Sterol regulatory element-binding proteins (SREBPs) are master transcriptional regulators of the mevalonate pathway and lipid metabolism and represent an attractive therapeutic target for lipid ...metabolic disorders. SREBPs are maintained in the endoplasmic reticulum (ER) in a tripartite complex with SREBP cleavage-activating protein (SCAP) and insulin-induced gene protein (INSIG). When new lipid synthesis is required, the SCAP-SREBP complex dissociates from INSIG and undergoes ER-to-Golgi transport where the N-terminal transcription factor domain is released by proteolysis. The mature transcription factor translocates to the nucleus and stimulates expression of the SREBP gene program. Previous studies showed that dipyridamole, a clinically prescribed phosphodiesterase (PDE) inhibitor, potentiated statin-induced tumor growth inhibition. Dipyridamole limited nuclear accumulation of SREBP, but the mechanism was not well resolved. In this study, we show that dipyridamole selectively blocks ER-to-Golgi movement of the SCAP-SREBP complex and that this is independent of its PDE inhibitory activity.
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•Dipyridamole, a PDE inhibitor, decreases lipogenesis by inhibiting SREBP maturation•Dipyridamole blocks SREBP independent of its PDE inhibitory action•A clickable photoprobe dipyridamole derivative binds to INSIG and SCAP•Dipyridamole derivatives are potentially therapeutic for lipid disorders
Esquejo et al. report that dipyridamole, an FDA-approved anti-thrombotic phosphodiesterase (PDE) inhibitor, impedes endoplasmic reticulum to Golgi trafficking of sterol regulatory element-binding proteins (SREBPs) preventing their activation. A chemically modified version of dipyridamole that has no effect on PDE remains effective at SREBP blockage.
The particulate guanylyl cyclase A receptor (GC-A), via activation by its endogenous ligands atrial natriuretic peptide (ANP) and b-type natriuretic peptide (BNP), possesses beneficial biological ...properties such as blood pressure regulation, natriuresis, suppression of adverse remodeling, inhibition of the renin-angiotensin-aldosterone system, and favorable metabolic actions through the generation of its second messenger cyclic guanosine monophosphate (cGMP). Thus, the GC-A represents an important molecular therapeutic target for cardiovascular disease and its associated risk factors. However, a small molecule that is orally bioavailable and directly targets the GC-A to potentiate cGMP has yet to be discovered. Here, we performed a cell-based high-throughput screening campaign of the NIH Molecular Libraries Small Molecule Repository, and we successfully identified small molecule GC-A positive allosteric modulator (PAM) scaffolds. Further medicinal chemistry structure-activity relationship efforts of the lead scaffold resulted in the development of a GC-A PAM, MCUF-651, which enhanced ANP-mediated cGMP generation in human cardiac, renal, and fat cells and inhibited cardiomyocyte hypertrophy in vitro. Further, binding analysis confirmed MCUF-651 binds to GC-A and selectively enhances the binding of ANP to GC-A. Moreover, MCUF-651 is orally bioavailable in mice and enhances the ability of endogenous ANP and BNP, found in the plasma of normal subjects and patients with hypertension or heart failure, to generate GC-A-mediated cGMP ex vivo. In this work, we report the discovery and development of an oral, small molecule GC-A PAM that holds great potential as a therapeutic for cardiovascular, renal, and metabolic diseases.
Polyamine biosynthesis is regulated by ornithine decarboxylase (ODC), which is transcriptionally activated by c-Myc. A large library was screened to find molecules that potentiate the ODC inhibitor, ...difluoromethylornithine (DFMO). Anthranilic acid derivatives were identified as DFMO adjunct agents. Further studies identified the far upstream binding protein 1 (FUBP1) as the target of lead compound 9. FUBP1 is a single-stranded DNA/RNA binding protein and a master controller of specific genes including c-Myc and p21. We showed that 9 does not inhibit 3H-spermidine uptake yet works synergistically with DFMO to limit cell growth in the presence of exogenous spermidine. Compound 9 was also shown to inhibit the KH4 FUBP1–FUSE interaction in a gel shift assay, bind to FUBP1 in a ChIP assay, reduce both c-Myc mRNA and protein expression, increase p21 mRNA and protein expression, and deplete intracellular polyamines. This promising hit opens the door to new FUBP1 inhibitors with increased potency.
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The chemokine system plays an important role in mediating a proinflammatory microenvironment for tumor growth in hepatocellular carcinoma (HCC). The CXCR6 receptor and its natural ...ligand CXCL16 are expressed at high levels in HCC cell lines and tumor tissues and receptor expression correlates with increased neutrophils in these tissues contributing to poor prognosis in patients. Availability of pharmacologcal tools targeting the CXCR6/CXCL16 axis are needed to elucidate the mechanism whereby neutrophils are affected in the tumor environment. We report the discovery of a series of small molecules with an exo-3.3.1azabicyclononane core. Our lead compound 81 is a potent (EC50 = 40 nM) and selective orally bioavailable small molecule antagonist of human CXCR6 receptor signaling that significantly decreases tumor growth in a 30-day mouse xenograft model of HCC.
Oxidative injury to cardiomyocytes plays a critical role in cardiac pathogenesis following myocardial infarction. Transplantation of stem cell-derived cardiomyocytes has recently progressed as a ...novel treatment to repair damaged cardiac tissue but its efficacy has been limited by poor survival of transplanted cells owing to oxidative stress in the post-transplantation environment. Identification of small molecules that activate cardioprotective pathways to prevent oxidative damage and increase survival of stem cells post-transplantation is therefore of great interest for improving the efficacy of stem cell therapies. This report describes a chemical biology phenotypic screening approach to identify and validate small molecules that protect human-induced pluripotent stem cell cardiomyocytes (hiPSC-CMs) from oxidative stress. A luminescence-based high-throughput assay for cell viability was used to screen a diverse collection of 48,640 small molecules for protection of hiPSC-CMs from peroxide-induced cell death. Cardioprotective activity of "hit" compounds was confirmed using impedance-based detection of cardiomyocyte monolayer integrity and contractile function. Structure-activity relationship studies led to the identification of a potent class of compounds with 4-(pyridine-2-yl)thiazole scaffold. Examination of gene expression in hiPSC-CMs revealed that the hit compound, designated cardioprotectant 312 (CP-312), induces robust upregulation of heme oxygenase-1, a marker of the antioxidant response network that has been strongly correlated with protection of cardiomyocytes from oxidative stress. CP-312 therefore represents a novel chemical scaffold identified by phenotypic high-throughput screening using hiPSC-CMs that activates the antioxidant defense response and may lead to improved pharmacological cardioprotective therapies.
Nematodes parasitize ∼1/3 of humans worldwide, and effective treatment via administration of anthelmintics is threatened by growing resistance to current therapies. The nematode transcription factor ...SKN-1 is essential for development of embryos and upregulates the expression of genes that result in modification, conjugation, and export of xenobiotics, which can promote resistance. Distinct differences in regulation and DNA binding relative to mammalian Nrf2 make SKN-1 a promising and selective target for the development of anthelmintics with a novel mode of action that targets stress resistance and drug detoxification. We report 17 (ML358), a first in class small molecule inhibitor of the SKN-1 pathway. Compound 17 resulted from a vanillamine-derived hit identified by high throughput screening that was advanced through analog synthesis and structure–activity studies. Compound 17 is a potent (IC50 = 0.24 μM, E max = 100%) and selective inhibitor of the SKN-1 pathway and sensitizes the model nematode C. elegans to oxidants and anthelmintics. Compound 17 is inactive against Nrf2, the homologous mammalian detoxification pathway, and is not toxic to C. elegans (LC50 > 64 μM) and Fa2N-4 immortalized human hepatocytes (LC50 > 5.0 μM). In addition, 17 exhibits good solubility, permeability, and chemical and metabolic stability in human and mouse liver microsomes. Therefore, 17 is a valuable probe to study regulation and function of SKN-1 in vivo. By selective targeting of the SKN-1 pathway, 17 could potentially lead to drug candidates that may be used as adjuvants to increase the efficacy and useful life of current anthelmintics.
A scaffold-hop program seeking full agonists of the neurotensin-1 (NTR1) receptor identified the probe molecule ML301 (1) and associated analogs, including its naphthyl analog (14) which exhibited ...similar properties. Compound 1 showed full agonist behavior (79-93%) with an EC50 of 2.0-4.1μM against NTR1. Compound 1 also showed good activity in a Ca mobilization FLIPR assay (93% efficacy at 298nM), consistent with it functioning via the Gq coupled pathway, and good selectivity relative to NTR2 and GPR35. In further profiling, 1 showed low potential for promiscuity and good overall pharmacological data. This report describes the discovery, synthesis, and SAR of 1 and associated analogs. Initial in vitro pharmacologic characterization is also presented.
Objective Although the endovascular aneurysm repair trial 2 (EVAR-2) demonstrated no benefit of EVAR in high-risk (HR) patients, EVAR is still performed widely in this patient cohort. This study ...compares the midterm outcomes after EVAR in HR patients with those in normal-risk (NR) patients. In turn, these data are compared with the EVAR-2 data. Methods A retrospective review from January 2006 to December 2013 identified 247 patients (75 HR 30.4%, 172 NR 69.6%) who underwent elective EVAR for infrarenal aortic aneurysm in an academic tertiary institution and its affiliated Veterans Administration hospital. The same HR criteria used in the EVAR-2 trial were employed. Overall survival, graft-related complications, and reintervention rates were estimated by the Kaplan-Meier method. HR group outcomes were compared with the EVAR-2 data. Results HR patients had a larger abdominal aortic aneurysm size and had a higher prevalence of cardiac disease ( P < .01), chronic obstructive pulmonary disease ( P = .02), renal insufficiency ( P < .01), and cancer ( P < .01). Use of aspirin (63% HR vs 66% NR; P = .6), statin (83% HR vs 72% NR; P = .2), and beta-blockers (71% HR vs 60% NR; P = .2) was similar; in the EVAR-2 trial, the corresponding use of these medications was 58%, 42%, and not available, respectively. Perioperative mortality (0% HR vs 1.2% NR; P = 1.0) and early complication rates (4% HR vs 6% NR; P = .8) were similar. In contrast, perioperative mortality in the EVAR-2 trial was 9%. At a mean follow-up of 3 years, the incidence rates of delayed secondary interventions for aneurysm- or graft-related complications were 7% for HR patients and 10% for NR patients ( P = .5). The 1-, 2-, and 4-year survival rates in HR patients (85%, 77%, 65%) were lower than those in NR patients (97%, 97%, 93%; P < .001), but this was more favorable compared with a 36% 4-year survival in the EVAR-2 trial. No difference was seen in long-term reintervention-free survival in HR and NR patients ( P = .8). Backward stepwise logistic regression analysis identified five prognostic indicators for post-EVAR death: age, chronic kidney disease stages 4 and 5, congestive heart failure, home oxygen use, and current cancer therapy. Conclusions EVAR can be performed in patients unfit for open surgical repair with excellent early survival and long-term durability. These outcomes in the HR group compare more favorably to the EVAR-2 trial data. However, not all HR patients for open surgical repair derive the benefit from EVAR. The decision to proceed with EVAR in HR patients should be individualized, depending on the number and severity of risk factors.
Activation of nuclear factor-kappa B (NF-κB) and related upstream signal transduction pathways have long been associated with the pathogenesis of a variety of inflammatory diseases and has recently ...been implicated in the onset of cancer. This report provides a synthetic and compound-based property summary of five pathway-related small-molecule chemical probes identified and optimized within the National Institutes of Health-Molecular Libraries Probe Center Network (NIH-MLPCN) initiative. The chemical probes discussed herein represent first-in-class, non-kinase-based modulators of the NF-κB signaling pathway, which were identified and optimized through either cellular phenotypic or specific protein-target-based screening strategies. Accordingly, the resulting new chemical probes may allow for better fundamental understanding of this highly complex biochemical signaling network and could advance future therapeutic translation toward the clinical setting.
Iliofemoral acute deep venous thrombosis (DVT) poses increased risk for post-thrombotic syndrome. Absent inferior vena cava (IVC) syndrome is a rare vascular anomaly that can be associated with ...idiopathic DVT in the young patient. It remains unclear whether endovenous thrombolytic intervention for DVT in patients with absent IVC can be successful, given the impaired venous outflow. This case report describes revascularization of bilateral iliofemoral and femoropopliteal DVT using endovascular pharmacomechanical thrombolysis and thrombectomy in a patient with underlying absent IVC syndrome to prevent post-thrombotic morbidity.
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