Abstract IA08: Incorporating proteomics in bladder cancer molecular diagnosis
Authors: Vlahou Antonia 
Published: August 2020

Proteins are directly linked to cell phenotype, hence accrue interest as biomarkers and therapeutic targets. Investigating the urine proteome as a source of biomarkers entails multiple technical challenges, with the main being the protein concentration vast dynamic range and presence of proteins in multiple modified forms. As a result, protein enrichment strategies in combination to different mass spectrometry platforms are regularly employed as main discovery tools, providing complementary experimental outputs. Verification and further biomarker validation regularly involve application of ELISA and, more recently, multiplex mass spectrometry (MS)-based assays (Multiple Reaction Monitoring–MS). In the course of this presentation, an overview of urine proteomics, as applied in bladder cancer research, will be provided. In brief, using the armamentarium of existing methodologic approaches, multiple urinary proteins have been associated with bladder cancer phenotypes and/or attributed prognostic or predictive value, including the Nuclear Matrix Protein 22 (NMP22) and Bladder Tumor Antigen (BTA; corresponding to complement factor H-related protein), approved by the FDA for use in disease diagnosis and/or surveillance. Additional proteins frequently reported in the literature as associated with bladder cancer detection and/or staging include various forms of apolipoproteins, proteins of the extracellular matrix (such as collagen and fibrinogen fragments), matrix metalloproteinases, cytokeratin fragments as well as proteins involved in apoptosis (such as survivin) or inflammation (including multiple cytokines). Reports also support potential of some of these proteins when evaluated in the form of biomarker panels, as predictors of BCG response in high-risk non-muscle invasive bladder cancer. Along these lines, simultaneous analysis of multiple markers through ELISA or mass spectrometry-based platforms has provided increased accuracies in comparison to single biomarkers. Hematuria is a frequent confounding variable in urinary protein measurements, rendering establishment of signal specificity via optimized ELISA assays or mass spectrometry platforms a current technological target. Direct links of urinary protein changes to bladder tissue events have been frequently reported (such as the cases of profilin 1 or activated leukocyte cell adhesion molecule). Even though disproportionate to the numerous reported findings (frequently compromised by suboptimal experimental design), collectively, promising urinary protein findings in association to bladder cancer phenotypes and contexts of use are existent, awaiting proper validation in large-scale prospective trials. Main research paths that now open up include: refinement of existing bladder cancer molecular subtypes, with the addition of information at the protein level, and placing urinary markers in this context; and, in parallel, design and running of proper validation studies as well as clinical sample sharing, to define optimal marker combinations per clinically relevant bladder cancer context of use. In the latter, special emphasis should be placed on prediction of treatment response, in order to maximize benefit from available treatment modalities.

Citation Format: Antonia Vlahou. Incorporating proteomics in bladder cancer molecular diagnosis [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr IA08.