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

• IMMUNE NETWORK
• /
• 제11권4호
• /
• pp.223-226
• /
• 2011

Although exercise-induced growth factors such as Insulin-like growth factor-I (IGF-I) are known to affect various aspects of physiology in skeletal muscle cells, the molecular mechanism by which IGF-I modulates anti-inflammatory effects in these cells is presently unknown. Here, we showed that IGF-I stimulation suppresses the expression of toll-like receptor 4 (TLR4), a key innate immune receptor. A pharmacological inhibitor study further showed that PI3K/Akt signaling pathway is required for IGF-I-mediated negative regulation of TLR4 expression. Furthermore, IGF-I treatment reduced the expression of various NF-${\kappa}B$-target genes such as TNF-${\alpha}$ and IL-6. Taken together, these findings indicate that the anti-inflammatory effect of exercise may be due, at least in part, to IGF-I-induced suppression of TLR4 and subsequent downregulation of the TLR4-dependent inflammatory signaling pathway.

• 한국발생생물학회지:발생과생식
• /
• 제24권2호
• /
• pp.113-123
• /
• 2020

Metformin has been widely used as an antidiabetic drug, and reported to inhibit cell proliferation in many cancers including non-small cell lung cancer (NSCLC). In NSCLC cells, metformin suppresses PI3K/AKT/mTOR signaling pathway, but effect of metformin on RAS/RAF/MEK/ERK signaling pathway is controversial; several studies showed the inhibition of ERK activity, while others demonstrated the activation of ERK in response to metformin exposure. Metformin-induced activation of ERK is therapeutically important, since metformin could enhance cell proliferation through RAS/RAF/MEK/ERK pathway and lead to impairment of its anticancer activity suppressing PI3K/AKT/mTOR pathway, requiring blockade of both signaling pathways for more efficient antitumor effect. The present study tested the combination therapy of metformin and trametinib by monitoring the alterations of regulatory effector proteins of cell signaling pathways and the effect of the combination on cell viability in NCI-H2087 NSCLC cells with NRAS and BRAF mutations. We show that metformin alone blocks PI3K/AKT/mTOR signaling pathway but induces the activation and phosphorylation of ERK. The combination therapy synergistically decreased cell viability in treatment with low doses of two drugs, while it gave antagonistic effect with high doses. These findings suggest that the efficacy of metformin and trametinib combination therapy may depend on the alteration of ERK activity induced by metformin and specific cellular context of cancer cells.

• Oncology Letters
• /
• 제42권5호
• /
• pp.2149-2158
• /
• 2019

Primary refractory acute myeloid leukemia (AML) and early recurrence of leukemic cells are among the most difficult hurdles to overcome in the treatment of AML. Moreover, uncertainties surrounding the molecular mechanism underlying refractory AML pose a challenge when it comes to developing novel therapeutic drugs. However, accumulating evidence suggests a contribution of phosphatase and tensin homolog (PTEN)/protein kinase B (AKT) signaling to the development of refractory AML. To assess PTEN/AKT signaling in AML, two types of AML cell lines were evaluated, namely control HL60 cells and KG1α cells, a refractory AML cell line that is resistant to idarubicin and cytarabine (AraC) treatment. Changes in the expression level of glycolysis- and mitochondrial oxidative phosphorylation-related genes and proteins were evaluated by reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. The mitochondrial oxygen consumption and extracellular acidification rates were measured using an XF24 analyzer. CCK8 assay and Annexin V/PI staining were used to analyze cell viability and cellular apoptosis, respectively. The PTEN protein was found to be depleted, whereas AKT phosphorylation levels were elevated in KG1α cells compared with HL60 cells. These changes were associated with increased expression of glucose transporter 1 and hexokinase 2, and increased lactate production. AKT inhibition decreased the proliferation of KG1α cells and decreased extracellular acidification without affecting HL60 cells. Notably, AKT inhibition increased the susceptibility of KG1α cells to chemotherapy with idarubicin and AraC. Taken together, the findings of the present study indicate that activation of AKT by PTEN deficiency sustains the refractory AML status through enhancement of glycolysis and mitochondrial respiration, effects that may be rescued by inhibiting AKT activity.

• Journal of Ginseng Research
• /
• 제44권3호
• /
• pp.435-441
• /
• 2020

Background: As a process of aging, skeletal muscle mass and function gradually decrease. It is reported that ginsenoside Rb1 and Rb2 play a role as AMP-activated protein kinase activator, resulting in regulating glucose homeostasis, and Rb1 reduces oxidative stress in aged skeletal muscles through activating the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. We examined the effects of Rb1 and Rb2 on differentiation of the muscle stem cells and myotube formation. Methods: C2C12 myoblasts treated with Rb1 and/or Rb2 were differentiated and induced to myotube formation, followed by immunoblotting for myogenic marker proteins, such as myosin heavy chain, MyoD, and myogenin, or immunostaining for myosin heavy chain or immunoprecipitation analysis for heterodimerization of MyoD/E-proteins. Results: Rb1 and Rb2 enhanced myoblast differentiation through accelerating MyoD/E-protein heterodimerization and increased myotube hypertrophy, accompanied by activation of Akt/mammalian target of rapamycin signaling. In addition, Rb1 and Rb2 induced the MyoD-mediated transdifferentiation of the rhabdomyosarcoma cells into myoblasts. Furthermore, co-treatment with Rb1 and Rb2 had synergistically enhanced myoblast differentiation through Akt activation. Conclusion: Rb1 and Rb2 upregulate myotube growth and myogenic differentiation through activating Akt/mammalian target of rapamycin signaling and inducing myogenic conversion of fibroblasts. Thus, our first finding indicates that Rb1 and Rb2 have strong potential as a helpful remedy to prevent and treat muscle atrophy, such as age-related muscular dystrophy.

• 한국식품과학회지
• /
• 제54권3호
• /
• pp.288-296
• /
• 2022

본 연구에서는 우선 진피 열수 추출물의 in vitro 항산화능을 평가하기 위해 total polyphenol, total flavonoid 함량, DPPH 및 ABTS radical 소거능을 분석한 후, 150 mM/60% ethanol로 유발한 급성 위염 동물 실험을 진행하여 급성 위염 완화 효과를 검증하였다. 약물투여군의 혈청 내 ROS와 MPO 수준, 조직 내 MDA 수준의 유의성 있는 감소를 확인하였으며, western blot을 통해 NOX2와 p22^phox를 포함한 산화적 스트레스 관련 단백질을 억제하였고, PI3K/Akt/NF- κB 신호 전달 경로를 통한 염증성 단백질의 현저한 감소를 확인하였다. 따라서 이러한 결과는 진피 열수 추출물이 급성 위염에 대한 완화 효과를 나타냈으며, 위염 및 천연 치료제의 후보 소재로서 가능성이 있다고 판단된다. 또한, 향후 만성 위염, 위암과 같은 위장 질환에 관한 추가 연구에서 진피 열수 추출물의 활용 가능성을 시사한다.

• Journal of Ginseng Research
• /
• 제47권1호
• /
• pp.106-116
• /
• 2023

Background: Pirarubicin (THP) is an anthracycline antibiotic used to treat various malignancies in humans. The clinical usefulness of THP is unfortunately limited by its dose-related cardiotoxicity. Ginsenoside F1 (GF1) is a metabolite formed when the ginsenosides Re and Rg1 are hydrolyzed. However, the protective effects and underlying mechanisms of GF1 on THP-induced cardiotoxicity remain unclear. Methods: We investigated the anti-apoptotic and anti-oxidative stress effects of GF1 on an in vitro model, using H9c2 cells stimulated by THP, plus trigonelline or AKT inhibitor imidazoquinoxaline (IMQ), as well as an in vivo model using THP-induced cardiotoxicity in rats. Using an enzyme-linked immunosorbent test, the levels of malondialdehyde (MDA), brain natriuretic peptide (BNP), creatine kinase (CK-MB), cardiac troponin (c-TnT), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione (GSH) were determined. Nuclear factor (erythroid-derived2)-like 2 (Nrf2) and the expression of Nrf2 target genes, including heme oxygenase-1 (HO-1), glutathione-S-transferase (Gst), glutamate-cysteine ligase modifier subunit (GCLM), and expression levels of AKT/Bcl-2 signaling pathway proteins were detected using Western blot analysis. Results: THP-induced myocardial histopathological damage, electrocardiogram (ECG) abnormalities, and cardiac dysfunction were reduced in vivo by GF1. GF1 also decreased MDA, BNP, CK-MB, c-TnT, and LDH levels in the serum, while raising SOD and GSH levels. GF1 boosted Nrf2 nuclear translocation and Nrf2 target gene expression, including HO-1, Gst, and GCLM. Furthermore, GF1 regulated apoptosis by activating AKT/Bcl-2 signaling pathways. Employing Nrf2 inhibitor trigonelline and AKT inhibitor IMQ revealed that GF1 lacked antioxidant and anti-apoptotic effects. Conclusion: In conclusion, GF1 was found to alleviate THP-induced cardiotoxicity via modulating Nrf2 and AKT/Bcl-2 signaling pathways, ultimately alleviating myocardial oxidative stress and apoptosis.

• 한국식품영양과학회지
• /
• 제46권4호
• /
• pp.417-425
• /
• 2017

벌사상자는 여성의 생식기 질환이나 화농성 피부염에 주로 사용되어온 한약재로, 최근 들어 암과 관련된 연구가 많이 이루어짐에 따라 벌사상자의 항암 효과에 대한 관심이 높아지고 있다. 벌사상자의 대표적인 성분인 osthole, xanthotoxol 등은 벤젠고리 화합물로 에탄올과 같은 유기용매에 잘 용해된다. 이에 따라 본 연구에서는 AGS 위암세포에서 벌사상자 에탄올 추출물(CME)에 대한 세포주기 정지 유도 효과를 확인하고자 하였다. CME 처리에 의한 AGS 위암세포의 증식 억제 유도 효과 및 세포독성 효과를 확인하기 위하여 MTT assay와 LDH release assay를 실시한 결과, 농도 및 시간 의존적으로 세포생존율이 감소하였으며, 농도 의존적인 세포독성 효과를 확인하였다. 또한, CME의 농도가 증가할수록 AGS 위암세포의 형태학적 변화가 관찰되었다. 이러한 세포증식 억제 유도 효과가 세포주기 정지에 의한 것인지 확인하기 위하여 CME를 농도별로 24시간 동안 처리한 후 세포주기를 측정하였다. 그 결과 G1기의 세포가 농도 의존적으로 증가함을 확인하였다. 그리고 CME의 처리가 세포주기와 관련된 단백질에 미치는 영향을 알아보기 위하여 western blot analysis를 실시하여 G1기 세포주기 정지와 관련된 신호 단백질들의 발현 변화를 확인하였다. 그 결과 CME의 처리가 세포 증식과 분열에 중요한 역할을 하는 p-Akt와 p-GSK-$3{\beta}$의 발현을 저해하는 것을 확인하였고, 이에 따라 p53의 발현과 활성이 증가하여 p21의 발현이 증가함을 확인하였다. 또한, p21의 증가에 따른 cyclin E의 발현 감소와 CDK2의 비활성화 상태인 p-CDK(T14), p-CDK(Y15)의 발현 증가를 확인하였다. 이와 같은 CME의 세포주기 억제 유도 효과가 일어나는 신호경로를 확인하기 위하여 LY294002(PI3K/Akt 저해제), BIO(GSK-$3{\beta}$ 저해제), Pifithrin-${\alpha}$(p53 저해제)를 CME와 각각 또는 병행 처리한 후 MTT assay, 세포주기 측정, western blot analysis를 진행하였다. 그 결과 LY294002의 처리는 CME 처리군과 유사하게 세포생존율을 저해시키고 G1기 정지를 유도했으며, 세포주기 단백질을 조절하였다. 또한, GSK-$3{\beta}$와 p53 저해제를 처리하였을 때 CME를 병행 처리했음에도 불구하고 세포증식 억제나 G1기 정지와 같은 항암 효과가 나타나지 않았으며, 관련 신호경로 단백질의 변화도 관찰되지 않았다. 이러한 결과는 CME의 처리가 Akt/GSK-$3{\beta}$/p53 신호경로를 조절하여 cyclin E의 발현을 감소시키고 CDK2의 활성을 억제함으로써 G1기 세포주기 정지를 유도함을 확인하였다.

• Parasites, Hosts and Diseases
• /
• 제53권4호
• /
• pp.371-377
• /
• 2015

Trichomonas vaginalis induces proinflammation in cervicovaginal mucosal epithelium. To investigate the signaling pathways in $TNF-{\alpha}$ production in cervical mucosal epithelium after T. vaginalis infection, the phosphorylation of PI3K/AKT and MAPK pathways were evaluated in T. vaginalis-infected SiHa cells in the presence and absence of specific inhibitors. T. vaginalis increased $TNF-{\alpha}$ production in SiHa cells, in a parasite burden-dependent and incubation time-dependent manner. In T. vaginalis-infected SiHa cells, AKT, ERK1/2, p38 MAPK, and JNK were phosphorylated from 1 hr after infection; however, the phosphorylation patterns were different from each other. After pretreatment with inhibitors of the PI3K/AKT and MAPK pathways, $TNF-{\alpha}$ production was significantly decreased compared to the control; however, $TNF-{\alpha}$ reduction patterns were different depending on the type of PI3K/MAPK inhibitors. $TNF-{\alpha}$ production was reduced in a dose-dependent manner by treatment with wortmannin and PD98059, whereas it was increased by SP600125. These data suggested that PI3K/AKT and MAPK signaling pathways are important in regulation of $TNF-{\alpha}$ production in cervical mucosal epithelial SiHa cells. However, activation patterns of each pathway were different from the types of PI3K/MAPK pathways.

• Archives of Pharmacal Research
• /
• 제27권1호
• /
• pp.68-76
• /
• 2004

Mistletoe lectin has been reported to induce apoptosis in different cancer cell lines in vitro and to show antitumor activity against a variety of tumors in animal models. We previously demonstrated the Korean mistletoe lectin (Viscum album var. coloratum, VCA)-induced apoptosis by down-regulation of Bcl-2 and telomerase activity and by up-regulation of Bax through p53- and p21-independent pathway in hepatoma cells. In the present study, we observed the induction of apoptotic cell death through activation of caspase-3 and the inhibition of telomerase activity through transcriptional down-regulation of hTERT in the VCA-treated A253 cells. We also observed the inhibition of telomerase activity and induction of apoptosis resulted from dephosphorylation of Akt in the survival signaling pathways. In addition, combining VCA with the inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) upstream of Akt, wortmannin and LY294002 showed an additive inhibitory effect of telomerase activity. In contrast, the inhibitor of protein phosphatase 2A (PP2A), okadaic acid inhibited VCA-induced dephosphorylation of Akt and inhibition of telomerase activity. Taken together, VCA induces apoptotic cell death through Akt signaling pathway in correlated with the inhibition of telomerase activity and the activation of caspase-3. From these results, together with our previous studies, we suggest that VCA triggers molecular changes that resulting in the inhibition of cell growth and the induction of apoptotic cell death of cancer cells, which suggest that VCA may be useful as chemotherapeutic agent for cancer cells.