Gahee Bahn

Cancer Therapy Using Ultrahigh Hydrophobic Drug-Loaded Graphene Derivatives

This study aimed to demonstrate that curcumin (Cur)-containing graphene composites have high anticancer activity. Specifically, graphene-derivatives were used as nanovectors for the delivery of the hydrophobic anticancer drug Cur based on pH dependence. Different Cur-graphene composites were prepared based on polar interactions between Cur and the number of oxygen-containing functional groups of respective starting materials. The degree of drug-loading was found to be increased by increasing the number of oxygen-containing functional groups in graphene-derivatives. We demonstrated a synergistic effect of Cur-graphene composites on cancer cell death (HCT 116) both in vitro and in vivo. As-prepared graphene quantum dot (GQD)-Cur composites contained the highest amount of Cur nano-particles and exhibited the best anticancer activity compared to the other composites including Cur alone at the same dose. This is the first example of synergistic chemotherapy using GQD-Cur composites simultaneous with superficial bioprobes for tumor imaging.

Pin1 promotes neuronal death in stroke by stabilizing Notch intracellular domain

Stroke is a leading cause of mortality and disability. The peptidyl‐prolyl cis/trans isomerase Pin1 regulates factors involved in cell growth. Recent evidence has shown that Pin1 plays a major role in apoptosis. However, the role of Pin1 in ischemic stroke remains to be investigated.

Inhibition of Drp1 Ameliorates Synaptic Depression, Aβ Deposition, and Cognitive Impairment in an Alzheimer's Disease Model

Excessive mitochondrial fission is a prominent early event and contributes to mitochondrial dysfunction, synaptic failure, and neuronal cell death in the progression of Alzheimers disease (AD). However, it remains to be determined whether inhibition of excessive mitochondrial fission is beneficial in mammal models of AD. To determine whether dynamin-related protein 1 (Drp1), a key regulator of mitochondrial fragmentation, can be a disease-modifying therapeutic target for AD, we examined the effects of Drp1 inhibitor on mitochondrial and synaptic dysfunctions induced by oligomeric amyloid-β (Aβ) in neurons and neuropathology and cognitive functions in Aβ precursor protein/presenilin 1 double-transgenic AD mice. Inhibition of Drp1 alleviates mitochondrial fragmentation, loss of mitochondrial membrane potential, reactive oxygen species production, ATP reduction, and synaptic depression in Aβ-treated neurons. Furthermore, Drp1 inhibition significantly improves learning and memory and prevents mitochondrial fragmentation, lipid peroxidation, BACE1 expression, and Aβ deposition in the brain in the AD model. These results provide evidence that Drp1 plays an important role in Aβ-mediated and AD-related neuropathology and in cognitive decline in an AD animal model. Therefore, inhibiting excessive Drp1-mediated mitochondrial fission may be an efficient therapeutic avenue for AD. SIGNIFICANCE STATEMENT Mitochondrial fission relies on the evolutionary conserved dynamin-related protein 1 (Drp1). Drp1 activity and mitochondria fragmentation are significantly elevated in the brains of sporadic Alzheimers disease (AD) cases. In the present study, we first demonstrated that the inhibition of Drp1 restored amyloid-β (Aβ)-mediated mitochondrial dysfunctions and synaptic depression in neurons and significantly reduced lipid peroxidation, BACE1 expression, and Aβ deposition in the brain of AD mice. As a result, memory deficits in AD mice were rescued by Drp1 inhibition. These results suggest that neuropathology and combined cognitive decline can be attributed to hyperactivation of Drp1 in the pathogenesis of AD. Therefore, inhibitors of excessive mitochondrial fission, such as Drp1 inhibitors, may be a new strategy for AD.

Notch1 targeting siRNA delivery nanoparticles for rheumatoid arthritis therapy.

Notch pathway plays a pivotal role in synoviocytes involved in progression of rheumatoid arthritis (RA). Herein, we designed the Notch1 targeting siRNA delivery nanoparticles (siRNA-NPs) in order to confirm the anti-inflammatory effect in collagen-induced arthritis (CIA) model. The siRNA-NPs were successfully produced by encapsulating polymerized siRNA (poly-siRNA) into thiolated glycol chitosan (tGC) nanoparticles in aqueous condition. The in vitro Notch1 inhibition of siRNA-NPs in murine macrophage cell (RAW 264.7) was confirmed using confocal microscopy and real time PCR. Fluorescently labeled siRNA-NPs were successfully transfected in RAW 264.7 and modulated the expression of Notch1 in mRNA level. For in vivo study, siRNA-NPs exhibited the higher targeting efficiency in the arthritic joins of CIA mice, confirmed by the near-infrared fluorescence (NIRF) imaging. Furthermore, inhibition of Notch1 with siRNA-NPs resulted in retarded progression of inflammation, bone erosion, and cartilage damage in CIA mice. Novel Notch1 targeting siRNA delivery system of siRNA-NPs showed effective RA treatment by suppressing Notch1 signaling pathway without undesirable severe toxicity. Thus, Notch1 inhibiting siRNA-NPs demonstrated the great potential in RA therapeutics that was hard to be achieved using conventional drugs.

Notch1 deficiency decreases hepatic lipid accumulation by induction of fatty acid oxidation

Notch signaling pathways modulate various cellular processes, including cell proliferation, differentiation, adhesion, and communication. Recent studies have demonstrated that Notch1 signaling also regulates hepatic glucose production and lipid synthesis. However, the effect of Notch1 signaling on hepatic lipid oxidation has not yet been directly investigated. To define the function of Notch1 signaling in hepatic lipid metabolism, wild type mice and Notch1 deficient antisense transgenic (NAS) mice were fed a high-fat diet. High-fat diet -fed NAS mice exhibited a marked reduction in hepatic triacylglycerol accumulation compared with wild type obese mice. The improved fatty liver was associated with an increased expression of hepatic genes involved in fatty acid oxidation. However, lipogenic genes were not differentially expressed in the NAS liver, suggesting lipolytic-specific regulatory effects by Notch1 signaling. Expression of fatty acid oxidative genes and the rate of fatty acid oxidation were also increased by inhibition of Notch1 signaling in HepG2 cells. In addition, similar regulatory effects on lipid accumulation were observed in adipocytes. Taken together, these data show that inhibition of Notch1 signaling can regulate the expression of fatty acid oxidation genes and may provide therapeutic strategies in obesity-induced hepatic steatosis.

THE DRUG TG REDUCING BACE1 EXPRESSION LEVEL AND PREVENTING COGNITIVE IMPAIRMENT IN ALZHEIMER'S DISEASE MICE

used for chronic efficacy studies. Results: CNP520 is selective for BACE-1 over BACE-2 and highly selective over pepsin, cathepsin D & E, and renin. Low nanomolar inhibition of Ab and sAPPb release was observed in cell assays using wt-APP cells. The free fraction of CNP520 in the rat brain, and the concentration of CNP520 in the CSF, was comparable to unbound blood concentrations, indicating excellent brain penetration. Oral dosing of CNP520 reduced Ab in the rat brain by more than 80%. A single CNP520 dose in dogs reduced CSF Ab for 72 hours, in agreement with long terminal half-lives (9.5-23 hours) in animals. CNP520 did not induce any hair depigmentation when dosed to mice for 8 weeks at a dose for > 90% Ab reduction. No hypopigmentation was observed in chronic studies in transgenic mice, and during long-term toxicology studies. CNP520 was dosed into APP23 mice 6 months and showed dose-dependent reduction of Triton TX-100 soluble and insoluble Ab. At the high dose, the levels of deposited Ab40/42 were indistinguishable from baseline. Conclusions: Preclinical data predict that more than 80% Ab reduction can be reached in humans at steady state. CNP520 stopped further amyloid-b deposition in APP transgenic mice, indicating that the compound may be able to show long term efficacy against Ab deposition in humans.

Inhibition of Notch1 induces population and suppressive activity of regulatory T cell in inflammatory arthritis

Inhibition of Notch signalling has shown anti-inflammatory properties in vivo and in vitro models of rheumatoid arthritis (RA). The objective of this study was to determine whether Notch1 might play a role in regulating T-regulatory cells (Tregs) in animal models of RA. Methods: Collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) were induced in C57BL/6, Notch1 antisense transgenic (NAS) or DBA1/J mice. We examined whether pharmacological inhibitors of γ-secretase (an enzyme required for Notch1 activation) and antisense-mediated knockdown of Notch1 could attenuate the severity of inflammatory arthritis in CIA and CAIA mice. Proportions of CD4+CD25+Foxp3+ Treg cells were measured by flow cytometry. To assess the suppressive capacity of Treg toward responder cells, CFSE-based suppression assay of Treg was performed. Results: γ-secretase inhibitors and antisense-mediated knockdown of Notch1 reduced the severity of inflammatory arthritis in both CIA and CAIA mice. Pharmacological and genetic inhibition of Notch1 signalling induced significant elevation of Treg cell population in CIA and CAIA mice. We also demonstrated that inhibition of Notch signalling suppressed the progression of inflammatory arthritis through modulating the expansion and suppressive function of regulatory T (Treg) cells. Conclusion: Pharmacological and genetic inhibition of Notch1 signalling suppresses the progression of inflammatory arthritis through modulating the population and suppressive function of Treg cells in animal models of RA.

Sulfuretin Prevents Obesity and Metabolic Diseases in Diet Induced Obese Mice

The global obesity epidemic and associated metabolic diseases require alternative biological targets for new therapeutic strategies. In this study, we show that a phytochemical sulfuretin suppressed adipocyte differentiation of preadipocytes and administration of sulfuretin to high fat diet-fed obese mice prevented obesity and increased insulin sensitivity. These effects were associated with a suppressed expression of inflammatory markers, induced expression of adiponectin, and increased levels of phosphorylated ERK and AKT. To elucidate the molecular mechanism of sulfuretin in adipocytes, we performed microarray analysis and identified activating transcription factor 3 (Atf3) as a sulfuretin-responsive gene. Sulfuretin elevated Atf3 mRNA and protein levels in white adipose tissue and adipocytes. Consistently, deficiency of Atf3 promoted lipid accumulation and the expression of adipocyte markers. Sulfuretin’s but not resveratrol’s anti-adipogenic effects were diminished in Atf3 deficient cells, indicating that Atf3 is an essential factor in the effects of sulfuretin. These results highlight the usefulness of sulfuretin as a new anti-obesity intervention for the prevention of obesity and its associated metabolic diseases.

Atf3 induction is a therapeutic target for obesity and metabolic diseases

Activating transcription factor 3 (Atf3) has been previously demonstrated to impact obesity and metabolism. However, a metabolic role of Atf3 in mice remains debatable. We investigated the role of Atf3 in mice and further investigated Atf3 expression as a therapeutic target for obesity and metabolic diseases. Atf3 knockout (KO) mice fed with a high fat diet (HFD) aggravated weight gain and impaired glucose metabolism compared to littermate control wild type (WT) mice. Atf3 KO aged mice fed with a chow diet (CD) for longer than 10 months also displayed increased body weight and fat mass compared to WT aged mice. We also assessed requirements of Atf3 in a phytochemical mediated anti-obese effect. Effect of sulfuretin, a previously known phytochemical Atf3 inducer, in counteracting weight gain and improving glucose tolerance was almost completely abolished in the absence of Atf3, indicating that Atf3 induction can be a molecular target for preventing obesity and metabolic diseases. We further identified other Atf3 small molecule inducers that exhibit inhibitory effects on lipid accumulation in adipocytes. These data highlight the role of Atf3 in obesity and further suggest the use of chemical Atf3 inducers for prevention of obesity and metabolic diseases.

DRUG REPOSITIONING OF XHC FOR ALZHEIMER’S DISEASE: BACE1 PROMOTER REPRESSING ACTIVITY OF XHC

Background:Amyloid hypothesis postulated that exceed extracellular amyloid beta deposits are the fundamental cause of Alzheimer’s disease. Amyloid beta is produced by sequential proteolysis to amyloid beta precursor protein (APP) by beta-secretase (BACE1) and gamma-secretase. Another important phenomenon in AD patient is increased BACE1 expression. Methods:Our strategy is to find specific drugs reducing BACE1 expression rather than direct inhibition of BACE1. Using USA FDA approved drug library (Prestwick Chemical Library), we could discover putative therapeutic chemicals by cell based assay. Results:Among those candidates, XHC reduced the levels of BACE1 protein and mRNA in SH-SY5Y cells. A soluble APPb and C99 which are the products of BACE1 protease, were also decreased by treatment of XHC. We also confirmed that XHC could improve cognitive functions of 3XTg-AD mice. Decreased level of amyloid beta deposition and BACE1 expression also observed in XHC-treated AD mice. Conclusions: The fact that XHC is orally efficacious in AD animal models and is clinically safe to use make XHC an excellent candidate for advancement to clinical AD trials.