• 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.

• 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.

• 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.

• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1985-1988
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• 2013

Aim: To study any correlation of LKB1 expression with prognosis in hepatocellular carcinoma (HCC) cases. Methods: A total of 70 HCC patients and 20 primary intrahepatic stone patients in the first affiliated hospital of Wenzhou Medical College were enrolled in this study. LKB1 expression was detected by immunohistochemistry. Patients were followed-up and prognostic factors were evaluated. Result: LKB1 expression was decreased in the HCC samples. Loss of LKB1 expression in HCC was significantly related to histologic grade (P=0.010), vascular invasion (P=0.025) and TMN stage (P=0.011). Patients showing negative LKB1 expression had a significantly shorter disease-free and overall survival than those with positive expression (P = 0.001, P=0.000, respectively). Multivariate Cox regression analysis indicated that LKB1 expression level was an independent factor of survival (P = 0.033). Conclusion: HCC patients with decreased expression LKB1 have a poor prognosis. The loss of LKB1 expression is correlated with a lower survival rate.

• Biomolecules & Therapeutics
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• 제29권6호
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• pp.650-657
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• 2021

Metformin is an anti-diabetic drug and has anticancer effects on various cancers. Several studies have suggested that metformin reduces cell proliferation and stimulates cell-cycle arrest and apoptosis. However, the definitive molecular mechanism of metformin in the pathophysiological signaling in endometrial tumorigenesis and metastasis is not clearly understood. In this study, we examined the effects of metformin on the cell viability and apoptosis of human cervical HeLa and endometrial HEC-1-A and KLE cancer cells. Metformin suppressed cell growth in a dose-dependent manner and dramatically evoked apoptosis in HeLa cervical cancer cells, while apoptotic cell death and growth inhibition were not observed in endometrial (HEC-1-A, KLE) cell lines. Accordingly, the p27 and p21 promoter activities were enhanced while Bcl-2 and IL-6 activities were significantly reduced by metformin treatment. Metformin diminished the phosphorylation of mTOR, p70S6K and 4E-BP1 by accelerating adenosine monophosphate-activated kinase (AMPK) in HeLa cancer cells, but it did not affect other cell lines. To determine why the anti-proliferative effects are observed only in HeLa cells, we examined the expression level of liver kinase B1 (LKB1) since metformin and LKB1 share the same signalling system, and we found that the LKB1 gene is not expressed only in HeLa cancer cells. Consistently, the overexpression of LKB1 in HeLa cancer cells prevented metformin-triggered apoptosis while LKB1 knockdown significantly increased apoptosis in HEC-1-A and KLE cancer cells. Taken together, these findings indicate an underlying biological/physiological molecular function specifically for metformin-triggered apoptosis dependent on the presence of the LKB1 gene in tumorigenesis.

• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4033-4039
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• 2013

Links between cancer and metabolism have been suggested for a long time but compelling evidence for this hypothesis came from the recent molecular characterization of the LKB1/AMPK signaling pathway as a tumor suppressor axis. Besides the discovery of somatic mutations in the LKB1 gene in certain type of cancers, a critical emerging point was that the LKB1/AMPK axis remains generally functional and could be stimulated by pharmacological molecules such as metformin in cancer cells. In addition, AMPK plays a central role in the control of cell growth, proliferation and autophagy through the regulation of mTOR activity, which is consistently deregulated in cancer cells. Targeting of AMPK/mTOR is thus an attractive strategy in the development of therapeutic agents against non-small-cell lung cancer (NSCLC). In this review, the LKB1/AMPK/mTOR signaling pathway is described, highlighting its protective role, and opportunities for therapeutic intervention, and clinical trials in NSCLC.

• 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.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2003년도 학술대회 발표논문집
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• pp.79-99
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• 2003

한국어의 동사성 명사와 형용사성 명사는 경동사와 결합하여 문장의 서술어 역할을 하는데 이때에 명사는 보어 자질을 경동사에 전달하고 이렇게 결합한 후에 생성되는 서술어 복합체가 술어로 역할 한다. 이번 구문분석 시스템 연구에서는 LKB 시스템을 통해 한국어에서 체언과 결합하는 격조사의 처리와 용언과 결합하는 어미의 처리 및 동사/형용사성 명사가 경동사에 보어 자질을 전달하여 술어 복합체를 이루는 현상을 집중적으로 다룬다.

• 한국언어정보학회지:언어와정보
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• 제11권1호
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• pp.25-38
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• 2007

So-called multiple nominative constructions (MNCs) in Korean are quite theoretically as well as computationally puzzling. This paper shows that a grammar allowing the interaction of declarative constraints on types of signs - in particular, constructions (phrases and clauses)-can provide a robust and efficient way of encoding generalizations for two different MNCs. The feasibility of the grammar developed has been checked with its implementation into the LKB (Linguistic Knowledge Building) system.

• 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.