Abstract B65: Proteomic and lipid characterization of exosomes derived from prostate cancer vs. benign cell lines yields potential novel biomarkers

Abstract Introduction: Prostate cancer is the leading type of cancer diagnosed in men. In 2010, approximately 217,730 new cases of prostate cancer were reported in the United States. Prompt diagnosis of the disease can substantially improve its clinical outcome. Improving capability for early detection, as well as developing new therapeutic targets in advanced disease are research priorities that will ultimately lead to better patient survival. Eukaryotic cells secrete proteins via distinct regulated mechanisms which are either ER/Golgi dependent or microvesicle mediated. The release of microvesicles provides a novel mechanism for intercellular communication. Exosomes are nanometer sized cup-shaped membrane vesicles which are secreted from normal and cancerous cells. They are present in various biological fluids and are rich in characteristic proteins. Exosomes may thus have potential both in facilitating early diagnosis via less invasive procedures or be candidates for novel therapeutic approaches for castration resistance prostate cancer (CRPC). In this study, we hypothesize that exosomes have a pivotal role in cell-cell communication in the local tumour microenvironment, conferring activation of numerous survival mechanisms during prostate cancer progression and development of therapeutic resistance. Exosomes may also facilitate prostate cancer diagnosis via less invasive procedures. Methods and Results: We isolated and purified exosomes derived from six prostate cell lines including PC3, DU145, VCaP, LNCaP, C4-2 and RWPE-1 using differential centrifugation followed by a final ultracentrifugation step in a 30% sucrose cushion. Exosomes purification was further confirmed using transmission electron microscopy and western blot analysis for known exosome markers. We then confirmed the transfer of exosomes to target cells (in both cancerous and benign prostate cell lines) in culture using confocal microscopy of fluorescence labeled exosomes. Finally, our comprehensive proteomic and lipidomic analysis of derived exosomes from all these six prostate cell lines shows that exosomes derived from specific prostate cancer cells present potential markers of prostate cancer progression. Conclusion: Taken together the comprehensive characterization of exosomes derived from different prostate cell lines including those which have AR +/−ve expression, versus a benign prostate cell line, forms a platform, not only for future clinical validation of these novel biomarkers for PCa diagnosis, but also to aid further investigation for possible therapeutic targets which could be important in the future treatment of CRPC. Citation Format: Elham Hosseini-Beheshti, Steven Pham, Hans Adomat, Emma S. (Tomlinson) Guns. Proteomic and lipid characterization of exosomes derived from prostate cancer vs. benign cell lines yields potential novel biomarkers [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B65.