Abstract

sEV Sub-populations Derived from Cancer Cells that Express the AlphaVBeta3 Integrin

Cecilia Verrillo, Master's Student, Thomas Jefferson University

Small extracellular vesicles (sEVs) released from prostate cancer (PrCa) cells contain pro-tumorigenic cargo and are crucial components of cellular crosstalk.  The AlphaVBeta3 integrin is expressed in PrCa sEVs.  The primary goal of this project was to identify the impact of AlphaVBeta3 expression and associated proteins in sEVs derived from PrCa cells.  sEVs were isolated by differential ultracentrifugation followed by density gradient separation. After separation, sEVs were characterized by NTA, western blot analysis, and single vesicle analysis by Exoview.  While there are no differences in tetraspanin compositions of sEVs isolated from C4-2B AlphaVBeta3+ compared to C4-2B Mock cells, the expression of AlphaVBeta3 in C4-2B PrCa cells results in a distinct shift to low density sEVs.  These sEVs contain novel pro-tumorigenic cargo molecules: NgR2 and PD-L1, an effector of AlphaVBeta3 and a key player in immune evasion, respectively.  AlphaVBeta3/NgR2+ sEVs increase NgR2 expression upon transfer to recipient cells.  sEVs isolated from PrCa cell lines and mouse models of PrCa also specifically express six-transmembrane epithelial antigen of the prostate 1 (STEAP1), a metalloreductase upregulated in PrCa and not its family members STEAP2 or STEAP3.  Overall, our results show that AlphaVBeta3 expression is a key regulator of sEV density and pro-tumorigenic cargo loading.