Scientists have confirmed that cancer cells can "remotely disarm" the immune system

U.S. researchers have confirmed that some cancer cells can release a secret weapon to destroy lymph nodes to prevent attacks by the body's immune cells, in order to achieve the effect of "bottom pumping." This explains why most cancers are insensitive to existing immunotherapy, providing ideas for developing new treatments and even cancer vaccines.
cancer cells release small sacs called "exosomes" and play an important role in avoiding immune attacks, researchers at the University of California, San Francisco reported In the Journal of Cells on April 4. The exosome carries the PD-L1 protein that "disarms" the immune cells and arrives in the lymph nodes through the lymphatic system or blood, the base of the immune cells that produce them, destroying immune cell activity at the source.
's recent revolutionary anti-cancer immunotherapy drug, Immune Checkpoint Inhibitors, suppresses PD-L1, the camouflage protein on the surface of cancer cells, and its subject, PD-1, in the body's immune cells, making it impossible for the immune system to recognize and attack cancer cells. But "immune checkpoint inhibitors" are ineffective against many cancers, such as prostate cancer, which has previously been thought to be because they do not produce PD-L1, making immunological drugs "unseeded."
UC San Francisco researchers provided new explanations, finding that cancer cells that are insensitive to "immune checkpoint inhibitors" still produce large amounts of PD-L1 proteins, except that they do not exist on the surface of cancer cells, but are secreted by cancer cells that carry "exosomes" that reach the lymph nodes, and that existing "immune checkpoint inhibitors" do not act on these "exosomes."
in animal experiments, researchers implanted prostate cancer cells from non-reactive "immune checkpoint inhibitors" into healthy mice and found that tumors grew rapidly. But after using CRISPR gene-editing technology to knock out two of the genes responsible for producing "exosomes," although the cancer cells were still able to produce PD-L1 proteins, they were unable to form tumors in mice.
experiment also found that by knocking out the genes responsible for producing "exosomes," these cancer cells can induce the body's immune response, allowing the immune system to re-identify and attack cancer cells, which are expected to be used to develop anti-cancer vaccines in the future. The researchers injected genetically edited "exosome" cancer cells into mice and implanted unregioned cancer cells 90 days later, finding that the latter could not "incognito" the immune system. The researchers believe that after exposure to cancer cells with a lack of "exosomes", the mice's immune system gained a memory of resistance to tumors.Mauro Poggio, a postdoctoral student at the University of California, San Francisco and lead author of the
paper, said there are no cancer drugs clinically that can block the destructive power of the PD-L1 protein "exosome", and understanding its biological mechanisms is the first step in developing new therapies. (Source: Xinhua News Agency Zhou zhou)
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