Tumor suppressor PNRC1 blocks rRNA maturation by recruiting the decapping complex to the nucleolus

Area of Science:

• Genomics
• Molecular Biology
• Cancer Research

Background:

• Focal deletions are common in cancer genomes, but identifying the specific tumor-suppressor genes involved is challenging.
• Understanding these genes is crucial for developing targeted cancer therapies.

Purpose of the Study:

• To computationally identify tumor-suppressor genes within frequently deleted regions of the cancer genome.
• To elucidate the function of the identified gene PNRC1 in cancer suppression.

Main Methods:

• Utilized non-negative matrix factorization (NMF) on The Cancer Genome Atlas (TCGA) dataset to identify a metagene signature.
• Investigated the interaction of PNRC1 with cytoplasmic decapping machinery and its nucleolar translocation.
• Assessed the impact of PNRC1 on ribosomal RNA maturation and oncogene-driven proliferation.

Main Results:

• Identified a metagene signature characterized by hemizygous deletions, reduced expression, and nucleolar function, including the gene PNRC1.
• PNRC1 interacts with and translocates the DCP1α/DCP2 decapping complex to the nucleolus.
• This translocation reduces 5'-capped U3 and U8 snoRNAs, impairs rRNA maturation, and suppresses oncogene-induced proliferation (RAS, MYC).

Conclusions:

• PNRC1 acts as a tumor suppressor by relocating cytoplasmic decapping machinery to the nucleolus.
• This mechanism tightly regulates ribosomal RNA maturation, thereby inhibiting cancer cell proliferation.
• Uncovered a novel tumor suppression pathway involving nucleolar regulation of rRNA processing.