Abstract 4154: Large oncosomes derived from the aggressive prostate cancer sub-line, DU145R80, can modify the biological behavior of the parental DU145 cells

Abstract

Abstract We have recently established a zoledronic acid-resistant prostate cancer cell line, DU145R80,which exhibits higher invasive capability compared to parental DU145 cells, and epithelial-to-mesenchymal transition (EMT)[Milone MR, Cell Death Dis. 2013]. To investigate the mechanism by which the cells become invasive, we compared DU145R80 and DU145 cells by a proteomic approach, unveiling a signaling network that links the interior of the nucleus to changes in cytoskeleton dynamics and to the extracellular matrix, dictating prostate cancer aggressiveness [Milone MR Oncotarget 2014].Cytoskeletal modifications allow cells to gain a more migratory/invasive behavior and to interact with the surrounding microenvironment triggering different kind of biological phenomena, including the formation of large oncosomes (LO), a bioactive class of extracellular vesicles (EVs) [Di Vizio D, Cancer Res. 2009]. In this study, we found a higher amount of spontaneously shed LO along with an increased gelatinase activity from DU145R80 cells compared to the parental counterpart. By applying low speed and discontinuous gradient ultracentrifugation to both DU145 and DU145R80 cell media, we obtained a pure preparation of LO, floating at a 1.15 g/mL density fraction and positive for LO markers such as as Cav-1, Ck18, GAPDH. Moreover, we treated DU145 parental cells with pure preparations of LO from either DU145 or DU145R80 cells and performed an invasion assay, showing that LO from the resistant, aggressive DU145R80 cell line increase the invading ability of DU145. Treatment of DU145 cells with LO originating from the parental cell line itself did not result in increased invasinevess, suggesting a specific role for EVs from aggressive cells. In addition, in order to investigate LO content, we focused our attention on a cell surface glycoprotein, CUB domain-containing protein 1 (CDCP-1), putatively linked to the network of proteins identified in DU145R80 cells and whose role in cancer is still under debate. Our results demonstrate that CDCP-1 expression is significantly reduced in DU145R80 compared to DU145 cells, suggesting a tumor-protective role for the protein in prostate cancer. We also observed, for the first time, that the CDCP-1 expression pattern displayed by both cell lines was reflected in their derived LO. These data intriguingly suggest that CDCP-1 may change its expression pattern upon modifications in tumor cells properties, playing a different role in different stages of cancer development. Overall, these findings highlight LO as a new biological component in the development of aggressive features by prostate cancer cells, connecting molecular alterations to changes in the ability to interact with the surrounding environment, and suggested new prognostic markers and/or therapeutical targets. Citation Format: Chiara Ciardiello, Valentina R. Minciacchi, Mariana Reis-Sobreiro, Maria R. Milone, Biagio Pucci, Rita Lombardi, Francesca Bruzzese, Dolores Di Vizio, Alfredo Budillon. Large oncosomes derived from the aggressive prostate cancer sub-line, DU145R80, can modify the biological behavior of the parental DU145 cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4154. doi:10.1158/1538-7445.AM2015-4154