Llgl1 prevents metaplastic survival driven by epidermal growth factor dependent migration

Area of Science:

• Cell Biology
• Cancer Research
• Molecular Biology

Background:

• Loss of Llgl1 (Lethal giant larvae homolog 1) is associated with mesenchymal phenotypes and polarity loss.
• Llgl1 regulates cell identity markers and key signaling pathways.

Purpose of the Study:

• To investigate the fundamental cellular and molecular changes induced by Llgl1 loss.
• To determine the role of Epidermal Growth Factor Receptor (EGFR) in Llgl1-deficient phenotypes.

Main Methods:

• Analysis of cell identity markers (CD44, CD49f, CD24).
• Assessment of TAZ and Slug nuclear translocation.
• Mammosphere formation assays and soft-agar growth.
• Orthotopic transplantation in NOD-SCID mice.
• Lineage tracing and wound healing experiments.
• Investigation of EGFR mislocalization and mutation effects.

Main Results:

• Llgl1 loss induces a fundamental shift in cellular phenotype, promoting mesenchymal characteristics.
• Cells lacking Llgl1 form mammospheres dependent on EGFR for survival and transplantability.
• Enhanced EGF-dependent migration and prolonged survival in orthotopic transplants observed.
• Llgl1 loss drives EGFR mislocalization, which, along with a specific mutation (P667A), activates AKT and TAZ nuclear translocation.

Conclusions:

• Loss of Llgl1 promotes pre-neoplastic changes through EGFR mislocalization.
• EGFR mislocalization is a key driver of enhanced migration, survival, and altered cell signaling.
• These findings highlight a novel mechanism linking Llgl1 function to EGFR regulation in cancer progression.