Tumors must evade the immune system to grow and spread, causing cancer. One of the ways tumor cells hide is by displaying proteins that tell immune cells that all is well. New cancer treatments, called checkpoint blockade therapies, work by telling T cells to ignore those protein markers and attack the cells. But this therapy doesn't always work.
"There are tumors that do not respond to these therapies, indicating that they must have additional mechanisms to inhibit the immune response," says Virginia Shapiro, Ph.D., co-leader of the Mayo Clinic Cancer Center Immunology Program. In a paper, published in Cancer Immunology Research, Dr. Shapiro and her team demonstrate one of those mechanisms. In tumors that overexpress the enzyme, ST8Sia6, a function of macrophages, is altered to inhibit immune response.
"In some cancers overexpression of ST8Sia6 in tumors correlates with poor outcome," says Dr. Shapiro. "In the paper, we provide the first evidence as to why ST8Sia6 expression on tumors may enhance tumor growth by inhibiting the immune response."
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