• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.470-476
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• 2017

Changes in the mammalian target of the rapamycin (mTOR) signaling proteins have been observed in many types of cancer. Accordingly, these proteins have recently become an exciting new target for molecular therapeutics. This study examined the expression of an activated mTOR signaling protein in patients with colorectal adenocarcinoma (CRAC) and colorectal adenoma lesion. Immunohistochemical analysis was performed on human CRAC and adenoma for the mTOR signaling components, including mTOR, phosphorylation, and activation of S6 kinase (p70-S6K), S6 ribosomal protein (S6), and eukaryotic initiation factor 4E-binding protein (4EBP1). A total of 100 cases with colorectal adenocarcinoma (CARC; N=40), adenoma with high-grade intraepithelial neoplasms (HIN; N=30), and adenoma with low-grade intraepithelial neoplasms (LIN; N=30) were enrolled in this study. p-mTOR expression was observed in 30 cases of the CRAC tissues (75%), 9 cases of adenoma with HIN (30%), and 2 cases of adenoma with LIN (7%). In addition, p-S6 expression was observed in 22 cases of CRAC tissues (55%), 8 cases of adenoma with HIN (27%), and 3 cases of adenoma with LIN (10%). A significant correlation was observed among the p-mTOR, p-S6 expression, and the adenoma-carcinoma sequence. Interestingly, the p-S6 protein was activated more in early CRAC than in advanced CRAC.

• Biomolecules & Therapeutics
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• v.26 no.2
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• pp.115-120
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• 2018

Chronic cerebral hypoperfusion (CCH), which is associated with onset of vascular dementia, causes cognitive impairment and neuropathological alterations in the brain. In the present study, we examined the neuroprotective effect of duloxetine (DXT), a potent and balanced serotonin/norepinephrine reuptake inhibitor, on CCH-induced neuronal damage in the hippocampal CA1 region using a rat model of permanent bilateral common carotid arteries occlusion. We found that treatment with 20 mg/kg DXT could attenuate the neuronal damage, the reduction of phosphorylations of mTOR and p70S6K as well as the elevations of $TNF-{\alpha}$ and $IL-1{\beta}$ levels in the hippocampal CA1 region at 28 days following CCH. These results indicate that DXT displays the neuroprotective effect against CCH-induced hippocampal neuronal death, and that neuroprotective effect of DXT may be closely related with the attenuations of CCH-induced decrease of mTOR/p70S6K signaling pathway as well as CCH-induced neuroinflammatory process.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.105-110
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• 2018

Melittin is the main component of apitoxin (bee venom) that has been reported to have anti-inflammatory and anti-cancer effects. Herein, we demonstrated that inhibition of epithelial-mesenchymal transition (EMT) by melittin causes suppression of cancer cell migration and invasion. Melittin significantly suppressed the epidermal growth factor (EGF)-induced cell migration and invasion in lung cancer cells. Moreover, melittin up-regulated the expression of epithelial marker protein, E-cadherin, and down-regulated the expression of EMT related proteins, vimentin and fibronectin. Mechanistic studies revealed that melittin markedly suppressed the expression of EMT mediated transcription factors, ZEB2, Slug, and Snail. The EGF-induced phosphorylation of AKT, mTOR, P70S6K, and 4EBP1 was also inhibited by melittin, but not that of ERK and JNK. Therefore, the inhibitory effect of melittin on migration and invasion of lung cancer cells may be associated with the inhibition of EMT via blocking of the AKT-mTOR-P70S6K-4EBP1 pathway.

• Preventive Nutrition and Food Science
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• v.20 no.4
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• pp.238-245
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• 2015

A non-protein amino acid, L-ornithine (Orn), has been shown to stimulate the urea cycle and tissue protein synthesis in the liver. The purpose of the current study was to assess whether Orn affects the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) pathway, which is involved in protein synthesis. Primary cultured cells isolated from Wistar rat liver were incubated in an amino acid-free medium, followed by addition of Orn for 3 h. The cell lysate was subjected to immunoblotting to evaluate the phosphorylation of downstream targets of mTORC1, including p70S6K, S6, and 4EBP1. To assess the involvement of mTORC1 for the effect of Orn, the cells were pretreated with the mTOR inhibitor rapamycin before the addition of Orn and the cell lysate was subjected to immunoblotting. We next examined whether the effects of Orn were exerted in vivo. Orn was orally administered to 18 h food-deprived rats, the blood and the livers were collected at 1 and 3 h after administration for immunoblotting. Orn treatment for primary cultured cells for 3 h enhanced the phosphorylation of p70S6K, S6, and 4EBP1. In addition, rapamycin blocked the effects of Orn completely (p70S6K and S6) or partially (4EBP1). The oral administration of Orn to the rat also augmented the phosphorylation of mTORC1 downstream targets notably in S6 at 1 h. Our findings demonstrate that Orn has the potential to induce the phosphorylation of downstream targets of mTORC1 in the rat liver. This may be mediated by the augmentation of mTORC1 activity.

• BMB Reports
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• v.52 no.7
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• pp.424-433
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• 2019

Autism spectrum disorder (ASD) is a complex neurodevelopmental monogenic disorder with a strong genetic influence. Idiopathic autism could be defined as a type of autism that does not have a specific causative agent. Among signalling cascades, mTOR signalling pathway plays a pivotal role not only in cell cycle, but also in protein synthesis and regulation of brain homeostasis in ASD patients. The present review highlights, underlying mechanism of mTOR and its role in altered signalling cascades as a triggering factor in the onset of idiopathic autism. Further, this review discusses how distorted mTOR signalling pathway stimulates truncated translation in neuronal cells and leads to downregulation of protein synthesis at dendritic spines of the brain. This review concludes by suggesting downstream regulators such as p70S6K, eIF4B, eIF4E of mTOR signalling pathway as promising therapeutic targets for idiopathic autistic individuals.

• Korean Journal of Pharmacognosy
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• v.54 no.1
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• pp.1-8
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• 2023

The skin is an important barrier that protects the body from harmful environments such as UV rays. When the skin is repeatedly stimulated, such as UV rays, ROS and pro-inflammatory cytokines are overproduced. As a result, the proteins and nucleic acids that make up the skin are damaged, and aging occurs. Esculetin is known to have anti-inflammatory, antioxidant and UV-induced MMP-1 inhibitory effects. However, the inhibitory effect of MMP-1 on TNF-α-induced fibroblasts is not known. Therefore, in this study, the MMP-1 inhibitory effect of esculetin was confirmed in TNF-α-induced fibroblasts. As a result of confirming the cytotoxicity of esculetin in Hs68 cells by MTT assay, there was no significant toxicity up to 200 µM. As a result of real-time PCR and ELISA, it was confirmed that esculetin inhibited the expression of MMP-1. Esculetin did not inhibit MAPK (ERK, JNK, p38) phosphorylation, but inhibited phosphorylation of the mTOR-p70S6k signaling pathway. In addition, it was confirmed that the phosphorylation of the transcription factor NF-κB was inhibited. These results suggest that esculetin has potential as an anti-aging material.

• BMB Reports
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• v.39 no.5
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• pp.626-635
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• 2006

Lysophosphatidic acid acyltransferase (LPAAT) is an intrinsic membrane protein that catalyzes the synthesis of phosphatidic acid (PA) from lysophosphatidic acid (LPA). It is well known that LPAAT is involved in lipid biosynthesis, while its role in tumour progression has been of emerging interest in the last few years. To date, seven members of the LPAAT gene family have been found in human. Here we report a novel LPAAT member, designated as LPAAT-theta, which was 2728 base pairs in length and contained an open reading frame (ORF) encoding 434 amino acids. The LPAAT-theta gene consisted of 12 exons and 11 introns, and mapped to chromosome 4q21.23. LPAAT-theta was ubiquitously expressed in 18 human tissues by RT-PCR analysis. Subcellular localization of LPAAT-theta-EGFP fusion protein revealed that LPAAT-theta was distributed primarily in the endoplasmic reticulum (ER) of COS-7 cells. Furthermore, we found that the overexpression of LPAAT-theta can induce mTOR-dependent p70S6K phosphorylation on Thr389 and 4EBP1 phosphorylation on Ser65 in HEK293T cells.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2985-2989
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• 2014

Autophagy is a self-digestion process in which intracellular structures are degraded in response to stress. Notably, prolonged autophagy leads to cell death. In this study, we investigated whether CX-4945, an orally available protein kinase 2 (CK2) inhibitor, induces autophagic cell death in human cervical cancer-derived HeLa cells and in human prostate cancer-derived LNCaP cells. CX-4945 treatment of both cell lines resulted in the formation of autophagosomes, in the conversion of microtubule-associated protein 1 light chain 3 (LC3), and in down-regulation of the Akt-mammalian target of rapamycin (mTOR)-p70 ribosomal protein S6 kinase (S6K) signaling cascade. Thus, pharmacologic inhibition of CK2 by CX-4945 induced autophagic cell death in human cancer cells by down-regulating Akt-mTOR-S6K. These results suggest that autophagy-inducing agents have potential as anti-cancer drugs.

• BMB Reports
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• v.55 no.2
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• pp.92-97
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• 2022

Lysine methylation is one of the most important histone modifications that modulate chromatin structure. In the present study, the roles of the histone lysine demethylases JMJD2a and LSD1 in CK2 downregulation-mediated senescence were investigated. The ectopic expression of JMJD2a and LSD1 suppressed the induction of senescence-associated β-galactosidase activity and heterochromatin foci formation as well as the reduction of colony-forming and cell migration ability mediated by CK2 knockdown. CK2 downregulation inhibited JMJD2a and LSD1 expression by activating the mammalian target of rapamycin (mTOR)-ribosomal p70 S6 kinase (p70S6K) pathway. In addition, the down-regulation of JMJD2a and LSD1 was involved in activating the p53-p21^Cip1/WAF1-SUV39h1-trimethylation of the histone H3 Lys9 (H3K9me3) pathway in CK2-downregulated cells. Further, CK2 downregulation-mediated JMJD2a and LSD1 reduction was found to stimulate the dimethylation of Lys370 on p53 (p53K370me2) and nuclear import of SUV39h1. Therefore, this study indicated that CK2 downregulation reduces JMJD2a and LSD1 expression by activating mTOR, resulting in H3K9me3 induction by increasing the p53K370me2-dependent nuclear import of SUV39h1. These results suggest that CK2 is a potential therapeutic target for age-related diseases.

• BMB Reports
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• v.52 no.1
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• pp.70-85
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• 2019

Reduction of insulin/insulin-like growth factor 1 (IGF1) signaling (IIS) extends the lifespan of various species. So far, several longevity mouse models have been developed containing mutations related to growth signaling deficiency by targeting growth hormone (GH), IGF1, IGF1 receptor, insulin receptor, and insulin receptor substrate. In addition, p70 ribosomal protein S6 kinase 1 (S6K1) knockout leads to lifespan extension. S6K1 encodes an important kinase in the regulation of cell growth. S6K1 is regulated by mechanistic target of rapamycin (mTOR) complex 1. The v-myc myelocytomatosis viral oncogene homolog (MYC)-deficient mice also exhibits a longevity phenotype. The gene expression profiles of these mice models have been measured to identify their longevity mechanisms. Here, we summarize our knowledge of long-lived mouse models related to growth and discuss phenotypic characteristics, including organ-specific gene expression patterns.