Elephants are the biggest land animal at this time, much bigger than human. While human body is made of more than 30 trillion cells, then elephant’s body is definitely made of much more cells to keep the animal’s body work.
The thing is, every single cell in our body, and elephant’s body too, will die and regenerate new ones from time to time. However, the new cells are not always perfect, caused by genetic errors and may turn into what so called cancer.
We know that cancer is our biggest enemy in this era. Simply it is friend of no one. Having more than 30 trillion cells means bigger risk for human to develop the ‘mistake’, even one mishap can lead to the terror.
So, can we say that elephants are in bigger threat of cancer compared to human? The fact is, no. New study found that elephants have smaller risk to develop cancer compared to human. So, how can this possible?
There is no simple answer to the questions above, even researchers said that this is a kind of paradox. In some way, elephants, whose body consist of tens times more amount of cells, having less chance to develop cancer compared to human. Researchers call it as Peto’s Paradox.
“If every cell has some chance of becoming cancerous, large, long-lived organisms should have an increased risk of developing cancer compared to small, short-lived organisms. The lack of correlation between body size and cancer risk is known as Peto’s Paradox,” as stated in a study.
In human body, we have a kind of ‘soldier’ gene called P53. “P53 can recognize DNA damage and then go, ‘OK what are our options?” said biologist Amy Boddy. To avoid further development into cancer cells, P53 are repairing the damages. However, when the damage is irreparable, P53 are the ones taking the order to kill those damaged cells.
This gene can also be found in elephant’s body. Logically, with larger field of task, the gene should find it more difficult to track down and inspect every single cell in elephant’s body. However, the gene in elephant’s body can do the job very well.
There are two reasons why the gene works very well in elephant’s body, as stated by researchers in the newest study. First is there are more copies of them in the animal’s body, and second is because the gene in elephant’s body are more ruthless. Well, if it is a gene, should it work the same in every single living thing?
The Zombie Gene
Researchers are not satisfied with mere assumption, thus they conducted a research to find out the answer. “We were curious if elephants had more copies of genes that have tumor suppressor functions, including LIF which is a known tumor suppressor gene,” said Vincent Lynch, evolutionary biologist at the University of Chicago who contributed to the study.
From that study, they found out an interesting fact about elephant’s body. A kind of gene called LIF6 which is currently extinct in any other mammals was found in the body of elephants. This gene works together with P53 to give the more ‘ruthless’ result to fight cancer.
“When it gets turned on by damaged DNA, it kills that cell, quickly. This is beneficial, because it acts in response to genetic mistakes, errors made when the DNA is being repaired. Getting rid of that cell can prevent a subsequent cancer,” he stated.
This gene is called a zombie gene, since it was thought to be extinct in any animal. However, a small evolution in modern elephant called up for this gene and woke it up again in the giant animal’s body.
“Hence, zombie. This dead gene came back to life,” said Lynch. Researchers were surprised to find the existence of this gene in modern elephant body. Even they ruled out the possibility at the beginning of the study, yet after meeting a dead end they brought up the possibility again.
P53 and LIF6 are the genes that actually can be found in every single mammal. Yes, we also have the P53 gene and LIF6 too. Human have one copy of the ‘soldier’ gene to protect us from cancer development.
We also have the LIF6 gene too, however this gene is dormant in our body. It means that the gene doesn’t actually do anything and just exists. In this condition, our LIF6 gene belongs to the category of pseudogenes.
But the condition is different with elephants. As said before that we have one copy of P53 gene, but elephants have many more copies of it. In fact, elephants have about 10 to 20 copies of this gene. It makes the ‘scanning’ work easier.
While for the execution, the LIF6 gene in an elephant’s body is active, hence called a zombie. Thus, while in our body we can only depend on the one copy of P53 gene to avoid cancer, in elephant’s body the 20 copies of P53 are aided by the working LIF6 gene.
This is the shocking reason behind their cancer-free life. But if you wish we had active LIF6 gene, you are wrong. The gene is dormant or some reason,which is because of its destructive nature. LIF6 gene is very strict in its work, and a simple mistake can destroy anything.
“It’s like having a trap in your genome. If they accidentally get reactivated, they’ll cause cells to [self-destruct], and unless there’s a good reason for that, you don’t want your cells to randomly die,” said Lynch.
In Elephant’s body, the gene’s power is actually suppressed, meaning that even in killing cancer the gene doesn’t work alone. Researchers found out that when they removed the gene, elephant cells were less sensitive to damaged DNA, but it was just slightly less.
“It makes sense for elephants to have multiple mechanisms of cancer resistance since they’re large and so long-lived,” said Lisa Abegglen, the researcher who helped to show that elephants have more than a copy of P53.
The next step after this discovery is how to find a way it can benefit human. “Maybe we can find ways of developing drugs that mimic the behaviors of the elephant’s LIF6 or of getting cancerous cells to turn on their existing zombie copies of the LIF gene,” said Lynch.