p53-intact cancers escape tumor suppression through loss of long noncoding RNA Dino

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Long noncoding RNAs (lncRNAs) are increasingly implicated in cancer, but their direct functional links to genetic alterations remain unclear.
• The DINO/CDKN1A locus is associated with cancer, yet the specific role of the lncRNA DINO in tumorigenesis is not well understood.

Purpose of the Study:

• To investigate the function of the lncRNA DINO in tumor suppression.
• To determine the mechanism by which DINO affects cancer development and its relationship with p53 signaling and p21.

Main Methods:

• Utilized genetically defined mouse models to study the in vivo function of Dino.
• Analyzed DNA methylation patterns in human cancers to identify alterations affecting the DINO/CDKN1A locus.
• Investigated the impact of DINO silencing on p53 signaling and apoptosis.

Main Results:

• DINO suppresses tumor formation independently of the p21 protein.
• Loss of Dino alleles leads to impaired p53 signaling and apoptosis, causing a haplo-insufficient tumor suppressor phenotype.
• Recurrent hypermethylation of a specific region in the DINO/CDKN1A locus silences DINO in human cancers, while sparing CDKN1A.
• DINO silencing impairs the p53 signaling pathway in trans and is mutually exclusive with TP53 alterations.

Conclusions:

• DINO is a critical lncRNA tumor suppressor that functions independently of p21.
• Hypermethylation-induced silencing of DINO is a recurrent mechanism in human cancers, contributing to the evasion of p53-dependent tumor suppression.
• DINO and TP53 form a tumor suppressor module frequently disrupted in cancer.