Inhibition of human prostate smooth muscle contraction by the inhibitors of protein kinase C, GF109203X, and Go6983

Abstract

Introduction: Prostate smooth muscle contraction is promoted by receptor-induced activation of intracellular signaling pathways. The presumed involvement in etiology and medical treatment of lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) imparts a high clinical relevance to prostate smooth muscle contraction, which is contrasted by incomplete understanding at the molecular level. Involvement of protein kinase C (PKC) has been commonly assumed, but available studies were limited to nonhuman prostate smooth muscle or cell cultures.Here, we examined the effects of the PKC inhibitors Go6983 and GF109203x on contractions of human prostate tissues.Methods: Prostate tissues were obtained from radical prostatectomy. Contractions were induced by electric field stimulation (EFS), α 1 -adrenergic agonists (noradrenaline, phenylephrine, methoxamine), thromboxane A 2 analog U46619, endothelin-1, or calcium chloride in an organ bath.Results: GF109203X (500 nM) and Go6983 (300 nM) reduced EFS-, noradrenaline-, phenylephrine-, methoxamine-, and U46619-induced contractions of human prostate tissues, with maximum inhibitions approaching up to 55%. Using concentrations of 3 µM, GF109203X and Go6983 inhibited EFS-and noradrenaline-induced contractions, with similar effect sizes as 500 and 300 nM, respectively. Endothelin-1induced contractions were not inhibited by GF109203X, and to neglectable extent by Go6983. After depolarization in calcium-free solution, calcium chloride-induced concentration-dependent contractions, which were inhibited by GF109203X and Go6983.Conclusions: GF109203X and Go6983 inhibit neurogenic, α 1 -adrenergic, and thromboxane A 2 -induced smooth muscle contractions in the human prostate, suggesting a role of PKC for human prostate smooth muscle contraction. The inhibition may by be imparted by inhibition of calcium sensitivity.

Isoform‐independent promotion of contractility and proliferation, and suppression of survival by with no lysine/K kinases in prostate stromal cells

“…Contractions in this assay are timedependent, starting around one hour after seeding of cells to matrix plugs, and continuously increase on a time scale of hours, while agonist-induced contractions in vivo and of tissue strips in an organ bath occur within seconds to minutes. 47 Consequently, the two types of contraction may or may not involve the same type of signaling. Obviously, however, both types of contraction are regulated by WNKs, as both were susceptible to WNK463, at least partly.…”

“…Silencing of each WNK isoform in fact suggested roles of each isoform for contraction of stromal cells in our assays. Contractions in this assay are time‐dependent, starting around one hour after seeding of cells to matrix plugs, and continuously increase on a time scale of hours, while agonist‐induced contractions in vivo and of tissue strips in an organ bath occur within seconds to minutes 47 . Consequently, the two types of contraction may or may not involve the same type of signaling.…”

Inhibition of α1-Adrenergic, Non-Adrenergic and Neurogenic Human Prostate Smooth Muscle Contraction and of Stromal Cell Growth by the Isoflavones Genistein and Daidzein

“…Subsequently, contractions induced by 80 mM KCl were assessed by the addition of a 2 M stock solution to assess highmolar KCl-induced contractions as a measure of smooth muscle content and condition and as a later reference for agonist-induced and neurogenic contractions. Highmolar KCl results in biphasic responses, including a phasic contraction reaching a peak within a few minutes after the addition of KCl, which was used for normalization, as described below, followed by a decline to a tonic, stable contraction [ 30 ]. After the peak of the phasic contraction was obtained and the tension started to decline to the tonic phase, the chambers were washed by replacing the Krebs–Henseleit solution three times, resulting in a stable resting tone close to the first baseline before KCl.…”

“…For calculation, the maximum contraction level at a given agonist concentration or given frequency was assessed, regardless of the pattern of contraction. In fact, contraction patterns in our samples differed between α 1 -adrenergic and non-adrenergic agonists and between tissues and patients [ 30 ]. In either case, however, the next higher concentration in the concentration–response curves was applied as soon as the plateau contraction was attained and no further substantial increase was expected.…”