• 동의생리병리학회지
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• 제20권6호
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• pp.1530-1537
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• 2006

Platycodi Radix, the root of Platycodon grandiflorum A. DC (Campanulaceae), commonly known as Doraji in Korea (Chinese name, 'Jiegeng', and Japanese name, 'Kikyo') has been used as an expectorant in traditional Oriental medicine. Extracts from the roots of P. grandiflorum have been reported to have wide ranging health benefits. In Korea, Platycodi Radix is also used as a food and employed as a folk remedy for adult diseases, such as bronchitis, asthma and pulmonary tuberculosis, hyperlipidemia, diabetes, and inflammatory diseases, and as a sedative. Several studies on its chemical and immunopharmacological effects including immunostimulation and antitumor activity have been performed. However, the relevant molecular mechanisms are poorly understood. Platycodi Radix, the root of Platycodon grandiflorum A. DC (Campanulaceae), commonly known as Doraji in Korea (Chinese name, 'Jiegeng', and Japanese name, 'Kikyo') has been used as an expectorant in traditional Oriental medicine. Extracts from the roots of P. grandiflorum have been reported to have wide ranging health bensfits. In Korea, Platycodi Radix is also used as a food and employed as a folk remedy for adult diseases, such as bronchitis, asthma and pulmonary tuberculosis, hyperlipidemia, diabetes, and inflammatory diseases, and as a sedative. Several studies on its chemical and immunopharmacological effects including immunostimulation and antitumor activity have been performed. However, the relevant molecular mechanisms are poorly understood. In the present study, we investigated the effects of an aqueous extract from the roots of P. grandiflorum AEPG) on the cell growth of human lung adenocarcinoma NCI-H460 cells in order to understand its anti-proliferative mechanism. AEPG treatment down-regulated the cyclin D1 expression in both transcriptional and translational levels without alteration of cyclin E. In AEPG-treated cells, the levels of cyclin-dependent kinase (C아) 6 mRNA and protein were significantly inhibited, but the levels of Cdk2 and Cdk4 were slightly inhibited by treatment of AEPG. AEPG treatment induced a marked accumulation of Cdk inhibitors, p16 and p27. However, AEPG treatment did not affect not only retinoblastoma protein (pRB) but also tumor suppressor p53 protein expression. The present results indicated that AEPG-induced inhibition of lung cancer cell proliferation is associated with the blockage of G1 phase progression through induction of Cdk inhibitors such as p16 and p27, and inhibition of cyclin D1 and Cdk6. AEPG exposure, as offered by this study, provides cluse for the mechanism of AEPG action. Taken together, these findings suggest that P. grandiflorum has strong potential for development as an agent for prevention and treatiment against human lung cancer.

• Journal of Microbiology and Biotechnology
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• 제33권9호
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• pp.1206-1212
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• 2023

The Wnt/β-catenin pathway plays essential roles in regulating various cellular behaviors, including proliferation, survival, and differentiation [1-3]. The intracellular β-catenin level, which is regulated by a proteasomal degradation pathway, is critical to Wnt/β-catenin pathway control [4]. Normally, casein kinase 1 (CK1) and glycogen synthase kinase-3β (GSK-3β), which form a complex with the scaffolding protein Axin and the tumor suppressor protein adenomatous polyposis coli (APC), phosphorylate β-catenin at Ser45, Thr41, Ser37, and Ser33 [5, 6]. Phosphorylated β-catenin is ubiquitinated by the β-transducin repeat-containing protein (β-TrCP), an F-box E3 ubiquitin ligase complex, and ubiquitinated β-catenin is degraded via a proteasome pathway [7, 8]. Colorectal cancer is a significant cause of cancer-related deaths worldwide. Abnormal up-regulation of the Wnt/β-catenin pathway is a major pathological event in intestinal epithelial cells during human colorectal cancer oncogenesis [9]. Genetic mutations in the APC gene are observed in familial adenomatous polyposis coli (FAP) and sporadic colorectal cancers [10]. In addition, mutations in the N-terminal phosphorylation motif of the β-catenin gene were found in patients with colorectal cancer [11]. These mutations cause β-catenin to accumulate in the nucleus, where it forms complexes with transcription factors of the T-cell factor/lymphocyte enhancer factor (TCF/LEF) family to stimulate the expression of β-catenin responsive genes, such as c-Myc and cyclin D1, which leads to colorectal tumorigenesis [12-14]. Therefore, downregulating β-catenin response transcription (CRT) is a potential strategy for preventing and treating colorectal cancer. Plant cytokinins are N⁶-substituted purine derivatives; they promote cell division in plants and regulate developmental pathways. Natural cytokinins are classified as isoprenoid (isopentenyladenine, zeatin, and dihydrozeatin), aromatic (benzyladenine, topolin, and methoxytopolin), or furfural (kinetin and kinetin riboside), depending on their structure [15, 16]. Kinetin riboside was identified in coconut water and is a naturally produced cytokinin that induces apoptosis and exhibits antiproliferative activity in several human cancer cell lines [17]. However, little attention has been paid to kinetin riboside's mode of action. In this study, we show that kinetin riboside exerts its cytotoxic activity against colon cancer cells by suppressing the Wnt/β-catenin pathway and promoting intracellular β-catenin degradation.

• 생명과학회지
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• 제23권10호
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• pp.1230-1238
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• 2013

$17{\alpha}$-estradiol ($17{\alpha}-E_2$)의 에폽토시스 유도활성에 미치는 종양억제단백질 p53의 조절효과를 조사하고자, $17{\alpha}-E_2$에 의해 유도되는 에폽토시스 현상들을 인체 대장암 세포주 유래 클론인 HCT116 ($p53^{+/+}$) 및 HCT116 ($p53^{-/-}$) 세포에서 비교하였다. HCT116 ($p53^{+/+}$) 및 HCT116 ($p53^{-/-}$) 세포를 $17{\alpha}-E_2$ ($2.5{\sim}10{\mu}M$)로 처리하거나 혹은 HCT116 ($p53^{+/+}$) 및 HCT116 ($p53^{-/-}$) 세포를 $10{\mu}M$ $17{\alpha}-E_2$로 시간 별로 처리한 결과, HCT116 ($p53^{+/+}$)에 있어서는 세포독성과 에폽토시스-관련 sub-G1 peak의 비율은 처리농도와 시간에 의존적으로 나타났다. 그러나 HCT116 ($p53^{-/-}$) 세포의 경우는 이러한 현상이 미약하게 나타났다. $17{\alpha}-E_2$에 의해 유도되는 비정상적 유사분열방추사 형성, 중기판 염색체 배열의 미완성, 이에 따른 유사분열정지($G_2/M$ arrest) 등의 현상은 HCT116 ($p53^{+/+}$) 및 HCT116 ($p53^{-/-}$) 세포에서 유사한 수준으로 나타났다. 이에 반해, $17{\alpha}-E_2$에 의해 유도되는 Bak과 Bax의 활성화, 미토콘드리아의 막전위 상실(${\Delta}{\Psi}m$ loss), 그리고 PARP 분해 등의 현상은 HCT116 ($p53^{-/-}$) 세포에 비해 HCT116 ($p53^{+/+}$) 세포에서 훨씬 높은 수준으로 확인되었다. 아울러 $17{\alpha}-E_2$로 처리된 HCT116 ($p53^{+/+}$) 세포에서 확인되는 p53 (Ser-15)의 인산화 및 p53 수준의 증가와 일치하여, 세포 내의 p21및 Bax 수준도 현저히 증가하였다. 이때 $17{\alpha}-E_2$로 처리된 HCT116 ($p53^{-/-}$) 세포에서는 p21 및 Bax의 발현수준이 매우 낮았다. 한편, 에폽토시스 억제단백질인 Bcl-2 단백질 수준은 HCT116 ($p53^{-/-}$) 세포에 비해 HCT116 ($p53^{+/+}$) 세포에서 다소 낮았으나, 이러한 Bcl-2 단백질 수준은 $17{\alpha}-E_2$ 처리 후에도 크게 변화하지 않는 것으로 나타났다. 이러한 결과들은 $17{\alpha}-E_2$ 처리에 의해 유도되는 에폽토시스 유도 경로의 구성원들의 변화, 즉 비정상적 유사분열방추사 형성 및 이에 따른 유사분열정지($G_2/M$ arrest), 뒤이은 Bak 및 Bax의 활성화, 미토콘드리아의 막전위 상실, 그리고 이에 수반되는 caspase cascade 활성화 및 PARP 분해로 진행되는 에폽토시스 현상들 중에서, Bak 및 Bax의 활성화 단계가 종양억제단백질 p53의 에폽토시스 증진 활성에 의해 양성적으로 조절되는 작용 타켓임을 보여준다.

• 생명과학회지
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• 제21권6호
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• pp.796-804
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• 2011

본 연구에서는 파의 항염증 효과를 밝히고 그 생화학적 기전 해석을 위해 LPS로 활성화된 BV2 microglia를 이용하여 iNOS, COX-2 및 염증성 cytokine의 발현 및 그 산물에 미치는 파 추출물의 영향을 조사하였다. 그 결과 파 추출물은 LPS 처리에 의한 BV2 세포의 iNOS의 발현을 전사 및 번역 수준에서 처리 농도 의존적으로 억제시켰으며, 특히 파 전체 에탄올 추출물(EEWA)의 효과가 가장 탁월하였다. LPS로 유도한 COX-2의 mRNA 및 단백질 발현 역시 파 추출물 처리에 의하여 감소되었으며 뿌리 에탄올 추출물(EERA) 처리군에서 가장 현저한 억제가 관찰되었다. 아울러 염증 반응의 또 다른 주요인자인 염증성 cytokine들(TNF-${\alpha}$, IL-$1{\beta}$ 및 IL-6)의 mRNA 변화를 조사한 결과 파 추출물이 대체적으로 이들 cytokine의 발현을 억제하는 경향을 보였으며, 최종산물인 TNF-${\alpha}$와 IL-6의 생성량 역시 유의한 수준은 아니었으나 감소하는 경향을 보였다. 본 연구의 결과는 파의 추출물은 iNOS, COX-2 및 염증성 cytokine의 발현을 조절함으로서 신경염증 반응을 효과적으로 억제하며, 향후 지속적인 연구가 필요하지만 신경 보호 작용에 탁월한 효능이 있음을 보여주는 것으로 생각된다.