Epithelial-mesenchymal Transition Of MCF-7 Cells Research Articles

Macrophage induced ERK-TGF-β1 signaling in MCF7 breast cancer cells result in reversible cancer stem cell plasticity and epithelial mesenchymal transition

BackgroundBreast cancer is a heterogenous disease composed of multiple clonal populations and the mechanism by which the tumor microenvironment induces cancer stem cell plasticity is not fully understood. MethodsMCF7 breast cancer cells were treated with macrophage conditioned medium (MɸCM). PD98059 and SB431542 were used for ERK and TGF-βR inhibition respectively. Epithelial-mesenchymal transition (EMT) and cancer stem cell markers (CSC) were studied using qRT-PCR and flowcytometry. SCID mice were used for animal experiments. ResultsMɸCM- induced ERK/TGF-β1 signaling led to enrichment of CSC and EMT in MCF7 cells and mammospheres. These effects were abrogated by both MEK inhibitor PD98059 (TGF-β1 synthesis) and SB431542 (TGF-β1 signaling). The increase in CSC was both hybrid (ALDH1+) and mesenchymal (CD44+ CD24− cells). Increase in hybrid E/M state was at a single cell level as confirmed by the increase in both claudin-1 (E) and vimentin (M). This did not have any growth advantage in SCID mice and monitoring of CSC and EMT markers before and after growth in SCID mice indicated reversal of these markers in tumor cells recovered from mice. Removal of MɸCM and neutralization of TNF-α, IL-6 and IL-1β in MɸCM abrogated ERK phosphorylation, TGF-β and CSC enrichment indicating the requirement of continuous signaling for maintenance. ConclusionsERK signaling plays an important role in MɸCM- induced EMT and CSC plasticity which is completely reversible upon withdrawal of signals. General significanceOur experimental observations support the semi-independent nature of EMT-stemness connection which is very dynamic and reversible depending on the microenvironment.

Evaluation of anti-epithelial-mesenchymal transition property of Garcinia mangostana rind extract

BackgroundEpithelial-mesenchymal transition (EMT) helps solid tumors to lose their intercellular adhesive property and drives metastasis. As mangosteen fruit is known for many beneficial effects including antimicrobial, antioxidant, and anti-tumorigenic properties and has been used widely in traditional medicine, we interrogated its possible anti-metastatic effect on MCF-7 breast cancer cells.ResultsWe found that aqueous mangosteen rind extract (MRE) inhibited growth of MCF-7 and altered the transcript levels of ERα, ERβ, and EGFR genes. Additionally, the MRE changed the expression of important markers of EMT, E-Cadherin, N-Cadherin, Snail, and MMP-9. Moreover, MRE inhibited migration of MCF-7 cells.ConclusionThe results suggest that MRE suppresses growth and inhibits epithelial-mesenchymal transition in MCF-7 cells.

MiR-155 promotes proliferation and epithelial-mesenchymal transition of MCF-7 cells.

Breast cancer (BC) is the second leading cause of cancer-associated deaths among women worldwide. Increasing evidence has indicated that microRNAs (miRNAs) have demonstrated great potential for improving the diagnosis and therapy for BC. In the present study, miRNA-155 was detected in human BC tissues using reverse transcription-quantitative (RT-q)PCR. RT-qPCR and western blot assays were used to analyze the levels of transforming growth factor β receptor type II (TGFBR2) in human BC tissues. MCF-7 cells were cultured and treated with miR-155 inhibitor and an MTT assay was performed to determine the role of miR-155 on the proliferation of MCF-7 cells. Subsequently, TGFBR2 and epithelial-mesenchymal transition (EMT)-associated molecules were analyzed using RT-qPCR and western blot assays. The direct binding of miR-155 to TGFBR2 was validated using a dual luciferase assay. Higher levels of miR-155 and lower levels of TGFBR2 were expressed in human BC tissues compared with paired normal tissues. Furthermore, the expression levels of miR-155 were associated with the tumor size, TNM stage and metastasis status of BC. Transfection of MCF-7 cells with miR-155 inhibitors resulted in reduced cell proliferation and suppressed the EMT process, characterized by upregulated expression of the epithelial markers, E-cadherin and CK18, and downregulated expression of mesenchymal markers, fibronectin and smooth muscle actin α. Transfection of a miR-155 inhibitor also resulted in increased expression of TGFBR2, and miR-155 may have regulated TGFBR2 through direct binding to the 3'untranslated region of TGFBR2 as determined using a dual-luciferase assay. Based on the results of the present study, miR-155 may serve as a novel diagnostic biomarker and therapeutic target for patients with BC.

Platelets promote breast cancer cell MCF-7 metastasis by direct interaction: surface integrin \u03b12\u03b21-contacting-mediated activation of Wnt-\u03b2-catenin pathway

BackgroundIntegrin-mediated platelet-tumor cell contacting plays an important role in promoting epithelial-mesenchymal transition (EMT) transformation of tumor cells and cancer metastasis, but whether it occurs in breast cancer cells is not completely clear.ObjectiveThe purpose of this study was to investigate the role of integrin α2β1 in platelet contacting to human breast cancer cell line MCF-7 and its effect on the EMT and the invasion of MCF-7 cells.MethodsHuman platelets were activated by thrombin, and separated into pellets and releasates before the co-incubation with MCF-7 cells. Cell invasion was evaluated by transwell assay. The surface integrins on pellets and MCF-7 cells were inhibited by antibodies. The effect of integrin α2β1 on Wnt-β-catenin pathway was assessed by integrin α2β1-silencing and Wnt-β-catenin inhibitor XAV. The therapeutic effect of integrin α2β1-silencing was confirmed in the xenograft mouse model.ResultsPellets promote the invasion and EMT of MCF-7 cells via direct contacting of surface integrin α2β1. The integrin α2β1 contacting activates Wnt-β-catenin pathway and promotes the expression of EMT proteins in MCF-7 cells. The activated Wnt-β-catenin pathway also promotes the autocrine of TGF-β1 in MCF-7 cells. Both Wnt-β-catenin and TGF-β1/pSmad3 pathways promote the expression of EMT proteins. Integrin α2β1-silencing inhibits breast cancer metastasis in vivo.ConclusionsThe direct interaction between platelets and tumor cells exerts its pro-metastatic function via surface integrin α2β1 contacting and Wnt-β-catenin activation. Integrin α2β1-silencing has the potential effect of inhibiting breast cancer metastasis.

Platelets Promote Breast Cancer Cell MCF-7 Metastasis by Direct Interaction: Surface Integrin α2β1 Contacting Mediated Activation of Wnt-β-Catenin Pathway

Background: Integrin-mediated platelet-tumor cell contacting plays an important role in promoting epithelial-mesenchymal transition (EMT) transformation of tumor cells and cancer metastasis, but whether it occurs in breast cancer cells is not completely clear. Objective: The purpose of this study was to investigate the role of integrin α2β1 in platelet contacting to human breast cancer cell line MCF-7 and its effect on the EMT and the invasion of MCF-7 cells. Methods: Human platelets were activated by thrombin, and separated into pellets and releasates before the co-incubation with MCF-7 cells. Cell invasion was evaluated by transwell assay. The surface integrins on pellets and MCF-7 cells were inhibited by antibodies. The effect of integrin α2β1 on Wnt-β-catenin pathway was assessed by integrin α2β1-silencing and Wnt-β-catenin inhibitor XAV. The therapeutic effect of integrin α2β1-silencing was confirmed in the xenograft mouse model. Results: Pellets promote the invasion and EMT of MCF-7 cells via direct contacting of surface integrin α2β1. The integrin α2β1 contacting activates Wnt-β-catenin pathway and promotes the expression of EMT proteins in MCF-7 cells. The activated Wnt-β-catenin pathway also promotes the autocrine of TGF-β1 in MCF-7 cells. Both Wnt-β-catenin and TGF-β1/pSmad3 pathways promote the expression of EMT proteins. Integrin α2β1-silencing inhibits breast cancer metastasis in vivo. Conclusions: The direct interaction between platelets and tumor cells exerts its pro-metastatic function via surface integrin α2β1 contacting and Wnt-β-catenin activation. Integrin α2β1-silencing has the potential effect of inhibiting breast cancer metastasis. Funding: This study was supported by the National Natural Science Foundation of China (Grant No. 81702595). Declaration of Interest: All authors declare that they have no competing interests. Ethical Approval: This study was approved by the Institute Research Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University. All the individuals were participating in this study with written informed consent. All animals-treatment operations were executed according to the Zhengzhou University Ethical Guidelines for Animal Experiment.

Propofol inhibits proliferation and epithelial-mesenchymal transition of MCF-7 cells by suppressing miR-21 expression

Breast cancer is a common malignant tumor with a high incidence of recurrence and metastasis. It has been reported that propofol has certain anti-breast cancer effects, but the intrinsic molecular mechanism remains unclear. This study investigated the effect of propofol on breast cancer MCF-7 cells and its possible regulatory mechanisms. MCF-7 cells were treated by propofol, and then the effects of propofol on cell growth and epithelial-mesenchymal transition (EMT) were studied. We subsequently testified whether miR-21 was a downstream effector of propofol. As a result, propofol repressed the proliferation and migration of MCF-7 cells, but significantly induced apoptosis. Meanwhile, miR-21 expression and EMT were inhibited by propofol stimulation. The effects of propofol on MCF-7 cells proliferation, apoptosis and EMT were all attenuated when miR-21 was overexpressed. Besides this, the activation of PI3K/AKT and Wnt3a/β-catenin pathways was reduced by propofol stimulation in a miR-21-depedent manner. In conclusion, propofol can inhibit the proliferation and EMT of MCF-7 cells by down-regulating miR-21 expression. Moreover, miR-21 can further regulate PI3K/AKT and Wnt/β-catenin pathways.

Influence of autocrine growth hormone on NF-κB activation leading to epithelial-mesenchymal transition of mammary carcinoma.

Progression of breast cancers often depends on hormones among which human growth hormone is prominently involved in breast cancer progression. Earlier studies have reported constitutive activation of nuclear factor-κB, a key regulator of growth hormone receptor-mediated signaling pathway in breast carcinoma, but the precise molecular mechanisms are still elusive. In this study, we investigated the effect of human growth hormone on nuclear factor-κB activation and epithelial-mesenchymal transition in breast carcinoma. Our results explored that autocrine production of human growth hormone enhances cellular proliferation by the activation of nuclear factor-κB (65 kDa) and downregulation of E-cadherin expression. Furthermore, enhanced nuclear factor-κB expression significantly increases cell proliferation and diminishes apoptosis in MCF-7 cell line. Increased expression of nuclear factor-κB significantly enhances mammary carcinoma cell migration and invasion stimulated by autocrine human growth hormone, which results in epithelial-mesenchymal transition of MCF-7 cells. In conclusion, our study revealed the influence of human growth hormone on nuclear factor-κB activity and epithelial-mesenchymal transition in mammary carcinoma. Our findings will help to understand molecular role of "growth hormone-nuclear factor-κB axis" in mammary carcinogenesis which may facilitate the discovery of suitable pathway inhibitors for disease treatment.

Regulation of matrix stiffness on the epithelial-mesenchymal transition of breast cancer cells under hypoxia environment

Substrate stiffness and hypoxia are associated with tumor development and progression, respectively. However, the synergy of them on the biological behavior of human breast cancer cell is still largely unknown. This study explored how substrate stiffness regulates the cell phenotype, viability, and epithelial-mesenchymal transition (EMT) of human breast cancer cells MCF-7 under hypoxia (1% O2). TRITC-phalloidin staining showed that MCF-7 cells transformed from round to irregular polygon with stiffness increase either in normoxia or hypoxia. While being accompanied with the upward tendency from a 0.5- to a 20-kPa substrate, the percentage of cell apoptosis was significantly higher in hypoxia than that in normoxia, especially on the 20-kPa substrate. Additionally, it was hypoxia, but not normoxia, that promoted the EMT of MCF-7 by upregulating hypoxia-inducible factor-1α (HIF-1α), vimentin, Snail 1, and matrix metalloproteinase 2 (MMP 2) and 9 (MMP 9), and downregulating E-cadherin simultaneously regardless of the change of substrate stiffness. In summary, this study discovered that hypoxia and stiffer substrate (20kPa) could synergistically induce phenotype change, apoptosis, and EMT of MCF-7 cells. Results of this study have an important significance on further exploring the synergistic effect of stiffness and hypoxia on the EMT of breast cancer cells and its molecular mechanism.

Secretome of tumor-associated leukocytes augment epithelial-mesenchymal transition in positive lymph node breast cancer patients via activation of EGFR/Tyr845 and NF-κB/p65 signaling pathway.

Epithelial-mesenchymal transition (EMT) is an essential process in breast cancer metastasis. The aim of the present study was to determine the role of secretions of tumor-associated leukocytes (TALs) isolated from negative and positive lymph nodes (nLNs and pLNs, respectively) breast cancer patients in regulating EMT mechanism and the associated signaling pathways. We found an increased infiltration of TALs, which was associated with downregulation of E-cadherin and over-expression of vimentin in the breast carcinoma tissues of pLNs as compared to nLNs patients and normal breast tissues obtained from healthy volunteers during mammoplasty. Furthermore, TALs isolated from pLNs breast cancer patients secreted an elevated panel of cytokines by up to 2-5-fold when compared with those isolated from nLNs patients. Secretome of TALs of pLNs possessed higher TARC, IGF-1, IL-3, TNF-β, IL-5, G-CSF, IL-4, and IL-1α with more than a fivefold compared to those of nLNs. Using the human breast cancer cell lines MCF-7 and MDA-MB-231, we found that cytokines secreted by TALs isolated from nLNs and pLNs breast cancer patients promoted EMT via upregulation of TGF-β and vimentin and downregulation of E-cadherin at messenger RNA (mRNA) levels in both cell lines and at protein level in MCF-7. While TGF-β is over-expressed by MDA-MB-231 seeded in media conditioned by secretome of TALs isolated from nLNs and pLNs breast cancer patients. The downstream TGF-β signaling transcription factors, Snail, Slug, and Twist, known to be associated with EMT mechanism were over-expressed by MCF-7 and MDA-MB-231 seeded in media conditioned by secretome of TALs isolated from nLNs and pLNs breast cancer patients. Acquisition of EMT in MCF-7 cells is mechanistically attributed to the activation of EGFR(Tyr845) and NF-κB/p65(Ser276) signaling which are significantly highly expressed by MCF-7 cells seeded in media conditioned by secretome of TALs isolated from pLNs compared to nLNs patients. Overall, this study provides implications of secretome of TALs and activated EGFR(Tyr845) and NF-κB/p65(Ser276) in EMT process that may be considered a therapeutic strategy to inhibit lymph node metastasis in breast cancer patients.

MCP-1-induced ERK/GSK-3β/Snail signaling facilitates the epithelial-mesenchymal transition and promotes the migration of MCF-7 human breast carcinoma cells.

Monocyte chemoattractant protein-1 (MCP-1) is a chemotactic cytokine that can bind to its receptor cysteine-cysteine chemokine receptor 2 (CCR2) and plays an important role in breast cancer cell metastasis. However, the molecular mechanisms underlying MCP-1-induced alterations in cellular functions during tumor progression are poorly understood. Here, we showed that MCP-1 stimulated the epithelial-mesenchymal transition (EMT) and induced the tumorigenesis of breast cancer cells by downregulating E-cadherin, upregulating vimentin and fibronectin, activating matrix metallopeptidase-2 (MMP-2), and promoting migration and invasion. Moreover, MCP-1 treatment reduced glycogen synthase kinase-3β (GSK-3β) activity via the MEK/ERK-mediated phosphorylation of serine-9 in MCF-7 cells. The inhibition of MEK/ERK by U0126 attenuated the MCP-1-induced phosphorylation of GSK-3β and decreased the expression of Snail, an EMT-related transcription factor, leading to the inhibition of MCF-7 cell migration and invasion. Inactivation of GSK-3β by LiCl (lithium chloride) treatment notably increased MMP-2 activity, vascular endothelial growth factor expression and EMT of MCF-7 cells. These findings revealed that MCP-1-induced EMT and migration are mediated by the ERK/GSK-3β/Snail pathway, and identified a potential novel target for therapeutic intervention in breast cancer.

IGF-1-induced epithelial–mesenchymal transition in MCF-7 cells is mediated by MUC1

Metastases are the major cause of death from cancer. IGF-1 signaling pathway has been shown to have strong implication in the epithelial–mesenchymal transition (EMT) process. However, the mechanisms of how IGF-1 promotes EMT have not been fully elucidated. Mucin 1 (MUC1), a transmembrane glycoprotein, engages in multiple cancer-related signaling pathways and functions as an oncoprotein that contributes to metastases. Here we provide evidence showing that IGF-1 upregulates MUC1 expression in MCF-7 cells in a PI3K/Akt signaling pathway-dependent manner. The overexpression of MUC1 is critical for IGF-1-induced EMT of MCF-7 cells because the knockdown of MUC1 prevented the EMT of MCF-7 cells as demonstrated by various EMT markers including the expression of E-cadherin, N-cadherin, vimentin, fibronectin and the nuclear translocalization of β-catenin. On the other hand, the knockdown of MUC1 had no impact on IGF-1-induced activation of PI3K/Akt or MAPK. In summary, our study demonstrated MUC1 as a critical downstream effector that mediates IGF-1-induced EMT of MCF-7 cells and suggested that MUC1 might be a potential therapeutic target for preventing tumor metastases.

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.

Low doses ionizing radiation enhances the invasiveness of breast cancer cells by inducing epithelial–mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a process cellular morphologic and molecular alterations facilitate cell invasion. We hypothesized that low dose ionizing irradiation (LDIR) enhances the invasiveness of breast cancer cells by inducing EMT. The effects of LDIR on cellular morphology and the EMT markers of MCF-7 breast cancer cells were analyzed by western blot/RT-PCR and migration/invasion was examined using the transwell assay. We found that LDIR led to the phenotypic changes of EMT in MCF-7 cells and down-regulation of epithelial differentiation markers and transcriptional induction of mesenchymal markers. Furthermore, the radiated cells demonstrated enhanced migration/invasion MCF-7 cells compared with non-radiated cells. In summary, LDIR promotes the invasiveness of breast cancer cells through epithelial to mesenchymal transition. These findings may ultimately provide a new targeted approach for improving the therapeutic effectiveness of radiation in breast cancer.

Role of nuclear factor kappa B and reactive oxygen species in the tumor necrosis factor-a-induced epithelial-mesenchymal transition of MCF-7 cells

The microenvironment of the tumor plays an important role in facilitating cancer progression and activating dormant cancer cells. Most tumors are infiltrated with inflammatory cells which secrete cytokines such as tumor necrosis factor-alpha (TNF-alpha). To evaluate the role of TNF-alpha in the development of cancer we studied its effects on cell migration with a migration assay. The migrating cell number in TNF-alpha-treated group is about 2-fold of that of the control group. Accordingly, the expression of E-cadherin was decreased and the expression of vimentin was increased upon TNF-alpha treatment. These results showed that TNF-alpha can promote epithelial-mesenchymal transition (EMT) of MCF-7 cells. Further, we found that the expression of Snail, an important transcription factor in EMT, was increased in this process, which is inhibited by the nuclear factor kappa B (NFkappaB) inhibitor aspirin while not affected by the reactive oxygen species (ROS) scavenger N-acetyl cysteine. Consistently, specific inhibition of NFkappaB by the mutant IkappaBalpha also blocked the TNF-alpha-induced upregulation of Snail promoter activity. Thus, the activation of NFkappaB, which causes an increase in the expression of the transcription factor Snail is essential in the TNF-alpha-induced EMT. ROS caused by TNF-alpha seemed to play a minor role in the TNF-alpha-induced EMT of MCF-7 cells, though ROS per se can promote EMT. These findings suggest that different mechanisms might be responsible for TNF-alpha- and ROS-induced EMT, indicating the need for different strategies for the prevention of tumor metastasis induced by different stimuli.