Emma E. Moore

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.

Transforming growth factor-β is an autocrine mitogen for a novel androgen-responsive murine prostatic smooth muscle cell line, PSMC1

A prostatic smooth muscle cell line (PSMC1) was established from the dorsolateral prostate of p53 null mice. The cell line is nontumorigenic when inoculated subcutaneously, under the renal capsule or intraprostatically in syngeneic mice. These cells express α–smooth muscle actin (α‐SMA), indicating their smooth muscle origin, and TGF‐β significantly enhances expression of α‐SMA. The cells express both androgen receptor (AR) mRNA and protein, and respond mitogenically to physiological concentrations of androgens. PSMC1 cells produce significant amounts of TGF‐β, which stimulates growth by an autocrine mechanism. Dihydrotestosterone (DHT) increases proliferation of PSMC1 cells by promoting TGF‐β secretion. Considering the significant inhibitory effect of TGF‐β on prostatic epithelial cells and its stimulatory effect on the PSMC1 cells, we postulate that TGF‐β produced by prostatic smooth muscle cells may have a paracrine effect on the prostatic epithelium. We also postulate that TGF‐β may be involved in the etiology of benign prostatic hyperplasia (BPH) by stimulating excessive stromal proliferation. Line PSMC1 is the first reported androgen‐responsive murine smooth muscle cell line. It will be useful for in vivo and in vitro experiments to study the mechanisms of androgen action on prostatic stroma and for delineating the interactions that occur between prostatic smooth muscle and epithelium that may lead to prostatic diseases such as BPH. J. Cell. Physiol. 185:416–424, 2000.

Modulation of calcitonin binding by calcium: differential effects of divalent cations.

Binding of salmon calcitonin to bovine hypothalamic membranes is enhanced about 25% by calcium with a half-maximal effect at 15 mM calcium. In contrast, membranes prepared from a cell line expressing a recombinant human calcitonin receptor show no effect of calcium under similar conditions. The hypothalamic calcitonin receptor solubilized with CHAPS detergent retains an apparent Kd of 0.3 nM for salmon calcitonin; however, binding of calcitonin to the detergent-solubilized receptor complex can be inhibited by divalent cations in order of potency Mn > Ca approximately Sr approximately Mg >> NaCl with Mn and Ca having apparent Kis of 5 mM and 20 mM respectively. Dixon and Scatchard plots of Mn and Ca inhibition of binding to the soluble receptor complex suggest a noncompetitive mechanism of inhibition. Calcium also inhibits calcitonin binding to a detergent-solubilized recombinant human calcitonin receptor. Inhibition of calcitonin binding is observed using two independent methods for determining soluble receptor-hormone complex and inhibition is reversed by EDTA.