August 17, 2022

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Why are cancer rates unusually low in elephants?

Why are cancer rates unusually low in elephants?



 

Why are cancer rates unusually low in elephants?


An exciting new study by an international team of scientists has revealed the exact reason for the unusually low incidence of cancer in elephants, one of the largest animals on Earth.

The study found that these mammals carry unique genetic variants that reduce their tumor risk, findings that could help develop new cancer treatments for humans.

 

 

Why are cancer rates unusually low in elephants?

 

 

As an organism ages, its cells continue to replicate, increasing the chance of developing cancerous mutations.

And the bigger the organism, the more cells it has, so the more chance of mutation, and the higher the risk of cancer as you get older.

 

In individual species, this observation is true. From tall humans to large dogs, cancer risk has been found to be positively correlated with body size.

So in theory, large, long-lived animals should experience higher rates of cancer than small, short-lived organisms.

 

But that’s not the case, this dissonance is known as the “Peto’s paradox,” after epidemiologist Richard Peto, who found that the rate of cancer per cell varies between species inconsistent.

In fact, there seems to be little evidence of cancer at all in some of the larger species, such as whales and elephants, who have long lifespans despite their size.

 

While each species is widely believed to have evolved its own unique ability to suppress cancer, elephants have been of particular interest to researchers.

These animals lived a similar lifespan to humans, but despite their size showed few signs of cancer — even at very old age. It is estimated that only 5% of elephants eventually die of cancer, compared to 25% of humans.

 

A landmark study a few years ago identified one of the key ways that these massive mammals may stave off cancer.

Elephants appear to have 20 different copies of a tumor-suppressing gene called p53.

 

This gene encodes a protein also known as p53, which is a key cell protector.

The protein acts a bit like a guard whose job is to stop the cell from dividing when any DNA damage or mutation is detected.

 

When the p53 gene doesn’t work properly, damaged cells multiply and cancerous tissue accumulates.

Dysregulation of this gene is thought to play a role in more than half of all human cancers, but unlike elephants, we only have one copy of the gene.

 

The new study set out to investigate how exactly the various p53 genes in elephants suppress cancer.

 

“This intricate and fascinating study shows that there is much more to elephants than just their impressive size, and we need to not only protect these iconic animals but also study them carefully,” the study reports.

“After all, their genetics and physiology are driven by evolutionary history and today’s ecology, diet and behavior,” explains co-author Fritz Vollarth of Oxford University.

 

The activity of p53 in cells is regulated by another gene called MDM2, which encodes a protein that essentially inactivates the p53 protein.

 

This p53-MDM2 pathway is fundamental to how healthy cells function — p53 steps in to check the health of a cell, and MDM2 stops p53 from triggering cell death by sending a signal that everything is working properly.

New research finds that elephants have an incredibly diverse array of p53 proteins that can increase the way around MDM2 inactivation.

 

In humans, because we only have one copy of the p53 gene, MDM2 doesn’t need much to take over and allow cancer cells to replicate.

But in elephants, the p53 protein has dozens of different molecular shapes, which avoid inactivation of MDM2 and prevent more cancer cells from replicating.

 

“This is an exciting development in our understanding of how p53 helps prevent cancer development,” said Robin Fåhraeus, co-author of the study. “There are several isoforms of p53 in elephants, and their ability to interact with MDM2 different, which provides an exciting new way to reveal the tumor suppressor activity of p53.”

 

The new study provides impressive new insights into the mechanisms by which elephants have evolved to avoid cancer.

In addition to demonstrating how these massive mammals deploy different p53 molecules to suppress the growth of cancer cells, the study also goes some way by confirming that elephants do have more ways to avoid cancer than smaller creatures helps solve Peyto’s paradox.

 

In addition to these academic insights, the new study may also yield clinical results in humans.

By highlighting dozens of new ways in which p53 molecules can be activated, the researchers now propose several new avenues for targeted cancer therapy in humans.

 

 

 

 

 

Why are cancer rates unusually low in elephants?

(source:internet, reference only)


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