Soon-Sun Hong

Melatonin ameliorates cerulein‐induced pancreatitis by the modulation of nuclear erythroid 2‐related factor 2 and nuclear factor‐kappaB in rats

Abstract:  Melatonin exhibits a wide variety of biological effects, including antioxidant and anti‐inflammatory functions. Its antioxidant role impedes the etiopathogenesis of pancreatitis, but little is known about the signaling pathway of melatonin in the induction of antioxidant enzymes in acute pancreatitis (AP). The aim of this study was to determine whether melatonin could prevent cerulein‐induced AP through nuclear factor erythroid 2‐related factor 2 (Nrf2) and curtail inflammation by inhibition of NF‐κB. AP was induced by two intraperitoneal (i.p.) injections of cerulein at 2 h intervals (50 μg/kg) in Sprague‐Dawley rats. Melatonin (10 or 50 mg/kg/daily, i.p.) was administered 24 h before each injection of cerulein. The rats were killed 12 h after the last injection. Acinar cell degeneration, pancreatic edema, and inflammatory infiltration were significantly different in cerulein‐ and melatonin‐treated rats. Melatonin significantly reduced amylase, lipase, MPO, and MDA levels, and increased antioxidant enzyme activities including SOD and GPx, which were decreased in AP (P < 0.05). Melatonin increased the expression of NQO1, HO‐1, and SOD2 when compared with the cerulein‐induced AP group (P < 0.05). In addition, melatonin increased Nrf2 expression, and reduced expressions of tumor necrosis factor‐alpha, IL‐1β, IL‐6, IL‐8, and iNOS. The elevated nuclear binding of NF‐κB in the cerulein‐induced pancreatitis group was inhibited by melatonin. These results show that melatonin increases antioxidant enzymes and Nrf2 expression, and limits inflammatory mediators in cerulein‐induced AP. It is proposed that melatonin may play an important role in oxidative stress via the Nrf2 pathway in parallel with reduction of inflammation by NF‐κB inhibition.

Proteomic Analysis of the Anti-Cancer Effect of 20S-Ginsenoside Rg3 in Human Colon Cancer Cell Lines

Ginseng is a well known herbal medicine in Asia, and ginsenoside Rg3 has anti-cancer and various pharmacological effects. In particular, 20S-ginsenoside Rg3 may increase the anti-proliferative effects of chemotherapy. The authors investigated the mechanism of the anti-proliferative effect of 20S-Rg3 at the protein level in HT29 colon cancer cells. MTT, caspase-3 assays, and flow cytometry analysis were performed to determine cytotoxicity and apoptosis, and proteomic analysis was performed by two-dimensional gel electrophoresis and MALDI-TOF/TOF MS, and a database was used to identify protein changes in 20S-Rg3 treated HT29 cells. The proteins identified included down-regulated Rho GDP dissociation inhibitor, up-regulated tropomyosin1, and annexin5 and glutathione s-transferase p1, which are apoptosis associated proteins. The anti-proliferative mechanism of 20S-Rg3 was found to be involved in mitotic inhibition, DNA replication, and repair and growth factor signaling. The findings of this study suggest that the cytotoxicity of 20S-Rg3 in colon cancer is dependent on several mechanisms, including apoptosis.

Melatonin downregulates nuclear erythroid 2-related factor 2 and nuclear factor-kappaB during prevention of oxidative liver injury in a dimethylnitrosamine model

Abstract:  Melatonin has potent hepatoprotective effects as an antioxidant. However, the signaling pathway of melatonin in the induction of antioxidant enzymes against acute liver injury is not fully understood. The study aimed to determine whether melatonin could prevent dimethylnitrosamine (DMN)‐induced liver injury through nuclear erythroid 2‐related factor 2 (Nrf2) and inflammation. Liver injury was induced in rats by a single injection of DMN (30 mg/kg, i.p.). Melatonin treatment (50 mg/kg/daily, i.p.) was initiated 24 hr after DMN injection for 14 days, after which the rats were killed and samples were collected. Serum and antioxidant enzyme activities improved in melatonin‐treated rats, compared with DMN‐induced liver injury group (P < 0.01). Melatonin reduced the infiltration of inflammatory cells and necrosis in the liver, and increased the expression of NADPH: quinone oxidoreductase‐1, heme oxygenase‐1, and superoxide dismutase‐2, which were decreased by DMN. Melatonin increased expression of novel transcription factor, Nrf2, and decreased expression of inflammatory mediators including tumor necrosis factor‐alpha, interleukin (IL)‐1β, IL‐6, and inducible nitric oxide synthase. The increased nuclear binding of nuclear factor‐kappa B (NF‐κB) in the DMN‐induced liver injury group was inhibited by melatonin. Our results show that melatonin increases antioxidant enzymes and Nrf2 expression in parallel with the decrease of inflammatory mediators in DMN‐induced liver injury, suggesting that melatonin may play a role of antioxidant defense via the Nrf2 pathway, by reducing inflammation by NF‐κB inhibition.

Design, synthesis, and evaluation of 3,5-disubstituted 7-azaindoles as Trk inhibitors with anticancer and antiangiogenic activities.

Tropomyosin-related kinase A (TrkA) is considered a promising target in the development of a therapeutic treatment of cancer and pain. In this study, we designed and synthesized a series of novel 7-azaindole-based Trk kinase inhibitors through the structure-based design strategy. By varying the functional groups at the 3 and 5 positions of a 7-azaindole scaffold, we studied the structure-activity relationships (SAR) profiles and identified a series of potent Trk inhibitors. Representative derivatives showed desirable activity in cellular proliferation and apoptosis assays. Moreover, these inhibitors exhibited noteworthy antiangiogenic activity.

Progress in cancer therapy targeting c-Met signaling pathway

AbstactA primary hurdle in developing anticancer therapeutics is to selectively target cancer cells while sparing normal tissues. Oncogenic protein kinases represent a class of biologically important targets for cancer intervention. Among them, c-Met is a receptor tyrosine kinase (RTK) that has low activity in normal tissues but is dysregulated in many tumor types. The c-Met is the prototype member of a subfamily of RTKs, which includes Ron, which is structurally distinct from other RTK families. It is the only known high-affinity receptor for hepatocyte growth factor, also known as scatter factor. HGF and c-Met are both required for normal mammalian development. In adults, both are widely expressed in a variety of tissues; however, their expression is normally very low and is involved mainly in tissue damage, repair and regeneration. The results of in vitro and in vivo experiments have shown that this receptor-growth factor pair is involved in multiple physiologic cellular responses, including cell proliferation, survival, differentiation, motility, and invasion. Here, as well as presenting the biological aspects of c-Met signaling regulation, we consider recent findings that have provided new knowledge at the molecular, cellular, and animal study. Also, we describe how the c-Met pathway is tuned by the functional cooperation between various signal transducers. We then discuss the progress in the development of agents that target the c-Met pathway, with an emphasis on small molecules of c-Met kinase inhibitors. Finally, we provide our perspective in terms of possible future trends and limitation in this field.

Porous silicon nanoparticles for cancer photothermotherapy

The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

HIF-1alpha: a valid therapeutic target for tumor therapy.

Hypoxia plays a major role in the induction of angiogenesis during tumor development. One mechanism by which tumor cells respond to a reduced oxygen level is via the activation of hypoxia-inducible factor-1 (HIF-1). HIF-1 is an oxygen-dependent transcriptional activator that plays crucial roles in the angiogenesis of tumors and mammalian development. HIF-1 consists of a constitutively expressed HIF-1beta subunit and the highly regulated HIF-1alpha subunits. The stability and activity of HIF-1alpha are regulated by various post-translational modifications, hydroxylation, acetylation, phosphorylation and sumoyaltion. Therefore, HIF-1alpha interacts with several protein factors including PHD, pVHL, ARD-1, SUMO and p300/CBP. Under normoxia, the HIF-1alpha subunit is rapidly degraded via the von Hippel-Lindau tumor suppressor gene product (pVHL)-mediated ubiquitin/proteasome pathway. The association of pVHL and HIF-1alpha under normoxic conditions is triggered by the hydroxylation of prolines and the acetylation of lysine within a polypeptide segment known as the oxygen-dependent degradation (ODD) domain. On the contrary, under the hypoxia condition, the HIF-1alpha subunit becomes stable and interacts with coactivators such as p300/CBP to modulate its transcriptional activity. Under hypoxic conditions, HIF-1 eventually acts as a master regulator of numerous hypoxia-inducible genes. The target genes of HIF-1 are especially related to angiogenesis, cell proliferation and survival, and to glucose and iron metabolism. Moreover, it was reported that the activation of HIF-1alpha is closely associated with a variety of tumors and oncogenic pathways. Hence, the blocking of HIF-1alpha itself or the blocking of HIF-1alpha interacting proteins inhibits tumor growth. Based on these findings, HIF-1 can be a prime target for anticancer therapies. Therefore, this review summarizes the molecular mechanism of HIF-1alpha stability, the biological functions of HIF-1 and its potential applications for cancer therapies.

Sensitization of TRAIL-Induced Cell Death by 20(S)-Ginsenoside Rg3 via CHOP-Mediated DR5 Upregulation in Human Hepatocellular Carcinoma Cells

The TRAIL pathway is a potential therapeutic target for anticancer drugs due to selective cytotoxicity in cancer cells. Despite considerable promise, TRAIL or TRAIL receptor agonists have been used thus far with limited success in multiple clinical trials, in part due to acquired TRAIL resistance during chemotherapeutic treatment. Hepatocellular carcinoma (HCC) is a common solid tumor and the third leading cause of cancer-related death worldwide. Classical chemotherapy is not effective for HCC treatment and targeted therapy is limited to sorafenib. Isolated from Panax ginseng CA Meyer, 20(S)-ginsenoside Rg3 is a steroidal saponin with high pharmacologic activity that has been shown to sensitize cells to some chemotherapeutic agents. We investigated the sensitizing effect of Rg3 on TRAIL-induced cell death in HCC cells. We show Rg3 is capable of promoting TRAIL-induced apoptosis in a number of HCC cell lines, including HepG2, SK-Hep1, Huh-7, and Hep3B, but not in normal HL-7702 hepatocytes, indicating that Rg3 sensitization to TRAIL may be specific to cancer cells. Mechanistically, we found that Rg3 upregulates DR5 expression at the transcriptional level. DR5 upregulation in this case is mediated by C/EBP homology protein (CHOP), an important endoplasmic reticulum stress responsive protein. Furthermore, Rg3 is well tolerated and enhances the therapeutic efficacy of TRAIL in mouse xenograft models, suggesting that chemosensitization also occurs in vivo. Taken together, our study identifies Rg3 as a novel anticancer therapeutic agent and supports the further development of Rg3 as a chemosensitizer in combined therapy with TRAIL. Mol Cancer Ther; 12(3); 274–85. ©2012 AACR.

Poloxamer/Cyclodextrin/Chitosan-Based Thermoreversible Gel for Intranasal Delivery of Fexofenadine Hydrochloride

To enhance permeation and solubility of an intranasal delivery system of fexofenadine hydrochloride (FXD HCl), a new formulation using poloxamer 407 (P407)/hydroxypropyl-β-cyclodextrin (HP-β-CD)-based thermoreversible gels with chitosan, was developed. Prepared gels were characterized by gelation temperature, viscosity, viscoelasticity, and drug release profile. The in vitro permeation study was performed in primary human nasal epithelial cell monolayers cultured by air-liquid interface method. The addition of chitosan caused the slight elevation of gelation temperature and viscosity-enhancing effect. Viscosity enhancement by the incorporation of chitosan caused the retardation of drug release from P407 gels in in vitro release test. The in vitro permeation profile showed that the increase in chitosan content (0.1% and 0.3%, w/v) significantly enhanced the permeation of FXD HCl. After intranasal administration of P407/HP-β-CD-based thermoreversible gels containing 0.1% and 0.3% of chitosan in rabbits at 0.5 mg/kg dose, plasma concentrations of FXD HCl were significantly higher than those of nasal solutions (p < 0.05). In particular, the bioavailability of the optimized thermoreversible gel containing 0.3% chitosan was about 18-fold higher than that of the solution type. These results suggested the feasibility that thermosensitive gels could be used as an effective dosage form to enhance the nasal absorption of FXD HCl.

The use of low molecular weight heparin-pluronic nanogels to impede liver fibrosis by inhibition the TGF-β/Smad signaling pathway.

Low molecular weight heparin (LH) has been reported to have anti-fibrotic and anti-cancer effects. To enhance the efficacy and minimize adverse effects of LH, a low molecular weight heparin-pluronic nanogel (LHP) was synthesized by conjugating carboxylated pluronic F127 to LH. The LHP reduced anti-coagulant activity by about 33% of the innate activity. Liver fibrosis was induced by the injection of 1% dimethylnitrosamine (DMN) in rats, and LH or LHP (1000 IU/kg body weight) was treated once daily for 4 weeks. LHP administration prevented DMN-mediated liver weight loss and decreased the values of aspartate transaminase, alanine transaminase, total bilirubin, and direct bilirubin. LHP markedly reduced the fibrotic area compared to LH. Also, LHP potently inhibited mRNA or protein expression of alpha-smooth muscle actin, collagen type I, matrix metalloproteinase-2, and tissue inhibitor of metalloproteinase-1 compared to LH, in DMN-induced liver fibrosis. In addition, LHP decreased the expression of transforming growth factor-β(1) (TGF-β(1)), p-Smad 2, and p-Smad 3, which are all important molecules of the TGF-β/Smad signaling pathway. The results support an LHP shows anti-fibrotic effect in the liver via inhibition of the TGF-β/Smad pathway as well as by the elimination of the extracellular matrix.