NONO Protein Regulates the Immune Response in Human Triple-Negative Breast Cancer Cells

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Triple-negative breast cancer (TNBC) presents significant treatment challenges and mortality.
• The role of RNA-binding protein NONO in cancer immune signaling is largely unknown.
• NONO is implicated in tumorigenesis, necessitating investigation into its broader functions.

Purpose of the Study:

• To investigate the role of NONO in regulating immune signaling pathways in TNBC.
• To determine if NONO modulation affects the cGAS/STING pathway and immune response.
• To explore NONO as a potential therapeutic target for enhancing anti-tumor immunity in TNBC.

Main Methods:

• NONO expression was modulated using short hairpin RNA (shRNA) and the chemical inhibitor (R)-SKBG-1 in MDA-MB-231 TNBC cells.
• Assessed cytoplasmic DNA accumulation, micronuclei formation, and activation markers of the cGAS/STING pathway.
• Measured phosphorylation of TBK1, NF-κB nuclear localization, and pro-inflammatory gene transcription (e.g., CCL5).

Main Results:

• NONO depletion induced cytoplasmic DNA accumulation and micronuclei formation.
• Activated the cGAS/STING pathway, evidenced by increased cGAS/STING activation and TBK1 phosphorylation.
• Confirmed NONO's immunosuppressive function, showing enhanced NF-κB activation and pro-inflammatory gene expression upon NONO inhibition.

Conclusions:

• NONO acts as a key immunosuppressive modulator in TNBC.
• Inhibition of NONO enhances anti-tumor immune responses via the cGAS/STING pathway.
• NONO inhibitors may be beneficial in combination therapies, especially for tumors with specific deficiencies or low immune infiltration.