miR-193a-5p促进人胰腺癌细胞体外迁移和侵袭作用的研究

该研究主要探讨了微小核酸mi RNA-193a-5p对人胰腺癌细胞体外迁移和侵袭的促进作用及其机制。采用miR-193a-5p模拟物及mi R-193a-5p抑制剂分别上调和下调miR-193a-5p的表达;采用细胞划痕法和Transwell小室法检测mi R-193a-5p对细胞迁移和侵袭能力的影响;采用TargetScan 7.1数据库预测miR-193a-5p的靶基因;荧光素酶报告法验证miR-193a-5p的靶基因; Western blot和实时荧光定量PCR验证其表达结果。结果表明, miR-193a-5p可显著促进细胞的迁移和侵袭能力。TargetScan 7.1软件预测, Prox1可能为mi R-193a-5p的靶基因,荧光素酶报告实验显示, miR-193a-5p靶向Prox1基因的3′UTR区。实时荧光定量PCR和Western blot结果显示, miR-193a-5p下调了Prox1的mRNA和蛋白水平的表达。研究结果揭示,在胰腺癌中高表达的miR-193a-5p通过下调Prox1,从而使胰腺癌细胞获得高的迁移和侵袭能力,促进胰腺癌的转移。     

miR-199a-3p/Nme2在TGF-β1信号通路中的作用分析

通过microRNA芯片技术在小鼠GC-1 spg细胞中筛选发现microRNA-199a-3p(miR-199a-3p)受转化生长因子TGF-β1调节。为了进一步探讨二者的关系,通过基因克隆与载体构建技术、双荧光素酶报告基因检测及定量PCR实验,发现miR-199a-3p靶向识别肿瘤转移抑制基因2(Nme2)的3'非编码区(UTR)序列,且正向调控Nme2的表达。利用TGF-β1处理GC-1 spg细胞后,结果显示Nme2和miR-199a-3p在mRNA水平的表达均显著上调;进一步将miR-199a-3p和TGF-β1双重作用于GC-1 spg细胞后,结果表明Nme2的表达会明显增强,而且在TGF-β1通路中,miR-199a-3p被抑制的部分功能可能会被Nme2补偿。综上,miR-199a-3p对Nme2基因具有直接靶向识别和调控作用,且在参与TGF-β1信号通路的生物学效应中,二者在功能上相互关联。     

miR-125a-3p调控人结肠癌细胞浸润转移的作用及机制研究

目的:探讨miR-125a-3p在结肠癌细胞浸润与转移中的作用及其可能机制。方法:通过qRT-PCR方法检测miR-125a-3p在结肠癌细胞及组织样本中的表达;在结肠癌细胞过表达或沉默miR-125a-3p后,通过平板克隆实验、MTT实验、划痕实验、Transwell实验检测结肠癌细胞增殖、迁移及侵袭能力的变化;采用Western blot方法检测miR-125a-3p过表达后相关标志分子的表达水平变化情况。结果:miR-125a-3p在结肠癌细胞及组织呈现异常低表达;过表达miR-125a-3p抑制结肠癌细胞HCT116及SW480的增殖能力;过表达或沉默miR-125a-3p分别抑制或增强结肠癌细胞的迁移与侵袭能力;过表达miR-125a-3p在mRNA及蛋白水平均能够显著抑制Snail、N-cadherin及Vimentin的表达,而增加E-cadherin的表达。结论:miR-125a-3p参与调节结肠癌细胞浸润与转移,其机制可能是通过调控上皮间质转化途径介导的。     

抑制miR-130b-3p通过上调PTEN和灭活PI3K-AKT及整合素β1/FAK信号通路抑制膀胱癌细胞增殖

miR-130家族在癌的进展中发挥作用;然而,其家族成员在膀胱癌中的作用尚罕见报告。本研究证明,抑制miR-130家族成员miR-130b-3p表达促进PTEN表达,诱导细胞凋亡,抑制膀胱癌细胞增殖。首先,我们采用微阵列对来自膀胱癌患者的4对膀胱癌和癌旁组织进行了miRNA和mRNA组学分析,发现miR-130b-3p和miR-106b-3p在膀胱癌组织高表达,而miR-99a-3p、miR-199a-5p和miR-145-3p低表达。RT-q PCR检测30对膀胱癌组织5种miRNA的表达与微阵列中的表达状况一致。此外,我们在mRNA组学分析中还发现,miR-130b-3p在膀胱癌组织的高表达与PTEN表达呈负相关。为此,在后续研究中集中探索了miR-130b-3p在膀胱癌中的作用及其作用机制。生物信息学及荧光素酶报告结果证明,miR-130b-3p可直接结合PTEN的3'-UTR,靶向抑制PTEN的表达。转染结合CCK-8、EDU、流式分析、划痕及Transwell小室实验显示,转染miR-130b-3p模拟物可明显促进膀胱癌T24细胞的增殖、迁移及侵袭能力;相反,转染miR-130b-3p抑制物可明显诱导T24细胞凋亡。鬼笔环肽染色揭示,转染miR-130b-3p模拟物可促进细胞骨架形成,而转染miR-130b-3p抑制物抑制细胞骨架形成。Western印迹证明,转染miR-130b-3p可下调PTEN在T24细胞的表达,上调p-PI3K、p-AKT、p-FAK和整合素β1的表达;而转染miR-130b-3p抑制物上调PTEN的表达,下调p-PI3K、p-AKT、p-FAK和整合素β1的表达。上述结果提示,miR-130b-3p通过抑制PTEN表达,激活PI3K-AKT及整合素β1/FAK信号通路,在膀胱癌中发挥癌基因样作用;相反,抑制miR-130b-3p可上调PTEN表达,抑制PI3K-AKT及整合素β1/FAK信号通路的激活,诱导凋亡,抑制膀胱癌细胞的增殖、迁移和侵袭能力。我们的结果还提示,miR-130b-3p作为可能的临床标志物,对膀胱癌的诊断、靶向治疗具有潜在的应用价值。     

miR-125a-5p通过靶向调控GAB2抑制乳腺癌细胞的迁移能力

miR-125a-5p可负性调节GAB2表达,抑制胶质瘤细胞的侵袭和转移。本研究旨在证明miR-125a-5p抑癌作用的普遍性,即miR-125a-5p是否可通过靶向抑制GAB2抑制乳腺癌细胞的迁移。荧光素酶实验结果显示,miR-125a-5p可特异识别GAB2的3′-UTR,抑制报告酶的表达。荧光定量PCR结果揭示,与正常乳腺上皮细胞MCF-10A比较,miR-125a-5p在乳腺癌细胞MDA231和MCF-7中的表达明显降低;与迁移能力相对较低的MCF-7细胞比较,miR-125a-5p在迁移能力较高的MDA231细胞中的表达量更低。Western 印迹结果证明,与空载体（对照）和anti-miR125a 5p转染细胞比较,转染miR-125a-5p明显抑制GAB2蛋白在乳腺癌细胞中的表达。Transwell结果显示,与空载体转染的对照细胞比较,转染miR-125a-5p的乳腺癌细胞穿过基质胶的细胞数明显减少;相反,转染anti-miR125a-5p的细胞穿过基质胶的细胞数却明显增多。上述结果提示,miR-125a-5p在正常的乳腺细胞中高表达,而在乳腺癌细胞中低表达,其表达水平与癌细胞的迁移能力和GAB2表达呈反向关系。本研究结果还提示,miR-125a-5p通过靶向负调控GAB2抑制乳腺癌细胞的迁移能力。总之,本研究证明,miR-125a-5p在肿瘤中发挥抑癌作用。     

MiR-26b是前列腺癌中的抑癌微RNA

microRNAs（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,抑制转录后的蛋白翻译。miRNA在肿瘤中既可作为致癌因子也可作为抑癌因。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。     

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.     

miR-145靶向调控DAB2对前列腺癌PC3细胞迁移和侵袭能力的影响

已有研究表明, miR-145在多种肿瘤中低表达, 并与细胞增殖和转移相关。文章通过生物信息学分析并结合体外实验鉴定, 发现DAB2(Disabled homolog 2)为miR-145在肿瘤转移过程中累及的新靶点。DAB2一直被认为是一个重要的抑癌基因, 在多种肿瘤标本中表达低下。然而, 研究发现, 在具高侵袭能力的前列腺癌细胞株PC3中DAB2基因却呈较高水平表达。另外, 外源表达miR-145能显著下调 DAB2表达水平, 并抑制PC3细胞的迁移和侵袭能力, 且这种miR-145诱导的PC3细胞功能缺陷能被DAB2过表达修复。上述结果表明, miR-145能通过靶向调控DAB2而影响高侵袭前列腺癌细胞的迁移和侵袭能力。     

circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移

目的 鼻咽癌是一种来源于鼻咽上皮的恶性肿瘤,其临床特征之一是易发生淋巴转移,但是目前鼻咽癌转移的分子机制尚未阐明。circPVT1是由PVT1基因2号外显子反向拼接形成的环状RNA (circRNA),在多种肿瘤中表达上调,本文探讨了circPVT1在鼻咽癌侵袭迁移中的作用和分子机制。方法 通过RT-qPCR检测circPVT1及其下游miRNA和FSCN1在鼻咽癌细胞的表达情况,Transwell和划痕愈合实验检测circPVT1对鼻咽癌细胞侵袭迁移的影响,RNA pull-down实验检测circPVT1结合的miRNA,双荧光素酶报告实验检测miR-24-3p和let-7a-5p靶向抑制FSCN1 mRNA表达。结果 在鼻咽癌细胞中过表达circPVT1可以促进鼻咽癌细胞侵袭迁移,而敲低circPVT1则可以抑制鼻咽癌细胞的侵袭迁移。进一步研究发现,circPVT1可以通过竞争性吸附miR-24-3p和let-7a-5p,上调FSCN1的表达,从而促进鼻咽癌细胞的侵袭迁移。结论 circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移,证实c...     

环状RNA circMRPS35通过miR-130a-3p/ZNRF3轴调节胃癌细胞的增殖、凋亡、迁移和侵袭

摘要 目的：探讨环状RNA MRPS35（circMRPS35）对胃癌（GC）细胞增殖、凋亡、迁移和侵袭的调控机制。方法：体外培养人GC细胞系（HGC-27、MGC-803、MKN45和AGS）和正常胃上皮GES-1细胞,实时荧光定量PCR（RT-qPCR）检测circMRPS35、miR-130a-3p和锌环指蛋白3（ZNRF3）mRNA表达。另取MGC-803细胞,分为对照组、pc-NC组、pc-circMRPS35组、pc-circMRPS35+miR-NC组、pc-circMRPS35+miR-130a-3p组,采用Lipofectamine 3000进行质粒转染。RT-qPCR检测circMRPS35、miR-130a-3p和ZNRF3 mRNA表达,Western blot检测ZNRF3蛋白表达,CCK-8法、流式细胞术检测细胞增殖与凋亡,划痕实验和Transwell小室实验检测细胞迁移与侵袭能力,裸鼠移植瘤实验探究circMRPS35对GC细胞体内生长的影响。双荧光素酶报告基因检测miR-130a-3p与circMRPS35或ZNRF3的靶标关系。结果：GC细胞系中circMRPS35和ZNRF3 mRNA呈低表达,miR-130a-3p呈高表达（均P＜0.05）。过表达circMRPS35可降低miR-130a-3p,上调ZNRF3 mRNA和蛋白水平,抑制细胞增殖、迁移和侵袭,并促进细胞凋亡（均P＜0.05）;circMRPS35过表达对GC细胞恶性行为和裸鼠移植瘤生长的抑制作用可被miR-130a-3p mimic逆转（P＜0.05）。双荧光素酶实验结果显示,过表达miR-130a-3p可降低circMRPS35-WT和ZNRF3-WT的荧光素酶活性（P＜0.05）。结论：circMRPS35可能通过miR-130a-3p/ZNRF3轴抑制GC细胞的增殖、迁移和侵袭,并促进细胞凋亡。     

Novel TGF-β1 inhibitor antagonizes TGF-β1-induced epithelial-mesenchymal transition in human A549 lung cancer cells

Transforming growth factor β1 (TGF-β1), a multifunctional cytokine, is known to promote tumor invasion and metastasis and induce epithelial-mesenchymal transition (EMT) in various cancer cells. Inhibition of TGF-β1 signaling is a new strategy for cancer therapy. Most cancer cells display altered or nonfunctional TGF-β1 signaling; hence, TGF-β1 inhibitors exert limited effects on these cells. Recent studies have suggested that developing a TGF-β1 inhibitor from natural compounds is a key step to create novel therapeutic agents. This study aimed to develop a new anti-TGF-β1 therapy for cancer. We found an improved analog of chalcones, compound 67, and investigated its effects in vitro. We demonstrated the inhibitory role of compound 67 through migration and invasion assays on TGF-β1-induced EMT of human A549 lung cancer cells. Compound 67 inhibited TGF-β1-induced smad2 phosphorylation, suppressed TGF-β1-induced EMT markers, matrix metalloproteinase-2 (MMP-2) and MMP-9, and inhibited migration and invasion of A549 cells. The study results showed that compound 67 is useful to prevent tumor growth and metastasis.     

Upregulation of microRNA-141 suppresses epithelial-mesenchymal transition and lymph node metastasis in laryngeal cancer through HOXC6-dependent TGF-β signaling pathway

Laryngeal cancer is one of the most malignant cancers among the head and neck malignant tumors. Abnormal expression of microRNAs (miRNAs) contributes to cancer development through regulating proliferation and apoptosis of cancer cells. In this study, we aim to explore the roles of microRNA-141 (miR-141), Homeobox C6 (HOXC6) and TGF-β signaling pathway in epithelial-mesenchymal transition (EMT) and lymph node metastasis in laryngeal cancer. Initially, we identified differentially expressed genes in laryngeal cancer, among which HOXC6 was identified. Then the target miRNA of HOXC6 was predicted and verified. Next, expression of miR-141, HOXC6, TGF-β1, Smad3, Vimentin and Snail in cancer tissues was detected. Then, AMC-HN-8 cells were transfected with miR-141 mimic, miR-141 inhibitor and HOXC6-siRNA to investigate specific role of miR-141, HOXC6 and TGF-β signaling pathway in laryngeal cancer in vivo and in vitro. Our results showed that HOXC6 was a target gene of miR-141, which was downregulated in laryngeal cancer. Besides, overexpression of miR-141 could downregulate HOXC6 and inhibit the TGF-β signaling pathway. Upregulation of miR-141 or silencing of HOXC6 can repress EMT, viability, migration and invasion abilities of laryngeal cancer cells. In addition, upregulation of miR-141 inhibited the tumor growth and lymph node metastasis in vivo. In summary, our findings demonstrated that upregulated miR-141 decreased HOXC6 expression, and inhibited the TGF-β signaling pathway, EMT and lymph node metastasis in laryngeal cancer, which is of clinical significance in the treatment of laryngeal cancer.     

Starvation-induced autophagy promotes the invasion and migration of human bladder cancer cells via TGF-β1/Smad3-mediated epithelial-mesenchymal transition activation

The biological characteristics of bladder cancer include enhanced invasion and migration, which are the main causes of death in patients. Starvation is a typical feature of the bladder cancer microenvironment and can induce autophagy. Autophagy has an important relationship with the invasion and migration of tumors. However, the role of autophagy in the invasion and migration of bladder cancer cells remains unclear. Hence, the aim of the current study was to clarify this role and underlying mechanism. In this study, we found that starvation enhanced the epithelial-mesenchymal transition (EMT)-mediated invasion and migration of T24 and 5637 cells while inducing autophagy. The inhibition of autophagy with chloroquine (CQ) or 3-methyladenine (3MA) decreased EMT-mediated invasion and migration. In addition, the expression of transforming growth factor 1 (TGF-β1) and phosphorylated Smad3 (p-Smad3) increased after starvation. The inhibition of autophagy with CQ or 3MA also decreased the expression of TGF-β1 and p-Smad3. The inhibitor of TGF-β receptor sb431542 also inhibited the invasion, migration, and EMT of T24 and 5637 cells during starvation. Furthermore, recombinant TGF-β1 induced autophagy and inhibition of the TGF-β/Smad signaling pathway with sb431542 suppressed autophagy. In summary, our results suggested that autophagy promotes the invasion and migration of bladder cancer cells by inducing EMT through the TGF-β1/Smad3 signaling pathway. Moreover, autophagy and TGF-β1 can form a positive feedback loop to synergistically promote invasion and migration. Thus, our findings may provide a theoretical basis for the prevention of invasion and migration in bladder cancer.     

Mutant p53 disrupts role of ShcA protein in balancing Smad protein-dependent and -independent signaling activity of transforming growth factor-β (TGF-β)

Biomarkers are lacking for identifying the switch of transforming growth factor-β (TGF-β) from tumor-suppressing to tumor-promoting. Mutated p53 (mp53) has been suggested to switch TGF-β to a tumor promoter. However, we found that mp53 does not always promote the oncogenic role of TGF-β. Here, we show that endogenous mp53 knockdown enhanced cell migration and phosphorylation of ERK in DU145 prostate cancer cells. Furthermore, ectopic expression of mp53 in p53-null PC-3 prostate cancer cells enhanced Smad-dependent signaling but inhibited TGF-β-induced cell migration by down-regulating activated ERK. Reactivation of ERK by the expression of its activator, MEK-1, restored TGF-β-induced cell migration. Because TGF-β is known to activate the MAPK/ERK pathway through direct phosphorylation of the adaptor protein ShcA and MAPK/ERK signaling is pivotal to tumor progression, we investigated whether ShcA contributed to mp53-induced ERK inhibition and the conversion of the role of TGF-β during carcinogenesis. We found that mp53 expression led to a decrease of phosphorylated p52ShcA/ERK levels and an increase of phosphorylated Smad levels in a panel of mp53-expressing cancer cell lines and in mammary glands and tumors from mp53 knock-in mice. By manipulating ShcA levels to regulate ERK and Smad signaling in human untransformed and cancer cell lines, we showed that the role of TGF-β in regulating anchorage-dependent and -independent growth and migration can be shifted between growth suppression and migration promotion. Thus, our results for the first time suggest that mp53 disrupts the role of ShcA in balancing the Smad-dependent and -independent signaling activity of TGF-β and that ShcA/ERK signaling is a major pathway regulating the tumor-promoting activity of TGF-β.     

MiR-216a-3p regulates the proliferation,apoptosis, migration,and invasion of lung cancer cells via targeting COPB2

ABSTRACT

Effect of miR-216a-3p on lung cancer hasn’t been investigated. Here, we explored its effects on lung cancer. MiR-216a-3p expression in lung cancer tissues and cells was detected by RT-qPCR. The target gene of miR-216a-3p was predicted by bioinformatics and confirmed by luciferase-reporter assay. After transfection, cell viability, migration, invasion, proliferation, and apoptosis were detected by MTT, scratch, transwell, colony formation, and flow cytometry. The expressions of COPB2 and apoptosis-related factors were detected by RT-qPCR or western blot. MiR-216a-3p was low-expressed and COPB2 was high-expressed in lung cancer tissues and cells. MiR-216a-3p targeted COPB2 and regulated its expression. MiR-216a-3p inhibited lung cancer cell viability, migration, invasion, and proliferation, while promoted apoptosis. Effect of miR-216a-3p on lung cancer was reversed by COPB2. MiR-216a-3p regulated proliferation, apoptosis, migration, and invasion of lung cancer cells via targeting COPB2.     

The miR-27a-3p/USP25 axis participates in the pathogenesis of recurrent miscarriage by inhibiting trophoblast migration and invasion

Insufficient invasion ability of trophoblasts might be associated with the development of recurrent miscarriage (RM). Ubiquitin-specific protease 25 (USP25) can regulate the processes of invasion and migration in different types of cancer cells. However, the effect of USP25 on trophoblasts and its roles in the development of RM are unknown. In this study, we first analyzed the USP25 expression in placental villous tissues from RM patients, and then assessed the roles of USP25 in epithelial-to-mesenchymal transition (EMT), invasion and migration of trophoblasts. Furthermore, bioinformatics prediction and luciferase reporter assay were used to explore the mechanism of microRNA on USP25 expression, and regulation of USP25 expression in trophoblasts was assessed following transfection with microRNA mimics or inhibitor. The results showed that the expression of USP25 in the placental villous tissues was downregulated in RM patients. Knockdown of USP25 suppressed the EMT process, the invasion and migration capability of trophoblast cells, while overexpression of USP25 exhibited opposite results. Mechanistically, miR-27a-3p could regulate USP25 expression by binding to the 3′-untranslated region of USP25 in trophoblasts. Quantitative real-time polymerase chain reaction results found the expression of miR-27a-3p were negatively related to USP25 in RM patients. MiR-27a-3p mimics inhibited but miR-27a-3p inhibitor enhanced the migration and invasion capability of trophoblasts. Furthermore, sh-USP25 counteracted the promotion of invasion and migration mediated by the miR-27a-3p inhibitor. Taken together, these data indicate that USP25 downregulation by miR-27a-3p contributes to the EMT process, thereby inhibiting the migration and invasion of trophoblast cells, and these findings might provide potential biomarkers for RM.     

MIR-99a and MIR-99b modulate TGF-β induced epithelial to mesenchymal plasticity in normal murine mammary gland cells

Epithelial to mesenchymal transition (EMT) is a key process during embryonic development and disease development and progression. During EMT, epithelial cells lose epithelial features and express mesenchymal cell markers, which correlate with increased cell migration and invasion. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that induces EMT in multiple cell types. The TGF-β pathway is regulated by microRNAs (miRNAs), which are small non-coding RNAs regulating the translation of specific messenger RNAs.Herein, we identified mir-99a and mir-99b as two novel TGF-β target miRNA genes, the expression of which increased during TGF-β induced EMT of NMUMG cells. Mir-99a and mir-99b inhibition decreased TGF-β activity by inhibiting SMAD3 phosphorylation, resulting in decreased migration and increased proliferation in response to TGF-β. However, mir-99a and mir-99b inhibition was insufficient to block TGF-β induced EMT of NMUMG cells.Mir-99a and mir-99b over-expression in epithelial NMUMG cells resulted in increased proliferation, migration and fibronectin expression, while E-cadherin and ZO-1 expression were negatively regulated.In conclusion, we identified mir-99a and mir-99b as two novel modulators of TGF-β pathway that alter SMAD3 phosphorylation, in turn altering cell migration and adhesion of mesenchymal NMUMG cells. The effect of mir-99a and mir-99b over-expression on NMUMUG proliferation is dependent upon the epithelial or mesenchymal status of the cells. Our study suggests that mir-99a and mir-99b may function as modulators within a complex network of factors regulating TGF-β induced breast epithelial to mesenchymal transition, as well as proliferation and migration of breast cancer cells, providing a possible target for future translationally oriented studies in this area.