Canada approval are available commercially, but none have been widely adopted by urologists despite their offering high sensitivity and/or specificity. We present here a review of recent studies evaluating 7 commercial biomarker assays for the detection and/or surveillance of bladder cancer. RESULTS: SENSITIVITY AND SPECIFICITY RANGES, RESPECTIVELY, FOR EACH MARKER WERE REPORTED AS FOLLOWS: BTA Stat (Polymedco), 52.5%-78.0% and 69.0%-87.1%; BTA Trak (Polymedco), 51%-100% and 73%-92.5%; cytology, 12.1%-84.6% and 78.0%-100%; hematuria dipstick, 47.0%-92.6% and 51.0%-84.0%; NMP22 Bladder Cancer Test (Matritech), 34.6%-100% and 60.0%-95.0%; NMP22 BladderChek (Matritech), 49.5%-65.0% and 40.0%-89.8%; ImmunoCyt/uCyt+ (DiagnoCure), 63.3%-84.9% and 62.0%-78.1%; ImmunoCyt/uCyt+ and cytology, 81.0%-89.3% and 61.0%-77.7%; and UroVysion (Abbott Molecular)/florescence in situ hybridization, 68.6%-100% and 65.0%-96.0%. CONCLUSION: We find that no currently available bladder cancer urinary marker is sensitive enough to eliminate the need for cystoscopy. In addition, cytology remains integral to the detection of occult cancer. However, owing to their relatively high sensitivities, these markers may be used to extend the period between cystoscopies in the surveillance of patients with transitional cell carcinoma. Further study is required to determine which markers, alone or in panel, would best accomplish this.

Subcellular proteomics of cell differentiation: quantitative analysis of the plasma membrane proteome of Caco-2 cells.

Human colorectal carcinoma (Caco-2) cells undergo in culture spontaneous enterocytic differentiation, characterized by polarization and appearance of the functional apical brush border membrane. To provide insights into the biology of differentiation, we have performed a comparative proteomic analysis of the plasma membranes from proliferating cells (PCs) and the apical membranes from differentiated cells (DCs). Proteins were resolved by SDS-PAGE, in-gel digested and analyzed by RP-LC and MS/MS. Alternatively, proteins were digested in solution, and tryptic peptides were labeled with isotopic tags and analyzed by 2-D LC followed by MS/MS. Among the 1125 proteins identified in both proteomes, 76 were found to be significantly increased in the membranes of DCs and 61 were increased in PCs. Majority of the proteins increased in the apical membranes were metabolic enzymes, proteins involved in the maintenance of cellular structure, transmembrane transporters, and proteins regulating vesicular transport. In contrast, majority of the proteins increased in the membranes of PCs were involved in gene expression, protein synthesis, and folding. Both groups contained many novel proteins with yet to be identified functions, which could provide potential new markers of the intestinal cells or of colorectal cancer.

Outer membrane proteome of Actinobacillus pleuropneumoniae: LC-MS/MS analyses validate in silico predictions.

The Gram-negative bacterial pathogen Actinobacillus pleuropneumoniae causes porcine pneumonia, a highly infectious respiratory disease that contributes to major economic losses in the swine industry. Outer membrane (OM) proteins play key roles in infection and may be targets for drug and vaccine research. Exploiting the genome sequence of A. pleuropneumoniae serotype 5b, we scanned in silico for proteins predicted to be localized at the cell surface. Five genome scanning programs (Proteome Analyst, PSORT-b, BOMP, Lipo, and LipoP) were run to construct a consensus prediction list of 93 OM proteins in A. pleuropneumoniae. An inventory of predicted OM proteins was complemented by proteomic analyses utilizing gel- and solution-based methods, both coupled to LC-MS/MS. Different protocols were explored to enrich for OM proteins; the most rewarding required sucrose gradient centrifugation followed by membrane washes with sodium bromide and sodium carbonate. This protocol facilitated our identification of 47 OM proteins that represent 50% of the predicted OM proteome, most of which have not been characterized. Our study establishes the first OM proteome of A. pleuropneumoniae.