Sirtuin 2 mutations in human cancers impair its function in genome maintenance

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• Sirtuin 2 (SIRT2) is a deacetylase crucial for maintaining genome integrity and preventing cancer.
• While Sirt2 deficiency in mice causes tumors, the role of somatic SIRT2 mutations in human cancers remains unclear.

Purpose of the Study:

• To investigate the functional impact of naturally occurring, cancer-associated SIRT2 mutations on its deacetylase activity and tumor-suppressive functions.
• To elucidate the mechanistic basis by which SIRT2 mutations contribute to genomic instability in human tumors.

Main Methods:

• Structural analysis, bioinformatics, and functional assays were employed to study SIRT2 mutations.
• Assessed the impact of mutations on SIRT2's catalytic activity, protein levels, localization, and substrate binding.
• Evaluated the ability of mutant SIRT2 proteins to rescue phenotypes associated with SIRT2 deficiency, including replication stress sensitivity and DNA damage response.

Main Results:

• Cancer-associated SIRT2 mutations at conserved sites impair its ability to deacetylate DNA-damage response proteins.
• Mutations disrupt SIRT2's catalytic activity or protein levels, but not its localization or substrate binding.
• SIRT2 mutant proteins failed to restore normal replication stress response, ATR-interacting protein (ATRIP) focus formation, and prevent spontaneous DNA damage and micronuclei formation in cancer cells.

Conclusions:

• Somatic SIRT2 mutations contribute to genomic instability by impairing its deacetylase activity or reducing its protein levels.
• These findings provide a mechanistic understanding of how SIRT2 mutations drive tumor suppression and genome maintenance.
• The study highlights the biological and clinical significance of SIRT2 mutations in cancer development.