Biological significance of novel populations of prostate cancer circulating tumor cells (CTC).

315Background: Decisions regarding selection and sequencing of treatment in advanced prostate cancer (PC) are often made empirically, without information on the PC molecular profile at the time of treatment. CTC provide real time information regarding contemporaneous biologically relevant cancer subtypes. Current assays often rely on EpCAM or other epithelial markers and may underestimate or exclude other CTC populations of clinical relevance. We devised a novel, simple, rapid and cheap method for isolation of CTC subsets including those without epithelial markers. Methods: Five mL of blood was processed as follows: CD45+ depletion (RosetteSep Human CD45 Depletion Cocktail, Stemcell Technologies); Ficoll centrifugation; antibody staining (mix of EpCAM-PE, PSMA-APC, N-cadherin-AF488, E-cadherin-PerCP/Cy5.5, CD45-APC-H7); Sytox Blue live/dead cell stain; followed by sorting (Becton Dickinson FACSAria Fusion cell sorter). Live cells were sorted into 4 categories denoted E, E+P, P, N (Table). N and P are not ...