Publications (51)212.78 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: To evaluate the significance of interleukin 4 (IL-4) in tumor development, we compared B16F10 melanoma growth in IL-4-overespressing transgenic mice (IL-4 mice) and non-transgenic mice. In IL-4 mice, reduced tumor volume and weight were observed when compared with those of non-transgenic mice. Significant activation of DNA binding activity of STAT6, phosphorylation of STAT6 as well as IL-4, IL-4Rα and p21 expression were found in the tumor tissues of IL-4 mice compared to non-transgenic mice. Higher expression of IL-4, STAT6 and p21 in human melanoma tissue compared to normal human skin tissue was also found. Higher expression of apoptotic protein such as cleaved caspase-3, cleaved caspase-8, cleaved caspase-9, Bax, p53 and p21, but lower expression levels of survival protein such as Bcl-2 were found in the tumor of IL-4 mice. In vitro study, we found that overexpression of IL-4 significantly inhibited SK-MEL-28 human melanoma cell and B16F10 murine melanoma cell growth via p21-mediated activation of STAT6 pathway as well as increased expression of apoptotic cell death proteins. Moreover, p21 knockdown with siRNA abolished IL-4 induced activation of STAT6 and expression of p53 and p21 accompanied with reduced IL-4 expression as well as melanoma cell growth inhibition. Therefore, these results showed that IL-4 overexpression suppressed tumor development through p21-mediated activation of STAT6 pathways in melanoma models.
- [Show abstract] [Hide abstract] ABSTRACT: Carfilzomib (CFZ) is a second-generation proteasome inhibitor drug approved for the treatment of multiple myeloma. Contrary to its excellent anti-myeloma activity, CFZ has shown only limited efficacy in patients with solid malignancies. This lack of efficacy has been attributed in part to rapid degradation of CFZ in the body, possibly hindering the ability of CFZ to access the proteasome target in solid tumors. We hypothesized that polymer micelles, a currently FDA-approved nanoparticle drug delivery formulation, may protect CFZ from metabolic degradation and thus expand the clinical utility of the drug as an anticancer agent. To test our hypothesis, we prepared CFZ-entrapped polymer micelle particles with various compositions and drug release profiles, and examined the extent of the CFZ metabolism in vitro using mouse liver homogenates. We also assessed the cytotoxic activities of the CFZ-entrapped micelle formulations in human cancer cell lines derived from B-lymphocytes (RPMI-8226) and the lung (H460). Our data indicated that polymer micelle-based formulations can improve metabolic stability and cytotoxic effects of CFZ compared to free CFZ in human cancer cell lines tested. Taken together, these results suggest that polymer micelles may have potential as a delivery system for CFZ with an extended therapeutic utility for non-hematological malignancies in the future. The American Society for Pharmacology and Experimental Therapeutics.
- [Show abstract] [Hide abstract] ABSTRACT: This study examined whether the relationship between cumulative thin-ideal media and body image disturbance is mediated by (1) cognitive variables, including beliefs about normative thinness and thinness prevalence and (2) affective variables, including dejection and agitation. Also, this study tested whether mediating effects would be different across cultures. Results revealed that perception about normative thinness mediated the relationship between thin-ideal media use and body image disturbance among both US and Korean participants and the effect was stronger for Korean participants. Thinness prevalence estimation did not mediate thin-ideal media use and body image disturbance in either Korean or US participants. Dejection was a statistically significant mediator for the relationship between thin-ideal media use and body image disturbance for both Korean and US participants, but no cultural differences were found. Agitation was also a statistically significant mediator for thin-ideal media use and body image disturbance, but only for Korean participants. Cultural differences in mediating effects were explained based on individualism and collectivism.
- [Show abstract] [Hide abstract] ABSTRACT: Duplex RNA harboring the 5'-terminal triphosphate RNA is hypothesized to not only execute selective gene silencing via RNA interference, but also induce type I interferon (IFN) through activation of the retinoic acid inducible gene I (RIG-I). We evaluated gene silencing efficacy of the shRNA containing 5'-triphosphate (3p-shRNA) targeting the hepatitis C virus (HCV) RNA genome in hepatic cells. Gene silencing efficacy of the 3p-shRNA was diminished due to the presence of the 5'-triphosphate moiety in shRNA, whereas the shRNA counterpart without 5'-triphosphate (HO-shRNA) showed a strong antiviral activity without significant induction of type I IFN in the cells. 3p-shRNA was observed to be a better activator of the RIG-I signaling than the HO-shRNA with an elevated induction of type I IFN in cells that express RIG-I. Taken together, we suggest that competition for the duplex RNA bearing 5'-triphosphate between RIG-I and RNA interference factors may compromise efficacy of selective gene silencing. Copyright © 2014. Published by Elsevier Inc.
- [Show abstract] [Hide abstract] ABSTRACT: This paper focuses on analysing college women’s narratives to discover their interpretations of thin ideals and dieting experiences and to compare cultural differences between the USA and Korea. Narrative analysis revealed that US women and Korean women have a different understanding of thin ideals. Both groups experienced social comparisons, social pressure to be thin, and emotional distress regarding appearance. Similarly, they revealed their emotional fluctuations associated with changes in weight. However, there were cultural differences in both groups’ ultimate goals for weight control. Consequently, this study suggests that feelings towards weight control have culturally grounded implications. Future directions are discussed.
- [Show abstract] [Hide abstract] ABSTRACT: Remarkable successes with the FDA-approved proteasome inhibitors bortezomib (Velcade®) and carfilzomib (Kyprolis®) have proved that the proteasome is an effective target for the treatment of multiple myeloma. In other hematological malignancies, however, clinical trials of proteasome-targeting drugs have shown generally disappointing results to date. Additionally, existing proteasome inhibitors have significant issues with toxicity, poor response rate, and the emergence of resistance for many patients. A new generation of small-molecule therapies specifically targeting the immunoproteasome may have the potential to overcome the drawbacks of bortezomib and carfilzomib in multiple myeloma and to bring significant benefits of proteasome inhibitor therapies to many more patients. In this article, we describe the potential of the immunoproteasome as a therapeutic target for hematological malignancies and the recent progress in the development of useful immunoproteasome inhibitors.
- [Show abstract] [Hide abstract] ABSTRACT: Mammalian genomes encode seven catalytic proteasome subunits, namely β1c, β2c, β5c (assembled into constitutive 20S proteasome core particles), β1i, β2i, β5i (incorporated into immunoproteasomes) and the thymoproteasome-specific subunit, β5t. Extensive research in the past decades has yielded numerous potent proteasome inhibitors including compounds currently used in the clinic to treat multiple myeloma and mantle cell lymphoma. Proteasome inhibitors that selectively target combinations of β1c/β1i, β2c/β2i or β5c/β5i are available, yet ligands truly selective for a single proteasome activity are scarce. In this work we report the development of cell-permeable β1i as well as β5i selective inhibitors, which outperform existing leads in terms of selectivity and/or potency. These compounds are the result of a rational design strategy using known inhibitors as starting points and introducing structural features according to the X-ray structures of the murine constitutive and immunoproteasome 20S core particles.
- [Show abstract] [Hide abstract] ABSTRACT: Novel withanolide chemical genetic probes identify the in vivo binding target of withaferin A, which is the intermediate filament type III protein vimentin. In addition, a withanolide-based small molecule screening method screens drug candidates that target intermediate filament type III proteins. The method includes introducing a tagged linker covalently bonded to the withanolide molecule to form a withanolide probe. Better or alternative small molecule compounds as potential drug candidates can be generated based on their likely affinity for the determined binding site in vimentin. The affinity labeled withanolide can also be used to find intermediate filament-associated proteins using chemical proteomics by extracting proteins from cells that were exposed to withanolide-biotin analog. The withanolide probes can be used to monitor expression of vimentin, in tumor samples or other diseased tissues. Withaferin analogs can be used as a treatment for diverse vimentin-associated disorders, such as cancers, angiofibrotic diseases, and chronic inflammation.
- [Show abstract] [Hide abstract] ABSTRACT: The proteasome is a key regulator of cellular protein homeostasis and is a clinically validated anticancer target. The immunoproteasome, a subtype of proteasome expressed mainly in hematopoietic cells, was initially recognized for its role in antigen presentation during the immune response. Recently, the immunoproteasome has been implicated in several disease conditions including cancer and autoimmune disorders, but many of the factors contributing to these pathological processes remain unknown. In particular, the codon 60 polymorphism of the PSMB9 gene encoding the β1i immunoproteasome catalytic subunit has been investigated in the context of a variety of diseases. Despite this, previous studies have so far reported inconsistent findings regarding the impact of this polymorphism on proteasome activity. Thus, we set out to investigate the impact of the PSMB9 codon 60 polymorphism on the expression and activity of the β1i immunoproteasome subunit in a panel of human cancer cell lines. The β1i-selective fluorogenic substrate Acetyl-Pro-Ala-Leu-7-amino-4-methylcoumarin was used to specifically measure β1i catalytic activity. Our results indicate that the codon 60 Arg/His polymorphism does not significantly alter the expression and activity of β1i among the cell lines tested. Additionally, we also examined the expression of β1i in clinical samples from colon and pancreatic cancer patients. Our immunohistochemical analyses showed that ∼70% of clinical colon cancer samples and ∼53% of pancreatic cancer samples have detectable β1i expression. Taken together, our results indicate that the β1i subunit of the immunoproteasome is frequently expressed in colon and pancreatic cancers but that the codon 60 genetic variants of β1i display similar catalytic activities and are unlikely to contribute to the significant inter-cell-line and inter-individual variabilities in the immunoproteasome activity.
- [Show abstract] [Hide abstract] ABSTRACT: The purpose of this work was to optimize the structure of codrugs for extended delivery across microneedle treated skin. Naltrexone, the model compound was linked with diclofenac, a nonspecific cyclooxygenase inhibitor to enhance the pore lifetime following microneedle treatment and develop a 7 day transdermal system for naltrexone. Four different codrugs of naltrexone and diclofenac were compared in terms of stability and solubility. Transdermal flux, permeability and skin concentration of both parent drugs and codrugs were quantified to form a structure permeability relationship. The results indicated that all codrugs bioconverted in the skin. The degree of conversion was dependent on the structure, phenol linked codrugs were less stable compared to the secondary alcohol linked structures. The flux of naltrexone across microneedle treated skin and the skin concentration of diclofenac were higher for the phenol linked codrugs. The polyethylene glycol link enhanced solubility of the codrugs, which translated into flux enhancement. The current studies indicated that formulation stability of codrugs and the flux of naltrexone can be enhanced via structure design optimization. The polyethylene glycol linked naltrexone diclofenac codrug is better suited for a 7 day drug delivery system both in terms of stability and drug delivery.
- [Show abstract] [Hide abstract] ABSTRACT: Over the years, the proteasome has been extensively investigated due to its crucial roles in many important signaling pathways and its implications in diseases. Two proteasome inhibitors-bortezomib and carfilzomib-have received FDA approval for the treatment of multiple myeloma, thereby validating the proteasome as a chemotherapeutic target. As a result, further research efforts have been focused on dissecting the complex biology of the proteasome to gain the insight required for developing next-generation proteasome inhibitors. It is clear that chemical probes have made significant contributions to these efforts, mostly by functioning as inhibitors that selectively block the catalytic activity of proteasomes. Analogues of these inhibitors are now providing additional tools for visualization of catalytically active proteasome subunits, several of which allow real-time monitoring of proteasome activity in living cells as well as in in vivo settings. These imaging probes will provide powerful tools for assessing the efficacy of proteasome inhibitors in clinical settings. In this review, we will focus on the recent efforts towards developing imaging probes of proteasomes, including the latest developments in immunoproteasome-selective imaging probes.
- [Show abstract] [Hide abstract] ABSTRACT: Covering: 1992 to 2012The initial enthusiasm following the discovery of a pharmacologically active natural product is often fleeting due to the poor prospects for its ultimate clinical application. Despite this, the ever-changing landscape of modern biology has a constant need for molecular probes that can aid in our understanding of biological processes. After its initial discovery by Bristol-Myers Squibb as a microbial anti-tumor natural product, epoxomicin was deemed unfit for development due to its peptide structure and potentially labile epoxyketone pharmacophore. Despite its drawbacks, epoxomicin's pharmacophore was found to provide unprecedented selectivity for the proteasome. Epoxomicin also served as a scaffold for the generation of a synthetic tetrapeptide epoxyketone with improved activity, YU-101, which became the parent lead compound of carfilzomib (Kyprolis™), the recently approved therapeutic agent for multiple myeloma. In this era of rational drug design and high-throughput screening, the prospects for turning an active natural product into an approved therapy are often slim. However, by understanding the journey that began with the discovery of epoxomicin and ended with the successful use of carfilzomib in the clinic, we may find new insights into the keys for success in natural product-based drug discovery.
- [Show abstract] [Hide abstract] ABSTRACT: Peptide nucleic acids (PNAs) that bind to complementary nucleic acid sequences with extraordinarily high affinity and sequence specificity can be used as antisense oligonucleotides against microRNAs, namely antagomir PNAs. However, methods for efficient cellular delivery must be developed for effective use of PNAs as therapeutic agents. Here, we demonstrate that antagomir PNAs can be delivered to hepatic cells by complementary DNA oligonucleotide and cationic liposomes containing galactosylated ceramide and a novel cationic lipid, DMKE (O,O'-dimyristyl-N-lysyl glutamate), through glycoprotein-mediated endocytosis. An antagomir PNA was designed to target miR-122, which is required for translation of the hepatitis C virus (HCV) genome in hepatocytes, and was hybridized to a DNA oligonucleotide for complexation with cationic liposome. The PNA-DNA hybrid molecules were efficiently internalized into hepatic cells by complexing with the galactosylated cationic liposome in vitro. Galactosylation of liposome significantly enhanced both lipoplex cell binding and PNA delivery to the hepatic cells. After 4-h incubation with galactosylated lipoplexes, PNAs were efficiently delivered into hepatic cells and HCV genome translation was suppressed more than 70% through sequestration of miR-122 in cytoplasm. PNAs were readily released from the PNA-DNA hybrid in the low pH environment of the endosome. The present study indicates that transfection of PNA-DNA hybrid molecules using galactosylated cationic liposomes can be used as an efficient non-viral carrier for antagomir PNAs targeted to hepatocytes.
- [Show abstract] [Hide abstract] ABSTRACT: The ubiquitin-proteasome system (UPS) plays a vital role in maintaining protein homeostasis and regulating numerous cellular processes. The proteasome, a multi-protease complex, is the key component of the UPS that has been validated as a therapeutic target by the FDA's approval of bortezomib and carfilzomib. These proteasome inhibitor drugs have substantially improved outcomes in patients with hematological malignancies and are currently being investigated for other types of cancer as well as several other diseases. These approved proteasome inhibitors target the catalytic activity of both the constitutive proteasome and immunoproteasome indiscriminately and their inhibitory effects on the constitutive proteasome in normal cells are believed to contribute to unwanted side effects. In addition, selective immunoproteasome inhibition has been proposed to have unique effects on other diseases, including those involving aberrant immune function. Initially recognized for its role in the adaptive immune response, the immunoproteasome is often upregulated in disease states such as inflammatory diseases and cancer, suggesting functions beyond antigen presentation. In an effort to explore the immunoproteasome as a potential therapeutic target in these diseases, the development of immunoproteasome-specific inhibitors has become the focus of recent studies. Owing to considerable efforts by both academic and industry groups, immunoproteasome-selective inhibitors have now been identified and tested against several disease models. These inhibitors also provide a valuable set of chemical tools for investigating the biological function of the immunoproteasome. In this review, we will focus on the recent efforts towards the development of immunoproteasome-selective inhibitors.
- [Show abstract] [Hide abstract] ABSTRACT: The cover picture shows a fluorescent image of the immunoproteasome captured in living cells by using LKS01‐B650, an immunoproteasome‐selective activity‐based fluorescent probe. The image at the bottom shows the binding mode of LKS01‐B650 to the β5i‐catalytic subunit of the immunoproteasome. Considering recent studies that suggest an important role of the immunoproteasome in multiple disease states, this imaging probe could help us to understand immunoproteasome functions better and to explore its therapeutic potential. On p. 1899 ff., W. Lee, K.‐B. Kim et al. describe the structure‐based design, synthesis and characterization of a near‐infra‐red fluorescent probe that targets the immunoproteasome subunit β5i. Cell‐based binding studies, in‐gel fluorescence and competition assays all clearly demonstrate the ability of this probe to visualize the immunoproteasome catalytic subunit LMP7/β5i in living cells, thus providing a valuable tool for immunoproteasome biology. The cover picture was prepared by Chitra Saini.
- [Show abstract] [Hide abstract] ABSTRACT: To evaluate the significance of C–C chemokine receptor type 5 (CCR5) in lung tumor development, we compared carcinogen-induced tumor growth in CCR5 knockout (CCR5−/−) mice and wild-type (CCR5+/+) mice. CCR5−/− mice showed reduced urethane (1g/kg)-induced tumor incidence when compared with those of CCR5+/+ mice. We investigated the activation of nuclear factor-kappaB/STAT3 since these are implicated transcription factors in the regulation of genes involving tumor growth. Significant inhibition of DNA-binding activity of nuclear factor-kappaB and STAT3, and the translocation of p50 and p65 into the nucleus and the phosphorylation of IĸB were found in the lungs of CCR5−/− mice compared with the lungs of CCR5+/+ mice. Expression of apoptotic protein such as cleaved caspase-3, cleaved PARP and Bax was elevated, whereas the expression levels of survival protein such as Bcl-2 and cIAP1 was decreased in the lungs of CCR5−/− mice. Interestingly, we found that the level of monocyte chemoattractant protein-1 (MCP-1), a tumor growth–promoting cytokine, was significantly reduced in the lung tumor tissue and blood of CCR5−/− mice compared with the level in CCR5+/+ mice. In addition, CCR5 small interfering RNA (siRNA) and inhibitor of MCP-1 blocked lung cancer cell growth, which was abolished by the addition of MCP-1 protein in cultured lung cancer cells. Moreover, inactivation of CD8+ cytotoxic T cell and dendritic cells was significantly increased in the blood, lung tumors and spleens of CCR5−/− mice compared with that of CCR5+/+ mice. Therefore, these results showed that CCR5 deficiency suppressed lung tumor development through the inhibition of nuclear factor-kappaB/STAT3 pathways and the downregulation of MCP-1 in the carcinogen-induced lung tumor model.
- [Show abstract] [Hide abstract] ABSTRACT: Carfilzomib is a novel class of peptidyl epoxyketone proteasome inhibitor and has demonstrated promising activity in multiple clinical trials to treat patients with multiple myeloma and other types of cancers. Here, we investigated molecular mechanisms underlying acquired resistance to carfilzomib and a potential strategy to restore cellular sensitivity to carfilzomib. H23 and DLD-1 cells (human lung and colon adenocarcinoma cell lines) with acquired resistance to carfilzomib displayed marked cross-resistance to YU-101, a closely related proteasome inhibitor, and paclitaxel, a known substrate of Pgp. However, carfilzomib-resistant cells remained sensitive to bortezomib, a clinically used dipeptide with boronic acid pharmacophore. In accordance with these observations, carfilzomib-resistant H23 and DLD-1 cells showed marked upregulation of P-glycoprotein (Pgp) as compared to their parental controls, and coincubation with verapamil, a Pgp inhibitor, led to an almost complete restoration of cellular sensitivity to carfilzomib. These results indicate that Pgp upregulation plays a major role in the development of carfilzomib resistance in these cell lines. In developing a potential strategy to overcome carfilzomib resistance, we as a proof of concept prepared a small library of peptide analogues derived from the peptide backbone of carfilzomib and screened these molecules for their activity to restore carfilzomib sensitivity when cotreated with carfilzomib. We found that compounds as small as dipeptides are sufficient in restoring carfilzomib sensitivity. Taken together, we found that Pgp upregulation plays a major role in the development of resistance to carfilzomib in lung and colon adenocarcinoma cell lines and that small peptide analogues lacking the pharmacophore can be used as agents to reverse acquired carfilzomib resistance. Our findings may provide important information in developing a potential strategy to overcome drug resistance.
- [Show abstract] [Hide abstract] ABSTRACT: The discovery of NF-κB signaling pathways has greatly enhanced our understanding of inflammatory and immune responses. In the canonical NF-κB pathway, the proteasomal degradation of IκBα, an inhibitory protein of NF-κB, is widely accepted to be a key regulatory step. However, contradictory findings have been reported as to whether the immunoproteasome plays an obligatory role in the degradation of IκBα and activation of the canonical NF-κB pathway. Such results were obtained mainly using traditional gene deletion strategies. Here, we have revisited the involvement of the immunoproteasome in the canonical NF-κB pathway using small molecule inhibitors of the immunoproteasome, namely UK-101 and LKS01 targeting β1i and β5i, respectively. H23 and Panc-1 cancer cells were pretreated with UK-101, LKS01 or epoxomicin (a prototypic inhibitor targeting both the constitutive proteasome and immunoproteasome). We then examined whether these pretreatments lead to any defect in activating the canonical NF-κB pathway following TNFα exposure by monitoring the phosphorylation and degradation of IκBα, nuclear translocation of NF-κB proteins and DNA binding and transcriptional activity of NF-κB. Our results consistently indicated that there is no defect in activating the canonical NF-κB pathway following selective inhibition of the immunoproteasome catalytic subunits β1i, β5i or both using UK-101 and LKS01, in contrast to epoxomicin. In summary, our current results using chemical genetic approaches strongly support that the catalytic activity of the immunoproteasome subunits β1i and β5i is not required for canonical NF-κB activation in lung and pancreatic adenocarcinoma cell line models.
- [Show abstract] [Hide abstract] ABSTRACT: The type III intermediate filaments (IFs) are essential cytoskeletal elements of mechanosignal transduction and serve critical roles in tissue repair. Mice genetically deficient for the IF protein vimentin (Vim−/−) have impaired wound healing from deficits in myofibroblast development. We report a surprising finding made in Vim−/− mice that corneas are protected from fibrosis and instead promote regenerative healing after traumatic alkali injury. This reparative phenotype in Vim−/− corneas is strikingly recapitulated by the pharmacological agent withaferin A (WFA), a small molecule that binds to vimentin and down-regulates its injury-induced expression. Attenuation of corneal fibrosis by WFA is mediated by down-regulation of ubiquitin-conjugating E3 ligase Skp2 and up-regulation of cyclin-dependent kinase inhibitors p27Kip1 and p21Cip1. In cell culture models, WFA exerts G2/M cell cycle arrest in a p27Kip1- and Skp2-dependent manner. Finally, by developing a highly sensitive imaging method to measure corneal opacity, we identify a novel role for desmin overexpression in corneal haze. We demonstrate that desmin down-regulation by WFA via targeting the conserved WFA-ligand binding site shared among type III IFs promotes further improvement of corneal transparency without affecting cyclin-dependent kinase inhibitor levels in Vim−/− mice. This dissociates a direct role for desmin in corneal cell proliferation. Taken together, our findings illuminate a previously unappreciated pathogenic role for type III IF overexpression in corneal fibrotic conditions and also validate WFA as a powerful drug lead toward anti-fibrosis therapeutic development.
Seoul National UniversitySŏul, Seoul, South Korea
Konkuk UniversitySŏul, Seoul, South Korea
The Ohio State UniversityColumbus, Ohio, United States
New Haven, Connecticut, United States
- Department of Molecular, Cellular and Developmental Biology
University of Kentucky
Lexington, KY, United States
- Department of Pharmaceutical Sciences