A new study has highlighted the significant role of the protein BRD4 in helping triple-negative breast cancer evade the body’s immune system. Research using mouse models showed that BRD4 increases the production of GM-CSF, a molecule that leads to the activation of certain immune cells called macrophages. These macrophages then display higher levels of PD-L1, a protein that allows cancer cells to hide from the immune response. This process makes it difficult for treatments that target the immune system to be effective.
Scientists found that BRD4 directly binds to specific regions of DNA that control GM-CSF production. It also changes these DNA regions by increasing certain chemical marks, which boosts GM-CSF production further. BRD4 supports this process by raising the levels of pyruvate and lactate, chemicals important for these DNA modifications. When BRD4 is blocked, tumor growth slows and the activity of macrophages drops. However, adding GM-CSF can rescue these effects, confirming the link between BRD4, GM-CSF, and immune cell function.
Researchers tested two inhibitors, JQ1 and MS402, which target BRD4. When these inhibitors were used together with antibodies against GM-CSF, tumor growth decreased even more. This combination therapy also changed the environment around the tumor, making it easier for the immune system to attack the cancer.
The findings reveal a new mechanism behind how triple-negative breast cancer avoids immune responses. By interfering with BRD4 and GM-CSF, scientists believe it may be possible to improve treatment for this aggressive form of breast cancer.
Experts suggest that future therapies could combine drugs that block BRD4 with treatments targeting GM-CSF. This new approach could help overcome resistance to current immune treatments and offer hope to patients with triple-negative breast cancer.
