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Induction and Analysis of Epithelial to Mesenchymal Transition
Published on: August 27, 2013
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Mutant PIK3CA Induces EMT in a Cell Type Specific Manner
Divya Bhagirath1, Xiangshan Zhao1, Sameer Mirza1
1Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
Plos One
|December 13, 2016
Summary
Mutant PIK3CA, Ras, and p53 oncogenes transform breast stem cells. The epithelial-to-mesenchymal transition (EMT) varies by cell type but doesn't solely dictate oncogenesis or tumor-initiating cell expansion.
Area of Science:
- Cancer Biology
- Molecular Oncology
- Stem Cell Research
Background:
- Breast cancer subtypes exhibit differential gene expression linked to patient survival outcomes.
- PIK3CA mutations are prevalent across breast cancer subtypes and linked to tumor heterogeneity and reduced survival in basal subtypes.
- Understanding PIK3CA-induced oncogenesis and heterogeneity is crucial for targeted therapies.
Purpose of the Study:
- To investigate the combined effect of mutant PIK3CA, Ras, and p53 on the oncogenic behavior of distinct breast stem/progenitor cell lines.
- To analyze the role of epithelial-to-mesenchymal transition (EMT) in PIK3CA-driven oncogenesis and tumor heterogeneity.
- To assess the impact of these oncogenes on tumor-initiating cell populations and in-vivo tumorigenesis.
Main Methods:
- Ectopic overexpression of mutant Ras, p53, and PIK3CA constructs in two distinct breast stem/progenitor cell lines (K5+/K19- and K5+/K19+).
- In-vitro analyses including anchorage-independent soft agar colony formation assay and assessment of epithelial-to-mesenchymal transition (EMT).
- In-vivo studies involving xenotransplantation in mice to evaluate tumorigenesis, EMT maintenance, and tumor-initiating cell populations (CD44+/CD24low).
Main Results:
- The oncogene combination (m-Ras/m-p53/m-PIK3CA) efficiently transformed both K5+/K19- and K5+/K19+ cell lines in-vitro.
- A complete EMT was observed in K5+/K19- cells, while K5+/K19+ cells showed a predominantly epithelial phenotype with minor EMT.
- Both transformed cell lines exhibited increased invasion, migration, and in-vivo tumorigenesis, maintaining their respective EMT/epithelial phenotypes. K5+/K19- cells showed a higher proportion of tumor-initiating CD44+/CD24low cells.
Conclusions:
- The oncogenic transformation and subsequent tumor development are influenced by the specific cell type, as evidenced by differential EMT.
- Epithelial-to-mesenchymal transition (EMT) is a cell-type-dependent phenomenon and does not solely dictate oncogenesis.
- Combined mutations in PIK3CA, Ras, and p53 can drive tumorigenesis and expand tumor-initiating cell populations in a context-dependent manner.
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