Abstract 4764: Development of a multigenic bioluminescence imaging system to detect prostate cancer cells and assess their response to therapy
Authors: Jain Pallavi , Neveu Bertrand , Fradet Yves , Pouliot. Frédéric 
Published: July 2016

Abstract
BACKGROUND
Currently, liquid biposies for imaging single cancer cell to provide personalised medicine is gaining importance. In the last years, molecular imaging techniques using transcriptional amplification systems have been developed but a system enabling both PCa cell detection and treatment response assessment is lacking. PCA3 RNA is a unique PCa biomarker that has been widely studied for PCa screening and detection while the PSA gene is another biomarker of high clinical significance as it gives an account of response to androgen deprivation treatments (ADT). In this study, we have developed and studied an imaging system based on the combined transcriptional activities of the PCA3 and PSA gene promoters for single PCa cell detection and ADT response assessment from patients body fluids.
METHODS
Adenoviruses (Ad) were constructed utilizing the ability of site-specific recombination of the Cre-Lox system. The PCA3 and PSA promoters were integrated into a single Ad backbone with one promoter driving the expression of CRE recombinase and the other driving the Two Step Transcriptional Amplification system and the Firefly luciferase gene (fl) to generate a new system that we named the Multigenic Integrative Transcriptional Amplification System (MP-ITSTA). PCa cells specificity and ADT response was tested by transient infection. To detect cells in body fluid, 22Rv1-GFP cells were spiked in urine or blood of healthy control, infected with MP-ITSTA after purification and single cell imaging was done using the LV200 bioluminescence microscope.
RESULTS
We show that the PCA3-TSTA driven fl expression is specific to PCa cells (22Rv1, LAPC4, PC3, DU145) giving 8.5-108.4 fold higher expression when compared to SW780 bladder cancer cells. Contrary to PCA3-TSTA, the PSA-TSTA activity is regulated by androgen treatment but is not prostate cancer-specific as it is active in AR responsive breast cancer cells (CAMA-1 and ZR-75). We show that MP-ITSTA reporter expression is dependent on the combined activation of two promoters (PCA3 and PSA promoter) in a DHT dependent manner. MP-ITSTA could therefore also give an account of responsiveness to bicalutamide or enzalutamide treatments PCa cells. The signal obtained by MP-ITSTA system is 2.3 and 1.6 times higher than PCA3-TSTA in 22Rv1 and LAPC4, respectively proving that MP-ITSTA has the ability to enhance the reporter gene expression from a weak but PCa specific PCA3 promoter. Finally, MP-ITSTA could specifically target spiked 22Rv1-mcherry cells isolated from urine while no signal was found in non-spiked samples.
CONCLUSIONS
MP-ITSTA therefore represents a prostate cancer specific and non-invasive tool to target with high accuracy PCa cells and to detect their response to ADT cell per cell from body fluids.
Citation Format: Pallavi Jain, Bertrand Neveu, Yves Fradet, Frédéric Pouliot. Development of a multigenic bioluminescence imaging system to detect prostate cancer cells and assess their response to therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4764.