TRANSFORMING GROWTH FACTOR-β1 INDUCED MYOFIBROBLASTS REGULATE LNCaP CELL DEATH

Abstract

Reactive stroma represents a generic wound response phenomenon, which has been identified in areas of tissue injury and carcinogenesis. To determine whether reactive stroma influences prostate tumor cell growth 3 primary prostate stromal cell lines were treated with transforming growth factor-β1 (TGF-β1) to induce the reactive stroma phenotype and then co-cultured with LNCaP cells. Flow cytometry was performed in LNCaP cells that had been co-cultured with induced reactive stroma or control stroma and an index of cell death and proliferation was obtained. Using the previously described 3 way differential reactive stroma xenograft tumor model consisting of LNCaP cells, stromal cells and Matrigel (Collaborative Research, Bedford, Massachusetts) LNCaP cell apoptosis was evaluated using TUNEL staining in a background of varying degrees of reactive stroma. Flow cytometric analysis revealed that LNCaP cells co-cultured with TGF-β1 induced stromal cells demonstrated a significantly decreased rate of cell death compared with controls (p <0.001). In an animal model LNCaP cells of the 3 way xenograft constructs treated with TGF-β1 latency associated peptide, an inhibitor of TGF-β1, showed increased apoptosis by TUNEL staining (p <0.001). Double label immunohistochemistry analysis demonstrated that TGF-β1 induced stromal cells had an increased proportion of myofibroblasts, the identifying cell type of reactive stroma. Furthermore, the degree of reactive stroma inversely corresponded to the degree of LNCaP cell death. These findings indicate that reactive stroma influences prostate cancer cell growth and warrant investigation of the regulatory mechanisms between reactive stroma and prostate cancer cells.