The α1-adrenoceptor-mediated human hyperplastic prostate cells proliferation is impaired by EGF receptor inhibition.

Benign prostatic hyperplasia (BPH) is an aging-related and progressive disease linked to an up-regulation of α1-adrenoceptors. The participation of EGF receptors (EGFR) in the GPCRs' signalosome has been described but so far data about the contribution of these receptors to prostatic stromal hyperplasia are scanty. We isolated and cultured vimentin-positive prostate stromal cells obtained from BPH patients. According to intracellular Ca2+ measurements, cell proliferation and Western blotting assays, these cultured hyperplastic stromal cells express functional α1-adrenoceptors and EGFR, and proliferate in response to the α1-adrenoceptor agonist phenylephrine. Interestingly, in these cells the inhibition of EGFR signaling with GM6001, CRM197, AG1478 or PD98059 was associated with full blockage of α1-adrenoceptor-mediated cell proliferation, while cell treatment with each inhibitor alone did not alter basal cell growth. Moreover, the co-incubation of AG1478 (EGFR inhibitor) with α1A/α1D-adrenoceptor antagonists showed no additive inhibitory effect. These findings highlight a putative role of EGFR signaling to α1-adrenoceptor-mediated human prostate hyperplasia, suggesting that the inhibition of this transactivation cascade could be useful to reduce BPH progression.

Pharmacological characterization of N1-(2-methoxyphenyl)-N4-hexylpiperazine as a multi-target antagonist of α1A/α1D-adrenoceptors and 5-HT1A receptors that blocks prostate contraction and cell growth.

Benign prostatic hyperplasia (BPH) is a progressive disease related to the imbalance of cell growth and apoptosis, and it plays a key role in the development of lower urinary tract symptoms (LUTS). The main pharmacological treatment is based on α1A-adrenoceptor blockers, but in several cases monotherapy has failed. Recent studies of prostate pathophysiology have noted the role of α1D-adrenoceptors and 5-HT1A receptors in prostate cell proliferation in addition to the usual role of α1A-adrenoceptors in prostate contraction. N-phenylpiperazine is a scaffold structure that may confer drug affinity for these three receptors. Therefore, the present work aimed to investigate the pharmacological characteristics of N1-(2-methoxyphenyl)-N4-hexylpiperazine (LDT66). Using isometric contraction assays with rat prostate and aorta, LDT66 reduced phenylephrine-induced contractions and showed K B values of 3.4 and 2.2 nM for α1A- and α1D-adrenoceptors, respectively. According to the functional binding assays data, LDT66 showed a high affinity (nanomolar range) for the 5-HT1A receptors, behaving as an antagonist. LDT66 also showed a low affinity (micromolar range) for receptors unrelated to BPH such as α1B-adrenoceptors, α2A-adrenoceptors, muscarinic and 5-HT2A receptors, which is a desirable profile in order to prevent putative side effects. Accordingly, LDT66 (100 µg/kg) showed a marginal hypotensive effect. Using the DU-145 prostate cells, control experiments characterized the α1D-adrenoceptor- and 5-HT1A receptor-mediated cell growth by phenylephrine and 5-HT, respectively. LDT66 (50 nM) prevented both effects similarly. In conclusion, LDT66 is a high-affinity multi-target antagonist of relevant receptors for BPH, and it may be a new starting point for multi-target drug development to treat BPH and LUTS.