Deregulation of DNA damage response pathway by intercellular contact

Area of Science:

• Cell Biology
• Molecular Biology
• Genomics

Background:

• The DNA damage response (DDR) pathway is crucial for maintaining genomic integrity.
• Dysregulation of DDR can affect cancer cell sensitivity to treatments.
• Intercellular contact's role in DDR regulation is not fully understood.

Purpose of the Study:

• To elucidate the mechanism by which intercellular contact regulates the DDR pathway.
• To investigate the role of the cadherin-catenin pathway in DDR protein stabilization.
• To understand the implications for cancer cell apoptosis and DNA damage sensitivity.

Main Methods:

• Western blotting to assess protein levels (H2AX, γH2AX, RNF8).
• Immunoprecipitation and Chromatin Immunoprecipitation (ChIP) assays.
• Analysis of N/E-cadherin, γ-catenin, and LEF-1 interactions and functions.

Main Results:

• Intercellular contact up-regulates N/E-cadherin and γ-catenin, stabilizing histone H2AX and γH2AX.
• γ-catenin and LEF-1 suppress RNF8 ubiquitin ligase, increasing H2AX levels.
• Hyperphosphorylation of DDR proteins occurs with increased H2AX.
• Confluent cells exhibit constitutive apoptosis, independent of further DNA damage, potentially due to impaired p53 activation.

Conclusions:

• The cadherin-catenin pathway provides a novel mechanism for regulating DDR proteins.
• Intercellular contact influences DDR protein levels and function.
• This pathway modulation has implications for cancer biology and therapeutic strategies.