Oral Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Osteoblastic metastatic lesions are found in over 90% of patients with metastatic castrate resistant prostate cancer (mCRPC). While current drugs in that stage present with poor survival advantages (< 5 months), androgen receptor (AR)-targeted therapies (ATT) continue to be the gold standard for recurrent advanced disease, even when the cancer has established in the bone. Yet, ATT ultimately involve both cancer cell and stroma adaptation through a combination of AR reactivation and paracrine signalling, with most processes currently unknown in the bone microenvironment. To address this issue, adequately modelling the pathology of the disease in the laboratory becomes paramount. In our previous work, using additive biomanufacturing, we have developed a reproducible microtissue-engineered human 3D model of osteoblastic metastases, that comprises primary osteoblasts, osteocytes and cancer cell lines, able to display some functional and molecular features, as observed in clinical androgen-deprived cancer. In the current study, we used the bone metastasis model to determine the quantitative effects of a first-generation (bicalutamide) and a second-generation (enzalutamide) ATT, combining 4D live microscopy, cell morphometry, gene and protein analysis (Figure 1). We showed how anti-androgen treatments increased cancer cell volume and reduced sphericity, correlating with a more adaptive phenotype, and how reduced mineralization increased cancer cell migration. Anti-androgen treatments also affected the proliferation and migration of AR-dependent-, but not AR-independent- cell lines, at both 48h and after 3 weeks of co-culture. Dysregulation of markers under these treatments was significant with AR-dependent LNCaP cell-line, including included RUNX2, OPN and BSP upregulation, correlated with increased osteoblastic activity, while also increasing epithelial-to-mesenchymal (SLUG) and neuroendocrine markers (DDC), linked to a more adaptive phenotype. Ultimately the model and innovative quantitative methodologies unravelled the detrimental effects anti-androgens therapies may have on AR-dependent bone metastases, presenting a powerful platform to study cancer cell behaviour in any therapeutic context.