Lysophosphatidic acid receptor agonism: discovery of potent non-lipid benzofuran ethanolamine structures.

Lysophosphatidic acid (LPA) is the natural ligand for two phylogenetically distinct families of receptors (LPA1-3, LPA4-6), whose pathways control a variety of physiological and pathophysiological responses. Identifying the benefit of balanced activation/repression of LPA receptors has always been a challenge due to the high lability of LPA together with the limited availability of selective and/or stable agonists. In the present study, we document the discovery of small benzofuran ethanolamine derivatives (called CpX and CpY) behaving as LPA1-3 agonists. Initially found as rabbit urethra contracting agents, their elusive receptors were identified from [35S]GTPγS-binding and β-arrestin2 recruitment investigations, then confirmed by [3H]CpX binding studies (urethra, hLPA1-2 membranes). Both compounds induced a calcium response in hLPA1-3 cells within a range of 0.4 to 1.5-log lower potency, as compared to LPA. The contractions of rabbit urethra strips induced by these compounds perfectly matched binding affinities with values reaching the 2-digit nM level. The antagonist, KI16425, dose-dependently antagonized CpX-induced contractions in agreement with its affinity profile (LPA1≥LPA3>>LPA2). The most potent agonist, CpY, doubled intra-urethral pressure in anesthetized female rats at 3 µg/kg i.v. Alternatively, CpX was shown to inhibit human preadipocyte differentiation, a process totally reversed by KI16425. Together with original molecular docking data, these findings clearly established these molecules as potent agonists of LPA1-3 and consolidated the pivotal role of LPA1 in urethra/prostate contraction as well as in fat cell development. The discovery of these unique and less labile LPA1-3 agonists, would offer new avenues to investigate the roles of LPAR. SIGNIFICANCE STATEMENT: We report the identification of benzofuran ethanolamine derivatives behaving as potent selective non-lipid LPA1-3 agonists and shown to alter urethra muscle contraction or pre-adipocyte differentiation. Unique at this level of potency, selectivity and especially stability compared to lysophosphatidic acid, they represent more appropriate tools for investigating the physiological roles of lysophosphatidic acid receptors and starting point for optimization of drug candidates for therapeutic applications. The American Society for Pharmacology and Experimental Therapeutics.