Several forms of anticancer therapy rely on what is known as immunotherapeutic anticancer strategies; therapies that encourage the body’s natural defenses, such as cytotoxic T lymphocytes, to aid in destroying tumors.
These immunotherapeutic methods are often not effective at removing established tumors for a number of reasons including a loss of the ability of the cytotoxic T lymphocytes to recognize the tumor and a physical barrier separating the lymphocytes and the tumor. Following this research it would also appear that tumors secrete fatty acids which further inhibit the cytotoxic T lymphocytes’ ability to kill tumor cells.
Dr Alan Kleinfeld of the Torrey Pines Institute for Molecular Studies in San Diego said: “Human breast cancer cells, but not normal tissue from the same breast, produce very large amounts of the type of free fatty acids that block the cytotoxic T lymphocytes. Thus the cancer may have a way of defending itself against attack by the immune system, thereby reducing the potential efficacy of novel anti cancer therapies that rely on a functioning immune system.”
The free fatty acids act against cytotoxic T lymphocytes by blocking a number of the lymphocytes’ signaling events. For example, they keep certain proteins from being phosphorylated and they also prevent an increase in intracellular calcium that is essential for the cytotoxic T lymphocytes to kill the tumor cells. Dr Kleinfeld suspects that these signaling events are being blocked at the cells’ membranes.
These results raise possibilities of new therapeutic targets for cancer, such as those that may transport free fatty acids out of the tumor. Alternatively, free fatty acid levels in the blood could be used to help gauge the aggressive potential of a tumor.