Abstract 1083A: An ex vivo 3D bone metastasis model for prostate cancer

Abstract

Abstract Introduction: Bone is the preferred site for prostate cancer (PCa) metastases and there is virtually no cure once the tumor is established within this niche. The development of therapeutic strategies against metastatic PCa has been limited by the lack of an all-human preclinical model to: (1) study PCa-bone interactions under physiologically relevant three dimensional (3D) microenvironments, (2) understand how these interactions result in the development of drug resistance, and (3) explore paradigm-changing precision medicine concepts. Methods: Conditionally reprogrammed primary PCa cells (CR-PCa, derived from a lymph node metastatic site) were integrated with our ex vivo human 3D bone tissue platform, as a transformative approach for modeling tumor behavior at the bone niche. The 3D bone tissue was engineered using primary osteoblastic (OSB) cells from human bone samples. These cells were biomimetically assembly with biphasic calcium phosphate microbeads (BCPm) in perfusion microfluidic culture devices. BCPm were used to replicate the 3D cellular network of OSTs in human bone. This 3D tissue model was successfully used to support the osteocytic differentiation of primary human OSB cells within the BCPm structure, while maintaining a single cell layer of osteoblasts on the surface of the 3D tissue resembling the bone endosteum. Results: Integration of the 3D bone tissue with CR-PCa cells resulted in a compromised endosteal layer after only 4 days of coculture, with more apoptotic OSTs in the tissues with CR-PCa vs. no PCa cells controls (P<0.01). For functional analysis, we stained 5 μm sections of the 3D tissues for alkaline phosphatase (ALP, an OSB marker) and sclerostin, an osteocytic marker and major signaling molecule released by embedded OSTs that suppresses osteoblastogenesis. Quantification of immunofluorescence staining revealed that ALP was significantly increased (P<0.05), whereas sclerostin significantly decreased (P<0.01) with the introduction of CR-PCa cells. This OSB phenotype, induced by PCa-bone interactions ex vivo, is entirely consistent with the OSB prostate cancer-bone metastasis niche seen in patients with advanced disease. Conclusions: Our model recapitulates: (1) an OSB monolayer closely resembling the endosteum at the bone/ bone marrow interface, (2) the complex microphysiological features and functions of 3D-networked OSTs, and (3) the interactions of primary PCa cells with osteoblasts and OSTs. Citation Format: Jenny Zilberberg, Saba Choudhary, Eugenia Dziopa, Cirian Mannion, Yair Kissin, Erika Parasido, Christopher Albanese, Woo Lee. An ex vivo 3D bone metastasis model for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1083A.