Membrane-Initiated Estradiol Signaling of Epithelial-Mesenchymal Transition-Associated Mechanisms Through Regulation of Tight Junctions in Human Breast Cancer Cells

Abstract

Tumor cells utilize inappropriate epithelialmesenchymal transition (EMT) mechanisms during the invasive process. It is becoming increasingly clear that estradiol (E2) induces breast cancer cell progression and enhances EMT; however, the mechanisms associated with this are unclear. We investigated the role of E2 on the expression and intracellular localization of the tight junction (TJ)-associated proteins, zonula occluden 1 (ZO-1), ZO-1-associated nucleic acid binding (ZONAB), and occludin, on the activation of cSrc and human epidermal growth factor receptor 2 (HER2) expression and cellular migration in the estrogen receptor (ER)-positive breast cancer cell lines, MCF-7 and T47D. WeNovelty and Impact Statements We demonstrated that estrogen is able to induce tight junction (TJ) disruption in two breast cancer cell lines through the activation of c-Src. Ablated expression of the novel epithelial marker CRB3 could lead to increased cell migration. Based on our findings, we propose a novel estrogen-induced TJ pathway associated with breast cancer cell motility and, eventually, to metastasis. demonstrated that 1 nM E2 elicits c-Src activation after 15 min. The p-Src/ZO-1 complex led to ZO-1 and ZONAB disruption at the TJ and increased expression of HER2 mRNAs. These changes correlate with decreased expression of the epithelial markers occludin and CRB3 and increased synthesis of N-cadherin. This led to increased MCF-7 cell migration induced by E2, even in the presence of a cell proliferation inhibitor. Incubation with ICI 182,780 (Fulvestrant), an ER antagonist, precluded the effects of E2 on c-Src phosphorylation, p-Src/ZO-1 complex formation, ZO-1/ZONAB nuclear translocation, and migration of MCF-7 cells. Our findings suggest that E2 promotes TJ disruption during tumor progression and increases cell motility. We propose a novel pathway where estrogens promote EMTassociated mechanisms that possibly lead to metastasis.

Role of Epithelial-Mesenchyme Transition in Chlamydia Pathogenesis

“…The role of chlamydia-inducible, cytokines such as TNF-alpha and TGF-beta in EMT and fibrosis has been well established [ 86 ]. Thus, the ability of estrogen to induce EMT involving miRNA alterations [ 87 ], and our results showing that chlamydia induced EMT and estrogen receptors, would suggest that chlamydia may induce EMT via the estrogen receptor-signaling pathway. Consistent with the miRNA profiles and up-regulation of pro-EMT proteins, our results further showed that the chlamydial down-regulated proteins are those that maintain epithelial integrity, support reproductive fertility, control fibrosis and act as tumor suppressors.…”

High tumor budding stratifies breast cancer with metastatic properties

“…Epithelial–mesenchymal transition (EMT), a feature of metastatic cells, has previously been described in the context of tumor budding [ 22 ] and could be consistent with the observed association to both LVI and lymph node positivity but requires further analysis. A recent report also demonstrated that estrogen is involved in EMT in breast cancer cell lines with stem cell properties [ 23 ] and it was shown that estrogen is involved in disruption of tight-junction and increased cell motility [ 24 ]. We suspect that ER-positive tumors with high tumor budding may be undergoing a high degree of EMT and therefore have more metastatic potential.…”

The relationship between tumour budding, the tumour microenvironment and survival in patients with invasive ductal breast cancer

“…The basis of these observations is not clear. However, it was recently reported that oestrogen is involved in EMT in breast cancer cell lines with stem cell properties ( Sun et al , 2014 ) and that oestrogen is involved in disruption of tight junction and increased cell motility ( Sanchez et al , 2010 ; Jiménez-Salazar et al , 2014 ). Therefore, this may suggest that ER-positive tumours with high tumour budding may be undergoing a higher degree of EMT and as a result more metastatic potential.…”