miR-200b通过靶向PROM1抑制胶质瘤细胞侵袭

目的 探讨miR-200b靶向调控PROM1的表达对胶质瘤细胞侵袭能力的影响以及miR-200b抑瘤的分子机制.方法 构建PROM1 3’端非翻译区(3'UTR)荧光素酶报告载体,荧光素酶报告检测miR-200b对PROM1 3'UTR-荧光素酶活性的影响.将miR-200b模拟物转染胶质瘤U87细胞,采用实时荧光定量PCR和Western blot检测PROM1 mRNA和蛋白的表达水平.将PROM1 siRNA转染U87细胞,Transwell侵袭实验检测PROM1下调对U87细胞侵袭能力的影响.结果 双荧光素酶报告检测显示,miR-200b能特异性地与PROM1 3'UTR结合,抑制其荧光素酶活性,其荧光素酶活性强度下降了57.0％,差异有统计学意义(P＜0.01).过表达miR-200b的U87细胞中PROM1蛋白和mRNA表达水平均降低,转染miR-200b组和对照组中PROM1 mRNA的表达水平分别为0.64 ±0.05和0.95 ±0.09,差异有统计学意义(P＜0.05).siRNA于扰PROM1表达能抑制U87细胞的生长和侵袭能力.转染PROM1siRNA组和对照组中穿膜细胞数分别为(85±9)个和(155±16)个,差异有统计学意义(P＜0.05).结论 miR-200b可通过靶向调控PROM1的表达而抑制胶质瘤细胞的侵袭力.     

胃癌组织中miR-200a、miR-200b和miR-429的表达及临床意义北大核心CSCD

0 引言 胃癌是消化系统常见恶性肿瘤之一,2006年中国肿瘤发病和死亡资料分析显示,无论城市还是农村,胃癌的发病率和死亡率均居恶性肿瘤第二位,已成为我国今后恶性肿瘤防控的重点[1]。目前,胃癌的病因尚不明确,加之滞后的临床表现和诊断,以手术为主、放化疗为辅的综合治疗手段亦未能显著提高患者的5年生存率[2]。所以,探寻胃癌新特异性的分子标志物,为其早期诊断开辟新途径具有重要意义。     

缓激肽选择性调节血肿瘤屏障机制

在脑肿瘤中,血肿瘤屏障（blood tumor barrier,BTB）比血脑屏障（blood brain barrier,BBB）有更高的通忑透性,但是BTB的存在仍然明显限制抗肿瘤药物进入肿瘤组织内。常规化疗失败的主要原因是没有足够数量的抗肿瘤药物进入肿瘤组织内。研究表明,给予劲内动脉灌注小剂量缓激肽可以选择性开放BTB,而不影响正常脑组织。这为临床联合使用BK和化疗治疗脑肿瘤提供了依据。本文试图从细胞旁途径和跨细胞途径综述缓激肽（BK）影响BTB通透性的机制。     

miR-193b与肿瘤相关性的研究进展

miRNAs已被证实是基因表达的关键调控因子,不同水平的表达与各种疾病相关。大多数的研究表明,miRNAs表达谱中的miR-193b参与机体多种病理生理过程,在肿瘤发生、发展过程中发挥抑癌基因的作用,可抑制肿瘤细胞增殖、迁移和侵袭能力。因此,miR-193b在疾病的诊断、治疗和预后评估等方面将会发挥更大的作用,有着广阔的应用前景。本文就miR-193b与肿瘤相关性研究进展作一综述。     

miR-200c与肿瘤进展关系的研究进展

microRNA（miRNA）是内源性非编码单链小RNA,参与细胞增殖、凋亡与分化等多种重要生命活动的调控。近年来研究发现,miRNAs参与多种恶性肿瘤的演进,起抑癌基因或原癌基因的作用。miR-200c是上皮-间质转化（epithelial-mesenchymal, EMT)过程中的重要调节基因,除了在正常细胞的表型转换中起作用,还在多种类型癌细胞的表型转换中起调节作用,能促进或者抑制肿瘤的侵袭转移能力。此外,关于miR-200c的研究还涉及肿瘤的耐药性和凋亡抗性。研究证实,miR-200c能够促进或抑制肿瘤的侵袭转移,逆转肿瘤细胞的耐药性和凋亡抗性。本文主要对不同肿瘤中miR-200c对肿瘤进展的影响进行综述。     

miR-199b在肿瘤中研究的新进展

MicroRNA是一类内源性非编码小RNA,它通过部分或完全互补与mRNA结合引起mRNA降解或翻译抑制从而导致靶基因表达受抑。研究发现miR-199b表达水平的异常与多种疾病有关,尤其是在肿瘤的发生、发展、转移、侵袭等过程中具有重要意义。miR-199b在一些肿瘤中很可能成为诊断肿瘤的标志物,而且还可能为治疗肿瘤提供新靶点。本文主要对miR-199b在各种肿瘤中的作用及其机制加以阐述。     

上皮细胞间质转化与miR-200及肿瘤细胞耐药机制的研究进展

目的:总结国内外上皮细胞间质转化与miR-200家族及肿瘤细胞耐药中的研究进展.方法:应用PubMed、CNKI及维普数据库以“EMT、miR-200和肿瘤耐药”为关键词,检索2000-2012年相关文献.共检索到英文文献5 789条,中文文献9条.纳入标准:1)上皮细胞间质转化的特性与功能;2)miR-200家族成员主要功能;3)EMT及miR-200与肿瘤耐药的关系;4)针对EMT及miR-200为靶点进行逆转肿瘤细胞耐药性的研究.根据纳入标准符合分析的文献共54篇.结果:EMT同诱导肿瘤细胞侵袭性改变以及获得性耐药的发生息息相关,miR-200家族在肿瘤细胞中的表达下调同样可以导致肿瘤耐药形成,且EMT与miR-200间可能存在一定联系,以EMT与miR-200为靶点逆转肿瘤细胞耐药性取得一定成效.结论:上皮细胞间质转化与miR-200在诱导肿瘤细胞耐药机制中有着重要作用,从两者入手是解决肿瘤细胞获得性耐药的可能途径.     

miR-200与肿瘤侵袭转移关系的研究进展

微小RNA(microRNA,miRNA)可以互补结合到与肿瘤细胞侵袭转移相关的癌基因或抑癌基因上,抑制或沉默相应基因的表达,导致肿瘤细胞侵袭转移活性的改变。目前,已有多项研究表明miR-200家族参与肿瘤细胞侵袭转移的调节。本文就miR-200家族与肿瘤细胞侵袭转移关系的研究进展做一综述。     

miR 133b与肿瘤的关系及其作用机制

microRNA(miRNA)是一类长度为20~24个核苷酸的非编码小RNA,它们可在转录后水平调节基因的表达。miRNA是许多细胞功能调控的关键因素,包括细胞的生长、增殖、分化及凋亡等。近来许多研究发现miR-133b与肿瘤的侵袭与转移密切相关,它可以通过抑制EGFR、fas、FSCN1及c-MET等多种基因的表达而发挥其抗肿瘤作用。本文主要对miR-133b在不同肿瘤中的异常表达及其可能的作用及其作用机制进行综述。     

miRNA-200b在上皮来源恶性肿瘤中的研究进展

microRNA是机体内源性表达的长度为18~25个核苷酸的非编码单链小分子RNA。通过完全或不完全互补的方式与靶基因结合并使其mRNA裂解或抑制其蛋白翻译,进而在转录后水平调控靶基因的表达,已经作为基因表达的强力调控因子成为肿瘤领域的研究热点。近年来,miR-200家族在上皮来源恶性肿瘤中的表达和功能研究逐渐成为焦点,如研究其在肿瘤细胞增殖、侵袭转移等方面的作用机制和靶点。miRNA-200b是miRNA-200家族具有代表性的一员,本文对miRNA-200b结构特点、作用机制及其在多种上皮来源肿瘤中的研究情况进行综述。      

冰片对血脑肿瘤屏障开放程度及紧密连接蛋白表达的影响

目的：探讨冰片对血脑肿瘤屏障（BTB）开放程度和紧密连接蛋白表达的影响。方法建立体外BTB试验模型,分为空白对照组（培养基）、冰片低剂量组（25μg/ml）、冰片中剂量组（50μg/ml）、冰片高剂量组（100μg/ml）。采用辣根过氧化酶（HRP）流量和酶联免疫吸附法（ELISA）测定不同时间点BTB的通透性及紧密连接相关蛋白的表达。结果随着时间延长,低、中、高剂量组各时间点通透率均逐渐升高（P﹤0.01）;低、中、高剂量组10～240 min通透率高于空白组（P﹤0.01）;中、高剂量组30～180 min通透率高于低剂量组（P﹤0.05）;高剂量组10～180 min通透率高于中剂量组（P﹤0.05）;不同时间点间和不同组别间Occludin蛋白表达水平比较,差异均无统计学意义（P﹥0.05）;各组ZO-1和F-actin蛋白表达量均先降低后逐渐升高（P﹤0.05）;低剂量组30 min后,中、高剂量组60 min后蛋白表达量缓慢上升,且均至240 min时基本与给药前水平一致（P﹥0.05）;中、高剂量组在30、60 min时ZO-1和F-actin蛋白表达量最低（P﹤0.01）,并存在剂量依赖趋势,即高剂量﹤中剂量﹤低剂量﹤给药前。结论冰片可以增加BTB的开放程度,从而提高化疗药物的透过率,其机制可能是通过调控紧密连接蛋白ZO-1和F-actin的表达而实现的。     

血清miRNA-200b在非小细胞肺癌中的表达及其临床意义

目的 探究血清miRNA-200b在非小细胞肺癌(NSCLC)患者中的表达水平.方法 选择45例NSCLC患者为观察组,同时选取30例经诊断无肿瘤疾病的健康对照组.qRT-PCR检测各组血清miRNA-200b的表达水平.结果 观察组患者miRNA-200b血清表达水平明显高于对照组(P＜0.0001).观察组患者血清miRNA-200b水平随着临床分期的升高而显著上升(P＜0.05);另外,NSCLC患者中肺鳞癌患者血清miRNA-200b表达显著高于腺癌(P＜0.0001).此外,ROC分析miRNA-200b诊断NSCLC最佳cutoff值为0.276(敏感性46.7％,特异性93.3％,AUC值0.779).结论 NSCLC患者血清miRNA-200b水平显著升高,在NSCLC患者的疾病发展过程中起到重要的作用,可作为无创早期诊断NSCLC的指标之一.     

MiR-200b regulates autophagy associated with chemoresistance in human lung adenocarcinoma

Chemoresistance remains a major clinical problem in combating human lung adenocarcinoma (LAD), and abnormal autophagy is closely associated with this phenomenon. In the present study, an inverse correlation between miR-200b and autophagy-associated gene 12 (ATG12) expressions was observed in docetaxel-resistant (SPC-A1/DTX and H1299/DTX) and sensitive (SPC-A1 and H1299) LAD cells as well as in tissue samples. Further study showed that miR-200b directly targeted ATG12 in LAD. Moreover, miR-200b-dependent ATG12 downregulation inhibited autophagy and enhanced the chemosensitivity of SPC-A1/DTX and H1299/DTX cells both in vivo and in vitro. LAD chemoresistance is therefore closely related to downregulation of miR-200b and the corresponding upregulation of ATG12. These results provide new evidence for the mechanisms governing the microRNA (miRNA)-ATG12 network and their possible contribution to autophagy modulation and LAD chemoresistance.     

CCL5 promotes VEGF-dependent angiogenesis by down-regulating miR-200b through PI3K/Akt signaling pathway in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignant bone cancer, with potential for local invasion and distant metastasis. Chemokine CCL5 (formerly RANTES) of the CC-chemokine family plays a crucial role in metastasis. Angiogenesis is essential for the cancer metastasis. However, correlation of CCL5 with vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma is still unknown. CCL5-mediated VEGF expression was assessed by qPCR, ELISA, and Western blotting. CCL5-induced angiogenesis was examined by migration and tube formation in endothelial progenitor cells in vitro. CCL5 increased VEGF expression and also promoted chondrosarcoma conditional medium-mediated angiogenesis in vitro and in vivo. Stimulation of chondrosarcoma with CCL5 augmented PI3K and Akt phosphorylation, while PI3K and Akt inhibitor or siRNA abolished CCL5-induced VEGF expression and angiogenesis. We also demonstrated CCL5 inhibiting miR-200b expression and miR-200b mimic reversing the CCL5-enhanced VEGF expression and angiogenesis. Moreover, in chondrosarcoma patients showed the positive correlation between CCL5 and VEGF; negative correlation between CCL5 and miR-200b. Taken together, results demonstrate CCL5 promoting VEGF-dependent angiogenesis in human chondrosarcoma cells by down-regulating miR-200b through PI3K/Akt signaling pathway.     

HDAC 1/4-mediated silencing of microRNA-200b promotes chemoresistance in human lung adenocarcinoma cells

Chemoresistance is one of the most significant obstacles in lung adenocarcinoma (LAD) treatment, and this process involves genetic and epigenetic dysregulation of chemoresistance-related genes. Previously, we have shown that restoration of microRNA (miR)-200b significantly reverses chemoresistance of human LAD cells by targeting E2F3. However, the molecular mechanisms involved in the silencing of miR-200b are still unclear. Here we showed that histone deacetylase (HDAC) inhibitors could restore the expression of miR-200b and reverse chemoresistant phenotypes of docetaxel-resistant LAD cells. HDAC1/4 repression significantly increased miR-200b expression by upregulating histone-H3 acetylation level at the two miR-200b promoters partially via a Sp1-dependent pathway. Furthermore, silencing of HDAC1/4 suppressed cell proliferation, promoted cell apoptosis, induced G₂/M cell cycle arrest and ultimately reversed in vitro and in vivo chemoresistance of docetaxel-resistant LAD cells, at least partially in a miR-200b-dependent manner. HDAC1/4 suppression-induced rescue of miR-200b contributed to downregulation of E2F3, survivin and Aurora-A, and upregulation of cleaved-caspase-3. HDAC1/4 levels in docetaxel-insensitive human LAD tissues, inversely correlated with miR-200b, were upregulated compared with docetaxel-sensitive tissues. Taken together, our findings suggest that the HDAC1/4/Sp1/miR-200b/E2F3 pathway is responsible for chemoresistance of docetaxel-resistant LAD cells.     

Plasma miR-200b in ovarian carcinoma patients: distinct pattern of pre/post-treatment variation compared to CA-125 and potential for prediction of progression-free survival

Ovarian carcinomas (OvCa) are highly heterogeneous malignancies. We investigated four circulating plasma microRNAs (miR-21, miR-34a, miR-200b and miR-205) as candidate biomarkers. Using qPCR, we assessed the plasma concentration of these markers in 101 women, including 51 previously untreated OvCa patients, 25 healthy women and 25 patients bearing benign pelvic lesions. For a subset of 33 OvCa patients, the assay was repeated at the end of the primary treatment. The pattern of variations (post- minus pre-treatment) of concentration was compared to that of CA-125. A Cox regression model was used to study the association between variations and the progression-free survival (PFS). Plasma miR-200b proved to have a greater average concentration in OvCa samples (median 2^−ΔΔCt = 15.18) than in samples linked to non-malignant lesions (median 2^−ΔΔCt = 1.26, p-value = 0.0004). Its concentration was highly heterogeneous among OvCa patients, without any correlations with the FIGO stage and the pre-treatment CA-125 level. The decrease in CA-125 concentration was constant and often dramatic, while the variations of miR-200b concentration were much more diverse. The variation of miR-200b was marginally associated with the PFS (hazard ratio=2.95 95%CI=[0.94; 9.28], p=0.06) while miR-200b as a continuous time-dependent variable was significantly associated (HR=1.06 [1.02; 1.10], p=0.003). This study is the first direct empirical evidence that miR-200b can provide additional information, independent of CA-125 in OvCa patients.     

肾透明细胞癌中miR-200c负性调控ZEB2基因表达的机制研究

目的:探讨肾透明细胞癌中miR-200c调控ZEB2基因表达的分子机制。方法:实时定量PCR法检测肾透明细胞癌及癌旁组织中miR-200c及ZEB2基因的表达水平。培养肾透明细胞癌Caki-1细胞,将miR-200c的前体转染Caki-1细胞,Western blot法检测ZEB2蛋白的表达改变,荧光素酶报告基因表达分析实验验证miR-200c与ZEB2基因的3' 非翻译区(3' UTR)的结合及调控作用。结果:实时定量PCR表达检测显示,与癌旁组织相比,miR-200c在肾透明细胞癌组织中的表达显著下调,而ZEB2 mRNA在肾透明细胞癌组织中的表达则呈现明显上调。Pearson相关性分析结果表明,在肾透明细胞癌及癌旁组织中miR-200c与ZEB2基因的表达均显示负性相关。荧光素酶报告基因表达分析实验明确miR-200c能够与ZEB2基因的3' UTR特异性地结合,并抑制荧光素酶的表达。miR-200c前体能够显著下调Caki-1细胞中ZEB2蛋白的表达。结论:miR-200c与ZEB2基因的表达异常与肾透明细胞癌相关,在肾透明细胞癌细胞中miR-200c能够负性调节其靶基因ZEB2的表达。     

钙激活性钾通道在缓激肽选择性开放血脑肿瘤屏障机制中的大鼠在体研究

目的:探讨钙激活性钾通道(calciumactivatedpotassiumchannel,KCa)在缓激肽(bradykininBK)选择性开放血脑肿瘤屏障(bloodbraintumorbarrier,BTB)中的作用。方法:建立大鼠脑胶质瘤模型,颈内动脉分别灌注BK、KCa通道激动剂NS1619以及灌注BK后再灌注KCa通道阻断剂IBTX,取肿瘤标本电镜观察毛细血管内皮细胞的变化;颈内动脉灌注BK后采用免疫组化ABC法和Westernblot法测定肿瘤组织KCa通道蛋白的分布和含量的变化。结果:大鼠脑胶质瘤模型经颈内动脉分别灌注BK和NS1619后,肿瘤毛细血管内皮细胞的吞饮小泡增加,依次灌注BK和IBTX后,未观察到肿瘤毛细血管内皮细胞的吞饮小泡增加;脑胶质瘤大鼠模型经颈内动脉灌注BK后,其肿瘤内血管内皮细胞的KCa通道蛋白增加,且灌注后10min增加最为显著。结论:KCa通道蛋白的表达增多可能是BK选择性开放BTB机制中的重要因素之一。