• 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.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.774-782
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• 2024

This study aimed to elucidate the anti-colon cancer mechanism of ginsenoside Rg1 in vitro and in vivo. Cell viability rate was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium assay. The inhibitory effect of ginsenoside Rg1 against CT26 cell proliferation gradually increased with increasing concentration. The in vivo experiments also demonstrated an antitumor effect. The monodansylcadaverine (MDC), transmission electron microscopy (TEM), and expression of autophagy marker proteins confirmed that ginsenoside Rg1 induced autophagy in vitro. Ginsenoside Rg1 induced autophagy death of CT26 cells, but this effect could be diminished by autophagy inhibitor (3-methyladenine, 3-MA). Additionally, in a xenograft model, immunohistochemical analysis of tumor tissues showed that the LC3 and Beclin-1 proteins were highly expressed in the tumors from the ginsenoside Rg1-treated nude mice, confirming that ginsenoside Rg1 also induced autophagy in vivo. Furthermoer, both in vivo and in vitro, the protein expressions of p-Akt, p-mTOR, and p-p70S6K were inhibited by ginsenoside Rg1, which was verified by Akt inhibitors. These results indicated that the mechanism of ginsenoside Rg1 against colon cancer was associated with autophagy through inhibition of the Akt/mTOR/p70S6K signaling pathway.

• 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.53 no.7
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• pp.373-378
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• 2020

Phosphorylation of the signaling component by protein kinase often leads to a kinase cascade or feedback loop. 3-Phosphoinositide-dependent kinase 1 (PDK1) signaling pathway diverges into various kinases including Akt and p70 S6 kinase (p70S6k). However, the PDK1 feedback mechanism remains elusive. Here, we demonstrated that UNC-51-like kinase (ULK1), an autophagy initiator kinase downstream of mechanistic target of rapamycin (mTOR), directly phosphorylated PDK1 on serine 389 at the linker region. Furthermore, our data showed that this phosphorylation affected the kinase activity of PDK1 toward downstream substrates. These results suggest a possible negative feedback loop between PDK1 and ULK1.

• Biomolecules & Therapeutics
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• v.19 no.1
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• pp.21-26
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• 2011

Ceramide is an important lipid mediator of extracellular signals that control various cellular functions, including apoptosis. In this study, we showed that ceramide induced apoptosis in U373MG human glioblastoma cells associated with G1 cell cycle arrest. Treatment of cells with ceramide increased proapoptotic Bax expression and inhibited the expression of antiapoptotic Bcl-2 and Bcl-xL Ceramide also downregulated cyclin E, cyclin D1, cdk 2, and cdk4 which are involved in regulating cell cycle. In addition, ceramide suppressed phosphorylation of Akt, Bad, p70 S6 kinase, and 4E-BP1, suggesting the involvement of Akt/mTOR signaling pathway. Additionally, okadaic acid, an inhibitor of protein phosphatase 2A, partially blocked the ceramide mediated inhibition of phosphorylation of Akt and 4E-BP1. These results suggest that ceramide induces apoptosis in U373MG glioblastoma cells by regulating multiple signaling pathways that involve cell cycle arrest associated with Akt signaling pathway.

• The Journal of Korean Medicine
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• v.38 no.2
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• pp.7-14
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• 2017

Objectives: This study evaluated the effect of aqueous extract from roots of Siberian ginseng on mTORC1 pathway. Methods: mTORC1 activity was measured by the phosphorylation status of p70 S6 kinase (S6K) in HeLa cells as well as the brain, liver and muscle tissues in diabetic db/db mice. Autophagy induction after the treatment of Siberian ginseng extract was evaluated by monitoring the conversion of cytoplasmic LC3I into lipidated LC3II in cultured human HeLa GFP-LC3 cells. Cell cycle analysis was performed in HeLa cells treated with Siberian ginseng using flow cytometry. Results: Among >2,800 plant products used for oriental medicine, Siberian ginseng was found to inhibit mTORC1 to phosphorylate S6 kinsase (S6K) in HeLa cells as well as the brain, liver and muscle tissues in diabetic db/db mice. Siberian ginseng-mediated mTORC1 activity was reversible unlike the prolonged suppression of mTORC1 by rapamycin when HeLa cells were grown in fresh media after the removal of the inhibitors. Siberian ginseng extract at concentrations to inhibit mTORC1 was not overly cytotoxic in cultured HeLa cells whereas rapamycin was obviously cytotoxic. The conversion of cytoplasmic LCI into lipidated LCII was increased by fivefold in HeLa GFP-LC3 cells treated with Siberian ginseng extract. Progression of cell cycle was attenuated at G2/M phase by the treatment of Siberian ginseng extract. Conclusions: These results suggest that the aqueous extract of Siberian ginseng possibly plays a good therapeutic role in various diseases involving mTORC1 signaling.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.9
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• pp.5017-5021
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• 2013

Objective: MicroRNAs (miRNAs) are a small class of non-coding, single-stranded RNAs with a critical role in genesis and maintenance of renal cancer mainly through binding to 3'-untranslated regions (3'UTR) of target mRNAs, which causes a block of translation and/or mRNA degradation. The aim of the present study was to investigate the potential effects of miR-122 in human renal cell carcinomas. Methods: The expression level of miR-122 was quantified by qRT-PCR. MTT, colony formation, invasion and migration assays were used to explore the potential functions of miR-122 in human renal cell carcinoma cells. Results: Cellular growth, invasion and migration in two A498 and 786-O cells were significantly increased after miR-122 transfection. Further experiments demonstrated that overexpression of miR-122 resulted in the increase of phospho-Akt (Ser473) and phospho-mTOR (Ser2448), then activation of mTOR targets, p70S6K and 4E-BP1. Conclusions: The up-regulation of miR-122 may play an important role in the progress of renal cancer through activating PI3K/Akt signal pathway and could be a potential molecular target for anti-cancer therapeutics.