Journal Article

Transforming growth factor-β-induced epithelial–mesenchymal transition facilitates epidermal growth factor-dependent breast cancer progression

Smith, J A, Schiemann, W P, Wendt, M K

2010

Overview

Transforming growth factor-β (TGF-β) and epidermal growth factor (EGF) have critical roles in regulating the metastasis of aggressive breast cancers, yet the impact of epithelial–mesenchymal transition (EMT) induced by TGF-β in altering the response of breast cancer cells to EGF remains unknown. We show in this study that murine metastatic 4T1 breast cancer cells formed compact and dense spheroids when cultured under three-dimensional (3D) conditions, which was in sharp contrast to the branching phenotypes exhibited by their nonmetastatic counterparts. Using the human MCF10A series, we show that epithelial-type and nonmetastatic breast cancer cells were unable to invade to EGF, whereas their mesenchymal-type and metastatic counterparts readily invaded to EGF. Furthermore, EMT induced by TGF-β was sufficient to manifest dense spheroid morphologies, a phenotype that increased primary tumor exit and invasion to EGF. Post-EMT invasion to EGF was dependent on increased activation of EGF receptor (EGFR) and p38 mitogen-activated protein kinase, all of which could be abrogated either by pharmacologic (PF-562271) or by genetic (shRNA) targeting of focal adhesion kinase (FAK). Mechanistically, EMT induced by TGF-β increased cell-surface levels of EGFR and prevented its physical interaction with E-cadherin, leading instead to the formation of oncogenic signaling complexes with TβR-II. Elevated EGFR expression was sufficient to transform normal mammary epithelial cells, and to progress their 3D morphology from that of hollow acini to branched structures characteristic of nonmetastatic breast cancer cells. Importantly, we show that TGF-β stimulation of EMT enabled this EGFR-driven breast cancer model to abandon their inherent branching architecture and form large, undifferentiated masses that were hyperinvasive to EGF and showed increased pulmonary tumor growth upon tail vein injection. Finally, chemotherapeutic targeting of FAK was sufficient to revert the aggressive behaviors of these structures. Collectively, this investigation has identified a novel EMT-based approach to neutralize the oncogenic activities of EGF and TGF-β in aggressive and invasive forms of breast cancer.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/67/322 / 631/80/84/2176 / 692/699/67/1347 / Animals / Apoptosis / Biological and medical sciences / Breast cancer / Breast Neoplasms - drug therapy / Breast Neoplasms - metabolism / Breast Neoplasms - pathology / Cadherins - metabolism / Carcinoma - drug therapy / Carcinoma - metabolism / Carcinoma - secondary / Cell Biology / Cell Line, Tumor / Cell physiology / Cell surface / Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes / Cytology / Development and progression / E-cadherin / Epidermal growth factor / Epidermal Growth Factor - metabolism / Epidermal Growth Factor - pharmacology / Epidermal growth factor receptors / Epithelial cells / Epithelial-Mesenchymal Transition / ErbB Receptors - metabolism / Female / Focal adhesion kinase / Focal Adhesion Protein-Tyrosine Kinases - metabolism / Fundamental and applied biological sciences. Psychology / Gynecology. Andrology. Obstetrics / Human Genetics / Humans / Indoles - pharmacology / Internal Medicine / Invasiveness / Kinases / Mammary gland / Mammary gland diseases / Mammary Neoplasms, Experimental - drug therapy / Mammary Neoplasms, Experimental - metabolism / Mammary Neoplasms, Experimental - pathology / MAP kinase / Medical sciences / Medicine / Medicine & Public Health / Mesenchyme / Metastases / Metastasis / Mice / Molecular and cellular biology / Oncology / original-article / p38 Mitogen-Activated Protein Kinases - metabolism / Phenotypes / Physiological aspects / Protein kinase / Receptors, Transforming Growth Factor beta - metabolism / RNA, Small Interfering - metabolism / Spheroids / Sulfonamides - pharmacology / Transforming Growth Factor beta - metabolism / Transforming Growth Factor beta - pharmacology / Transforming growth factor-b / Transforming growth factors / Tumors