• Biomolecules & Therapeutics
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• 제31권4호
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• pp.456-465
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• 2023

Cervical tumors represent a prevalent form of cancer affecting women worldwide; current treatment options involve surgery, radiotherapy, and chemotherapy. Angiogenesis, the process of new blood vessel formation, is a crucial factor in cervical tumor growth. The molecular mechanisms underlying the effects of the liver kinase B1 (LKB1/STK11) tumor suppressor protein on tumor angiogenesis have not been elucidated. Therefore, we investigated the role of LKB1 in cervical tumor angiogenesis both in vitro and in vivo in this study. Our results demonstrated that LKB1 inhibited cervical tumor angiogenesis by suppressing the expression of angiogenesis-related factors such as vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1α. LKB1 directly affected both carcinoma and vascular endothelial cells, resulting in a significant reduction in tumor growth and angiogenesis. Furthermore, LKB1 was found to bind to VEGF receptor 2 (VEGFR-2) and target the VEGFR-2-mediated protein kinase B/mechanistic target of rapamycin signaling pathway in endothelial cells, thereby reducing cervical tumor growth and angiogenesis. Our study provides new insights into the molecular mechanisms underlying the anti-tumor and anti-angiogenic effects of LKB1 in cervical cancer. These findings will help develop new therapeutic strategies for cervical cancer.

• Biomolecules & Therapeutics
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• 제31권3호
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• pp.330-339
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• 2023

Liver kinase B1 (LKB1) is a crucial tumor suppressor involved in various cellular processes, including embryonic development, tumor initiation and progression, cell adhesion, apoptosis, and metabolism. However, the precise mechanisms underlying its functions remain elusive. In this study, we demonstrate that LKB1 interacts directly with malic enzyme 3 (ME3) through the N-terminus of the enzyme and identified the binding regions necessary for this interaction. The binding activity was confirmed to promote the expression of ME3 in an LKB1-dependent manner and was also shown to induce apoptosis activity. Furthermore, LKB1 and ME3 overexpression upregulated the expression of tumour suppressor proteins (p53 and p21) and downregulated the expression of antiapoptotic proteins (nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and B-cell lymphoma 2 (Bcl-2)). Additionally, LKB1 and ME3 enhanced the transcription of p21 and p53 and inhibited the transcription of NF-κB. Moreover, LKB1 and ME3 suppressed the phosphorylation of various components of the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B signaling pathway. Overall, these results suggest that LKB1 promotes pro-apoptotic activities by inducing ME3 expression.

• Tuberculosis and Respiratory Diseases
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• 제64권5호
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• pp.362-368
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• 2008

연구배경: LKB1 (STK11)유전자는 Peutz-Jeghers syndrome에서 생식세포 돌연변이가 있으면 소화기와 폐를 포함한 타 장기의 암 발생 위험도가 증가한다고 알려져 있으며, 또한 종양 억제 기능이 있다고도 알려지고 있다. 하지만 현재까지 폐암에서 LKB1 유전자의 생물학적 기능이 명확하게 밝혀져 있지 않아, 저자들은 폐암조직에서 LKB1 단백질 발현소실과 임상양상 및 조직병리와의 연관관계를 알아보고자 하였다. 방법: 1998년 3월부터 2006년 3월까지 본원에 내원하여 원발성 폐암으로 진단받고 근치적 절제술을 시행 받은 77명의 환자를 대상으로 하였다. 파라핀에 포매된 조직을 택하여 면역조직화학염색법으로 LKB1 단백질 발현을 확인하였고, 정상 기관지 상피세포 세포질에서의 단백질 발현과 비슷한 정도의 발색을 갖는 종양세포가 전체 종양에서 30% 이상인 경우를 양성으로 판정하였다. 결과: LKB1 발현 양성은 40% (31/77)였고, 남성, 흡연, 편평상피암인 경우에 LKB1 발현 음성률이 통계적으로 유의하게 높았다. 종양위치가 중앙부위일수록 LKB1 발현 음성률이 증가하는 경향이 있으며, 종양 위치가 말초 부위인 경우 흡연력이 있는 군에서 LKB1 발현 음성률이 통계적으로 유의하게 높았다. TNM 병기가 진행할수록 LKB1 발현 음성률이 증가하는 경향이 있었으며, T2 병기 이상, N 병기가 진행할수록 LKB1 발현 음성률이 높아지는 경향이 있었으나, 통계적 유의성은 보이지 않았다. 결론: 원발성 폐암환자에서 LKB1 발현소실은 성별, 흡연력, 조직병리 형태와 의미있는 상관관계를 보였으나, 예후인자로서의 의의는 찾지 못했다. 하지만 환자의 숫자가 적어 추후의 연구가 이루어져야 할 것으로 사료된다.

• Nutrition Research and Practice
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• 제14권4호
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• pp.309-321
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• 2020

BACKGROUND/OBJECTIVES: The present study aimed to evaluate the effects of folic acid supplementation in high-fructose-induced hepatic steatosis and clarify the underlying mechanism of folic acid supplementation. MATERIALS/METHODS: Male SD rats were fed control, 64% high-fructose diet, or 64% high-fructose diet with folic acid for eight weeks. Plasma glutamate-pyruvate transaminase, glutamate-oxaloacetate transaminase, lipid profiles, hepatic lipid content, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: The HF diet significantly increased hepatic total lipid and triglyceride (TG) and decreased hepatic SAM, SAH, and SAM:SAH ratio. In rats fed a high fructose diet, folic acid supplementation significantly reduced hepatic TG, increased hepatic SAM, and alleviated hepatic steatosis. Moreover, folic acid supplementation in rats fed high fructose enhanced the levels of phosphorylated AMP-activated protein kinase (AMPK) and liver kinase B (LKB1) and inhibited phosphorylation of acetyl coenzyme A carboxylase (ACC) in the liver. CONCLUSIONS: These results suggest that the protective effect of folic acid supplementation in rats fed high fructose may include the activation of LKB1/AMPK/ACC and increased SAM in the liver, which inhibit hepatic lipogenesis, thus ameliorating hepatic steatosis. The present study may provide evidence for the beneficial effects of folic acid supplementation in the treatment of non-alcoholic fatty liver disease.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.43-43
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• 2023

In this study, we investigated in vitro inhibitory activity of wild-simulated ginseng (WSG) against non-alcoholic fatty liver disease using HepG-2 cells. T0901317 treatment increased the lipid accumulation in HepG-2 cells, but WSG treatment inhibited T0901317-mediated lipid accumulation. In addition, WSG downregulated T0901317-mediated expression of SREBP-1c, ACC, FAS and SCD-1 protein. In addition, WSG increased the phosphorylation level of LKB1 and AMPK. Compound C treatment blocked WSG-mediated downregulation of SREBP-1c protein. In conclusion, WSG is considered to inhibit the accumulation of lipids and triglycerides in HepG-2 cells by inducing the activation of LKB1 and AMPK successively, thereby reducing the expression of FAS, ACC, and SCD-1 through suppression of SREBP-1c expression.

• Journal of Yeungnam Medical Science
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• 제29권2호
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• pp.77-82
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• 2012

AMP-activated protein kinase (AMPK) is an important cellular fuel sensor. Its activation requires phosphorylation at Thr-172, which resides in the activation loop of the ${\alpha}1$ and ${\alpha}2$ subunits. Several AMPK upstream kinases are capable of phosphorylating AMPK at Thr-172, including LKB1 and CaMKK${\beta}$ ($Ca^{2+}$/calmodulin-dependent protein kinase kinase${\beta}$). AMPK has been implicated in the regulation of physiological signals, such as in the inhibition of cholesterol fatty acid, and protein synthesis, and enhancement of glucose uptake and blood flow. AMPK activation also exhibits several salutary effects on the vascular function and improves vascular abnormalities. AMPK is modulated by numerous hormones and cytokines that regulate the energy balance in the whole body. These hormone and cytokines include leptin, adiponectin, ghrelin, and even thyroid hormones. Moreover, AMPK is activated by several drugs and xenobiotics. Some of these are in being clinically used to treat type 2 diabetes (e.g., metformin and thiazolidinediones), hypertension (e.g., nifedipine and losartan), and impaired blood flow (e.g., aspirin, statins, and cilostazol). I reviewed the precise mechanisms of the AMPK activation pathway and AMPK-modulating drugs.

• 대한본초학회지
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• 제36권6호
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• pp.39-46
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• 2021

Objectives : AMP-activated protein kinase (AMPK) is a key metabolic regulator that reduces lipogenesis. AMPK is mainly activated via phosphorylation of liver kinase B (LKB) 1 under energy stress. Here, we highlighted the anti-obesity effect and underlying mechanism of Coix lacryma-jobi var. mayuen Stapf sprout water extract (CSW) sprout extract in connection with the LKB1/AMPK signaling pathway. Methods : C57BL/6 mice (20~25 g) fed HFD to induce obesity and at the same time administered CSW 100 mg/kg (CSWL; (CSWL; CSW low concentration) or CSW 200 mg/kg (CSWH; CSW high concentration) or Garcinia extract (Garcinia) 200 mg/kg orally for 6 weeks. Body weight and food intake were measured at the same time each day. After 6 weeks of CSW administration, liver tissue and serum were obtained through an autopsy. After the end of the experiment, biochemical analysis (triglycerides (TG), total cholesterol (TC), HDL-cholesterol, and LDL-cholesterol) was performed on the serum. And then, protein levels related to TG and TC synthesis were measured through western blot analysis in liver tissue. Results : As a result, serum TG, TC, and LDL-cholesterol levels were significantly increased in the control group and significantly decreased in the CSW administration group. On the other hand, the HDL-cholesterol level was increased in the CSW-administered group. And as a result of Western blot analysis, CSW significantly increased the phosphorylation of LKB1 & AMPK, and remarkably decreased the expression of factors related to TG and TC synthesis. Conclusions : Our findings suggest that CSW influences the TG and TC synthesis to positively affect HFD-induced obesity in C57BL/6 mice.

• 한국자원식물학회지
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• 제36권1호
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• pp.26-31
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• 2023

간세포 내 LXRα활성화는 전사조절인자인 SREBP-1c의 발현을 증가시키고, 발현된 SREBP-1c는 핵내로 이동하여 지질형성 관련 유전자인 FAS, ACC, SCD-1 등의 프로모토에 결합하여 FAS, ACC, SCD-1을 유도하여 중성지질의 합성을 활성화시켜 비알코올성 지방간을 초래한다. 그러나 산양삼은 LKB1 그리고 연속적으로 AMPK의 활성화을 유도하여 SREBP-1c의 발현 억제를 통해 FAS, ACC, SCD-1의 발현을 감소시켜 간세포 내 지질 및 중성지질의 축적을 억제하는 것으로 판단된다. 본 결과를 미루어 볼 때, 산양삼은 비알코올성 지방간을 예방하기 위한 건강기능성 식품소재로 개발로 활용될 수 있을 것으로 판단된다.

• Journal of Ginseng Research
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• 제41권3호
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• pp.392-402
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• 2017

Background: Previously, we reported that Korean Red Ginseng inhibited liver fibrosis in mice and reduced the expressions of fibrogenic genes in hepatic stellate cells (HSCs). The present study was undertaken to identify the major ginsenoside responsible for reducing the numbers of HSCs and the underlying mechanism involved. Methods: Using LX-2 cells (a human immortalized HSC line) and primary activated HSCs, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assays were conducted to examine the cytotoxic effects of ginsenosides. $H_2O_2$ productions, glutathione contents, lactate dehydrogenase activities, mitochondrial membrane permeabilities, apoptotic cell subpopulations, caspase-3/-7 activities, transferase dUTP nick end labeling (TUNEL) staining, and immunoblot analysis were performed to elucidate the molecular mechanism responsible for ginsenoside-mediated cytotoxicity. Involvement of the AMP-activated protein kinase (AMPK)-related signaling pathway was examined using a chemical inhibitor and small interfering RNA (siRNA) transfection. Results and conclusion: Of the 11 ginsenosides tested, 20S-protopanaxadiol (PPD) showed the most potent cytotoxic activity in both LX-2 cells and primary activated HSCs. Oxidative stress-mediated apoptosis induced by 20S-PPD was blocked by N-acetyl-$\text\tiny L$-cysteine pretreatment. In addition, 20S-PPD concentration-dependently increased the phosphorylation of AMPK, and compound C prevented 20S-PPD-induced cytotoxicity and mitochondrial dysfunction. Moreover, 20S-PPD increased the phosphorylation of liver kinase B1 (LKB1), an upstream kinase of AMPK. Likewise, transfection of LX-2 cells with LKB1 siRNA reduced the cytotoxic effect of 20S-PPD. Thus, 20S-PPD appears to induce HSC apoptosis by activating LKB1-AMPK and to be a therapeutic candidate for the prevention or treatment of liver fibrosis.

• 대한한의학방제학회지
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• 제30권3호
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• pp.137-143
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• 2022

Objectives : Brain-Liver axis is an important target of the chronic human diseases. Hepatic steatosis is one of the most famous disorders in the chronic diseases. This study investigated the moderating effect of beneficial herbs on the fat accumulation, which is mediated by the LXR alpha-SREBP-1c signaling pathway. Methods : In order to confirm the SREBP-1c inhibitory effect, we performed immonoblotting ananlysis using HepG2 cells and Huh 7 cells treated by T0901317, the ligand of LXRα. Results : Forsythiae suspensa water extract (FSE) was not cytotoxicity in cell lines. FSE inhibited SREBP-1c protein expression in HepG2 and Huh7 cells induced by T0901317. In addition, FSE increased the phosphorylation of LKB1, which is associated with LXR-related pathway in HepG2 and Huh 7 cells. Conclusions : These results showed that FSE activated LKB1 to suppress SREBP-1c, which protects the cells against oxidative stress.