• Journal of Applied Biological Chemistry
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• 제66권
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• pp.221-226
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• 2023

혈소판의 적절한 활성화와 응집이 필요하지만 과도하거나 비정상적인 응집은 뇌졸중, 혈전증, 동맥경화증과 같은 심혈관 질환을 유발할 수 있다. 따라서 이러한 질병을 예방하고 치료하기 위해서는 혈소판 응집을 조절하거나 억제할 수 있는 물질을 찾는 것이 중요하다. 여러 연구에서 Panax 인삼의 특정 ginsenoside 화합물이 혈소판 응집을 억제할 수 있음이 알려져 있다. 이들 화합물 중 Panax ginseng의 Rk3 (G-Rk3)는 혈소판 응집 억제의 기전이 불확실 하기에 이를 밝히기 위한 연구가 필요하다. G-Rk3는 cAMP의 양을 강하게 증가시켰고 cAMP 의존성 kinase의 기질인 VASP 및 IP3R의 인산화를 유도했다. 또한, G-Rk3의 효과는 PI3K/Akt 인산화의 억제를 일으켜 세포 내 과립의 분비를 감소시켰다. 궁극적으로 G-Rk3는 혈소판 응집을 효과적으로 억제하였다. 따라서 우리는 과도한 혈소판 응집으로 인한 심혈관 질환의 예방 또는 치료제로서의 G-Rk3의 가능성을 제안한다.

• 생명과학회지
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• 제25권9호
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• pp.976-983
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• 2015

Achyranthoside C dimethyl ester (ACDE)는 우슬에서 분리한 oleanolic acid glycoside이다. 본 연구에서는 RAW264.7 대식세포에서 ACDE의 항염증 효과를 관찰하고 그 작용 기전을 연구하였다. ACDE는 세포에 독성을 유도하지 않으면서 heme oxygenase-1 (HO-1)의 발현을 유도하였다. ACDE 는 HO-1의 발현에 관여하는 전사인자인 nuclear factor E2-related factor 2 (Nrf2)를 핵으로 이동시켰다. 또한 ACDE에 의한 HO-1의 발현은 phosphatidylinositol 3-kinase (PI-3K) 및 mitogen activated protein kinases (MAPK) 억제제에 의해 감소되었으며, ACDE가 Akt, c-Jun kinase (JNK), extracellular signal regulated kinase (ERK), p38 kinase의 인산화를 유도하였다. 한편 ACDE는 lipopolysaccharide (LPS)로 인한 nitric oxide (NO)의 생성과 inducible NO synthase (iNOS) 발현을 억제하였으며 HO-1 siRNA를 처리했을 때 ACDE가 iNOS의 발현을 억제하지 못하였다. 이상의 결과를 종합해보면, ACDE는 대식세포에서 PI3K/Akt 및 MAPK와 Nrf2 신호전달과정을 통해 HO-1의 발현을 유도함으로써 NO와 같은 염증매개물질의 생성을 억제한다는 것을 알 수 있다. 이러한 연구결과는 ACDE가 항염증제로 사용될 수 있음을 시사한다.

• 한국식품영양과학회지
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• 제45권6호
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• pp.835-842
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• 2016

PI3K/Akt 신호계는 세포 생존의 조절에 필수적인 경로로 대부분 암세포에서 활성이 증대되어 있다. 본 연구에서는 동충하초의 주요 생리활성 물질인 cordycepin에 의한 AGS 인체 위암 세포의 apoptosis 유도에 미치는 PI3K/Akt 신호계의 역할을 조사하였다. 본 연구의 결과에 의하면 cordycepin의 처리 농도의 증가에 따라 AGS 세포의 생존율은 억제되었으며, 이는 apoptosis 유도와 밀접한 관계가 있음을 핵의 형태적 변화와 flow cytometry 분석을 통하여 확인 하였다. 이러한 cordycepin의 apoptosis 유도 효과는 PI3K/Akt 신호계의 활성 저하와 연관성이 있었으며, 세포독성을 나타내지 않는 범위의 PI3K/Akt 신호계 저해제인 LY294002를 cordycepin과 동시 처리하였을 경우, cordycepin에 의한 apoptosis 유발을 더욱 증대시켰다. 그리고 cordycepin에 대한 LY294002의 apoptosis 유발 증대는 caspases (caspase-3, -8 및 -9)의 활성 증가와 poly(ADP-ribose) polymerase 단백질의 분해 증가를 촉진했다. 또한 cordycepin이 처리된 AGS 세포에서 LY294002는 apoptosis 유도에 관여하는 Bax의 발현을 증가시켰고 apoptosis 억제에 관여하는 Bcl-2의 발현은 감소시켰으며, 이는 미토콘드리아 기능 손상과 미토콘드리아에서 세포질로의 cytochrome c 유리를 증대시켰다. 따라서 PI3K/Akt 신호계의 활성 차단은 cordycepin의 항암 활성을 더욱 상승시켰으며, 이는 미토콘드리아 기능 손상과 caspase의 활성 증대를 통하여 이루어짐을 알 수 있었다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2645-2651
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• 2015

Background: The phosphatidylinositol 3'-kinase/Akt (PI3K/Akt) pathway is a key regulator for HER2-overexpressing breast cancer, but data about whether activation of PI3K/Akt is associated with poor prognosis and resistance to trastuzumab therapy is controversial. In this study we investigated predictive and prognostic significance of expression of p27, Akt, PTEN and PI3K, which are components of the PI3K/Akt signaling pathway, in HER2-positive metastatic breast cancer (MBC), retrospectively. Materials and Methods: Fifty-four HER2-positive MBC patients who had received first-line trastuzumab-based therapy were recruited for the study group. All of the patient's breast tissue samples were examined for p27 and Akt expression. In addition, twenty-five patients with sufficient amount of tumor tissue were also examined for PTEN and PI3K expression. p27, Akt, PTEN and PI3K were evaluated by immunohistochemistry and their relationship with patient demographic features, tumor characteristics, response to trastuzumab-based treatment and survival outcomes were analyzed. Results: p27, Akt, PTEN and PI3K were positive in 25.9%, 70.4%, 24% and 96% of the cases, respectively. Nomne were significantly associated with response to trastuzumab and time to progression (TTP). A trend toward statistical significance for longer overall survival (OS) was found for PTEN-positive patients (p=0.058); there was no significant relationship between the other immunohistochemical variables and OS. When we analyzed groups regarding co-expression, the PTEN-negative/Akt-negative group had a significantly lower objective response rate (ORR) (20% vs 80%, p=0.023) and the PTEN-negative/p27-negative and PTEN-negative/Akt-negative groups had significantly lower median OS compared to other patients (26.4 months vs 76.1 months, p=0.005 and 25.6 months vs 52.0 months, p=0.007, respectively). Conclusions: p27, Akt, PTEN and PI3K expression is not statistically significantly associated with ORR, TTP and OS, individually. However, the combined evaluation of p27, Akt and PTEN could be helpful to predict the response to trastuzumab-based therapy and prognosis in HER2-positive MBC.

• Biomolecules & Therapeutics
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• 제22권6호
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• pp.497-502
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• 2014

In the present study, we found that the natural compound arctigenin inhibited hydrogen peroxide-induced reactive oxygen species (ROS) production in rat primary astrocytes. Since hemeoxygenase-1 (HO-1) plays a critical role as an antioxidant defense factor in the brain, we examined the effect of arctigenin on HO-1 expression in rat primary astrocytes. We found that arctigenin increased HO-1 mRNA and protein levels. Arctigenin also increases the nuclear translocation and DNA binding of Nrf2/c-Jun to the antioxidant response element (ARE) on HO-1 promoter. In addition, arctigenin increased ARE-mediated transcriptional activities in rat primary astrocytes. Further mechanistic studies revealed that arctigenin increased the phosphorylation of AKT, a downstream substrate of phosphatidylinositol 3-kinase (PI3K). Treatment of cells with a PI3K-specific inhibitor, LY294002, suppressed the HO-1 expression, Nrf2 DNA binding and ARE-mediated transcriptional activities in arctigenin-treated astrocyte cells. The results collectively suggest that PI3K/AKT signaling pathway is at least partly involved in HO-1 expression by arctigenin via modulation of Nrf2/ARE axis in rat primary astrocytes.

• 대한통합의학회지
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• 제12권1호
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• pp.63-71
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• 2024

Purpose : Skin is the primary barrier to protect the body from various exogenous factors. Among them, UVB exposure can cause the induction of not only excessive inflammatory responses but also the degradation of extracellular matrix (ECM), including collagen and elastin. This study tried to investigate the ameliorative effect of Persicaria perfoliata ethanol extract (PPEE) on UVB-irradiated photodamage through the regulation of activator protein (AP)-1, phosphoinositide 3-kinase (PI3K)/Akt, and mitogen-activated protein kinase (MAPK) signaling molecules in HaCaT cells. Methods : The cytotoxicity of PPEE on HaCaT cells was evaluated by the WST-1 assay. The 80 mJ/cm² of UVB (312 nm) was irradiated on HaCaT cells to induce the photodamage. Western blot analysis was conducted to investigate the protein expression levels of cyclooxygenase (COX)-2, matrix metalloproteinase (MMP)-9, and heme oxygenase (HO)-1 for ameliorative status by PPEE treatment in UVB-exposed HaCaT cells. In addition, the activated status of the inflammatory transcription factor, AP-1, as well as upstream signaling molecules, PI3K/Akt, and MAPK, were also evaluated by Western blot analysis. Results : Any cytotoxic effect was not induced at the concentration up to 200 ㎍/ml by PPEE treatment. Protein expression levels of COX-2 and MMP-9 were significantly down- and up-regulated by PPEE treatment. The inflammatory transcription factor AP-1, stimulated by UVB irradiation, was also significantly attenuated by PPEE treatment. The phosphorylated status of PI3K/Akt and MAPK were mitigated by PPEE treatment in UVB-exposed HaCaT cells. Moreover, PPEE treatment potently accelerated the expression of HO-1 and its transcription factor, nuclear factor-erythroid 2-related factor (Nrf)2, which is known for its anti-inflammatory activity. Conclusion : Consequently, PPEE treatment significantly regulated COX-2 and MMP-9 expressions in UVB-irradiated HaCaT cells. The inflammatory transcription factor AP-1, along with upstream signaling molecules PI3K/Akt and MAPKs, were also attenuated by PPEE treatment in UVB-exposed HaCaT cells. Additionally, PPEE treatment exaggerated HO-1 expression and Nrf2 activation, which might have contributed to the anti-inflammatory activity of PPEE. These results indicate that PPEE could be a candidate for attenuating UVB-induced photodamage in human skin.

• Journal of Applied Biological Chemistry
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• 제64권4호
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• pp.447-451
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• 2021

In this study, we discovered for the first time that linarin, a flavonoid compound, enhances melanin biosynthesis in B16F10 cells, and subsequently elucidated the underlying mechanism of linarin-induced melanogenesis. Linarin showed no cytotoxicity at a concentration of 42 μM and significantly increased intracellular tyrosinase activity and melanin content in B16F10 cells. Mechanistic analysis showed that linarin increased the expression of tyrosinase, tyrosinase-related protein 1 (TRP-1), and microphthalmia-associated transcription factor (MITF) that are related to melanogenesis. Moreover, linarin decreased the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (AKT). Finally, we evaluated the effect of the structure-activity relationship of linarin and its aglycone on melanogenesis. The results indicated that linarin enhances the expression of melanogenic proteins by activating MITF expression via the modulation of mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), and protein kinase B signaling pathways in B16F10 cells, thereby enhancing melanogenesis.

• Molecules and Cells
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• 제26권3호
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• pp.285-290
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• 2008

Estrogen-induced proliferation in estrogen receptor (ER)-positive breast cancer cells is primarily mediated through two distinct intracellular receptors, $ER{\alpha}$ and $ER{\beta}$. Although tumor necrosis factor alpha ($TNF{\alpha}$) and $E2/ER{\alpha}$ are known to exert opposing effects on cell proliferation in MCF-7 cells, the mechanism by which $TNF{\alpha}$ antagonizes $E2/ER{\alpha}$-mediated cell proliferation is not well understood. The present study suggests that reduced cell survival in response to $TNF{\alpha}$ treatment in MCF-7 cells may be associated with the down-regulation of $ER{\alpha}$ protein. The decrease in $ER{\alpha}$ protein level was accompanied by an inhibition of $ER{\alpha}$ gene transcription. Cell viability was decreased synergistically by the combined treatment with $ER{\alpha}$-siRNA and $TNF{\alpha}$. Furthermore, pretreatment of cells with the PI3-kinase (PI3K)/ Akt inhibitor, LY294002, markedly enhanced $TNF{\alpha}$-induced down-regulation of the $ER{\alpha}$ protein, suggesting that the PI3K/Akt pathway might be involved in control of the $ER{\alpha}$ level. Moreover, down-regulation of $ER{\alpha}$ by $TNF{\alpha}$ was not inhibited in cells that were pretreated with the proteasome inhibitors, MG132 and MG152, which suggests that proteasome-dependent proteolysis does not significantly influence $TNF{\alpha}$-induced down-regulation of $ER{\alpha}$ protein. In contrast, the effect of the PI3K/Akt inhibitor on $ER{\alpha}$ was blocked in cells that were treated with LY294002 in the presence of the proteasome inhibitors. Collectively, our findings show that the $TNF{\alpha}$ may partly regulate the growth of MCF-7 breast cancer cells through the down-regulation of $ER{\alpha}$ expression, which is primarily mediated by a PI3K/Akt signaling.

• The Korean Journal of Pain
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• 제34권2호
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• pp.176-184
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• 2021

Background: Diabetes-related neuropathic pain frequently occurs, and the underpinning mechanism remains elusive. The periaqueductal gray (PAG) exhibits descending inhibitory effects on central pain transmission. The current work aimed to examine whether inflammatory cytokines regulate mechanical allodynia and thermal hyperalgesia induced by diabetes through the phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathway in the PAG. Methods: Streptozotocin (STZ) was administered intraperitoneally to mimic allodynia and hyperalgesia evoked by diabetes in rats. Behavioral assays were carried out for determining mechanical pain and thermal hypersensitivity. Immunoblot and ELISA were performed to examine PAG protein amounts of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), as well as their corresponding receptors in STZ rats, and the expression of PI3K/protein kinase B (Akt)/mTOR signaling effectors. Results: Increased PAG p-PI3K/p-Akt/p-mTOR protein amounts were observed in STZ-induced animals, a PI3K-mTOR pathway inhibition in the PAG attenuated neuropathic pain responses. Moreover, the PAG concentrations of IL-1β, IL-6, and TNF-α and their receptors (namely, IL-1R, IL-6R, and tumor necrosis factor receptor [TNFR] subtype TNFR1, respectively) were increased in the STZ rats. Additionally, inhibiting IL-1R, IL-6R, and TNFR1 ameliorated mechanical allodynia and thermal hyperalgesia in STZ rats, alongside the downregulation of PI3K-mTOR signaling. Conclusions: Overall, the current study suggests that upregulated proinflammatory cytokines and their receptors in the PAG activate PI3K-mTOR signaling, thereby producing a de-inhibition effect on descending pathways in modulating pain transmission, and eventually contributing to neuropathic pain.

• BMB Reports
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• 제42권2호
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• pp.119-124
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• 2009

PI(3,4,5)$P_3$ produced by the activated PI3-kinase is a key lipid second messenger in cell signaling downstream of insulin. Skeletal muscle and kidney-enriched inositol phosphatase (SKIP) identified as a 5'-inositol phosphatase that hydrolyzes PI(3,4,5) $P_3$ to PI(3,4)$P_2$, negatively regulates the insulin-induced glycogen synthesis in skeletal muscle. However the mechanism by which this occurs remains unclear. To elucidate the function of SKIP in glycogen synthesis, we employed RNAi techniques to knockdown the SKIP gene in differentiating C2C12 myoblasts. Insulininduced phosphorylation of Akt (protein kinase B) and GSK-3$\beta$ (Glycogen synthase kinase), subsequent dephosphorylation of glycogen synthase and glycogen synthesis were increased by inhibiting the expression of SKIP, whereas the insulin-induced glycogen synthesis was decreased by overexpression of WT-SKIP. Our results suggest that SKIP plays a negative regulatory role in Akt/ GSK-3$\beta$/GS (glycogen synthase) pathway leading to glycogen synthesis in myocytes.