Four sets of diastereomeric C9-alkenyl 5-phenylmorphans, varying in the length of the C9-alkenyl chain, were designed to examine the effect of these spatially distinct ligands on opioid receptors. Functional activity was obtained by forskolin-induced cAMP accumulation assays and several compounds were examined in the [35S]GTPgS assay and in an assay for respiratory depression. In each of the four sets, similarities and differences were observed dependent on the length of their C9-alkenyl chain and, most importantly, their stereochemistry. Three MOR antagonists were found to be as or more potent than naltrexone and, unlike naltrexone, none had MOR, KOR, or DOR agonist activity. Several potent MOR full agonists were obtained, and, of particular interest partial agonists were found that exhibited less respiratory depression than that caused by morphine. The effect of stereochemistry and the length of the C9-alkenyl chain was also explored using molecular modeling. The MOR antagonists were found to interact with the inactive (4DKL) MOR crystal structures and agonists were found to interact with the active (6DDF) MOR crystal structures. The comparison of their binding modes at the mouse MOR was used to gain insight into the structural basis for their stereochemically induced pharmacological differences.
Abstract Ewing Sarcoma, a devastating malignancy affecting mainly pediatric and young adult populations, is characterized by the aberrant activity of the oncogenic EWS-FLI1 transcription. However, the development of treatments against EWS-FLI1 is lacking. Mithramycin analogues, exhibiting specificity towards EWS-FLI1, have been posited as a groundbreaking approach in drug discovery for the treatment of Ewing Sarcoma. A phase I/II trial and pharmacokinetic (PK) study in Ewing sarcoma patients demonstrated that mithramycin (MTM) had poor PK and dose-limiting hepatic and hematologic toxicities at subtherapeutic concentrations. Here we present a novel MTM analogue with significantly improved PK and a wider therapeutic window. MTMSA-Trp was prepared by chemical conversion of MTM to the MTMSA analogue and the subsequent conjugation of a tryptophan amino acid. The bulky amino acid substitution on the 3-side chain of the molecule appears to shift the ionization properties of the two hydroxy groups on the tricyclic core and to increase protein binding, both of which appear to lead to significantly improved pharmacokinetics. Further, based on crystallographic evaluation, the bulky hydrophobic substitution on the 3-side chain protrudes outside the DNA helix and interacts with bound FLI1. Luciferase reporter and FRET assays demonstrate a dose-dependent effect of MTMSA-Trp on the attenuation of EWS-FLI1 transcription and DNA binding, and based on CETSA evidence, there is physical interaction between MTMSA-Trp and EWS-FLI1. The cytotoxicity of MTMSA-Trp is in the order of low nM across several cell lines expressing EWS-ETS fusions, and the compound disrupts the expression of positively regulated proteins (NR0B1, ID2) and induces expression of negatively regulated ones (CD44, LOX). EWS-FLI1 modulation persists longer when cells are exposed to the GI90 concentration for a short time compared to the GI50 for longer times, suggesting that daily dosing or continuous exposure is not required. MTMSA-Trp has improved PK in athymic nu/nu mice with a greater than 10-fold reduction in clearance and significantly reduced partition in the liver as compared to MTM. Initial efficacy studies in TC32 Ewing Sarcoma cells demonstrated tumor regression and improved survival at the maximum tolerated dose (MTD) and at 2/3 of the MTD on a daily x 5 intravenous bolus injection. Significantly, a more protracted dosing schedule which allowed for higher doses every third day for six doses led to an impressive reduction of tumors whose initial size was above 15 mm in one diameter (i.e., 1200-1600 mm3). Our studies with MTMSA-Trp demonstrate that improving the pharmacologic properties of mithramycin may lead to the development of an EWS-FLI1 inhibitor. Ongoing studies are evaluating the efficacy of MTMSA-Trp in additional Ewing models, and future work will focus on pre-IND studies. Citation Format: Markos Leggas, Kumar K Niloy, Rajesh Yetijaram, Jamie Horn, Yasuda Kazuto, Thomas Prisinzano, Jon S Thorson, Oleg Tsoikov, Jurgen Rohr. Targeting EWS-FLI1 with mithramycin analogues for Ewing sarcoma treatment [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B150.
A high-throughput, cell-based screen was used to identify chemotypes as inhibitors for human respiratory syncytial virus (hRSV). Optimization of a sulfonylpyrrolidine scaffold resulted in compound 5o that inhibited a virus-induced cytopathic effect in the entry stage of infection (EC₅₀ = 2.3 ± 0.8 μM) with marginal cytotoxicity (CC₅₀ = 30.9 ± 1.1 μM) and reduced viral titer by 100-fold. Compared to ribavirin, sulfonylpyrrolidine 5o demonstrated an improved in vitro potency and selectivity index.
The synthesis of stereochemically pure oximes, amines, saturated and unsaturated cyanomethyl compounds, and methylaminomethyl compounds at the C9 position in 3-hydroxy-
Abstract Previous studies established that Tyr‐ D ‐Ala‐Gly‐N‐Me‐Phe‐Gly‐ol (DAMGO) and (2 S ,4a R ,6a R ,7 R ,9 S ,10a S ,10b R )‐9‐(Benzoyloxy)‐2‐(3‐furanyl)dodecahydro‐6a,10b‐dimethyl‐4,10‐dioxo‐2 H ‐naphtho‐[2,1‐ c ]pyran‐7‐carboxylic acid methyl ester (herkinorin) are fully efficacious μ ‐agonists. Herkinorin (HERK), unlike DAMGO, does not recruit β‐arrestin and promote μ ‐receptor internalization, even in cells that over express β‐arrestin. We hypothesized that chronic HERK and DAMGO treatment will differentially affect cellular markers of tolerance and dependence. CHO cells expressing the cloned human μ ‐receptor were treated for 20 h with 10 μM DAMGO, HERK, morphine, or medium. Both DAMGO and HERK acted as full agonists in the [ 35 S]GTP‐γ‐S binding assay with E MAX values of 230% and EC 50 values of 12.8 and 92.5 nM, respectively. In the cAMP assay, DAMGO and HERK had similar E MAX values of ∼80% and EC 50 values of 3.23 and 48.7 nM, respectively. Chronic exposure to both drugs produced moderate tolerance to both drugs (∼2 to 5 fold) in the [ 35 S]GTP‐γ‐S binding assay. In the cAMP assay, chronic DAMGO produced tolerance to both drugs (∼3 to 4 fold). Chronic HERK eliminated the ability of either drug to inhibit forskolin‐stimulated cAMP accumulation. Chronic DAMGO increased, and chronic HERK decreased, forskolin‐stimulated cAMP accumulation. Naloxone, after chronic HERK (but not DAMGO) induced a large increase in forskolin‐stimulated cAMP accumulation. Viewed collectively with published data, the current data indicate that both internalizing and noninternalizing μ ‐agonists produce cellular signs of tolerance and dependence. Synapse 61:166–175, 2007. Published 2006 Wiley‐Liss, Inc.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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