Epidermal growth factor in the rat prostate: production, tissue content and molecular forms in the different prostatic lobes.

BACKGROUND

Epidermal growth factor (EGF) induces proliferation in prostate epithelial and stromal cells in primary culture. This investigation was set up to characterize the time and spatial expression of EGF in the rat prostate.

METHODS

The expression of EGF was characterized in the distinct lobes of the rat prostate by means of ELISA, gel filtration, immunohistochemistry, and in situ hybridization.

RESULTS

Local synthesis of EGF by the luminal epithelium was demonstrated by in situ hybridization in the dorsal lobe only. This lobe contained the major part of the prostatic EGF with a sixfold higher concentration than measured in the lateral lobe, and 300-fold higher than in the ventral lobe. Rat prostatic EGF was found to consist of at least two high-molecular-weight forms, as well as a 6-kDa form. The high-molecular-weight forms made up approximately 40% of the EGF measured in the dorsal rat prostate. At 8-12 weeks of age, the concentration of EGF in the dorsal lobe was doubled, with no further increase up to 16 weeks.

CONCLUSIONS

We report a 300-fold difference in the lobar content of EGF in the rat prostate, and a doubling of the concentration at 8-12 weeks of age.