hPOT1 RNA干扰对人胃癌BGC823细胞突变型p53表达的影响

目的通过RNA干扰技术抑制人胃癌细胞BGC823中人端粒保护蛋白（human protection of telomeresl，hPOTl）的表达，观察hPOTl RNA干扰对胃癌BGC823细胞突变型p53基因转录水平的影响。方法从hPOTl编码区外显子8的区域选取一段19个碱基的序列gtactagaagcctatctca为RNA干扰靶向序列，构建hPOTl的RNA干扰真核表达载体，转人体外培养的低分化人胃癌细胞BGC823，提取细胞总RNA，半定量RT-PCR检测hPOTl和突变型p53基因mRNA表达水平的改变，验证hPOTlRNA干扰载体的基因沉默效率，了解抑制hPOTl表达后突变型p53基因mRNA水平的改变。结果经DNA测序鉴定，hPOTlRNA干扰载体包含干扰序列的插入片段，插入位置正确。经半定量RT-PCR鉴定，RNA干扰组细胞的hPOTl mRNA表达水平明显下调，基因沉默效率在70％左右；突变型p53表达下调。结论通过RNA干扰技术抑制人胃癌细胞BGC823中hPOTl表达后，突变型p53表达下调，提示hPOTl与突变型p53之间有一定的相关性。     

hPOT1 RNA干扰对人胃癌细胞株BGC-823端粒长度和hTERT表达的影响

人端粒保护蛋白1（hPOT1）的主要作用为保护端粒和调节端粒长度。目的：探讨hPOT1在人胃癌细胞中对端粒长度的调节作用及其可能机制。方法：以RNA干扰（RNAi）技术抑制人胃癌细胞株BGC-823中hPOT1的表达．以实时荧光定量聚合酶链反应（PCR）检测细胞端粒长度，以半定量逆转录聚合酶链反应（RT—PCR）检测人端粒酶逆转录酶（hTERT）mRNA表达。结果：以RNAi技术抑制hPOT1表达后，BGC-823细胞端粒长度明显缩短，反映端粒相对长度的T／S值显著小于亲本BGC-823细胞组和阴性对照组（1．383±0．091对2．758±0．647和3．043±0．548，P〈0．05），亲本细胞组与阴性对照组之间则无明显差异。hPOT1RNAi组细胞hTERTmRNA表达亦明显下调。结论：在人胃癌细胞中，hPOT1能正性调节端粒长度；在hPOT1下调引起端粒缩短的环节中，hTERT表达下降可能起一定作用。     

RNA干扰FLOT2基因表达下调NF-κB信号对胃癌细胞凋亡诱导作用研究

目的 探讨RNA干扰FLOT2基因表达对胃癌细胞凋亡及NF-κB信号的影响。方法 Western blotting检测人胃癌BGC823、SGC7901和MKN28细胞中FLOT2蛋白表达。BGC823细胞分为空白组、阴性组和si-FLOT2组,参照脂质体Lipofectamine~(TM)2000将siRNA转染细胞,细胞转染48 h,Western blotting检测FLOT2、NF-κB p65、IKK-β、p-IKK-β和Bax的蛋白表达。流式细胞术检测细胞凋亡率。结果 BGC823、SGC7901和MKN28胃癌细胞中FLOT2蛋白表达均显著高于人正常胃黏膜上皮细胞GES1(P0.05)。转染si-FLOT2的BGC823细胞FLOT2蛋白表达显著低于空白组(P0.05)。与空白组比较,si-FLOT2组细胞凋亡率显著升高,NF-κB p65、IKK-β和p-IKK-β蛋白表达显著降低,Bax蛋白表达显著升高(P0.05)。结论 RNA干扰FLOT2基因表达可诱导胃癌细胞凋亡,机制可能与下调NF-κB信号通路有关。     

TRF1、TRF2及POT1 mRNA在前列腺癌组织中的表达及临床意义

目的探讨端粒重复序列结合蛋白质(TRF)1、TRF2和端粒保护蛋白1(POT1)mRNA在前列腺癌(PCa)组织中的表达及临床意义。方法选择行尿道前列腺电切术切除的PCa患者中心组织标本55例作为实验组;同期选择55例前列腺增生(BPH)患者病理组织标本作为对照组。通过免疫组化法测定PCa患者肿瘤组织中TRF1、TRF2和POT1 mRNA的表达情况。结果实验组TRF1 mRNA明显高于对照组(P0.05),两组TRF2 mRNA差异无统计学意义(P0.05),实验组POT1 mRNA明显高于对照组(P0.05)。结论 PCa患者组织中TRF1和POT1 mRNA表达上升,说明它们的高表达可能与PCa发生发展密切相关;而PCa患者组织中TRF2的mRNA表达并没有发生明显变化,其作用机制还有待进一步研究。     

长链非编码RNA核仁小分子RNA宿主基因1对胃癌细胞增殖和侵袭的影响

目的探讨长链非编码(lnc)RNA核仁小分子RNA宿主基因(SNHG)1在胃癌中的表达水平及其对胃癌细胞增殖和侵袭过程的影响。方法实时荧光定量-聚合酶链反应(qRT-PCR)检测SNHG1在胃癌细胞SGC7901、BGC823和正常胃上皮细胞NGEC中的表达水平及采用SUHG1的小干扰RNA(si-SNHG1)干扰后SNHG1的表达水平;噻唑蓝(MTT)法检测沉默SNHG1对SGC7901、BGC823细胞增殖的影响,Transwell小室检测沉默SNHG1对SGC7901、BGC823细胞侵袭能力的影响。Western印迹法检测沉默SNHG1前后增殖标志物Ki67和侵袭相关蛋白基质金属蛋白酶(MMP)-2、MMP-9在SGC7901、BGC823中的表达变化。结果 SNHG1在胃癌细胞株中的表达显著高于正常胃上皮细胞株(P0.05);沉默SNHG1能显著抑制Ki67、MMP-2、MMP-9的表达。结论 lncRNA SNHG1在胃癌细胞中高表达,沉默SNHG1对胃癌细胞的增殖、侵袭起抑制作用,SNHG1可能成为治疗胃癌的一个有效靶点。     

DNA损伤诱导胃癌细胞端粒酶活性和TRF2表达增高

目的:检测在化疗药引起胃癌细胞DNA损伤过程中端粒酶、TRF1和TRF2的表达.方法:用不同浓度足叶乙甙处理胃癌细胞SGC7901和MKN28,分别在3,6,12,24和36h进行检测.采用实时定量TRAP分析检测端粒酶活性;用实时RT-PCR检测hTERTmRNA表达;用Westernblot和实时RT-PCR检测TRF1和TRF2表达.结果:两种细胞端粒酶活性及TRF2mRNA表达均在药物处理的早期明显增高(P<0.05),且显示明显的药物浓度依赖性(P<0.05);TRF1表达稍增高,但无统计学意义(P>0.05).hTERTmRNA表达无明显改变(P>0.05).TRF2表达在蛋白和mRNA水平均增高(P<0.05).结论:端粒酶和TRF2参与化疗药引起的胃癌细胞DNA损伤反应.     

TRF2小干扰RNA载体的构建及表达

目的:构建TRF2小干扰RNA载体,观察其在胃癌细胞中的表达．方法:根据pSilencer3．1-H1载体要求设计两对小干扰RNA,退火后连接入载体相应位点．经双酶切及测序鉴定后分别转染多药耐药衍生胃癌细胞SGC7901／ADR和SGC7901/VCR． G418选择培养液培养2 mo选取转染组及对照组细胞克隆．MTT法检测转染对细胞生长增殖速度的影响．细胞用阿霉素和足叶乙甙处理 6h后Western blot法检测TRF2表达．结果:成功构建TRF2小干扰RNA载体,建立稳定转染细胞株,转染后TRF2表达明显降低,对细胞的生长增殖速度无明显影响(P>0．05)．结论:成功构建TRF2小干扰RNA载体及稳定转染细胞株．     

反义RNA对胃癌细胞MT1-MMP基因表达和侵袭性的抑制作用

目的:膜研究膜型-1基质金属蛋白酶(MT1- MMP)反义RNA对人胃癌细胞BGC823靶基因表达和侵袭特性的影响方法:利用基因重组技术构建人MT1-MMP反义RNA真核表达载体,转染人胃癌细胞BGC823,应用RT-PCR、MTT、明胶酶谱和体外侵袭实验等方法观察人胃癌细胞BGC823转染前后,MT1-MMP mRNA表达水平、细胞生长、明教酶A活性及细胞体外侵袭能力等指标的变化.结果:成功构建了MT1-MMP反义RNA真核表达载体pasMMP14,将其转染胃癌细胞BGC823后,与阴性对照组相比,实验组MT1- MMP mRNA表达水平降低,抑制率为36%.转染48 h,明教酶A的活化受到了明显抑制.转染72 h,细胞增殖明显受抑(t=2.358,P<0.01 vs空白组:t=2.727 P<0.01 vs阴性组).实验组的穿膜细胞数明显低于空白对照组和阴性对照组(t=5.744,P<0.01;t=5.695,P<0.01).结论:反义RNA对人胃癌细胞MT1-MMP基因表达和侵袭能力具有明显的抑制作用,MT1-MMP基因可作为胃癌抗侵袭治疗的分子靶点.     

下调Six1基因表达对胃癌细胞生物学特性及B7-H1表达的影响

目的探讨抑制胃癌细胞Six1表达对癌细胞增殖侵袭及B7-H1表达的影响及机制。方法以人正常胃黏膜上皮细胞GES-1为对照细胞,Western印迹检测胃癌MKN45、BGC823和AGS细胞Six1的蛋白表达;参照LipofectamineTM2000转染说明将非特异性siRNA(NC组)和Six1特异性的siRNA(si-Six1组)转染BGC823细胞,并设置空白对照组,转染48 h,通过MTT及Transwell小室分别检测各组细胞活力及侵袭能力;Western印迹检测Six1、B7-H1及JAK2/STAT3信号通路磷酸化的JAK2、STAT3及下游分子细胞周期蛋白(cyclin)D1和基质金属蛋白酶(MMP)-2的蛋白表达。结果胃癌MKN45、BGC823和AGS细胞Six1的表达均显著高于在GES-1细胞表达(P0.05);转染si-Six1的BGC823细胞Six1的蛋白表达显著低于空白对照组(P0.05);与NC组比较,si-Six1组细胞活力及侵袭能力均显著降低,B7-H1、p-JAK2、p-STAT3、cyclinD1和MMP-2的蛋白表达均显著降低(P0.05)。结论下调胃癌细胞Six1表达可降低癌细胞活力及侵袭能力,降低B7-H1表达,机制可能是抑制JAK2/STAT3信号通路。     

上调miR-7对胃癌细胞增殖凋亡的影响及其机制研究

目的探讨上调miR-7对胃癌细胞增殖凋亡的影响及其可能的作用机制。方法利用实时定量PCR(q PCR)检测人正常胃黏膜上皮RGM-1细胞和胃癌BGC823细胞中miR-7表达差异;采用脂质体转染法上调BGC823细胞中miR-7表达,并通过q PCR检测其转染效果;CCK-8法检测转染24 h、48 h和72 h后BGC823细胞的增殖情况;转染48 h后,流式细胞仪检测细胞周期分布和细胞凋亡的变化;Western blotting检测细胞周期蛋白D1(Cyclin D1)、细胞周期蛋白依赖激酶6(CDK6)、细胞周期蛋白依赖激酶4(CDK4)、活化的含半胱氨酸的天冬氨酸蛋白水解酶3(Cleaved Caspase-3)和B细胞淋巴瘤/白血病-2(Bcl-2)蛋白的表达。结果 miR-7在胃癌BGC823细胞中的表达明显低于正常胃黏膜上皮RGM-1细胞(P0.05)。转染miR-7 mimics后,与空白组相比,阴性组中miR-7表达水平无显著差异(P0.05),干扰组中miR-7表达显著上升(P0.05)。CCK-8检测结果显示,转染24 h、48 h和72 h后,干扰组BGC823细胞中的OD值较空白组显著降低(P0.05),而阴性组与空白组组间差异无统计学意义(P0.05)。流式细胞仪检测显示,与空白组相比,阴性组中G1期、S期、G2/M期细胞所占比例和细胞凋亡率差异无统计学意义(P0.05),而干扰组中G1期细胞所占比例和细胞凋亡率显著升高,S期和G2/M期细胞所占比例显著下降,差异均有统计学意义(P0.05)。Western blotting检测结果显示,上调miR-7表达后,BGC823细胞中CDK6、CDK4、Cyclin D1和Bcl-2蛋白的相对表达水平均显著下降,Cleaved Caspase-3蛋白表达量显著升高,差异均有统计学意义(P0.05)。结论上调miR-7可抑制胃癌细胞增殖,促进细胞凋亡,其作用机制可能与上调Cleaved Caspase-3蛋白表达、下调CDK6、CDK4、Cyclin D1和Bcl-2蛋白的表达有关。     

Effects of all-trans-retinoic on human gastric cancer cells BGC-823

OBJECTIVE: To determine the inhibitory effects of all‐trans‐retinoic acid (ATRA) on cell growth, cell cycle and vascular endothelial growth factor (VEGF) expression in the human gastric cancer cell line BGC‐823 in vitro. METHODS: Human gastric cancer BGC‐823 cells were treated with various concentrations of ATRA and the cell growth was then determined using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide viability assay. The cell cycle distribution was analyzed using a flow cytometer. The VEGF mRNA and protein expression were analyzed by semi‐quantitative RT‐PCR and Western blotting, respectively. RESULTS: ATRA at concentrations of 0.1–10 µmol/L inhibited the growth of BGC‐823 cells grown in culture; a time‐ and dose‐dependent inhibitory influence was found. ATRA arrested BGC‐823 cells at the G₀/G₁ phase in a dose‐dependent way. Both VEGF mRNA and protein were decreased by ATRA in a dose‐dependent way. CONCLUSION: The anti‐tumor effects of ATRA on human gastric cancer cells are associated with G₀/G₁ phase arrest and decreased VEGF expression.     

Characterization and cell cycle regulation of the related human telomeric proteins Pin2 and TRF1 suggest a role in mitosis

Telomeres are essential for preserving chromosome integrity during the cell cycle and have been specifically implicated in mitotic progression, but little is known about the signaling molecule(s) involved. The human telomeric repeat binding factor protein (TRF1) is shown to be important in regulating telomere length. However, nothing is known about its function and regulation during the cell cycle. The sequence of PIN2, one of three human genes (PIN1-3) we previously cloned whose products interact with the Aspergillus NIMA cell cycle regulatory protein kinase, reveals that it encodes a protein that is identical in sequence to TRF1 apart from an internal deletion of 20 amino acids; Pin2 and TRF1 may be derived from the same gene, PIN2/TRF1. However, in the cell Pin2 was found to be the major expressed product and to form homo- and heterodimers with TRF1; both dimers were localized at telomeres. Pin2 directly bound the human telomeric repeat DNA in vitro, and was localized to all telomeres uniformly in telomerase-positive cells. In contrast, in several cell lines that contain barely detectable telomerase activity, Pin2 was highly concentrated at only a few telomeres. Interestingly, the protein level of Pin2 was highly regulated during the cell cycle, being strikingly increased in G2+M and decreased in G1 cells. Moreover, overexpression of Pin2 resulted in an accumulation of HeLa cells in G2+M. These results indicate that Pin2 is the major human telomeric protein and is highly regulated during the cell cycle, with a possible role in mitosis. The results also suggest that Pin2/TRF1 may connect mitotic control to the telomere regulatory machinery whose deregulation has been implicated in cancer and aging.     

ANGPTL2 expression in gastric cancer tissues and cells and its biological behavior

AIM To explore expression of angiopoietin-like protein 2(ANGpT L2) and its effect on biological behavior such as proliferation and invasiveness in gastric cancer. METHODS Western blotting was used to detect expression of ANGp TL2 in 60 human normal gastric tissues, 60 human gastric cancer tissues and gastric cell lines including GES-1, N87, SGC7901, BGC823 and pA MC82. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) and Transwell assay were used to detect the proliferation and invasive ability of gastric cancer cells. RESULTS Compared to normal tissues, ANGp TL2 protein levels were significantly upregulated in gastric tissues, and this level was closely correlated with gastric tumor grade, clinical stage and lymph node metastasis. Compared to GES-1 cells, ANGpT L2 mR NA and protein levels were significantly increased in gastric cancer cells including N87, SGC7901, BGC823 and p AMC82. The expression of ANGpT L2 in highly malignant gastric cancer cell lines BGC823 and pA MC82 was significantly higher than in low malignancy gastric cancer cell lines N87 and SGC7901. MTT and Transwell experiments indicated that the proliferation rate and invasive ability of stable overexpressed gastric cancer cells was faster than in cells transfected with Lv-NC and blank controlcells, and the invasive ability of stable overexpressed gastric cancer cells was higher than that of cells transfected with Lv-NC and blank control cells.CONCLUSION ANGp TL2 contributed to proliferation and invasion of gastric cancer cells. In clinical treatment, ANGpT L2 may become a new target for treatment of gastric cancer.