NF-κB functions in tumor initiation by suppressing the surveillance of both innate and adaptive immune cells

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Nuclear factor-kappa B (NF-κB) is implicated in tumor development, but its role in early oncogenesis remains unclear.
• The p65 subunit of NF-κB traditionally acts as a tumor suppressor in normal cells by inducing senescence after DNA damage.

Purpose of the Study:

• To investigate the function of NF-κB during the initial stages of tumor formation in a Ras-induced transformation model.
• To elucidate the mechanisms by which NF-κB influences tumor progression and immune evasion.

Main Methods:

• Utilized a mouse model of Ras-induced transformation to study NF-κB activity in preneoplastic cells.
• Analyzed the impact of NF-κB on immune cell interactions, including macrophages and T cells.
• Investigated NF-κB's role in regulating proapoptotic factors and myeloid-derived suppressor cells.

Main Results:

• Following cellular immortalization, the p65 subunit of NF-κB transitions from a tumor suppressor to an oncogene.
• NF-κB protects transformed cells from immune attack by inhibiting macrophage-derived proapoptotic factors (e.g., TNF, nitric oxide).
• NF-κB promotes immune evasion by mitigating T cell cytotoxicity via transforming growth factor beta (TGF-β) and expanding myeloid-derived suppressor cells.

Conclusions:

• NF-κB plays a dual role in cancer, acting as a tumor suppressor early on and an oncogene during later stages.
• NF-κB suppresses both innate and adaptive immune surveillance in the early phases of oncogenesis.
• These findings highlight NF-κB's critical role in immune evasion and suggest its potential as a target for novel immunotherapies.