Cancer cells always seem to be one step ahead of medical researchers. Tumours grow and spread by piggy-backing on the molecular systems in our body that evolved to keep us healthy. This is part of why cancers are so difficult to treat – because drugs often hurt healthy cells as well as the cancerous ones.
Recent research shows that cancer cells are using the same genes that first evolved to allow pregnancy in animals. For example, embryos and cancer cells both use the same genetic systems to avoid immune rejection.
During pregnancy, the embryo must come into contact with its mother’s uterus. Since the embryo is genetically different from its mother, this situation is not unlike what happens during organ transplants, where the patient needs to take immunosuppressant drugs to prevent their body rejecting the donated organ. The mother’s immune system should identify the embryo as foreign and attack it, but this obviously doesn’t happen too often because healthy babies are born all the time.
So how do embryos avoid immunological rejection? In part, this process involves “switching off” some of the immune genes on the surface of the embryo’s cells that identify it as foreign, effectively allowing the embryo to hide from the maternal immune system and avoid rejection.
Cancer cells are the body’s own cells, but they have undergone mutations that make...
