Effects of alpha1-adrenoceptor antagonists on cultured prostatic smooth muscle cells.

Background: alpha1-adrenoceptor (alpha1-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 alpha1-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 alpha1-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. alpha1-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 microM) 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 alpha1-AR antagonists on cell contraction, growth, and differentiation can be investigated. The results indicate that in addition to inhibition of cell contraction, alpha1-AR antagonists have the potential to induce apoptosis.