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 2

Opposing phenotypes and distinct gene programs expressed by 2 clonal populations derived from PC-3 cells.

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Opposing phenotypes and distinct gene programs expressed by 2 clonal ...
(A) PC-3/Mc cells grew with short doubling times (22–24 hours), while PC-3/S cells grew with long doubling times (60–72 hours). (B) PC-3/Mc, but not PC-3/S, cells displayed robust anchorage-independent growth. Cells (103) seeded in low-attachment plates in the presence of 0.5% methyl cellulose were scored for spheroids after 14 days (triplicate assays). (C) PC-3/Mc cells were barely invasive, while PC-3/S cells were highly invasive. Cells seeded on the upper chamber of Matrigel- and hyaluronic acid–coated Transwell units were scored for invading cells after 24 hours (triplicate assays). (D) PC-3/Mc cells expressed higher levels than PC-3/S cells of E-cadherin and EpCAM. PC-3/S cells expressed higher levels than PC-3/Mc cells of fibronectin, vimentin, and SPARC, by Western blotting. (E) PC-3/Mc cells expressed higher levels than PC-3/S cells of genes associated with self renewal and pluripotency. PC-3/S cells expressed higher levels than PC-3/Mc cells of genes associated with mesenchymal phenotypes and EMT. Relative transcript levels are represented as the log10 of ratios between the 2 cell lines of their 2–ΔΔCp real-time PCR values. (F) PC-3/S cells were more motile than PC-3/Mc cells in wound-healing assays (triplicate assays). Parentheses denote percentages of FBS. (G) PC-3/Mc cells were round and expressed membrane-associated E-cadherin and nuclear SOX2. PC-3/S cells were flat and spindled and with undetectable E-cadherin. Scale bar: 20 μm. (H) Gene-set enrichment analysis (GSEA) showing significant enrichment in PC-3/Mc cells of the ESC-like, MYC, ES1, and ES2 gene modules. FDR q, false discovery rate q value; NES, normalized enrichment score; ES, enrichment score. Results are expressed as mean ± SEM. **P < 0.01; ***P < 0.001.