• BMB Reports
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• 제50권7호
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• pp.379-383
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• 2017

We previously reported that p53 plays a role as a key regulator in the tetraploid G1 checkpoint, which is activated by actin damage-induced cytokinesis blockade and then prevents uncoupled DNA replication and nuclear division without cytokinesis. In this study, we investigated a role of Skp2, which targets CDK2 inhibitor p27/Kip1, in actin damage-induced tetraploid G1 arrest. Expression of Skp2 was reduced, but p27/Kip1 was increased, after actin damage-induced cytokinesis blockade. The role of Skp2 repression in tetraploid G1 arrest was investigated by analyzing the effects of ectopic expression of Skp2. After actin damage, ectopic expression of Skp2 resulted in DNA synthesis and accumulation of multinucleated cells, and ultimately, induction of apoptosis. These results suggest that Skp2 repression is important for sustaining tetraploid G1 arrest after cytokinesis blockade and is required to prevent uncoupled DNA replication and nuclear division without cytokinesis.

• 생명과학회지
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• 제23권6호
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• pp.832-837
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• 2013

본 연구에서는 생체 내 구성요소 및 에너지원으로서 중요한 역할을 하는 글루타민 결핍에 의한 인체 전립선 PC3 암세포의 증식에 관한 기전 연구를 실시하였다. 글루타민 결핍에 의한 PC3 세포의 증식억제는 세포주기 G2/M arrest와 연관성이 있었으나, apoptosis 유발 현상은 관찰되지 않았다. 글루타민 결핍에 의한 G2/M arrest는 전사 및 번역 수준에서 Cdc2, cyclin A 및 cyclin B1의 발현 억제 및 p53 비의존적인 p21(WAF1/CIP1)의 발현 증가와 연관성이 있었다. 아울러 글루타민 결핍은 Chk1 및 Chk2의 인산화를 증가시켰으나, Cdc25C의 인산화는 감소시켰다. 본 연구의 결과는 글루타민 결핍에 의한 PC3 세포의 증식억제가 apoptosis 유발과는 상관없이 G2/M arrest를 유발시킨다는 첫 번째 증거이다.

• 생명과학회지
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• 제26권9호
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• pp.1015-1021
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• 2016

Pyrimidine 유도체의 일종인 5-fluorouracil (5-FU)은 광범위하게 사용되는 항암제의 일종으로, thymidylate synthase의 활성을 억제시켜 핵산의 합성 및 대사기능 자애 유발 물질이다. 본 연구에서는 Ewing′s 육종 CHP-100 세포에서 5-FU의 증식억제와 연관된 기전 해석으로 시도하였다. 본 연구의 결과에 의하면, 5-FU 처리 시간의 경과에 따른 CHP-100 세포의 증식억제가 세포주기 G1 arrest 유발에 따른 것임을 알 수 있었다. 5-FU에 의한 CHP-100 세포의 G1 arrest는 retinoblastoma protein (pRB)의 탈인산화에 따른 전사인자 E2F-1 및 E2F-4와의 결합 촉진과 연관성이 있었다. 비록 5-FU 처리가 cyclin-dependent kinases의 발현에는 크게 영향을 주지 않았으나, 정상배지에서 배양된 대조군에 비하여 cyclin A 및 B의 발현이 5-FU 처리 시간 의존적으로 억제되었다. 또한 5-FU에 의한 CHP-100 세포의 G1 arrest는 apoptosis 유도와 연관이 있음을 핵 내 염색질의 응축에 따른 apoptotic body의 형성증가, poly (ADP-ribose) polymerase의 단편화 및 annexin V 염색 등을 통하여 확인하였다. 아울러 5-FU는 pro-apoptotic Bax 단백질의 발현 증가 및 anti-apoptotic Bcl-2의 발현 감소를 통한 mitochondrial membrane potential의 소실을 촉진시켰으며, 이로 인하여 미토콘드리아에서 세포질로의 cytochrome c 유리가 증가시켰음을 알 수 있었다. 따라서 본 연구의 결과는 5-FU에 의한 CHP-100 세포의 증식억제와 연관된 G1 arrest 및 apoptosis 유도에는 pRB의 인산화 억제 및 미토콘드리아 기능의 손상이 최소한 관여하고 있음을 의미하는 것이다.

• 대한의생명과학회지
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• 제29권4호
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• pp.287-295
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• 2023

Amifostine was developed to protect cells, but it is known to induce cytotoxicity and apoptosis, and the exact mechanism is unknown. In this study, we investigated how the DNA mismatch repair (MMR) system interacts with p53 to prevent apoptosis, cell cycle arrest, and cytoprotective effects induced by amifostine. HCT116 colon cancer cells sublines HCT116/p53+,HCT116/p53+, HCT116/p53-, HCT116/E6 and HCT116+ch3/E6 cells were used for evaluation. Amifostine induced G1 arrest and increased toxicity two-fold in p53- cells regardless of MMR expression. Both G1 cell cycle arrest and induction of p53 protein peaked at 24 h after the start of amifostine exposure. Both G1 cell cycle arrest and induction of p53 protein peaked at 24 h after the start of amifostine exposure. Amifostine induced the expression of p21 protein in both p53+ and p53- cells. As for apoptosis, compared to p53- cells, p53+ cells showed 3.5~4.2 times resistance to amifostine-induced apoptosis. HCT116+E6 with both p53 and MMR loss showed maximum apoptosis at 48 h, and HCT116+ch3/E6HCT116+ch3/E6 with p53 loss showed maximum apoptosis at 24 h. As a result, it was confirmed through in vitro experiments that amifostine-induced G1 cell cycle arrest and apoptosis are mediated through a pathway dependent on MMR and p53 protein.

• Fisheries and Aquatic Sciences
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• 제24권1호
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• pp.1-9
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• 2021

Human prostate cancer is the second most frequently diagnosed cancer worldwide, and its incidence rate continues to increase. Advanced prostate cancer is more difficult to treat than early forms due to its chemotherapy resistance. There is need for more effective agents that can inhibit the progression of advanced prostate cancer. Demethoxyfumitremorgin C (DMFTC) was isolated from the fermentation extract of the marine fungus Aspergillus fumigatus. Antiproliferative activity of DMFTC against human prostate cancer PC3 cells was examined through cell cycle analysis by flow cytometry, the fluorescent nuclear imaging analysis with propidium iodide (PI), and proteins expression related to cell cycle arrest and apoptosis were investigated via Western blotting. DMFTC inhibited PC3 cells growth through G1 phase cell cycle arrest and apoptosis induction. It activated the tumor suppressor p53 and the Cdk inhibitor p21, which regulate the cell progression into the G1 phase. Additionally, PI-positive late apoptotic non-viable cells were increased and the expression levels of the G1-positive downstream regulators cyclin D, cyclin E, Cdk2, and Cdk4 were decreased by DMFTC treatment. These results suggest that DMFTC induces G1 arrest and apoptosis induction through regulation of p53/p21-dependent cyclin-Cdk complexes, and it may be a useful therapeutic agent for the treatment of human advanced prostate cancer.

• 동의생리병리학회지
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• 제22권4호
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• pp.821-828
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• 2008

Onchungeum, a herbal formula, which has been used for treatment of anemia due to bleeding, discharging blood and skin disease. In the present study, it was examined the effects of extract of Onchungeum (OCE) on the growth of human hepatocarcinoma cell lines Hep3B (p53 null type) and HepG2 (p53 wild type) in order to investigate the anti-proliferative mechanism by OCE. Treatment of Hep3B and HepG2 cells to OCE resulted in the growth inhibition in a dose-dependent manner, however Hep3B cell line exhibited a relatively strong anti-proliferative activity to OEC. Flow cytometric analysis revealed that OCE treatment in Hep3B cells caused G1 phase arrest of the cell cycle, which was associated with various morphological changes in a dose-dependent fashion. RT-PCR and immunoblotting data revealed that treatment of OCE caused the down-regulation of cyclin D1 expression, however the levels of cyclin E expression were not changed by OCE. The G1 arrest of the cell cycle was also associated with the induction of Cdk inhibitor p27 by OCE. Because the p53 gene is null in Hep3B cells, it is most likely that the induction of p21 is mediated through a p53-independent pathway. Moreover, p27 detected in anti-Cdk4 and anti-Cdk2 immunoprecipitates from the OCE-treated cells, suggesting that OCE-induced p27 protein blocks Cdk kinase activities by directing binding to the cyclin/Cdk complexes. Furthermore, OCE treatment potently suppresses the phosphorylation of retinoblastoma proteins and the levels of the transcription factor E2F-1 expression. Taken together, these results indicated that the growth inhibitory effect of OCE in Hep3B hepatoma cells was associated with the induction of G1 arrest of the cell cycle through regulation of several major growth regulatory gene products.

• 생명과학회지
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• 제20권7호
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• pp.977-982
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• 2010

본 연구에서는 오미자에서 분리된 dibenzocyclooctadiene lignan의 일종인 gomisin A와 gomisin N에 대한 항암효능을 U937 인체혈구암세포를 대상으로 조사하였다. Gomisin N은 처리농도의 증가에 따라 U937 세포의 증식을 억제하였으나 동일조건에서 gomisin A는 세포독성 효과를 나타내지 못하였으며, gomisin N에 의한 U937 세포의 증식억제는 세포주기 G1 arrest 유발에 의한 것이었다. Gomisin N에 의한 G1 arrest는 cyclin E, cyclin-dependent kinase (Cdk) 2 및 Cdk4의 발현 억제와 Cdk inhibitor인 p16 (INK4A) 및 p21 (WAF1/CIP1)의 발현 증가와 연관성이 있었으나, gomisin A는 세포주기 인자들의 발현에 유의적인 변화를 유발하지 않았다. 또한 gomisin N은 retinoblastoma 단백질군인 pRB 및 p130의 인산화를 억제하였으며, 전사조절인자인 E2F 단백질들의 발현을 억제하였다. 본 연구의 결과에서 gomisin N에 의한 U937 세포의 증식억제는 세포주기 조절인자들의 발현 변화를 통한 G1 arrest 유발에 의한 것임을 알 수 있었으며, gomisin N은 암예방 및 항암활성 후보불질로서의 개발 가능성이 있음을 알 수 있었다.

• 동의생리병리학회지
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• 제21권1호
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• pp.204-208
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• 2007

Chaga mushroom extract is well known as immune modulator and anti-cancer agent. However, the molecular mechanism by which Chaga exerts cell cycle arrest and apoptosis of cancer cells is poorly understood. In this study, we demonstrated anti-proliferative effects of Chaga extract on murine melanoma B16 cells. Chaga extract dose-dependently inhibited cell growth along with the arrest of G0/G1 phase and the induction of apoptotic cell death. Treatment with Chaga extract resulted in a decrease of cyclin E, cyclin D1, cdk 2, cdk 4 expression levels. Furthermore, in vivo inoculation study of B16 melanoma cells into Balb/c mice Chaga extract markedly suppressed the metastatic growth of tumor cells (6 folds, p<0.05,). These results indicate that Chaga mushroom extract induces apoptosis of B16 melanoma cells through arrest of G0/G1 phase in cell cycle.

• Natural Product Sciences
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• 제19권2호
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• pp.155-159
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• 2013

Honokiol, a naturally occurring neolignan mainly found in Magnolia species, has exhibited a potential anti-proliferative activity in human cancer cells. However, the growth inhibitory activity against hepatocellular carcinoma cells and the underlying molecular mechanisms has been poorly determined. The present study was designed to examine the anti-proliferative effect of honokiol in SK-HEP-1 human hepatocellular cancer cells. Honokiol exerted anti-proliferative activity with cell-cycle arrest at the G0/G1 phase and sequential induction of apoptotic cell death. The cell-cycle arrest was well correlated with the down-regulation of checkpoint proteins including cyclin D1, cyclin A, cyclin E, CDK4, PCNA, retinoblastoma protein (Rb), and c-Myc. The increase of sub-G1 peak by the higher concentration of honokiol ($75{\mu}M$) was closely related to the induction of apoptosis, which was evidenced by decreased expression of Bcl-2, Bid, and caspase-9. Hohokiol was also found to attenuate the activation of signaling proteins in the Akt/mTOR and ERK pathways. These findings suggest that the anti-proliferative effect of honokiol was associated in part with the induction of cell-cycle arrest, apoptosis, and dow-nregulation of Akt/mTOR signaling pathways in human hepatocellular cancer cells.

• 동의생리병리학회지
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• 제21권6호
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• pp.1555-1563
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• 2007

To idenifty effect of Bojungbangam-tang kakambang on Cisplatin-Induced G2/M Phase Arrest in Human Renal Proximal Tubular HK-2 Cells. Cytotoxicity of cisplatin was detected in HK-2 cells and the value of IC50 is about $25\;{\mu}M$. The treatment of cisplatin to HK-2 showed the G2/M phase cell cycle arrest. The ethanol extract of Bojungbangam-tang kakambang (EBTKB), a new herbal prescription composed of ten crude herbs, inhibited cisplatin-induced G2/M phase arrest in HK-2 cells. EBTKB increased G0/G1 peak in cisplatin-treated HK-2 cells. p53, p21 and p27 expression were increased in cisplatin-treated HK-2 cells. Inhibitory effect of EBTKB on cisplatin-induced G2/M phase arrest was accomplished through inhibition of p53, p21 and p27 expression. Also, reduced CDK2 and cyclin A expression by cisplatin were increased by EBTKB, but cyclin E was not changed. Reduction of ERK activation and increment of p38 activation by cisplatin were increased ERK activation and decreased p38 activation by EBTKB. Cisplatin had no effect on JNK activation, but EBTKB increased JNK activation. These results can suggest that EBTKB inhibits cisplatin-induced G2/M phase arrest in HK-2 cell through reduction of p53-dependent p21 and p27 protein, ERK activation and p38 inactivation.