(17.ALPHA.,20E)-17,20-[(1-Methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic Acid Methyl Ester (YK11) Is a Partial Agonist of the Androgen Receptor

Abstract

The androgen receptor (AR) is a member of the nuclear receptor (NR) superfamily of ligand-dependent transactivation factors. Androgens such as testosterone and 5-a-dihydrotestosterone (DHT) act as agonists of AR. AR mediates various biological effects such as the development of male reproductive tissues, sexual development, and spermatogenesis. [1][2][3][4] Since androgen declining with age contributes to age-related bone and muscle loss and increase in fat mass, 5) the anabolic effect of androgen is attractive for the maintenance of health. Furthermore, it is known that AR is involved in androgen-dependent prostate cancer growth. Thus, antagonists of AR (flutamide, bicalutamide, and nilutamide) are used in anti-androgen therapy for prostate cancer. 8,9) AR mediates the expression of androgen-regulated genes, as represented by prostate specific antigen (PSA) [10][11][12] and FK506-binding protein 51 (FKBP51). [13][14][15] In the absence of a ligand, AR is localized in the cytoplasm, where it forms complexes with chaperones. Upon ligand binding, AR translocates into the nucleus. Following nuclear translocation, AR binds to androgen responsive elements (ARE) in the promoter regions of its target genes as a homodimer. Generally, the transcriptional activity of nuclear receptors is modulated by their interaction with cofactors such as coactivators and corepressors. [16][17][18][19] The type of ligand that binds to the receptor determines which type of cofactor is chosen. In the case of agonists, AR interacts with coactivators dominantly over corepressors, and vice versa in the case of antagonists.Unlike other nuclear receptors, AR AF2 demonstrates weak transcriptional activity. However, ligand-dependent interaction between NTD and LBD/AF2 (which is termed as the N/C interaction) endows AR with synergistic transactivation potential. [20][21][22][23] Thus, the N/C interaction is important for the ligand-dependent transactivation potential of AR.Synthetic AR ligands are useful for treatment of prostate cancer and age-related diseases such as osteopenia and sarcopenia. Previously, we prepared novel synthetic steroids.24) In our preliminary screening for novel AR ligands, a steroid compound, (17a,20E)-17,20-[(1-methoxyethylidene) bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11), behaved apparently as a partial agonist of AR in an ARE-luciferase reporter assay (unpublished data). We were interested in this partial agonistic nature of YK11. In this report, we will show that YK11 blocks the N/C-interaction required for the full-agonistic function of wild-type AR, inducing selective AR-target genes owing to the constitutive transactivation potential of AF-1 subdomain in endogenous AR-expressing MDA-MB 453 cells. MATERIALS AND METHODS ChemicalsThe compounds tested in our preliminary screening for novel AR ligands were prepared by previously

Mass spectrometric characterization of the selective androgen receptor modulator (SARM) YK‐11 for doping control purposes

“…Reference material of YK‐11 was synthesized according to published methods and its structure was confirmed by 1 H and 13 C NMR. In agreement with literature data, the following chemical shifts were identified for the major diastereomer: 1 H‐NMR (CD 3 CN) major diastereomer [δ]: 0.67–0.77 (1H, m), 0.91–1.02 (1H, m), 0.98 (3H, s), 1.2–1.62 (7H, m), 1.6 (3H, s), 1.78–1.89 (3H, m), 2.1–2.3 (5H, m), 2.4–2.46 (1H, m), 3.1 (3H, s), 3.57 (3H, s), 5.59 (1H, s), 5.71 (1H, s); 13 C‐NMR (CD 3 CN) major diastereomer [δ]: 14.9, 24.7, 24.8, 26.5, 27.1, 31.7, 32.6, 34.0, 35.7, 36.9, 41.1, 42.7, 49.0, 49.7, 50.5, 50.5, 51.6, 93.9, 98.8, 121.5, 124.5, 167.1, 167.8, 170.3, 200.0. Corresponding spectra are illustrated in Supplementary Fig.…”

“…YK‐11 and its deuterated analogs were synthesized in accordance with published protocols . The introduction of deuterium atoms was accomplished by different modifications of the synthesis: using methanol‐d 4 as reagent led to bis‐trideuteromethyl YK‐11 (Fig.…”

“…YK-11 and its deuterated analogs were synthesized in accordance with published protocols. [23,24] The introduction of deuterium atoms was accomplished by different modifications of the synthesis: using methanol-d 4 as reagent led to bis-trideuteromethyl YK-11 ( Fig. 1, 2), H/D exchange of the mobile protons at C-2, C-4, C-6, and C-10 of norethisterone under alkaline conditions prior to acetylation and subsequent cyclization-carbonylation of the propargylic ester function yielded 2 H 6 -YK-11 ( Fig.…”

“…Its structural analog, comprising of a 3-oxo-pregna-4,20-diene nucleus, was described in 2006, [23] and the partial agonistic properties of YK-11 at the androgen receptor were reported in the scientific literature in 2011. [24] Its mode of action was reported to involve the induction of follistatin expression, [25] and, whilst clinical trial data are not yet available, YK-11 has become available via Internet-based suppliers. In order to facilitate the control of the drug candidate's potential misuse in professional sport, expanding the existing analytical approaches in doping controls is required.…”

Selective Androgen Receptor Modulator, YK11, Regulates Myogenic Differentiation of C2C12 Myoblasts by Follistatin Expression

“…Full activation of AR requires physical interaction between the NTD/AF1 and LBD/ AF2 (known as the N/C interaction). [18][19][20][21] Follistatin (Fst) is essential for muscle fiber formation and growth. It is an extracellular protein that acts as an inhibitory binding partner of activins and selected transforming growth factor β (TGF-β) family members.…”