Abstract C06: Multi-lineage differentiation potential of carcinoma-associated fibroblasts isolated from primary tumors of metastatic prostate cancer patients

Introduction: Extensive evidence demonstrates that the fibroblasts in tumors, often referred as carcinoma-associated fibroblasts (CAFs), are key players in prostate cancer (CaP) tumorigenesis, progression and metastatic spreading. However, only a percentage of CaP patients will progress to a metastatic disease, raising the question about the potential phenotypic and functional differences between CAFs present in primary tumors of metastatic CaP from those present in the confined disease. Recent studies in other solid tumors, have pointed that bone marrow-derived mesenchymal stem cells (MSC) within tumor microenvironment promote metastasis. In this study, we standardized a methodology to obtain primary cultures of human prostate stroma cells (HPSCs) from needle biopsies of the primary tumor of non-metastatic and metastatic CaP patients to investigate the presence of putative MSCs within the tissue microenvironment of these patients. Material and Methods: Primary cultures of HPSCs were obtained from explants of needle biopsies from the peripheral zone of: 1) primary tumor of patients undergoing radical prostatectomy without evidence of metastasis (CAFs), 2) primary tumors of metastatic CaP patients (mCAFs) and from patients without evidence of neoplasia (BAFs). HPSCs were characterized using gene expression profile, qPCR, immunocytochemistry and western blot. The functional role of mCAFs was evaluated measuring the effect of conditioned media (CM) on migration and invasion of CaP cell lines and by in vivo assays using co-injection of stroma-epithelium in immunodeficient mice. The presence of putative MSCs in HPSCs was determined by qPCR, immunocytochemistry and western blot for the expression of the MSCs markers CD73, CD90, CD105, CD166, CD44. and evaluating the capability of BAFs and mCAFs to differentiate into osteoblasts, chondrocytes and adipocytes. Results: Our results demonstrate that CAFs and mCAFs show an activated-phenotype assessed by in vitro and in vivo assays. However, the analysis of the gene expression profiles revealed that primary cultures of mCAFs are intrinsically different from CAFs associated to non-metastatic CaP. mCAFs exhibit an increase in the proportion of MSCs markers compared with cultures of BAFs and cultures of CAFs, unlike BAFs, are capable of multi-lineage differentiation but prone into osteoblasts differentiation. Discussion: Our results suggest that the existence of putative MSC within the primary tumor microenvironment of patients with metastatic CaP have a critical implication on the acquisition of the aggressive phenotype of the disease. Citation Format: Javier Cerda-Infante, Jenny Henriquez, Marianela Sanchez, Ralph Buttyan, Viviana P. Montecinos. Multi-lineage differentiation potential of carcinoma-associated fibroblasts isolated from primary tumors of metastatic prostate cancer patients. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr C06.