OVEREXPRESSION OF HUMAN EPIDERMAL GROWTH-FACTOR RECEPTOR AND C-ERBB-2BY NEUROENDOCRINE CELLS IN NORMAL PROSTATIC TISSUE

Objective. It has been suggested that prostatic neuroendocrine (NE) ce lls play an important role in the growth and differentiation of the pr ostate by secreting various neuropeptides and serotonin. However, the mechanism by which NE cells themselves are regulated is virtually unkn own. In the present study we evaluated the expression of the human epi dermal growth factor receptor (EGFR) family (HER) in prostatic NE cell s. Methods. Formalin-fixed, paraffin-embedded tissue sections from twe nty radical prostatectomy specimens were immunostained with validated rabbit polyclonal antibodies raised against human EGFR and c-erbB-2, u sing the streptavidin-peroxidase enzyme conjugate method. Results. A s trong immunoreactivity was observed with both antibodies in the cytoso l of a few epithelial cells. These cells frequently had a dendritic ap pearance and were located in the acini and ducts. The EGFR-positive ce lls were predominant in most cases. Double immunostaining revealed the colocalization of both antigens with chromogranin A, a polypeptide th at is expressed by most NE cells. Moreover, EGFR and c-erbB-2 appeared to be colocalized as well as independently expressed by different sub populations of NE cells. Conclusions. The results suggest that prostat ic NE cells might be regulated by the HER protein family, probably, in a ligand-specific fashion. This is the first report identifying a pot ential pathway regulating prostatic NE cells.