Induction of an EMT-like transformation and MET in vitro

Mnt Represses Epithelial Identity To Promote Epithelial-to-Mesenchymal Transition

The multistep process of epithelial-to-mesenchymal transition (EMT), whereby static epithelial cells become migratory mesenchymal cells, plays a critical role during various developmental contexts, wound healing, and pathological conditions such as cancer metastasis. Despite the established function of basic helix-loop-helix (bHLH) transcription factors (TFs) in cell fate determination, only a few have been examined for their role in EMT. Here, using transcriptome analysis of distinct stages during stepwise progression of transforming growth factor beta (TGFβ)-induced EMT in mammary epithelial cells, we revealed distinct categories of bHLH TFs that show differential expression kinetics during EMT. Using a short interfering RNA-mediated functional screen for bHLH TFs during EMT, we found Max network transcription repressor (MNT) to be essential for EMT in mammary epithelial cells. We show that the depletion of MNT blocks TGFβ-induced morphological changes during EMT, and this is accompanied by derepression of a large number of epithelial genes. We show that MNT mediates the repression of epithelial identity genes during EMT by recruiting HDAC1 and mediating the loss of H3K27ac and chromatin accessibility. Lastly, we show that MNT is expressed at higher levels in EMT-High breast cancer cells and is required for their migration. Taken together, these findings establish MNT as a critical regulator of cell fate changes during mammary EMT. IMPORTANCE The bHLH TF Mnt promotes epithelial to mesenchymal transition through epigenetic repression of the epithelial gene expression program.

Simulation of multiple microenvironments shows a pivot role of RPTPs on the control of Epithelial-to-Mesenchymal Transition

Epithelial-to-Mesenchymal Transition (EMT) is a natural and reversible process involved in embryogenesis, wound healing and thought to participate in the process of metastasis. Multiple signals from the microenvironment have been reported to drive EMT. However, the tight control of this process on physiological scenarios and how it is disrupted during cancer progression is not fully understood. Here, we analysed a regulatory network of EMT accounting for 10 key microenvironment signals focusing on the impact of two cell contact signals on the reversibility of EMT and the stability of resulting phenotypes. The analysis showed that the microenvironment is not enough for stabilizing Hybrid and Amoeboid-like phenotypes, requiring intracellular de-regulations as reported during cancer progression. Our simulations demonstrated that RPTP activation by cell contacts have the potential to inhibit the process of EMT and trigger its reversibility under tissue growth and chronic inflammation scenarios. Simulations also showed that hypoxia inhibits the capacity of RPTPs to control EMT. Our analysis further provided a theoretical explanation for the observed correlation between hypoxia and metastasis under chronic inflammation, and predicted that de-regulations in FAT4 signalling may promote Hybrid stabilization. Taken together, we propose a natural control mechanism of EMT that supports the idea that EMT is tightly regulated by the microenvironment.

Toward Modeling Context-Specific EMT Regulatory Networks Using Temporal Single Cell RNA-Seq Data

Epithelial-mesenchymal transition (EMT) is well established as playing a crucial role in cancer progression and being a potential therapeutic target. To elucidate the gene regulation that drives the decision making of EMT, many previous studies have been conducted to model EMT gene regulatory circuits (GRCs) using interactions from the literature. While this approach can depict the generic regulatory interactions, it falls short of capturing context-specific features. Here, we explore the effectiveness of a combined bioinformatics and mathematical modeling approach to construct context-specific EMT GRCs directly from transcriptomics data. Using time-series single cell RNA-sequencing data from four different cancer cell lines treated with three EMT-inducing signals, we identify context-specific activity dynamics of common EMT transcription factors. In particular, we observe distinct paths during the forward and backward transitions, as is evident from the dynamics of major regulators such as NF-KB (e.g., NFKB2 and RELB) and AP-1 (e.g., FOSL1 and JUNB). For each experimental condition, we systematically sample a large set of network models and identify the optimal GRC capturing context-specific EMT states using a mathematical modeling method named Random Circuit Perturbation (RACIPE). The results demonstrate that the approach can build high quality GRCs in certain cases, but not others and, meanwhile, elucidate the role of common bioinformatics parameters and properties of network structures in determining the quality of GRCs. We expect the integration of top-down bioinformatics and bottom-up systems biology modeling to be a powerful and generally applicable approach to elucidate gene regulatory mechanisms of cellular state transitions.

Measuring systematic changes in invasive cancer cell shape using Zernike moments

We study the shape characteristics of osteosarcoma cancer cell lines on surfaces of differing hydrophobicity using Zernike moments to represent cell shape. We compare the shape characteristics of four invasive cell lines with a corresponding less-invasive parental line on three substrates. Cell shapes of each pair of cell lines are quite close and display overlapping characteristics. To quantitatively study shape changes in high-dimensional parameter space we project down to principal component space and define a vector that summarizes average shape differences. Using this vector we find that three of the four pairs of cell lines show similar changes in shape, while the fourth pair shows a very different pattern of changes. We find that shape differences are sufficient to enable a neural network to classify cells accurately as belonging to the highly invasive or the less invasive phenotype. The patterns of shape changes were also reproducible for repetitions of the experiment. We also find that shape changes on different substrates show similarities between the eight cells studied, but the differences were typically not enough to permit classification. Our paper strongly suggests that shape may provide a means to read out the phenotypic state of some cell types, and shape analysis can be usefully performed using a Zernike moment representation.

CCL25/CCR9 Signal Promotes Migration and Invasion in Hepatocellular and Breast Cancer Cell Lines

Cancer is one of the most lethal diseases worldwide, and metastasis is the most common cause of patients' deaths. Identification and inhibition of markers involved in metastasis process in cancer cells are promising works to block metastasis and improve prognoses of patients. Chemokines are a superfamily of small, chemotactic cytokines, whose functions are based on interaction with corresponding receptors. It has been found that one of the functions of chemokines is to regulate migration and invasion abilities of lymphocytes, as well as cancer cells. Chemokine receptor 9 (CCR9) regulates trafficking of lymphocytes and cancer cell lines when interacting with its exclusive ligand chemokine 25 (CCL25). However, the mechanisms of CCL25/CCR9 signal that regulates metastasis of cancer cells are not completely known yet. In this study, we stimulated or inhibited CCL25/CCR9 signal in breast cancer cell line (MDA-MB-231) and hepatocellular cancer cell lines (HepG2 and HUH7), and found that CCL25/CCR9 signal resulted in different promotion of migration and invasion in different cell lines. These phenomena could be explained by selective regulation of several markers of epithelial-mesenchymal transition (EMT). Our findings suggested that CCL25/CCR9 signal may provide cancer cells with chemotactic abilities through influencing several EMT markers.

Wnt3a expression is associated with epithelial-mesenchymal transition and promotes colon cancer progression

Introduction

Epithelial–mesenchymal transition (EMT) contributes to the progression and metastasis of cancer cells and is associated with a more invasive phenotype of cancer. The Wnt/β-catenin signaling pathway is one of the major pathways involved in EMT regulation. Many studies provide evidence that β-catenin, the key regulator of the canonical Wnt signaling pathway, is important in regulating EMT in cancer. However, the roles of Wnt3a, the representative canonical Wnt ligand, in EMT and colon cancer progression have not yet been fully explored.

Methods

The expression levels of Wnt3a and EMT-associated proteins (E-cadherin, vimentin, and β-catenin) were assessed by immunohistochemistry in human colon cancer tissues to evaluate the clinicopathological significance of Wnt3a, as well as the correlation between Wnt3a and EMT. We then upregulated Wnt3a expression in HCT116 colon cancer cells, established a nude mouse xenograft model, detected the expression of EMT and Wnt/β-catenin signaling-associated proteins, and observed invasion and clone-initiating abilities.

Results

In 203 human colon cancer tissue samples, Wnt3a protein overexpression was related to colon cancer histological differentiation (P = 0.004), clinical stage (P = 0.008), presence of metastasis and recurrence (P = 0.036), and survival time (P = 0.007) of colon cancer patients. Wnt3a expression was notably concomitant with EMT immunohistochemical features, such as reduced expression of the epithelial marker E-cadherin (P = 0.012), increased expression of the mesenchymal marker vimentin (P = 0.002), and cytoplasmic distribution of β-catenin (P = 0.021). Results of in vitro and in vivo experiments showed that Wnt3a overexpression could alter cell morphology, regulate EMT-associated protein expression, and enhance clone-initiation and invasion. Dkk1 (antagonist of Wnt/β-catenin signaling) could also partially reverse the expression of EMT-associated proteins in Wnt3a-overexpressing cells.

Conclusions

Wnt3a expression was associated with EMT and promoted colon cancer progression. The EMT-inducing effect was partially due to the stimulative effect of Wnt3a on the Wnt/β-catenin pathway.

Mutant p53 promotes epithelial-mesenchymal plasticity and enhances metastasis in mammary carcinomas of WAP-T mice

To study the postulated mutant p53 (mutp53) "gain of function" effects in mammary tumor development, progression and metastasis, we crossed SV40 transgenic WAP-T mice with mutant p53 transgenic WAP-mutp53 mice. Compared to tumors in monotransgenic WAP-T mice, tumors in bitransgenic WAP-T x WAP-mutp53 mice showed higher tumor grading, enhanced vascularization, and significantly increased metastasis. Bitransgenic tumors revealed a gene signature associated with the oncogenic epithelial-mesenchymal transition pathway (EMT gene signature). In cultures of WAP-T tumor-derived G-2 cancer cells, which are comprised of subpopulations displaying "mesenchymal" and "epithelial" phenotypes, this EMT gene signature was associated with the "mesenchymal" compartment. Furthermore, ectopic expression of mutp53 in G-2 cells sufficed to induce a strong EMT phenotype. In contrast to these in vitro effects, monotransgenic and bitransgenic tumors were phenotypically similar suggesting that in vivo the tumor cell phenotype might be under control of the tumor microenvironment. In support, orthotopic transplantation of G-2 cells as well as of G-2 cells expressing ectopic mutp53 into syngeneic mice resulted in tumors with a predominantly epithelial phenotype, closely similar to that of endogenous primary tumors. We conclude that induction of an EMT gene signature by mutp53 in bitransgenic tumors primarily promotes tumor cell plasticity, that is, the probability of tumor cells to undergo EMT processes under appropriate stimuli, thereby possibly increasing their potential to disseminate and metastasize.

Prognostic significance of E-cadherin expression in hepatocellular carcinoma: a meta-analysis

Backgrounds

Hepatocellular Carcinoma (HCC) is one of the most common malignancy of liver and HCC-related morbidity and mortality remains at high level. Researchers had investigated whether and how reduced E-cadherin expression impacted the prognosis of patients with HCC but the results reported by different teams remain inconclusive.

Methods

A systematic literature search was performed in all available databases to retrieve eligible studies and identify all relevant data, which could be used to evaluate the correlation between reduced E-cadherin expression and clinicopathological features and prognosis for HCC patients. A fixed or random effects model was used in this meta-analysis to calculate the pooled odds ratios (OR) and weighted mean differences (WMD) with 95% confidence intervals (CI).

Results

Total 2439 patients in thirty studies matched the selection criteria. Aggregation of the data suggested that reduced E-cadherin expression in HCC patients correlated with poor 1-, 3- and 5-year overall survival. The combined ORs were 0.50 (n = 13 studies, 95% CI: 0.37–0.67, Z = 4.49, P<0.00001), 0.39 (n = 13 studies, 95% CI: 0.28–0.56, Z = 5.12, P<0.00001), 0.40 (n = 11 studies, 95% CI: 0.25–0.64, Z = 3.82, P = 0.0001), respectively. Additionally, the pooled analysis denoted that reduced E-cadherin expression negatively impacts recurrence-free survival (RSF) with no significant heterogeneity. The pooled ORs for 1-, 3- and 5- year RSF affected by down-regulated E-cadherin were 0.73 (n = 6 studies, 95% CI: 0.54–1.00, Z = 1.95, P = 0.05), 0.70 (n = 6 studies, 95% CI: 0.52–0.95, Z = 2.32, P = 0.02), 0.66 (n = 5 studies, 95% CI: 0.48–0.90, Z = 2.64, P = 0.008). And what’s more, reduced E-cadherin expression tended to be significantly associated with metastasis (OR = 0.31, 95% CI: 0.16–0.60, Z = 3.50, P = 0.0005), vascular invasion (OR = 0.76, 95% CI: 0.59–0.98, Z = 2.14, P = 0.03), advanced differentiation grade (OR = 0.31, 95% CI: 0.21–0.45, Z = 6.04, P<0.00001) and advanced TMN stage (T3/T4 versus T1/T2) (OR = 0.61,95% CI:0.38–0.98, Z = 2.05, P = 0.04).

Conclusions

Reduced E-cadherin expression indicates a poor prognosis for patients with HCC, and it may have predictive potential for prognosis of HCC patients.

Blocking PI3K/Akt signaling attenuates metastasis of nasopharyngeal carcinoma cells through induction of mesenchymal-epithelial reverting transition

In the present study, we evaluated the role of phosphatidylinositol-3 OH kinase/protein kinase B (PI3K/Akt) signaling on changes to epithelial-to-mesenchymal reverting transition (EMrT) in nasopharyngeal carcinoma (NPC). Protein expression levels of p-Akt (Ser473), and the epithelial‑to-mesenchymal transition (EMT) markers E-cadherin, vimentin, α smooth muscle actin (α-SMA), were examined in clinical samples from 130 cases of undifferentiated non-keratinizing NPC, and 20 cases of benign nasopharyngitis. The relationship between protein expression levels and the statue of NPC lymph node metastasis was analyzed. The poorly‑differentiated NPC cell line CNE2Z was treated with various concentrations of the PI3K inhibitor, LY294002, and western blotting and quantitative polymerase chain reaction assays were used to analyze the activation of PI3K/Akt signaling and expression of E-cadherin, vimentin and α-SMA. The ability of cellular migration and invasion was assessed using Transwell assays. The in vivo effects of LY294002 on metastasis and expression of EMT markers in CNE2Z cells was evaluated using tumor xenograft experiments. The expression levels of p-Akt (Ser473) in NPC samples were higher than those in nasopharyngitis. There were reduced levels of membrane E-cadherin protein expression, and increased cytosol vimentin and α-SMA expression levels in NPC samples compared with those in nasopharyngitis samples. High expression levels of p-Akt (Ser473), vimentin, and α-SMA, and low expression levels of E-cadherin were positively associated with lymph node metastasis of NPC cells. Treating CNE2Z cells with LY294002 inhibited p-Akt (Ser473), vimentin and α-SMA expression but upregulated E-cadherin expression, leading to significantly attenuated cell invasion and migration. Administration of mice with LY294002 resulted in upregulation of membrane E-cadherin, and downregulation of vimentin and α-SMA in CNE2Z xenografts, with reduced pulmonary metastasis. Our findings suggest that inhibiting the PI3K/Akt pathway using LY294002 attenuated NPC metastasis via induction of EMrT.

SILAC labeling coupled to shotgun proteomics analysis of membrane proteins of liver stem/hepatocyte allows to candidate the inhibition of TGF-beta pathway as causal to differentiation

BACKGROUND

Despite extensive research on hepatic cells precursors and their differentiated states, much remains to be learned about the mechanism underlying the self-renewal and differentiation.

RESULTS

We apply the SILAC (stable isotope labeling by amino acids in cell culture) approach to quantitatively compare the membrane proteome of the resident liver stem cells (RLSCs) and their progeny spontaneously differentiated into epithelial/hepatocyte (RLSCdH). By means of nanoLC-MALDI-TOF/TOF approach, we identified and quantified 248 membrane proteins and 57 of them were found modulated during hepatocyte differentiation. Functional clustering of differentially expressed proteins by Ingenuity Pathway Analysis revealed that the most of membrane proteins found to be modulated are involved in cell-to-cell signaling/interaction pathways. Moreover, the upstream prediction analysis of proteins involved in cell-to-cell signaling and interaction unveiled that the activation of the mesenchymal to epithelial transition (MET), by the repression of TGFB1/Slug signaling, may be causal to hepatocyte differentiation.

CONCLUSIONS

Taken together, this study increases the understanding of the underlying mechanisms modulating the complex biological processes of hepatic stem cell proliferation and differentiation.