7 PSA-Isoforms-Velocity. Evaluation of a novel approach in the early diagnosis of prostate cancer. Results from the Tyrol PSA screening project

Abstract

specimens obtained after resection from patients with biopsy-proven prostate cancer and identify the targeted biomarker. METHODS: The nanodevice is a self-assembling system composed of DNA methyltransferase-thioredoxin fusion proteins covalently linked to a three arm DNA scaffold. Serial sections of frozen prostate tumor specimens of prostate cancer or BPH were placed onto slides and the tumor sections were incubated with varying concentrations of nanodevice in PBS and 1% BSA. Binding fluorescence was observed at 100x with a Zeiss Observer microscope and images of the entire tumor section were obtained by tiling individual pictures. Adjacent sections were immunohistochemically stained with H&E, monoclonal antibodies to -smooth muscle actin and thioredoxin reductase 1 and 2. RESULTS: Frozen tissue sections from 41 patients who underwent robot assisted-prostatectomy were studied. Nine showed significant fluorescence from the reactive stroma surrounding the tumor focus when exposed to the nanodevice. Using the tiled images, we identified the tumor and the region surrounding the tumor as reactive stroma using H&E and Masson s Trichrome. In order to attempt to identify the nanodevice target, the thioredoxin reductase 2 antibody was used to stain tissue sections adjacent to those studied with the nanodevice using immunohistochemistry. The stain was found to overlap the regions stained by the nanodevice, thus identifying this dimeric reductase as a target of the nanodevice in stromal cells in tumor. CONCLUSIONS: We have developed a nanodevice that binds selectively to the reactive stroma in freshly-frozen prostate tissue biopsy specimens obtained from robot-assisted prostatectomies. We indentified thioredoxin reductase 1 and 2 as potential biomarkers of reactive stroma in the tumor microenvironment using the nanodevice.