Down-regulation of miR-212 expression by DNA hypermethylation in human gastric cancer cells

There has been few report discussing the expression and function of miR-212 in gastric cancer (GC). The aim of this pilot study was to investigate the expression of miR-212 in both gastric cancer tissues and gastric cancer cells and further explores the possible reasons for this change and the impact on the development of gastric cancer. qRT–PCR was used to detect the expression of miR-212 in primary GC tissues, adjacent normal tissues, gastric cancer cell lines BGC-823, SGC-7901, MKN-45, and normal gastric mucosa cell line GES. The expression of miR-212 was evaluated before and after treatment with methylation inhibitor-5-Aza-2′-deoxycitidine (5-Aza-dC), finally anti-miRNA and dual luciferase reporter assay were used to prove that MYC is a target gene of miR-212. The results showed that a significant reduction of miR-212 expression in GC tissues was observed compared to that in normal tissues (P = 0.002). At the same time, miR-212 expression level in normal gastric mucosa cell line GES was higher than that of in gastric cancer cell lines BGC-823, SGC-7901, and MKN-45 (P = 0.015, 0.008, 0.044, respectively). Computer sequence analysis showed the hypermethylation of CpG islands(CPI) in the promoter regions of miR-212 led to the lower expression of miR-212 in gastric cell strains (BGC-823 and SGC-7901). MiR-212 expression was significantly recovered after treatment with methylation inhibitor 5-Aza-dC (P = 0.016, 0.000, 0.015, respectively). Then, the results of AMOs transfection and dual luciferase reporter assay showed that Myc is a target of miR-212, which will be helpful to verify the function of miR-212 in carcinogenesis. The conclusion could be deduced from the study that decreased expression of miR-212 may be due to hypermethylation of CPI in gastric cancer cells, and miR-212 might act on the progression of gastric cancer through the potential target gene Myc.

     

miR-875-5p通过靶向USF2抑制胃癌细胞的增殖、迁移和侵袭

目的:探讨miR-875-5p对胃癌细胞增殖、迁移和侵袭的影响及其机制。方法:采用qPCR法检测胃癌细胞BGC-823、HGC-27、MGC-803、SGC-7901、AGS、MKN-45和胃黏膜上皮细胞GES-1中miR-875-5p的表达水平。利用脂质体转染技术,分别将miR-875-5p模拟物/抑制剂(mimic/inhibitor)及其阴性对照质粒(miR-NC/Anti-miR-NC)转染至AGS细胞/MKN-45细胞,构建过表达/抑制miR-875-5p的细胞模型,空白对照组(Control组)不转染。通过CCK-8、克隆形成、Transwell等实验分别检测miR-875-5p表达变化对细胞增殖、克隆形成、迁移和侵袭的影响。采用双荧光素酶报告基因实验验证miR-875-5p与上游刺激因子2(USF2)的靶向关系,WB实验验证miR-875-5p对USF2的调控作用并检测USF2蛋白的表达。构建MKN-45细胞裸鼠移植瘤模型,验证miR-875-5p过表达对MKN-45细胞成瘤能力的影响。结果:miR-875-5p在6种胃癌细胞中表达水平显著低于胃黏膜上皮细胞GES-1(均P<0.01)。与Control组和miR-NC组相比,miR-875-5p mimic组AGS细胞的增殖、克隆形成率、迁移和侵袭细胞数,以及USF2蛋白的表达均显著降低(P<0.05或P<0.01);miR-875-5p inhibitor组MKN-45细胞的增殖、克隆形成率、迁移和侵袭细胞数,以及USF2蛋白的表达均显著提高(P<0.05或P<0.01)。双荧光素酶报告基因实验证明,miR-875-5p能够直接靶向USF2基因。体内成瘤实验结果表明,过表达miR-875-5p显著抑制MKN-45细胞移植瘤的生长(均P<0.01)。结论:miR-875-5p通过靶向USF2抑制胃癌细胞的增殖、迁移和侵袭。     

Effects of MicroRNA-106 on Proliferation of Gastric Cancer Cell through Regulating p21 and E2F5

Objective: To investigate the effects of miR-106b on malignant characteristics of gastric cancer cells, andexplore possible mechanisms. Methods: Expression of miR-106b, p21 and E2F was determined by real-timePCR. Transfection with miR-106b mimics was conducted, and gastric cancer cells with miR-106b overexpressionwere obtained. Cells transfected with mimic mutants and those without transfection served as negative andblank controls, respectively. Flow cytometry and transwell assays were adopted to detect the effects of miR-106boverexpression on cell cycle, migration and invasion of gastric cancer cells. Results:. The expression of miR-106b in gastric cancer cells was significantly higher than that in normal gastric mucosa cells. Furthermore, theexpression level of miR-106b rose according to the degree of malignacy among the three GC cell strains (MKN-45 > SGC-7901 > MKN-28). Overexpression of miR-106b shortened the G0/G1 phase and accelerated cell cycleprogression, while reducing p21 and E2F5, without any significant effects on the capacity for migration andinvasion of gastric cancer cells. Conclusions: miR-106b may promote cell cycling of gastric cancer cells throughregulation of p21 and E2F5 target gene expression.     

miR-26a/b调控p53/MDM2通路对胃癌细胞凋亡的影响

目的 探讨miR-26a/b调控p53/MDM2通路对胃癌细胞凋亡的影响。方法 实时荧光定量PCR检测胃癌细胞系MGC803、MKN-45和MKN-28中miR-26a/b的表达水平,荧光素酶报告系统分析miR-26a/b与MDM2 3’非翻译区（3’UTR）的结合情况;将化学合成miR-26a/b前体分子mimics和无关序列转染胃癌细胞MKN-45,化学合成miR-26a/b inhibitor转染胃上皮细胞GES-1后,Western blotting检测MDM2、p53及其下游分子p21和Bcl-2的表达,MTT法检测转染24、48、72 和96 h的细胞增殖情况;通过Annexin Ⅴ/PI双染检测miR-26a/b对MKN-45细胞凋亡情况。结果 与永生化胃上皮细胞GES-1相比,miR-26a/b在肿瘤细胞系MGC803、MKN-45和MKN-28中的表达均下调,在MKN-45中表达水平最低;荧光素酶活性检测显示,miR-26a/b过表达抑制MDM2 3’UTR报告载体（Wild）的荧光素酶活性,而对3’UTR突变型报告载体（Mutation）荧光素酶活性无明显影响。miR-26a/b抑制MKN-45细胞中MDM2表达并增强p53及下游分子表达,而在GES-1细胞中抑制miR-26a/b可以增强MDM2表达,降低p53及下游分子表达。MTT结果显示,miR-26a/b抑制MKN-45细胞的增殖,miR-26a/b inhibitor则明显促进GES-1细胞的增殖。通过AnnexinⅤ/PI检测细胞凋亡发现,miR-26a/b过表达的MKN-45细胞的凋亡率高于对照细胞（P＜0.01）。结论 miR-26a/b 能与MDM2 3’UTR 特异结合,调控p53/MDM2通路影响胃癌细胞的增殖及凋亡。     

长链非编码RNA NR2F2-AS1对胃癌细胞增殖、凋亡的影响

目的:研究lncRNA NR2F2-AS1对胃癌细胞增殖、凋亡的影响,并探讨其机制。方法:运用qRT-PCR法检测细胞中 NR2F2-AS1、miR-425-5p的mRNA表达情况;将pcDNA组（转染pcDNA）、pcDNA-NR2F2-AS1组（转染pcDNA-NR2F2-AS1）、sh-NR2F2-AS1组(转染sh-NR2F2-AS1)、sh-NC组(转染sh-NC)、anti-miR-NC组（转染anti-miR-NC）、anti-miR-425-5p组（转染anti-miR-425-5p）、pcDNA-NR2F2-AS1+miR-NC组（共转染pcDNA-NR2F2-AS1和miR-NC）、pcDNA-NR2F2-AS1+miR-425-5p组（共转染pcDNA-NR2F2-AS1和miR-425-5p mimics）转染至MGC-803、MKN-45细胞;MTT法检测细胞的增殖;流式细胞术检测细胞的凋亡;双荧光素酶报告基因检测实验检测细胞的荧光活性。结果:与正常胃黏膜上皮细胞GES-1相比,胃癌细胞MGC-803、MKN-45中NR2F2-AS1的表达显著降低,miR-425-5p的表达显著升高;过表达NR2F2-AS1、抑制miR-425-5p均可抑制胃癌细胞增殖,促进细胞凋亡;miR-425-5p可抑制野生型NR2F2-AS1的MGC-803、MKN-45细胞的荧光活性;过表达miR-425-5p可逆转过表达NR2F2-AS1对MGC-803、MKN-45细胞增殖和凋亡的作用。结论:lncRNA NR2F2-AS1可抑制胃癌细胞的增殖,促进细胞凋亡,其机制可能与靶向miR-425-5p有关,将可为胃癌的治疗提供新靶点。     

miR-133在胃癌组织中的表达及对胃癌细胞恶性行为的影响

目的 探讨microRNA-133（miR-133）在胃癌组织及细胞系中的表达情况,并探讨其对胃癌细胞凋亡和侵袭的影响。方法 采用实时定量PCR（qPCR）检测64例胃癌组织及对应癌旁组织中的miR-133水平,分析miR-133表达与临床病理参数（性别、年龄、肿瘤位置、临床分期、分化程度、浸润深度及淋巴结转移）的关系,并检测其在胃癌细胞株AGS、SGC-7901、MKN-1、MKN-45、MGC-803和BGC-823及正常胃黏膜细胞GES-1细胞的表达情况,同时选取miR-133水平最低的胃癌细胞并转染过表达miR-133的真核重组质粒pCDNA3.1+miR-133,转染后分别采用流式细胞仪PI/Annexin V双染法及Transwell法检测miR-133对细胞凋亡和侵袭能力的影响。结果 胃癌组织的miR-133相对表达量为0.347±0.024,低于癌旁组织（P＜0.05）,且其表达与临床分期、分化程度、浸润深度及淋巴结转移有关均有关（P＜0.05）;与GES-1细胞相比（其miR-133表达水平设为1.00）,胃癌细胞的miR-133水平均较低（P＜0.05）,且MKN-45的表达水平最低;与对照组和空转染组相比,过表达组转染48、96 h后的细胞凋亡水平均升高,且穿膜细胞数均降低（P＜0.05）。结论miR-133在胃癌组织和细胞中均为低表达,上调miR-133水平可抑制胃癌细胞的侵袭并诱导凋亡。     

基于miRNA-mRNA网络筛查并验证胃癌诊断和预后评估相关的标志物及其潜在分子机制

目的：通过生物信息学方法探索并实验验证胃癌相关标志物miR-1-3p对胃癌细胞增殖的作用及其分子机制。方法：收集TCGA数据库中胃癌（n=375）及癌旁组织（n=45）的转录组数据,构建胃癌特异性mRNA-miRNA网络,筛选潜在的miRNA类标志物,利用TargetScan预测标志物的下游靶基因且分析它们的功能。选取人正常胃上皮细胞GES-1及胃癌细胞AGS、MKN45、NCI-N87,用q PCR法检测细胞中miR-1-3p和心肌蛋白（MYOCD）的表达,用lipofectamine 2000将miR-1-3p模拟物转染至胃癌细胞中,CCK-8法测定轨染后细胞的增殖能力,WB法测定MYOCD的表达量,双荧光素酶报告基因实验验证miR-1-3p与MYOCD之间的靶向结合关系。结果：通过数据库数据分析得到差异表达的259个miRNA和7 545个mRNA,构建胃癌特异性mRNAmiRNA调节网络,分析网络中脆弱结构后确定miR-1-3p为潜在的胃癌标志物,ROC曲线和Kaplan-Meier分析显示其对胃癌的诊断和预后评估有重要意义。细胞实验显示miR-1-3p在胃癌细胞中呈低表达（P...     

miR-361-5p通过靶向CCND1逆转胃癌SGC-7901细胞奥沙利铂耐药性

目的:探讨miR-361-5p对胃癌SGC-7901细胞奥沙利铂(oxaliplatin,OXA)耐药性的影响及其作用机制.方法:采用qPCR法检测miR-361-5p在胃癌细胞MKN-45、MGC80-3、SGC-7901和OXA耐药细胞SGC-7901/OXA中的表达水平.利用脂质体转染技术分别将miR-361-5...     

敲低膜联蛋白A5对人胃癌细胞系MKN-45增殖的作用

目的 探讨膜联蛋白A5低表达对人胃癌MKN-45细胞增殖和凋亡的影响。方法 将胃癌MKN-45细胞分为siRNA干扰组、阴性对照组和空白对照组。采用RNA干扰技术将靶向膜联蛋白A5的siRNA和阴性对照siRNA脂质体转染法转染细胞,转染48 h后采用qRT-PCR和Western blot法分别在mRNA水平和蛋白水平进行抑制效率的鉴定,空白对照组不予任何处理。应用MTT、平板克隆形成法检测膜联蛋白A5低表达对胃癌MKN-45细胞增殖的影响,流式细胞术检测细胞凋亡情况。Western blot法检测增殖核抗原PCNA和周期相关蛋白Cyclin D1的表达。结果 靶向膜联蛋白A5的siRNA转染后,胃癌MKN-45细胞中膜联蛋白A5的表达较阴性对照和空白对照组明显降低（P<0.05）。MTT和克隆形成实验可见siRNA干扰组细胞增殖活力和集落形成能力较阴性对照和空白对照组显著增高（P<0.05）;流式细胞术显示细胞凋亡率无明显改变;PCNA和Cyclin D1的表达显著上调。结论 膜联蛋白A5低表达能促进胃癌细胞的增殖。     

miR-101靶向甲基化转移酶3A抑制人卵巢癌细胞生长与侵袭

背景与目的：miR-101在胃癌、结肠癌、乳腺癌以及前列腺癌中表达下调,有类似抑癌基因样作用,然而,其在卵巢癌中的作用尚未明确。该研究旨在探讨miR-101是否通过靶向调控甲基化转移酶3A(DNMT3A)抑制人卵巢癌细胞生长与侵袭,从而进一步揭示miR-101的抑瘤机制。方法：采用实时定量聚合酶链式反应(quantitative real-time polymerase chain reaction,qRT-PCR)检测22例卵巢癌组织及癌旁正常卵巢组织中miR-101的表达改变;将miR-101 mimics转染于卵巢癌SKOV3细胞,以DNMT3A siRNA为阳性对照,采用蛋白［质］印迹法(Western blot)检测外源过表达miR-101对DNMT3A蛋白表达水平的影响;采用噻唑蓝(thiazolyl blue,MTT)和Transwell侵袭实验检测外源高表达miR-101对人卵巢癌细胞生长与侵袭能力的影响。结果：qRT-PCR检测结果显示,miR-101在22例卵巢癌组织中的表达水平较癌旁正常组织明显下调;Western blot检测结果显示,外源过表达miR-101或沉默DNMT3A能下调SKOV3细胞DNMT3A蛋白的表达水平;MTT检测结果显示,转染miR-101 mimics或沉默DNMT3A 48、72和96 h后D值与对照组比较明显减少,差异均有统计学意义(P<0.05);Transwell侵袭实验显示,转染miR-101 mimics或沉默DNMT3A 36 h后穿过基底膜的细胞数分别为(105±7)个和(107±13)个,与对照组(213±11)个比较能明显减缓SKOV3细胞的穿膜能力,差异有统计学意义(P<0.05)。结论：miR-101通过靶向调控DNMT3A抑制人卵巢癌细胞生长与侵袭。     

miR-106a靶向调控TIMP2对人胃癌细胞增殖、转移及EMT的影响

目的 探讨微小RNA-106a(miR-106a)在人胃癌组织中的表达及其与癌细胞增殖、转移的关系。方法 收集人胃癌和配对癌旁福尔马林固定-石蜡包埋样本共50对,Real-time PCR法检测miR-106a在人胃癌组织中的表达;培养人低分化胃癌细胞系SGC-7901、BGC-823、MKN-45和永生化人胃黏膜上皮细胞GES-1,Real-time PCR法检测miR-106a在人胃癌细胞中的表达;MTT法检测细胞增殖,Transwell法检测细胞迁移和侵袭,生物信息学和双荧光素酶法鉴定miR-106a靶基因,Western blot检测靶蛋白TIMP2、MMP2、MMP9、E-cadherin、N-cadherin表达。结果 Real-time PCR检测显示,与癌旁组织比较,miR-106a在人胃癌组织中高表达,差异有统计学意义(P＜0.001);与GES-1细胞比较,miR-106a在人胃癌细胞SGC-7901、BGC-823、MKN-45中普遍高表达,差异有统计学意义(P＜0.001)。MTT检测显示抑制miR-106a后胃癌细胞SGC-7901、BGC-823增殖能力下降(P＜0.01)。Transwell显示胃癌细胞BGC-823迁移、侵袭能力下降(P＜0.001)。双荧光素酶法显示TIMP2野生型报告基因与miR-106a mimic共转后,其荧光素酶活性较miR-106a NC组明显下降(P＜0.001),但TIMP2突变型报告基因无明显变化。Western blot显示抑制miR-106a后TIMP2表达升高,MMP2、MMP9表达下降,E-cadherin表达升高,N-cadherin表达下降。结论 miR-106a在人胃癌中的高表达可能通过靶向TIMP2而影响癌细胞的增殖、转移和上皮-间质转化。     

MicroRNA profiles of healthy basal and luminal mammary epithelial cells are distinct and reflected in different breast cancer subtypes

In order to determine the microRNA expression pattern in normal basal and luminal breast epithelium and to analyze the relationship of this expression pattern to different breast cancer subtypes, laser-microdissected luminal and basal cells isolated from plastic surgery tissue samples were used for comprehensive expression profiling, measuring 664 microRNAs by low-density TaqMan arrays. In a test (n = 5) and validation set (n = 9) 10 differentially expressed microRNAs were identified by TaqMan RT-qPCR. These microRNAs were studied in laser-microdissected cells of luminal A (n = 5), luminal B (n = 5), basal-like subtypes of breast cancer (n = 10), and malignant myoepithelioma of the breast (n = 10). From 116 microRNAs unequivocally expressed in normal breast epithelial cells, we identified 8 basal microRNAs (let7c, miR-125b, miR-126, miR-127-3p, miR-143, miR-145, miR-146b-5p, and miR-199a-3p), preferentially expressed in normal basal cells, exceeding luminal cells by a factor from 4 to 1000. All of these microRNAs were also found to be significantly elevated in malignant myoepithelioma but not in basal-type of breast cancer. Two members of the miR-200 family (miR-200c and miR-429) were predominantly luminal. Both microRNAs were expressed in the luminal and basal type of breast cancer in contrast to malignant myoepithelioma, which revealed significantly lower levels potentially contributing to its mesenchymal phenotype. In conclusion, normal luminal and basal mammary epithelial cells exhibit a different microRNA expression profile. Malignant myoepithelioma seems to exhibit a basal pattern of microRNA expression, whereas the so-called basal-like breast cancer is clearly different and reveals a luminal type pattern.     

RNA干扰乙醛脱氢酶1A1表达对胃癌细胞生物学行为的影响

目的 研究小RNA干扰乙醛脱氢酶1A1基因（ALDH1A1）表达对胃癌细胞生物学行为包括增殖、克隆形成和侵袭能力的影响。方法 构建表达ALDH1A1的siRNA的PGPU6／GFP／Neo-ALDH1A1真核细胞表达载体,转染人胃癌细胞系MKN-45细胞为实验组,同时设阴性对照组和空白对照组,Western blotting检测干扰ALDH1A1基因表达的效果。MTT法、克隆形成实验、Transwell 小室侵袭实验检测ALDH1A1表达下降后MKN-45细胞增殖、克隆形成和侵袭能力的情况。结果 Western blotting检测显示实验组MKN-45细胞ALDH1A1蛋白表达低于阴性对照组（0.36±0.04 vs. 0.72±0.08,P＜0.05）;MTT法显示实验组MKN-45细胞的增殖抑制率高于阴性对照组［（52.56±1.81）％ vs.（30.32±2.23）％,P＜0.05］;克隆形成实验显示实验组MKN-45细胞的克隆形成能力低于阴性对照组（21.67±2.00 vs. 36.78±3.53,P＜0.05）;Transwell 小室侵袭实验显示实验组胃癌细胞的侵袭能力低于阴性对照组（55.11±7.98 vs. 84.78±6.00,P＜0.05）。结论 通过RNA干扰技术可明显下调ALDH1A1蛋白在MKN-45细胞中表达,并抑制肿瘤细胞的增殖、克隆形成和侵袭能力。ALDH1A1有望成为胃癌治疗的一个新的靶点。     

Down-regulation of miR-212 expression by DNA hypermethylation in human gastric cancer cells

There has been few report discussing the expression and function of miR-212 in gastric cancer (GC). The aim of this pilot study was to investigate the expression of miR-212 in both gastric cancer tissues and gastric cancer cells and further explores the possible reasons for this change and the impact on the development of gastric cancer. qRT-PCR was used to detect the expression of miR-212 in primary GC tissues, adjacent normal tissues, gastric cancer cell lines BGC-823, SGC-7901, MKN-45, and normal gastric mucosa cell line GES. The expression of miR-212 was evaluated before and after treatment with methylation inhibitor-5-Aza-2'-deoxycitidine (5-Aza-dC), finally anti-miRNA and dual luciferase reporter assay were used to prove that MYC is a target gene of miR-212. The results showed that a significant reduction of miR-212 expression in GC tissues was observed compared to that in normal tissues (P = 0.002). At the same time, miR-212 expression level in normal gastric mucosa cell line GES was higher than that of in gastric cancer cell lines BGC-823, SGC-7901, and MKN-45 (P = 0.015, 0.008, 0.044, respectively). Computer sequence analysis showed the hypermethylation of CpG islands(CPI) in the promoter regions of miR-212 led to the lower expression of miR-212 in gastric cell strains (BGC-823 and SGC-7901). MiR-212 expression was significantly recovered after treatment with methylation inhibitor 5-Aza-dC (P = 0.016, 0.000, 0.015, respectively). Then, the results of AMOs transfection and dual luciferase reporter assay showed that Myc is a target of miR-212, which will be helpful to verify the function of miR-212 in carcinogenesis. The conclusion could be deduced from the study that decreased expression of miR-212 may be due to hypermethylation of CPI in gastric cancer cells, and miR-212 might act on the progression of gastric cancer through the potential target gene Myc.     

miR-34a regulates cisplatin-induce gastric cancer cell death by modulating PI3K/AKT/survivin pathway

The purposes of this study were to determine the expression profiles of microRNA-34a (miR-34a) in human gastric cancer cell line (SGC-7901) and cisplatin-resistant cell lines (SGC-7901/DDP), and to establish the correlation between miR-34a expression profile and the sensitivity of human gastric cancer cell to cisplatin-based pattern, thereby providing new methods and strategies for treating gastric cancer. Gastric cancer cell line (SGC-7901) and cisplatin-resistant cell line (SGC-7901/DDP) were cultivated in vitro, respectively. Quantitative real-time PCR (qRT-PCR) and Western blot were utilized to determine the expression profiles of miR-34a and survivin in both gastric cancer cell lines. With miR-34a mimic and miR-34a inhibitor transfected into SGC-7901 and SGC-7901/DDP for 48 h, post-transfection changes of miR-34a expression was determined; the effects of miR-34a ectopic expression on the viability of cisplatin-induce gastric cancer cell were assayed by the MTT method. The effects of miR-34a ectopic expression on apoptosis of cisplatin-induce gastric cancer cell were determined by Annexin V/propidium iodide (PI) double staining method and flow cytometry. The effects of miR-34a ectopic expression on the AKT and p-AKT expression of cisplatin-induce gastric cancer cells were determined by Western blot and flow cytometry with the PI3K pathway inhibitor Wortmannin. As shown by qRT-PCR and Western blot analyses, the expression of miR-34a in cisplatin-resistant cell lines decreased significantly in comparison to that of SGC-7901 cell line (p?<?0.05), while significant up-regulation of survivin expression was also observed (p?<?0.05). Compared with the control group, the expression of miR-34a increased significantly in SGC-7901 cells transfected with miR-34a mimic for 48 h (p?<?0.01). After miR-34a inhibitor transfection, the expression of miR-34a decreased significantly (p?<?0.05). The viability of cisplatin-induce gastric cancer cells increased significantly (p?<?0.05) with significant decrease of apoptosis after miR-34a expression inhibition, as demonstrated by MTT and flow cytometry with miR-34a over-expression, the viability of cisplatin-induce gastric cancer cells decreased significantly (p?<?0.05), with significant apoptosis increase (p?<?0.05). As shown by Western blot and flow cytometry, in comparison to the control group, Wortmannin could inhibit miR-34a inhibitor and DDP induced up-regulation of p-AKT significantly (p?<?0.05) and stimulated apoptosis. In conclusion, miR-34a expression was down-regulated in cisplatin-resistant cell lines. miR-34a over-expression could improve the sensitivity of gastric cancer cells against cisplatin-based chemotherapies, with PI3K/AKT/survivin signaling pathway possibly involved in the mechanism.     

MiR-184在人胃癌组织中的表达及对胃癌细胞凋亡的影响

[目的]探讨miR-184在人胃癌组织中的表达及对胃癌细胞凋亡的影响。[方法]使用Real-time PCR检测miR-184表达,SGC-7901细胞转染,MTT法检测细胞增殖情况,Hoechst33342染色观察细胞自噬、凋亡情况,Transwell法检测细胞侵袭能力应用,流式细胞术检测细胞凋亡情况,Western blot检测各组细胞NF-κB、LC3Ⅱ、Beclin1蛋白表达。[结果](1)胃癌组织的miR-184表达水平显著低于正常胃组织(1.74±0.12 vs 2.51±0.41,t=12.745,P<0.001)。(2)转染1d后,miR-184 mimics组的miR-184表达水平(6.02±1.15)显著高于NC组(2.15±0.37)(t=22.652,P<0.001),miR-184 inhibitors组表达水平(0.52±0.09)显著低于NC组(t=30.268,P<0.001)。(3)24~72h内,miR-184 inhibitors组和NC组的细胞增殖能力显著性高于miR-184 mimics组(P<0.05)。(4)Mi R-184 mimics组(45.39%±1.74%)侵袭率显著低于NC组(52.05%±2.03%)(t=17.614,P<0.001),而miR-184 inhibitors组(94.51%±3.08%)侵袭率显著高于NC组(t=22.652,P<0.001)。(5)MiR-184 mimics组(72.32%±22.82%)细胞凋亡率显著高于NC组(44.07%±16.23%)(t=7.133,P<0.001),而miR-184 inhibitors组(35.31%±11.29%)凋亡率显著低于NC组细胞(t=3.133,P=0.001)。(6)MiR-184 mimics组可见大量自噬泡,NC组自噬泡可见部分,miR-184 inhibitors组仅可见极少量自噬泡。(7)MiR-184 mimics组NF-κB、LC3Ⅱ、Beclin1蛋白表达水平显著高于NC组(t=14.055、14.486、28.450,P均<0.001),miR-184inhibitors组NF-κB、LC3Ⅱ、Beclin1蛋白表达水平显著低于NC组(t=15.423、10.354、39.836,P均<0.001)。[结论]MiR-184可在一定程度上抑制胃癌细胞的侵袭和增殖能力,其主要作用机制是诱导胃癌细胞的自噬与凋亡。     

microRNA-155 is downregulated in gastric cancer cells and involved in cell metastasis

microRNA-155 (miR-155), an important multifunctional microRNA, has been implicated in the development of multiple solid tumors, yet, its role in gastric cancer cells has not been fully elucidated. In this study, we find that miR-155 was significantly downregulated in gastric cancer cell lines compared with an immortalized gastric epithelial cell line (GES-1). Overexpression of miR-155 in SGC-7901 and MKN-45 gastric cancer cells dramatically suppressed cell migration, invasion and adhesion in vitro. Overexpression of miR-155 significantly reduced the protein levels of SMAD2 and repressed the activity of a luciferase reporter containing one of the two predicted miR-155 binding sites in SMAD2 3'-UTR, indicating that SMAD2 may be a miR-155 target gene. miR-155 expression was also remarkably restored by a DNA demethylating agent (5-Aza-2-deoxycytidine) in SGC-7901 and MKN-45 gastric cancer cells. Taken together, these data suggest that miR-155 may function as a tumor suppressor to regulate gastric cancer cell metastasis by targeting SMAD2, and its downregulation in gastric cancer cells may be partly ascribed to DNA methylation.     

Expression and regulatory function of miRNA-34a in targeting survivin in gastric cancer cells

We aimed to investigate the expression of microRNA-34a (miR-34a) in human gastric cancer cells and to evaluate the effects of miR-34a, acting via its gene survivin, on gastric cancer cell HGC-27 to provide potential new strategies for treating gastric cancer. In vitro cultures of the human gastric cancer cell lines MGC80-3, HGC-27, NCI-N87, and SGC-7901 and the normal human gastric epithelial cell line GES-1 were established. The expression of miR-34a in each gastric cancer cell line and GES-1 normal human gastric epithelial cell line was detected using quantitative real-time polymerase chain reaction (qRT-PCR). After the HGC-27 cells were transfected with a miR-34a mimic for 48 h, the changes in the expression levels of miR-34a were detected using qRT-PCR. The effect of miR-34a on HGC-27 cell viability was measured using a tetrazolium-based colorimetric [?(4,5)-dimethylthiahiazo-(?z-y1)-3,5-di-phenytetrazoliumromide (MTT)] assay. Flow cytometry was used to analyze the effects of miR-34a on HGC-27 cell proliferation. Annexin V/propidium iodide double staining and flow cytometry were used to analyze the effects of miR-34a on HGC-27 cell apoptosis. A Transwell invasion chamber was used to detect the effects of miR-34a on HGC-27 cell invasion. Finally, western blotting was used to analyze the effects of miR-34a on survivin protein expression. The qRT-PCR test determined that miR-34a expression in gastric cancer cells was significantly reduced compared to the normal gastric epithelial cell line GES-1 (p?<?0.01). Compared to the control group, cellular miR-34a expression levels were significantly increased in HGC-27 human gastric carcinoma cells after transfection with a miR-34a mimic for 48 h (p?<?0.01). The MTT assay demonstrated that after overexpressing miR-34a in HGC-27 cells, cellular viability was significantly reduced (p?<?0.05). Flow cytometry analysis determined that upon miR-34a overexpression, the proliferation index decreased significantly (p?<?0.05), and cellular apoptosis was significantly increased (p?<?0.01). The Transwell invasion chamber assay illustrated that after increasing the expression of miR-34a, the number of cells passing through the Transwell chamber was significantly reduced (p?<?0.01). Based on western blotting, compared with the control group, survivin protein expression levels were significantly decreased in the HGC-27 cells transfected with the miR-34a mimic for 48 h (p?<?0.01). In conclusion, the expression level of miR-34a was downregulated in human gastric cancer cell lines. miR-34a can negatively regulate survivin protein expression and inhibit gastric cancer cell proliferation and invasion. Therapeutically enhancing miR-34a expression or silencing the survivin gene may benefit patients with gastric cancer.     

Smac基因过表达对胃癌细胞株 MKN-45 化疗敏感性的影响

背景与目的:细胞凋亡异常是肿瘤细胞产生耐药性的关键因素之一. Smac(second mitochondria-derived activator of caspases,Smac或称 DIABLO)是新近发现的一种凋亡调节基因,在介导化疗药物诱导肿瘤细胞凋亡中起重要作用.本研究旨在观察 Smac基因过表达对胃癌细胞株化疗敏感性的影响.方法:采用脂质体 GeneSHUTTLE-40介导的方法,将 Smac基因转入胃癌细胞 MKN-45, RT-PCR和 Western blot法检测癌细胞中 Smac的表达;选用顺铂 (1、 5、 10 μ g/ml)、丝裂霉素 (0.1、 1、 10 μ g/ml)和姜黄素 (10、 20、 40 μ mol/L)分别处理转染前后的胃癌细胞,四甲基偶氮唑蓝( MTT)比色法检测细胞增殖活性,倒置显微镜下观察细胞形态变化并摄影, Annexin V-FITC和碘化丙啶双染色,流式细胞仪检测细胞凋亡.结果:同未转染对照组比较,转染外源性 Smac基因后 MKN-45细胞 Smac mRNA和蛋白表达水平显著增高( P< 0.01);各浓度顺铂、丝裂霉素和姜黄素处理 24 h后,细胞生长抑制率分别 增加 10.10%～ 23.80%( P< 0.01)、 10.01%～ 15.86%( P< 0.01)、 11.28%～ 22.12%( P< 0.01),细胞明显变圆、折光增强、漂浮细胞增多,细胞凋亡率分别增加 6.7%～ 20.2%( P< 0.01)、 5.4%～ 13.2%( P< 0.01)、 10.6%～ 20.1%( P< 0.01).结论:转染外源性 Smac基因并使其在胃癌细胞中过表达,能提高 MKN-45对化疗药物的敏感性.