PHF6 cooperates with SWI/SNF complexes to facilitate transcriptional progression

Area of Science:

• Molecular Biology
• Cancer Genomics
• Chromatin Biology

Background:

• SWI/SNF (BAF) chromatin remodeling complexes are frequently mutated in cancer.
• Mutations in SWI/SNF subunits, like SMARCB1, drive tumorigenesis.
• The PHF6 gene is also implicated in the neurodevelopmental disorder Coffin-Siris syndrome.

Purpose of the Study:

• To investigate the functional consequences of SWI/SNF mutations in cancer.
• To identify genetic dependencies in SMARCB1-mutant cancers.
• To elucidate the mechanistic link between SWI/SNF and PHF6.

Main Methods:

• Genome-scale CRISPR-Cas9 screening in 896 cell lines.
• Contribution of ten SMARCB1-mutant rhabdoid tumor cell lines.
• In vivo studies and co-localization assays.

Main Results:

• PHF6 was identified as essential for the survival of rhabdoid tumors.
• This PHF6 dependency was confirmed in other SMARCB1-deficient cancers in vivo.
• PHF6 localizes with SWI/SNF at promoters and is crucial for maintaining active chromatin.

Conclusions:

• Loss of SMARCB1 leads to disrupted SWI/SNF complex stability and function.
• PHF6 is critical for maintaining active chromatin and cell survival in SMARCB1-mutant cancers.
• This work establishes a mechanistic link between SWI/SNF and PHF6 mutations in Coffin-Siris syndrome and cancer.