Effects of ?1-adrenoceptor antagonists on cultured prostatic smooth muscle cells

Abstract

BACKGROUND α1‐adrenoceptor (α1‐AR) antagonists, used to relieve the lower tract urinary symptoms (LUTS) in benign prostate hyperplasia (BPH) patients, are thought to act in inhibiting the contraction of stromal smooth muscle. An attempt was made using new technology to visualize and quantify the effect of α1‐AR antagonists in a cell culture model of prostatic smooth muscle cells (SMC). METHODS Prostatic smooth muscle cells cultured from human prostate tissue were treated with α1‐AR agonists and antagonists. The effects on cell growth, cell contraction, differentiation status, and apoptosis were determined by means of an MTT cell viability assay, time‐lapse video microscopy, RT‐PCR analysis, and FACS analysis of annexin V/propidium iodide‐stained cells, respectively. RESULTS Prostatic smooth muscle cells derived from prostate tissue expressed SMC‐specific markers. They showed spontaneous contractions, and phenylephrine increased the percentage of contracting cells by 3‐fold. α1‐AR antagonists inhibited spontaneous as well as phenylephrine‐induced contractions. Long‐term treatment with doxazosin induced differentiation tended towards a contractile phenotype, as indicated by an increase of the ratio of smooth muscle heavy chain myosin subtypes SM2/SM1. There was, however, no effect on cell growth. High concentrations of antagonist (100 μM) induced apoptosis in about 80% of the treated SMC. This effect was not cell‐type‐specific and was also seen in skin fibroblasts and immortalized prostate epithelial cells. CONCLUSION In an easy‐to‐handle cell culture model of prostatic smooth muscle cells, the effects of α1‐AR antagonists on cell contraction, growth, and differentiation can be investigated. The results indicate that in addition to inhibition of cell contraction, α1‐AR antagonists have the potential to induce apoptosis. Prostate Supplement 9:34–41, 2000. © 2000 Wiley‐Liss, Inc.

Androgens regulate adenylate cyclase activity and intracellular calcium in stromal cells derived from human prostate

“…Spontaneous elevations of calcium and spontaneous contractions have been shown previously in HCPSC 15,16. Although Boesch et al 16 report that the number of cells exhibiting spontaneous contractions is significantly elevated by the α‐adrenoceptor agonist phenylephrine, in our studies the non‐selective adrenoceptor agonist, noradrenaline, had no effect on peaking activity.…”

Protein kinase G‐induced activation of KATP channels reduces contractility of human prostate tissue

“…Studies from this and other laboratories have shown that human cultured prostatic stromal cells make a reasonably good model of human prostate contractility since they respond to phenylephrine with a 1 -adrenoceptor antagonist-sensitive contractions [23][24][25]. These contractions and corresponding elevations of intracellular Ca 2þ are also sensitive to nifedipine [24].…”

α1‐Adrenoceptor effects mediated by protein kinase C α in human cultured prostatic stromal cells

“…Several studies have shown that freshly dissociated prostatic myocytes and cultured prostatic stromal cells exhibit some of the same characteristics as preparations of intact prostate. Specifically, they respond to phenylephrine with contractions that are blocked by α 1 ‐adrenoceptor antagonists (Boesch et al ., 2000; Corvin et al ., 1998; Eckert et al ., 1995), and also with an increase in [Ca 2+ ] i (Eckert et al ., 1995). Previous work from our laboratory has implicated PKC activation in the phorbol ester‐mediated contractility of HCPSC (Haynes et al ., 2002), however the role of PKC in the α 1 ‐adrenoceptor‐mediated contractility of HCPSC remains equivocal (Eckert et al ., 1995; Marshall et al ., 1999).…”