Stephanie S. Schweiker

Preliminary investigations into triazole derived androgen receptor antagonists

A range of 1,4-substituted-1,2,3-N-phenyltriazoles were synthesized and evaluated as non-steroidal androgen receptor (AR) antagonists. The motivation for this study was to replace the N-phenyl amide portion of small molecule antiandrogens with a 1,2,3-triazole and determine effects, if any, on biological activity. The synthetic methodology presented herein is robust, high yielding and extremely rapid. Using this methodology a series of 17 N-aryl triazoles were synthesized from commercially available starting materials in less than 3h. After preliminary biological screening at 20 and 40 μM, the most promising three compounds were found to display IC50 values of 40-50 μM against androgen dependent (LNCaP) cells and serve as a starting point for further structure-activity investigations. All compounds in this work were the focus of an in silico study to dock the compounds into the human androgen receptor ligand binding domain (hARLBD) and compare their predicted binding affinity with known antiandrogens. A comparison of receptor-ligand interactions for the wild type and T877A mutant AR revealed two novel polar interactions. One with Q738 of the wild type site and the second with the mutated A877 residue.

Synthesis and preliminary investigations into novel 1,2,3-triazole-derived androgen receptor antagonists inspired by bicalutamide.

A versatile and high yielding synthesis of novel androgen receptor (AR) antagonists is presented. Using this methodology, six 1,4-substituted-1,2,3-triazole derived bicalutamide mimics were synthesised in five steps and in isolated overall yields from 41% to 85%. Evaluation of these compounds for their anti-proliferative properties against androgen dependent (LNCaP) and independent (PC-3) cells showed promising IC50 values of 34-45 μM and 29-151 μM, respectively. The data suggest that the latter compounds may be an excellent starting point for the development of prostate cancer therapeutics for both androgen dependent and independent forms of this disease. Docking of these compounds (each enantiomer) in silico into the T877A mutated androgen receptor, as possessed by LNCaP cells, was also undertaken.

Synthesis, screening and docking of small heterocycles as glycogen phosphorylase inhibitors.

A series of morpholine substituted amino acids (phenylalanine, leucine, lysine and glutamic acid) was synthesized. A fragment-based screening approach was then used to evaluate a series of small heterocycles, including morpholine, oxazoline, dihydro-1,3-oxazine, tetrahydro-1,3-oxazepine, thiazoline, tetrahydro-1,3-pyrimidine, tetrahydro-1,3-diazepine and hexahydro-1H-benzimidazole, as potential inhibitors of Glycogen Phosphorylase a. Thiazoline 7 displayed an improved potency (IC50 of 25 μM) and had good LE and LELP values, as compared to heterocycles 1, 5, 9-13 and 19 (IC50 values of 1.1 mM-23.9 mM). A docking study using the crystal structure of human liver Glycogen Phosphorylase, provided insight into the interactions of heterocycles 5, 7, 9-13 and 19 with Glycogen Phosphorylase.

A Practical Guide to Molecular Docking and Homology Modelling for Medicinal Chemists

Elucidating details of the relationship between molecular structure and a particular biological end point is essential for successful, rational drug discovery. Molecular docking is a widely accepted tool for lead identification however, navigating the intricacies of the software can be daunting. Our objective was therefore to provide a step-by-step guide for those interested in incorporating contemporary basic molecular docking and homology modelling into their design strategy. Three molecular docking programs, AutoDock4, SwissDock and Surflex-Dock, were compared in the context of a case study where a set of steroidal and non-steroidal ligands were docked into the human androgen receptor (hAR) using both rigid and flexible target atoms. Metrics for comparison included how well each program predicted the X-ray structure orientation via root mean square deviation (rmsd), predicting known actives via ligand ranking and comparison to biological data where available. Benchmarking metrics were discussed in terms of identifying accurate and reliable results. For cases where no three dimensional structure exists, we provided a practical example for creating a homology model using Swiss-Model. Results showed an rmsd between X-ray ligands from wild-type and mutant receptors and docked poses were 4.15Å and 0.83Å (SwissDock), 2.69Å and 8.80Å (AutoDock4) and 0.39Å and 0.71Å (Surflex-Dock) respectively. Surflex-Dock performed consistently well in pose prediction (less than 2Å) while Auto- Dock4 predicted known active non-steroidal antiandrogens most accurately. Introducing flexibility into target atoms produced the largest degree of change in ligand ranking in Surflex-Dock. We produced a viable homology model of the P2X1 purireceptor for subsequent docking analysis.

Synthesis of new modified truncated peptides and inhibition of glycogen phosphorylase.

The first solution state structural analysis (NMR) of the C‐terminal sequence of human GL that binds to glycogen phosphorylase a (GPa), PEWPSYLGYEKLGPYY‐NH2 (1), showed it to be in a random coil conformation. This was supported by molecular dynamics simulation (modelled in solution) using NAMD 2.6. The conformational ambiguity of the peptide makes the structural arrangement of the peptide (and internal residues) strongly dependent on the environment. Thirteen tetra‐peptide fragments of the C‐terminal sequence, YEKLG‐NH2, and the corresponding tri‐ and di‐peptide sequences were used in a fragment screen against GPa. Compound 2 (H‐GPYY‐NH2) did not give an IC50 value, whereas PEWPSYLGYEKLGPYY‐NH2 (1) displayed an IC50 of 34 µM against GPa. Truncated peptides derived from 1, (EKL‐NH2, EKLG‐NH2, and AcEKNH2) inhibited GPa (21%, 32%, 63%, respectively at 22 mM). These studies suggest key residues within the peptide chain have additional molecular interactions with GPa. The interaction of intra‐sequence residues in combination with the terminal residues of PEWPSYLGYEKLGPYY with GPa may form the basis for the design of new inhibitors of GPa. Copyright

Poly(ADP-ribose)polymerase, member 14 (PARP14) Inhibitors and Possible Strategies for Designing Selective PARP14 Inhibitors.

Poly(ADP-ribose)polymerase, member 14 (PARP14, alternatively named ARTD8, BAL2, and COAST6) is an intracellular mono(ADP-ribosyl) transferase. PARP14 transfers a negatively charged ADP-ribose unit from a donor NAD+ molecule onto a target protein, post-translationally. PARP14s domain architecture consists of three macrodomains (Macro1, Macro2 and Macro3), a WWE domain and an ARTD (or catalytic domain). The Macro2 and Macro3 domains bind ADPribose (ADPr) with high affinity, whereas the WWE domain stabilizes the protein structure by binding to ADPr derivatives. The catalytic domain is involved in binding the NAD+ and catalyzing the mono- ADP-ribosylation reaction. PARP14 has been identified as a possible anti-cancer and antiinflammatory target. Acting as a transcriptional co-activator for STAT6, PARP14 acts to promote the over activation of the Th2 immune response, thus promoting the metabolic change to an anaerobic state (Warburg effect) and activation of cell survival pathways through JNK2 and the PGI/AMF complex. These changes are consistent with the metabolic sophistication observed in cancer, and the immune imbalance in inflammatory diseases. Current literature on selective and unselective PARP14 inhibitors are reviewed and discussed. Although there is no evidence that selective PARP inhibitors would be advantageous we have proposed some strategies for future design of selective PARP14 inhibitors.

Can we "starve cancer cells to death" with selective parp14 inhibitors?

COSAs 43 and ANZBCTGs 38 Annual Scientific Meetings. Partners for Progress in Breast Cancer Research and Care. 15–17 November