Macrocyclic scaffolds are commonly found in bioactive natural products and pharmaceutical molecules. So far, a large number of macrocyclic natural products have been isolated and synthesized. The construction of macrocycles is generally considered as a crucial and challenging step in the synthesis of macrocyclic natural products. Over the last several decades, numerous efforts have been undertaken toward the synthesis of complex naturally occurring macrocycles and great progresses have been made to advance the field of total synthesis. The commonly used synthetic methodologies toward macrocyclization include macrolactonization, macrolactamization, transition metal-catalyzed cross coupling, ring-closing metathesis, and click reaction, among others. Selected recent examples of macrocyclic synthesis of natural products and druglike macrocycles with significant biological relevance are highlighted in each class. The primary goal of this review is to summarize currently used macrocyclic drugs, highlight the therapeutic potential of this underexplored drug class and outline the general synthetic methodologies for the synthesis of macrocycles.

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Interactions between WD40 repeat domain protein 5 (WDR5) and its various partners such as mixed lineage leukemia (MLL) and c-MYC are essential for sustaining oncogenesis in human cancers. However, inhibitors that block protein-protein interactions (PPIs) between WDR5 and its binding partners exhibit modest cancer cell killing effects and lack in vivo efficacy. Here, we present pharmacological degradation of WDR5 as a promising therapeutic strategy for treating WDR5-dependent tumors and report two high-resolution crystal structures of WDR5degrader-E3 ligase ternary complexes. We identified an effective WDR5 degrader via structure-based design and demonstrated its in vitro and in vivo antitumor activities. On the basis of the crystal structure of an initial WDR5 degrader in complex with WDR5 and the E3 ligase von Hippel-Lindau (VHL), we designed a WDR5 degrader, MS67, and demonstrated the high cooperativity of MS67 binding to WDR5 and VHL by another ternary complex structure and biophysical characterization. MS67 potently and selectively depleted WDR5 and was more effective than WDR5 PPI inhibitors in suppressing transcription of WDR5-regulated genes, decreasing the chromatin-bound fraction of MLL complex components and c-MYC, and inhibiting the proliferation of cancer cells. In addition, MS67 suppressed malignant growth of MLL-rearranged acute myeloid leukemia patient cells in vitro and in vivo and was well tolerated in vivo. Collectively, our results demonstrate that structure-based design can be an effective strategy to identify highly active degraders and suggest that pharmacological degradation of WDR5 might be a promising treatment for WDR5-dependent cancers.

SUMMARY Glutamine is thought to play an important role in cancer cells by being deaminated via glutaminolysis to α-ketoglutarate (aKG) to fuel the tricarboxylic acid (TCA) cycle. Supporting this notion, aKG supplementation can restore growth/survival of glutamine-deprived cells. However, pancreatic cancers are often poorly vascularized and limited in glutamine supply, in alignment with recent concerns on the significance of glutaminolysis in pancreatic cancer. Here, we show that aKG-mediated rescue of glutamine-deprived pancreatic ductal carcinoma (PDAC) cells requires glutamate ammonia ligase (GLUL), the enzyme responsible for de novo glutamine synthesis. GLUL-deficient PDAC cells are capable of the TCA cycle but defective in aKG-coupled glutamine biosynthesis and subsequent nitrogen anabolic processes. Importantly, GLUL expression is elevated in pancreatic cancer patient samples and in mouse PDAC models. GLUL ablation suppresses the development of KrasG12D-driven murine PDAC. Therefore, GLUL-mediated glutamine biosynthesis couples the TCA cycle with nitrogen anabolism and plays a critical role in PDAC.

Several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors have been developed and approved by Food and Drug Administration for the treatment of non-small-cell lung cancers, but their efficacy can be compromised by acquired drug resistance conferred by EGFR-mutant variants. Here, we described the discovery of a novel E3 ligase von Hippel-Lindau-recruiting EGFR degrader, MS39 (compound 6), and a first-in-class E3 ligase cereblon-recruiting EGFR degrader, MS154 (compound 10), using the proteolysis targeting chimera technology. These compounds potently induced the degradation of mutant but not wild-type EGFR in an E3 ligasedependent manner in cancer cell lines and effectively suppressed the growth of lung cancer cells

Using a panel of cancer cell lines, we characterized a novel degrader of AKT, MS21. In mutant PI3K/PTEN pathway lines, AKT degradation was superior to AKT kinase inhibition for reducing cell growth and sustaining lower signalling over many days. AKT degradation but not kinase inhibition profoundly lowered Aurora kinase B (AURKB) protein, which is known to be essential for cell division, and induced G2/M arrest and hyperploidy. PI3K activated AKT phosphorylation of AURKB on threonine 73, which protected it from proteasome degradation. A mutant of AURKB (T73E) that mimics phosphorylation and blocks degradation rescued cells from growth inhibition. Degrader resistant lines were associated with low AKT phosphorylation, wild type PI3K/PTEN status, and mutation of KRAS/BRAF. Pan-cancer analysis identified that 19% of cases have PI3K/PTEN pathway mutation without RAS pathway mutation, suggesting that these cancer patients could benefit from AKT degrader therapy that leads to loss of AURKB.

G protein-coupled receptors (GPCRs) are capable of downstream signaling through distinct noncanonical pathways such as β-arrestins in addition to the canonical G protein-dependent pathways. GPCR ligands that differentially activate the downstream signaling pathways are termed functionally selective or biased ligands. A class of novel non-catechol G protein-biased agonists of the dopamine D 1 receptor (D 1 R) was recently disclosed. We conducted the first comprehensive structure−functional selectivity relationship study measuring G S and β-arrestin2 recruitment activities focused on four regions of this scaffold, resulting in over 50 analogs with diverse functional selectivity profiles. Some compounds became potent full agonists of β-arrestin2

Gene expression can be activated or suppressed using CRISPR/Cas9 systems. However, tools that enable dose-dependent activation of gene expression without the use of exogenous transcription regulatory proteins are lacking. Here we describe chemical epigenetic modifiers (CEMs) designed to activate the expression of target genes by recruiting components of the endogenous chromatin activating machinery, eliminating the need for exogenous transcriptional activators. The system has two parts: catalytically inactive Cas9 (dCas9) in complex with FK506 binding protein (FKBP), and a CEM consisting of FK506 linked to a molecule that interacts with cellular epigenetic machinery. We show that CEMs upregulate gene expression at target endogenous loci up to 20fold or more depending on the gene. We also demonstrate dose-dependent control of transcriptional activation, function across multiple diverse genes, reversibility of CEM activity, and specificity of our best in class CEM genome wide. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: