REGULATION OF KERATINOCYTE GROWTH FACTOR RECEPTOR AND ANDROGEN RECEPTOR IN EPITHELIAL CELLS OF THE HUMAN PROSTATE

Abstract

Stromal-epithelial interactions of growth factors and the androgen receptor may have implications for the pathophysiology of benign and neoplastic transformation of the human adult prostate. We investigated a possible interaction of keratinocyte growth factor with its receptor as well as with the androgen receptor signaling pathway in human prostatic epithelial cells. Human prostatic epithelial cells were obtained from explant primary culture, established in DU145 cell conditioned medium and maintained in keratinocyte serum-free medium with supplements. Epithelial cells were characterized by light and electron microscopy, and immunocytochemical study using epithelial and mesenchymal markers. Androgen receptor, keratinocyte growth factor receptor and keratinocyte growth factor messenger RNA expression was measured by polymerase chain reaction (PCR). The response to 0.01 to 10 nM. dihydrotestosterone, 10 microM. flutamide and 1 to 1,000 ng./ml. keratinocyte growth factor was tested by [3H] thymidine assay. The difference in keratinocyte growth factor receptor and androgen receptor gene expression after treatment with and without keratinocyte growth factor and flutamide were determined by quantitative multiplex PCR and quantitated using densitometry analysis. Immunocytochemical and electron microscopy characterization revealed typical epithelial differentiation. PCR showed keratinocyte growth factor receptor and androgen receptor expression in epithelial cultured cells but no keratinocyte growth factor expression. Epithelial cells showed a significant time and dose dependent stimulation of cell proliferation with keratinocyte growth factor and dihydrotestosterone (p <0.05). When combined with the anti-androgen flutamide the effect of 100 ng./ml. keratinocyte growth factor was significantly decreased (p <0.05). At 100 ng./ml. keratinocyte growth factor quantitative multiplex PCR revealed stimulated keratinocyte growth factor receptor and androgen receptor messenger RNA expression. These results show that keratinocyte growth factor up-regulates the keratinocyte growth factor and androgen receptors in the absence of androgen. Thus, the androgen signaling pathway may be activated by growth factors such as keratinocyte growth factor in an androgen deficient environment.