microRNA-125b 抑制结肠癌细胞增殖的研究

目的:探究在多种肿瘤中均发挥重要调节作用的miR-125b对结肠癌细胞增殖的影响。方法:采用miR-125b过表达的结肠癌细胞系HCT116,在细胞水平验证miR-125b对细胞增殖能力的影响。采用皮下注射的方式,建立裸鼠结肠癌皮下移植瘤模型,以研究miR-125b对结肠癌体内增殖的影响。在临床样本组织中检测miR-125b的表达以佐证miR-125b功能。结果:在体外MTT实验中,miR-125b能够抑制结肠癌细胞系HCT116的增殖(P0.001)。在体内模型中,注射过表达miR-125b mimics的HCT116细胞所形成的肿瘤与对照组相比,生长速度缓慢,肿瘤大小亦明显低于对照组(P0.05)。在临床样本中对比癌组织与癌旁正常组织中miR-125b的表达量,发现miR-125b在癌旁组织中表达明显高于癌组织。结论:miR-125b能够抑制结肠癌细胞的增殖。     

miRNA-125b在膀胱癌中的表达和意义

目的:探讨膀胱癌组织中miR-125b的表达在膀胱癌发生发展中的作用及其临床意义。方法:采用应用茎环RT-PCR的方法检测66例膀胱尿路上皮癌组织标本的miR-125b的表达,另有16例正常膀胱黏膜组织作对照,并结合临床病理资料进行统计学分析。结果:miR-125b在膀胱癌组织中的表达显著高于非肿瘤的正常膀胱黏膜组织(p0.05),miR-125b的水平还与表达水平与膀胱癌的组织学分级、肿瘤转移、术后复发均明显相关性(P0.05)。结论:miR-125b在膀胱癌组织中表达量升高,且与组织学分级、肿瘤转移、术后复发相关,可能作为膀胱癌诊断和预后指标。     

微小分子miR-125b新靶基因的鉴定及其功能初步研究

目的:利用生物信息学方法预测miR-125b的新靶基因,在肝癌细胞系中进行验证和结合位点的鉴定,为阐明miR-125b在肝癌发生发展中的作用和机制提供新线索。方法:Western印迹分析在肝癌细胞中过表达miR-125b后上皮-间充质转化(EMT)相关蛋白的表达情况;对肝癌患者肿瘤组织及癌旁组织的miR-125b表达差异进行实时定量PCR检测,同时对SNAIL1的表达情况进行免疫组化检测;用生物信息学方法预测miR-125b的新靶基因;利用双萤光素酶报告系统验证miR-125b在预测的新靶基因mRNA的3'非翻译区是否有直接结合位点;构建新靶基因的真核过表达载体,检测新靶基因过表达后对miR-125b表达水平的影响。结果:在肝癌细胞中过表达miR-125b可抑制细胞EMT过程,下调α平滑肌肌动蛋白、神经钙黏素的表达;miR-125b在肝癌患者肿瘤组织中的表达远低于癌旁组织,而SNAIL1作为调控EMT的主要转录因子之一,其在肿瘤组织中的入核比例明显高于癌旁组织;用TargetScan预测到snail1是miR-125b的潜在靶点之一,但双萤光素酶实验表明snail1并非miR-125b的直接靶基因。此外,我们意外发现在肝癌细胞中过表达SNAIL1可上调miR-125b的表达。结论:miR-125b可抑制肝癌EMT过程,但并非直接通过靶向snail1发挥作用,两者在肝癌细胞中存在着复杂的间接调控关系。     

c-MYC调节的miRNA-92b在结直肠癌发生发展中的功能及机制探究（英文）

micro RNAs(miRNAs)在参与癌症发生、发展过程中起着十分重要的作用.目前,miR-92b在结直肠癌中的作用及相关机制还未见报道.本研究探讨了miR-92b在结直肠癌发生发展中的功能及潜在机制.采用RT-qPCR方法发现,miR-92b在人结直肠癌临床样本中与癌旁组织相比显著高表达.通过结肠癌细胞株SW620稳转细胞及裸鼠皮下成瘤模型,发现过表达miR-92b可以显著促进细胞增殖及体内肿瘤生长.同时还发现miR-92b可以分泌形式存在于胞外及外周血中,提示miR-92b是一个具有分泌特性的micro RNA.在分子机理方面,c-MYC可通过调节miR-92b的启动子活性从而促进后者转录,并且c-MYC在结直肠癌组织样本中也存在高表达.进一步,通过在线预测、报告质粒活性检测及蛋白质印迹技术证实FBXW7是一个新的miR-92b靶基因.由于FBXW7已报道为c-MYC泛素降解过程中的关键泛素化连接酶之一,本研究结果提示结直肠癌中c-MYC、miR-92b及FBXW7三者间可能存在分子调节环路.综上所述,本研究为miR-92b在结直肠癌中的功能及机制提供了新的视角,并为miR-92b在结直肠癌早期诊断中的应用提供了新的参考.     

过表达微小RNA miR-125b抑制肝癌细胞上皮-间质转换及促进细胞凋亡

微小RNA-125b（miR-125b）在许多恶性肿瘤的增殖、分化和凋亡等过程中具有很重要的作用,但miR-125b是否涉及肝癌的上皮 间质转换过程（EMT）还有待进一步研究。本研究通过构建过表达miR-125b的肝癌稳转细胞株,初步检测miR-125b对于肝癌的EMT过程和相关的TGF-β信号通路的影响,以及对于肝癌细胞凋亡的影响。以慢病毒载体pHRS-1cla EGFP 构建过表达miR-125b的载体质粒(pHRS-1cla-miR125b-CMV-EGFP),并对上述载体进行NheⅠ、XbaⅠ双酶切和测序鉴定,鉴定正确后,在293T细胞中进行慢病毒包装,浓缩病毒后,对MHCC97-H进行慢病毒感染并采用流式分选GFP阳性的细胞。实时定量PCR检测表明肝癌细胞稳转株MHCC97-H-PHRS-miR-125b-EGFP的miR-125b表达量是空载体转染组的6倍。Western印迹检测发现,与空载体对照组相比,MHCC97-H-PHRS-miR-125b-EGFP细胞中间质细胞标志α-SMA表达显著下调,上皮细胞标志E-cadherin表达显著上调,同样的,用Western印迹检测也发现MHCC97-H-PHRS-miR-125b-EGFP细胞中TGF-β信号通路关键下游分子Smad2和Smad4的表达显著下调,细胞凋亡检测结果表明,与对照组相比,过表达miR-125b的稳转株凋亡率增加到19.66%,加入TGF-β1后,过表达miR-125b的稳转株凋亡率进一步增加到74.7%。同样的,在体内治疗实验中,我们采用商品化的体内核酸转染试剂,在皮下肿瘤组织中过表达miR-125b mimics,结果表明miR-125b的过表达与肿瘤组织的凋亡成正相关性（r=0.83463,P < 0.01）,且免疫组化结果也表明,miR-125b过表达后,E-cadherin表达显著上调,α-SMA及Smad2和Smad4的表达显著下调。上述结果表明,我们成功构建了过表达miR-125b的肝癌细胞稳转株,并成功建立了肿瘤组织中过表达miR-125b mimics的动物模型,在体内外均观察到过表达miR-125b后对肝癌细胞EMT过程的抑制作用和对细胞凋亡的促进作用。相关研究结果加深了我们对miR-125b在肝癌中抑制肝癌发展作用机制的理解,及其作为潜在的治疗肝癌的新靶点的重要性。     

miR-125b在前列腺癌1E8细胞运动转移中的作用及其分子机制的初步探讨

目的 研究 miR-125b在前列腺癌高低转移潜能细胞中的表达差异及其对高转移细胞株1E8细胞的运动转移中的作用和可能的分子机制.方法 realtime PCR法检测前列腺癌高低转移潜能配对细胞系中 miR-125b的表达差异.通过划痕实验及transwell实验观察1E8细胞及转染 miR-125b 抑制剂及其阴性对照后该细胞运动转移能力的变化.结果 realtime PCR结果显示高转移潜能1E8细胞中miR-125b表达水明显高于低转移潜能2B4细胞;下调miR-125b会减弱1E8细胞的运动转移能力.结论 miR-125b可促进前列腺癌细胞的运动转移能力.     

MiR-26b是前列腺癌中的抑癌微RNA（英文）

微RNAs(又称miRNAs或miRs)是一类长度为19~24个核苷酸的单链非编码RNA分子.miRNA通过与其靶向的mRNA分子序列特异性互补配对,调节mRNA表达水平,抑制转录后的蛋白质翻译.miRNA在肿瘤中既可作为致癌因子也可作为抑癌因子.本研究前期已报道miR-26b在前列腺癌细胞系中低表达,并且抑制细胞自噬.本研究进一步全面揭示miR-26b对前列腺肿瘤细胞的作用.我们发现过表达miR-26b能够在体外抑制前列腺癌细胞的增殖和侵袭,并抑制裸鼠体内原位异种前列腺肿瘤的生长.为了探究miR-26b对前列腺癌细胞增殖和侵袭的潜在调控机制,我们进行了表达谱芯片鉴定miR-26b调控基因.表达谱芯片分析表明,在前列腺癌细胞系PC-3中过表达miR-26b后,显著上调的基因57个,显著下调的基因55个(变化倍数均大于2,且P值小于0.05).差异基因的功能多与细胞增殖、凋亡调控、蛋白质磷酸化和泛素化修饰调控过程相关,并且富集在多种信号通路中,例如TNF和TGF-β信号通路.在这些筛选出的基因中,CEACAM6表达水平下调2.17倍;序列分析及实验验证表明,CEACAM6的3′UTR区存在miR-26b的互补序列,是miR-26b的直接靶标.本研究证明了miR-26b能够靶向结合抑制CEACAM6的表达,从而抑制前列腺癌细胞在体外和体内的细胞增殖和侵袭活性,miR-26b是前列腺癌中的抑癌microRNA.     

c-MYC调节的miRNA-92b在结直肠癌发生发展中的功能及机制探究

microRNAs(miRNAs)在参与癌症发生、发展过程中起着十分重要的作用．目前,miR-92b在结直肠癌中的作用及相关机制还未见报道．本研究探讨了miR-92b在结直肠癌发生发展中的功能及潜在机制．采用RT-qPCR方法发现,miR-92b在人结直肠癌临床样本中与癌旁组织相比显著高表达．通过结肠癌细胞株SW620稳转细胞及裸鼠皮下成瘤模型,发现过表达miR-92b可以显著促进细胞增殖及体内肿瘤生长．同时还发现miR-92b可以分泌形式存在于胞外及外周血中,提示miR-92b是一个具有分泌特性的microRNA． 在分子机理方面,c-MYC可通过调节miR-92b的启动子活性从而促进后者转录,并且c-MYC在结直肠癌组织样本中也存在高表达．进一步,通过在线预测、报告质粒活性检测及蛋白质印迹技术证实FBXW7是一个新的miR-92b靶基因．由于FBXW7已报道为c-MYC泛素降解过程中的关键泛素化连接酶之一,本研究结果提示结直肠癌中c-MYC、miR-92b及FBXW7三者间可能存在分子调节环路．综上所述,本研究为miR-92b在结直肠癌中的功能及机制提供了新的视角,并为miR-92b在结直肠癌早期诊断中的应用提供了新的参考．     

microRNA-181b通过靶定MLK2调节白血病细胞HL-60的增殖

microRNA在细胞的转移、凋亡、分化等生命过程中发挥着重要的作用. miR-181b在急髓性白血病组织中高表达, 通过靶定MLK2调节急髓性白血病细胞的增殖. 本结果提示, miR-181b在急髓性白血病的生物学过程发挥着重要的作用, 同时为急髓性白血病的治疗提供了新的解决方案.     

miR-155、EMT与肿瘤侵袭转移的研究进展

肿瘤细胞发生上皮间质转化(EMT)是其获得侵袭和转移能力的关键环节之一,而miR-155是EMT的重要调节因子,它通过靶向调节参与这一过程的关键蛋白因子的表达而发挥作用。miR-155的上述功能具有组织和细胞特异性,即在不同的肿瘤组织细胞中它具有促进或抑制侵袭和转移的能力,其功能的发挥取决于其作用靶点的生物学特征。就miR-155与EMT以及肿瘤侵袭转移关系的研究进展作一综述。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.