Intrinsic apoptotic pathway and G2/M cell cycle arrest involved in tubeimoside I-induced EC109 cell death

Objective： Squamous esophageal carcinoma is highly prevalent in developing countries, especially in China. Tu Bei Mu （TBM）, a traditional folk medicine, has been used to treat esophageal squamous cell carcinoma （ESCC） for a long term. tubeimoside I （TBMS1） is the main component of TBM, exhibiting great anticancer potential. In this study, we investigated the mechanism of TBMS1 cytotoxic effect on EC109 cells. Methods： Comparative nuclear proteomic approach was applied in the current study and we identified several altered protein spots. Further biochemical studies were carried out to detect the mitochondrial membrane potential, cell cycle and corresponding proteins＇ expression and location. Results： Subcellular proteomic study in the nucleus from EC109 cells revealed that altered proteins were associated with mitochondrial function and cell proliferation. Further biochemical studies showed that TBMSl-induced molecular events were related to mitochondria-induced intrinsic apoptosis and P21-cyclin B 1/cdc2 complex-related G2/M cell cycle arrest. Conclusions： Considering the conventional application of TBM in esophageal cancer, TBMS1 therefore may have a great potential as a chemotherapeutic drug candidate for ESCC.

Cucurbitacin E inhibits the proliferation of hepatoma cells in vitro and in vivo through induction of G2/M phase arrest

Objective Cucurbitacins are the highly oxygenated tetracyclic triterpenes,which are predominantly found in the Cucurbitaceae family but are also present in several other families of the plant kingdom.A number of compounds of this group have been investigated for their cytotoxic,hepatoprotective,anti-inflammatory,cardiovascular and anti-diabetic activities.In China,the cucurbitacin preparation,which contains mostly cucurbitacin B and cucurbitacin E,has been clinically used for the treatment of the primary liver carcinoma.It has been previously reported that cucurbitacin E could produce cytotoxicity against a variety of cancer cells,and various mechanisms were implicated in its cytotoxic effect.The present study is to investigate the effect of cucurbitacin E on hepatoma cells in vitro and in vivo and to study their potential mechanisms of action.Methods The MTT assay was used to assess the viability of human HepG2 and BEL7402 hepatoma cells in vitro after treatment with different concentrations of cucurbitacin E.The cell cycle distribution was determined by flowcytometric analysis after propidium iodide(PI)staining.The cell cycle-related proteins were detected using western blotting analysis.Implanted mouse hepatoma H22 model was built to evaluate the growth inhibitory effect of cucurbitacin E in vivo in mice.Results Our studies found that cucurbitacin E(10-300 nM)produced anti-proliferative effect on human HepG2 and BEL7402 hepatoma cells in vitro without cytotoxicity.According to flowcytometric analysis,cucurbitacin E arrested the cell cycle at G2/M phase in both HepG2 and BEL7402 hepatoma cells after 24 h treatment.Cucurbitacin E induced the decrease in the level of CDK1 protein and the increase in the level of p21 protein,but had no effect on the levels of cyclin A,cyclin B1 and Cdc25C protein.In in vivo anti-tumor experiment,cucurbitacin E had significant inhibitory effects on the growth of mouse H22 hepatoma cells.Conclusions Cucurbitacin E inhibited the proliferation of hepatoma cells in vitro and in vivo,at least in part,through induction of cell cycle arrest at G2/M phase,which was mediated by concomitant upregulation of p21 and downregulation of CDK1.We consider that cucurbitacin E may be useful in the treatment of liver cancer.

Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis

Objective： To examine the apoptotic effect of ent-llα-hydroxy-15-oxo-kaur-16-en-19-oic-acid （5F）, a compound isolated from Pteris semipinnata L （PsL）, in human lung cancer A549 cells. Methods： A549 cells were treated with 5F （0-80 lag/ml） for different time periods. Cytotoxicity was examined using a Ml-I- method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay （ELISA） and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species （ROS） level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined. Results： 5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor （AIF）, and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin. Conclusion： 5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.

DADS通过Chk1/Cdc25C/CyclinB1/CDK1通路诱导白血病HL-60细胞G2/M期阻滞

目的研究二烯丙基二硫(diallyl disulfide,DADS)诱导人白血病HL-60细胞周期阻滞及其分子机制。方法采用细胞计数、软琼脂克隆形成实验及流式细胞术观察DADS对HL-60细胞生长抑制与周期阻滞效应。Western blot检测DADS对HL-60细胞Chk1/2以及下游分子的影响。结果细胞计数显示,60、120μmol·L-1DADS处理后,其群体倍增时间从19.14 h增加到35.03、71.82 h(P<0.05)。软琼脂克隆形成实验表明,30、60、90、120μmol·L-1DADS对HL-60细胞克隆形成率的抑制率分别为35.06%、62.10%、93.79%、99.35%(P<0.05)。流式细胞术检测显示,60和120μmol·L-1DADS分别作用HL-60细胞24 h后,DADS可呈时间与浓度依赖性诱导HL-60细胞G2/M期阻滞(P<0.05)。60μmol·L-1DADS处理HL-60细胞后,p-Chk1可呈时间依赖性上调(P<0.05),而Chk1与Chk2总蛋白和pChk2无改变(P>0.05)。并且,Cdc25C、CyclinB 1和CDK1分别呈时间依赖性下调(P<0.05),但14-3-3蛋白表达没有改变(P>0.05)。结论 DADS能够抑制HL-60细胞增殖,并通过Chk1/Cdc25C/CyclinB 1/CDK1通路阻滞HL-60细胞于G2/M期。

以人甲胎蛋白启动子控制表达HIV-1vpr基因的重组腺病毒诱导肝癌细胞G2期阻滞和细胞凋亡作用的研究

目的研究人甲胎蛋白(AFP)启动子控制表达HIV-1 vpr基因的重组腺病毒对AFP(+)肝癌细胞G2期阻滞和细胞凋亡的作用,评估以该策略利用vpr进行肿瘤特异性基因治疗的可行性。方法将以AFP启动子控制HIV-1vpr表达的重组腺病毒rvAdAFP-vpr和空白载体rvAd-null分别感染AFP(+)的肝癌细胞BEL-7402和AFP(-)的肝癌细胞SMMC-7721,利用流式细胞仪检测Vpr的特异性表达和细胞周期分布,用细胞荧光染色和线粒体膜电位检测等方法观察细胞凋亡。结果与对照病毒rvAd-null相比,重组腺病毒rvAdAFP-vpr只在AFP(+)肝癌细胞中表达HIV-1Vpr,并诱导肝癌细胞的细胞周期G2期阻滞和细胞凋亡,而在AFP(-)肝癌细胞中不明显表达Vpr,不能显著诱导肝癌细胞G2期阻滞和细胞凋亡。结论重组腺病毒rvAdAFP-vpr对于Vpr的表达是AFP表达特异性的,可有效诱导肝癌细胞G2期阻滞和细胞凋亡,有望用于AFP(+)肝癌的基因治疗研究。

PPI1诱导人宫颈癌HeLa细胞G2／M期停滞及机制研究

目的:探讨Ⅰ型磷酸酶抑制亚基1(PPI1)对人宫颈癌细胞系HeLa细胞周期的影响及其作用机制。方法:分别将PPI1野生型和短片段突变活化型基因通过脂质体介导转染人宫颈癌HeLa细胞,用RT-PCR和Western blot鉴定目的基因的表达;用流式细胞术分析瞬时转染HeLa细胞的细胞周期。对稳定转染的HeLa细胞用脱氧胸苷处理,通过流式细胞术观察PPI1对同步化HeLa细胞的细胞周期进展的影响。用免疫印迹分析细胞周期相关蛋白表达水平的变化。结果:野生型和突变活化型PPI1在HeLa细胞中均能有效表达。突变活化型PPI1基因的瞬时转染可使HeLa细胞G2/M期比例明显升高。经脱氧胸苷处理过的同步化的稳定转染的HeLa细胞中,突变活化型和野生型PPI1均可使HeLa细胞停滞在G2/M期的时间长于对照组,而且前者更明显。免疫印迹显示:突变活化型PPI1瞬时表达48h后,cyclin A、cyclin B1、p53和p21表达上调。经脱氧胸苷同步化并恢复正常培养基后,稳定表达突变活化型PPI1的细胞cyclin B1在10.5和12h,p53在6、7.5、9和10.5h表达明显增强;稳定表达野生型PPI1的细胞cyclin B1在10.5h的表达也比对照组明显增强。结论:突变活化型的Ⅰ型磷酸酶抑制亚基1可诱导宫颈癌HeLa细胞G2/M期停滞,它与cyclin A和cyclin B1表达上调及cyclin B1降解滞后有关,而G2/M期停滞的维持与p53和p21表达上调有关。

PM2.5降尘诱导A549细胞G2/M期阻滞的机制研究

PM_(2.5)降尘作用于A549细胞后,MTT法检测细胞存活率,扫描电镜观察细胞形态,流式细胞术检测细胞周期改变,RT-PCR检测周期阻滞相关基因p53、p21、CDK1、c-myc和lncRNA H19的表达水平,Western-blot检测周期蛋白cyclin B1表达。通过转染H19 siRNA干扰H19的表达,RT-PCR检测其对p53、c-myc及CDK1表达的影响,以探讨PM2.5降尘诱导A549细胞周期阻滞的作用机制。结果显示,PM2.5降尘暴露可降低A549细胞存活率,随作用浓度及时间增加呈递减趋势,并可观察到细胞形态破坏,细胞膜表面吸附聚集大量粉尘颗粒。PM2.5作用于细胞24 h后,A549细胞增殖阻滞在G2/M期,周期阻滞相关基因p53、p21及H19表达增加,CDK1及cyclin B1表达降低。此外,转染H19 siRNA后成功干扰H19的表达,并调控CDK1表达进一步降低。综合以上结果,PM2.5降尘处理A549细胞后可通过激活p53及p21活性,抑制CDK1和cyclin B1表达水平,诱导G2/M期阻滞从而抑制细胞增殖。短期暴露于PM2.5后,lncRNA H19在染毒细胞中可能发挥特异性癌基因的作用,通过与p53及c-myc结合参与调控细胞周期,干扰H19低表达使细胞G2/M期阻滞更加明显。

细胞G2/M周期阻滞与肾间质纤维化

慢性肾脏病(CKD)是威胁人类公共健康的重大疾病之一,肾间质纤维化是各种CKD进展至终末期肾病的共同病理表现。然而肾间质纤维化的病理机制还有待阐明,临床也缺乏针对肾间质纤维化有效的治疗方法。越来越多研究表明,肾小管上皮细胞G2/M周期阻滞是肾间质纤维化发生发展中的一个重要事件。在多种肾损伤模型中,均发现肾小管上皮细胞G2/M周期阻滞和肾脏纤维化的因果关系,逆转细胞G2/M周期阻滞成为缓解肾脏纤维化的潜在靶点。此外,相关机制研究表明,包括丝裂原活化蛋白激酶(MAPK)、自噬等在内的诸多信号通路与细胞G2/M周期阻滞密切关联,共同影响肾间质纤维化的发生与进展。本文就细胞G2/M周期阻滞参与肾间质纤维化的最新研究作一综述,以期为CKD的临床诊治和新药研发提供思路。

G2/M细胞周期阻滞在急性肾损伤向慢性肾脏病转变中的作用研究进展

急性肾损伤(acute kidney injury,AKI)的发病率和病死率都很高。研究发现,AKI是慢性肾脏病(chronic kidney disease,CKD)发生的独立危险因素。氧化应激、内质网应激、巨噬细胞极化及肾小管细胞周期阻滞均参与了AKI向CKD进展的病理生理过程。越来越多的证据表明,肾小管上皮细胞周期阻滞可能在纤维化的发展中发挥重要作用。事实上,在肾损伤后的适应不良修复过程中,许多正在进行细胞分裂的肾小管细胞在细胞周期的G2/M期会延长一段时间。本文综述了ARI后的不适应修复,其主要机制是G2/M期阻滞及参与G2/M期阻滞调控的相关因子,导致进行性肾脏纤维化的发展。

Arsenic Trioxide Inhibits Proliferation in K562 Cells by Changing Cell Cycle and Survivin Expression

To study the mechanisms involved in the inhibition of chronic myeloid leukemic cells (K562) proliferation induced by arsenic trioxide (As 2O 3) and to explore the potential role of Survivin, an inhibitor of apoptosis protein, in the regulation of As 2O 3 induced cell apoptosis, K562 cells were cultured with As 2O 3 of different concentrations. Cells were collected for proliferation analysis by MTT assay. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. Expression of Survivin protein and mRNA were detected by flow cytometry and RT-PCR, respectively. Our results showed that As 2O 3 (2-10 μmol/L) inhibited K562 cells growth effectively, but it did not induce cells apoptosis significantly. The percentage of K562 cells at G 2/M phase increased in proportion to As 2O 3 concentrations, and the expression of Survivin mRNA and content of Survivin protein was up-regulated accordingly. It is concluded that As 2O 3 inhibited K562 cells growth by inducing cell cycle arrest mainly at G 2/M phase. Over-expression of Survivin gene and protein might be one of the possible mechanisms contributing to K562 cells' resistance to As 2O 3-induced apoptosis.

Far Infrared Ray Radiation Inhibits the Proliferation of A549, HSC3 and Sa3 Cancer Cells through Enhancing the Expression of ATF3 Gene

Far-infrared ray (FIR) is electromagnetic wave between 4 and 1000 μm. FIR causes heating, but how it affects cells is not well understood. In this study, we developed a culture incubator that can continuously irradiate cells with FIR and examined the effects of FIR on five human cancer cell lines, namely A431 (vulva), A549 (lung), HSC3 (tongue), MCF7 (breast) and Sa3 (gingiva). We found that FIR inhibits cell proliferation and induces cell hypertrophy without apoptosis in A549, HSC3 and Sa3 cells. Flow cytometry revealed that the inhibition of proliferation was due to G2/M arrest. Contrary, FIR did not inhibit cell proliferation and cause cell hypertrophy in A431 or MCF7 cells. Microarray analysis revealed that FIR suppressed the expression of cell proliferation-related and stress-responsive genes in FIR-sensitive cell lines (A549, HSC3 and Sa3). ATF3 in particular was identified as a key mediator of the FIR effect. Over-expression of ATF3 inhibited cell proliferation and knockdown of ATF3 mRNA using an antisense oligonucleotide suppressed FIR-induced growth arrest. These results indicate that a body temperature range of FIR radiation suppresses the proliferation of A549, HSC3, Sa3 cells and it appears that ATF3 play important roles in this effect.

Astragalus saponins induce apoptosis in human gastric adenocarcinoma cells via a caspase 3-dependent pathway

Objective Many Asian countries including China,Japan and Korea have very high incidence of gastric cancer,in which about 42% cases occur in China's Mainland.The precise targets and underlying mechanisms are not well understood.Our previous study revealed that Astragalus saponins(AST)showed promising effects on the suppression of the growth of HT-29 human colon cancer cells and tumor xenograft by inhibiting cell proliferation and promoting apoptosis.In the present study,we investigated the anti-carcinogenic effects of AST in AGS human gastric adenocarcinoma cells and attempted to elucidate the underlying mechanisms.Methods Growth inhibition of AGS cells was determined by using the MTT viability test.Involvement of different members of the apoptotic cascade and other growth-related factors was explored by assessment of their protein expression using Western blot analysis.Distribution of cells in different phases of the cell cycle was assessed by flow cytometry.Results Our data indicate that AST induced growth-inhibition and apoptosis in AGS cells by activating caspase 3 with subsequent poly(ADP-ribose)polymerase(PARP)cleavage.Cell cycle arrest at the G2/M phase had been observed in AST-treated AGS cells.The anti-proliferative effect of AST was associated with modulation of cyclin B1 and p21.We then demonstrate that AST could downregulate the expression of VEGF,of which interaction with its receptors is important for angiogenesis during tumor formation.Conclusions Our findings suggest that AST is an effective agent in gastric cancer treatment by inducing cell cycle arrest and apoptosis,of which anti-angiogenesis could be an alternative mode of action.

Research on cell cycle retardation, apoptosis and the expression of antioncogene p57^(Kip2) by radioactive rays in nasopharyngeal carcinoma cell line in vitro

Objective: To study cell cycle retardation, apoptosis and the expression of antioncogene p57kip2 by radioactive rays in nasopharyngeal carcinoma cells. Methods: Cell cycle retardation, apoptosis and cell survival rate induced by radioac- tive rays were tested by the methods of flow cytometry and MTT method. The expression of antioncogene p57kip2 was detected by immunohistochemistry and Western blot. Results: After irradiation, G1 phase had no obvious retardation, S phase showed transient delay. There was a positive correlation between irradiation dosage and retardation strength in G2/M phase (P < 0.01). Peak value appeared at 24 h after 12 Gy irradiation, then decreased. There was a positive correlation between apop- tosis incidence and irradiation dosage or after-irradiation time extention (P < 0.01). There was a negative correlation between cell survival rate and irradiation dosage or apoptosis incidence (P < 0.01). The expression of p57kip2 protein was up-regulated along with the prolongation of time and dosage after irradiation (P < 0.01). Conclusion: G2/M phase arrest, apoptosis and the up-regulation of the expression of p57kip2 protein all can reflect predict the radiosensitivity of nasopharyngeal carcinoma cells.

Genistein-induced Anticancer Effects on Acute Leukemia Cells Involve the Regulation of Wnt Signaling Pathway Through H4K20mel Rather Than DNA Demethylation

Objective:To investigate the effects and mechanisms of genistein on the gene expression in the Wnt pathway in acute leukemia(AL)cells.Methods:The expression of Wnt pathway genes and cell cycle-related genes were analyzed in two AL cell lines.Pyrophosphate sequencing was performed to determine the methylation degree.Then,the enrichment of H4K20mel and H3K9ac was determined using ChIP-qPCR.Flow cytometry was used to analyze the cell cycle.Results:The IC_(50) of genistein in the two AL cell lines was lower than that for the bone marrow mesenchymal stem cell line.Genistein upregulated H4K20mel,KMT5A and Wnt suppressor genes,including Wnt5a,and downregulated the downstream target genes of Wnt,such as c-myc and β-catenin.The methylation degree and H3K9ac enrichment in the Wnt5a promoter region remained unchanged.However,the enrichment of H4K20mel in the Wnt5a promoter and coding regions increased.In addition,genistein upregulated Phospho-cdc2,Mytl,Cyclin A,Cyclin E2,p21 and Phospho-histone H3,but downregulated Phospho-weel.Cell cycle arrest was induced in the G2/M phase.Conclusion:Genistein inhibits the activation of the Wnt pathway by promoting the expression of Wnt5a through the activation of KMT5A and enrichment of H4K20mel in the Wnt5a gene promoter and coding regions,rather than demethylation.Genistein also blocks the cell cycle in the G2/M phase.Therefore,genistein is a potential anti-leukemia drug.

Dual effect of Molt-4 cell line onset with roscovitine

Objective:To observe the effect of roscovitine(ROSC)as some Cyclin-dependent kinases(CDKs),inhibitor onset with the Molt-4 cell lines.Methods:DNA assay of single cells by flow cytometry was used to detect the effect of cell cycle arrest and Annexin-V/FITC assay was used to detect the effect of cell apoptosis when the Molt-4 cell lines cultured with different concentration ROSC in different time points.Results:It showed that ROSC exerted strong inhibitory effect on prolif- eration and cell cycle progression of Molt-4 cell lines,accumulation of G2/M cells arrested took place after onset with 10μm and 20μm ROSC more than 6 h;at the same time,the cell apoptosis of Molt-4 cells would be detected.According with the time and concentration increasing,the cell apoptosis rate would rise.Conclusion:It is concluded that Roscovitine(ROSC) as some Cyclin-dependent kinases(CDKs),inhibitor,has dual effects to Molt-4 cells,not only the effect of cell cycle arrest but also the effect of cell apoptosis.

电离辐射对Jurkat T细胞周期进程的影响

目的：探讨电离辐射诱导Jurkat T细胞损伤过程中细胞周期进程的变化规律。方法：采用流式细胞术（FCM）检测低剂量（0.075 Gy）和较大剂量（0.5、1.0、2.0、4.0及6.0 Gy）X射线照射后Jurkat T细胞周期进程变化的时间-效应关系和剂量-效应关系。结果：时间-效应关系研究发现，2.0 Gy X射线照射后JurkatT细胞相继发生S期延迟和G2期阻滞，S期细胞百分率于照射后立即增加（P〈0.001），而G2＋M期细胞百分率照射后8 h开始显著增加（P〈0.001）。剂量-效应关系研究发现，75 mGy低剂量X射线照射即可诱导JurkatT细胞发生S期延迟（P〈0.001）和G2期阻滞（P〈0.05）；0.5-6.0 Gy较大剂量X射线照射后，Jurkat T细胞发生S期延迟和G2期阻滞。与假照组相比较，G0/G1期细胞百分率显著降低（P〈0.001），在0.5-6.0 Gy内具有剂量依赖性，而S期和G2＋M期细胞百分率显著升高（P〈0.05或P〈0.001）。结论：X射线照射可以改变Jurkat T细胞周期进程，诱导其相继发生S期延迟和G2期阻滞，在0.5-6.0 Gy内具有剂量依赖性。

氯化两面针碱诱导人肝癌细胞SMMC-7721凋亡的研究

目的研究氯化两面针碱诱导人肝癌细胞SMMC-7721凋亡的作用。方法采用噻唑蓝(MTT)比色法检测人肝癌细胞SMMC-7721生长活力;Hoechst33258核染色,观察细胞形态学变化;流式细胞仪检测细胞周期及细胞凋亡率。结果氯化两面针碱作用于细胞后,在体外呈浓度、时间依赖性显著抑制SMMC-7721细胞的生长,作用24、48、72h的半数抑制浓度(IC50)分别为(19.5±1.8)、(3.8±0.2)、(2.8±0.1)mg/L;Hoechst33258染色后,可见核染色质凝集,凋亡细胞呈致密浓染,与对照组相比,氯化两面针碱处理后凋亡细胞比例增加;流式细胞仪检测到G2/M细胞比例增加,G0/G1、S期细胞比例下降。药物作用于SMMC-7721细胞后,随浓度增加细胞凋亡率增加。结论氯化两面针碱对SMMC-7721细胞有明显的生长抑制作用,可能与改变细胞周期并诱导细胞凋亡有关。

下调GINS2表达抑制HL60细胞周期调控因子

目的观察下调GINS2的表达后对人白血病细胞系HL60周期调控因子的变化并探讨其机制。方法脂质体介导并稳定转染干扰质粒的细胞为干扰组,转染阴性对照质粒的细胞为阴性对照组,只加入脂质体的细胞为空白对照组,未转染的HL60细胞为未处理组。集落形成实验测定细胞增殖;流式细胞术分析细胞周期;3H-TdR掺入实验检测细胞DNA合成;Western blot检测CDK1、cyclinB1等蛋白;RT-PCR检测ATM,CHK2,P53等mRNA水平;Western blot检测其蛋白水平。结果和其他3组相比,干扰组细胞G2期细胞数明显增加、DNA合成受阻、增殖减慢。与G2期相关周期调控蛋白CDK1,cyclinB1的表达随时间变化而明显降低。和其他3组相比,干扰组细胞ATM,CHK2,P53转录水平和翻译水平显著上调。结论下调GINS2表达后可抑制HL60细胞DNA复制并影响其G期进程,机制可能与ATM,CHK2,P53等基因相关。

Gadd45介导抑癌基因BRCA1诱导的G_2/M期阻滞

背景与目的:目前已经肯定,抑癌基因BRCA1是细胞周期监测点调控的重要因子,但BRCA1在细胞周期阻滞中的作用机制尚不完全清楚。本研究的目的是探讨Gadd45在BRCA1诱导的细胞周期阻滞中所起的作用。方法:应用转染、流式细胞仪细胞筛选(分选)、Westernblot检测分析BRCA1诱导Gadd45的表达;利用CAT酶活性测定的方法检测外源BRCA1对Gadd45启动子所起作用;以流式细胞周期分析方法检测反义Gadd45转染对BRCA1诱导的细胞G2/M期阻滞的影响;采用细胞生长集落形成分析反义Gadd45转染HeLa、HCT116细胞在BRCA1诱导的细胞生长抑制过程所起的作用。结果:外源转染BRCA1可诱导Gadd45蛋白的表达;BRCA1激活Gadd45启动子的转录;反义Gadd45可显著阻遏BRCA1诱导细胞G2/M期阻滞;反义Gadd45转染可明显降低BRCA1对HeLa、HCT116细胞集落形成的抑制作用。结论:Gadd45作为BRCA1的下游调控基因,在BRCA1诱导的细胞G2/M期阻滞过程和生长抑制中起介导作用。

葫芦素E通过诱导G_2/M周期阻滞抑制人肝癌细胞增殖

目的研究葫芦素E(cucurbitacin E,CuE)体外对人肝癌BEL7402和HepG2细胞的增殖抑制作用及机制。方法MTT法检测不同浓度CuE体外对BEL7402和HepG2细胞的增殖抑制作用;流式细胞仪检测CuE对细胞周期分布的影响;Western blot法检测CuE对细胞周期调节蛋白cy-clinB1、Cdc25C、Cdk1及p21表达的影响。结果CuE作用72 h可剂量依赖性地抑制BEL7402和HepG2细胞增殖;CuE(100 nmo.lL-1)作用12、24 h后可使BEL7402和HepG2细胞周期阻滞于G2/M期,并可下调Cdk1蛋白的表达,上调p21蛋白的表达。结论CuE体外可抑制人肝癌BEL7402和HepG2细胞的增殖,其增殖抑制作用与诱导G2/M周期阻滞有关。