• Title/Summary/Keyword: p38 kinase

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Induction of Selective Cell Death of Oral Squamous Carcinoma Cells by Integrin α2 Antibody and EGFR Antibody (인테그린 α2와 상피성장인자수용체 차단항체의 저해작용을 통한 구강편평상피암 세포의 선택적 제거)

  • Choi, Yeon-Sik;Kim, Gyoo-Cheon;Yoon, Sik;Hwang, Dae-Seok;Kim, Cheol-Hun;Jeon, Young-Chan;Byun, June-Ho;Shin, Sang-Hun;Kim, Uk-Kyu
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.35 no.3
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    • pp.143-154
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    • 2013
  • Purpose: This study was to find efficacy of integrin alpha2 (${\alpha}_2$) and epidermal growth factor receptor (EGFR) as tumor marker of oral squamous cell carcinoma (SCC) and clarify the selective cell death effect of anti-integrin ${\alpha}_2$ and anti-EGFR on SCC cells, additionally testify conjugated gold nanoparticles (GNP) with air plasma for selective cell death of oral SCC. Methods: Expression of integrin ${\alpha}_2$, EGFR on human SCC cells (SCC25) were examined by western blot. SCC25 cells were treated with anti-integrin ${\alpha}_2$, anti-EGFR and analysed by Hemacolor staining, immunoflorescence staining, FACS flow cytometry. Conjugated GNP with integrin ${\alpha}_2$, EGFR antibody were treated by air plasma on SCC cells. Results: Integrin ${\alpha}_2$ and EGFR were over-expressed on SCC25 cells than normal lung WI-38 cells. The cell viability rate of SCC25 cells treated with anti-integrin ${\alpha}_2$, anti-EGFR was lower than WI-38 cells. The concentration changes of nucleus, releasing cytochrome c and apoptosis inducing factor (AIF) from mitochondria to cytosol were observed. The changes of proteins related with apoptosis were observed. Increase of bax, bcl-xL, activation of caspase-3, -7, -9, and fragmentation of PARP, DFF45 and decrease of lamin A/C in SCC25 cells were observed. In FACS, increase of sub-$G_1$ and S phase was observed. Cell cycle related proteins, Such as cyclin D1, cyclin dependent kinase (CDK) 4, cyclin A, cyclin E, CDK 2, p27 were decreased. After SCC25 cells treated with conjugatged GNP-Integrin ${\alpha}_2$, GNP-EGFR, additionally air plasma, the cell death rate was significantly increased. Conclusion: Integrin ${\alpha}_2$, EGFR were over-expressed in oral SCC cells. Anti-integrin ${\alpha}_2$, anti-EGFR in SCC25 cells induced apoptosis selectively. When GNP-anti integrin ${\alpha}_2$, GNP-anti EGFR were treated with air plasma on SCC25 cells, cancer cells were died more selectively. GNP-anti integrin ${\alpha}_2$, GNP-anti EGFR with air plasma could be treatment choice of oral SCC.

Effects of Curcumae longae Rhizoma and Cinnamomi Ramulus Mixture on Anti-inflammatory Activities in Lipopolysaccharide-stimulated RAW 264.7 Cells (강황(薑黃) 계지(桂枝) 복합물이 RAW 264.7 세포에서 항염증 활성에 미치는 영향)

  • Ji, Choi;Hae-Jin, Park;Il-ha, Jeong;Min Ju, Kim;Mi-Rae, Shin;Seong-Soo, Roh;Soon-Ae, Park;Mi-Lim, Kim
    • The Korea Journal of Herbology
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    • v.38 no.2
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    • pp.17-26
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    • 2023
  • Objectives : A persistent inflammatory response can cause diseases such as fibrosis, cancer, and allergies. This study aimed to investigate the anti-inflammatory activity of Curcumae longae Rhizoma and Cinnamomi Ramulus Mixture (CCM) in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Methods : The total polyphenol and flavonoid contents of CCM were confirmed through an in vitro experiment. Also, radical scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and Hydroxyl were confirmed. Moreover, ferric reducing antioxidant power (FRAP) activity were confirmed. After, CCM (50, 100, and 200 ㎍/mL) were applied to 0.1 ㎍/mL LPS-stimulated RAW264.7 cells. The levels of nitric oxide (NO) and pro-inflammatory cytokines in the supernatant fraction were determined. Also, the expressions of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways were detected using Western blot. Results : As a result of in vitro experiments, there was an excellent antioxidant activity in CCM-treated cells. In addition, in RAW264.7 cells stimulated with LPS, the increased NO level was inhibited in a concentration-dependent manner by the treatment of CCM. In addition, inflammatory cytokines production were significantly inhibited in a concentration-dependent manner in CCM-treated group. CCM treatment significantly decreased the protein expressions of MAPKs. Moreover, the expressions of NF-κBp65 and cyclooxygenase-2 (COX-2) were significantly decreased when 200 mg/kg of CCM was applied, and phospho-inhibitor of nuclear factor kappa B-α (p-IκBα) and inducible nitric oxide synthase (iNOS) were significantly decreased at all concentrations treated with CCM. Conclusion : Our findings show that CCM exhibited excellent antioxidant activity and exhibited superior anti-inflammatory effect through the MAPKs and NF-κB pathways in LPS-stimulated RAW 264.7 macrophages.

Inhibitory Effects of Tenebrio molitor Larvae Ethanol Extract on RANKL-Induced Osteoclast Differentiation (갈색거저리 유충 에탄올 추출물이 RANKL에 의해 유도되는 파골세포 분화에 미치는 영향)

  • Seo, Minchul;Baek, Minhee;Lee, Hwa Jeong;Shin, Yong Pyo;Lee, Joon Ha;Kim, In-Woo;Kim, Mi-Ae;Hwang, Jae-Sam
    • Journal of Life Science
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    • v.30 no.11
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    • pp.983-989
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    • 2020
  • The balance between bone-resorbing osteoclasts and bone-forming osteoblasts is key to bone health. An imbalance between osteoclasts and osteoblasts leads to various bone-related disorders, such as osteoporosis, osteomalacia, and osteopetrosis. However, the bone-resorption inhibitor drugs that are currently used may cause side effects. Natural substances have recently received much attention as therapeutic drugs for the treatment of bone health. This study was designed to determine the effect of Tenebrio molitor larvae ethanol extract (TME) on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. To measure the effect of TME on osteoclast differentiation, RAW264.7 cells were treated with RANKL with or without TME for 5 days. The tartrate-resistant acid phosphatase (TRAP) activity was significantly inhibited by treatment of TME without cytotoxicity up to 2 mg/ml. In addition, TME effectively suppressed expression of osteoclast differentiation-related marker genes and proteins such as TRAP, NFATc1, and c-Src. TME also significantly inhibited the p38 mitogen-activated protein kinase (MAPK) signaling pathway without affecting ERK and JNK signaling in RANKL-induced RAW264.7 cells. Consequently, we conclude that TME suppresses osteoclast differentiation by inhibiting RANKL-induced osteoclastogenic genes expression through the p38 MAPK signaling pathways. These results suggest that TME and its bioactive components are potential therapeutics for bone-related diseases such as osteoporosis.

Destabilization of TNF-α mRNA by Rapamycin

  • Park, Jong-Woo;Jeon, Ye-Ji;Lee, Jae-Cheol;Ahn, So-Ra;Ha, Shin-Won;Bang, So-Young;Park, Eun-Kyung;Yi, Sang-Ah;Lee, Min-Gyu;Han, Jeung-Whan
    • Biomolecules & Therapeutics
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    • v.20 no.1
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    • pp.43-49
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    • 2012
  • Stimulation of mast cells through the high affinity IgE receptor (Fc${\varepsilon}$RI) induces degranulation, lipid mediator release, and cytokine secretion leading to allergic reactions. Although various signaling pathways have been characterized to be involved in the Fc${\varepsilon}$RI-mediated responses, little is known about the precious mechanism for the expression of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) in mast cells. Here, we report that rapamycin, a specific inhibitor of mammalian target of rapamycin (mTOR), reduces the expression of TNF-${\alpha}$ in rat basophilic leukemia (RBL-2H3) cells. IgE or specific antigen stimulation of RBL-2H3 cells increases the expression of TNF-${\alpha}$ and activates various signaling molecules including S6K1, Akt and p38 MAPK. Rapamycin specifically inhibits antigeninduced TNF-${\alpha}$ mRNA level, while other kinase inhibitors have no effect on TNF-${\alpha}$ mRNA level. These data indicate that mTOR signaling pathway is the main regulation mechanism for antigen-induced TNF-${\alpha}$ expression. TNF-${\alpha}$ mRNA stability analysis using reporter construct containing TNF-${\alpha}$ adenylate/uridylate-rich elements (AREs) shows that rapamycin destabilizes TNF-${\alpha}$ mRNA via regulating the AU-rich element of TNF-${\alpha}$ mRNA. The antigen-induced activation of S6K1 is inhibited by specific kinase inhibitors including mTOR, PI3K, PKC and $Ca^{2+}$chelator inhibitor, while TNF-${\alpha}$ mRNA level is reduced only by rapamycin treatment. These data suggest that the effects of rapamycin on the expression of TNF-${\alpha}$ mRNA are not mediated by S6K1 but regulated by mTOR. Taken together, our results reveal that mTOR signaling pathway is a novel regulation mechanism for antigen-induced TNF-${\alpha}$ expression in RBL-2H3 cells.

The Effect of Aralia Cordata Thunb and Cimicifuga Heracleifolia on Cartilage Protection by the Regulation of Metabolism in Human Osteoarthric Chondrocytes (퇴행성 관절염에 대한 독활.승마 복합처방의 대사조절을 통한 연골보호 효과)

  • Shin, Ye-Ji;Beak, Yong-Hyeon;Park, Dong-Suk;Kim, Jae-Kyu;Koh, Hyung-Kyun
    • Journal of Acupuncture Research
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    • v.27 no.4
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    • pp.39-53
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    • 2010
  • 목적 : 퇴행성 관절염은 염증성 사이토카인인 IL-$1\beta$에 의해 연골관절이 파괴되고 이로 인해 염증성 사이토카인이 더욱 증가하는 질환이다. 퇴행성 관절염을 치료하기 위해서는 연골 파괴를 가속화시키는 catabolic cytokines의 활성을 줄이고, 성장인자인 anabolic factor의 활성을 증가시는 연골 보호 작용이 있어야 한다. 본 연구에서는 독활 승마 처방(OAH19T)이 catabolic/anabolic 대사 조절에 어떤 영향을 미치는지와 그 신호 전달 기전에 대해 연구하였다. 또한 OAH19T를 구성하는 단미재 및 임상에서 사용되는 COX-2 inhibitor인 Celebrex(CEL)와 효능을 비교 실험하였다. 방법 : 배양된 세포에 IL-$1\beta$로 자극한 후 (1) glycosaminoglycan(GAG)의 분해 억제 정도, (2) OAH19T와 CEL에 대하여 MMP-1과 MMP-3의 유전자 발현 및 활성 억제, (3) Aggrecan 및 Aggrecanases의 유전자 발현 및 활성 억제, (4) OAH19T의 growth factor의 조절 능력, (5) MAPK pathway 등을 RT-PCR(reverse transcriptase-polymerase chain reaction), ELISA(Enzyme-linked immunosorbent assay), western blot, viability 측정을 통해 검증했다. 결과 : 사람 관절 세포에서 (1) 독활 승마 각각의 단미재, 임상에서 사용중인 셀레콕시브(CEL), 조인스보다 실험 약물(OAH19T)이 저농도에서 GAG 분해 억제 효과가 우수하였고, 부탄올로 분획한 OAH19B와는 동등한 효과를 보였다. (2) OAH19T는 IL-$1\beta$에 의하여 활성화된 MMP-1과 MMP-3의 발현을 모두 억제하였으나, CEL은 MMP-1의 발현은 억제하였으나 MMP-3의 발현은 억제하지 못하였다. (3) OAH19T는 IL-$1\beta$에 의하여 손상된 Aggrecan을 회복시켰으며 이는 활성화된 Aggrecanase-1과 Aggrecanase-2를 억제시킴으로써 나타난 결과이다. 그러나 CEL의 경우, 손상된 Aggrecan을 회복시키지 못하였다. (4) 배양된 세포는 IL-$1\beta$에 의하여 TGF-$\beta$II및 TGF-$\beta$ receptor II의 발현이 억제되었으나, OAH19T는 TGF-$\beta$II및 TGF-$\beta$ receptor II의 발현을 회복시켜 OAH19T가 anabolic한 조절능력이 있음을 시사한다. 그러나 CEL의 경우 growth factor에 대한 조절 능력이 없었다. (5) 대사 조절 작용에 대한 기전으로서 MAPK pathway에 대해서 연구한 결과 IL-$1\beta$에 의하여 유도된 pERK, pp38 kinase의 활성은 억제하였고, pJNK의 활성은 변하지 않았다. 또한 OAH19T는 연골 세포에 독성이 없었으며 IL-$1\beta$에 의해 유도된 세포 증식만을 억제시켰다. 이 결과로, OAH19T가 OA chondrocyte의 탈분화 및 세포 고사를 억제하여 연골보호 및 회복 효과가 있음을 알 수 있었다. 결론 : OAH19T는 이를 구성하는 단미재 및 CEL보다 연골보호 효과가 월등하였고, 이러한 연골보호 효과는 catabolic cytokines/growth factors의 균형으로 대사조절을 통해 연골세포의 탈분화 및 세포 고사를 억제하여 연골보호 및 회복 효과가 있음을 알 수 있었다.

Attenuation of Reperfusion Injury with Angiotension $AT_1$ Receptor Blockade in Rat Myocardial Ischemic Model (백서 심근 허혈 모델에서 angiotension $AT_1$수용체 차단제의 재관류 손상 감소 효과)

  • Choi, Jun-Young;Choi, Dong-Ju;Ahn, Hyuk
    • Journal of Chest Surgery
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    • v.34 no.3
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    • pp.203-211
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    • 2001
  • 배경: AT$_1$수용체의 길항제가 세포 수준에서 심근을 재관류 손사으로부터 보호할수 있다는 것으로 알려져 있지만, 생체내에서의 효과나 그 기전은 아직 명확히 밝혀지지 않았다. 본 연구에서는 백서 심근 허혈 모델을 이용하여, AT$_1$ 수용체의 길항제들 중 하나인 irbesartan이 심근이 재관휴 손상에 미치는 효과를 알아보고, 재관류 손상을 매개하는 한 각지 기전으로서 세포자멸의 기여에 대하여 연구하고자 하였다. 대상 및 방법: Sprague-Dawley 백서에서 무작용 부형약(10% gum arabic: 1군, 개체수=14관) irbesartan(50mg/kg/day :II 군, 개체수=12)을 각각 3일 동안 24시간마다 경구로 투여하였다. 실험동물의 좌 관상 동맥을 45분간 결찰하였다가, 그 후 2시간 동안 재관류시킨 다음 심장을 적출 하였다. TTC(triphenyltetrazolium chloride) 염색법을 이용하여, 허혈 노출 부위에 대한 심근 경색 부위의 비율을 측정하였다. Agarose gel 전기영동상의 DNa 분절 양상과 TUNEL(TdT-mediated dUCP nick end labeling) 염색을 관찰하여 세포자멸이 일어난 정도를 평가하였다. 세포자멸을 조절하는데 관여하는 것으로 알려진 Bcl-2(B-cell lymphoma 2 gene), Bad 등의 단백과 ERK (extracellular signal-regulated kinase), p-38 등 신호전달체계에 작용하는 MAPKs(mitogen-activated protein kinases)의 발현을 측정하기 위하여 Western blot을 시행하였다. 결과: 허혈 노출부위에 대한 심근 경색부위의 비율은 II군(42$\pm$2.7%)이 I군( 64.1$\pm$4.65)에 비해 유의하게 작았다.(p< 0.05), Agarose gel 전기영동상의 DNA laddering 양상은 I군에서 보다 높게 발현되었다. Bad와 ERK2의 발현은 두 군간에 유의한 차이가 없었다. 결론: AT$_1$수용체 길항제인 irbesartan은 생체에서 심근의 재관류 손상을 줄이는 효과가 있었다. 이 효과는 적어도 부분적으로 나만 심근세포의 세포자멸이 감소한 것에 기인한 것으로 설명할 수 있으며, 이 항-세포 자멸 효과는 Bcl-2의 발현증가와 관련이 있는 것으로 추정되었다.

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Change of Extracellular Matrix of Human Vocal Fold Fibroblasts by Vibratory Stimulation (진동이 성대세포주의 세포외기질 변화에 대한 연구)

  • Kim, Ji Min;Shin, Sung-Chan;Kwon, Hyun-Keun;Cheon, Yong-Il;Ro, Jung Hoon;Lee, Byung-Joo
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.32 no.1
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    • pp.15-23
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    • 2021
  • Background and Objectives During speech, the vocal folds oscillate at frequencies ranging from 100-200 Hz with amplitudes of a few millimeters. Mechanical stimulation is an essential factor which affects metabolism of human vocal folds. The effect of mechanical vibration on the cellular response in the human vocal fold fibroblasts cells (hVFFs) was evaluated. Materials and Method We created a culture systemic device capable of generating vibratory stimulations at human phonation frequencies. To establish optimal cell culture condition, cellular proliferation and viability assay was examined. Quantitative real time polymerase chain reaction was used to assess extracellular matrix (ECM) related and growth factors expression on response to changes in vibratory frequency and amplitude. Western blot was used to investigate ECM and inflammation-related transcription factor activation and its related cellular signaling transduction pathway. Results The cell viability was stable with vibratory stimulation within 24 h. A statistically significant increase of ECM genes (collagen type I alpha 1 and collagen type I alpha 2) and growth factor [transforming growth factor β1 (TGF-β1) and fibroblast growth factor 1 (FGF-1)] observe under the experimental conditions. Vibratory stimulation induced transcriptional activation of NF-κB by phosphorylation of p65 subunit through cellular Mitogen-activated protein kinases activation by extracellular signal regulated kinase and p38 mitogen-activated protein kinases (MAPKs) phosphorylation on hVFFs. Conclusion This study confirmed enhancing synthesis of collagen, TGF-β1 and FGF was testified by vibratory stimulation on hVFFs. This mechanism is thought to be due to the activation of NF-κB and MAPKs. Taken together, these results demonstrate that vibratory bioreactor may be a suitable alternative to hVFFs for studying vocal folds cellular response to vibratory vocalization.

Pretreatment Neutrophil-to-Lymphocyte Ratio and Smoking History as Prognostic Factors in Advanced Non-Small Cell Lung Cancer Patients Treated with Osimertinib

  • Park, Ji Young;Jang, Seung Hun;Lee, Chang Youl;Kim, Taehee;Chung, Soo Jie;Lee, Ye Jin;Kim, Hwan Il;Kim, Joo-Hee;Park, Sunghoon;Hwang, Yong Il;Jung, Ki-Suck
    • Tuberculosis and Respiratory Diseases
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    • v.85 no.2
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    • pp.155-164
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    • 2022
  • Background: The remarkable efficacy of osimertinib in non-small cell lung cancer (NSCLC) with acquired T790M mutation has been widely documented in clinical trials and real-world practice. However, some patients show primary resistance to this drug. Even patients who initially show a favorable response have inconsistent clinical outcomes later. Therefore, the aim of this study was to identify additional clinical predictive factors for osimertinib efficacy. Methods: A prospective cohort of patients with acquired T790M positive stage IV lung adenocarcinoma treated with osimertinib salvage therapy in Hallym University Medical Center were analyzed. Results: Sixty-one eligible patients were analyzed, including 38 (62%) women and 39 (64%) who never smoked. Their mean age was 63.3 years. The median follow-up after treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) was 36.0 months (interquartile range, 24.7-50.2 months). The majority (n=45, 74%) of patients were deceased. Based on univariate analysis, low baseline neutrophil-to-lymphocyte ratios (NLR), age ≥50 years, never-smoking history, stage IVA at osimertinib initiation, and prolonged response to previous TKIs (≥10 months) were associated with a significantly longer progression-free survival (PFS). Multivariate analysis showed that never-smoking status (hazard ratio [HR], 0.54; 95% confidence interval [CI], 0.30-0.98; p=0.041) and a baseline NLR less than or equal to 3.5 (HR, 0.23; 95% CI, 0.12-0.45; p<0.001) were independently associated with a prolonged PFS with osimertinib. Conclusion: Smoking history and high NLR were independent negative predictors of osimertinib PFS in patients with advanced NSCLC developing EGFR T790M resistance after the initial EGFR-TKI treatment.

Anti-inflammatory Effect of Heat-Killed Enterococcus faecalis, EF-2001 (열처리 사균체 엔테로코커스 패칼리스 EF-2001의 항염증 효과)

  • Choi, Moon-Suk;Chang, Sang-Jin;Chae, Yuri;Lee, Myung-Hun;Kim, Wan-Joong;Iwasa, Masahiro;Han, Kwon-Il;Kim, Wan-Jae;Kim, Tack-Joong
    • Journal of Life Science
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    • v.28 no.11
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    • pp.1361-1368
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    • 2018
  • Inflammation is the most common condition in the human body. Tissue damage triggers inflammation, together with vasodilation and increased blood flow at the inflamed site, resulting in edema. Inflammatory responses are also triggered by lipopolysaccharide (LPS), a Toll-like receptor Enterococcus faecalis, a gram-positive organism, has been reported to possess immunomodulatory and preventive activities; however, its use may present risks of sepsis and other systemic infections. Heat-killed Enterococcus faecalis (EF-2001) has been reported to induce antitumor activity, but its effects on inflammation are not known. In the present study, we investigated the effect of EF-2001 on LPS-induced macrophage inflammatory responses. EF-2001 treatment reduced nitric oxide (NO) production, indicating suppression of inflammatory reactions. EF-2001 showed no cytotoxicity in macrophages. Further investigation of the anti-inflammatory mechanism of EF-2001 indicated that EF-2001 reduced the LPS-induced expression of inducible nitric oxide synthase and cyclooxygenase-2. EF-2001 also reduced f the LPS induction of several inflammatory molecules involved in the nuclear factor-${\kappa}B$ ($NF-{\kappa}B$) and mitogen-activated protein kinase pathways, including ERK, JNK, and p38 phosphorylation, in a concentration-dependent manner. Additionally, EF-2001 inhibited Akt phosphorylation and increased the expression of the inhibitory ${\kappa}B$ ($I{\kappa}B$) protein, an inhibitor of $NF-{\kappa}B$. EF-2001 also inhibited the nuclear translocation of p65. These results suggest that EF-2001 has anti-inflammatory properties and may be useful for treating inflammatory diseases.

Immunohistochemical Study of Phosphatase and Tensin Homolog Deleted on Chromosome Ten in Gefitinib Treated Nonsmall Cell Lung Cancer Patients (폐암 조직에서의 PTEN 발현 정도와 Gefitinib의 반응율과의 관계)

  • Lee, Sung Yong;Lee, Ju Han;Jung, Jin Yong;Lee, Kyoung Ju;Lee, Seung Hyeun;Kim, Se Joong;Lee, Eun Joo;Hur, Gyu Young;Jung, Ki Hwan;Jung, Hye Cheol;Lee, Sang Yeub;Kim, Je Hyeong;Shin, Chol;Shim, Jae Jeong;In, Kwang Ho;Kang, Kyung Ho;Yoo, Se Hwa
    • Tuberculosis and Respiratory Diseases
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    • v.58 no.5
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    • pp.473-479
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    • 2005
  • Background : Gefitinib targets the epidermal growth factor receptor r(EGFR), and Gefitinib has antitumor activity in patient with non-small cell lung cancer (NSCLC). However, only 10 to 20 percent of patients show a clinical response to this drug, and the molecular mechanisms underlying patient sensitivity to gefitinib are unknown. PTEN (Phosphatase and tensin homolog deleted on chromosome Ten) plays a role for the modulation of the phosphatidylinositol 3-kinase pathway (PI3K), which is involved in cell proliferation and survival, so that it can inhibit cell cycle progression and induce G1 arrest. Therefore, we analyzed the relationship between PTEN expression and gefitinib's responsiveness in patients having advanced non small cell lung cancer that had progressed after previous chemotherapy. Methods : The expression of PTEN was studied by immunohistochemistry in paraffin-embedded tumor blocks that were obtained from 22 patients who had been treated with gefitinib from JAN, 2001 to AUG. 2004. For the evaluation of the relationships between the PTEN expression, the clinical stage and the basal characteristics, those cases that showed the respective antigen expression in >50% of the tumor cells were considered positive. Results : The positive rate of PTEN staining was 55% of the total of 22 patients. There was a significant relationship between the increased expression of PTEN and the response group (p=0.039). However, there was no significant relationship between the expression of PTEN and other clinicopathologic characteristics. Conclusion: The expression of PTEN in patients with advanced non small cell lung cancer that has progressed after previous chemotherapy may play a role in gefitinib's responsiveness.