Phosphoglucose isomerase/autocrine motility factor mediates epithelial-mesenchymal transition regulated by miR-200 in breast cancer cells

Phosphoglucose isomerase/autocrine motility factor (PGI/AMF) plays an important role in glycolysis and gluconeogenesis and is associated with invasion and metastasis of cancer cells. We have previously shown its role in the induction of epithelial-mesenchymal transition (EMT) in breast cancer cells, which led to increased aggressiveness; however, the molecular mechanism by which PGI/AMF regulates EMT is not known. Here we show, for the first time, that PGI/AMF overexpression led to an increase in the DNA-binding activity of NF-κB, which, in turn, led to increased expression of ZEB1/ZEB2. The microRNA-200s (miR-200s) miR-200a, miR-200b, and miR-200c are known to negatively regulate the expression of ZEB1/ZEB2, and we found that the expression of miR-200s was lost in PGI/AMF overexpressing MCF-10A cells and in highly invasive MDA-MB-231 cells, which was consistent with increased expression of ZEB1/ZEB2. Moreover, silencing of PGI/AMF expression in MDA-MB-231 cells led to overexpression of miR-200s, which was associated with reversal of EMT phenotype (i.e., mesenchymal-epithelial transition), and these findings were consistent with alterations in the relative expression of epithelial (E-cadherin) and mesenchymal (vimentin, ZEB1, ZEB2) markers and decreased aggressiveness as judged by clonogenic, motility, and invasion assays. Moreover, either reexpression of miR-200 or silencing of PGI/AMF suppressed pulmonary metastases of MDA-MB-231 cells in vivo, and anti-miR-200 treatment in vivo resulted in increased metastases. Collectively, these results suggest a role of miR-200s in PGI/AMF-induced EMT and thus approaches for upregulation of miR-200s could be a novel therapeutic strategy for the treatment of highly invasive breast cancer.     

lncRNA MALAT1/miR-141-3p/ZEB1 分子轴调控胃癌SGC7901 细胞的侵袭、迁移及上皮间质转化

[摘要] 目的：探究lncRNA MALAT1/miR-141-3p/ZEB1 分子轴对胃癌（GC）SGC7901 细胞侵袭、迁移及上皮间质转化（EMT）的调控作用。方法：收集2014 年4 月至2017 年5 月武汉商职医院普外科手术切除的GC组织（非坏死部分）和配对癌旁组织（距肿瘤组织>5 cm）标本38 例,同时选取正常胃上皮细胞GES1 及GC细胞系SGC7901、HGC27、BGC823、MKN45 和MKN28。qPCR实验检测MALAT1、miR-141-3p 在GC组织和细胞系中的表达水平,CCK-8 和Transwell 实验检测敲降MALAT1 对SGC7901 细胞增殖、迁移和侵袭的影响,WB 实验检测ZEB1、E-cadherin、N-cadherin 和Vimentin 的表达情况。双荧光酶素报告基因验证MALAT1、miR-141-3p 和ZEB1 的靶向关系,CCK-8 和Transwell 实验检测MALAT1/miR-141-3p/ZEB1 分子轴对SGC7901 细胞生物学行为的影响。结果：MALAT1 在GC组织和细胞系中高表达（P<0.05 或P<0.01）。敲降MALAT1 显著抑制了SGC7901 细胞增殖、迁移、侵袭及EMT（P<0.05 或P<0.01）;MALAT1 与miR-141-3p、miR-141-3p 与ZEB1 均具有直接靶向关系;进一步研究表明,同时过表达miR-141-3p 和MALAT1 或ZEB1 能够逆转miR-141-3p 对SGC7901 细胞生物学行为的抑制作用。结论：MALAT1通过靶向下调miR-141-3p 对ZEB1 的抑制作用,进而促进SGC7901 细胞侵袭、迁移及EMT。     

Gemcitabine‐induced epithelial‐mesenchymal transition‐like changes sustain chemoresistance of pancreatic cancer cells of mesenchymal‐like phenotype

Growing body of evidence suggests that epithelial‐mesenchymal transition (EMT) is a critical process in tumor progression and chemoresistance in pancreatic cancer (PC). The aim of this study was to analyze the role of EMT‐like changes in acquisition of resistance to gemcitabine in pancreatic cells of the mesenchymal or epithelial phenotype. Therefore, chemoresistant BxPC‐3, Capan‐2, Panc‐1, and MiaPaca‐2 cells were selected by chronic exposure to increasing concentrations of gemcitabine. We show that gemcitabine‐resistant Panc‐1 and MiaPaca‐2 cells of mesenchymal‐like phenotype undergo further EMT‐like molecular changes mediated by ERK‐ZEB‐1 pathway, and that inhibition of ERK1/2 phosphorylation or ZEB‐1 expression resulted in a decrease in chemoresistance. Conversely, gemcitabine‐resistant BxPC‐3 and Capan‐2 cells of epithelial‐like phenotype did not show such typical EMT‐like molecular changes although the expression of the tight junction marker occludin could be found decreased. In pancreatic cancer patients, high ZEB‐1 expression was associated with tumor invasion and tumor budding. In addition, tumor budding was essentially observed in patients treated with neoadjuvant chemotherapy. These findings support the notion that gemcitabine treatment induces EMT‐like changes that sustain invasion and chemoresistance in PC cells.     

The ZEB1/miR-200c feedback loop regulates invasion via actin interacting proteins MYLK and TKS5

Epithelial to mesenchymal transition (EMT) is a developmental process which is aberrantly activated during cancer invasion and metastasis. Elevated expression of EMT-inducers like ZEB1 enables tumor cells to detach from the primary tumor and invade into the surrounding tissue. The main antagonist of ZEB1 in controlling EMT is the microRNA-200 family that is reciprocally linked to ZEB1 in a double negative feedback loop. Here, we further elucidate how the ZEB1/miR-200 feedback loop controls invasion of tumor cells. The process of EMT is attended by major changes in the actin cytoskeleton. Via in silico screening of genes encoding for actin interacting proteins, we identified two novel targets of miR-200c - TKS5 and MYLK (MLCK). Co-expression of both genes with ZEB1 was observed in several cancer cell lines as well as in breast cancer patients and correlated with low miR-200c levels. Depletion of TKS5 or MYLK in breast cancer cells reduced their invasive potential and their ability to form invadopodia. Whereas TKS5 is known to be a major component, we could identify MYLK as a novel player in invadopodia formation. In summary, TKS5 and MYLK represent two mediators of invasive behavior of cancer cells that are regulated by the ZEB1/miR-200 feedback loop.     

RhoGDI2 promotes epithelial-mesenchymal transition via induction of Snail in gastric cancer cells

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression correlates with tumor growth, metastasis, and chemoresistance in gastric cancer. Here, we show that RhoGDI2 functions in the epithelial-mesenchymal transition (EMT), which is responsible for invasiveness during tumor progression. This tumorigenic activity is associated with repression of E-cadherin by RhoGDI2 via upregulation of Snail. Overexpression of RhoGDI2 induced phenotypic changes consistent with EMT in gastric cancer cells, including abnormal epithelial cell morphology, fibroblast-like properties, and reduced intercellular adhesion. RhoGDI2 overexpression also resulted in decreased expression of the epithelial markers E-cadherin and β-catenin and increased expression of the mesenchymal markers vimentin and fibronectin. Importantly, RhoGDI2 overexpression also stimulated the expression of Snail, a repressor of E-cadherin and inducer of EMT, but not other family members such as Slug or Twist. RNA interference-mediated knockdown of Snail expression suppressed RhoGDI2-induced EMT and invasion, confirming that the effect was Snail-specific. These results indicate that RhoGDI2 plays a critical role in tumor progression in gastric cancer through induction of EMT. Targeting RhoGDI2 may thus be a useful strategy to inhibit gastric cancer cell invasion and metastasis.     

miR-30a通过靶向调控ZEB2抑制非小细胞肺癌的迁移与侵袭

目的:探讨miR-30a在非小细胞肺癌(non-small cell lung cancer,NSCLC)细胞中的表达情况及miR-30a在肺癌细胞迁移和侵袭过程中的作用及其机制。方法:采用qRT-PCR检测miR-30a在不同NSCLC细胞株中的表达情况;采用脂质体2000转染miR-30a mimics和E盒结合锌指蛋白2（E-box binding zinc finger protein 2,ZEB2） siRNA;通过qRT-PCR检验miR-30a mimics和ZEB2 siRNA的转染效率及转染后ZEB2 mRNA的表达水平变化;Western blot检测转染miR-30a mimics和ZEB2 siRNA后ZEB2蛋白表达情况;采用双荧光素酶报告实验验证miR-30a和ZEB2的相互作用机制;划痕实验和Transwell小室侵袭实验检测上调miR-30a和干扰ZEB2对A549细胞迁移和侵袭能力的影响。结果:实验结果显示,与正常人支气管上皮细胞相比,在不同NSCLC细胞株中miR-30a的表达呈不同程度下调;NSCLC细胞转染miR-30a mimics和ZEB2 siRNA后均获得满意的转染效果:miR-30a mimics和ZEB2 siRNA明显降低了NSCLC细胞中ZEB2的mRNA和蛋白的表达水平,组间差异具有统计学意义。双荧光素酶报告实验验证miR-30a对ZEB2 3' UTR具有直接调控作用。细胞迁移实验和侵袭实验结果显示,与Blank组和NC组相比,miR-30a过表达组和ZEB2基因沉默组的A549细胞迁移和侵袭能力均明显降低,说明miR-30a mimics和ZEB2 siRNA均对A549细胞细胞迁移和侵袭有抑制作用。结论:上调miR-30a的表达水平可以负调控ZEB2转录后表达水平,通过抑制上皮-间质转化(epithelial-mesenchymal transition,EMT)的进程来抑制肺癌细胞的转移和侵袭。     

MiR-338-3p inhibits epithelial-mesenchymal transition in gastric cancer cells by targeting ZEB2 and MACC1/Met/Akt signaling

MicroRNAs (miRNAs) are involved in the epithelial-mesenchymal transition (EMT) process and are associated with metastasis in gastric cancer (GC). MiR-338-3p has been reported to be aberrantly expressed in GC. In the present study, we show that miR-338-3p inhibited the migration and invasion of GC cells in vitro. Knocking down miR-338-3p in GC cells led to mesenchymal-like changes. MiR-338-3p influenced the expression of the EMT-associated proteins by upregulating the epithelial marker E-cadherin and downregulating the mesenchymal markers, N-cadherin, fibronectin, and vimentin. In terms of mechanism, miR-338-3p directly targeted zinc finger E-box-binding protein 2 (ZEB2) and metastasis-associated in colon cancer-1 (MACC1). MiR-338-3p repressed the Met/Akt pathway after MACC1 inhibition. Reintroduction of ZEB2 and MACC1 reversed miR-338-3p-induced EMT suppression. Consistently, inverse correlations were also observed between the expression of miR-338-3p and ZEB2 or MACC1 in human GC tissue samples. In conclusion, miR-338-3p inhibited the EMT progression in GC cells by targeting ZEB2 and MACC1/Met/Akt signaling.     

LncRNA MALAT1 通过调控miR-124-3p/IGF2BP1 分子轴促进宫颈癌细胞增殖和转移

[摘要] 目的：探讨lncRNA MALAT1 通过调控miR-124-3p/IGF2BP1 分子轴介导宫颈癌细胞增殖和转移的影响。方法：选取2014 年4 月至2017 年12 月在贵阳市妇幼保健院妇产科收治的、经手术切除的45 例宫颈癌患者癌组织及相应癌旁组织标本,以及宫颈癌细胞系SiHa、Caski、HeLa 和C33a,采用qPCR法检测癌组织和癌细胞系中MALAT1 的表达水平。构建MALAT1 敲降载体、miR-124-3p inhibitor 及IGF2BP1 过表达载体转染宫颈癌细胞,采用CCK-8、Transwell、Wb及免疫荧光实验探讨MALAT1 或其敲降后通过miR-124-3p/IGF2BP1 分子轴对宫颈癌细胞增殖、侵袭和上皮间质转化的影响。采用双荧光素酶报告基因检测lncRNA MALAT1、miR-124-3p 及IGF2BP1 的靶向调控关系。结果：MALAT1 在宫颈癌组织和细胞系中高表达（P<0.05 或P<0.01）。同时,敲降MALAT1 显著抑制宫颈癌细胞增殖、侵袭和上皮间质转化（P<0.05 或P<0.01）。双荧光素酶报告基因证实MALAT1 靶向作用miR-124-3p 并下调其表达水平,miR-124-3p 可负调控IGF2BP1 的表达。实验进一步证实敲降MALAT1 通过靶向上调miR-124-3p 对IGF2BP1 的抑制作用,进而抑制宫颈癌细胞增殖、侵袭和上皮间质转化（P<0.05 或P<0.01）。结论：lncRNA MALAT1 通过下调miR-124-3p/IGF2BP1 分子轴促进宫颈癌细胞增殖、侵袭和上皮间质转化,为临床宫颈癌早期诊断/治疗提供了潜在的分子靶点。     

Mesenchymal stem cells play a potential role in regulating the establishment and maintenance of epithelial-mesenchymal transition in MCF7 human breast cancer cells by paracrine and induced autocrine TGF-β

Although the epithelial-mesenchymal transition (EMT) is a normal process that occurs during development, it is thought to be associated with cancer progression and metastasis. Emerging evidence links mesenchymal stem cells (MSCs) in the tumor microenvironment with the occurrence of EMT in cancer progression. In this study, the human breast cancer cell line MCF7 was co-cultured with human adipose-derived MSCs (hAD-MSCs) in a transwell system. Co-cultured cells were analyzed for changes in cellular morphology, EMT markers, protein expression and tumor characteristics. We found that co-cultured MCF7 cells underwent EMT and established a stable mesenchymal phenotype after prolonged co-culturing. Here, we demonstrate that paracrine transforming growth factor-β1 (TGF-β1) secreted by hAD-MSCs regulated the establishment of EMT in MCF7 cells by targeting the ZEB/miR-200 regulatory loop. The downregulation of paracrine TGF-β1 levels can inhibit and reverse the EMT progress by downregulating ZEB1/2 and upregulating miR-200b and miR-200c. The maintenance of a stable mesenchymal state by MCF7 cells required the establishment of autocrine TGF-β signaling to drive and sustain ZEB expression, which had been initiated by the prolonged co-culturing with hAD-MSCs. These results suggest that MSCs may promote breast cancer metastasis by stimulating and facilitating the EMT process.     

Intratumoral bidirectional transitions between epithelial and mesenchymal cells in triple‐negative breast cancer

Epithelial–mesenchymal transition (EMT) and its reverse process, mesenchymal–epithelial transition MET, are crucial in several stages of cancer metastasis. Epithelial–mesenchymal transition allows cancer cells to move to proximal blood vessels for intravasation. However, because EMT and MET processes are dynamic, mesenchymal cancer cells are likely to undergo MET transiently and subsequently re‐undergo EMT to restart the metastatic process. Therefore, spatiotemporally coordinated mutual regulation between EMT and MET could occur during metastasis. To elucidate such regulation, we chose HCC38, a human triple‐negative breast cancer cell line, because HCC38 is composed of epithelial and mesenchymal populations at a fixed ratio even though mesenchymal cells proliferate significantly more slowly than epithelial cells. We purified epithelial and mesenchymal cells from Venus‐labeled and unlabeled HCC38 cells and mixed them at various ratios to follow EMT and MET. Using this system, we found that the efficiency of EMT is approximately an order of magnitude higher than that of MET and that the two populations significantly enhance the transition of cells from the other population to their own. In addition, knockdown of Zinc finger E‐box‐binding homeobox 1 (ZEB1) or Zinc finger protein SNAI2 (SLUG) significantly suppressed EMT but promoted partial MET, indicating that ZEB1 and SLUG are crucial to EMT and MET. We also show that primary breast cancer cells underwent EMT that correlated with changes in expression profiles of genes determining EMT status and breast cancer subtype. These changes were very similar to those observed in EMT in HCC38 cells. Consequently, we propose HCC38 as a suitable model to analyze EMT–MET dynamics that could affect the development of triple‐negative breast cancer.     

53BP1 suppresses epithelial–mesenchymal transition by downregulating ZEB1 through microRNA‐200b/429 in breast cancer

Epithelial–mesenchymal transition (EMT) is an important mechanism of cancer invasion and metastasis. Although p53 binding protein 1 (53BP1) has been implicated in several biological processes, its function in EMT of human cancers has not yet been reported. Here, we show that 53BP1 negatively regulated EMT by modulating ZEB1 through targeting microRNA (miR)‐200b and miR‐429. Furthermore, 53BP1 promoted ZEB1‐mediated upregulation of E‐cadherin and also inhibited the expressions of mesenchymal markers, leading to increased migration and invasion in MDA‐MB‐231 breast cancer cells. Consistently, in MCF‐7 breast cancer cells, low 53BP1 expression reduced E‐cadherin expression, resulting in increased migration and invasion. These effects were reversed by miR‐200b and miR‐429 inhibition or overexpression. Sections of tumor xenograft model showed increased ZEB1 expression and decreased E‐cadherin expression with the downregulation of 53BP1. In 18 clinical tissue samples, expression of 53BP1 was positively correlated with miR‐200b and mir‐429 and negatively correlated with ZEB1. It was also found that 53BP1 was associated with lymph node metastasis. Taken together, these results suggest that 53BP1 functioned as a tumor suppressor gene by its novel negative control of EMT through regulating the expression of miR‐200b/429 and their target gene ZEB1.