• 생명과학회지
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• 제22권10호
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• pp.1428-1433
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• 2012

장수 또는 노화에 관한 연구는 여러 가지 유전적 요인과 생리학적 및 환경 요인들의 복잡한 조합에 의해 결정되므로, 이와 관련된 연구는 매우 흥미로운 분야이나 또한 어려운 주제이다. 지난 수십 년 동안 장수 또는 노화에 관여하는 분자 메커니즘을 찾기 위하여 동물 모델을 사용한 유전학적 접근법으로, 특이적 유전자를 결손 시키는 연구는 귀중한 도구임이 입증되었다. 장수에 관한 첫 번째 연구는 꼬마선충의 돌연변이체에서 발견되었으며, 이 선충의 인슐린/인슐린유사 성장인자-1 회로가 장수에 관여함이 밝혀졌다. 인슐린유사 성장인자-1은 인슐린과 유사한 아미노산 서열을 가진 폴리펩타이드로, 세포의 정상적인 성장과 발달에 관여한다. 이 발견 이후 인슐린/인슐린유사 성장인자-1 회로에 관여하는 많은 인자들이 선충과 초파리 연구에서 장수에 관여함이 밝혀졌다. 또한 특이적 유전자를 결손 시킨 생쥐 모델을 이용한 연구에서도 인슐린/인슐린유사 성장인자-1 회로뿐 아니라 성장호르몬/인슐린유사 성장인자 회로도 장수에 관여함이 지난 수십 년 동안의 연구결과로 밝혀졌다. 간 조직 특이적으로 인슐린유사 성장인자-1 유전자를 결손 시킨 생쥐모델을 이용한 최근의 연구 결과에 의하면 인슐린유사 성장인자-1 자체도 장수에 관여함이 최초로 밝혀졌으며, 이는 인슐린유사 성장인자-1 회로가 무척추동물뿐 아니라 척추동물에서도 장수에 관여함을 명백하게 보여주는 결과이다. 장수를 조절하는 분자 메커니즘은 아직 완전하게 설명되지 않지만, 감소되어진 인슐린유사 성장인자-1의 신호가 장수와 노화의 조절에 중요한 역할을 하며, 인슐린유사 성장인자-1 회로에 관여하는 여러 가지 유전자들의 장수에서의 역할을 유전자 조작된 생쥐모델을 이용하여 집중적으로 검토하려 한다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.4937-4944
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• 2015

MicroRNAs (miRNAs) are emerging as critical regulators in carcinogenesis and tumor progression. Recently, miR-99a has been reported as a tumor suppressor gene in various human cancers, but its functions in the context of anaplastic thyroid cancer (ATC) remain unknown. In this study, we reported that miR-99a was commonly downregulated in ATC tissue specimens and cell lines with important functional consequences. Overexpression of miR-99a not only dramatically reduced ATC cell viability by inducing cell apoptosis and accumulation of cells at G1 phase, but also inhibited tumorigenicity in vivo. We then screened and identified a novel miR-99a target, mammalian target of rapamycin (mTOR), and it was further confirmed by luciferase assay. Up-regulation of miR-99a would markedly reduce the expression of mTOR and its downstream phosphorylated proteins (p-4E-BP1 and p-S6K1). Similar to restoring miR-99a expression, mTOR down-regulation suppressed cell viability and increased cell apoptosis, whereas restoration of mTOR expression significantly reversed the miR-99a antitumor activity and the inhibition of mTOR/p-4E-BP1/p-S6K1 signal pathway profile. In clinical specimens and cell lines, mTOR was commonly overexpressed and its protein levels were statistically inversely correlated with miR-99a expression. Taken together, our results demonstrated for the first time that miR-99a functions as a tumor suppressor and plays an important role in inhibiting the tumorigenesis through targeting the mTOR/p-4E-BP1/p-S6K1 pathway in ATC cells. Given these, miR-99a may serve as a novel prognostic/diagnostic and therapeutic target for treating ATC.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제37권2호
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• pp.97-108
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• 2011

Cancer stem cells have stem cell-like features, such as the ability for self-renewal and differentiation but show unlimited growth because they have the lost normal regulation of cell growth. Cancer stem cells and normal stem cells have similar features. They show high motility, diversity of progeny, robust proliferative potential, association with blood vessels, immature expression profiles, nestin expression, epidermal growth factor (EGF)-receptor expression, phosphatase and tensin homolog (PTEN) expression, hedgehog pathway activity, telomerase activity, and Wnt pathway activity. On the other hand, with cancer cells, some of these signaling pathways are abnormally modified. In 1875, Cohnheim suggested the concept of cancer stem cells. Recently, evidence for the existence of cancer stem cells was identified. In 1994, the cancer stem cells' specific cell surface marker for leukemia was identified. Since then, other specific cell surface markers for cancer stem cells in solid tumors (e.g. breast and colon cancer) have been identified. In oral cancer, studies on cancer stem cells have been performed mainly with squamous cell carcinomas. Oral cancer specific cell surface markers, which are genes strongly expressed in oral cancer and cancer stem cell specific side populations, have been identified. Cancer stem cells are resistant to radiotherapy and chemotherapy. Therefore, to eliminate malignant tumors efficiently and reduce the recurrence rate, therapy targeting cancer stem cells needs to be performed. Currently, studies targeting the cancer stem cells' specific signaling pathways, telomerase and tumor vasculatures are being done.

• Interdisciplinary Bio Central
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• 제4권2호
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• pp.3.1-3.7
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• 2012

Epidermal growth factor receptor (EGFR) is a member of the ErbB family (ErbB1-4) of receptor tyrosine kinases (RTKs). EGFR controls numerous physiological functions, including cell proliferation, migration, differentiation and survival. Importantly, aberrant signaling by EGFR has been linked to human cancers in which EGFR and its various ligands are frequently overexpressed or mutated. EGFR coordinates activation of multiple downstream factors and is subject of various regulatory processes as it mediates biology of the cell it resides in. Therefore, many studies have been devoted to understanding EGFR biology and targeting the protein for the goal of controlling tumor in clinical settings. Endocytic regulation of EGFR offers a promising area for targeting EGFR activity. Upon ligand binding, the activated receptor undergoes endocytosis and becomes degraded in lysosome, thereby terminating the signal. En route to lysosome, the receptor becomes engaged in activating various signaling pathways including PI-3K, MAPK and Src, and endocytosis may offer both spatial and temporal regulation of downstream target activation. Therefore, endocytosis is an important regulator of EGFR signaling, and increasing emphasis is being placed on endocytosis in terms of cancer treatment and understanding of the disease. In this review, EGFR signaling pathway and its intricate regulation by endocytosis will be discussed.

• Journal of Yeungnam Medical Science
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• 제37권4호
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• pp.269-276
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• 2020

Fibrosis is characterized by excessive accumulation of extracellular matrix components. The fibrotic process ultimately leads to organ dysfunction and failure in chronic inflammatory and metabolic diseases such as pulmonary fibrosis, advanced kidney disease, and liver cirrhosis. Idiopathic pulmonary fibrosis (IPF) is a common form of progressive and chronic interstitial lung disease of unknown etiology. Pathophysiologically, the parenchyma of the lung alveoli, interstitium, and capillary endothelium becomes scarred and stiff, which makes breathing difficult because the lungs have to work harder to transfer oxygen and carbon dioxide between the alveolar space and bloodstream. The transforming growth factor beta (TGF-β) signaling pathway plays an important role in the pathogenesis of pulmonary fibrosis and scarring of the lung tissue. Recent clinical trials focused on the development of pharmacological agents that either directly or indirectly target kinases for the treatment of IPF. Therefore, to develop therapeutic targets for pulmonary fibrosis, it is essential to understand the key factors involved in the pathogenesis of pulmonary fibrosis and the underlying signaling pathway. The objective of this review is to discuss the role of kinase signaling cascades in the regulation of either TGF-β-dependent or other signaling pathways, including Rho-associated coiled-coil kinase, c-jun N-terminal kinase, extracellular signal-regulated kinase 5, and p90 ribosomal S6 kinase pathways, and potential therapeutic targets in IPF.

• Biomolecules & Therapeutics
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• 제26권3호
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• pp.313-321
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• 2018

Anti-cancer drug resistance is a major problem in colorectal cancer (CRC) research. Although several studies have revealed the mechanism of cancer drug resistance, molecular targets for chemotherapeutic combinations remain elusive. To address this issue, we focused on the expression of cellular prion protein ($PrP^C$) in 5-FU-resistant CRC cells. In 5-FU-resistant CRC cells, $PrP^C$ expression is significantly increased, compared with that in normal CRC cells. In the presence of 5-FU, $PrP^C$ increased CRC cell survival and proliferation by maintaining the activation of the PI3K-Akt signaling pathway and the expression of cell cycle-associated proteins, including cyclin E, CDK2, cyclin D1, and CDK4. In addition, $PrP^C$ inhibited the activation of the stress-associated proteins p38, JNK, and p53. Moreover, after treatment of 5-FU-resistant CRC cells with 5-FU, silencing of $PrP^C$ triggered apoptosis via the activation of caspase-3. These results indicate that $PrP^C$ plays a key role in CRC drug resistance. The novel strategy of combining chemotherapy with $PrP^C$ targeting may yield efficacious treatments of colorectal cancer.

• Journal of Ginseng Research
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• 제42권2호
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• pp.233-237
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• 2018

• BMB Reports
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• 제52권7호
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• pp.415-423
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• 2019

Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription factor that regulates cell proliferation, differentiation, apoptosis, angiogenesis, inflammation and immune responses. Aberrant STAT3 activation triggers tumor progression through oncogenic gene expression in numerous human cancers, leading to promote tumor malignancy. On the contrary, STAT3 activation in immune cells cause elevation of immunosuppressive factors. Accumulating evidence suggests that the tumor microenvironment closely interacts with the STAT3 signaling pathway. So, targeting STAT3 may improve tumor progression, and anti-cancer immune response. In this review, we summarized the role of STAT3 in cancer and the tumor microenvironment, and present inhibitors of STAT3 signaling cascades.

• The Korean Journal of Physiology and Pharmacology
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• 제26권5호
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• pp.367-375
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• 2022

Gastric cancer stem cells (GCSCs) are a major cause of radioresistance and chemoresistance in gastric cancer (GC). Therefore, targeting GCSCs is regarded as a powerful strategy for the effective treatment of GC. Atorvastatin is a widely prescribed cholesterol-lowering drug that inhibits 3-hydroxy-3-methylglutaryl-coenzyme A reductase, a rate-limiting enzyme in the mevalonate pathway. The anticancer activity of atorvastatin, a repurposed drug, is being investigated; however, its therapeutic effect and molecular mechanism of action against GCSCs remain unknown. In this study, we evaluated the anticancer effects of atorvastatin on MKN45-derived GCSCs. Atorvastatin significantly inhibited the proliferative and tumorsphere-forming abilities of MKN45 GCSCs in a mevalonate pathway-independent manner. Atorvastatin induced cell cycle arrest at the G0/G1 phase and promoted apoptosis by activating the caspase cascade. Furthermore, atorvastatin exerted an antiproliferative effect against MKN45 GCSCs by inhibiting the expression of cancer stemness markers, such as CD133, CD44, integrin α6, aldehyde dehydrogenase 1A1, Oct4, Sox2, and Nanog, through the downregulation of β-catenin, signal transducer and activator of transcription 3, and protein kinase B activities. Additionally, the combined treatment of atorvastatin and sorafenib, a multi-kinase targeted anticancer drug, synergistically suppressed not only the proliferation and tumorsphere formation of MKN45 GCSCs but also the in vivo tumor growth in a chick chorioallantoic membrane model implanted with MKN45 GCSCs. These findings suggest that atorvastatin can therapeutically eliminate GCSCs.

• Journal of Ginseng Research
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• 제44권5호
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• pp.725-737
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• 2020

Background: T-cell acute lymphoblastic leukemia (T-ALL) is a kind of aggressive hematological cancer, and the PI3K/Akt/mTOR signaling pathway is activated in most patients with T-ALL and responsible for poor prognosis. 20(S)-Ginsenoside Rh2 (20(S)-GRh2) is a major active compound extracted from ginseng, which exhibits anti-cancer effects. However, the underlying anticancer mechanisms of 20(S)-GRh2 targeting the PI3K/Akt/mTOR pathway in T-ALL have not been explored. Methods: Cell growth and cell cycle were determined to investigate the effect of 20(S)-GRh2 on ALL cells. PI3K/Akt/mTOR pathway-related proteins were detected in 20(S)-GRh2-treated Jurkat cells by immunoblotting. Antitumor effect of 20(S)-GRh2 against T-ALL was investigated in xenograft mice. The mechanisms of 20(S)-GRh2 against T-ALL were examined by cell proliferation, apoptosis, and autophagy. Results: In the present study, the results showed that 20(S)-GRh2 decreased cell growth and arrested cell cycle at the G1 phase in ALL cells. 20(S)-GRh2 induced apoptosis through enhancing reactive oxygen species generation and upregulating apoptosis-related proteins. 20(S)-GRh2 significantly elevated the levels of pEGFP-LC3 and autophagy-related proteins in Jurkat cells. Furthermore, the PI3K/Akt/mTOR signaling pathway was effectively blocked by 20(S)-GRh2. 20(S)-GRh2 suppressed cell proliferation and promoted apoptosis and autophagy by suppressing the PI3K/Akt/mTOR pathway in Jurkat cells. Finally, 20(S)-GRh2 alleviated symptoms of leukemia and reduced the number of white blood cells and CD3 staining in the spleen of xenograft mice, indicating antitumor effects against T-ALL in vivo. Conclusion: These findings indicate that 20(S)-GRh2 exhibits beneficial effects against T-ALL through the PI3K/Akt/mTOR pathway and could be a natural product of novel target for T-ALL therapy.