Acetylation of the cell-fate factor dachshund determines p53 binding and signaling modules in breast cancer

Area of Science:

• Molecular Biology
• Oncology
• Genetics

Background:

• Breast cancer is a significant global health concern.
• The Drosophila Dac gene, a homolog of DACH1, is known to inhibit epidermal growth factor receptor (EGFR).

Purpose of the Study:

• To investigate the role of endogenous DACH1 in human breast cancer.
• To elucidate the interaction between DACH1 and p53 in breast cancer cells.
• To understand the regulatory mechanisms of DACH1-p53 interaction and its impact on breast cancer growth.

Main Methods:

• Co-localization studies of DACH1 and p53.
• Co-immunoprecipitation to assess protein-protein binding.
• Chromatin immunoprecipitation sequencing (ChIP-Seq) to identify common target genes.
• Analysis of DACH1 phosphorylation and p53 mutations in breast cancer cell lines.
• Investigation of NAD-dependent deacetylation effects on DACH1-p53 binding.
• Gene expression analysis of p21CIP1 and RAD51.

Main Results:

• Endogenous DACH1 co-localizes with p53 in a nuclear, extranucleolar compartment and binds to p53 in human breast cancer cells.
• DACH1 and p53 bind to common genes, as shown by ChIP-Seq.
• DACH1-mediated inhibition of breast cancer cell growth is dependent on functional p53.
• Specific p53 mutations (R248Q, R273H) evade DACH1 binding.
• DACH1 phosphorylation at S439 inhibits p53 binding, while p53 phosphorylation at S15/S20 enhances it.
• NAD-dependent deacetylation of DACH1 at K628 inhibits p53 binding.
• DACH1 represses p21CIP1 and induces RAD51, a pattern observed in basal breast cancer.

Conclusions:

• DACH1 inhibits breast cancer cellular growth through a mechanism dependent on NAD and p53.
• Direct protein-protein association between DACH1 and p53 is crucial for this inhibition.
• The interaction is modulated by phosphorylation and deacetylation, offering potential therapeutic targets.