ROLE OF STROMAL FIBROBLASTS INTERACTION WITH PROSTATIC CANCER CELLS IN ACHIEVEMENT OF METASTATIC PHENOTYPE.

Introduction & Objectives: Tumoral micro-environment, also called "reactive stroma", plays an important role in prostate cancer progression and in the achievement of a metastatic phenotype. Particularly, activated fibroblasts (AF) with an ex novo expression of a-SMA protein (smooth muscle actin), are supposed to enhance tumoral cell aggressive characters and metastatic capacity. Aim of our study was to analyze the biunivocal interaction between fibroblasts and prostatic cancer cells and to establish how tumoral cells achieve the aggressive and metastatic phenotype. Material & Methods: We performed cultures of fibroblasts, untransformed prostatic epithelial cells (PNT-1) were cultivated in RPMI medium and prostatic cancer cells (PC-3) were cultivated in DMEM medium to observe cell to cell interaction between those cells placed in contact among them. After 24 hours we separated the 2 cellular lines on the basis of their different times of plate adhesion. We used Boyden chamber for the tridimensional test of cells migration in DMEM 4500 medium (chemoattractive). Migrated cells that were found in filter pores, fixed and inked, were counted at microscope. Cellular invasion was evaluated by Boyden chamber with a filter containing matrigel to copy extracellular matrix. Results: We isolated among cancer-activated fibroblasts (CAF) the myofibroblasts, in addition to a-SMA negative fibroblasts (PC-AF) with a remarkable ability to enhance migration and invasiveness of PC3. Effects induced by MF and PCAF on invasive capacities of PC3 resulted different: MF induces a uPA/uPAr system mediated invasiveness, while PC-AF promotes a metalloprotease dependent invasiveness. IL-6 resulted to be able to induce trans-differentiation of fibroblasts in PC-AF. Our results show that activated fibroblasts determine an increase of invasiveness of PC3, while don't affect tumorigenesis. In primary cultures of prostatic fibroblasts, these can be activated either by TGF β in MF, and much more by IL6 in PCAF. Analysis of cancer associated fibroblasts (CAF) allowed us to confirm their facilitator role in tumour cell invasiveness. Conclusions: In our results we highlights the existence of a biunivocal cooperation between fibroblasts and prostate cancer cells, which was implemented by 1L6 or TGF β dependent manner, in promoting a metastatic and aggressive phenotype. Indeed, PC3 induce fibroblasts activation, with or without expression of ab-SMA, through the production of TGF β or IL6. These activated fibroblasts increase the aggressiveness of PC3 inducing a pro-invasive phenotype through the system dependent on uPA/uPAr or MMP.