Distinguishing mechanisms underlying EMT tristability

Area of Science:

• Cell biology
• Cancer research
• Systems biology

Background:

• Epithelial-Mesenchymal Transition (EMT) is crucial for development and cancer metastasis.
• EMT involves transitions between epithelial (E), hybrid epithelial/mesenchymal (E/M), and mesenchymal (M) phenotypes.
• The miR-34/SNAIL/miR-200/ZEB1 network is central to EMT, but its dynamics are debated.

Purpose of the Study:

• To evaluate two mathematical models (TCS and CBS) of the EMT regulatory network.
• To reconcile theoretical models with experimental observations of EMT dynamics.
• To determine how the miR-200/ZEB1 module governs transitions between E, E/M, and M phenotypes.

Main Methods:

• Integrated experimental and theoretical approach.
• Analysis of SNAIL and ZEB1 responses to TGF-β.
• Experimental manipulation of SNAIL, ZEB1, and FOXC2 in cell lines (H1975, HMLE).

Main Results:

• Both TCS and CBS models explain the two-step EMT (E→E/M→M) and TGF-β responses.
• ZEB1 levels are intermediate in hybrid E/M cells.
• SNAIL overexpression alone does not induce EMT without ZEB1 and FOXC2.

Conclusions:

• Experimental findings favor the ternary chimera switch (TCS) model.
• The miR-200/ZEB1 pathway acts as a three-way switch for EMT phenotype transitions.