• Radiation Oncology Journal
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• 제16권4호
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• pp.377-388
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• 1998

목적 : 방사선조사에 의한 apoptosis에서 나타나는 각종 세포주기관련 유전자들의 발현 양상을 RNA와 단백 수준에서 분석하여 방사선조사에 의한 apoptosis에서의 세포주기 조절의 변화를 규명함으로서 방사선치료의 기전에 대한 분자생물학적 이해를 도모하고자 본 연구를 시행하였다. 대상 및 방법 : promyelocytic leukemia 세포주인 HL60 세포주를 배양하여 선형가속기(6MV X-선)로 세포에 8Gy의 방사선을 조사하였다. 조사후 다양한 시간 간격으로 Apoptotic DNA Fragmentation Assay법을 이용하여 apoptosis를 확인하고 동시에 세포주기관련 유전자들(cyclinA, cyclin B, cyclin C, cyclin Dl, cyclin E, cdc2, CDK2, CDK4, $p16^{INK4a}$, $p21^{WAF1}$, $p27^{KIP1}$, E2F, PCNA와 Rb)을 단백질과 RNA 수준에서 분석하기위해 western blot analysis와 반정량적 RT-PCR을 시행하였다. 결과: 8 Gy의 방사선 조사에 의해 HL60세포에서 apoptosis가 관찰 되었다. 방사선 조사군에서 cyclin A단백은 조사후 48시간까지 시간이 갈수록 증가하였으며, cyclin E, E2F, CDK2 및 Rb 단백은 증가되었다가 다시 감소를 보였다. Rb단백의 증가는 대부분 비활성형인 ppRb (phosphorylated Rb protein)의 양적변화에 의한 것이었다. cyclin Dl, PCNA, COC2, CDK4, $p16^{INK4a}$단백은 발현의 차이를 보이지 않았으며 $p21^{WAF1}$과 $p27^{KIP1}$ 단백은 검출되지 않았다. cyclin A, B, C mRNA는 방사선 조사 직후 감소하였다가 12시간부터 발현이 증가되었으며 cyclin Dl mRNA는 조사후 바로 증가하여 48시간에 다시 감소하였다. cyclin E mRNA는 조사 후 시간이 경과함에 따라 감소하였다. CDK2 mRNA는 3시간째는 감소하다가 6시간부터 많은 증가를 보였으며 CDK4 mRNA는 조사후 6-12시간에 급격한 발현증가를 보였다. $p16^{INK4a}$ RNA는 발현의 변화가 없었으며, $p21^{WAF1}$ 및 $p27^{KIP1}$ RNA의 발현은 관찰되지 않았다. 결론 : 이상의 결과로 미루어볼 때, 방사선 조사에 의한 HL60세포의 apoptosis와 세포의 Gl/S transition는 밀접한 관계가 있는 것으로 생각되며 Rb단백의 증가와 활성형 Rb단백의 감소 현상도 관련이 있는 것으로 사료된다. 이는 E2F의 비정상적인 과발현 및 cyclin E/CDK2의 발현 증가와 관련이 있는 것으로 추측된다. 또한 $p21^{WAF1}$ 및 $p27^{KIP1}$는 방사선에 의한 apoptosis에는 관여되지 않는 것으로 사료된다.

• Reproductive and Developmental Biology
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• 제31권2호
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• pp.71-76
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• 2007

Previous studies have shown that BMI-1026 is a potent inhibitor of the cyclin-dependent kinases (cdk). In cell culture, the compound also arrests G2/M strongly and G1/S and S weakly. Two key kinases, cdk1 (p34cdc2 kinase) and mitogen-activated protein (MAP) kinase (erk1 and 2), perform crucial roles during oocyte maturation and, later, metaphase II (MII) arrest. In mammalian oocytes, both kinases are activated gradually around the time of germinal vesicle breakdown (GVBD) and maintain high activity in eggs arrested at metaphase II. In this study, we examined the effects of BMI-1026 on GVBD and MII arrest in mouse oocytes. BMI-1026 inhibited GVBD of immature oocytes and activated MII-arrested oocytes in a concentration-dependent manner, with more than 90% of oocytes exhibiting GVBD inhibition and MII activation at 100 nM This is approximately 500$\sim$1,000 times more potent than the activity reported for the cdk inhibitors roscovitine (${\sim}50{\mu}M$) and butyrolactone (${\sim}100{\mu}M$). Based on the results of previous in vitro kinase assays, we expected BMI-1026 to inhibit only cdk1 activation in oocytes and eggs, not MAP kinase. However, in our cell-based system, it inhibited the activity of both kinases. We also found that the effect of BMI-1026 is reversible. Our results suggest that BMI-1026 inhibits GVBD and activates MII-arrested oocytes efficiently and reversibly and that it also inhibits both cdk1/histone HI kinase and MAP kinase in mouse oocytes.

• Animal cells and systems
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• 제11권1호
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• pp.9-15
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• 2007

The naphthoquinone analog (2,3-dichloro-6,9-dihydroxy-1,4-naphtoquinone, NA) has an inhibitory effect on cdc25A protein phosphatase in vitro, which is responsible for G1/S transition during cell cycle. However, the exact mechanism inducing the growth inhibition is not understood. In this study, we investigated the regulatory mechanisms of growth arrest induced by NA, as a new potent inhibitor of cdc25A phosphatase, in human hepatocarcinoma SK-hep-1 cells. We found that NA induced the G1 arrest by perturbation of protein tyrosine dephosphorylation of Cdk2, which may be resulting from inhibition of cdc25A phosphatase. In addition, p21 was expressed in a p53-independent manner and participated in the NA-induced G1 arrest by inhibiting Cdk2 activity. Although the exact mechanism is not known, the p21 expression might be related to MAPK activation. From these results, we suggest that NA induces G1 arrest via inhibition of cdc25A and induction of p53-independent p21 expression in SK-Hep-1 cells.

• 한국식품영양과학회지
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• 제33권8호
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• pp.1237-1245
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• 2004

브라질 기원인 신령 버섯 (A. blazei murill)은 강력한 항암 및 면역강화 작용을 가진 것으로 알려져 있다. 본 연구에서는 신령버섯 수용성 추출물(water extracted A. blazei Murill, WEAB)이 A549 인체 폐암세포 증식에 미치는 영향을 조사하였으며, 증식억제와 연관된 기전 해석을 시도하였다. WEAB가 처리된 A549 세포는 처리 농도 의존적으로 생존율이 감소되었으며, WEAB 처리는 암세포의 다양한 형태적 변형을 유발하였다. Flow cytometry 분석 결과로서 WEAB 처리에 의한 A549 폐암세포의 증식억제는 세포주기 G2/M arrest 및 apoptosis 유발과 직접적으로 연관성이 있음을 알 수 있었다. WEAB가 처리된 암세포에서 전사 및 번역 수준에서 cyclin A 발현의 감소 및 Cdk inhibitor p21 발현의 증가 현상이 관찰되었으나, cyclin B1, Cdk2, Cdc2, Wee1, Cdc25c 및 p53 등의 발현에는 큰 변화가 관찰되지 못하였다. 또한 WEAB의 처리는 COX-2 선택적 발현 저하를 유발하였으나, telomere 조절 관련 유전자들의 발현에는 큰 영향을 주지 못하였다. 이상의 결과는 신령버섯 추출물이 강력한 항암 및 암 예방 효능의 잠재력을 가지고 있음을 의미하며, 이에 관한 지속적인 연구가 필요할 것으로 생각된다.

• 생명과학회지
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• 제11권4호
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• pp.362-370
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• 2001

Regulation of cell proliferation is a complex process involving the regulated expression and /or modification of discrete gene products. which control transition between different stages of the cycle. The purpose of this short review is to provide an overview of somatic cell cycle events and their controls. Cycline have appeared as major positive regulators in this network, because their association to the cyclin-dependent kinases(Cdks) allows the subsequent activation on the Cdk/cyclin complexes and their catalatic activity. In mammalian cells, early to mid G1 progression and late G1 progression leading to S phase entry are directed by D-type cyclins-Cdk4, 6 and cyclin E-Cdk 2 both of which can phosphorylate the retinoblastoma protein (pRB). pRB is a transcriptional repressor which, in its unphosphorylated state, binds to members of the E2F transcription factor family and blocks E2F-dependent transcription of genes controlling the G1 to S phase transition an subsequent DNA synthesis. Cyclin A is produced in late G1 and expressed during S and G2 phae, and expression of B-type cyclins is typically maximal during the G2 to M phase transition and it controls the passage through M phase. They primarily associate with the activate Cdk2, and Cdc2, respectively. On the other hand, the Cdk inhibitors negatively control the activity of C아/cyclin complex by coordinating internal and/or external signals and impending proliferation at several key checkpoints. These current and further findings will provide novel approaches to understanding and treating major diseases.

• Asian-Australasian Journal of Animal Sciences
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• 제15권7호
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• pp.1045-1050
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• 2002

The aims of this study were to detect spontaneously occurring apoptosis in cultured porcine ovarian cells, to examine the role of growth hormone (GH), tyrosine kinase (TK), protein kinase G (PKG) and cyclin-dependent kinase (CDK) in the control of this process, and to determine whether the effect of GH on apoptosis is mediated by TK-, PKG- and cdc2-dependent intracellular mechanisms. We studied the action of pGH (10 ng/ml), blockers of TK (genistein, lavendustin, both 100 ng/ml), PKG (Rp-Br-PET-cGMPS, 50 nM; KT5823, 100 ng/ml) and CDK (olomoucine, $1{\mu}g/ml$), as well as combinations of GH with these blockers, on the onset of apoptosis in cultured granulosa cells isolated from antral (3-6 mm) porcine follicles. The functional characteristics of an early apoptotic event, DNA fragmentation, were determined using terminal deoxynucleotidyltransferase (TdT)-mediated dUTP nick end labelling (TUNEL), whilst morphological signs of advanced apoptosis such as pyknosis, chromatin marginalization, shrinkage and fragmentation of nucleus, were detected using routine light microscopy. After culture, some ovarian granulosa cells exhibited DNA fragmentation, which in some cases was associated with morphological apoptosis-related changes (pyknosis, shrinkage and fragmentation of the nucleus). GH significantly reduced the proportion of TUNEL-positive cells. Neither TK nor CDK blockers when given alone, significantly affected the percentage of TUNEL-positive cells although both PKG blockers significantly increased this index. Furthermore, TK and PKG blockers given together with GH, prevented or reversed the inhibitory effect of GH on apoptosis, whilst the CDK blocker olomoucine promoted it. These observations demonstrate apoptosis in porcine ovaries and suggest the involvement of GH, TK, PKG and CDK in the control of this process. They also suggest that the effect of GH on ovarian apoptosis is mediated or regulated by multiple signalling pathways including TK-, PKG- and CDK-dependent intracellular mechanisms.

• Animal cells and systems
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• 제9권4호
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• pp.191-198
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• 2005

The effects of 6-aminonicotinamide (6-AN) on viability of IMR32 neuroblastoma cells in the presence of ATP or $NAD^+$ have been investigated. 6-AN caused marked reduction in cell viability and similar observations were also made with cells treated with 6-AN+ATP. However, cells treated with $6-AN+NAD^+$ showed cell viability similar to untreated cells. Morphologically, 6-AN and 6-AN+ATP treated cells showed loss of neurites, polyhedric shapes, shrinkage of cell bodies and formation of lysed cells, while $6-AN+NAD^+$ cells did not show any such changes. The flow cytometry analysis demonstrated that 6-AN increased cell population in $G_0/G_1$ phase and decreased cell population in Sand $G_2/M$ phase following a 72 h exposure. Western blot analysis showed that 6-AN stimulated a substantial increase in the level of the cdk inhibitor $p27^{kip1}$, but lowered the levels of cdk2, cyclin E and p-Rb. However, cdc25A and p53R2 were not significantly affected. Immunofluorscence staining of $p27^{kip1}$, cdk2, cyclin E and p-Rb revealed close correlation between the signal observed in the Western blot analysis. 6AN+ATP treated cells showed similar results obtained with 6-AN treated cells in expression of cdk2, cyclin E, p-Rb proteins and $p27^{kip1}$, $6-AN+NAD^+$ cells showed greater expression of cdk2, cyclin E and p-Rb than those in 6-AN and 6-AN+ATP treated cells. The results suggest that 6-AN induced the $G_0/G_1$ phase arrest in IMR32 neuroblastoma cell lines through the increase of $p27^{kip1}$ and the decrease of cdk2, cyclin E and p-Rb.

• 한국미생물·생명공학회지
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• 제29권3호
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• pp.181-185
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• 2001

유방암 세포주에서는 우수한 항암활성을 가진 것으로 알려진 indole-3-carbinol을 HepG2세포주에 시간과 농도별로 처리한 결과 cell growth inhibition을 확인하였으며, $IC_{50}$ 값은 48시간배양에서 $446\mu$M 72시간 배양에서 444$\mu$M로 나타났다. $400\mu$M의 I3C을 투여하고, 24, 48, 72시간에 HePG2 세포주의 cell cycle pattern을 분석한 결과, G1 phase에서 P21의증가와 함께 Cdk 6와 cyclin D의 확연한 감소와 Pb protein의 hypo-phosphorylation을 확인하였다. 반면 G2 phase에서는 I3C의 직접적인 억제로 인해 24시간 후부터 Cdc2와 cyclin B1가 급격히 감소하는것을 확인하였다. Flow cytomery 분석결과 I3C 처리 24시간 뒤 G2 arrest (25%)가 발생하였으며, 72시간이 지난후 G1 arrest (53%)가 발생하였다. 이러한 I3C의 간암세포주인 HePG2 cell의 cell cycle arrest가 apoptosis를 유발하는지를 알고자 caspase 3 Bcl2 Bax protein의 발현양상을 확인한 결과 아무런 변화가 보이지 않았다. 즉 I3C은 간암세포주인 HepG2 cell에서 apoptosis를 유도하지 못한다는것을 확인하였따. 결론적으로 I3C은 HepG2 세포주에서 G1와 G2 phase에서 cell cycle arrest는 발생시키나, 특이적으로 apoptosis 와는 연관되지 않는다는 사실을 확인하였다.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.168.1-168.1
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• 2003

We show that panaxadiol (PD), a ginseng saponin with a dammarane skeleton, selectively interferes with the cell cycle in human cancer cell lines. PD inhibited DNA synthesis in a dose-dependent manner with $IC_{50}$ values ranging from 0.8 $\mu$M-1.2 $\mu$M in SK-HEP-1 cells and HeLa cells. PD-treated cells were arrested at G1/S phase, shich coincided well with decreases in Cyclin A-Cdk2 activity, but not in Cyclin E-Cdk2 and Cdc2 activities. The intracellular levels of $p21^{WAF1/CIP1}$ were significantly and selectively elevated in a dose and time-dependent manners in PD-treated HeLa cells. (omitted)

• Biomolecules & Therapeutics
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• 제18권2호
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• pp.178-183
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• 2010

Costunolide is an active compound isolated from the stem bark of Magnolia sieboldii, and is considered a potential therapeutic for the treatment of various cancers. In this study, we investigated the underlying mechanism whereby costunolide induces the apoptosis of human leukemia cells. Using apoptosis analysis and quantitative reverse transcription-polymerase chain reaction (RT-PCR) results obtained during this study show that costunolide is a potent inducer of apoptosis and that it is triggered due to the premature activation of Cdc2. $G_1$-synchronized cells, which cannot undergo mitosis, were found to be more sensitive to costunolide, and Cdc2 mRNA levels were increased by costunolide treatment. Furthermore, the Cdk inhibitors, olomucine and butyrolactone I, were found to suppress costunolide-induced apoptosis. In addition, the PKC activator TPA rescued cells from cell death by costunolide, and this was prevented by the PKC inhibitor staurosporin. The present study suggests that costunolide induces the apoptosis of HL-60 leukemic cells by modulating cyclin-dependent kinase Cdc2.