Abstract B039: Influence of tumor-associated fibroblasts and their exosomes in the development and progression of prostate cancer

Abstract The unique tumor microenvironment (TME) of the prostate and in particular fibroblasts are known to play an essential role in the growth and progression of prostate cancer (PCa). Earlier studies from our group have shown that co-injection of patient-derived prostate cancer-associated fibroblasts (CAFs) and non-cancer associated fibroblasts (NCAFs) with tumor cells stimulated tumor growth in xenograft models compared to the injection of tumor cells alone. Our present study aims to investigate the effect of patient-derived prostate CAFs and NCAFs on the functional aspects of tumor cells in-vitro and their role in epigenetic regulation. Three prostate CAFs and NCAFs pairs were isolated from tissues of patients who had undergone radical prostatectomy and cultivated in-vitro. We then examined the influence of these fibroblast pairs on the viability, proliferation and migration of prostate cancer cell lines LNCaP and LNCaP C4-2. Cells were co-cultured in a transwell system with tumor cells in the lower chamber and fibroblasts in the upper chamber for 2 and 4 days and the viability of the tumor cells was measured using WST-1 assay and proliferation using BrdU colorimetric assay. For migration assay, the tumor cells were pretreated with serum-deficient medium and were co-cultured in a transwell system as mentioned above for 4 days. The tumor cells were collected after co-culture and the migration was measured using the transwell migration system as well as Xcelligence real-time assays in parallel. Further, extracellular vesicles (EV) were enriched from fibroblasts by ultracentrifugation. The expression of miRNAs isolated from cells and EVs was studied by microarray analysis and RT-qPCR. Patient-derived fibroblasts significantly increased the viability and proliferation of the tumor cells compared to the tumor cells alone. The influence of NCAFs on both viability and proliferation was more pronounced compared to CAFs on the LNCaP cells. However, the influence of the fibroblasts was vice versa on the LNCaP-C4-2 cells. The LNCaP cells exhibited no migration whereas the LNCaP C4-2 cells exhibited slight migration. The effect of different fibroblast pairs on the migration of LNCaP C4-2 cells varied among the pairs. 103 miRNAs and 6 miRNAs were found to be differentially expressed between CAFs and NCAFs and between their EVs, respectively. miR-10b-5p and miR-210-3p were confirmed by RT-qPCR to be upregulated in the CAFs. Our in-vitro data confirmed the in-vivo results. Fibroblasts modulate viability, proliferation and migration of PCa. However, the effects are heterogeneous due to patient and cell line-specific characteristics. Further studies will focus on the possible effects of fibroblasts on apoptosis in correlation to viability and invasion. CAFs and their EVs are characterized by specific miRNA expression supporting an epigenetic regulation of fibroblast characteristics and functions. Therefore, we will further investigate the mechanism of tumor progression induced by fibroblasts and their EVs via miRNA regulation. Citation Format: Aishwarya Tagat, Hiresh Ayoubian, Angela Zaccagnino, Michael Stöckle, Johannes Linxweiler, Kerstin Junker. Influence of tumor-associated fibroblasts and their exosomes in the development and progression of prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B039.