Cholangiocytes' Primary Cilia Regulate DNA Damage Response and Repair

Area of Science:

• Cell Biology
• Cancer Research
• Genetics

Background:

• Primary cilia are implicated as tumor suppressors in cholangiocarcinoma (CCA), but their role in DNA damage response (DDR) is unclear.
• Understanding cilia's function in DNA repair is essential for developing novel CCA therapies.

Purpose of the Study:

• To investigate the role of primary cilia in DNA damage response and repair in cholangiocarcinoma.
• To determine how the loss of primary cilia affects DNA repair protein localization and function in CCA cells.

Main Methods:

• Utilized human cholangiocyte cell lines with induced deciliation (shRNA/CRISPR targeting IFT20, IFT88, KIF3A) and genotoxic stress (cisplatin, MMS, irradiation).
• Assessed DNA repair protein colocalization at cilia, cell survival, cell cycle, apoptosis, DNA damage (comet assay, γH2AX), and DDR protein expression.
• Generated an in vivo liver-specific IFT88 knockout mouse model.

Main Results:

• DNA repair proteins (RAD51, ATR, PARP1, CHK1/2) localized to cilia; deciliated cells showed impaired DNA repair and reduced survival under genotoxic stress.
• Deciliation led to increased DNA damage (γH2AX, comet assays) and S-phase arrest, with elevated γH2AX observed in vivo.
• Key DDR regulators (ATM, p53, p21) were downregulated in deciliated cells post-irradiation.

Conclusions:

• Primary cilia play a critical role in regulating DNA repair pathways and maintaining genome stability in cholangiocytes.
• Loss of primary cilia compromises DNA damage response, leading to increased genomic instability and reduced cell survival in CCA.
• Targeting cilia-associated mechanisms represents a potential novel therapeutic strategy for cholangiocarcinoma.