Project description:Immortalized non-cancerous human mammary epithelial cells (HMLE) were transfected to express the murine fusion protein Twist1-estrogen receptor(point mutation G525R) (HTER). Twist1-mediated gene expression is activated by stimulation with 4-hydroxytamoxifen for several days and induces an epithelial-mesenchymal transition (EMT) in HTER cells. In breast cancer, EMT equips cancer cells for metastasis and therapy resistance. As control, HTER cells were treated with vehicle (methanol). As additional controls, HMLE cells were stimulated with 4-hydroxytamoxifen or methanol, respectively. Prior to RNA sequencing, EMT-undergoing HTER cells were sorted by fluorescence-activated cell sorting (FACS) based on E-Cadherin and CD44 surface protein levels into three populations, epithelial (E), hybrid epithelial-mesenchymal (EM), and mesenchymal (M): E-Cadherin_high_CD44_low (E), E-Cadherin_medium_CD44_medium (EM), and E-Cadherin_low_CD44_high (M).
Project description:Glioblastoma multiforme (GBM) is the most common and aggressive malignant brain tumor among adults, which is characterized by high invasion, migration and proliferation abilities. One important process that contributes to the invasiveness of GBM is the epithelial to mesenchymal transition (EMT). EMT is regulated by a set of defined transcription factors which tightly regulate this process, among them is the basic helix-loop-helix family member, TWIST1. Here we show that TWIST1 is methylated on lysine-33 at chromatin by SETD6, a methyltransferase with expression levels correlating with poor survival in GBM patients. RNA-seq analysis in U251 GBM cells suggested that both SETD6 and TWIST1 regulate cell adhesion and migration processes. We further show that TWIST1 methylation attenuates the expression of the long-non-coding RNA, LINC-PINT, thereby suppressing EMT in GBM. Mechanistically, TWIST1 methylation represses the transcription of LINC-PINT by increasing the occupancy of EZH2 and the catalysis of the repressive H3K27me3 mark at the LINC-PINT locus. Under un-methylated conditions, TWIST1 dissociates from the LINC-PINT locus, allowing the expression of LINC-PINT which leads to increased cell adhesion and decreased cell migration. Together, our findings unravel a new mechanistic dimension for selective expression of LINC-PINT mediated by TWIST1 methylation.
Project description:Elevated lipocalin-2 (Lcn2) has been observed in multiple human cancers, but its biological roles remain unclear. Our purpose in this study was to investigate whether Lcn2 is involved in hepatocellular carcinoma (HCC) development via its involvement in invasion and metastasis. Using unsupervised hierarchical clustering analysis of tissue samples, we identified preferential expression of Lcn2 (>2-fold change) in the tumor group (differentiated group) versus the non-tumor group (liver cirrhosis group). LCN2 immunoreactivity was positively correlated with TNM stage (r = 0.194, P = 0.020), but not with differentiation or recurrence of HCC. Over-expression of Lcn2 was observed in HLK-2, HKK-2, and HLK-5 HCC cells. Knock-down of Lcn2 by shRNA in HKK-2 cells was correlated with the down-regulation of E-cadherin, CK-8, CK-18, and desmoplakin I/II (DesI/II) and the up-regulation of N-cadherin, vimentin (VIM), and fibronectin (FN), which are markers of the epithelial-mesenchymal transition (EMT) associated with tumor progression. The characteristics of EMT were reversed by adenoviral transduction of Lcn2 into SH-J1 cells. EGF or TGF-β treatment resulted in downregulation of Lcn2 with a concomitant change in EMT. Stable Lcn2 expression in HCC cells reduced the expression of the transcription factor Twist1, resulting in the inhibition of cell proliferation, migration, and invasion in vitro, and suppressed tumor growth and metastatic ability in a mouse model. These findings suggest that Lcn2 can reverse the EMT in HCC through transcriptional suppression of Twist 1. Thus, Lcn2 is a candidate metastasis suppressor and a potential therapeutic target for HCC. Unsupervised hierarchical clustering separated the samples into two main groups: a non-tumor group (NT, n = 40) and a HCC group (HCC, n = 40), and into two subgroups: a liver cirrhosis group (LC, n = 20) and a differentiated HCC group (difHCC, n = 20). Lcn2 was one of the unique genes with a two-fold or greater difference in expression from the mean with P < 0.01 based on the t-test for hierarchical clustering analysis.
Project description:Cell plasticity is emerging as a key regulator of tumor progression and metastasis. During carcinoma dissemination epithelial cells undergo epithelial to mesenchymal transition (EMT) processes characterized by the acquisition of migratory/invasive properties, while the reverse, mesenchymal to epithelial transition (MET) process, is also essential for metastasis outgrowth. Different transcription factors, called EMT-TFs, including Snail, bHLH and Zeb families are drivers of the EMT branch of epithelial plasticity, and can be post-transcriptionally downregulated by several miRNAs, as the miR-200 family. The specific or redundant role of different EMT-TFs and their functional interrelations are not fully understood. To study the interplay between different EMT-TFs, comprehensive gain and loss-of-function studies of Snail1, Snail2 and/or Zeb1 factors were performed in the prototypical MDCK cell model system. We here describe that Snail1 and Zeb1 are mutually required for EMT induction while continuous Snail1 and Snail2 expression, but not Zeb1, is needed for maintenance of the mesenchymal phenotype in MDCK cells. In this model system, EMT is coordinated by Snail1 and Zeb1 through transcriptional and epigenetic downregulation of the miR-200 family. Interestingly, Snail1 is involved in epigenetic CpG DNA methylation of the miR-200 loci, essential to maintain the mesenchymal phenotype. The present results thus define a novel functional interplay between Snail and Zeb EMT-TFs in miR200f regulation providing a molecular link to their previous involvement in the generation of EMT process in vivo. Expression analysis of MDCK over-expression EMT-TF Analysis of 7 overexpression MDCK cells each of them using biological rpelicates (MDCK-E47, Snail2, Snail1, Twist1, Tiwst2, Zeb1, Zeb2)
Project description:During Epithelial-Mesenchymal Transition (EMT), apical-basal polarized epithelial cells are converted to front-to-back polarized mesenchymal cells that only form loose cell-cell adhesions. These phenotypic changes are accompanied by acquisition of increased motility and invasiveness. EMT programs are orchestrated by pleiotropic transcription factors (TFs), such as Twist1 and Snail1 and effect morphogenetic steps during embryogenesis, including mesoderm formation and neural crest migration. EMTs have also been implicated in the acquisition of aggressive traits by carcinoma cells, including the ability to complete several steps of the metastatic cascade as well as propagation of the tumor by single cells (clonogenicity), a defining trait of tumor-initiating or cancer stem cells. However, the molecular links between the expression of EMT-TFs, the process of EMT and acquisition of clonogenicity remain obscure. Using inducible Twist1 or Snail1 expressed in CD24-positive mammary epithelial cells, we show that clonal growth in anchorage independence and EMT are induced sequentially and independently: clonogenic potential is induced prior to EMT and requires transient TF-activity. By contrast, EMT depends on continuous TF-activation over a longer period. In 3D-collagen assays, continuous Twist1 activity suppresses colony formation, whereas transient activation induces highly invasive growth independently of EMT. In conclusion, our results demonstrate that transient Twist1 activation suffices to drive tumor progression of CD24-positive breast epithelial cells, assessed by invasive as well as anchorage-independent clonal growth, whereas chronic Twist1 exposure can suppress these traits of aggressive tumor cells. We performed gene expression microarray analysis on CD24high and CD24negative populations derived from HMLE-Twist1-ER or HMLE-Snail1-ER cell lines upon various culture conditions
Project description:Using a TWIST1-inducible epithelial-to-mesenchymal transition (EMT) model in HMLE cells, miRNA changes were profiled at different time points during an active EMT.