Topic: Biology
Scientists at Nagoya University in Japan discovered that a protein called complement C3 can help the immune system fight cancer. They found that when C3 is produced locally within a tumor, it prevents immune-suppressing cells from entering the tumor and helps the immune system attack cancer cells.
Cancer tumors are surrounded by normal cells called fibroblasts. These fibroblasts produce a protein called complement C3, which was previously thought to only be made in the liver and released into the bloodstream. But scientists at Nagoya University discovered that C3 produced locally within the tumor is actually very important for fighting cancer.
The researchers found that when C3 is produced locally, it prevents immune-suppressing cells called myeloid cells from entering the tumor. These cells can weaken the body's ability to attack cancer. By keeping them out, locally produced C3 gives the immune system a better opportunity to recognize and fight tumor cells.
The team conducted experiments in mice that allowed them to distinguish between C3 from different sources. They found that when the amount of liver-produced C3 was reduced by 90%, an immunotherapy drug (anti-PD-1 antibody) remained just as effective as it was in mice with normal C3 levels. But when they stopped fibroblasts inside the tumor from producing C3, the same treatment became less effective.
The researchers also tested a drug designed to imitate the way C3 blocks myeloid cells from entering tumors. This approach allowed immunotherapy to work against tumors that had previously resisted treatment and significantly extended survival in mice.
Why It Matters
This discovery could lead to new ways of fighting cancer, especially for patients whose tumors do not produce enough C3 naturally. It may also help doctors identify which patients are most likely to benefit from immunotherapy and develop new treatment options for cancers that don't respond well to current treatments.
Key Facts
- Scientists at Nagoya University in Japan discovered a protein called complement C3 that helps the immune system fight cancer.
- C3 produced locally within a tumor prevents immune-suppressing cells from entering the tumor and helps the immune system attack cancer cells.
- The researchers found that reducing liver-produced C3 by 90% did not affect the effectiveness of immunotherapy in mice.
- A drug designed to imitate the way C3 blocks myeloid cells from entering tumors allowed immunotherapy to work against resistant tumors and extended survival in mice.
- Researchers also tested this discovery on human lung cancer samples, which showed that patients with higher levels of C3 in the tissue surrounding cancer cells experienced better treatment results.
Key Terms
- Complement C3
- A protein produced by the liver and other tissues to help the immune system fight infections.
Implications
This discovery could lead to new ways of fighting cancer, especially for patients whose tumors do not produce enough C3 naturally. It may also help doctors identify which patients are most likely to benefit from immunotherapy and develop new treatment options for cancers that don't respond well to current treatments.
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