Epigenetic Regulation of the PTEN-AKT-RAC1 Axis by G9a Is Critical for Tumor Growth in Alveolar Rhabdomyosarcoma

Area of Science:

• Oncology
• Epigenetics
• Molecular Biology

Background:

• Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer with a poor prognosis.
• Epigenetic modifications, including chromatin changes, play critical roles in cancer development.
• Targeting epigenetic modifiers presents a promising therapeutic strategy for various cancers.

Purpose of the Study:

• To identify chromatin modifiers crucial for ARMS tumor growth.
• To investigate the role of lysine methyltransferase G9a in ARMS.
• To elucidate the downstream mechanisms by which G9a influences ARMS progression.

Main Methods:

• Performed an epigenetic screen to identify key chromatin modifiers.
• Utilized cell viability assays, proliferation, and motility assays in vitro.
• Conducted in vivo tumor growth studies.
• Employed transcriptome and chromatin immunoprecipitation-sequencing (ChIP-seq) analyses.

Main Results:

• Inhibition of G9a significantly impacted ARMS cell viability, proliferation, and motility.
• Targeting G9a reduced tumor growth in vivo.
• G9a directly represses the tumor suppressor PTEN expression in a methyltransferase-dependent manner.
• G9a inhibition leads to decreased AKT and RAC1 activity; RAC1 is a critical downstream effector.

Conclusions:

• G9a inhibition is a viable therapeutic strategy for ARMS.
• G9a regulates ARMS tumor growth through an epigenetic program involving PTEN and RAC1.
• Targeting G9a may offer a novel treatment approach for pediatric alveolar rhabdomyosarcoma.