Ky-Youb Nam

Adenylyl cyclase-associated protein 1 is a receptor for human resistin and mediates inflammatory actions of human monocytes.

Human resistin is a cytokine that induces low-grade inflammation by stimulating monocytes. Resistin-mediated chronic inflammation can lead to obesity, atherosclerosis, and other cardiometabolic diseases. Nevertheless, the receptor for human resistin has not been clarified. Here, we identified adenylyl cyclase-associated protein 1 (CAP1) as a functional receptor for human resistin and clarified its intracellular signaling pathway to modulate inflammatory action of monocytes. We found that human resistin directly binds to CAP1 in monocytes and upregulates cyclic AMP (cAMP) concentration, protein kinase A (PKA) activity, and NF-κB-related transcription of inflammatory cytokines. Overexpression of CAP1 in monocytes enhanced the resistin-induced increased activity of the cAMP-dependent signaling. Moreover, CAP1-overexpressed monocytes aggravated adipose tissue inflammation in transgenic mice that express human resistin from their monocytes. In contrast, suppression of CAP1 expression abrogated the resistin-mediated inflammatory activity both in vitro and in vivo. Therefore, CAP1 is the bona fide receptor for resistin leading to inflammation in humans.

Development of cyclic peptomer inhibitors targeting the polo-box domain of polo-like kinase 1.

The polo-box domain (PBD) of polo-like kinase 1 (Plk1) is essentially required for the function of Plk1 in cell proliferation. The availability of the phosphopeptide-binding pocket on PBD provides a unique opportunity to develop novel protein-protein interaction inhibitors. Recent identification of a minimal 5-residue-long phosphopeptide, PLHSpT, as a Plk1 PBD-specific ligand has led to the development of several peptide-based inhibitors, but none of them is cyclic peptide. Through the combination of single-peptoid mimics and thio-ether bridged cyclization, we successfully demonstrated for the first time two cyclic peptomers, PL-116 and PL-120, dramatically improved the binding affinity without losing mono-specificity against Plk1 PBD in comparison with the linear parental peptide, PLHSpT. These cyclic peptomers could serve as promising templates for future drug designs to inhibit Plk1 PBD.

De novo design and synthesis of ultra-short peptidomimetic antibiotics having dual antimicrobial and anti-inflammatory activities.

Background Much attention has been focused on the design and synthesis of potent, cationic antimicrobial peptides (AMPs) that possess both antimicrobial and anti-inflammatory activities. However, their development into therapeutic agents has been limited mainly due to their large size (12 to 50 residues in length) and poor protease stability. Methodology/Principal Findings In an attempt to overcome the issues described above, a set of ultra-short, His-derived antimicrobial peptides (HDAMPs) has been developed for the first time. Through systematic tuning of pendant hydrophobic alkyl tails at the N(π)- and N(τ)-positions on His, and the positive charge of Arg, much higher prokaryotic selectivity was achieved, compared to human AMP LL-37. Additionally, the most potent HDAMPs showed promising dual antimicrobial and anti-inflammatory activities, as well as anti–methicillin-resistant Staphylococcus aureus (MRSA) activity and proteolytic resistance. Our results from transmission electron microscopy, membrane depolarization, confocal laser-scanning microscopy, and calcein-dye leakage experiments propose that HDAMP-1 kills microbial cells via dissipation of the membrane potential by forming pore/ion channels on bacterial cell membranes. Conclusion/Significance The combination of the ultra-short size, high-prokaryotic selectivity, potent anti-MRSA activity, anti-inflammatory activity, and proteolytic resistance of the designed HDAMP-1, -3, -5, and -6 makes these molecules promising candidates for future antimicrobial therapeutics.

Investigation of some amino acids conformations at the interface of binary mixture using the solvation free energy density model

Abstract The behavior of terminally blocked amino acids, N -acetyl alanine amide (NAA), N -acetyl leucine amide (NAL), and N -acetyl glutatmine amide (NAQ) at the 1-octanol/water continuum interface was investigated by Monte Carlo simulation with the solvation free energy density (SFED) calculation method. All the model amino acids have free energy minimum near the interface. These amino acids can have various conformations such as α-helix, β-sheet, and C 7−eq , however the minimum energy conformations are obtained as α-helix for all the model amino acids at the interface region.

The Small Molecule AU14022 Promotes Colorectal Cancer Cell Death via p53-mediated G2/M-phase Arrest and Mitochondria-mediated Apoptosis†

The p53 tumor suppressor plays critical roles in cell cycle regulation and apoptotic cell death, with its activation capable of sensitizing cancer cells to radiotherapy or chemotherapy. To identify small molecules that induce apoptosis via increased p53 transcriptional activity, we used a novel in‐house library containing 96 small‐molecule compounds. Using a cell‐based screening method with a p53‐responsive luciferase‐reporter assay system involving benzoxazole derivatives, we found that AU14022 administration significantly increased p53 transcriptional activity in a concentration‐dependent manner. Treatment with AU14022 increased p53 protein expression, p53 Ser15 phosphorylation, p53‐mediated expression of downstream target genes, and apoptosis in p53‐wild‐type HCT116 human colon cancer cells, but not in p53‐knockout HCT116 cells. Additionally, p53‐wild‐type HCT116 cells treated with AU14022 exhibited mitochondrial dysfunction, including modulated expression of B‐cell lymphoma‐2 family proteins and cytochrome c release. Combination treatment with AU14022 and ionizing radiation (IR) synergistically induced apoptosis as compared with IR or AU14022 treatment alone, with further investigation demonstrating that cell cycle progression was significantly arrested at the G2/M phase following AU14022 treatment. Furthermore, in a mouse p53‐wild‐type HCT116 colon cancer xenograft model, combined treatment with AU14022 and IR inhibited tumor growth more effectively than radiation alone. Therefore, AU14022 treatment induced apoptosis through p53‐mediated cell cycle arrest involving mitochondrial dysfunction, leading to enhanced radiosensitivity in colon cancer cells. These results provide a basis for further assessments of AU14022 as a promising anticancer agent.

Identification of chalcones as potent and selective PDE5A1 inhibitors.

Chalcones have an affinity for many receptors, enzymes, and transcription factors as flavonoid analogues. Their most studied pharmacological action is that of vasodilatation due to inhibition of phosphodiesterase 5A1 (PDE5A1). To this end, we have established a recursive partitioning model with 3 chemical descriptors for the prediction of compounds that can inhibit PDE5A1. This model was able to predict active compounds with an accuracy of 82.8%. Compound 4 was found to be a potent and selective inhibitor, with a relatively low IC(50) value. The binding mechanism of this compound was also investigated through molecular docking studies.

Intra ion–ion interactions in aqueous solution: β-alanine zwitterion and 1,2-ethenediammonium

Abstract To illuminate the behavior of ion pairs in aqueous solution, both ab initio SCRF MO calculation and MD simulation were performed. The free energy difference of each system was decomposed into contributing components in order to investigate the role of the water in aqueous solution. In aqueous solution, the dominant component contributing to the ion pair stability, is not a solute–solute interaction, but an ion pair–water interaction and the energy change that originated from the rearrangement of the water molecules around the ion pair.

Microscopic hematuria is a risk factor of incident chronic kidney disease in the Korean general population: a community-based prospective cohort study

Background Although asymptomatic microscopic hematuria (MH) is a common finding in clinical practice, its long-term outcome remains unknown. Aim This study evaluated the clinical implication of MH in the general population using a large-scale long-term longitudinal cohort database. Methods This study included 8719 participants from the Korean Genome and Epidemiology Study between 2001 and 2014. MH was defined as ≥5 red blood cells per high-power field in random urinalysis without evidence of pyuria. The primary study outcome measure was incident chronic kidney disease (CKD), defined as estimated glomerular filtration rate <60 ml min-1⋅1.73⋅m-2. Results During a median follow-up of 11.7 years, CKD occurred in 677 (7.8%) subjects. In Cox regression after adjustment for multiple confounders, subjects with MH had a significantly higher risk of incident CKD than those without [hazard ratio (HR) 1.45, 95% confidence interval (CI) 1.12-1.87; P = 0.005]. Isolated MH without proteinuria was also a risk factor of incident CKD (HR 1.37, 95% CI 1.04-1.79; P = 0.023) and the risk was further increased in MH with concomitant proteinuria (HR 5.41, 95% CI 2.54-11.49; P < 0.001). In propensity score matching analysis after excluding subjects with proteinuria, multi-variable stratified Cox regression analysis revealed that subjects with isolated MH had a significantly higher risk of incident CKD than those without (HR 1.83, 95% CI 1.14-2.94; P = 0.012). Conclusion The presence of MH is associated with an increased risk of incident CKD in the general population. Therefore, attentive follow-up is warranted in persons with MH for early detection of CKD.

Abstract 941: Discovery of novel VEGFR2 and Raf-1 kinase inhibitorsuppressing MAPK signaling pathway in K-Ras mutant cancer cell-lines.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Introduction: Signal transduction in the Ras-Raf-MEK-ERK (MAPK) pathway plays a key role in cell survival, growth and proliferation. The pathway is controlled by extracellular signals through receptor tyrosine kinases (RTK) and is activated by oncogenic mutations in many types of cancer. The B-Raf mutants are found in various cancers, such as melanoma, colorectal, ovarian, and prostate cancer. The Ras mutants are also found in various carcinomas including colon cancer, pancreatic cancer, non-small-cell lung cancer, and liver cancer. The mutated K-Ras gene sends continuous signals to the colorectal cancer cells, telling them to grow independent of the way ERBITUX blocks the EGFR growth signals. Especially, over 90% of detected mutations in B-Raf are a V600E which leads to constitutive kinase activity 500-fold greater than B-Raf wild type and correlates with increased malignancy. Vascular endothelial growth factor (VEGF) and its receptors have been implicated in the angiogenesis that is essential for growth and metastasis of solid tumors. Since formation of solid tumors are angiogenesis dependent, several strategies have been developed to inhibit VEGF signal transduction as part of anticancer therapy. The first VEGFR2 and Raf-1 inhibitor to enter clinical development was the multikinase inhibitor SORAFENIB, which is now approved for the treatment of patients with advanced renal cell carcinoma. More potent dual inhibitors against VEGFR2 and Raf-1 may be beneficial for patients suffering from various tumors. In this study, some of rational-designed compounds were synthesized and carried out the in vitro and in vivo studies to find more efficient VEGFR2 and Raf-1 inhibitors. Methods: About two hundreds of compounds were designed and synthesized. in vitro assays and in vivo studies were performed to characterize the potential of VEGFR2 and Raf-1 inhibitors for solid tumors. Results: Compound UI-162 showed strong kinase inhibition against VEGFR2 (12 nM), B-Raf V600E mutant (0.2 nM), B-Raf wildtype (2.0 nM) and Raf-1(0.6 nM). The compound showed good inhibitory effect in against malignant cells expressing K-Ras or B-Raf V600E mutant type of cell-line (SK-MEL-2 GI50: 133 nM / HCT-116 GI50: 229 nM / MDA-MB231 GI50: 278 nM / A375P GI50: 51 nM / HT29 GI50: 40 nM / COLO 205 GI50: 12 nM, respectively). In mechanism studies, the phosphorylation of MEK and ERK were suppressed by the UI-162 compound in HCT-116 cell-line. In addition, paradoxical effects were not detected compared with VEMURAFENIB. The compound had also a good anti-proliferative activity against HUVEC and showed a good oral bioavailability. Conclusions: The results of in vitro and in vivo studies suggests that dual inhibition of VEGFR2 and Raf-1 may provide strong antitumor efficacy and that UI-162 is a promising candidate for the treatment of various human cancers harboring the K-Ras and B-Raf V600E mutation. Citation Format: Seung Yong Kim, Younho Lee, Hyungtae Bang, Kihwan Eum, Sungpyo Hong, Ky-Youb Nam, Nam Song Choi, Ju Hee Kang, Hara Kang, Kil Won Kim, Michael Lee, Soon Kil Ahn. Discovery of novel VEGFR2 and Raf-1 kinase inhibitorsuppressing MAPK signaling pathway in K-Ras mutant cancer cell-lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 941. doi:10.1158/1538-7445.AM2013-941

Abstract 1803: Discovery of novel B-Raf kinase inhibitor with potent orally anticancer activity

Introduction: The B-Raf, one of serine/threonine kinase, is related to the Ras-Raf-MEK-ERK (MAPK) signal transduction. The signaling pathway plays a key role in cell survival, growth and proliferation. The B-Raf mutants are found in various cancer patients, such as melanoma, papillary thyroid, cisplatin-refractory testicular cancer, colorectal, ovarian, and prostate cancer. Especially, over 90% of detected mutations in B-Raf are a V600E which leads to constitutive kinase activity 500-fold greater than B-Raf wild type and correlates with increased malignancy and decreased response the chemotherapy. There are currently numerous efforts to develop therapeutic agents to target B-Raf or its downstream kinases. The first Raf inhibitor to enter clinical development was the multi-kinase inhibitor Nexavar (sorafenib tosylate), which is now approved for the treatment of patients with advanced renal cell carcinoma. However, the broad selectivity profile of this inhibitor makes it unsuitable for proof of concept evaluation of Raf kinase inhibition in tumors. Recently, more selective Raf inhibitors have been disclosed, and chemical inhibition of B-Raf enzymatic activity using these compounds can result in diminished proliferation and survival of tumor cells. However, very limited drug candidates with in vivo data have been published for B-Raf V600E . In this study, some of rational-designed compounds were synthesized and carried out the in vitro and in vivo studies to investigate more efficient B-Raf V600E inhibitors. Methods: About two hundreds of compounds were designed and synthesized. The in vitro assays and in vivo studies were performed to characterize the potential of B-Raf V600E inhibitors for solid tumors. Results: Compound UAI-201 had good inhibition effect in malignant cells expressing B-Raf V600E mutant type of cell-line (A375P GI 50 : 6nM / HT29 GI 50 : 5nM / COLO 205 GI 50 : 1nM), selectively. And the compound showed better tumor growth inhibition in xenograft mouse models (TGI(%): 61.87, 10mg/kg, PO, BID x 2weeks) compared with known inhibitors. In mechanism studies, the phosphorylation levels of MEK and ERK were effectively decreased by the UAI-201 compound in A375P cell-line. In addition, paradoxical effects were not detected compared with known compound. The compound had no toxicity in normal cell-line(HS-27 cell) and did not inhibit several CYP P450s. And also, UAI-201 showed good oral bioavailability with an acceptable clearance and half-life pharmacokinetic properties. Conclusions: The in vitro and in vivo studies of UAI-201 indicate that it is safe and efficacious, and suggests that it may good drug candidate for the preclinical study. Preclinical study our candidate, UAI-201, was started and the results will be disclosed in the near future. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1803. doi:1538-7445.AM2012-1803