Abstract 1358: Tumor-derived extracellular vesicles as kidney cancer biomarkers

Abstract

Abstract Renal cell carcinoma (RCC) is a fairly common and lethal cancer. The wide variety of RCC histological subtypes constitutes a challenge in treatment decision-making. Exosomes are extracellular membrane vesicles that are produced by all cell types in physiological conditions. Extracellular vesicles (EVs) are now accepted as a mode of intercellular communication and transport proteins, RNAs, DNA, and lipids to surrounding and distant cells. The lipid bilayer membrane of the EVs helps to protect these cargos. EVs are involved in many pathological processes, such as cancer, and can be easily obtained through liquid biopsy. Currently, EVs are rarely considered as candidate biomarkers for kidney cancer. However, improvements in the characterization of tumor-derived EVs could lead to the implementation of blood- and urine-derived EVs as biomarkers in the management of oncologic patients. Since all organs, not just the tumor, contribute to EV population, the thoughtful discrimination of tumor-derived EVs remains an unmet need for the clinical application of this kind of liquid biopsy technology. To determine the contribution of the tumor to blood- and urine-derived EVs, we utilize a novel approach to isolate tissue-derived EVs in parallel with liquid biopsy-derived EVs. To our knowledge, only a handful of studies (only one in RCC) have studied EVs directly derived from tissue. We propose the use tissue-derived EVs to screen for candidate EV biomarkers in plasma and/or urine. We hypothesize that using tissue-derived EVs would increase the tumor specificity for the characterization of EVs as liquid biopsy biomarkers. We optimized a protocol in which we used tissue of RCC patients (normal kidney or tumor) to condition media and isolate tumor-derived EVs alone by ultracentrifugation. Additionally, we isolated plasma- and urine EVs by ultracentrifugation using standard protocols. Nanoparticle Tracking Analysis (NTA) showed normalized concentrations of >2 x 109 particles/mL with a size distribution in the small EV-range. Transmission Electron Microscopy (TEM) images showed typical exosome morphology, with the characteristic cup-shaped membrane vesicles. Western Blot (WB) confirmed the presence of exosome markers. We successfully isolated EVs from human RCC and healthy kidney tissue. We will proceed with screening the EV-samples for candidate miRNA-biomarkers by multiplexed gene expression analysis, followed by confirmation of the candidate markers by RT-qPCR. Citation Format: Richard C. Zieren, Liang Dong, Sarah R. Amend, Philip M. Pierorazio, Theo M. de Reijke, Kenneth J. Pienta. Tumor-derived extracellular vesicles as kidney cancer biomarkers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1358.