Androgen Dependent Variation of Epidermal Growth Factor and Basic Fibroblast Growth Factor in Rat Ventral Prostate

Min, Kyung Joon; Ahn, Hanjong; Lee, Eun Sik; Kim, Hyeon Hoe; Chung, Jae Yong; Park, Won Hee; Lee, Jae Dam; Lee, Chongwook

Abstract

The development, growth, differentiation and function of the prostatic gland are considered to be controlled primarily by androgen. Several hypothesis that the growth factors could mediate the effect of androgen in the prostatic cells and the development of the benign prostatic hyperplasia and malignant prostatic growth may be caused by inappropriate expression of these factors are postulated. In order to define the relationship between androgen and growth factors, we evaluated the changes of the levels of epidermal growth factor( EGF) and basic fibroblast growth factor ( basic FGF) in prostatic regression and regrowth induced by androgen modulation in rat. Male inbred Sprague Dawley rats measuring approximately 250gm in weight were used. Prostatic regression was induced by castration and regrowth induced by androgen replacement. The level of EGF and basic FGF were measured by ELISA method in homogenized rat ventral prostate. It was serially determined that the weight of the ventral prostate and the level of EGF and basic FGF on the 1, 3, 5, 7 and 14th day after castration and androgen replacement. The prostatic weight was measured about 350mg in normal controls and decreased about 50mg on 7th day after castration and there was no change thereafter. After androgen replacement, the prostatic weight increased and reached about 500mg which was larger than normal control on 14th day. Normal rat ventral prostate was composed of tubuloalveolar glands lined by two layer of columnar or cuboidal cells and the small amount of stromal tissue. On 7th day after castration, the epithelial cells were atrophied and sloughed. After androgen replacement, the prostatic glands were regrown and restoration of normal glandular structure was noted. On 14th day after androgen replacement, overgrowth of glands and intraluminal proliferation of epithelial cells. The level of EGF changed similarly with the change of prostatic weight. It decreased to undetectable level on 5th day after castration and increased gradually after androgen replacement. The decrease and increase of EGF level preceded the change of prostatic weight. Also, the level of basic FGF changed similarly with the level of EGF and change of prostatic weight. In conclusion, the levels of EGF, basic FGF and prostatic weight were varied according to androgen depletion or replacement. The decrease and increase of EGF and basic FGF level preceded the change of prostatic weight. These results suggest that EGF and basic FGF influence the prostatic growth by androgen dependent pathway.