Cancer cells dodge attack on the way to lymph nodes
Cancer highjacks the immune system
They implanted groups of melanoma cells under the skin of mice and let them form tumors. In some mice, the cancer spread to the lymph nodes, and in other mice, it didn’ t. After several weeks, the researchers injected melanoma cells that don’ t spread to lymph nodes into the veins of the mice and then checked their lungs for cancer.
Melanoma Cells thatt Pass through Lymph More Likely to Spread
Cells thatt take this detour are more resistant to cell death, researchers found.
There were far more tumors in the lungs of mice that had cancer in their lymph nodes than in mice that didn’ t, they found.
So, it appears that spreading to lymph nodes helps cancer metastasize to the lungs, Dr. Engleman said.
Cancer cells dodge attack on the way to lymph nodes
Next, the researchers asked what gives some melanomaa cells the ability to spread to the lymph nodes.
They found thatt cancer cells that had spread to the lymph nodes had higher levels of certain proteins, including PD‐L1 and MHC‐I, than melanoma cells that didn’ t spread. High levels of PD‐L1 and MHC‐I send signals that tell cancer‐fighting immune cells not to attack.
Further studies confirmed that higher levels of PD‐L1 and MHC‐I shielded melanomaa cells from attack by immune cells. More specifically, immune cells called NK cells killed fewer melanoma cells that spread to the lymph nodes than melanoma cells that didn
’ t spread.
“ It’ s quite remarkable what [ cancer cells have
] to dodge on the way to the lymph nodes. There is lots of immune attack,” Dr. Engleman explained.
Cancer highjacks the immune system
The researcherss also explored what happens once cancer gets to the lymph nodes. Similar to what other studies have found, it appears that when cancer cells