Cas9 activates the p53 pathway and selects for p53-inactivating mutations

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• CRISPR-Cas9 technology is widely used for genome editing.
• Understanding the unintended consequences of Cas9 expression is crucial.

Purpose of the Study:

• To investigate the genetic and transcriptional effects of Cas9 expression in human cancer cell lines.
• To determine how Cas9 impacts the p53 pathway and DNA repair mechanisms.

Main Methods:

• Gene expression profiling of 165 human cancer cell line pairs and their Cas9-expressing derivatives.
• Messenger RNA and protein level analysis.
• Genetic characterization and competition experiments in isogenic cell lines.

Main Results:

• Cas9 expression upregulated the p53 pathway in wild-type TP53 (TP53-WT) cell lines.
• Elevated DNA repair levels were observed in Cas9-expressing cells.
• Cas9 introduction led to the emergence and expansion of p53-inactivating mutations, with reduced Cas9 activity in TP53-WT cells.

Conclusions:

• Cas9 expression has significant transcriptional and genetic consequences, particularly affecting the p53 pathway.
• The p53 status of cell lines influences Cas9 activity and cellular responses to perturbations.
• Findings have implications for the accurate application of CRISPR-Cas9 genome editing.