Epithelial-mesenchymal transition can suppress major attributes of human epithelial tumor-initiating cells
Toni Celià-Terrassa, … , Pedro L. Fernández, Timothy M. Thomson
Toni Celià-Terrassa, … , Pedro L. Fernández, Timothy M. Thomson
Published April 16, 2012
Citation Information: J Clin Invest. 2012;122(5):1849-1868. https://doi.org/10.1172/JCI59218.
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Research Article Oncology

Epithelial-mesenchymal transition can suppress major attributes of human epithelial tumor-initiating cells

Abstract

Malignant progression in cancer requires populations of tumor-initiating cells (TICs) endowed with unlimited self renewal, survival under stress, and establishment of distant metastases. Additionally, the acquisition of invasive properties driven by epithelial-mesenchymal transition (EMT) is critical for the evolution of neoplastic cells into fully metastatic populations. Here, we characterize 2 human cellular models derived from prostate and bladder cancer cell lines to better understand the relationship between TIC and EMT programs in local invasiveness and distant metastasis. The model tumor subpopulations that expressed a strong epithelial gene program were enriched in highly metastatic TICs, while a second subpopulation with stable mesenchymal traits was impoverished in TICs. Constitutive overexpression of the transcription factor Snai1 in the epithelial/TIC-enriched populations engaged a mesenchymal gene program and suppressed their self renewal and metastatic phenotypes. Conversely, knockdown of EMT factors in the mesenchymal-like prostate cancer cell subpopulation caused a gain in epithelial features and properties of TICs. Both tumor cell subpopulations cooperated so that the nonmetastatic mesenchymal-like prostate cancer subpopulation enhanced the in vitro invasiveness of the metastatic epithelial subpopulation and, in vivo, promoted the escape of the latter from primary implantation sites and accelerated their metastatic colonization. Our models provide new insights into how dynamic interactions among epithelial, self-renewal, and mesenchymal gene programs determine the plasticity of epithelial TICs.

Authors

Toni Celià-Terrassa, Óscar Meca-Cortés, Francesca Mateo, Alexia Martínez de Paz, Nuria Rubio, Anna Arnal-Estapé, Brian J. Ell, Raquel Bermudo, Alba Díaz, Marta Guerra-Rebollo, Juan José Lozano, Conchi Estarás, Catalina Ulloa, Daniel ρlvarez-Simón, Jordi Milà, Ramón Vilella, Rosanna Paciucci, Marian Martínez-Balbás, Antonio García de Herreros, Roger R. Gomis, Yibin Kang, Jerónimo Blanco, Pedro L. Fernández, Timothy M. Thomson

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Figure 4

Overexpression of Snai1 in PC-3/Mc cells induces EMT and suppresses anchorage-independent growth and the expression of a self-renewal gene program.

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Overexpression of Snai1 in PC-3/Mc cells induces EMT and ...
(A) Overexpression of Snai1, Twist1, or TWIST2 in PC-3/Mc cells induced a fibroblastoid morphology and a downregulation of membrane-associated E-cadherin. Cells were transduced with retroviruses for the expression of mouse Snai1 or Twist1 or human TWIST2. Controls were PC-3/Mc cells transduced with pBABE and selected for puromycin resistance. Scale bars: 20 μm. (B) Overexpression of Snai1 strongly induced the invasiveness of PC-3/Mc cells, with a moderate effect by Twist1 or TWIST2. (C) Overexpression of Snai1 strongly inhibited spheroid growth by PC-3/Mc cells, with a moderate effect by TWIST2. (D) Overexpression of Snai1 in PC-3/Mc cells caused a strong downregulation of cell-surface E-cadherin, with a moderate effect by Twist1 or TWIST2, as determined by flow cytometry. (E) Overexpression of Snai1 in PC-3/Mc cells induced a downregulation of E-cadherin and EpCAM, a modest downregulation of SOX2 and MYC, and an upregulation of fibronectin and SPARC, as determined by Western blotting. Overexpression of Twist1 or TWIST2 induced a moderate downregulation of E-cadherin. (F) Overexpression of Snai1 and, more moderately, Twist1 or TWIST2, caused a downregulation of self-renewal and epithelial genes and an upregulation of mesenchymal genes. Relative transcript levels are represented as the log10 of ratios between experimental and control cells of their 2–ΔΔCp real-time PCR values. The levels of SNAI1 correspond to the endogenous, human transcripts, downregulated by overexpression of the exogenous (mouse) Snai1. Asterisk in F indicates that values for ectopic TWIST2 are off scale. Results are expressed as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001.