The U1 spliceosomal RNA is recurrently mutated in multiple cancers

Area of Science:

• Oncology
• Genomics
• Molecular Biology

Background:

• Cancer arises from genomic alterations, with known drivers primarily in coding genes.
• Noncoding drivers and alterations in spliceosomal RNAs are understudied cancer mechanisms.
• Aberrant RNA splicing is implicated in cancer, but mutations are mainly found in protein-coding factors.

Purpose of the Study:

• To investigate noncoding alterations in spliceosomal RNAs as potential cancer drivers.
• To characterize a specific recurrent mutation in U1 small nuclear RNA (snRNA).
• To elucidate the functional and clinical implications of U1 snRNA mutations in cancer.

Main Methods:

• Somatic mutation analysis of U1 snRNA across various tumor types.
• Functional studies to assess the impact of U1 snRNA mutations on RNA splicing.
• Clinical data analysis correlating U1 snRNA mutations with patient outcomes and risk factors.

Main Results:

• A recurrent A>C somatic mutation was identified in U1 snRNA in multiple tumor types.
• This mutation alters U1 snRNA's base-pairing at the 5' splice site, leading to aberrant splicing.
• The mutation is associated with heavy alcohol use in hepatocellular carcinoma and an aggressive subtype of chronic lymphocytic leukemia, and confers an adverse prognosis.

Conclusions:

• U1 snRNA harbors a noncoding driver mutation contributing to cancer development.
• This discovery reveals a novel mechanism of aberrant splicing in cancer.
• The U1 snRNA mutation represents a potential new therapeutic target and highlights the need for broader driver discovery in noncoding regions.