Effects of allitridi on cell cycle arrest of human gastric cancer cells

AIM: To determine the effect of allitridi on cell cycle of human gastric cancer (HGC) cell lines MGC803 and SGC7901 and its possible mechanism. METHODS: Trypan blue dye exclusion was used to evaluate the proliferation, inhibition of cells and damages of these cells were detected with electron microscope. Flow cytometry and cell mitotic index were used to analyze the change of cell cycle, immunohistochemistry, and RTPCR was used to examine expression of the p21~(WAF1) gene. RESULTS: MGC803 cell growth was inhibited by allitridi with 24 h IC_(50) being 6.4 μg/mL. SGC7901 cell growth was also inhibited by allitridi with 24 h IC_(50) being 7.3 μg/mL After being treated with allitridi at the concentration of 12 μg/mL for 24 h, cells were found to have direct cytotoxic effects, including broken cellular membrane, swollen and vesiculated mitochondria and rough endoplasmic reticula, and mass lipid droplet. When cells were treated with allitridi at the concentration of 3, 6, and 9 μg/mL for 24 h, the percentage of G_0/G_1 phase cells was decreased and that of G_2/M phase cells was significantly increased (P=0.002) compared with those in the group. When cells were treated with allitridi at the concentration of 6 μg/mL, cell mitotic index was much higher (P=0.003) than that of control group, indicating that allitridi could cause gastric cancer cell arrest in M phase. Besides, the expression levels of p21~(WAF1)gene of MGC803 cells and p21~(WAF1) gene of SGC7901 cells were remarkably upregulated after treatment. CONCLUSION: Allitridi can cause gastric cancer cell arrest in M phase, and this may be one of the mechanisms for inhibiting cell proliferation. Effect of allitridi on cells in M phase may be associated with the upregulation of p21~(WAF1) genes. This study provides experimental data for clinical use of allitridi in the treatment of gastric carcinoma.     

Diallyl disulfide-induced G2／M arrest of human gastric cancer MGC803 cells involves activation of p38 MAP kinase pathways

AIM: To determine the role of p38 MAP kinase signal transduction pathways in diallyl disulfide (DADS)-induced G2/M arrest in human gastric cancer MGC803 cells. METHODS: MGC803 cell growth inhibition was measured by MTT assay. Phase distribution of cell cycle was analyzed by flow cytometry. Expression of Cdc25C, p38, phosphorylation of p38 (pp38) were determined by Western blotting. RESULTS: MTT assay showed that SB203580, a specific p38 MAPK inhibitor blocked DADS-induced growth inhibition. Flow cytometry analysis revealed that treatment of MGC803 cells with 30 mg/L DADS increased the percentage of cells in the G2/M phase from 9.3% to 39.4% (P<0.05), whereas inhibition of p38 activity by SB203580 abolished induction of G2/M arrest by DADS. Western blotting showed that phosphorylation of p38 was increased 3.52-fold following treatment of MGC803 cells with 30 mg/L DADS for 20 min (P<0.05), whereas Cdc25C was decreased 68% following treatment of MGC803 cells with 30 mg/L DADS for 24 h (P<0.05). Decreased Cdc25C protein expression by DADS was attenuated by SB203580 (P<0.05). CONCLUSION: DADS-induced G2/M arrest of MGC803 cells involves activation of p38 MAP kinase pathways. Decreased Cdc25C protein expression by p38 MAPK played a crucial role in G2/M arrest after treatment with DADS.     

PI3K/Akt抑制剂LY294002对胃癌细胞化疗增敏作用的探讨

目的 探讨PI3K/Akt特异性抑制剂LY294002与化疗药物5-Fu及奥沙利铂联合使用对3种胃癌细胞系(MGC803、BGC823和SGC7901)化疗效果的影响.方法 将PI3K/Akt特异性抑制剂LY294002联合化疗药物5-Fu及奥沙利铂作用于3种胃癌细胞系,MTT法检测单独使用5-Fu、奥沙利铂及联合LY294002对体外培养的3种胃癌细胞系的增殖抑制作用,流式细胞术检测细胞凋亡.结果 联合LY294002作用后,5-Fu、奥沙利铂对3种胃癌细胞系的增殖抑制作用明显增强(P<0.05),且凋亡率显著提高(P<0.05).结论结果 LY294002能有效提高化疗药物5-Fu、奥沙利铂体外对胃癌细胞的增殖抑制作用,抑制PI3K/Akt信号转导通路可显著提高胃癌的化疗疗效.     

Alisol B acetate induces apoptosis of SGC7901 cells via mitochondrial and phosphatidylinositol 3-kinases/Akt signaling pathways

AIM： To examine the effect of alisol B acetate on the growth of human gastric cancer cell line SGC7901 and its possible mechanism of action.
METHODS： The cytotoxic effect of alisol B acetate on SGC7901 cells was measured by 3-（4,5-dimethylthiazol- 2-yl）-2,5-diphenyltetrazolium bromide （MI-I-） assay. Phase-contrast and electron microscopy were used to observe the morphological changes. Cell cycle and mitochondrial transmembrane potential （A~Pm） were determined by flow cytometry. Western blotting was used to detect the expression of apoptosis-regulated gene Bcl-2, Bax, Apaf-1, caspase-3, caspase-9, Akt, P-Akt and phosphatidylinositol 3-kinases （PI3K）.
RESULTS： Alisol B acetate inhibited the proliferation of SGC7901 cell line in a time- and dose-dependent manner. PI staining showed that alisol B acetate can change the cell cycle distribution of SGC7901, increase the proportion of cells in G0-G1 phase and decrease the proportion of S phase cells and G2-M phase cells. Alisol B acetate at a concentration of 30 pmol/L induced apoptosis after 24, 48 and 72 h incubation, with occurrence rates of apoptotic cells of 4.36%, 14.42% and 21.16%, respectively. Phase-contrast and electron microscopy revealed that the nuclear fragmentation and chromosomal condensed, cells shrank and attachment loss appeared in the SGC7901 treated with alisol B acetate. Apoptosis of SGC7901 cells was associated with cell cycle arrest, caspase-3 and caspase-9 activation, loss of mitochondrial membrane potential and up-regulation of the ratio of Bax/Bcl-2 and inhibition of the PI3K/Akt.
CONCLUSION： Alisol B acetate exhibits an antiproliferative effect in SGC7901 cells by inducing apoptosis. Apoptosis of SGC7901 cells involves mitochondria-caspase and PI3K/Akt dependent pathways.     

血管内皮生长因子小干扰核糖核酸联合双自杀基因抗胃癌作用的体外研究

目的 探讨联合应用靶向血管内皮生长因子(VEGF)小干扰RNA(siRNA)与双自杀基因yCDglyTK对人胃癌细胞的体外杀伤作用。方法 以磷酸钙纳米颗粒为载体介导空白质粒pcDNA3.1（-）null(空白质粒组)、靶向VEGF的干扰质粒pGenesil-shVEGF(干扰质粒组)、双自杀基因质粒pcDNA3.1（-）CV-yCDglyTK(双自杀基因组)及联合基因质粒pcDNA3.1（-）shVEGF-yCDglyTK（联合基因组）转染胃癌SGC7901细胞,未转染的胃癌细胞为空白对照组,经G418筛选稳定转染的胃癌细胞株,采用RT-PCR和免疫印迹法验证目的基因表达。给予前体药物5-氟胞嘧啶(5-FC)后,通过四甲基偶氮唑盐(MTT)生长曲线、旁观者效应实验、Hoechst 33258染色及流式细胞术,观察各组细胞的生物学特性变化、凋亡细胞形态及凋亡率。采用SPSS 13.0统计学软件进行数据处理分析,组间多重比较采用LSD检验。结果成功建立4种转染不同质粒的胃癌细胞株,联合基因组及双自杀基因组均可检测到双自杀基因yCDglyTK的表达。MTT生长曲线显示5-FC作用24 h后,与空白对照组和空白质粒组相比,干扰质粒组、双自杀基因组及联合基因组吸光度值明显降低(P＜0.01)。当稳定转染联合基因的SGC7901细胞占60％、80％和100％时,细胞相对存活率分别为13.09％±2.40％、9.74％±2.83％及5.68％±1.03％。荧光显微镜下见双自杀基因组及联合基因组大量细胞呈现凋亡形态改变。流式细胞检测结果示干扰质粒组、双自杀基因组以及联合基因组的凋亡率分别为16.40％±4.68％、57.63％±4.96％及69.07％±4.69％,与空白对照组相比,差异有统计学意义(P＜0.01)。结论采用靶向VEGF siRNA与双自杀基因联合治疗可有效杀伤胃癌SGC7901细胞,诱导凋亡是其杀伤瘤细胞的重要机制之一。     

钙周期素结合蛋白的细胞周期依赖性转位现象

目的研究钙周期素结合蛋白（CacyBP／SIP）在胃癌细胞SGC7901中亚细胞定位与细胞周期的关系。方法利用双胸腺嘧啶脱氧核苷（胸苷）阻滞法将胃癌细胞SGC790l进行细胞周期同步化,流式细胞术检测细胞周期同步化效果。免疫荧光染色法观察CacyBP／SIP在不同时期的亚细胞定位。蛋白质印迹法检测CacyBP／SIP总蛋白及核蛋白在不同时期的表达水平。结果采用双胸苷阻滞法使SGC7901细胞阻滞于G,／s期,撤药后培养4h,细胞进入S期。大多数细胞在8～12h时进入G2／M期,16h又重新进入G1期。免疫荧光染色发现,在G1和S期时,CacyBP／SIP主要分布在细胞浆中,而在以G2期为主的细胞中,CacyBP／SIP聚集在核周或进入胞核,说明CacyBP／SIP存在细胞周期依赖性的核转位。在细胞的各时相中CacyBP／SIP总蛋白无明显变化,但在G2期时CacyBP／SIP的核蛋白表达水平增高。结论CacyBP／SIP存在细胞周期依赖的转位现象,可能参与了G2／M期的调控作用。     

Effects of small interfering RNA inhibit Class Ⅰ phosphoinositide 3-kinase on human gastric cancer cells

AIM:To investigate the effects of small interfering RNA(siRNA)-mediated inhibition of Class Ⅰ phosphoinositide 3-kinase(Class Ⅰ PI3K) signal transduction on the proliferation,apoptosis,and autophagy of gastric cancer SGC7901 and MGC803 cells.METHODS:We constructed the recombinant replication adenovirus PI3K(I)-RNA interference(RNAi)-green fluorescent protein(GFP) and control adenovirus NCRNAi-GFP,and infected it into human gastric cancer cells.MTT assay was used to determine the growth rate of the gastric cancer cells.Activation of autophagy was monitored with monodansylcadaverine(MDC) staining after adenovirus PI3K(I)-RNAi-GFP and control adenovirus NC-RNAi-GFP treatment.Immunofluorescence staining was used to detect the expression of microtubule-associated protein 1 light chain 3(LC3).Mitochondrial membrane potential was measured using the fluorescent probe JC-1.The expression of autophagy was monitored with MDC,LC3 staining,and transmission electron microscopy.Western blotting was used to detect p53,Beclin-1,Bcl-2,and LC3 protein expression in the culture supernatant.RESULTS:The viability of gastric cancer cells was inhibited after siRNA targeting to the Class Ⅰ PI3K blocked Class Ⅰ PI3K signal pathway.MTT assays revealed that,after SGC7901 cancer cells were treated with adenovirus PI3K(I)-RNAi-GFP,the rate of inhibition reached 27.48% ± 2.71% at 24 h,41.92% ± 2.02% at 48 h,and 50.85% ± 0.91% at 72 h.After MGC803 cancer cells were treated with adenovirus PI3K(I)-RNAiGFP,the rate of inhibition reached 24.39% ± 0.93% at 24 h,47.00% ± 0.87% at 48 h,and 70.30% ± 0.86% at 72 h(P < 0.05 compared to control group).It was determined that when 50 MOI,the transfection efficiency was 95% ± 2.4%.Adenovirus PI3K(I)RNAi-GFP(50 MOI) induced mitochondrial dysfunction and activated cell apoptosis in SGC7901 cells,and the results described here prove that RNAi of Class Ⅰ PI3K induced apoptosis in SGC7901 cells.The results showed that adenovirus PI3K(I)-RNAi-GFP transfection induced punctate distribution of     

Caveolin-1对胃癌细胞系MGC803细胞生长的影响

目的:研究Caveolin-1对胃癌细胞增殖、分化的影响,以探讨Caveolin-1作为基因治疗的候选基因的可能性．方法:运用基因重组技术,将人全长 Caveolin-1基因稳定转染胃癌细胞系MGC803．建立能稳定表达Caveolin-1的胃癌细胞系．同时建立空载体转染的MGC803细胞系作为空白对照,另用PD98059处理48 h作为阳性对照．以重组细胞系作为研究模型,通过免疫细胞化学及Western blot确认Caveolin-1蛋白在被转染细胞中的稳定表达．运用光学显微镜观察转染前后MGC803细胞形态的变化;另运用细胞计数检测了Caveolin-1对MGC803细胞生长的影响,流式细胞术分析了Caveolin-1对MGC803 细胞周期分布的影响．结果:Western blot结果显示,基因转染组及阳性对照组细胞中Vaveolin-1表达比未处理组细胞中明显增强(P<0．001,q值分别为23．067 与13.3376),且基因转染组中Caveolin-1表达比阳性对照组更强(P<0．00l,q=9．7294);基因转染后的MGC803细胞形态发生明显变化,由异形性明显、核大、胞质很少、核分裂明显变得形态较一致、胞质丰富、核／质比明显变小、核分裂相很少见;基因转染后细胞的群体倍增时间明显延长,由46．67 h延长至65．46 h,差异有统计学意义(P<0．05,q =4．8695):基因转染后细胞周期分布发生了明显变化,G0／G1期细胞数明显增多(P<0．01, q=9．1824),S期细胞数明显减少(P<0．01,q= 7．827),G2／M期细胞数无明显变化(P>0．05), Caveolin-1基因转染组与阳性对照组间细胞周期分布的变化也有明显差异性(其中G0／G1期 P<0．01,q=4．9323;S期P<0．05,q=3．3295)．结论:Caveolin-1既能诱导MGC803细胞分化又能将其阻滞于G0/G1期,通过延长细胞群体倍增时间而抑制胃癌细胞的体外增殖．     

Induction of apoptosis by arsenic trioxide and hydroxy camptothecin in gastriccancer cells in vitro

AIM To study the effects of arsenic trioxide and HCPT on different degrees of differentiated gastric cancer cells (SGC-7901, MKN-45, MKN-28)with respect to both cytotoxicity and induction of apoptosis in vitro. ~ODS The cytotoxicity of As2O3 and HCPT on gastric cancer cells was determined by MTTassay. Morphologic changes of apoptosis of gastric cancer cells were observed by light microscopy and transmission electron microscopy. Apoptosis and cell cycle changes of gastric cancer cells induced by HCPT and As2O3 were investigated by TUNEL method and flow cytometry. RESULTS As2O3 and HCPT had remarkable cytotoxic effects on different degrees of differentiated gastric cancer cells. The IC50 of As2O3 on well differentiated gastric cancer cell MKN-28, moderately differentiated gastric cancer cell SGC-7901, and poorly differentiated gastric cancer cell MKN-28 were 8. 91 μmol/L, 10. 57 μmol/L, and 11.65 μmol/L, respectively. The IC50 of HCPT on MKN-28, SGC-7901, and MKN-45 were 9. 35 rg/L, 10. 21 rg/L, and 12. 63 mg/L respectively after 48 h treatment. After 12 h of exposure to both drugs, gastric cancer cells exhibited morphologic features of apoptosis, including cell shrinkage, nuclear condensation,and formation of apoptotic bodies. A typical subdiploid peak before G0/G1 phase was observed by flow cytometry. The apoptotic rates of SGC7901, MKN-45, and MKN-28 were 13. 84%, 22.52%, and 9. 68%, respectively after 48 h exposure to 10 μmol/L As2O3. The apoptotic rates of SGC-7901, MKN-45, and MKN-28 were 21.88%, 12.35%, and 30. 26%, respectively after 48 h exposure to 10 mg/L HCPT. The apoptotic indice were 7% - 15% as assessed by TUNEL method. The effect of As2O3 on SGC-7901 showed remarkable cell cycle specificity, which induced cell death in G1 phase, and blocked G2/M phase. HCPT also showed a remarkable cell cycle specificity, by inducing cell death and apoptosis in G1 phase and arrest of proliferation at S phase. CONCLUSION AS2O3 and HCPT exhibit significant cytotoxicity on gastric cancer cells by induction of apoptosis. As2O3 and HCPT might have a promising prospect in the treatment of gastric cancer, which needs to be further studied.     

土槿乙酸对不同人肿瘤细胞系的抑制作用及机制

目的探讨土槿乙酸（PLAB）对人不同肿瘤细胞系的抑瘤作用及其机制。方法将MGC803、AGS、SMMC7721、LOVO、A375、SK-28和624reel细胞培养后,取对数生长期细胞,采用不同浓度PLAB干预;采用MTT法检测肿瘤细胞存活率;RT—PCR法检测细胞内过氧化物酶体增殖物活化受体γ（PPARγ）mRNA表达;流式细胞术检测细胞周期变化。结果PLAB干预后肿瘤细胞存活率明显降低,呈时间和剂量依赖性（P均〈0．05）;PPAR3,mR—NA在MGC803细胞中表达最强,SMMC7721细胞中次之,LOVO细胞中表达最低;PLAB（10μmol／L）作用肿瘤细胞后,AGS、MGC803、SK-28细胞G2／M期细胞百分比明显增加（P〈0．05）。结论PLAB在体外能明显诱导肿瘤细胞G2／M期阻滞,在表达野生型p53的肿瘤细胞,可能与抑制p53表达有关;在表达突变型p53的肿瘤细胞,可能与激活PPARγ表达有关。     

核糖体蛋白L5在胃癌中的表达及功能

目的:探讨核糖体蛋白L5(ribosomal protein L5,RPL5) 在胃癌细胞中的表达及对胃癌细胞生长的影响．方法:Western blot检测RPL5在胃癌细胞系中的表达, 构建RPL5特异性siRNA载体,转染细胞,Western blot进行鉴定,MTT方法和流式细胞术检测转染细胞的生长变化．结果:RPL5在胃癌细胞系AGS、MKN45、SGC7901、 MGC803中的表达均明显强于在GES-1和正常胃黏膜上皮中的表达．成功构建RPL5特异siRNA载体U6- RPL5A和U6-RPL5B,转染AGS细胞,进行稳定筛选,发现U6-RPL5A能显著抑制RPL5的表达,其相应的细胞系AGS-U6-RPL5A的生长速度减慢．细胞周期检测结果显示AGS-U6-RPL5A细胞中处于增殖期的细胞减少了约5％．结论:对RPL5功能的进一步深入研究可能会有助于胃癌的诊断和治疗．     

羟基喜树碱诱导胃癌细胞凋亡的作用机制初步研究

目的：研究羟基喜树碱（HCPT）诱导胃癌细胞的凋亡作用及对凋亡相关基因p53,c-myc,bcl-2,bcl-xl和bcl-xs表达的影响,探讨其诱导胃癌细胞凋亡的作用机制。方法：应用TUNEL染色、流式仪、免疫组化和RT－PCR技术等研究HCPT对胃细胞SGC－7901和MKN－45的诱导凋亡作用和对凋亡相关有达的影响。结果：HCPT作用于细胞后,可看到较为典型的细胞凋亡的形态学变化;细胞核固缩,染色质凝集,呈新月型紧核膜周边,核碎裂,染色质片段化,凋亡小体形成等。流式细胞仪DNA直方图上出现典型的亚二倍体的“凋亡峰”。流式细胞仪计数显示,10μg/ml的HCPT诱导胃癌细胞SGC－7901和MKN－45的凋亡率为21．88％和12．34％。TUNEL染色法显示,细胞凋亡指数在1．865－9．54％之间。免疫组化和RT－PCR结果显示：HCPT能够明显下调SGC－7901细胞的P53和bcl-2基因的蛋白和mRNA表达,对SGC－7901细胞的c-myc,bcl-xl和bcl-xs基因的蛋白表达无影响。HCPT作用后MKN－45细胞的p53蛋白和mRNA的表达增加,对MKN－45细胞的bcl-2,c-myc,bcl-xl和bcl-xs基因的表达无影响。结论：HCPT能够诱导胃癌细胞凋亡,可能是通过调控胃癌细胞的P53和bcl-2的表达而诱导胃癌细胞凋亡。     

Suppression of P-gp induced multiple drug resistance in a drug resistant gastric cancer cell line by overexpression of Fas

AIM:To observe the drug sensitizing effect and related mechanisms of fas gene transduction on human drug-resistant gastric cancer cell SGC7901/VCR (resistant to Vincristine).METHODS:The cell cycle alteration was observed by FACS. The sensitivity of gastric cancer cells to apoptosis was determined by in vitro apoptosis assay. The drug sensitization of cells to several anti-tumor drugs was observed by MTT assay. Immunochemical method was used to show expression of P-gp and Topo II in gastric cancer cells.RESULTS:Comparing to SGC7901 and pBK-SGC7901/VCR, fas-SGC7901/VCR showed decreasing G2 cells and increasing S cells, the G2 phase fraction of pBK-SGC7901/VCR was about 3.0 times that of fas -SGC7901/VCR but S phase fraction of fas -SGC7901/VCR was about 1.9 times that of pBK-SGC7901/VCR, indicating S phase arrest of fas-SGC7901/VCR. FACS also suggested apoptosis of fas-SGC7901/VCR.fas-SGC7901/VCR was more sensitive to apoptosis inducing agent VM-26 than pBK-SGC7901/VCR. MTT assay showed increased sensitization of fas-SGC7901/VCR to DDP, MMC and 5-FU, but same sensitization to VCR according to pBK-SGC7901/VCR. SGC7901, PBK-SGC7901/VCR and fas -SGC7901/VCR had positively stained Topo II equally. P-gp staining in pBK-SGC7901/VCR was stronger than in SGC7901, but there was little staining of P-gp in fas-SGC7901/VCR.CONCLUSION:fas gene transduction could reverse the MDR of human drug-resistant gastric cancer cell SGC7901/VCR to a degree, possibly because of higher sensitization to apoptosis and decreased expression of P-gp.     

Antiproliferative effect of octreotide on gastric cancer cells mediated by inhibition of Akt／PKB and telomerase

AIM: To investigate the antiproliferative effect of octreotide,a long-acting analogue of somatostatin, on gastric cancer cell line SGC7901 and its possible molecular mechanisms.METHODS: Gastric cancer cell line SGC7901 employed in the study was treated with 0.008, 0.04, 0.2, 1, 5 and 25μg@ml-1 of octreotide respectively for 24 h to evaluate the antiproliferative effect of somatostatin analog on the tumor cells by MTT assay method. To elucidate the underlying mechanism, the cells were exposed to 1 μg@ml-1 of octreotide for 0, 12, 24 and 48 h, when their Akt/PKB and telomerase activities were respectively determined using PCR-ELSIA and nonradioactive protein kinase assay protocols. The same experimental procedures were also performed in the control cells that were treated with corresponding vehicles instead of somatostatin analog.RESULTS: After exposed to octreotide for 24 h at the concentrations of more than 1 μg@ml-1 SGC7901 cells exhibited a dose-dependent inhibition of growth with the inhibiting rate to be as high as 34.66 % when 25 μg@ml-1 of octreotide was applied. The Akt/PKB and telomerase activity of SGC7901 cells was significantly inhibited when the cells were exposed to 1 μg@ml-1 of octreotide for 12, 24 and 48 h compared with that of their control counterparts (P＜0.01),both of which exhibited in a time-dependent manner.CONCLUSION: The antiproliferative effect of octreotide on SGC7901 cells might be mediated by the inhibition of Akt/PKB and telomerase.     

Nimesulide inhibits proliferation via induction of apoptosis and cell cycle arrest in human gastric adenocarcinoma cell line

AIM: To evaluate the potential role of Nimesulide, a selective COX-2 inhibitor, in proliferation and apoptosis of gastric adenocarcinoma cells SGC7901. METHODS: Cell counts and MTT assay were used to quantify the influence of Nimesulide in the proliferation of SGC7901 cells. Transmission electron microscopy and flow cytometry were used to observe the induction of Nimesulide the apoptosis of SGC7901 cells and influence in the distribution of cell cycle. The expression of P27(kip1) protein was observed by immunocytochemical staining. RESULTS: SGC-7901 Cells treated with Nimesulide at various concentrations exhibited a profound dose- and time-dependent reduction in the proliferation rate over the 72 h test period. The highest survival rate of the cells was 78.7 %, but the lowest being 22.7 %. Nimesulide induced apoptosis of the cells in a dose-dependent and non-linear manner and increased the proportion of cells in the G(0)/G(1) phase and decreased the proportion in the S and G(2)/M phase of the cell cycle. Meanwhile, Nimesulide could up-regulate the expression of P27(kip1) protein. CONCLUSION: The induction of apoptosis and cell cycle arrest are both anti-proliferative responses that likely contribute to the antineoplastic action of nimesulide on SGC-7901 cells. The up-regulation of P27(kip1) gene may contribute to the accumulation of these cells in the G(0)/G(1) phase following treatment with Nimesulide. Selective COX-2 inhibitor may be a new channel of the chemoprevention and chemotherapy for gastric carcinoma.     

丹参素对胃癌MGC803细胞周期的影响及凋亡诱导作用

目的研究丹参素的体外抗肿瘤细胞增殖作用及其分子机制。方法 MTT法检测丹参素对人肿瘤细胞的抗增殖作用,流式细胞术检测细胞周期分布的改变及细胞凋亡,Western blot检测细胞周期素CyclinB1蛋白的表达,比色法测定Caspase-3和Caspase-6的活性。结果丹参素可诱导MGC803细胞出现G2/M期阻滞并诱导细胞凋亡。细胞中CyclinB1蛋白表达下调,Caspase-3和Caspase-6的活性显著升高。结论丹参素具有抗肿瘤细胞增殖作用,通过抑制细胞周期素CyclinB1表达诱导细胞周期阻滞和细胞凋亡。     

肼屈嗪对人胃癌细胞株RUNX3基因甲基化及其表达的调节作用

背景:甲基化所致的抑癌基因RUNX3表达沉默是胃癌发生的重要机制,以脱甲基化制剂恢复其表达可起到抗肿瘤作用。目的:研究脱甲基化制剂肼屈嗪对人胃癌细胞株RUNX3基因甲基化及其表达的调节作用,观察肼屈嗪对胃癌细胞生长和凋亡的影响。方法:分别以RT-PCR和甲基化特异性PCR(MSP)检测肼屈嗪和5-Aza-dC处理前后SGC7901、MKN28和MGC803细胞的RUNX3 mRNA表达及其甲基化状态。以MTT法检测MKN28细胞增殖活性,以流式细胞术检测细胞周期和细胞凋亡。结果:MKN28细胞存在甲基化所致的RUNX3基因表达沉默。40μmol/L肼屈嗪作用72 h后,MKN28细胞可扩增出 RUNX3非甲基化条带,呈部分脱甲基化,RUNX3 mRNA恢复表达,但相对表达量低于5-Aza-dC组(P0.05)。10μmol/L以上浓度的肼屈嗪对MKN28细胞生长具有抑制作用,可使细胞周期阻滞于G0/G1期,并诱导细胞凋亡(P0.05)。结论:肼屈嗪可通过脱甲基化恢复RUNX3基因表达并能抑制MKN28细胞生长,诱导细胞凋亡。有必要对肼屈嗪在胃癌治疗中的作用作进一步研究。     

Function of chloride intracellular channel 1 in gastric cancer cells

AIM: To investigate the effect of chloride intracellular channel 1 (CLIC1) on the cell proliferation, apoptosis, migration and invasion of gastric cancer cells.METHODS: CLIC1 expression was evaluated in human gastric cancer cell lines SGC-7901 and MGC-803 by real time polymerase chain reaction (RT-PCR). Four segments of small interference RNA (siRNA) targeting CLIC1 mRNA and a no-sense control segment were designed by bioinformatics technology. CLIC1 siRNA was selected using Lipofectamine 2000 and transfected transiently into human gastric cancer SGC-7901 and MGC-803 cells. The transfected efficiency was observed under fluorescence microscope. After transfection, mRNA expression of CLIC1 was detected with RT-PCR and Western blotting was used to detect the protein expression. Proliferation was examined by methyl thiazolyl tetrazolium and apoptosis was detected with flow cytometry. Polycarbonate membrane transwell chamber and Matrigel were used for the detection of the changes of invasion and migration of the two cell lines.RESULTS: In gastric cancer cell lines SGC-7901 and MGC-803, CLIC1 was obviously expressed and CLIC1 siRNA could effectively suppress the expression of CLIC1 protein and mRNA. Proliferation of cells transfected with CLIC1 siRNA3 was enhanced notably, and the highest proliferation rate was 23.3% (P = 0.002) in SGC-7901 and 35.55% (P = 0.001) in MGC-803 cells at 48 h. The G2/M phase proportion increased, while G0/G1 and S phase proportions decreased. The apoptotic rate of the CLIC1 siRNA3 group obviously decreased in both SGC-7901 cells (62.24%, P = 0.000) and MGC-803 cells (52.67%, P = 0.004). Down-regulation of CLIC1 led to the inhibition of invasion and migration by 54.31% (P = 0.000) and 33.62% (P = 0.001) in SGC-7901 and 40.74% (P = 0.000) and 29.26% (P = 0.002) in MGC-803. However, there was no significant difference between the mock group cells and the negative control group cells.CONCLUSION: High CLIC1 expression can efficiently inhibit proliferation and enhance apoptosis, migration and invasion of gastric cancer cells in vitro. CLIC1 might be a promising target for the treatment of gastric cancer.