Cholangiocyte ciliary defects induce sustained epidermal growth factor receptor signaling

Area of Science:

• Cell Biology
• Molecular Signaling
• Hepatology

Background:

• Primary cilia are crucial for sensing extracellular signals and their dysfunction is linked to liver diseases.
• Aberrant epidermal growth factor receptor (EGFR) signaling is implicated in cholangiocarcinoma and polycystic liver disease.

Purpose of the Study:

• To investigate the relationship between primary cilia and the EGFR signaling pathway.
• To understand how primary cilia regulate EGFR signaling in liver cells.

Main Methods:

• Utilized liver-specific intraflagellar transport 88 knockout mice, Pkhd1 mutant rats, and human cell lines.
• Employed histone deacetylase 6 (HDAC6) inhibitors to restore primary cilia function.
• Assessed EGFR degradation, localization, and downstream signaling (ERK phosphorylation).

Main Results:

• Cilia-deficient cholangiocytes exhibited persistent EGFR activation due to impaired degradation.
• Restoring primary cilia with HDAC6 inhibitors accelerated EGFR degradation and reduced aberrant signaling.
• Combined EGFR and HDAC6 inhibition showed synergistic antiproliferative effects in disease models.

Conclusions:

• Primary cilia dysfunction leads to impaired EGFR turnover and promotes liver disease progression.
• Therapies targeting primary cilia restoration offer a potential treatment strategy for EGFR-driven liver diseases.
• Restoring ciliary function is a promising approach for polycystic liver disease and cholangiocarcinoma.