DIFFERENTIAL EXPRESSION OF ACIDIC AND BASIC FIBROBLAST GROWTH-FACTORSIN BENIGN PROSTATIC HYPERPLASIA IDENTIFIED BY IMMUNOHISTOCHEMISTRY

Objectives To detect the expression and to determine the relative cell ular locations of the two peptide growth factors, acidic fibroblast gr owth factor (a-FGF) and basic (b)-FGF in tissues from human benign pro static hyperplasia (BPH). Materials and methods A series of 50 sequent ial and unselected cases of human BPH tissues, obtained after transure thral prostatectomy, was examined. Adjacent sections of formalin-fixed and paraffun wax-embedded tissues were stained immunohistochemically for expression of a-FGF and b-FGF using well-characterized and commerc ially available antibodies. The stained tissue sections were assessed for the cellular distribution of immunohistochemical products and anal ysed according to the relative intensity of staining as well as the sp atial relationships of positively stained cells. Results Acidic-FGF wa s weakly expressed with a pancytoplasmic distribution within luminal g landular epithelial cells in regions of prostatic intra-epithelial neo plasia (both PIN I and II) but not by non-dysplastic normal or hyperpl astic tissues. No expression of a-FGF was detected in basal epithelial cells or in the stromal compartment of any tissue examined. In contra st, b-FGF was strongly expressed within the cytoplasm of all basal epi thelial cells, but not by luminal epithelial cells, in morphologically normal regions of all cases examined. Basal expression of b-FGF was d iminished, or absent, in regions of mild epithelial dysplasia, particu larly those strongly expressing a-FGF. Extensive nuclear and cytoplasm ic expression of b-FGF occurred predominantly in smooth muscle-type st romal cells but not in all types of stromal cells. Conclusions This st udy confirmed both a differential and a reciprocal expression of a-and b-FGF in non-dysplastic prostatic hyperplasia and in mildly dysplasti c regions of prostatic tissues. While only small amounts of a-FGF were expressed in BPH, exclusively in the luminal epithelial compartment, its consistent appearance in PIN I and II suggests that it might contr ibute to the early stages of PIN. Conversely, b-FGF may be an importan t mediator of stromal-epithelial interaction during the pathogenesis o f BPH. These results provide new information about the relative expres sion of these growth factors, particularly in the architectural relati onships between different cell-types within normal and non-malignant p rostatic tissues.