Diastereomeric 6-desoxy-6-spiro-alpha-methylene-gamma-butyrolactone derivatives of naltrexone and oxymorphone. Selective irreversible inhibition of naltrexone binding in an opioid receptor preparation by a conformationally restricted michael acceptor ligand

Programmed death ligand 1 signals in cancer cells

The paradigm of surface-expressed programmed death ligand 1 (PDL1) signalling to immune cell programmed death 1 (PD1) to inhibit antitumour immunity has helped to develop effective and revolutionary immunotherapies using antibodies blocking these cell-extrinsic interactions. The recent discovery of cancer cell-intrinsic PDL1 signals has broadened understanding of pathologic tumour PDL1 signal consequences that now includes control of tumour growth and survival pathways, stemness, immune effects, DNA damage responses and gene expression regulation. Many such effects are PD1-independent. These insights demonstrate that the prevailing cell-extrinsic PDL1 signalling paradigm is useful, but incomplete in important respects. This Perspective discusses historical and recent advances in understanding cancer cell-intrinsic PDL1 signals, mechanisms for signal controls and important immunopathologic consequences including resistance to cytotoxic agents, targeted small molecules and immunotherapies. Cancer cell-intrinsic PDL1 signals present novel drug discovery targets and also have potential as reliable treatment response biomarkers. Cancer cell-intrinsic PD1 signals and cell-intrinsic PDL1 signals in non-cancer cells are discussed briefly, as are PDL1 signals from soluble and vesicle-bound PDL1 and PDL1 isoforms. We conclude with suggestions for addressing the most pressing challenges and opportunities in this rapidly developing field.

Michael acceptor approach to the design of new salvinorin A-based high affinity ligands for the kappa-opioid receptor

The neoclerodane diterpenoid salvinorin A is a major secondary metabolite isolated from the psychoactive plant Salvia divinorum. Salvinorin A has been shown to have high affinity and selectivity for the κ-opioid receptor (KOR). To study the ligand-receptor interactions that occur between salvinorin A and the KOR, a new series of salvinorin A derivatives bearing potentially reactive Michael acceptor functional groups at C-2 was synthesized and used to probe the salvinorin A binding site. The κ-, δ-, and μ-opioid receptor (KOR, DOR and MOR, respectively) binding affinities and KOR efficacies were measured for the new compounds. Although none showed wash-resistant irreversible binding, most of them showed high affinity for the KOR, and some exhibited dual affinity to KOR and MOR. Molecular modeling techniques based on the recently-determined crystal structure of the KOR combined with results from mutagenesis studies, competitive binding, functional assays and structure-activity relationships, and previous salvinorin A-KOR interaction models were used to identify putative interaction modes of the new compounds with the KOR and MOR.

Chloroacryloyl amides and alpha-methylenelactones from naltrexone, oxymorphone and fentanyl

A series of chloroacryloyl amides and alpha-methylenelactones were prepared from naltrexone and oxymorphone and some chloroacryloyl amides from fentanyl were prepared as potential Michael acceptors and irreversible ligands. The relative rates of Michael additions of p-methoxybenzenethiol to the double bonds were measured in an NMR spectrometer. The IC50's in rat brain homogenates and the irreversible binding to rat brain membranes were determined. In the methylene-lactone series, it was found that both the alpha and beta isomers derived from naltrexone and oxymorphone were excellent Michael acceptors, but only the beta isomers were more active in the opioid binding assays. The beta isomer derived from naltrexone was an irreversible ligand whereas the oxymorphone analogue was active only in the presence of 100 mM NaCl. In the chloroacryloyl series, only the alpha-chloroacryloyl amide derived from beta naltrexamine proved to be an irreversible binding ligand in the absence of NaCl. It was an excellent Michael acceptor. Under the conditions of our experiments, beta-FNA was a poor Michael acceptor and did not behave as an irreversible ligand in rat membranes.