Mi-Young Ahn

Anticancer activity of CopA3 dimer peptide in human gastric cancer cells.

CopA3 is a homodimeric α-helical peptide derived from coprisin which is a defensin-like antimicrobial peptide that was identified from the dung beetle, Copris tripartitus. CopA3 has been reported to have anticancer activity against leukemia cancer cells. In the present study, we investigated the anticancer activity of CopA3 in human gastric cancer cells. CopA3 reduced cell viability and it was cytotoxic to gastric cancer cells in the MTS and LDH release assay, respectively. CopA3 was shown to induce necrotic cell death of the gastric cancer cells by flow cytometric analysis and acridine orange/ethidium bromide staining. CopA3-induced cell death was mediated by specific interactions with phosphatidylserine, a membrane component of cancer cells. Taken together, these data indicated that CopA3 mainly caused necrosis of gastric cancer cells, probably through interactions with phosphatidylserine, which suggests the potential utility of CopA3 as a cancer therapeutic. [BMB Reports 2015; 48(6): 324-329]

Expressed sequence tag analysis of the diapausing queen of the bumblebee Bombus ignitus

We constructed a full‐length cDNA library from diapausing queens of the bumblebee Bombus ignitus. A total of 480 randomly selected clones was sequenced by single‐run 5′‐end sequencing. Of these, there were 437 high quality clones, 23 poor quality clones and 20 read‐fail clones. Each high quality clone sequence was searched against a public protein database. The most frequently found matching genes were ribosomal proteins (12.5%), p10 (3.58%), cytochrome P450 monooxygenase (3.13%) and sensory appendage protein (2.9%). Sequence similarity analysis between bumblebees and other insect species showed that 72 out of 437 (16.5%) bumblebee expressed sequence tags (EST) matched sequences of Apis mellifera, with matches to Drosophila melanogaster (6.6%), Caenorhabditis briggsae (6.2%), Lysiphlebus testaceipes (4.8%), Periplaneta americana (3.7%) and Anopheles gambiae (3.4%) following, suggesting that sequence similarity of bumblebee EST is closest to that of A. mellifera. Functional classification of EST based on Gene Ontology showed that most genes found by sequencing are associated with physiological processes in the bumblebee. The results of sequencing and analysis of our 437 cDNA demonstrated that high‐throughput EST sequencing and data analysis are powerful means for identifying novel genes and for expression profiling. Our bumblebee EST collection could be a useful platform for further studies of gene expression in diapausing bumblebees.

Anticancer activity of a synthetic peptide derived from harmoniasin, an antibacterial peptide from the ladybug Harmonia axyridis.

Harmoniasin is a defensin-like antimicrobial peptide identified from the ladybug Harmonia axyridis. Among the synthetic homodimer peptide analogues derived from harmoniasin, HaA4 has been found to have antibacterial activity without hemolytic activity. In this study, we investigated whether HaA4 has anticancer activity against human leukemia cell lines such as U937 and Jurkat cells. HaA4 manifested cytotoxicity and decreased the cell viability of U937 and Jurkat cells in MTS assay and LDH release assay. We found that HaA4 induced apoptotic and necrotic cell death of the leukemia cells using flow cytometric analysis, acridine orange/ethidium bromide staining and nucleosomal fragmentation of genomic DNA. Activation of caspase-7 and -9 and fragmentation of poly (ADP-ribose) polymerase was detected in the HaA4-treated leukemia cells, suggesting induction of a caspase-dependent apoptosis pathway by HaA4. Caspase-dependent apoptosis was further confirmed by reversal of the HaA4-induced viability reduction by treatment of Z-VAD-FMK, a pan-caspase inhibitor. In conclusion, HaA4 caused necrosis and caspase-dependent apoptosis in both U937 and Jurkat leukemia cells, which suggests potential utility of HaA4 as a cancer therapeutic agent.

Primary Cultures of Drosophila melanogaster Gut Cells for Studies of Intestinal Stem Cell Regulation

Drosophila melanogaster has been used as a useful model to study development and disease. In this study, we established the primary culture method of Drosophila in the intestine to understand how intestinal stem cells (ISCs) mediate tissue repair during infection and disease. To obtain intestinal cells, we separated intestines from adult flies and isolated single cells by enzymatic treatment. The survival of cultured cells was measured using MTS-analysis. The maximum growth rate of the cells was observed on the 9th day after seeding. In addition, the presence of ISCs and enteroendocrine cells was confirmed by delta and prospero staining. Accordingly, we supposed that Drosophila melanogaster gut cells established in this study are probably useful in studies about intestinal stem cell regulation and various diseases occurring in the intestine.

Anti-inflammatory Effect of Oxya chinensis sinuosa Ethanol Extract in LPS-induced RAW 264.7 Cells

Although the grasshopper Oxya chinensis sinuosa has long been used as food in Korea, there is little data on its functional effects. In this study, we investigated the anti-inflammatory effect of O. c. sinuosa ethanol extract (OCE) in RAW 264.7 mouse macrophage cells treated with lipopolysaccharide (LPS) for induction of inflammation. First, we determined that there is no cytotoxicity at 2,000 μg/ml or less of OCE in RAW 264.7 cells. To evaluate the anti-inflammatory effects of OCE, we investigated expression levels of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-6, and pro-inflammatory enzymes such as inducible nitric oxide synthase (iNOS) and cyclo-oxygenase- 2 (COX-2) in LPS-induced RAW 264.7 cells. In addition, we examined whether OCE could inhibit translocation of NF-κB p65 into the nucleus in LPS induced RAW 264.7 cells. As a result, we found that the mRNA and protein levels of TNF-α and IL-6 decreased in LPS-induced RAW 264.7 cells after treatment with OCE in a dose-dependent manner. In addition, we confirmed a 2,000 ug/ml concentration of OCE inhibited translocation of NF-κB p65 by immunnostaining and Western blot analysis, and a decrease in the protein expression levels of iNOS and COX-2. Accordingly, we suppose that OCE has an anti-inflammatory effect through down-regulation of TNF-α, IL-6, iNOS, and COX-2 related to NF-κB p65 inflammatory signaling pathways.

Characterization of a Novel Fibrinolytic Enzyme, BsfA, from Bacillus subtilis ZA400 in Kimchi Reveals Its Pertinence to Thrombosis Treatment.

Recently, the cardiovascular disease has been widely problematic in humans probably due to fibrin formation via the unbalanced Western style diet. Although direct (human plasmin) and indirect methods (plasminogen activators) have been available, bacterial enzyme methods have been studied because of their cheap and mass production. To detect a novel bacterial fibrinolytic enzyme, 111 bacterial strains with fibrinolytic activity were selected from kimchi. Among them, 14 strains were selected because of their stronger activity than 0.02 U of plasmin. Their 16S rRNA sequence analysis revealed that they belong to Bacillus, Leuconostoc, Propionibacterium, Weissella, Staphylococcus, and Bifidobacterium. The strain B. subtilis ZA400, with the highest fibrinolytic activity, was selected and the gene encoding fibrinolytic enzyme (bsfA) was cloned and expressed in the E. coli overexpression system. The purified enzyme was analyzed with SDS-PAGE, western blot, and MALDI-TOF analyses, showing to be 28.4 kDa. Subsequently, the BsfA was characterized to be stable under various stress conditions such as temperature (4-40°C), metal ions (Mn(2+), Ca(2+), K(2+), and Mg(2+)), and inhibitors (EDTA and SDS), suggesting that BsfA could be a good candidate for development of a novel fibrinolytic enzyme for thrombosis treatment and may even be useful as a new bacterial starter for manufacturing functional fermented foods.

Enantiomeric CopA3 dimer peptide suppresses cell viability and tumor xenograft growth of human gastric cancer cells.

The CopA3 dimer peptide is a coprisin analog that has an anticancer effect against human cancer cells in vitro. In this study, we investigated the anticancer activity of the enantiomeric CopA3 dimer peptide in human gastric cancer cell lines as well as in an in vivo tumor xenograft model. Enantiomeric CopA3 reduced gastric cancer cell viability and exhibited cytotoxicity against cancer cells. Enantiomeric CopA3-induced cell death was mediated by specific interactions with phosphatidylserine and phosphatidylcholine, membrane components that are enriched in cancer cells, in a calcein leakage assay. Moreover, acridine orange/ethidium bromide staining, flow cytometric analysis, and Western blot analysis showed that enantiomeric CopA3 induced apoptotic and necrotic gastric cancer cell death. The antitumor effect was also observed in a mouse tumor xenograft model in which intratumoral inoculation of the peptide resulted in a significant decrease in the SNU-668 gastric cancer tumor volume. In addition, periodic acid-Schiff and hematoxylin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay revealed apoptotic and necrotic cell death in tumor masses treated with greater than 150xa0μg CopA3. Collectively, these results indicate that the enantiomeric CopA3 dimer peptide induces apoptosis and necrosis of gastric cancer cells in vitro and in vivo, indicating that the peptide is a potential candidate for the treatment of gastric cancer, which is a common cause of cancer and cancer deaths worldwide.

Antimicrobial Activity of the Scolopendrasin V Peptide Identified from the Centipede Scolopendra subspinipes mutilans

In a previous study, we analyzed the transcriptome of Scolopendra subspinipes mutilans using next-generation sequencing technology and identified several antimicrobial peptide candidates. One of the peptides, scolopendrasin V, was selected based on the physicochemical properties of antimicrobial peptides using a bioinformatics strategy. In this study, we assessed the antimicrobial activities of scolopendrasin V using the radial diffusion assay and colony count assay. We also investigated the mode of action of scolopendrasin V using flow cytometry. We found that scolopendrasin Vs mechanism of action involved binding to the surface of microorganisms via a specific interaction with lipopolysaccharides, lipoteichoic acid, and peptidoglycans, which are components of the bacterial membrane. These results provide a basis for developing peptide antibiotics.

Immune modulation of glycosaminoglycan derived from P. lewisi in TNF-α stimulated cells

Poecilocoris lewisi (Korean name: “Kwangdaenolinjae”) is a red-striped gold stink bug (insect) which has been used as a crude drug in traditional medicine of East Asia and Korea. In this study, ethanol extract and glycosaminoglycan from P. lewisi (Pl GAG), as an active substance among its components, were investigated for their potential anti-inflammatory actions. They were found to be a potent inducer of nitric oxide (NO) production from calf pulmonary artery endothelial (CPAE) cells and a stimulator of endothelial nitric oxide synthase in a dose-dependent manner. The anti-inflammatory activities were also evaluated by determining the level of adhesion molecules related to atherogenesis and pro-inflammatory cytokines, such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), secretory phospholipase A2, and prostaglandin E2, stimulated by tumor necrosis factor (TNF)-α in human umbilical vein endothelial cells (HUVEC). They also showed inhibitory effects on vascular endothelial growth factor (VEGF) production in HUVECs. Matrix metalloproteinases (MMP-2 and 9) were also inhibited by treatment with this extract or glycosaminoglycan. Furthermore, this GAG showed cytotoxicity against CT-26 colon cancer cells whereas having no cytotoxicity in CHO normal cells. Monosaccharide (amino, acidic, neutral monosaccharides) composition of used GAG was characterized by trimethylsilylated GC–MS analysis method.

Microarray expression profiling of Spodoptera litura in response to oxidative stress

To examine the expression profile of oxidative stress responsive genes in Spodoptera litura, we constructed a cDNA library from S. litura injected with hydrogen peroxide (H(2)O(2)). Using a microarray chip composed of 2,964 cDNAs, we screened gene expression at 1, 3, 5, 7, and 9 h post H(2)O(2) injection. Data were clustered into 15 groups of genes that behave similarly across each time course. Seventy-three genes were identified as being at least twofold up- or downregulated after treatment with H(2)O(2) in S. litura. We constructed expressed sequence tags (ESTs) for genes that changed at least twofold after treatment with H(2)O(2) . The functional classification of these ESTs based on Gene Ontology showed that the ESTs are rich in genes involved in oxidoreductase activity (5.7%), defense (14.3%), cellular process (22.9%), and development (17.1%).