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Zombie Genes

When we were nominated for the Sunshine Blogger Award earlier this month (read this post here), one of the questions The Catalyst in Me asked us “If you could be an animal which one would you be and why?”. And we answered: “An elephant - mainly because they are a keystone species.” and we thought it right to explain a bit more about the elephant as we didn’t really do it justice. Also, World Elephant Day was on the 12th August this year - so it only seems right.

World Elephant Day was started six years ago by Patricia Sims and the Elephant Reintroduction Foundation of Thailand with the aim to voice the issues threatening elephants. Elephant populations have decreased significantly by a whopping 62% and have been classed as an endangered species since 1989. Poachers who hunt elephants for their meat, body parts and tusks are largely responsible for this troubling decrease in the number of wild elephants.

As a keystone species , elephants are very important animals of Africa and Asia. Elephants are a phenomenal animal and a central tourist attraction. Additionally, in dry seasons, elephants are able to use their tusks to dig into the ground to get water, aiding their survival and other animals in these drier climates. Also, elephants play a huge role in seed dispersal maintaining the biodiversity of their ecosystems.

One of the most recent and most fascinating discoveries are about elephants is the recent finding of ‘zombie genes’ which contribute to the fact that elephants rarely get cancer (less than 5% of elephants get cancer compared to an estimated 40% of humans). Cancer is a class of diseases characterised by increased cell growth leading to tumours (lumps of tissue) or in the cases of leukemia, abnormal cell division in the bloodstream. No matter the type, cancer is a devastating disease.

Photo: Elephant family at sunset, Jaroslaw Grudzinski

The risk of certain hereditary cancers has been discovered by scientists to be linked to specific genetic mutations in tumour suppressor genes (i.e. BRCA1, p53 OR TP53). The University of Chicago recently released a paper that found that most mammalian genomes encode for a single LIF (leukemia inhibitory factor) gene, however the manatee, rock hyrax and African elephant have 7-11 additional copies of the LIF gene. LIF6 (the zombie gene) in unique to elephants and is a “reanimated pseudogene that kills cells when expressed”. Elephant LIF6 is upregulated in response to TP53 in response to DNA damage and therefore contributes to cancer resistance (Vazquez et al., 2018).

It can be speculated that the biggest animals should have the highest risk of developing tumours than smaller animals - this is true within species. But differences in susceptibility amongst species differs: for instance, elephants (and naked mole rats) have the lowest known cancer rates (despite being the largest land animals). The observed difference in LIF gene expression in the elephant is likely to have been a preventative evolutionary modification against such predisposition to tumour growth. Elephant physiology has mastered this and is protecting elephants from the likelihood of tumour growth.

By understanding how these genes reduce uncontrolled cell division and ultimately the incidence of cancer is a step forward to the ultimate goal to transfer these cells into humans and work towards lowering the incidence of cancer.

More on elephants:

Cancer Facts and Figures 2018, American Cancer Society

By Tomi Akingbade, Founder

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