Over the course of an animal’s lifespan, cells are continually dividing and, with each cellular division, there is a risk of producing a cancerous mutation. It is expected then that larger animals with long lifespans, like elephants, should be at a higher risk for developing cancer. However, cancer incidence in elephants is extremely low. Why do elephants have this cancer immunity? The answer may lie in the rise of a "zombie gene" during the elephant’s evolutionary history.
In a study published in Cell Reports, scientists investigated the evolutionary record of 53 mammals with varying sizes and lifespans and discovered that elephants, along with close relatives like the manatee, contain a number of duplicate pseudogenes for the transcription factor, leukemia inhibitor factor (LIF) whereas almost all mammals only possess one copy. Although most of these duplicates are nonfunctional, one gene encoding LIF6, has been reanimated over the elephant’s evolutionary history. This "zombie gene" is activated by the tumor suppressor, TP53, in response to low levels of DNA damage and, upon activation, induces cell death. Over time, elephant cells have evolved an enhanced sensitivity to low levels of DNA damage and LIF6 is, in part, responsible for this amplified response. This in turn coincided with the origin of larger bodied mammals, potentially proving advantageous for the evolution of the modern day elephant. Researchers hope by studying the evolution of tumor suppressor genes within animals, like the elephant, will aid in the understanding of cancer resistance and potential lead to identification of a novel target for developing new therapies to fight cancer progression.
New to the GenScript newspage? Feel free to check out our molecular biology services, including our industry-leading gene synthesis service. Or get a Free Quote today
