Abstract 2015: A transcriptionally enhanced biosensor to detect and monitor biopsy-dissociated primary prostate cancer single cell drug responses by bioluminescence microscopy
Authors: Champagne Audrey , Jain Pallavi , Neveu Bertrand , Pouliot Frédéric 
Published: September 2020

Abstract
Background: In the past decade, the therapeutic landscape of metastatic castration resistant prostate cancer (mCRPC) has been transformed with the introduction of novel pharmaceutical agents including novel antiandrogens (nAA) such as darolutamide, enzalutamide or apalutamide. Currently, the management of mCRPC is mainly based on biomarkers obtained from the patient's blood or bulk tumor samples, which do not take into account for prostate cancer (PCa) cell heterogeneity.
Objectives: To develop a bioluminescence imaging technology enabling: 1) the detection of PCa single cells from dissociated biopsies and 2) single cell nAA sensitivity assessment.
Methods: The PCA3 promoter (PCa specific) and PSEBC promoter (androgen receptor-driven to monitor response to nAA therapy) have been incorporated in the non-replicating adenoviral multi-promoter integrated two-step transcriptional amplification system (MP-ITSTA) that allows imaging of complementary activities of two different promoters by a single output reporter gene. Thus, PCA3/PSEBC-ITSTA system was designed to monitor androgen receptor (AR) activity specifically within each single PCa cell by bioluminescence microscopy. Prostatic biopsies were dissociated in the presence of collagenase II and DNase for 18h. PCa cell lines or fresh biopsies-dissociated cancer cells were transduced for 72h and then covered with an extracellular matrix gel. Single cell bioluminescence microscopy images were done before and after exposure to DHT or DHT+AA to specifically monitoring therapy response. Changes in cell number and luminescence intensity after AA were normalized to the DHT group to exclude non-specific cell-death due to infection or time spent in culture.
Results: PCA3/PSEBC-ITSTA was specific to PCa cell lines. By determining the ratio of AR active cells before and after DHT or DHT+AA treatment in culture, PCA3-Cre-PSEBC-ITSTA was able to determine the AA sensitivity of LNCaP (sensitive), LAPC4 (moderately resistant) and 22Rv1 (resistant) PCa cell lines. Also, our method could detect and monitor AA sensitivity of primary PCa cells harvested from eight radical prostatectomy specimens. PCA3/PSEBC-ITSTA could dynamically quantify AR transcriptional activity during enzalutamide or bicalutamide treatments, in a dose dependent manner, and could unveil tumor AA response heterogeneity. As expected, inhibition of AR activity was stronger with enzalutamide than with bicalutamide.
Conclusions: Our bioluminescence microscopy-based biosensor could detect primary PCa cells in culture and it allows dynamic evaluation of AA sensitivity at a single-cell level in a heterogeneous cell population harvested from radical prostatectomy biopsies. We believe our approach opens to a novel field of treatment response predictive tools for cancer treatment decision-making.
Citation Format: Audrey Champagne, Pallavi Jain, Bertrand Neveu, Frédéric Pouliot. A transcriptionally enhanced biosensor to detect and monitor biopsy-dissociated primary prostate cancer single cell drug responses by bioluminescence microscopy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2015.