Mesenchymal to Epithelial Transition (MET)

Definition

Mesenchymal to Epithelial Transition (MET) is a biological process where cells change from a mesenchymal phenotype, characterized by a migratory and invasive behavior, to an epithelial phenotype, which is more organized and adherent. This transition plays a critical role in various developmental processes, including tissue regeneration, organ development, and cancer progression, highlighting its importance in both normal physiology and disease.

5 Must Know Facts For Your Next Test

1. MET is essential during embryonic development as it allows mesenchymal progenitor cells to form structured epithelial tissues.
2. This transition is often accompanied by changes in gene expression patterns, particularly the upregulation of epithelial markers like E-cadherin.
3. In cancer biology, MET can contribute to the formation of secondary tumors by enabling cancer cells to revert to a less invasive state while still maintaining proliferative capabilities.
4. Growth factors and extracellular matrix components are key signals that trigger MET by influencing the cellular microenvironment.
5. Dysregulation of MET can lead to various pathologies, including fibrosis and tumor progression, making it a critical area of research in developmental biology and oncology.

Review Questions

• How does MET differ from EMT in terms of cellular characteristics and outcomes?
  • MET and EMT represent opposite transitions of cellular behavior. While MET involves the transition from a mesenchymal phenotype, which is characterized by increased mobility and invasion, back to an epithelial phenotype that is more structured and adherent, EMT facilitates the opposite shift. Understanding these processes is crucial as they play significant roles in development and cancer progression, influencing how cells interact within their environments.
• Discuss the significance of cadherins in the mesenchymal to epithelial transition.
  • Cadherins are vital for establishing and maintaining cell-cell adhesion in epithelial tissues. During MET, the expression of E-cadherin increases while N-cadherin levels decrease, helping cells to re-establish tight junctions and organized layers. This transition is essential for forming cohesive epithelial structures that are crucial for proper tissue function and integrity after developmental or injury-related changes.
• Evaluate the potential implications of dysregulated MET in cancer treatment strategies.
  • Dysregulated MET can have significant implications for cancer treatment as it may facilitate metastasis or lead to therapy resistance. Understanding how cancer cells can undergo MET provides insights into their ability to evade targeted therapies that focus on inhibiting EMT pathways. Therefore, targeting the factors that control MET could offer novel therapeutic strategies to prevent tumor spread or re-sensitize resistant cancers by manipulating their transition states.

Related terms

Epithelial-Mesenchymal Transition (EMT): The process where epithelial cells lose their characteristics and gain mesenchymal traits, allowing them to become more migratory and invasive.

Cell Plasticity: The ability of cells to change their phenotype in response to environmental cues, which is fundamental in processes like development, repair, and cancer metastasis.

Cadherins: A class of proteins that mediate cell-cell adhesion in epithelial tissues, playing a key role in maintaining the integrity of epithelial layers during MET.