What mechanism did the authors propose for Fusobacterium promoting tumor growth in the GI tract?

• A. Suppression of inflammatory signaling
• B. Promoting NF-κB signaling via TLR4/MYD88
• C. Inhibiting cell proliferation
• D. Blocking immune cell recruitment

Answer: (B)

The mechanism being tested is that Fusobacterium promotes tumor growth by activating inflammatory signaling through the TLR4/MyD88 pathway, leading to NF-κB activation in intestinal tissues. When Fusobacterium nucleatum interacts with epithelial or immune cells, TLR4 recognizes bacterial components and signals via the MyD88 adaptor, triggering NF-κB to enter the nucleus and drive transcription of pro-inflammatory and pro-survival genes. This results in a cascade of cytokines and mediators such as IL-6, IL-8, TNF-α, and others that create a pro-tumor microenvironment, promoting cell proliferation, resistance to apoptosis, angiogenesis, and immune cell recruitment that supports tumor growth. Evidence from studies shows that activating this pathway correlates with higher NF-κB activity in tumors associated with Fusobacterium, and disrupting TLR4/MyD88 signaling can mitigate these pro-tumor effects. The other options describe mechanisms that would dampen inflammation or directly inhibit growth or immune recruitment, which would not explain how Fusobacterium promotes tumor development in the GI tract.