Differential Protein Expression And Mir Content Of Sorted Subsets Of Circulating Microvesicles From Cancer Patients And Healthy Controls

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL MicroRNAs (miRs) are small non-coding RNAs that are 20 to 25 nucleotides in length and regulate expression of entire families of genes. A major source of circulating miRs in cancer patients is believed to be circulating microvesicles (cMV) within biologic fluids such as blood. The transfer of these modifiers of RNA translation from diseased cells into the bloodstream can have broad impacts on disease detection, progression and/or prognosis. The goal of these studies was to determine whether there are differences in miR composition within different subpopulations of cMV based on surface protein composition. We used flow cytometry to phenotype and sort plasma-derived cMV from 20 individuals (3 breast cancer, 2 lung cancer, 6 prostate cancer, 1 bladder cancer and 6 non-cancer controls). cMV were stained for proteins associated with membranes such as tetraspanins (CD9, 63, 81) Ago2 and/or GW182 using a Beckman Coulter MoFlo XDP. For phenotypic analysis, events were gated on tetraspanin expression to distinguish cMV from nano-sized irrelevant debris, and co-expression of GW182 and Ago2 was determined. Quadrant-based sorting was performed for single- and double-positive events. miR content was determined using conventional Taqman probes with the ABI 7900 thermal cycler on extracted RNA from the sorted cMV. The results of these studies demonstrate that unfractionated cMV were not able to discriminate cancers from non-cancers using miRs-let-7a, -16, -22, -148a or -451 in this population of patients. When sorted tetraspanin+, Ago2+ and/or GW182+ populations of cMV were compared, miR expression was generally 5-fold higher in cancer patients than in healthy controls. These studies demonstrate that cMV can be consistently phenotyped, analyzed and sorted using a flow cytometer and that subpopulations of cMV contain unique miR profiles which can be useful in distinguishing cancer plasma from non-cancer plasma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3607. doi:1538-7445.AM2012-3607