SUMMARY Biased agonism has been proposed as a means to separate desirable and adverse drug responses downstream of G protein-coupled receptor (GPCR) targets. Herein we describe structural features of a series of mu opioid receptor (MOR)-selective agonists that preferentially activate receptor to couple to G proteins or to recruit βarrestin proteins. By comparing relative bias for MOR-mediated signaling in each pathway, we demonstrate a strong correlation between the respiratory suppression/antinociception therapeutic window in a series of compounds spanning a wide range of signaling bias. We find that βarrestin-biased compounds, such as fentanyl, are more likely to induce respiratory suppression at weak analgesic doses, while G protein signaling-bias broadens the therapeutic window, allowing for antinociception in the absence of respiratory suppression.

Myc oncoproteins induce genes driving aerobic glycolysis, including lactate dehydrogenase-A that generates lactate. Here we report that Myc controls transcription of the lactate transporter SLC16A1/MCT1, and that elevated MCT1 levels are manifest in premalignant and neoplastic Eμ-Myc transgenic B cells and in human malignancies with MYC or MYCN involvement. Notably, disrupting MCT1 function leads to an accumulation of intracellular lactate that rapidly disables tumor cell growth and glycolysis, provoking marked alterations in glycolytic intermediates, and reductions in glucose transport, and in levels of ATP, NADPH and glutathione. Reductions in glutathione then lead to increases in hydrogen peroxide, mitochondrial damage and, ultimately, cell death. Finally, forcing glycolysis by metformin treatment augments this response and the efficacy of MCT1 inhibitors, suggesting an attractive combination therapy for MYC/MCT1-expressing malignancies.

The amygdala-dependent molecular mechanisms driving the onset and persistence of posttraumatic stress disorder (PTSD) are poorly understood. Recent observational studies have suggested that opioid analgesia in the aftermath of trauma may decrease the development of PTSD. Using a mouse model of dysregulated fear, we found altered expression within the amygdala of the Oprl1 gene (opioid receptor–like 1), which encodes the amygdala nociceptin (NOP)/orphanin FQ receptor (NOP-R). Systemic and central amygdala infusion of SR-8993, a new highly selective NOP-R agonist, impaired fear memory consolidation. In humans, a single-nucleotide polymorphism (SNP) within OPRL1 is associated with a self-reported history of childhood trauma and PTSD symptoms (n = 1847) after a traumatic event. This SNP is also associated with physiological startle measures of fear discrimination and magnetic resonance imaging analysis of amygdala-insula functional connectivity. Together, these data suggest that Oprl1 is associated with amygdala function, fear processing, and PTSD symptoms. Further, our data suggest that activation of the Oprl1/NOP receptor may interfere with fear memory consolidation, with implications for prevention of PTSD after a traumatic event.

In statin-treated patients with low HDL-C, high-dose modified-release NA, compared with placebo, significantly reduces carotid atherosclerosis within 12 months. (Oxford Niaspan Study: Effects of Niaspan on Atherosclerosis and Endothelial Function; NCT00232531).

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ADAM10 and ADAM17 have been shown to contribute to the acquired drug resistance of HER2-positive breast cancer in response to trastuzumab. The majority of ADAM10 and ADAM17 inhibitor development has been focused on the discovery of compounds that bind the active site zinc, however, in recent years, there has been a shift from active site to secondary substrate binding site (exosite) inhibitor discovery in order to identify non-zinc-binding molecules. In the present work a glycosylated, exosite-binding substrate of ADAM10 and ADAM17 was utilized to screen 370,276 compounds from the MLPCN collection. As a result of this uHTS effort, a selective, time-dependent, non-zinc-binding inhibitor of ADAM10 with Ki = 883 nM was discovered. This compound exhibited low cell toxicity and was able to selectively inhibit shedding of known ADAM10 substrates in several cell-based models. We hypothesize that differential glycosylation of these cognate substrates is the source of selectivity of our novel inhibitor. The data indicate that this novel inhibitor can be used as an in vitro and, potentially, in vivo, probe of ADAM10 activity. Additionally, results of the present and prior studies strongly suggest that glycosylated substrate are applicable as screening agents for discovery of selective ADAM probes and therapeutics.

A highly stereoselective total synthesis of (-)-bafilomycin A(1), the naturally occurring enantiomer of this potent vacuolar ATPase inhibitor, is described. The synthesis features the highly stereoselective aldol reaction of methyl ketone 8b and aldehyde 60c and a Suzuki cross-coupling reaction of the highly functionalized advanced intermediates 12 and 39. Vinyl iodide 12 was synthesized by a 14-step sequence starting from the readily available beta-alkoxy aldehyde 14, while the vinylboronic acid component 39 was synthesized by a nine-step sequence from beta-hydroxy-alpha-methyl butyrate 44 via a sequence involving the alpha-methoxypropargylation of chiral aldehyde 49 with the alpha-methoxypropargylstannane reagent 54. Syntheses of fragments 12 and 39 also feature diastereoselective double asymmetric crotylboration reactions to set several of the critical stereocenters. The Suzuki cross-coupling of 12 and 39 provided seco ester 40, which following conversion to the seco acid underwent smooth macrolactonization to give 41. The success of the macrocyclization required that C(7)-OH be unprotected. The Mukaiyama aldol reaction between aldehyde 60c and the TMS enol ether generated from 8b provided aldol 65 with high diastereoselectivity. Finally, all silicon protecting groups were removed by treatment of the penultimate intermediate 65 with TAS-F (tris(dimethylamino)sulfonium difluorotrimethylsilicate), thereby completing the total synthesis of (-)-bafilomycin A(1).

While mu opioid receptor (MOR) agonists are especially effective as broad-spectrum pain relievers, it has been exceptionally difficult to achieve a clear separation of analgesia from many problematic side effects. Recently, many groups have sought MOR agonists that induce minimal βarrestin-mediated signaling because MOR agonist-treated βarrestin2 knockout mice were found to display enhanced antinociceptive effects with significantly less respiratory depression and tachyphylaxis. Substantial data now exists to support the premise that G protein signaling biased MOR agonists can be effective analgesic agents. We recently showed that, within a chemical series, the degree of bias correlates linearly with the magnitude of the respiratory safety index. Herein we describe the synthesis and optimization of piperidine benzimidazolone MOR agonists that together display a wide range of bias (G/βarr2). We identify structural features affecting potency and maximizing bias and show that many compounds have desirable properties, such as long half-lives and high brain penetration.