Transforming growth factor-β1-induced epithelial–mesenchymal transition generates ALDH-positive cells with stem cell properties in cholangiocarcinoma

Epithelial–mesenchymal transition (EMT) is a major factor that facilitates the invasiveness and metastasis of cancer. Recent studies have demonstrated that EMT plays a key role in generating cancer stem cells (CSCs). This study aimed to investigate the effect of EMT on CSCs that were identified as positive for aldehyde dehydrogenase (ALDH) in cholangiocarcinoma (CCA). We demonstrated that transforming growth factor-β1 (TGF-β1)-induced EMT in the human cholangiocarcinoma (CCA) cell line, TFK-1, resulted in the acquisition of mesenchymal traits, as well as the expression of ALDH, which was accompanied by decreased sensitivity to the chemotherapeutic agent, 5-fluorouracil. ALDH-positive cells isolated from TFK-1 cells had higher proliferation potential in vitro and tumourigenic ability in vivo. They also expressed mesenchymal markers. Moreover, the expression levels of TGF-β1 and ALDH1 were correlated with poor prognosis in patients. We conclude that ALDH acts as a marker for CSCs in CCA, and TGF-β1-induced EMT is involved in the generation of CSCs. These findings offer a new tool for the study of CCA stem cells and illustrate a direct link between EMT and the gain of stem-cell properties.     

Eribulin mesilate suppresses experimental metastasis of breast cancer cells by reversing phenotype from epithelial–mesenchymal transition (EMT) to mesenchymal–epithelial transition (MET) states

Background:

Eribulin mesilate (eribulin), a non-taxane microtubule dynamics inhibitor, has shown trends towards greater overall survival (OS) compared with progression-free survival in late-stage metastatic breast cancer patients in the clinic. This finding suggests that eribulin may have additional, previously unrecognised antitumour mechanisms beyond its established antimitotic activity. To investigate this possibility, eribulin''s effects on the balance between epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition (MET) in human breast cancer cells were investigated.

Methods:

Triple negative breast cancer (TNBC) cells, which are oestrogen receptor (ER−)/progesterone receptor (PR−)/human epithelial growth receptor 2 (HER2−) and have a mesenchymal phenotype, were treated with eribulin for 7 days, followed by measurement of EMT-related gene and protein expression changes in the surviving cells by quantitative real-time PCR (qPCR) and immunoblot, respectively. In addition, proliferation, migration, and invasion assays were also conducted in eribulin-treated cells. To investigate the effects of eribulin on TGF-β/Smad signalling, the phosphorylation status of Smad proteins was analysed. In vivo, the EMT/MET status of TNBC xenografts in mice treated with eribulin was examined by qPCR, immunoblot, and immunohistochemical analysis. Finally, an experimental lung metastasis model was utilised to gauge the metastatic activity of eribulin-treated TNBC in the in vivo setting.

Results:

Treatment of TNBC cells with eribulin in vitro led to morphological changes consistent with transition from a mesenchymal to an epithelial phenotype. Expression analyses of EMT markers showed that eribulin treatment led to decreased expression of several mesenchymal marker genes, together with increased expression of several epithelial markers. In the TGF-β induced EMT model, eribulin treatment reversed EMT, coincident with inhibition of Smad2 and Smad3 phosphorylation. Consistent with these changes, TNBC cells treated with eribulin for 7 days showed decreased capacity for in vitro migration and invasiveness. In in vivo xenograft models, eribulin treatment reversed EMT and induced MET as assessed by qPCR, immunoblot, and immunohistochemical analyses of epithelial and mesenchymal marker proteins. Finally, surviving TNBC cells pretreated in vitro with eribulin for 7 days led to decreased numbers of lung metastasis when assessed in an in vivo experimental metastasis model.

Conclusions:

Eribulin exerted significant effects on EMT/MET-related pathway components in human breast cancer cells in vitro and in vivo, consistent with a phenotypic switch from mesenchymal to epithelial states, and corresponding to observed decreases in migration and invasiveness in vitro as well as experimental metastasis in vivo. These preclinical findings may provide a plausible scientific basis for clinical observations of prolonged OS by suppression of further spread of metastasis in breast cancer patients treated with eribulin.     

The rejuvenated scenario of epithelial–mesenchymal transition (EMT) and cancer metastasis

The molecular mechanisms underlying cancer progression and metastasis are still poorly understood. In recent years, the epithelial-to-mesenchymal transition (EMT), a traditional phenomenon revealed in embryonic development, has been gradually accepted as a potential mechanism underlying cancer progression and metastasis. Many cell signaling pathways involved in development have been shown to contribute to EMT. An increasing number of genetic and epigenetic elements have been discovered, and their cross-talk relationship in EMT remains to be explored. In addition, accumulating experimental evidence suggests that EMT plays a critical role in different aspects of cancer progression, such as metastasis, stem cell traits, and chemoresistance. However, there are some disagreements and debate about these studies, which raise critical questions worthy of further investigation. Solving these questions will lead to a more complete understanding of cancer metastasis. Due to the close relationship of EMT to cancer metastasis and chemoresistance, targeting EMT or reversing EMT is likely to lead to novel therapeutic approaches for the treatment of human cancers.     

The relationship between Bmi-1 and the epithelial–mesenchymal transition in lung squamous cell carcinoma

This study aimed to investigate the expression of Bmi-1 in lung squamous cell carcinoma tissues and the relationship between Bmi-1 and the epithelial-mesenchymal transition. RT-PCR and western blot analysis were performed to detect the expression of Bmi-1, E-cadherin, and Vimentin in 56 cases of lung squamous cell carcinoma tissues and adjacent normal tissues. The positive rates of Bmi-1, E-cadherin, and Vimentin mRNA expression in lung squamous cell carcinoma tissues were 73.2, 42.9, and 58.9%, respectively; compared to the expression of these genes in adjacent normal tissues (14.3, 75.0, and 28.6%), the differences were significant (P < 0.05). The expression of Bmi-1 in lung squamous cell carcinoma tissues showed a negative correlation with that of E-cadherin (r = -0.372, P = 0.005) and a positive correlation with that of Vimentin (r = 0.315, P = 0.02). The expression of Bmi-1 and Vimentin mRNA and protein in lung squamous cell carcinoma tissues was significantly higher than that in adjacent normal tissues (P < 0.05), and the expression of Bmi-1 and Vimentin in patients with lymph node and distal metastasis was significantly higher than that in patients without lymph node and distal metastasis (P < 0.05). The expression of E-cadherin mRNA and protein in lung squamous cell carcinoma tissues was significantly lower than that in adjacent normal tissues (P < 0.05), and the expression in patients with lymph node and distal metastasis was significantly lower than that in patients without lymph node and distal metastasis (P < 0.05). The expression of Bmi-1, E-cadherin, and Vimentin was not associated with the patient's sex, age, tumor size or degree of tumor differentiation (P > 0.05). The increase in Bmi-1 expression was accompanied by the down-regulation of E-cadherin expression and up-regulation of Vimentin expression. Bmi-1 may be associated with the epithelial-mesenchymal transition in lung squamous cell carcinoma and the occurrence, invasion, and metastasis of lung squamous cell carcinoma.     

Prognostic impact of histological categorisation of epithelial–mesenchymal transition in colorectal cancer

Background:

The crosstalk between cancer cells and stroma is involved in the acquired capability for metastasis through the induction of epithelial–mesenchymal transition (EMT). We aimed to clarify the prognostic value of the histological category of EMT in colorectal cancer (CRC).

Methods:

Tumour EMT was graded into one of three histological categories on the basis of integrated assessment of poorly differentiated clusters and pro-EMT desmoplasia at the leading edge of the primary tumour (Histology^EMT). Stage II and III CRC patients (cohort 1, N=500) and stage IV patients (cohort 2, N=196) were retrospectively analysed.

Results:

In cohort 1, patients were stratified into three groups with widely different disease-free survival rates (95%, 83% and 39%) on the basis of Histology^EMT (P<0.0001). In cohort 2, Histology^EMT significantly stratified overall survival of patients irrespective of metasectomy. Multivariate analyses indicated that Histology^EMT had a strong prognostic impact independent of staging factors. Statistically, Histology^EMT had a better prognostic stratification power than T and N stages; however, in cohort 2, the power of M substage was superior.

Conclusions:

A histological model to categorise EMT by integrated assessment of dedifferentiation and desmoplastic environment is a potent prognostic index independent of staging factors.     

Snail regulates Nanog status during the epithelial–mesenchymal transition via the Smad1/Akt/GSK3β signaling pathway in non-small-cell lung cancer

The epithelial–mesenchymal transition (EMT), a crucial step in cancer metastasis, is important in transformed cancer cells with stem cell-like properties. In this study, we established a Snail-overexpressing cell model for non-small-cell lung cancer (NSCLC) and investigated its underlying mechanism. We also identified the downstream molecular signaling pathway that contributes to the role of Snail in regulating Nanog expression. Our data shows that high levels of Snail expression correlate with metastasis and high levels of Nanog expression in NSCLC. NSCLC cells expressing Snail are characterized by active EMT characteristics and exhibit an increased ability to migrate, chemoresistance, sphere formation, and stem cell-like properties. We also investigated the signals required for Snail-mediated Nanog expression. Our data demonstrate that {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, SB431542, LDN193189, and Noggin pretreatment inhibit Snail-induced Nanog expression during EMT. This study shows a significant correlation between Snail expression and phosphorylation of Smad1, Akt, and GSK3β. In addition, pretreatment with SB431542, LDN193189, or Noggin prevented Snail-induced Smad1 and Akt hyperactivation and reactivated GSK3β. Moreover, {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 pretreatment prevented Akt hyperactivation and reactivated GSK3β without altering Smad1 activation. These findings provide a novel mechanistic insight into the important role of Snail in NSCLC during EMT and indicate potentially useful therapeutic targets for NSCLC.     

Molecules involved in epithelial–mesenchymal transition and epithelial–stromal interaction in phyllodes tumors: implications for histologic grade and prognosis

The aim of this study was to investigate the expression of molecules associated with epithelial–mesenchymal transition (EMT) and epithelial–stromal interactions (ESI) and to evaluate their roles in phyllodes tumors (PTs). Tissue microarrays (TMAs) were constructed from 207 PT specimens (157 benign, 34 borderline and 16 malignant). The presence of EMT-related markers including N-cadherin, Twist, TGF-beta, HMGA2, S100A4 and Ezrin as well as ESI-related molecules such as SDF1 and CXCR4 among the TMAs was assessed immunohistochemically. Immunohistochemical results were analyzed in terms of clinicopathologic parameters. For higher grade PTs, expressions of Twist (p < 0.001), HMGA2 (p = 0.005), S100A4 (p < 0.001), CXCR4 (p < 0.001) and TGF-beta (p < 0.001) were higher. As PTs showed higher stromal cellularity, higher stromal mitosis, stromal overgrowth and infiltrative tumor margin, the expressions of Twist, HMGA2 and CXCR4 in the stromal component thereof were increased (p < 0.05). High Twist expression in the stromal component was associated with shorter disease-free survival (DFS) and overall survival (OS) (p < 0.001) as well as shorter OS in multivariate COX analysis (p = 0.031, odds ratio: 24.6). In conclusion, the expressions of Twist, HMGA2, TGF-beta and S100A4, which are EMT-associated molecules, and CXCR4, an ESI-associated molecule, were increased in the stromal component of advanced grade PTs. Further, high expression of Twist in the stromal component was correlated with poorer prognoses.     

Prognostic significance of epithelial–mesenchymal transition proteins Twist and Foxc2 in phyllodes tumours of the breast

Epithelial–mesenchymal transition (EMT), an important process during embryonic development, is reportedly exploited during tumour progression. Deregulation of EMT-related molecules has been shown in many malignancies, including breast carcinoma. We aim to investigate the clinical relevance and prognostic significance of EMT proteins, Twist and Foxc2, in breast phyllodes tumours (PTs). The study cohort comprised 271 PTs diagnosed from 2003 to 2010. Of these, 188 (69.4 %) were benign, 60 (22.1 %) borderline, and 23 (8.5 %) malignant. Immunohistochemistry for Twist and Foxc2 was performed on tissue microarray sections. Percentage of tumour cells stained was evaluated and correlated with clinicopathological parameters and clinical outcome. Twist and Foxc2 stromal nuclear expression was associated with tumour grade (P = 0.038 and 0.012). Foxc2 stromal nuclear expression was positively correlated with epithelial expression (P < 0.001), tumour relapse, and metastasis (P = 0.037). Furthermore, stromal nuclear immunoreactivity of Twist and Foxc2 was interrelated (P < 0.001). Tumours expressing Foxc2 and those co-expressing both Twist and Foxc2 revealed a shorter time to recurrence (P < 0.001 and 0.001) and death (P = 0.044 and 0.015). Twist and Foxc2 stromal expression in PTs was significantly correlated with tumour grade and worse histological features. In addition, expression of Foxc2 and co-expression of Twist and Foxc2 in the stroma of PTs contributed to poorer prognosis. Clinical relevance of EMT-related molecules may be worthy of further investigation in PTs.     

Notch1 signaling regulates the epithelial–mesenchymal transition and invasion of breast cancer in a Slug-dependent manner

Background

The epithelial–mesenchymal transition (EMT) is crucial for the invasion and metastasis of breast cancer. However, how Notch signaling regulates the EMT process and invasion in breast cancer remains largely unknown.

Methods

The impact of Notch1 silencing by specific shRNAs on the EMT and invasion of human breast cancer MCF-7 and MDA-MB-231 cells as well as xenografts was tested by western blot, real-time polymerase chain reaction (RT-PCR), immunofluorescence, transwell, and immunohistochemistry assays. The effect of Slug silencing or upregulation on the EMT and invasion of breast cancer cells was analyzed, and the effect of Notch1 signaling on Slug expression was determined by the luciferase reporter assay.

Results

The Notch1 intracellular domain (N1ICD) and Jagged1 were expressed in breast cancer cells. Notch1 silencing reversed the spontaneous EMT process and inhibited the migration and invasion of breast cancer cells and the growth of xenograft breast cancers. The expression of N1ICD was upregulated significantly by Jagged1-mediated Notch signaling activation. Moreover, Jagged1-mediated Notch signaling promoted the EMT process, migration, and invasion of breast cancer cells, which were abrogated by Notch silencing. Furthermore, the N1ICD positively regulated the Slug expression by inducing Slug promoter activation. Importantly, the knockdown of Slug weakened the invasion ability of breast cancer cells and reversed the Jagged1-induced EMT process with significantly decreased expression of vimentin and increased expression of E-cadherin. In addition, Slug overexpression restored the Notch1 knockdown-suppressed EMT process.

Conclusions

Our novel data indicate that Notch signaling positively regulates the EMT, invasion, and growth of breast cancer cells by inducing Slug expression. The Notch1–Slug signaling axis may represent a potential therapeutic target for breast cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0295-3) contains supplementary material, which is available to authorized users.