Abstract 4270: Differential expression of the αVβ3 integrin affects small extracellular vesicle cargo and promotes small extracellular vesicle pro-tumorigenic activity in vivo via its downstream effector, NgR2

Abstract It is known that small extracellular vesicles (sEVs) are released from cancer cells and contribute to cancer progression via crosstalk with recipient cells. These sEVs are being investigated as powerful biomarkers and possible therapeutic agents for prostate cancer (PrCa), which remains the leading cause of cancer death among men in the United States. We have previously reported that sEVs expressing the αVβ3 integrin, a protein upregulated in aggressive neuroendocrine prostate cancer (NEPrCa), contribute to neuroendocrine differentiation (NED) in recipient cells. sEVs used in this study were isolated by iodixanol density gradient and characterized by nanoparticle tracking analysis, immunoblotting, and single vesicle analysis. Our proteomic profile of sEVs containing αVβ3, when compared to control sEVs, shows a downregulation of typical effectors involved in apoptosis and necrosis, and an upregulation of tumor cell survival factors. This subset also contains an αVβ3 downstream effector, NgR2, a member of the Nogo receptor family and a novel marker for NEPrCa. We have previously shown that NgR2 promotes NED and cell motility, and upregulates RhoA, a protein associated with aggressive phenotypes of PrCa. In this study, we show that the expression of NgR2 increases tumor growth in vivo. We also show that the downregulation of NgR2 inhibits tumor growth and NED. Furthermore, we report that sEVs containing αVβ3 are loaded with higher amounts of NgR2 as compared to sEVs that do not express αVβ3. Mechanistically, we demonstrate that sEVs containing NgR2 do not affect the sEV marker profile, but, when injected in vivo intratumorally, they promote tumor growth and induce NED. We confirm that the transfer of NgR2 into recipient cells is sufficient to promote tumor growth and show that NgR2 mimics the effect of sEVs containing αVβ3 since it displays increased growth of NgR2 transfectants in vivo, as compared to control cells. Overall, our results describe a new mechanism mediated by sEVs containing αVβ3 and NgR2 that promotes cancer progression. Acknowledgements: NIH R01-CA224769; DoD W81XWH2210826 Citation Format: Cecilia E. Verrillo, Fabio Quaglia, Nicole Naranjo, Anna Testa, Lucia R. Languino. Differential expression of the αVβ3 integrin affects small extracellular vesicle cargo and promotes small extracellular vesicle pro-tumorigenic activity in vivo via its downstream effector, NgR2 abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4270.