Dong-Jin Hwang - Academia.edu (original) (raw)

Papers by Dong-Jin Hwang

Antimitotics that target tubulin are among the most useful chemotherapeutic drugs, but their clin... more Antimitotics that target tubulin are among the most useful chemotherapeutic drugs, but their clinical activity is often limited by the development of multidrug resistance. We recently discovered the novel small-molecule DJ101 as a potent and metabolically stable tubulin inhibitor that can circumvent the drug efflux pumps responsible for multidrug resistance of existing tubulin inhibitors. In this study, we determined the mechanism of action of this drug. The basis for its activity was illuminated by solving the crystal structure of DJ101 in complex with tubulin at a resolution of 2.8Å. Investigations of the potency of DJ101 in a panel of human metastatic melanoma cell lines harboring major clinically relevant mutations defined IC50 values of 7–10 nmol/L. In cells, DJ101 disrupted microtubule networks, suppressed anchorage-dependent melanoma colony formation, and impaired cancer cell migration. In melanoma-bearing mice, DJ101 administration inhibited tumor growth and reduced lung met...

Raw data from pharmacological profile screening for DJ101 performed by DicoverX using its Safety4... more Raw data from pharmacological profile screening for DJ101 performed by DicoverX using its Safety47 panel.

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Captions for supporting data and detailed methods for chemical synthesis and standard biochemical... more Captions for supporting data and detailed methods for chemical synthesis and standard biochemical assays

S5: UT-155 prevents nuclear localization of AR and AR v567es. S6: UT-155 binds to AR AF-1 domain.... more S5: UT-155 prevents nuclear localization of AR and AR v567es. S6: UT-155 binds to AR AF-1 domain. S7: Results from microarray with SARDs.S8: UT-155 inhibits transactivation of AD1 and D567es AR transactivation. Metabolism properties of SARDs.

S1: SARDs inhibit AR mutant activity. S2: UT-155-dependent degradation is selective to the AR. S3... more S1: SARDs inhibit AR mutant activity. S2: UT-155-dependent degradation is selective to the AR. S3: UT-155 degrades wildtype and Y267 phospho mutant ARs. S4. UT-155 inhibits AR ABCD and AR-V7 induced activity.

Androgen receptor (AR) mediates the growth of prostate cancer throughout its course of developmen... more Androgen receptor (AR) mediates the growth of prostate cancer throughout its course of development, including in abnormal splice variants (AR-SV)-driven advanced stage castration-resistant disease. AR stabilization by androgens makes it distinct from other steroid receptors, which are typically ubiquitinated and degraded by proteasomes after ligand binding. Thus, targeting AR in advanced prostate cancer requires the development of agents that can sustainably degrade variant isoforms for effective therapy. Here we report the discovery and characterization of potent selective AR degraders (SARD) that markedly reduce the activity of wild-type and splice variant isoforms of AR at submicromolar doses. Three SARDs (UT-69, UT-155, and (R)-UT-155) bind the amino-terminal transcriptional activation domain AF-1, which has not been targeted for degradation previously, with two of these SARD (UT-69 and UT-155) also binding the carboxy-terminal ligand binding domain. Despite different mechanisms...

Resistance index values of DJ101 measured in drug sensitive PC-3 and DU-145 and their correspondi... more Resistance index values of DJ101 measured in drug sensitive PC-3 and DU-145 and their corresponding taxane resistant sublines.

NCI-60 screening data for DJ101

Endocrinology, 2010

Glucocorticoids are the most widely used antiinflammatory drugs in the world. However, prolonged ... more Glucocorticoids are the most widely used antiinflammatory drugs in the world. However, prolonged use of glucocorticoids results in undesirable side effects such as muscle wasting, osteoporosis, and diabetes. Skeletal muscle wasting, which currently has no approved therapy, is a debilitating condition resulting from either reduced muscle protein synthesis or increased degradation. The imbalance in protein synthesis could occur from increased expression and function of muscle-specific ubiquitin ligases, muscle atrophy F-box (MAFbx)/atrogin-1 and muscle ring finger 1 (MuRF1), or decreased function of the IGF-I and phosphatidylinositol-3 kinase/Akt kinase pathways. We examined the effects of a nonsteroidal tissue selective androgen receptor modulator (SARM) and testosterone on glucocorticoid-induced muscle atrophy and castration-induced muscle atrophy. The SARM and testosterone propionate blocked the dexamethasone-induced dephosphorylation of Akt and other proteins involved in protein s...

ownload H-indol-2-yl)phenyl)(3,4,5-trimethoxyphenyl)methanone (I-387) is a novel synthetic compou... more ownload H-indol-2-yl)phenyl)(3,4,5-trimethoxyphenyl)methanone (I-387) is a novel synthetic compound that ts tubulin action and exhibits potent antitumor activity in various preclinical models. I-387 inhibited vitro growth of several human cancer cell lines with IC50 values in the range of 15 to 39 nmol/L. olar concentrations of the compound induced apoptosis and caused phosphorylation of the antiatic protein Bcl-2. I-387 induced a strong and concentration-dependent G2-M arrest in PC-3 cells by tutive activation of Cdc2/cyclin B1 complex and destabilized polymerization of purified tubulin o by binding to the colchicine-binding site. In vivo, I-387 treatment effectively inhibited tumor growth e bearing PC-3 tumor xenografts. In vitro studies of nerve growth factor–dependent neurite outh in PC12 pheochromocytoma cells and in vivo studies of mouse behavior showed that I-387 was urotoxic than vinblastine and vincristine, tubulin destabilizers with known neurotoxicity. Interestingltidrug-...

jpet.aspetjournals.org D ow nloaded from JPET #88344

Experimental and Molecular Therapeutics

Molecular Pharmacology

Interfering with microtubule dynamics is a well-established strategy in cancer treatment; however... more Interfering with microtubule dynamics is a well-established strategy in cancer treatment; however, many microtubule-targeting agents are associated with drug resistance and adverse effects. Substantial evidence points to ATP-binding cassette (ABC) transporters as critical players in the development of resistance. Herein, we demonstrate the efficacy of DJ95 (2-(1H-indol-6-yl)-4-(3,4,5trimethoxyphenyl)-1H-imidazo[4,5-c]pyridine), a novel tubulin inhibitor, in a variety of cancer cell lines, including malignant melanomas, drug-selected resistant cell lines, specific ABC transporter-overexpressing cell lines, and the National Cancer Institute 60 cell line panel. DJ95 treatment inhibited cancer cell migration, caused morphologic changes to the microtubule network foundation, and severely disrupted mitotic spindle formation of mitotic cells. The high-resolution crystal structure of DJ95 in complex with tubulin protein and the detailed molecular interactions confirmed its direct binding to the colchicine site. In vitro pharmacological screening of DJ95 using SafetyScreen44 (Eurofins Cerep-Panlabs) revealed no significant off-target interactions, and pharmacokinetic analysis showed that DJ95 was maintained at therapeutically relevant plasma concentrations for up to 24 hours in mice. In an A375 xenograft model in nude mice, DJ95 inhibited tumor growth and disrupted tumor vasculature in xenograft tumors. These results demonstrate that DJ95 is potent against a variety of cell lines, demonstrated greater potency to ABC transporter-overexpressing cell lines than existing tubulin inhibitors, directly targets the colchicine binding domain, exhibits significant antitumor efficacy, and demonstrates vascular-disrupting properties. Collectively, these data suggest that DJ95 has great potential as a cancer therapeutic, particularly for multidrug resistance phenotypes, and warrants further development. SIGNIFICANCE STATEMENT Paclitaxel is a widely used tubulin inhibitor for cancer therapy, but its clinical efficacy is often limited by the development of multidrug resistance. In this study, we reported the preclinical characterization of a new tubulin inhibitor DJ95, and demonstrated its abilities to overcome paclitaxel resistance, disrupt tumor vasculature, and exhibit significant antitumor efficacy.

Medicinal Research Reviews

Microtubule (MT)‐targeting agents are highly successful drugs as chemotherapeutic agents, and thi... more Microtubule (MT)‐targeting agents are highly successful drugs as chemotherapeutic agents, and this is attributed to their ability to target MT dynamics and interfere with critical cellular functions, including, mitosis, cell signaling, intracellular trafficking, and angiogenesis. Because MT dynamics vary in the different stages of the cell cycle, these drugs tend to be the most effective against mitotic cells. While this class of drug has proven to be effective against many cancer types, significant hurdles still exist and include overcoming aspects such as dose limited toxicities and the development of resistance. Newer generations of developed drugs attack these problems and alternative approaches such as the development of dual tubulin and kinase inhibitors are being investigated. This approach offers the potential to show increased efficacy and lower toxicities. This review covers different categories of MT‐targeting agents, recent advances in dual inhibitors, and current challenges for this drug target.

Molecules (Basel, Switzerland), Jan 2, 2016

Extensive research over the last decade has resulted in a number of highly potent tubulin polymer... more Extensive research over the last decade has resulted in a number of highly potent tubulin polymerization inhibitors acting either as microtubule stabilizing agents (MSAs) or microtubule destabilizing agents (MDAs). These inhibitors have potent cytotoxicity against a broad spectrum of human tumor cell lines. In addition to cytotoxicity, a number of these tubulin inhibitors have exhibited abilities to inhibit formation of new blood vessels as well as disrupt existing blood vessels. Tubulin inhibitors as a vascular disrupting agents (VDAs), mainly from the MDA family, induce rapid tumor vessel occlusion and massive tumor necrosis. Thus, tubulin inhibitors have become increasingly popular in the field of tumor vasculature. However, their pharmaceutical application is halted by a number of limitations including poor solubility and toxicity. Thus, recently, there has been considerable interests in the nanoparticle drug delivery of tubulin inhibitors to circumvent those limitations. This a...

Cancer Chemotherapy and Pharmacology, 2011

The dimeric pyrrolobenzodiazepine SJG-136 (NSC 694501, SG2000) has potent in vitro antiproliferat... more The dimeric pyrrolobenzodiazepine SJG-136 (NSC 694501, SG2000) has potent in vitro antiproliferative activity and in vivo antitumor activity associated with binding in the minor groove of DNA and formation of covalent interstrand DNA cross-links. The pharmacokinetics and in vitro metabolism of SJG-136 and as well as the feasibility of using the Comet assay to measure in vivo interstrand DNA cross-links, was assessed in the rat. SJG-136 pharmacokinetics and pharmacodynamics were characterized in rats following single-dose administration of 15 and 50 μg/kg or multiple-dose administration of 25 μg/kg/day for 5 days. DNA damage was measured in peripheral blood mononuclear cells using the Comet assay. SJG-136 oxidative metabolism was characterized in rat liver microsomes. SJG-136 half-life, clearance and volume of distribution values were 9 min, 190 ml/min/m(2), and 1780 ml/m(2), respectively. SJG-136 did not accumulate in plasma during treatment with 25 μg/kg/day for 5 days. Treatment with SJG-136 produced the anticipated DNA interstrand cross-links, as well as DNA strand breaks, in rat PBMCs. Oxidative metabolism of SJG-136 in rat liver microsomes was catalyzed by CYP3A isoforms and produced a previously unreported monomeric metabolite. Plasma concentrations of SJG-136 associated with pharmacological activity and in vitro antiproliferative activity were achieved with doses that were tolerated by rats. CYP3A isoforms are the predominant P450s catalyzing SJG-136 metabolism. The comet assay detects DNA damage in PBMCs from rats treated with SJG-136 and is being used in clinical trials to monitor in vivo lesions produced by SJG-136.

Clinical Cancer Research

Androgen receptor (AR)-targeting prostate cancer drugs, which are predominantly competitive ligan... more Androgen receptor (AR)-targeting prostate cancer drugs, which are predominantly competitive ligand binding domain (LBD)-binding antagonists, are inactivated by common resistance-mechanisms. It is important to develop next-generation mechanistically-distinct drugs to treat castration-and drug-resistant prostate cancers. Here, we describe a second-generation AR pan-antagonist (UT-34) that degrades the AR and AR splice variants. UT-34 inhibits the wild-type and LBD mutant ARs comparably and inhibits the in vitro proliferation and in vivo growth of enzalutamide-sensitive and resistant prostate cancer xenografts. In preclinical models, UT-34 induced the regression of enzalutamide-resistant tumors at doses when the AR is degraded; but, at lower doses when the AR is just antagonized, it inhibits, without shrinking, the tumors. This indicates that degradation might be a prerequisite for tumor regression. Mechanistically, UT-34 promotes a conformation that is distinct from the LBD-binding competitive antagonist, enzalutamide, and degrades the AR through the ubiquitin proteasome mechanism. UT-34 has a broad safety margin and exhibits no cross-reactivity with G-Protein Coupled Receptor, kinase, and nuclear receptor family members. Collectively, UT-34 exhibits the properties necessary for a next-generation prostate cancer drug.

International Journal of Molecular Sciences

Traditional endocrine therapy for prostate cancer (PCa) has been directed at suppression of the a... more Traditional endocrine therapy for prostate cancer (PCa) has been directed at suppression of the androgen receptor (AR) signaling axis since Huggins et al. discovered that diethylstilbestrol (DES; an estrogen) produced chemical castration and PCa tumor regression. Androgen deprivation therapy (ADT) still remains the first-line PCa therapy. Insufficiency of ADT over time leads to castration-resistant PCa (CRPC) in which the AR axis is still active, despite castrate levels of circulating androgens. Despite the approval and use of multiple generations of competitive AR antagonists (antiandrogens), antiandrogen resistance emerges rapidly in CRPC due to several mechanisms, mostly converging in the AR axis. Recent evidence from multiple groups have defined noncompetitive or noncanonical direct binding sites on AR that can be targeted to inhibit the AR axis. This review discusses new developments in the PCa treatment paradigm that includes the next-generation molecules to noncanonical sites...