Ethanol extract of Kalopanax septemlobus leaf inhibits HepG2 human hepatocellular carcinoma cell proliferation via inducing cell cycle arrest at G_1 phase

Objective:To investigate the effects of an ethanol extract of Kalopanax septemlobus(Thunb.)Koidz.leaf(EEKS) on cell proliferation in human hepatocellular carcinoma cells and its mechanisms of action.Methods:Cells were treated with EEKS and subsequently analyzed for cell proliferation and flow cytometry analysis.Expressions of cell cycle regulators were determined by reverse transcriptase polymerase chain reaction analysis and Western blotting,and activation of eyclin-associaled kinases studied using kinase assays.Results:The EEKS suppressed cell proliferation in both HepG2 and Hep3 B cells,but showed a more sensitive anli-proliferative activity in HepG2 cells.Flow cytometry analysis revealed an association between the growth inhibitory effect of EEKS and with G_1 phase cell cycle arrest in HepG2 cells,along with the dephosphorylation of retinoblastoma protein(pRB) and enhanced binding of pRB with the E2 F transcription factor family proteins.Treatment with EEKS also increased the expression of cyclin-dependent kinase(CDK) inhibitors,such as p21WAF1/CIP1 and p27KIP1.without any noticeable changes in G_1 cyclins and CDKs(except for a slight decrease in CDK4).Treatment of HepG2 cells with EEKS also increased the binding of p21 and p27 with CDK4 and CDK6.which was paralleled by a marked decrease in the cyclin D- and cyclin E-associated kinase activities.Conclusions:Overall,our findings suggest that EEKS may be an effective treatment for liver cancer through suppression of cancer cell proliferation via G_1,cell cycle arrest Further studies arc required to identify the active compounds in EEKS.

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.

Paris chinensis dioscin induces G2/M cell cycle arrest and apoptosis in human gastric cancer SGC-7901 cells

AIM:To investigate the anti-tumor effects of Paris chinensis dioscin(PCD)and mechanisms regarding cell cycle regulation and apoptosis in human gastric cancer SGC-7901 cells.METHODS:Cell viability was analyzed by the 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay.Cell apoptosis was evaluated by flow cytometry and laser scanning confocal microscope(LSCM)using Annexin-V/propidium iodide(PI)staining,and the cell cycle was evaluated using PI staining with flow cytom-etry.Intracellular calcium ions were detected under fluorescence microscope.The expression of cell cycle and apoptosis-related proteins cyclin B1,CDK1,cytochrome C and caspase-3 was measured by immunohistochemical staining.RESULTS:PCD had an anti-proliferation effect on human gastric cancer SGC-7901 cells in a dose-and time-de-pendent manner.After treatment of SGC-7901 cells with PCD,apoptosis appeared in SGC-7901 cells.Morpho-logical changes typical of apoptosis were also observed with LSCM by Annexin V/PI staining,and the cell number of the G0/G1 phase was decreased,while the number of cells in the G2/M phase was increased.Cell cycle-related proteins,such as cyclin B1 and CDK1,were all down-regulated,but caspase-3 and cytochrome C were up-regulated.Moreover,intracellular calcium accumulation occurred in PCD-treated cells.CONCLUSION:G2/M phase arrest and apoptosis induced by PCD are associated with the inhibition of CDK-activating kinase activity and the activation of Ca2+-related mitochondrion pathway in SGC-7901 cells.

Mechanisms involved in ceramide-induced cell cycle arrest in human hepatocarcinoma cells

AIM： To investigate the effect of ceramide on the cell cycle in human hepatocarcinoma Bel7402 cells. Possible molecular mechanisms were explored. METHODS： [3- （4, 5）-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide （MTT） assay, plasmid transfection, reporter assay, FACS and Western blotting analyses were employed to investigate the effect and the related molecular mechanisms of C2-ceramide on the cell cycle of Bel7402 cells. RESULTS： C2-ceramide was found to inhibit the growth of Bel7402 cells by indudng cell cycle arrest. During the process, the expression of p21 protein increased, while that of cyclinD1, phospho-ERKl/2 and c-myc decreased. Furthermore, the level of CDK7 was downregulated, while the transcriptional activity of PPARy was upregulated. Addition of GW9662, which is a PPARy specific antagonist, could reserve the modulation action on CDK7. CONCLUSION： Our results support the hypothesis that cell cycle arrest induced by C2-ceramide may be mediated via accumulation of p21 and reduction of cyclinD1 and CDK7, at least partly, through PPARy activation. The ERK signaling pathway was involved in this process.

Chaga mushroom (Inonotus obliquus) induces G0/G1 arrest and apoptosis in human hepatoma HepG2 cells

AIM: To investigate the anti-proliferative and apoptotic effects of Chaga mushroom (Inonotus obliquus) water extract on human hepatoma cell lines,HepG2 and Hep3B cells. METHODS: The cytotoxicity of Chaga extract was screened by 3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological observation,flow cytometry analysis,Western blot were employed to elucidate the cytotoxic mechanism of Chaga extract. RESULTS: HepG2 cells were more sensitive to Chaga extract than Hep3B cells,as demonstrated by markedly reduced cell viability. Chaga extract inhibited the cell growth in a dose-dependent manner,which was accompanied with G0/G1-phase arrest and apoptotic cell death. In addition,G0/G1 arrest in the cell cycle was closely associated with down-regulation of p53,pRb,p27,cyclins D1,D2,E,cyclin-dependent kinase (Cdk) 2,Cdk4,and Cdk6 expression. CONCLUSION: Chaga mushroom may provide a new therapeutic option,as a potential anticancer agent,in the treatment of hepatoma.

Influence of CDK1 and CDK2 siRNA interference on tumor cell cycle and cell apoptosis

Objective： We investigated the influence of CDK1 and CDK2 expression inhibited by cotransfection of CDK1 and CDK2 siRNA on cell cycle and apoptosis, explored the exact role of cell cycle master regulator in tumor cell apoptosis process. Methods： The siRNA targeting the CDK1 and CDK2 genes were synthesized and simultaneously cotransfected into Hela cells by lipofectamine 2000.48 or 60 h after the cotransfection, CDK1 and CDK2 protein expressions were examined by Western blot. Cell cycle distribution was analyzed by flow cytometry. Cell apoptosis was detected by the Annexin V/PI method. The changes of the transfected cell morphological under a microscope after Wright-Giemsa Staining were studied. Results： CDK1 and CDK2 protein expression was decreased at 48 or 60 h after cotransfection. The accumulation of the G2/M and S phase population in cell cycle of the cotransfected cells at 48 or 60 h after transfection was enhanced obviously compared with control. The ratio of apoptotic cell of cotransfected cells at 48 or 60 h after transfection was increased significantly compared with control. More binucleate or multinucleate ceJls among cotransfected cells were observed under the microscope. Conclusion： The decreased expression of CDK1 and CDK2 by cotransfection of CDK1 and CDK2 siRNA not only leads to tumor cell cycle arrest in S phase and G2/M phase, but also induces tumor cell apoptosis.

Gambogic acid induces mitochondria-dependent apoptosis by modulation of Bcl-2 and Bax in mantle cell lymphoma JeKo-1 cells

Objective： To study the mechanisms in gambogic acid （GA） -induced JeKo-1 human Mantle Cell Lymphoma cell apoptosis in vitro. Methods： The proliferation of GA-treated JeKo-1 cells was measured by CCK-8 assay and Ki-67 immunocytochemical detection. Apopt0sis, cell cycle and mitochondrial membrane potential were measured by flow cytometric analysis. Caspase-3, -8 and -9 were detected by colorimetric assay. Bcl-2 and Bax were analyzed by Western blotting. Results： GA inhibited cell growth in a time- and dose- dependent manner. GA induces apoptosis in JeKo- 1 cells but not in normal bone marrow cells, which was involved in reducing the membrane potential of mitochondria, activating caspases-3, -8 and -9 and decreasing the ratio of Bd-2 and Bax without cell cycle arresting. Conclusions： GA induced apoptosis in human MCL JeKo-1 cells by regulating Bcl-2/Bax and activating caspase-3, -8 and -9 via mitochondrial pathway without affecting cell cycle.

Senescence-like changes induced by expression of p21^(Waf1/Cipl)in NIH3T3 cell line

P21Waf1/Cip1 is a potent cyclin-dependent kinase inhibitor. As a downstream mediator of p53, p21Waf1/Cip1 involves in cell cycle arrest, differentiation and apoptosis. Previous studies in human cells provided evidence for a link between p21Waf1/Cip1 and cellular senescence. While in murine cells, the role of p21Waf1/Cip1 is indefinite. We explored this issue using NIH3T3 cells with inducible p21Waf1/Cip1 expression. Induction of p21Waf1/Cip1 triggered G1 growth arrest, and NIH3T3-p21 cells exhibited morphologic features, such as enlarged and flattened cellular shape, specific to the senescence phenotype. We also showed that p21Waf1/Cip1-transduced NIH3T3 cells expressed β-galactosidase activity at pH 6.0, which is known to be a marker of senescence. Our results suggest that p21Waf1/Cip1 can also induce senescence-like changes in murine cells.

Senescence—like changes induced by expression of p21^Waf1／Cip1 in NIH3T3 cell line

P21Waf1/Cip1 is a potent cyclin-dependent kinase inhibitor. As a downstream mediator of p53, p21Waf1/Cip1 involves in cell cycle arrest, differentiation and apoptosis. Previous studies in human cells provided evidence for a link between p21Waf1/Cip1 and cellular senescence. While in murine cells, the role of p21Waf1/Cip1 is indefinite. We explored this issue using NIH3T3 cells with inducible p21Waf1/Cip1 expression. Induction of p21Waf1/Cip1 triggered G1 growth arrest, and NIH3T3-p21 cells exhibited morphologic features, such as enlarged and flattened cellular shape, specific to the senescence phenotype. We also showed that p21Waf1/Cip1-transduced NIH3T3 cells expressed β-galactosidase activity at pH 6.0, which is known to be a marker of senescence. Our results suggest that p21Waf1/Cip1 can also induce senescence-like changes in murine cells.

Epigenetic Enabled Normal Human Cells, Lead to <i>First Cell</i>’s Unique Division System, Driving Tumorigenesis Evolution

Normal cells must become cancer-enabling before anything else occurs, according to latest literature. The goal in this mini-review is to demonstrate special tetraploidy in the enabling process. This we have shown from genomic damage, DDR (DNA Damage Response) activity with skip of mitosis leading to diploid G2 cells at the G1 border in need of chromatin repair for continued cell cycling to the special tetraploid division system. In several studies specific methylation transferase genes were activated in normal human cells in tissue fields, containing different cell growth stages of the cancerous process. Histology studies, in addition to molecular chemistry for identification of oncogenic mutational change, were a welcome change (see below). In a study on melanoma origin, DDR also showed arrested diploid cells regaining cycling from methylation transferase activity with causation of 2n melanocytes transforming to 4n melanoblasts, giving rise to epigenetic tumorigenesis enabled First Cells. Such First Cells were from Barrett’s esophagus shown to have inherited the unique division system from 4n diplochromosomal cells, first described in mouse ascites cancer cells (below). We discovered that the large nucleus prior to chromosomal division turned 90° relative to the cytoskeleton axis, and divided genome reductive to diploid, First Cells, in a perpendicular orientation to the surrounding normal cells they had originated from. This unique division system was herein shown to occur at metastasis stage, implying activity throughout the cancerous evolution. Another study showed 4-chromatid tetraploidy in development to B-cell lymphoma, and that such cancer cells also proliferated with participation of this unusual division system. Such participation has long been known from Bloom’s inherited syndrome with repair chiasmas between the four chromatids, also an in vitro observation by us. Our cytogenetic approach also revealed that they believed mitotic division in cancer cells is wrong because such cell divisions were found to be from an adaptation between amitosis and mitosis, called amitotic-mitosis. Amitosis means division without centrosomes, which has long been known from oral cancer cells, in that MOTCs (microtubule organizing center) were lacking centrioles. This observation calls for re-introduction of karyotype and cell division studies in cancer cell proliferation. It has high probability of contributing novel approaches to cancer control from screening of drugs against the amitotic-mitotic division apparatus.

1-硝基芘通过线粒体损伤致卵巢颗粒细胞功能障碍

目的探讨1-硝基芘(1-nitropyrene,1-NP)通过诱导线粒体损伤对人卵巢颗粒细胞KGN的增殖、周期进展及性激素合成的影响。方法采用不同浓度(0.625、1.25、2.5、5、10μmol/L)1-NP染毒KGN细胞48 h,EdU掺入法检测细胞增殖,流式细胞仪检测细胞周期,ELISA检测细胞培养上清中雌二醇及孕烯醇酮浓度,DCFH-DA探针检测细胞活性氧(reactive oxygen species,ROS)水平,MitoSOX探针检测线粒体超氧化物(mitochondrial superoxides,MitoSOX)水平,JC-1探针检测线粒体膜电位,ATP试剂盒检测细胞内ATP含量,Western blot检测细胞增殖、周期进展、DNA损伤反应以及性激素合成相关蛋白的表达。采用线粒体抗氧化剂IDE、1-NP单独和联合处理细胞,再次检测上述指标。结果不同浓度1-NP染毒后KGN细胞增殖显著降低(P<0.05)。2.5、5、10μmol/L的1-NP处理细胞后,细胞增殖标志物PCNA蛋白表达显著降低,5、10μmol/L的1-NP处理后G2/M期细胞比例显著升高(P<0.05)。1-NP(10μmol/L)处理3 h即可诱导γ-H2AX表达增加(P<0.01);不同浓度1-NP处理后,DNA损伤反应通路蛋白p-ATM、p53和p21cip1表达明显升高(P<0.05),G2/M期阻滞相关蛋白CDK-1和CyclinB1表达明显降低(P<0.05)。此外,1-NP处理后KGN细胞的雌二醇、孕烯醇酮浓度显著下降(P<0.05),性激素合成相关蛋白CYP19、CYP11A1的表达也受到抑制(P<0.05)。线粒体及氧化应激相关指标检测结果显示,1-NP导致KGN细胞中ROS、MitoSOX水平显著升高,线粒体膜电位和ATP水平呈剂量依赖性下降。与10μmol/L 1-NP单独染毒组相比,IDE与1-NP联合处理组G2/M期细胞比例显著下降,雌二醇、孕烯醇酮水平出现一定程度升高,DNA损伤反应、细胞周期进展以及性激素合成相关蛋白的表达也出现明显恢复。同时,IDE与1-NP联合处理显著改善1-NP诱导的线粒体损伤,包括降低细胞ROS和MitoSOX水平,提高线粒体膜电位和ATP水平。结论1-NP可诱导线粒体损伤,造成卵巢颗粒细胞KGN的增殖抑制、周期阻滞、性激素合成障碍,而提高线粒体功能则能部分缓解1-NP诱导的KGN细胞功能障碍。

Liproxstatin-1对K562白血病细胞的增殖抑制作用及其机制研究

目的:研究Liproxstatin-1(Lip-1)对K562白血病细胞株的抑制作用。方法:采用CCK-8法检测不同浓度Lip-1处理前后的细胞活力。将未经任何处理的K562细胞作为对照组,10μmol/L Lip-1处理24 h的K562细胞作为低浓度组,20μmol/L Lip-1处理24 h的K562细胞作为高浓度组。用二代测序法分析各组转录组表达差异。分别采用实时荧光定量PCR(RT-qPCR)、Western blotting法检测细胞周期蛋白依赖性激酶抑制剂-1A(CDKN1A)、溶质载体家族7成员11(SLC7A11)基因及蛋白表达,流式细胞术检测细胞周期时相,微量法测定细胞内谷氨酸含量。将K562细胞在含或不含谷氨酰胺培养基中培养,用细胞计数法检测细胞倍增时间(DT)变化。结果:Lip-1浓度依赖性抑制K562白血病细胞增殖。与对照组相比,低、高浓度组CDKN1A、SLC7A11基因及蛋白表达水平增高(P<0.05),高浓度组细胞内谷氨酸含量下降(P<0.05),低浓度组发生G1/S阻滞,而高浓度组同时存在G1/S和G2/M阻滞。K562细胞在不含谷氨酰胺培养基培养时细胞的DT较含谷氨酰胺组增高(P<0.05)。结论:Lip-1可抑制K562白血病细胞增殖,其机制可能与SLC7A11表达增高引起的谷氨酸剥夺及CDKN1A表达增高引起的细胞周期阻滞有关。

Caveolin-1 Re-Expression Reverses G_0/G_1 Arrest in Caveolin-1 Knockout Mesangial Cells

Flow cytometry,BrdU incorporation,and western blotting were used to investigate whether caveolin-1（Cav-1） is involved in cell cycle progression of renal glomerular mesangial cells.Wide type mesangial cells re-entered the cell cycle after 22 h incubation with 20% fetal bovine serum（FBS） and Cav-1 knockout cells remained in G0/G1 phase after 48 h,which indicated that Cav-1 knockout mesangial cells were G0/G1 arrest.The protein level of cyclin D1 significantly increased after incubation with 20% FBS for 6 h in wide type mesangial cells,and 12 h in Cav-1 knockout cells.It suggested that cyclin D1 upregulation was delayed in knockout mesangial cells.Cav-1 re-expression in Cav-1 knockout mesangial cells increased the ratio of S phase from 4.8% to 15.26%,and decreased the ratio of G0/G1 phase from 90.96% to 77.84%,which implied that Cav-1 re-expression can reverse cell cycle arrest.It concludes that Cav-1 may promote the proliferation of mesangial cells.

Combined inhibition of HDAC and DNMT1 induces p85α/MEKmediated cell cycle arrest by dual target inhibitor 208 in U937 cells

Multiple histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) have been developed for cancer therapy. However, the research on their mechanisms of action is not sophisticated enough. In this study, we reported a dual HDAC and DNMT inhibitor 208 and found it induced G1 cell cycle arrest and apoptosis in U937 cells. Proteome and bioinformatic analyses revealed that the combined inhibition of DNMT1 and HDAC by 208 affected the expression of a series of proteins involved in many biological processes. We observed that several proteins associated with G1 cell cycle arrest and apoptosis were down regulated after 208 treatment, including p85α, MEK, and CDK4, suggesting that 208 induces cell cycle arrest and apoptosis through the p85α/MEK-mediated pathway in U937 cells. Moreover, biological function analysis showed that the combined epigenetic inhibition influenced various processes, including the synthesis and processing of RNA, translation, protein transport, and DNA repair. These findings provide novel insight into the potential mechanisms of multifunctional epigenetic inhibitors, which supports their further improvement and development.

不同剂量X射线全身照射对小鼠骨髓细胞周期进程的影响

本文采用流式细胞术研究了不同剂量 X射线全身照射后小鼠骨髓细胞周期进程的变化。结果表明 ,0 .0 75 Gy X射线全身照射后 2～ 72 h骨髓细胞周期各时相细胞百分数未发生明显变化 ;2 .0 Gy全身照射后 4 h骨髓细胞便开始出现明显的 G2 阻滞 ,12 h同时出现 G1、G2 阻滞 ,而后很快恢复到假照水平。不同剂量 (0 .0 5 Gy～ 6 .0 Gy)全身照射后 12 h量效结果表明 ,低剂量范围内 (0 .0 5～ 0 .2 Gy)骨髓细胞周期各时相细胞百分数未发生明显变化 ;较大剂量范围内 (0 .5 Gy～ 6 .0 Gy)照射后出现明显的G1、G2 阻滞 ,S期细胞百分数减少。提示低剂量全身照射后骨髓细胞周期进程未检测出变化 ;而较大剂量全身照射后 ,骨髓细胞出现 DNA合成抑制 ,G1和 G2

双氢青蒿素诱导肺癌SPC-A-1细胞周期阻滞的研究

目的:探讨双氢青蒿素对肺癌SPC-A-1细胞周期的阻滞作用及介导其周期阻滞的机制。方法:双氢青蒿素处理SPC-A-1细胞,PCR及免疫印迹检测生存素表达情况,基因转染建立生存素高表达SPC-A-1细胞,采用流式细胞术检测细胞周期变化。结果:双氢青蒿素可以诱导SPC-A-1细胞G2/M期周期阻滞,生存素表达下调,生存素高表达拮抗双氢青蒿素诱导的SPC-A-1细胞G2/M期周期阻滞。结论:生存素参与介导双氢青蒿素诱导的SPC-A-1细胞G2/M周期阻滞。

Peroxiredoxin 1基因沉默对肝癌细胞HepG2和SMMC-7721放射增敏的研究

目的探讨Peroxiredoxin（Prx）1基因的小分子干扰RNA（si RNA）对人肝癌细胞系HepG2和SMMC-7721的放射增敏作用及机制。方法通过逆转录PCR方法研究Prx家族（Prx1~6）在人肝癌细胞HepG2和SMMC-7721中的mRNA表达谱;使用si RNA敲低HepG2和SMMC-7721细胞高表达的Prx1亚型为Prx1 si RNA转染组,另设空白对照组、阴性对照组（Prx1si Neg）,分别经不同剂量X射线照射后,克隆形成法检测各组细胞的增殖情况,流式细胞仪测定细胞内活性氧水平、细胞周期及凋亡情况。结果 HepG2和SMMC-7721细胞均高表达Prx1、Prx3和Prx5。与对照组相比,两种细胞Prx1 si RNA转染组在8 Gy X线照射后其剂量生存曲线明显左移,照射12 h后细胞周期出现G2-M阻滞,24 h后细胞凋亡率及1 h后细胞内ROS水平明显升高（P〈0.05）。Prx1 si RNA转染组放射增敏比在1.38~1.45之间。结论小分子干扰RNA对人肝癌HepG2和SMMC-7721细胞有明显的放射增敏作用,其机制可能与细胞周期阻滞及细胞内活性氧水平升高有关。

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。

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。

生长抑制因子1剪接变异体调控p53信号通路诱导肝癌细胞凋亡

目的探讨生长抑制因子(ING1)调控p53信号通路诱导肝癌细胞凋亡的途径。方法通过脂质体转染的方法在体外培养的肝癌细胞株HepG2中过表达ING1基因3种剪接变异体,采用流式细胞仪检测各实验组细胞凋亡率和细胞周期变化,实时荧光定量逆转录聚合酶链式反应(RT-PCR)和Western blot法检测ING1、p53及其下游信号基因bcl-2、bax、p21waf1、mdm2、p14arfmRNA和蛋白表达情况,荧光素酶双标报道基因检测下游p21waf1启动子活性,Western blot检测野生型p53蛋白半衰期变化,使用免疫共沉淀法(IP)观察ING1剪接体与mdm2、p14arf蛋白间的结合情况。结果 HepG2细胞转染过表达ING1不同剪接变异体,pcDNA3-ING1b[(24.36±0.97)%]和pcDNA3-ING1c[(27.33±1.12)%]组细胞凋亡率显著高于空载体组[(8.22%±0.86)%](P<0.01),而pcDNA3-ING1a组细胞凋亡率[(8.90±1.03)%]与空载体组比较差异无统计学意义(P>0.05)。与空载体组比较,pcDNA3-ING1b和pcDNA3-ING1c组均出现G0/G1期阻滞(P<0.05);而pcDNA3-ING1a组各细胞周期的比例与空载体组比较差异无统计学意义(P>0.05)。RT-PCR及Western blot法结果显示过表达ING1b或ING1c使HepG2细胞内源性bax、p21waf1、p14arfmRNA及蛋白表达量明显增高(P<0.01);内源性bcl-2、mdm2 mRNA及蛋白表达量明显降低(P<0.01);过表达ING1a的HepG2细胞bax、bcl-2、p21waf1、mdm2、p14arfmRNA及蛋白表达与空载体组比较差异无统计学意义(P>0.05)。ING1b和ING1c增强p21waf1启动子活性,延长野生型p53蛋白的半衰期,促进p53蛋白乙酰化,并且与p53反馈调节环路基因mdm2和p14arf结合,维持p53蛋白的稳定性和促进p53蛋白的活性。结论 ING1剪接变异体通过与p53负反馈调节基因mdm2竞争性结合p53蛋白,延长野生型p53蛋白半衰期,并促进p53蛋白乙酰化,增强p53蛋白下游基因bax、p21waf1、p14arf表达,抑制bcl-2、mdm2基因表达,促进肝癌细胞凋亡。