New Multi-target Antagonists of  1A-,  1D-Adrenoceptors and 5-HT1A Receptors Reduce Human Hyperplastic Prostate Cell Growth and the Increase of Intraurethral Pressure

Abstract

Benign prostatic hyperplasia (BPH) is characterized by stromal cell proliferation and contraction of the periurethral smooth muscle, causing lower urinary tract symptoms. Current BPH treatment, based on monotherapy with a 1A -adrenoceptor antagonists, is helpful for many patients, but insufficient for others, and recent reports suggest that stimulation of a 1D -adrenoceptors and 5-hydroxytryptamine (serotonin) (5-HT) 1A receptors contributes to cell proliferation. In this study, we investigated the potential of three N-phenylpiperazine derivatives (LDT3, LDT5, and LDT8) as multi-target antagonists of BPH-associated receptors. The affinity and efficacy of LDTs were estimated in isometric contraction and competition-binding assays using tissues (prostate and aorta) and brain membrane samples enriched in specific on-or off-target receptors. LDTs' potency was estimated in intracellular Ca 21 elevation assays using cells overexpressing human a 1 -adrenoceptor subtypes. The antiproliferative effect of LDTs on prostate cells from BPH patients was evaluated by viable cell counting and 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assays. We also determined LDTs' effects on rat intraurethral and arterial pressure. LDT3 and LDT5 are potent antagonists of a 1A -, a 1D -adrenoceptors, and 5-HT 1A receptors (K i values in the nanomolar range), and fully inhibited phenylephrine-and 5-HT-induced proliferation of BPH cells. In vivo, LDT3 and LDT5 fully blocked the increase of intraurethral pressure (IUP) induced by phenylephrine at doses (ED 50 of 0.15 and 0.09 mg.kg 21 , respectively) without effect on basal mean blood pressure. LDT3 and LDT5 are multi-target antagonists of key receptors in BPH, and are capable of triggering both prostate muscle relaxation and human hyperplastic prostate cell growth inhibition in vitro. Thus, LDT3 and LDT5 represent potential new lead compounds for BPH treatment.

ADME studies and preliminary safety pharmacology of LDT5, a lead compound for the treatment of benign prostatic hyperplasia

“…In our previous paper (7), we detailed the in vitro and in vivo pharmacodynamics properties of LDT5 that support our hypothesis of a multi-target antagonism for a dual effect in BPH treatment. Here, we report data addressing the drug-likeness and safety of our elected compound.…”

“…The concentration of LDT5 used in these assays (0.5 µM) was chosen according to the typically low concentrations (1–5 µM) of test compound used for incubation to ensure the linearity of enzymatic reaction, but higher than its putative clinically relevant concentration since it is 250–2500 times higher than the affinity for its main target receptors (7). From these data (Figure 2), we can conclude that LDT5 is stable in human liver microsomes (half-life >30 min; intrinsic clearance <0.6 mL·min -1 ·g liver -1 ) and hepatocytes (half-life 120 min; intrinsic clearance <0.2; 0.22 mL·min -1 ·g liver -1 ).…”

“…LDT5 (1-(2-methoxyphenyl)-4-[2-(3,4-dimethoxyphenyl)ethyl]piperazine monohydrochloride) was synthesized and characterized by spectroscopy as previously described (7). Figure 1 provides the 2-D structure of LDT5 in its base form.…”

“…First, we showed that the N 1-(2-methoxyphenyl)- N 4-piperazine moiety confers affinity for α 1A -, α 1D -adrenoceptors and 5-HT 1A receptors (6). Then, we reported that one of the derivatives, LDT5, was a multi-target compound designed to exert both prostatic relaxation and antiproliferative actions in BPH through action at three different receptor targets: antagonism at α 1A -adrenoceptor providing mechanism of action (MOA) for treating LUTS while antagonism at the α 1D -adrenoceptor and 5-HT 1A receptor would provide MOA for preventing human prostatic stromal hyperplasia (7). As a result, such compound would have potential clinical use either as monotherapy in first stages of BPH or after treatment, to shrink the prostate (e.g., with a 5-ARI).…”

Does pharmacological activation of 5-HT1A receptors improve urine flow rate in female rats?

“…However, we speculated that most effects of 8-OH-DPAT and WAY-100635 are exerted on the central level rather than on the peripheral level because the intrathecal or intracerebroventricular injections exert excitatory or inhibitory effects, respectively, on micturition reflex activity (17,19,21,37). However, a direct effect of the 5-HT 1A receptor on urethral smooth muscles cannot be excluded because a recent study reported that a 5-HT 1A receptor agonist can modulate the isometric contraction in isolated urethral smooth muscle strips prepared from rats (24). Nevertheless, verification of this assumption is warranted in future studies.…”