Oncoprotein 18 is necessary for malignant cell proliferation in bladder cancer cells and serves as a G3-specific non-invasive diagnostic marker candidate in urinary RNA.

BACKGROUND: Urine-based diagnostics indicated involvement of oncoprotein 18 (OP18) in bladder cancer. In cell culture models we investigated the role of OP18 for malignant cell growth. METHODS: We analyzed 113 urine samples and investigated two human BCa cell lines as a dual model: RT-4 and ECV-304, which represented differentiated (G1) and poorly differentiated (G3) BCa. We designed specific siRNA for down-regulation of OP18 in both cell lines. Phenotypes were characterized by cell viability, proliferation, and expression of apoptosis-related genes. Besides, sensitivity to cisplatin treatment was evaluated. RESULTS: Analysis of urine samples from patients with urothelial BCa revealed a significant correlation of the RNA-ratio OP18:uroplakin 1A with bladder cancer. High urinary ratios were mainly found in moderately to poorly differentiated tumors (grade G2-3) that were muscle invasive (stage T2-3), whereas samples from patients with more differentiated non-invasive BCa (G1) showed low OP18:UPK1A RNA ratios. Down-regulation of OP18 expression in ECV-304 shifted its phenotype towards G1 state. Further, OP18-directed siRNA induced apoptosis and increased chemo-sensitivity to cisplatin. CONCLUSIONS: This study provides conclusive experimental evidence for the link between OP18-derived RNA as a diagnostic marker for molecular staging of BCa in non-invasive urine-based diagnostics and the patho-mechanistic role of OP18 suggesting this gene as a therapeutic target.

Comparative Tissue Proteomics of Microdissected Specimens Reveals Novel Candidate Biomarkers of Bladder Cancer.

More than 380,000 new cases of bladder cancer are diagnosed worldwide, accounting for ∼150,200 deaths each year. To discover potential biomarkers of bladder cancer, we employed a strategy combining laser microdissection, isobaric tags for relative and absolute quantitation labeling, and liquid chromatography-tandem MS (LC-MS/MS) analysis to profile proteomic changes in fresh-frozen bladder tumor specimens. Cellular proteins from four pairs of surgically resected primary bladder cancer tumor and adjacent nontumorous tissue were extracted for use in two batches of isobaric tags for relative and absolute quantitation experiments, which identified a total of 3220 proteins. A DAVID (database for annotation, visualization and integrated discovery) analysis of dysregulated proteins revealed that the three top-ranking biological processes were extracellular matrix organization, extracellular structure organization, and oxidation-reduction. Biological processes including response to organic substances, response to metal ions, and response to inorganic substances were highlighted by up-expressed proteins in bladder cancer. Seven differentially expressed proteins were selected as potential bladder cancer biomarkers for further verification. Immunohistochemical analyses showed significantly elevated levels of three proteins-SLC3A2, STMN1, and TAGLN2-in tumor cells compared with noncancerous bladder epithelial cells, and suggested that TAGLN2 could be a useful tumor tissue marker for diagnosis (AUC = 0.999) and evaluating lymph node metastasis in bladder cancer patients. ELISA results revealed significantly increased urinary levels of both STMN1 and TAGLN2 in bladder cancer subgroups compared with control groups. In comparisons with age-matched hernia urine specimens, urinary TAGLN2 in bladder cancer samples showed the largest fold change (7.13-fold), with an area-under-the-curve value of 0.70 (p < 0.001, n = 205). Overall, TAGLN2 showed the most significant overexpression in individual bladder cancer tissues and urine specimens, and thus represents a potential biomarker for noninvasive screening for bladder cancer. Our findings highlight the value of bladder tissue proteome in providing valuable information for future validation studies of potential biomarkers in urothelial carcinoma.

Expression of CD147, BIGH3 and Stathmin and their potential role as diagnostic marker in patients with urothelial carcinoma of the bladder.

BACKGROUND: Urothelial carcinoma of the bladder is characterised by very high recurrence rate, followed up by cystoscopy which being invasive technique makes the need for non-invasive markers important for Transitional Cell Carcinoma (TCC) detection. CD147 is a transmembrane protein highly expressed in tumour cells which aids in tumour invasion and growth. BIGH3, an Extracellular matrix protein (ECM) which interacts with various ECM component in different tissue system and Stathmin(STMN1) is cytosolic microtubule destabilising protein also called as Oncoprotein18 due to its role in tumour promotion. So far the expression of BIGH3 and STMN1 remains undetermined in cancer subjects including TCC. We therefore studied the levels and molecular expression of these molecules in TCC patients, to evaluate their usefulness as diagnostic markers. METHODS: Thirty consecutive TCC patients and two sets of control- 15 Benign prostatic hyperplasia (BPH) patient and 15 healthy were taken. Serum and urine levels of these molecules were estimated by ELISA and relative mRNA expression by Q-PCR from tumour and normal urothelium. Post-Hoc analysis and ROC curve were determined to evaluate the significance and sensitivity and specificity. RESULTS: The mean concentrations of these molecules were found to be significantly increased (p<0.001) in the serum and urine of TCC patients, with varying significance in each grade for different molecules. The urinary levels of CD147 (67 pg/ml) and serum STMN1 concentration (1.38 ng/ml) showed a specific increase as compared to the controls, while BIGH3 was elevated in both serum and urine samples. Molecular (mRNA) expression was elevated in the high grade (Muscle Invasive) stage of the disease for all the molecules, with a significant 3-fold increase that correlated with disease severity being observed for STMN1. ROC analysis gave optimal combination of sensitivity and specificity for diagnosis of the disease in urine and serum sample for STMN1. CONCLUSION: Of CD147, BIGH3 and STMN1, significant results were obtained for STMN1 and it could serve as the best possible diagnostic marker for TCC detection in future.