Expression of p75(LNGFR) and Trk neurotrophin receptors in normal and neoplastic human prostate

Objective To analyse the occurrence and cell distribution of p75(LNGFR) and Trk neurotrophin receptors in normal prostate, benign prostatic hypertroph y (BPH) and prostate carcinoma, and to determine the effect of androgen sup pression on the expression of these proteins in prostate cancer samples. Materials and methods The study comprised formalin-fixed and paraffin-embed ded material, obtained during surgery and from cadavers during removal of o rgans for transplantation. Light microscopy immunohistochemistry was carrie d out using polyclonal antibodies against Trks, and a monoclonal antibody a gainst p75(LNGFR). General markers for epithelial and endocrine cells were assessed in parallel, Results TrkA immunoreactivity (IR) was restricted to the basal epithelial c ells in some acini (37%), This pattern remained unchanged or IR extended to the whole acini in BPH and varied widely in prostate cancer, In normal tis sue and BPH, TrkC IR was detected exclusively in the stroma, Nevertheless, it progressively increased in the epithelial cells of well-differentiated t o moderately differentiated prostate carcinoma, whereas in stromal cells th ere were no substantial changes. TrkB IR was absent in; the samples. There was weak p75(LNGFR) IR in normal epithelial cells, which increased in prost ate cancer and to a lesser extent in BPH. Androgen suppression was ineffect ive in reversing TrkA modifications, whereas it caused a decrease in the ex pression of TrkC and 75(LNGFR). Conclusion The abnormal growth of prostatic epithelium is accompanied by in creased TrkA expression and the induction of TrkC expression in epithelial cells, These results suggest that neurotrophins could be involved in the ab normal growth of the human prostate, acting through specific Trk signal-tra nsducing receptors whose expression is regulated by androgens.