Generation of active TGF-β by prostatic cell cocultures using novel basal and luminal prostatic epithelial cell lines

Two prostatic epithelial lines, one of basal origin and one of luminal origin, were established from the dorsolateral prostates of p53 null mice. The cell lines are nontumorigenic when inoculated subcutaneously under the renal capsule or intraprostatically in syngeneic mice. The luminal cell line (PE‐L‐1) expresses cytokeratins 8 and 18 and the basal cell line (PE‐B‐1) expresses cytokeratins 5 and 14. The basal cells require serum for growth, whereas the luminal cells grow only in serum‐free medium. Both cell lines require the presence of growth factors for optimal growth in culture, with EGF and FGF‐2 having the greatest effect on the growth rate. Both lines express androgen receptor (AR) mRNA and protein. Androgen stimulates growth of the basal cell line, indicating that the ARs are functional, whereas growth of the luminal cells is unaffected by androgens. The luminal line is significantly inhibited by exogenous TGF‐β and produces low levels of endogenous TGF‐β. In contrast, the basal cell line produces significant amounts of TGF‐β and its growth is not influenced by this cytokine. Coculture of luminal cells with prostatic smooth muscle cells results in the generation of increased levels of biologically active TGF‐β, indicating a paracrine mechanism of TGF‐β activation that may be involved in the maintenance of normal prostatic function. To our knowledge this is the first report describing both basal and luminal prostatic cell lines from a single inbred animal species and the first indication that prostatic epithelial and stromal cells interact to generate the biologically active form of TGF‐β. These lines will provide an important model for determining basal/luminal interactions in both in vitro and in vivo assays. J. Cell. Physiol. 184:70–79, 2000. © 2000 Wiley‐Liss, Inc.