Acylthiourea, Acylurea, and Acylguanidine Derivatives with Potent Hedgehog Inhibiting Activity

Abstract

The Smoothened (Smo) receptor is the major transducer of the Hedgehog (Hh) signaling pathway. On the basis of the structure of the acylthiourea Smo antagonist (MRT-10), a number of different series of analogous compounds were prepared by ligand-based structural optimization. The acylthioureas, originally identified as actives, were converted into the corresponding acylureas or acylguanidines. In each series, similar structural trends delivered potent compounds with IC(50) values in the nanomolar range with respect to the inhibition of the Hh signaling pathway in various cell-based assays and of BODIPY-cyclopamine binding to human Smo. The similarity of their biological activities, in spite of discrete structural differences, may reveal the existence of hydrogen-bonding interactions between the ligands and the receptor pocket. Biological potency of compounds 61, 72, and 86 (MRT-83) were comparable to those of the clinical candidate GDC-0449. These findings suggest that these original molecules will help delineate Smo and Hh functions and can be developed as potential anticancer agents.

Discovery, Molecular and Pharmacological Characterization of GSA-10, a Novel Small-Molecule Positive Modulator of Smoothened

“…We first tested these compounds at a large range of doses in NIH3T3 cells stably transfected with a Gli-dependent firefly luciferase reporter (Taipale et al, 2000). This mouse embryonic fibroblast cell line has been widely used for measuring Hh signaling activity through Smo (Solinas et al, 2012). We observed that, as expected (Masdeu et al, 2006), SAG potently stimulated Hh reporter gene transcription with an EC 50 of ∼0.15 mM, whereas GSA-10 displayed no stimulatory effect, even at 10 mM (Fig.…”

“…The concentration of SAG and GSA-10 used in these experiments was near their respective EC 50 . The potent Smo antagonist MRT-83 (Roudaut et al, 2011;Solinas et al, 2012) displayed a similar potency to block Virtual Screening-Based Discovery of GSA-10 GSA-10 (1 mM) and SAG (0.1 mM) response (IC 50 , ∼38 and 11 nM, respectively) (Fig. 7, B and C).…”

“…Recently, we identified and developed a series of thioureas, ureas, and guanidines as novel potent Smo antagonists with use of a pharmacophorebased virtual screening strategy (Manetti et al, 2010;Roudaut et al, 2011;Solinas et al, 2012). We reasoned that we could exploit this strategy to identify novel Smo agonists starting from purmorphamine, SAG, and its derivatives as reference Smo agonists (Fig.…”

“…Potential Smo modulators identified from virtual screening were purchased from Asinex. MRT-83, CUR61414, and SAG were synthesized as described elsewhere (Solinas et al, 2012). M25 (2-ethyl-N-((1-(2-methoxyphenyl)-1H-indazol-5-yl)methyl) butanamide) was prepared in accordance with a general procedure reported for analogous 1H-indazoles (Dessole et al, 2009 Synthesis of GSA-10.…”

A new ferrocene–anthracene dyad for dual-signaling sensing of Cu(II) and Hg(II)

“…In the 1 H NMR spectrum, the signal of thiourea NH proton adjacent the phenyl ring of 1 and 2 is located in the far down field (11.67 and 12.91 ppm in CD 3 Cl solution), which can be attributed to the strong intramolecular hydrogen bond formation in 1 and 2 (see below). Strong intramolecular hydrogen bond is often observed in acylthiourea ligands [56].…”