Perspective for Discovery of Small Molecule IL-6 Inhibitors through Study of Structure-Activity Relationships and Molecular Docking.

Interleukin-6 (IL-6) is a proinflammatory cytokine that plays a key role in the pathogenesis and physiology of inflammatory and autoimmune diseases, such as coronary heart disease, cancer, Alzheimer's disease, asthma, rheumatoid arthritis, and most recently COVID-19. IL-6 and its signaling pathway are promising targets in the treatment of inflammatory and autoimmune diseases. Although, anti-IL-6 monoclonal antibodies are currently being used in clinics, huge unmet medical needs remain because of the high cost, administration-related toxicity, lack of opportunity for oral dosing, and potential immunogenicity of monoclonal antibody therapy. Furthermore, nonresponse or loss of response to monoclonal antibody therapy has been reported, which increases the importance of optimizing drug therapy with small molecule drugs. This work aims to provide a perspective for the discovery of novel small molecule IL-6 inhibitors by the analysis of the structure-activity relationships and computational studies for protein-protein inhibitors targeting the IL-6/IL-6 receptor/gp130 complex.

AIMP2-DX2 provides therapeutic interface to control KRAS-driven tumorigenesis.

Recent development of the chemical inhibitors specific to oncogenic KRAS (Kirsten Rat Sarcoma 2 Viral Oncogene Homolog) mutants revives much interest to control KRAS-driven cancers. Here, we report that AIMP2-DX2, a variant of the tumor suppressor AIMP2 (aminoacyl-tRNA synthetase-interacting multi-functional protein 2), acts as a cancer-specific regulator of KRAS stability, augmenting KRAS-driven tumorigenesis. AIMP2-DX2 specifically binds to the hypervariable region and G-domain of KRAS in the cytosol prior to farnesylation. Then, AIMP2-DX2 competitively blocks the access of Smurf2 (SMAD Ubiquitination Regulatory Factor 2) to KRAS, thus preventing ubiquitin-mediated degradation. Moreover, AIMP2-DX2 levels are positively correlated with KRAS levels in colon and lung cancer cell lines and tissues. We also identified a small molecule that specifically bound to the KRAS-binding region of AIMP2-DX2 and inhibited the interaction between these two factors. Treatment with this compound reduces the cellular levels of KRAS, leading to the suppression of KRAS-dependent cancer cell growth in vitro and in vivo. These results suggest the interface of AIMP2-DX2 and KRAS as a route to control KRAS-driven cancers.

Elucidation of Mechanism for Ligand Efficacy at Leukotriene B4 Receptor 2 (BLT2).

G protein-coupled receptors (GPCRs) have always been important drug targets in the pharmaceutical industry. One major question for the current GPCR drug discovery is how drugs have distinct efficacies at the same GPCR target. Related to this question, we studied how different ligands can have disparate efficacies at Leukotriene B4 receptor (BLT2). By using molecular modeling studies, we predicted that Tyr2716.51 located at TM6 of BLT2 performs as a key trigger for its activation and verified the prediction by site-directed mutagenesis, chemotactic motility studies, which included a chemical derivative of agonist CAY10583. We further identified Asn2756.55 located at TM6 as a weak activation trigger in BLT2 and performed double mutation studies to confirm our computational results. Our results provide strong evidence for the exact mechanism of ligand efficacy at BLT2.

Synthesis and Structure-Activity Relationships of Arylsulfonamides as AIMP2-DX2 Inhibitors for the Development of a Novel Anticancer Therapy.

AIMP2-DX2, a splicing variant of AIMP2, is up-regulated in lung cancer, possesses oncogenic activity, and results in tumorigenesis. Specifically inhibiting the interaction between AIMP2-DX2 and HSP70 to suppress AIMP2-DX2-dependent cancers with small molecules is considered a promising avenue for cancer therapeutics. Optimization of hit BC-DXI-04 (IC50 = 40.1 µM) provided new potent sulfonamide based AIMP2-DX2 inhibitors. Among these, BC-DXI-843 showed improved inhibition against AIMP2-DX2 (IC50 = 0.92 µM) with more than 100-fold selectivity over AIMP2 in a luciferase assay. Several binding assays indicated that this compound effectively induces cancer cell apoptosis by specifically interrupting the interaction between DX2 and HSP70, which leads to the degradation of DX2 via Siah1-mediated ubiquitination. More importantly, BC-DXI-843 demonstrated in vivo efficacy in a tumor xenograft mouse model (H460 cells) at a dosage of 50 mg/kg, suggesting it as a promising lead for development of novel therapeutics targeting AIMP2-DX2 in lung cancer.

Elucidation of the inhibition mechanism of sulfiredoxin using molecular modeling and development of its inhibitors.

When intracellular reactive oxygen species (ROS) increase, cancer cells are more vulnerable to oxidative stress compared to normal cells; thus, the collapse of redox homeostasis can lead to selective death of cancer cells. Indeed, recent studies have shown that inhibition of sulfiredoxin (Srx), which participates in antioxidant mechanisms, induces ROS-mediated cancer cell death. In this paper, we describe how an Srx inhibitor, J14 (4-[[[4-[4-(2-chlor-ophenyl)-1-piperazinyl]-6-phenyl-2-pyrimidinyl]thio]methyl]-benzoic acid), interferes with the antioxidant activity of Srx at the molecular level. We searched for possible binding sites of Srx using a binding site prediction method and uncovered two possible inhibition mechanisms of Srx by J14. Using molecular dynamics simulations and binding free energy calculations, we confirmed that J14 binds to the ATP binding site; therefore, J14 acts as a competitive inhibitor of ATP, settling the question of the two mechanisms. Based on the inhibition mechanism revealed at the atomic level, we designed several derivatives of J14, which led to LMT-328 (4-(((4-(4-(2-Chlorophenyl)piperazin-1-yl)-6-(2,4-dihydroxy-5-isopropylphenyl)pyrimidin-2-yl)thio)methyl)benzoic acid), which is possibly an even more potent inhibitor than J14.

Suppression of Hepatitis C Virus Genome Replication and Particle Production by a Novel Diacylglycerol Acyltransferases Inhibitor.

Diacylglycerol acyltransferases (DGATs) play a critical role in the biosynthesis of endogenous triglycerides (TGs) and formation of lipid droplets (LDs) in the liver. In particular, one member of DGATs, DGAT-1 was reported to be an essential host factor for the efficient production of hepatitis C virus (HCV) particles. By utilizing our previously characterized three different groups of twelve DGAT inhibitors, we found that one of the DGAT inhibitors, a 2-((4-adamantylphenoxy) methyl)-N-(furan-2-ylmethyl)-1H-benzo[d]imidazole-5-carboxam (10j) is a potent suppressor of both HCV genome replication and particle production. 10j was able to induce inhibition of these two critical viral functions in a mutually separate manner. Abrogation of the viral genome replication by 10j led to a significant reduction in the viral protein expression as well. Interestingly, we found that its antiviral effect did not depend on the reduction of TG biosynthesis by 10j. This suggests that the inhibitory activity of 10j against DGATs may not be directly related with its antiviral action.

The efficacy of infliximab combined with surgical treatment of fistulizing perianal Crohn's disease: Comparative analysis according to fistula subtypes.

BACKGROUND/OBJECTIVE: Infliximab is regarded as an effective therapeutic to treat Crohn's disease. This study aimed to assess the efficacy of infliximab combined with surgery and to analyze clinical manifestations according to fistula subtypes in patients with fistulizing perianal Crohn's disease. METHODS: From April 2013 to December 2015, 47 patients with perianal Crohn's disease in two hospitals of South Korea (Goo Hospital, Gangnam Severance Hospital) were evaluated retrospectively. Patients were categorized into two groups as simple fistula (n = 20) and complex fistula group (n = 27). All patients received 5 mg/kg of infliximab intravenously at 0, 2, and 6 weeks after surgical treatments. Then every eight weeks, the responders continued to receive 5 mg/kg infliximab for maintenance therapy. RESULTS: Complete response of induction therapy was 72.3%, and partial response was 27.7%. After maintenance therapy, complete response was 97.9% and partial response was 2.1%. There was no patient without a response to infliximab in this study. The median time to the first fistula closure was 6.00 ± 8.00 weeks. Infliximab was used on average 2.13 ± 0.71 times until the first fistula closure. The rate of recurrence was 8.5% and adverse events were 4.2%. In comparison with clinical manifestations between simple and complex fistula groups, there was no significant difference except for the coexistence of perianal abscess. CONCLUSIONS: Combined surgical and infliximab therapy was efficacious to treat fistulizing perianal Crohn's disease with rapid treatment response and favorable clinical outcomes. It is expected that this top-down strategy with combining surgeries can overcome previous limitations in treating perianal Crohn's disease.

Discovery of a novel series of N-hydroxypyridone derivatives protecting astrocytes against hydrogen peroxide-induced toxicity via improved mitochondrial functionality.

Astrocytes play a key role in brain homeostasis, protecting neurons against neurotoxic stimuli such as oxidative stress. Therefore, the neuroprotective therapeutics that enhance astrocytic functionality has been regarded as a promising strategy to reduce brain damage. We previously reported that ciclopirox, a well-known antifungal N-hydroxypyridone compound, protects astrocytes from oxidative stress by enhancing mitochondrial function. Using the N-hydroxypyridone scaffold, we have synthesized a series of cytoprotective derivatives. Mitochondrial activity assay showed that N-hydroxypyridone derivatives with biphenyl group have comparable to better protective effects than ciclopirox in astrocytes exposed to H2O2. N-hydroxypyridone derivatives, especially 11g, inhibited H2O2-induced deterioration of mitochondrial membrane potential and oxygen consumption rate, and significantly improved cell viability of astrocytes. The results indicate that the N-hydroxypyridone motif can provide a novel cytoprotective scaffold for astrocytes via enhancing mitochondrial functionality.

Synthesis and evaluation of (+)-decursin derivatives as inhibitors of the Wnt/ß-catenin pathway.

We synthesized (+)-decursin derivatives substituted with cinnamoyl- and phenyl propionyl groups originating from (+)-CGK062 and screened them using a cell-based assay to detect relative luciferase reporter activity. Of this series, compound 8b, in which a 3-acetoxy cinnamoyl group was introduced, most potently inhibited (97.0%) the Wnt/ß-catenin pathway. Specifically, compound 8b dose-dependently inhibited Wnt3a-induced expression of the ß-catenin response transcription (CRT) and increased ß-catenin degradation in HEK293 reporter cells. Furthermore, compound 8b suppressed expression of the downstream ß-catenin target genes cyclin D1 and c-myc and suppressed PC3 cell growth in a concentration-dependent manner.

A novel pyrazole derivative protects from ovariectomy-induced osteoporosis through the inhibition of NADPH oxidase.

Osteoclast cells (OCs) are differentiated from bone marrow-derived macrophages (BMMs) by activation of receptor activator of nuclear factor κB (NF-κB) ligand (RANKL). Activation of NADPH oxidase (Nox) isozymes is involved in RANKL-dependent OC differentiation, implicating Nox isozymes as therapeutic targets for treatment of osteoporosis. Here, we show that a novel pyrazole derivative, Ewha-18278 has high inhibitory potency on Nox isozymes. Blocking the activity of Nox with Ewha-18278 inhibited the responses of BMMs to RANKL, including reactive oxygen species (ROS) generation, activation of mitogen-activated protein (MAP) kinases and NF-κB, and OC differentiation. To evaluate the anti-osteoporotic function of Ewha-18278, the derivative was applied to estrogen-deficient ovariectomized (OVX) ddY mice. Oral administration of Ewha-18278 (10 mg/kg/daily, 4 weeks) into the mice recovered bone mineral density, trabecular bone volume, trabecular bone length, number and thickness, compared to control OVX ddY mice. Moreover, treatment of OVX ddY mice with Ewha-18278 increased bone strength by increasing cortical bone thickness. We provide that Ewha-18278 displayed Nox inhibition and blocked the RANKL-dependent cell signaling cascade leading to reduced differentiation of OCs. Our results implicate Ewha-18278 as a novel therapeutic agent for the treatment of osteoporosis.

Structure-activity relationship study of a series of novel oxazolidinone derivatives as IL-6 signaling blockers.

A series of oxazolidinone and indole derivatives were synthesized and evaluated as IL-6 signaling blockers by measuring the effects of these compounds on IL-6-induced luciferase expression in human hepatocarcinoma HepG2 cells transfected with p-STAT3-Luc. Among different compounds screened, compound 4d was emerged as the most potent IL-6 signaling blockers with IC50 value of 5.9 µM which was much better than (+)-Madindoline A (IC50=21 µM), a known inhibitor of IL-6.

A Novel Small-Molecule Inhibitor Targeting the IL-6 Receptor ß Subunit, Glycoprotein 130.

IL-6 is a major causative factor of inflammatory disease. Although IL-6 and its signaling pathways are promising targets, orally available small-molecule drugs specific for IL-6 have not been developed. To discover IL-6 antagonists, we screened our in-house chemical library and identified LMT-28, a novel synthetic compound, as a candidate IL-6 blocker. The activity, mechanism of action, and direct molecular target of LMT-28 were investigated. A reporter gene assay showed that LMT-28 suppressed activation of STAT3 induced by IL-6, but not activation induced by leukemia inhibitory factor. In addition, LMT-28 downregulated IL-6-stimulated phosphorylation of STAT3, gp130, and JAK2 protein and substantially inhibited IL-6-dependent TF-1 cell proliferation. LMT-28 antagonized IL-6-induced TNF-α production in vivo. In pathologic models, oral administration of LMT-28 alleviated collagen-induced arthritis and acute pancreatitis in mice. Based on the observation of upstream IL-6 signal inhibition by LMT-28, we hypothesized IL-6, IL-6Rα, or gp130 to be putative molecular targets. We subsequently demonstrated direct interaction of LMT-28 with gp130 and specific reduction of IL-6/IL-6Rα complex binding to gp130 in the presence of LMT-28, which was measured by surface plasmon resonance analysis. Taken together, our data suggest that LMT-28 is a novel synthetic IL-6 inhibitor that functions through direct binding to gp130.

Discovery of a novel series of benzimidazole derivatives as diacylglycerol acyltransferase inhibitors.

A novel series of benzimidazole derivatives was prepared and evaluated for their diacylglycerol acyltransferase (DGAT) inhibitory activity using microsome from rat liver. Among the newly synthesized compounds, furfurylamine containing benzimidazole carboxamide 10j showed the most potent DGAT inhibitory effect (IC(50)=4.4 µM) and inhibited triglyceride formation in HepG2 cells. Furthermore, compound 10j reduced body weight gain of Institute of Cancer Research mice on a high-fat diet and decreased levels of total triglyceride, total cholesterol, and LDL-cholesterol in the blood accompanied with a significant increase in HDL-cholesterol level.