Epidermal Growth Factor Receptor Cooperates with Signal Transducer and Activator of Transcription 3 to Induce Epithelial-Mesenchymal Transition in Cancer Cells via Up-regulation of TWIST Gene Expression

Abstract

Aberrant epidermal growth factor receptor (EGFR) signaling is a major cause of tumor progression and metastasis; the underlying mechanisms, however, are not well understood. In particular, it remains elusive whether deregulated EGFR pathway is involved in epithelial-mesenchymal transition (EMT), an early event that occurs during metastasis of cancers of an epithelial origin. Here, we show that EGF induces EGFRexpressing cancer cells to undergo a transition from the epithelial to the spindle-like mesenchymal morphology. EGF reduced E-cadherin expression and increased that of mesenchymal proteins. In search of a downstream mediator that may account for EGF-induced EMT, we focused on transcription repressors of E-cadherin, TWIST, SLUG, and Snail and found that cancer cells express high levels of TWIST and that EGF enhances its expression. EGF significantly increases TWIST transcripts and protein in EGFR-expressing lines. Forced expression of EGFR reactivates TWIST expression in EGFR-null cells. TWIST expression is suppressed by EGFR and Janusactivated kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) inhibitors, but not significantly by those targeting phosphoinositide-3 kinase and MEK/ERK. Furthermore, constitutively active STAT3 significantly activates the TWIST promoter, whereas the JAK/STAT3 inhibitor and dominant-negative STAT3 suppressed TWIST promoter. Deletion/mutation studies further show that a 26-bp promoter region contains putative STAT3 elements required for the EGFresponsiveness of the TWIST promoter. Chromatin immunoprecipitation assays further show that EGF induces binding of nuclear STAT3 to the TWIST promoter. Immunohistochemical analysis of 130 primary breast carcinomas indicates positive correlations between non-nuclear EGFR and TWIST and between phosphorylated STAT3 and TWIST. Together, we report here that EGF/EGFR signaling pathways induce cancer cell EMT via STAT3-mediated TWIST gene expression. [Cancer Res 2007;67(19):9066-76]

Sorafenib inhibits transforming growth factor β1-Mediated Epithelial-Mesenchymal Transition and apoptosis in mouse hepatocytes

“…Members of the STAT family, particularly STAT3, have been shown to be essential signal transducers during EMT via their transcriptional activities. 30 Because STAT3 was activated in response to a TGF-b stimulus, 31 we investigated whether sorafenib blocked TGF-b1-induced EMT and apoptosis through the regulation of STAT3 activation. To address this possibility we first validated the expression profile of STAT3 phosphorylation during hepatocyte EMT.…”

Differential roles of ERK and Akt pathways in regulation of EGFR-mediated signaling and motility in prostate cancer cells

“…Although considerable data support a role of receptor tyrosine kinases, including EGFR, in the induction of EMT (Thiery, 2002;Conacci-Sorrell et al, 2003;Lu et al, 2003;Cavallaro and Christofori, 2004;Lo et al, 2007), there remains little consensus about which downstream pathways are necessary to mediate EGFR-induced EMT. Studies within carcinoma cell lines from disparate epithelial tissues have supplied evidence for several different signaling pathways (b-catenin-TCF/LEF-1, ERK, STAT3), as well as alternate repressors of E-cadherin transcription (Twist, Slug) involved in activation of EMT (Conacci-Sorrell et al, 2003;Lu et al, 2003;Lo et al, 2007), reflective of the fact that cancer cells can use completely distinct pathways under diverse biological contexts.…”

“…Studies within carcinoma cell lines from disparate epithelial tissues have supplied evidence for several different signaling pathways (b-catenin-TCF/LEF-1, ERK, STAT3), as well as alternate repressors of E-cadherin transcription (Twist, Slug) involved in activation of EMT (Conacci-Sorrell et al, 2003;Lu et al, 2003;Lo et al, 2007), reflective of the fact that cancer cells can use completely distinct pathways under diverse biological contexts. Our work in prostate cancer cells, in addition to the study in cervical cancer cells (Lee et al, 2008), adds yet another mechanistic pathway by which carcinoma cells undergo EMT, specifically an EGF/EGFR-mediated EMT pathway through Akt inhibition of GSK3b, followed by stabilization of Snail and downregulation of E-cadherin (EGFR-Akt-GSK3b-Snail-E-cadherin-EMT).…”

Differential effects of two-pore channel protein 1 and 2 silencing in MDA-MB-468 breast cancer cells

“…The MDA-MB-468 breast cancer cell line is a commonly utilized in vitro model for the study of EMT in the context of defining responses to signals from the surrounding tumor microenvironment [11,19,20]. TPC2 but not TPC1 silencing significantly inhibited EGFinduced vimentin expression relative to siNT in MDA-MB-468 cells (Fig.…”

“…A number of triple negative breast cancer cell lines (such as MDA-MB-468 cells) have been used as in vitro models for this subtype. MDA-MB-468 cells belong to the related basal A cell line subgroup [10] and with appropriate stimuli, such as epidermal growth factor (EGF), can undergo an epithelial-mesenchymal transition (EMT), which is associated with a loss of epithelial markers such as E-cadherin and the gain of mesenchymal markers such as vimentin [11].…”