Selective Inhibitors of Autophagy Reveal New Link between the Cell Cycle and Autophagy and Lead to Discovery of Novel Synergistic Drug Combinations.

Autophagy is a conserved metabolic pathway that is central to many diseases. Recently, there has been a lot of interest in targeting autophagy with small molecule inhibitors as a possible therapeutic strategy. However, many of the compounds used for autophagy are nonselective. Here, we explored the inhibition of autophagy in pancreatic cancer cells using established selective small molecule inhibitors and discovered an unexpected link between the autophagy pathway and progression through the cell cycle. Our findings revealed that treatments with inhibitors that have different autophagy pathway targets block cell replication and activate other metabolic pathways to compensate for the blockade in autophagy. An unbiased screen looking for known drugs that might synergize with autophagy inhibition revealed new combination treatments that might provide a blueprint for therapeutic approaches to pancreatic cancer. The drugs quizartinib and THZ1 showed a strong synergistic effect in pancreatic cells with autophagy inhibition.

The HIV protease inhibitor, ritonavir, corrects diverse brain phenotypes across development in mouse model of DYT-TOR1A dystonia.

Dystonias are a group of chronic movement-disabling disorders for which highly effective oral medications or disease-modifying therapies are lacking. The most effective treatments require invasive procedures such as deep brain stimulation. In this study, we used a high-throughput assay based on a monogenic form of dystonia, DYT1 (DYT-TOR1A), to screen a library of compounds approved for use in humans, the NCATS Pharmaceutical Collection (NPC; 2816 compounds), and identify drugs able to correct mislocalization of the disease-causing protein variant, ∆E302/3 hTorsinA. The HIV protease inhibitor, ritonavir, was among 18 compounds found to normalize hTorsinA mislocalization. Using a DYT1 knock-in mouse model to test efficacy on brain pathologies, we found that ritonavir restored multiple brain abnormalities across development. Ritonavir acutely corrected striatal cholinergic interneuron physiology in the mature brain and yielded sustained correction of diffusion tensor magnetic resonance imaging signals when delivered during a discrete early developmental window. Mechanistically, we found that, across the family of HIV protease inhibitors, efficacy correlated with integrated stress response activation. These preclinical results identify ritonavir as a drug candidate for dystonia with disease-modifying potential.

Identification, design and synthesis of novel pyrazolopyridine influenza virus nonstructural protein 1 antagonists.

Nonstructural protein 1 (NS1) plays a crucial function in the replication, spread, and pathogenesis of influenza virus by inhibiting the host innate immune response. Here we report the discovery and optimization of novel pyrazolopyridine NS1 antagonists that can potently inhibit influenza A/PR/8/34 replication in MDCK cells, rescue MDCK cells from cytopathic effects of seasonal influenza A strains, reverse NS1-dependent inhibition of IFN-ß gene expression, and suppress the slow growth phenotype in NS1-expressing yeast. These pyrazolopyridines will enable researchers to investigate NS1 function during infection and how antagonists can be utilized in the next generation of treatments for influenza infection.

Canvass: A Crowd-Sourced, Natural-Product Screening Library for Exploring Biological Space.

Natural products and their derivatives continue to be wellsprings of nascent therapeutic potential. However, many laboratories have limited resources for biological evaluation, leaving their previously isolated or synthesized compounds largely or completely untested. To address this issue, the Canvass library of natural products was assembled, in collaboration with academic and industry researchers, for quantitative high-throughput screening (qHTS) across a diverse set of cell-based and biochemical assays. Characterization of the library in terms of physicochemical properties, structural diversity, and similarity to compounds in publicly available libraries indicates that the Canvass library contains many structural elements in common with approved drugs. The assay data generated were analyzed using a variety of quality control metrics, and the resultant assay profiles were explored using statistical methods, such as clustering and compound promiscuity analyses. Individual compounds were then sorted by structural class and activity profiles. Differential behavior based on these classifications, as well as noteworthy activities, are outlined herein. One such highlight is the activity of (-)-2(S)-cathafoline, which was found to stabilize calcium levels in the endoplasmic reticulum. The workflow described here illustrates a pilot effort to broadly survey the biological potential of natural products by utilizing the power of automation and high-throughput screening.

Nitrosopurines en route to potently cytotoxic asmarines.

A nitrosopurine ene reaction easily assembles the asmarine pharmacophore and transmits remote stereochemistry to the diazepine-purine hetereocycle. This reaction generates potent cytotoxins which exceed the potency of asmarine A (1.2 µM IC50) and supersede the metabolites as useful leads for biological discovery.

Simple, chemoselective hydrogenation with thermodynamic stereocontrol.

Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure.