Abstract 540: Identification of therapy resistance mediating extracellular vesicles in single-cell level via a novel microfluidic co-culture device development
Authors: Kim Chi-Ju , Amend Sarah , Pienta Kenneth 
Published: March 2024

Abstract
Once cancer has metastasized, it is incurable because tumors evolve resistance to all systemically administered anti-cancer therapies. Resistance to therapy has classically been attributed to the presence of a cancer stem cell or genetic tumor cell heterogeneity. Extracellular vesicles (EVs) are nano-sized (40-1000 nm) vesicles that are released by all cells into the extracellular space. EVs carry diverse cargo dependent on the cell of origin and have been studied as a source of novel cancer-specific liquid biopsy biomarkers and contributors to tumor progression and metastasis. However, the paracrine function of EVs in promoting therapy resistance is under-studied, and the impact of EVs released from therapy-resistant cancer cells on surrounding therapy-sensitive cancer cells is unknown. In this study, we develop an innovative microfluidic device, TREVCo, to enable simultaneous single-cell trap, EV detection, and co-culture modules to evaluate EVs-mediated transfer of cellular information between therapy-resistant cancer cells and adjacent cells, and to characterize EVs released from resistant cells and determine their impact on the resistance phenotype of adjacent therapy-sensitive cancer cells. We utilize resistant cells from multiple prostate (PCa) cell lines that have been selected for therapy resistance by culture with increasing dosages of cancer drugs such as cisplatin, docetaxel. We use the matched untreated therapy-sensitive parental cell lines as the sensitive cells. We hypothesize a novel model of therapy resistance in lethal PCa: EVs released from resistant cells contain pro-resistance factors that are transferred to adjacent sensitive cells upon EV uptake, thus directly enabling therapeutic resistance. We will assess the impact of resistant cell-EVs at a single cell level via a novel device, TREVCo, that enables comprehensive downstream analysis. This single-cell approach enables dissection of critical EV-associated therapy-resistant factors within the large heterogeneity of resistant PCa. Co-culture of a single resistant cell and a hundred adjacent sensitive cells mimicking intra-tumoral interactions is also critical to demonstrate evidence of resistant cell secreting factors inducing a pro-resistance phenotype. These studies will be the first-in-field to assess the impact of resistant PCa cell-derived EVs at single-cell resolution. An understanding of resistant cell-derived EVs and the impact of that EV cargo on adjacent sensitive cells will provide critical insight into the acquisition of therapy resistance in lethal PCa. The novel approach to apply resistant cell-derived EVs in co-culture assay with sensitive cells will enable the screening of transmittable resistance-associated factors and provides critical opportunities for accelerating precision medicine for advanced PCa patients.
Citation Format: Chi-Ju Kim, Sarah Amend, Kenneth Pienta. Identification of therapy resistance mediating extracellular vesicles in single-cell level via a novel microfluidic co-culture device development [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(6_Suppl):Abstract nr 540.