A p21-ZEB1 complex inhibits epithelial-mesenchymal transition through the microRNA 183-96-182 cluster

Area of Science:

• Molecular Biology
• Cancer Research
• Epigenetics

Background:

• The tumor suppressor p21 is a cell cycle inhibitor and transcription corepressor.
• MicroRNAs (miRNAs) play critical roles in gene regulation and cellular processes.
• The epithelial-mesenchymal transition (EMT) is a key process in development and cancer metastasis.

Purpose of the Study:

• To identify microRNAs regulated by p21.
• To investigate the role of p21-regulated miRNAs in EMT.
• To elucidate the molecular mechanisms underlying p21's regulation of miRNA clusters and EMT.

Main Methods:

• Small RNA sequencing to identify p21-regulated miRNAs.
• Analysis of miRNA expression in p21(+/+) and p21(-/-) cells.
• EMT induction models, genome-wide target identification, and molecular assays (e.g., reporter assays, ChIP) to study regulatory mechanisms.

Main Results:

• Loss of p21 downregulated miR-200b-200a-429, miR-200c-141, and miR-183-96-182 clusters.
• p21 deficiency induced EMT, cell migration, and invasion, which were reversed by miRNA reintroduction.
• p21 directly interacts with ZEB1 at the miR-183-96-182 promoter, inhibiting ZEB1-mediated repression.

Conclusions:

• p21 loss promotes EMT through downregulation of specific miRNA clusters.
• The miR-183-96-182 cluster, regulated by p21 and targeting EMT-promoting factors like ZEB1, plays a critical role in suppressing EMT.
• A reciprocal feedback loop exists where p21 inhibits ZEB1-mediated repression of the miR-183-96-182 cluster, highlighting a novel regulatory mechanism in EMT.