Elevated DDX21 regulates c-Jun activity and rRNA processing in human breast cancers.

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• DDX21 (RNA helicase) is implicated in RNA processing and transcription.
• High DDX21 expression is observed in various cancers, including breast cancer.
• Its role in breast tumorigenesis remains largely unknown.

Purpose of the Study:

• Investigate the role of DDX21 in breast cancer development.
• Determine the mechanisms by which DDX21 promotes tumorigenesis.
• Evaluate DDX21 as a potential therapeutic target.

Main Methods:

• Immunohistochemistry on 187 breast cancer tissues.
• Indirect immunofluorescence for subcellular localization.
• DDX21 knockdown assays (apoptosis, rRNA processing, soft agar, xenografts).
• AP-1 transcriptional activity analysis (luciferase reporter, qRT-PCR).

Main Results:

• DDX21 is highly expressed in breast cancer tissues and cell lines, primarily in the nucleus.
• DDX21 expression correlates with proliferation and is induced by EGF signaling.
• DDX21 is essential for c-Jun phosphorylation and AP-1 activity, and promotes rRNA processing.
• DDX21 knockdown reduces breast cancer cell proliferation, tumorigenicity in vitro and in vivo, and induces apoptosis.

Conclusions:

• DDX21 promotes breast tumorigenesis via AP-1 activation and rRNA processing.
• DDX21 expression may indicate higher proliferation potential in breast cancer.
• DDX21 represents a potential therapeutic target for a subset of breast cancer patients.