Characterization of hTERT-immortalized Prostate-derived Stromal and Epithelial Cells: An Authentic In Vitro Model for Tumor Microenvironment Studies

Tumor development begins with mutational changes to the genetic makeup of a cell; tumor progression is not solely determined by the mutated cell but also by the tumor's microenvironment. Prostate cancer, a leading cancer diagnosed in men, has been determined to be highly influenced by its surrounding stroma, particularly fibroblasts. It has been demonstrated that cancer-associated prostate fibroblasts (CAFs) differ from normal-associated prostate fibroblasts (NAFs). However, human prostate cancer model systems have focused largely on prostate cancer epithelial cells. Currently, a need exists for a more physiologically relevant human cell model system to study prostate cancer progression within the context of its tumor microenvironment. In this study, we characterized 3 prostate-derived cells: CAFs, NAFs, and prostate epithelial cells (PrEs); all 3 lines were immortalized by(human telomerase reverse transcriptase (hTERT) alone, and have been continuously passaged for more than 40 PDL in our hands. Our data shows that the hTERT-immortalized CAFs proliferate faster than the NAFs; in addition, both CAFs and NAFs express fibroblast markers such as TE7 and alpha smooth muscle actin (α-SMA), while neither cell line expresses epithelial markers such as CK14. Both CAFs and NAFs also express elevated levels of α-SMA upon TGF-β stimulation. All 3 prostate-derived cells weakly express the prostate specific marker AR, and show similar markers staining after long-time passaging. Importantly, conditioned media collected from CAFs promotes tumor cell growth better than NAF conditioned media. In conclusion, CAFs, NAFs, and immortalized PrEs may provide a very valuable model system for the study of prostate cancer cell progression and tumor microenvironment studies.