Abstract B14: uPAR expression in the microenvironment of human urothelial neoplasia of the bladder is associated with invasive behavior and increases significantly with T-stage and grade
Authors: Dohn Line Hammer , Illemann Martin , Høyer-Hansen Gunilla , Maase Hans von der , Christensen Ib Jarle , Litlekalsoey Jorunn , Hoestmark Jens G. , Pappot Helle , Laerum Ole Didrik 
Published: August 2014

Introduction and objectives: More than 90% of bladder tumors are urothelial neoplasias, characterised as heterogeneous cell populations consisting of tumor cells, macrophages and stromal cells. At time of diagnosis, most neoplasias are non-invasive (stage Ta) or with invasion of lamina propria (stage T1). Despite advances in surgical techniques and intra-vesical therapy, patients with stage Ta and T1 have high recurrence and progression rates. Pathologic stage and grade, have limited ability to predict the invasive and metastatic potential, probably due to tumors of similar stage and grade having a significantly different biology. Biomarkers discriminating the microenvironment in non-invasive from invasive neoplasia are needed in order to improve curability. For this reason we have investigated one of the key players in proteolytic activity of invasive neoplasias, the plasminogen activation system. Components of this system: urokinase plasminogen activator (uPA), its cellular receptor (uPAR) and inhibitor (PAI-1), have prognostic, diagnostic and/or predictive value in several human cancers, but are poorly investigated in urothelial cancer.

Materials and methods: Retrospectively collected, formalin fixed and paraffin embedded tissue samples (Haukeland University Hospital, Bergen) from 107 patients who underwent cystectomy for urothelial neoplasias in the period 1988-2005 were investigated. The material consists of 10 Ta, 24 T1, 73 T2-4 tumors, including 39 low-grade (LG) and 68 high-grade (HG) tumors.

uPAR expression was investigated by immunohistochemistry using a polyclonal antibody against uPAR. uPAR expression was evaluated as either negative or positive. All cases were re-diagnosed by the same pathologist. Cancer cells were identified by staining for cytokeratin (CK-pan and CK7 combined), macrophages by CD68 and tumour associated myofibroblasts by α-smooth muscle actin (α-SMA).

Results: 7/10 (70%) of the non-invasive neoplasias (stage Ta) showed no uPAR-immunoreactivity. The uPAR positive cells were only found in the surrounding stroma and not in cancer cells.

In the neoplasias showing stromal- (stage T1) or muscular invasion (stage T2-T4), uPAR-positivity was found in 14/24 (58%) and 63/73 (86%) respectively.

uPAR-positivity was found in 58/68 (85%) of HG tumors and in 17/39 (44%) LG tumors (p&lt;0.001). uPAR-immunoreactivity was primarily seen in fibroblast-like cells (presumably myofibroblasts) and to a lesser extent in macrophages in the surrounding stroma as well as in some scattered cancer cells.

There was a significant trend between uPAR-positivity and T-stage for cancer cells, macrophages and myofibroblasts (p&lt;0.001). High correlations have been shown between uPAR-expression in tumor core and the invasive front for all three cell types (rs&gt;0.57).

Conclusions: This study demonstrated that uPAR-positivity in the complex microenvironment of human urothelial neoplasia of the bladder significantly increases with T-stage and grade.

Myofibroblasts and macrophage expression of uPAR may be an early marker for invasive potential in urothelial neoplasia of the bladder. This may help in the identification of T1 neoplasias with high invasive potential.

The expression of uPAR, as well as PAI-1 and uPA, will be investigated in a larger material and correlated with survival/clinical data. Our aim is to establish predictive and prognostic tools for use in clinical setting based on semi-quantitative immunohistochemical methodology.

Citation Format: Line Hammer Dohn, Martin Illemann, Gunilla Høyer-Hansen, Hans von der Maase, Ib Jarle Christensen, Jorunn Litlekalsoey, Jens G. Hoestmark, Helle Pappot, Ole Didrik Laerum. uPAR expression in the microenvironment of human urothelial neoplasia of the bladder is associated with invasive behavior and increases significantly with T-stage and grade. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B14.