Therapeutic potential of plant-derived nanovesicles for neuroendocrine prostate cancer.

Abstract

186 Background: Neuroendocrine prostate cancer (NEPC) is a highly lethal variant of prostate cancer (PCa) that often emerges after androgen receptor (AR)-targeted therapies such as enzalutamide and abiraterone. NEPC arises via trans-differentiation of prostate adenocarcinomas to neuronal lineage, a process referred to as ‘neuroendocrine trans-differentiation’ (NED), wherein prostate cancer cells show an altered expression of lineage markers such as decreased expression of AR and increased expression of neuronal markers. Currently, there is a lack of effective targeted therapies for NEPC. Current treatment options are limited to highly toxic platinum-based drugs. Hence, there is an urgent need to develop novel treatment strategies to treat NEPC. The focused objective of this study is to develop novel, non-toxic therapeutic intervention against NEPC. Towards this, we exploited the potential of plant-derived nanovesicles/extracellular vesicles as a novel therapeutic. Extracellular vesicles (EVs) are lipid-bilayer-delimited particles that are released from almost all types of cells, including plant cells, typically between 30-150 nm in size. Methods: EVs/nanovesicles were isolated from plant-derived sources by ultracentrifugation. Isolated nanovesicles were characterized by Nanoparticle Tracking Analyses and electron microscopy. After characterization, the effects of nanovesicles were tested in NEPC cell lines in vitro. Effects on cell viability and apoptosis were assessed by MTS assay and flow cytometry, respectively. To understand the mechanistic basis of EV induced alterations, next generation RNA sequencing was performed in control vs EV treated NCI-H660 cells on Illumina HiSeq platform. Significant targets were further validated by real time PCR and Western blot analyses. Results: Plant-derived nanovesicles reduced viability and induced apoptosis in NEPC cell lines. Genes involved in ECM-receptor interaction, focal adhesion, proteoglycans in cancer and small cell lung cancer genes were significantly impacted by these vesicles in NEPC cell line. Remarkably, nanovesicles led to significantly attenuated levels of key proneural transcription factors including ASCL1, BRN2 and SOX2. In addition, neuronal markers ENO2 and NCAM1 were downregulated suggesting that treatment with nanovesicles reverse the ‘cardinal’ genetic alterations that drive NEPC. Conclusions: Plant-derived nanovesicles can be employed as a novel treatment modality in neuroendocrine prostate cancer.